THE STUDY ON INTRODUCTION OF RENEWABLE ENERGIES IN RURAL AREAS IN MYANMAR FINAL REPORT. Volume 4 Main Report Manuals for Sustainable Small Hydros

Transcription

1 THE STUDY ON INTRODUCTION OF RENEWABLE ENERGIES IN RURAL AREAS IN MYANMAR FINAL REPORT Main Report Manuals for Sustainable Small Hydros Part 4-1 Part 4-2 Part 4-3 Part 4-4 O&M Manual-Small Hydros Design Manual-Small Hydros Design Manual-Village Hydros Institutional and Financial Aspects

2 THE STUDY ON INTRODUCTION OF RENEWABLE ENERGIES IN RURAL AREAS IN MYANMAR Final Report Manuals for Sustainable small Hydros Part 4-3 Design Manual Village Hydros 1. Introduction Power Sources for Village Schemes Village Schemes with Village Hydro Supports to Village Schemes Procedure for Village Scheme Implementation Investigation and Planning Estimate of Electrification Demand and Required Power Required Head and Discharge for Village Hydro Investigation of Hydropower Potential Basic Design of Civil Structures Layout of Waterway System Basic Dimensions of Waterway System Intake Power Canal Headtank Penstock Powerhouse Tailrace Design of Hydro-mechanical and Electrical Equipment Planning of Turbine, Generator, Transformer, and Distribution Lines Turbines Turbine Manufacturing for Village Hydro Generators Power Transmission Mechanism Transmission Lines Step-up Transformer...68 i

3 LIST OF TABLES Table 1 Basic Assumptions on Consumers and Unit Power Demand... 7 Table 2 Power Demand by Village Size... 8 Table 3 Required Generator Capacity by Village Size... 9 Table 4 Required Discharge by Available Head Table 5 Sample Calculation of Required Generator Capacity and Discharge Table 6 Sample Calculation of Waterway Dimensions Table 7 Basic Dimensions of Waterway System Table 8 Basic Dimensions of Crossflow-type Runner for Village Hydro Table 9 Nos. of Blade and Pitch Table 10 Runner Diameter and Blade Thickness Table 11 Application of Crossflow-type Turbine Table 12 Dimension Table of Pillow Block Type Bearing Table 13 Oil Seal Dimensions Table 14 Types of Generator Table 15 Conductor Size and Transmission Distance Table 16 ACSR Conductor Size and Max. Distance for Single Phase Transmission at 400 V and 230 V Table 17 ACSR Wire Size and Max. Distance for Single Phase Transmission at 600 V and 230 V Table 18 ACSR Wire Size and Max. Distance for Three Phase Transmission at 600 V and 230 V LIST OF FIGURES Figure 1 Three Power Sources of Village Schemes... 1 Figure 2 Home and Community Hall Lighting with Solar/Wind-Energized Batteries... 2 Figure 3 Framework for Preliminary Selection of Form of Renewable Energy by Location. 2 Figure 4 Typical Village Scheme... 3 Figure 5 Village Scheme with Power Station at Distant Location... 3 Figure 6 Supporters of Village Schemes... 4 Figure 7 Procedure for Village Scheme Implementation... 5 ii

4 Figure 8 Seasonal Changes of River Flow and Power Discharge Figure 9 Discharge Measurement by Float Figure 10 H-Q Curve Figure 11 Leveling with Water Hose Figure 12 Application Range of Turbine Type for Village Hydro Figure 13 Vertical shaft Propellar Turbine Figure 14 Package-type Micro Turbine Generator Figure 15 Pico Hydro Figure 16 Flow in Crossflow Turbine Figure 17 Outer Appearance of Runner Structure Figure 18 Dimensions of Runner Blade Figure 19 Casing Dimension of Clossflow-type Turbine Figure 20 Casing Dimension of Overshot Banki Turbine Figure 21 Casing Dimension of Undershot Banki Turbine Figure 22 Nozzle Dimension of Banki Turbine Figure 23 Application of Overshot Crossflow Turbine to Drop-Structures Figure 24 Example of Application of Undershot Crossflow to Canal Figure 25 Structure of Ground Packing Figure 26 Types of Oil Seal Figure 27 Alternating Current of Three-phase and Single Phase Figure 28 Principle and characteristics of AC generator Figure 29 Compound Winding Single Phase Generator Figure 30 Load Characteristics of Compound Winding Single Phase Generator Figure 31 Condenser Excitation Figure 32 Example of No-load Voltage and Current Figure 33 Revolution Speed and Residual Voltage Figure 34 Pulley Ratio by V-belt Figure 35 Voltage Drop of Transmission Lines Figure 36 V Wire Connection Figure 37 V Connection for 400/230 V Figure 38 Wire extended connection for 600/230 V Figure 39 Reducing Voltage for House Delivery iii

5 LIST OF APPENDICES (Presented in Part 6-3 of Volume 6) Appendix 1 Appendix 2 Introduction of LED Lighting Project Examples Appendix 2-1 Appendix 2-2 Appendix 2-3 Appendix 2-4 Sem Pai Micro Hydro Project Using Grass Root Grant Micro Hydro Project in Thale Oo Village Micro Hydro Projects in Kyauk Ye Oo and PaOh-Gawraka Village Micro Hydro Project in Hanpo Village Appendix 3 Design of Crossflow Appendix 3-1 Appendix 3-2 Design of Crossflow Turbine Blade Effect of Nozzle Shape on the Turbine Performance Appendix 4 Appendix 5 Line Connection Work for Village Distribution Line Cost for House Wiring iv

6 ABBREVIATIONS Organizations JICA MADB MEPE MPBANRDA MOC MOEP SPICL USDA VEC VPDC VWSDC Economics, Finance ATP WTP Japan International Cooperation Agency Myanma Agricultural Development Bank Myanma Electric Power Enterprise Ministry for Progress of Border Areas and National Races and Development Affairs Ministry of Cooperatives Ministry of Electric Power Sein Pann Industrial Production Co-operative Limited Union Solidarity and Development Association (an NGO) Village Electrification Committee Village Peace and Development Council Village Water Supply Distribution Committee Ability to Pay Willingness to Pay Unit kva kwh K US$ kilo Volt ampere kilo-watt-hour Currency unit of Myanmar (Kyat) Currency unit of USA (US dollar) Others BCS IPP NGO O&M RE SHS Battery Charging Station Independent Power Producer Non Governmental Organization Operation and Maintenance Rural Electrification Solar Home System Exchange Rates US$ 1.00 = Ks. 500 = Yen 120 (May 2001) unless otherwise specifically noted v

7 HOW TO USE DESIGN MANUAL - VILLAGE HYDROS Whom is Village Hydro Manual for? Design Manual - Village Hydro will serve those MEPE engineers who design and construct small electrification schemes with Village Hydro having an installed capacity of less than 50 kw. Design Manual - Village Hydro would be useful also to those people and organizations of the private sector who will support or undertake design and construction of electrification schemes with Village Hydro. What is Village Hydro? Village Hydro is defined as small hydro with an installed capacity of less than 50 kw to supply power to villagers mainly for lighting purpose. Village Hydro is manually operated to save the governor cost since the lighting load is rather stable and does not require automatic adjustment of the power output by the governor. Radio and small TV may also be powered by Village Hydro. However, it should not be intended to supply power to motors for cottage industry, irrigation pumps, heaters, etc. that consume big power. Switching-on or -off of these equipments will cause large and sudden changes in the load that the turbine cannot respond to and would cause undesirable and even harmful voltage drops or rise. The main concept of Village Hydro is to achieve village lighting on a self-help basis of low cost that would be affordable to the villagers. Low cost schemes are realized through minimizing the capital costs by employing various design concepts and implementing cost saving methods. For example, the weir does not necessarily have to be a permanent structure: the power supply may be stopped when intake weir is washed away by flooding and would be resumed after flooding by reconstruction of the weir. Similarly, the channel may be earth without lining nor channel cover. All the construction works are usually undertaken by villagers including production and transportation of materials such as sand and gravel, wooden poles for distribution lines, etc. What is Design Manual - Village Hydros? Design Manual - Village Hydro provides the basic technical notes and information required for the design and construction of Village Hydro. These include: Planning: demand estimate, determination of required generator output and turbine discharge, site selection, site investigations, and project layout; Design of civil works: layout of waterway system, intake, power canal, head tank, penstock, power house, and tailrace; Design of generating equipment: features of crossflow turbine type recommended for Village Hydro, type of generators, reference for coupling design, etc.; Design of distribution lines: size of conductor, distribution voltage, voltage drops. vi

8 Part III Design Manual - Village Hydros With a Village Hydro scheme with installed capacity of 50 kw, a village consisting of about 300 households can be supplied, assuming demand of 80 W per household for lighting purpose apart from lighting for public facilities. To fully harness the hydropower potential, it is important to have a good design of waterway and turbine-generator as well as adequate voltage and conductor size for transmission and distribution lines. The costs for the transmission and distribution lines would usually account for the largest part of the total capital costs for construction. 1. Introduction 1.1 Power Sources for Village Schemes Village Schemes are defined as small scale village electrification projects with installed capacity less than 50 kw with energy sources represented by: Village Hydro (<50 kw) Pico Hydro (<1 kw) Rice Husk and Wood Figure 1 Three Power Sources of Village Schemes Battery lighting with solar or wind power is an option for remote villages without such power potentials mentioned above -1- The Study on Introduction of Renewable Energies

9 BCS with Solar Cell or Wind Turbine Carry battery to BCS for charging every 4-5 days Battery charging at BCS Battery Battery Battery Community Hall/Library Solar Cell or Wind Turbine 20 W light Battery Home 1 8 W light Home 2 Home 3 Battery Battery 20 W light 20 W light Figure 2 Home and Community Hall Lighting with Solar/Wind-Energized Batteries However, the cost of the battery lighting system generally exceeds the Ability to Pay (ATP) of the villagers, and therefore could only be implemented with external financial support. Their technical aspects are studied and presented in Part 8-2 Solar and Wind Power, Volume 8 Supporting Report 3 and will not be presented in this Manual. The suitable power source for a certain Village Scheme should first be checked by use of the selection matrix shown below: No. Region Extension of Distribution Lines from National/Local Grids DHP Small & minihydro Village Hydro (Micro/Pico) Solar BCS MEPE and VEC Wind BCS Biomass gas engine 50-10,000 kw <50 kw kw kw kw 1 Mountain Regions with rice husk or sawdust 2 Delta and Paddy Cultivating Regions - on irrigation channel where wind prevails with rice husk 3 Coastal Regions with rice husk or sawdust 4 Remote and hardly accessible areas - with rice husk 5 Urban Areas including Suburbs Legend: This pattern means out of scope of the current study. to Shows level of potential for implementation. Biogas may be useful for lighting and cooking in those households in the border areas which are scattered in wide areas and, therefore, favor such individual system as for own home use rather than the distribution line-connected RE system. Figure 3 Framework for Preliminary Selection of Form of Renewable Energy by Location -2- The Study on Introduction of Renewable Energies

10 1.2 Village Schemes with Village Hydro The Village Schemes with Village Hydro is aimed to supply villages with demand of about 80 W per household for home lighting purposes. Village Hydro utilizes the hydropower potential available nearby the village, and the electricity produced will be distributed through low voltage distribution lines (230 V). 230 V overhead lines Power Station Home 80 W Home 80 W Home 80 W Home 80 W Figure 4 Typical Village Scheme In case there is a fair distance between the power plant site and the village, a low voltage transmission line of V becomes preferable in order to reduce transmission loss as shown below. 230 V overhead lines Power Station Trf V overhead lines Trf. Home 80 W Home 80 W Home 80 W Home 80 W Figure 5 Village Scheme with Power Station at Distant Location This Manual is prepared especially to realize Village Schemes with Village Hydro, but, demand estimate and distribution line planning explained in the Manual is also applicable to Village Schemes with rice husk gas engine. 1.3 Supports to Village Schemes The three types of support is available for the realization of Village Schemes as shown in the figure below. -3- The Study on Introduction of Renewable Energies

11 House -hold 1 House -hold 2 House -hold 3 House -hold 4 House -hold 5 House -hold 6 House -hold 7 Village Electrification Committee (VEC) or Village Electrification Cooperative (VEC) Institutional & technical supports Financial & technical supports Financial supports MEPE Township Office NGOs Experts/ Cooperatives Suppliers/ Contractors Bankers/ Micro- Creditors Figure 6 Supporters of Village Schemes The organizations that may be helpful to the Village Electrification Committee / Cooperative (VEC) are listed in Appendix 1-1 for reference. -4- The Study on Introduction of Renewable Energies

12 1.4 Procedure for Village Scheme Implementation The Village Scheme may be implemented following the procedure illustrated below. Consult MEPE Township Office Establish VEC Monitoring and advice by MEPE RE Section through Township Office s O&M by VEC Figure 7 Procedure for Village Scheme Implementation -5- The Study on Introduction of Renewable Energies

13 As the first step towards realization of the Village Scheme (VS), organization of the VS-preparatory Group is essential. The main tasks of the Group are: To contact MEPE Township Office for copy of Visual Guide as well as for institutional and technical supports; To contact and invite Expert/NGO for their site inspection, potential assessment, basic planning, and cost estimate (The cost of such Expert should be borne by the VS-preparatory Group.) To organize and establish VEC based on the plan and cost estimate. -6- The Study on Introduction of Renewable Energies

14 2. Investigation and Planning 2.1 Estimate of Electrification Demand and Required Power (1) Consumers and Power Demand Percentage share and unit demand of each consumer type may be assumed as shown in Table 1. Table 1 Basic Assumptions on Consumers and Unit Power Demand Share or nos. Fan/ Unit Users per household Lighting TV or village Heater Demand Domestic Remarks Type A Household with battery lighting 20% of total households Charge battery at commercial BCS of total Type B Household 60% households of total Type C Household 20% house- Type D Shops/ restaurants Public Primary School 1 Monastery/Community Hall Clinic 1 Streetlights 4 Business Battery Charging Station (BCS) 1 1 holds per 100 households per 100 households per 100 house- 20W x W x 3 200W x W x 5 200W x W x 1 40W x W x W x 1 40W x 15 holds per village > 40W x househouseholds per streetlight 200 W x W x ,000 1, W x Rice-mill, etc ditto - per light. 20 W lights may also be used. BCS on commercial basis may be operated with own With the basic assumptions above, the power demand of Village Scheme is estimated as presented in Table 2 for different villages sizes of 20 to 400 households. -7- The Study on Introduction of Renewable Energies

15 Table 2 Power Demand by Village Size Consume r Category Share or nos. per household or village Unit Demand Type A Type B Type C Type D Primary School Public Monastery/ Clinic Commun i-ty Hall Streetlights 20% 60% 20% of total households of total households Domestic of total households per 100 households per 100 households per 100 households per house- holds per village > 100 streetlight house- 0W 40W 260W 600W 1,000W 1,000W 600W 40W Assumed number of consumers Village Size (households) Number of Conumers by Category Total Number of Consumers Assumed demand Village Size (households) Demand by Consumer Category in kw Total Demand Pd kw (2) Required Generator Output The required generator output (P r ) to supply for the power demand derived above can be calculated by: P r = P d + w 1 + w 2-8- The Study on Introduction of Renewable Energies

16 = P d x ( ) = 1.3 P d where, P r : P d : w 1 : w 2 : required generator output, kw power demand, kw losses for transmission and distribution, assumed at w 1 = 20% of P d for a voltage drop by 10% reserved power, assumed at w 2 = 10% of P d The required generator output to meet the power demand in Table 2 is calculated by equation above and is presented in Table 3 as rounded figures. Table 3 Required Generator Capacity by Village Size Village Size Table 3 includes villages which require generator output exceeding 50 kw. Their scale is greater than targeted in this Manual and the Design Manual Small Hydro for > 50 kw may be utilized as reference, although it is recommended for the VS-preparatory Group to consult with experienced experts or organizations. The selected generator capacity in Table 3 can be approximated by the following equation for a village size of interest: P g = 0.15 N + 1 Total Demand Pd Required Generator Output Pr = 1.3 Pd Selected Generator Capacity Pg households kw kw kw where, P g : selected generator capacity, kw N: village size, number of households -9- The Study on Introduction of Renewable Energies

17 2.2 Required Head and Discharge for Village Hydro (1) Head and Discharge When a discharge of Q (m 3 /s) drops through a head of H (m), the work done per unit time is called the theoretical hydropower. Here, the discharge is defined as the amount of water flow used for power generation, and the head is defined as the height difference between intake and turbine outlet. Theoretical hydropower is calculated using the following equation. Head (m) Discharge (m 3 /s) Measurement of Discharge and Head P o = 9.8 H Q where, H: static head, m Q: discharge, m 3 /s The required discharge to obtain the required power is given for various heads in Table 4. (2) Required Generator Capacity and Theoretical Hydropower In reality, the theoretical hydropower cannot be produced because there are energy losses when converting theoretical hydropower into mechanical energy and then further into electrical energy. The relationship between the theoretical hydropower and the required generator capacity can be expressed as follows: P i = P o η G η T / (1 + m) = 0.57 P o where, P i : required generator capacity, kw P o : theoretical hydropower, kw η G : generator efficiency, assumed at 90% η T : turbine efficiency, assumed at 70% m: rate of other losses, assumed at 10% -10- The Study on Introduction of Renewable Energies

18 Table 4 Required Discharge by Available Head From Table 4 above, one can grasp the necessary set of required head and discharge to generate the required power. It is necessary to select the hydropower site that meets both the head and discharge and to measure these quantitatively as explained in the following sections. It is important to note that the discharge mentioned here refers to the dry season flow so to secure the power output even when the discharge decreases to the minimum normally in May to June. (3) Sample Calculation Village Size Total Demand Pd Required Generator Output Pr = 1.3 Pd Selected Generator Capacity Pg households kw kw kw A sample calculation is shown below for a village size of 200 households and a hydro potential site with a head of 10 m. Table 5 Sample Calculation of Required Generator Capacity and Discharge No. Description Value Remarks 1. Village size (N) 200 households to be counted 2. Electricity demand (P d ) 23 kw from Table 2 3. Selected generator capacity (P g ) 30 kw from Table 3 4. Available head (H) 10 m to be surveyed 5. Required discharge (Q) 0.54 m 3 /s from Table 4 If the village characteristics, demand and required power differ from those assumed and given in Tables 1 to 4, then estimate the generator capacity based on the surveyed actual demand and apply Table 4 with reference to the Selected Generator Capacity (P g ) neglecting Village Size (N) to obtain the discharge required to generate the given power with the available head The Study on Introduction of Renewable Energies

19 2.3 Investigation of Hydropower Potential (1) Survey of River Discharge In order to supply the required electric power constantly throughout the year, it is essential that the minimum river discharge in the dry season meets the requirements given in Table 4. In this context, it is important to measure the river discharge in the dry season, in the months of May and June in particular. Also, if there is an irrigation intake upstream of the Village Hydro site, the river discharge is likely to be reduced during the irrigation periods. It will, therefore, be required to check the river discharge at the intake site during the irrigation period from May to July. Output (kw) Water available for power generation Irrigation Supply Discharge Q (m 3 /s) Firm Power Output Irrigation Supply Not use for power generation Non - Operation Period Demand Q power Figure 8 Seasonal Changes of River Flow and Power Discharge On the other hand, it is also required to observe the flood water levels during the rainy season in order to know the possible maximum water level of floods and to protect the intake and waterway facilities from the floods accordingly. 1) Water Level Gauging Staff and Water Level Observation It is desirable to observe the river water levels throughout the year once the candidate hydropower site is identified and selected. The site for discharge measurement and water level observation shall be selected on a straight river stretch where water depth is uniform and flow conditions are stable. Also, the site should be on a uniform slope section of the river to avoid being affected by the change in riverbed level and river width due to scouring or sedimentation The Study on Introduction of Renewable Energies

20 Discharge Measurement by Current Meter Discharge is to be measured on a straight stretch of the river. A wooden staff with graduation preferably at 1 cm intervals shall be prepared and firmly placed vertically by concreting its bottom end deep into the ground at least 60 cm (2 feet) in depth. The zero level on the gauge shall be below the lowest water level expected in the dry season. To this end the gauge should be installed in the dry season. The graduated surface shall be faced in such as way so that the gauge reader easily read the water level on the gauge or clean the gauge surface. The water level observation should be made once a day at a fixed time, 7:00 a.m. for example. 2) Discharge Measurement by Float vm Float vs Q = c V A c : discharge coefficient V : velocity (m/s) A : flow area (m 2 ) Measurement by Float Discharge measurement by float shall be carried out as follows: -13- The Study on Introduction of Renewable Energies

21 A B Section I Section II Section III L/2 L/2 L Figure 9 Discharge Measurement by Float a) To select point A for dropping a float for the measurement (Section II in Figure 9 above may be located at around the water level gauging staff if already installed and point A upstream there from); b) To determine point B, L m downstream of point A; c) River cross section at point A is named as Section I, at center between points A and B as Section II, and at point B as Section III. Divide the river width into n uniform strips for each Section and measure water depth at center of each strip for all the 3 Sections. Here, n should be 2 at the minimum. d) To obtain the average section area A among the 3 sections by the following equations: A = A I = A II = A III = A I + A II + A 3 III WI (d I1 + KK + d n I n WII (d II1 + KK + d n ) II n WIII (d III1 + KK + d n ) III n ) e) To measure by stopwatch the time from dropping a float at point A till when the float passes the point B; -14- The Study on Introduction of Renewable Energies

22 f) To calculate the average flow velocity by the following equation: V i = where, L t i V i : flow velocity at i-th measurement, m/s L: distance between points A and B, m t i : arrival time of float from points A to B, second The velocity V i shall be measured for 10 times and their average shall be treated as the average flow velocity of one discharge measurement. g) The river discharge can be obtained by the following equation: Q = c V A where, Q: river discharge, m 3 /s V: average flow discharge (m/s) c: discharge coefficient c = 0.85 for concrete channel 0.80 for smooth flow 0.65 for shallow flow The water level observation may be made by installing a gauging staff at around Section II. Attention is needed to protect the gauge from damage by floods and flowing debris. It is also possible to place a graduated staff on the rigid rock surface under the water upon each measurement. In this case, the position to place the gauge shall be clearly marked for its easy identification at the next measurement. The discharge measurement results thus obtained shall be compiled into figure and table as shown in Figure The Study on Introduction of Renewable Energies

23 HQ Curve Gauge Height (m) Discharge (m3/s) Figure 10 H-Q Curve 3) Discharge Measurement by Current Meter 0.6 d Current Meter v 0.6 Q = V 0.6 A V 0.6 : velocity at 60% depth from surface (m/s) A : flow area (m 2 ) Velocity Measurement by Current Meter Discharge measurement using current meter is made selecting one section beside the gauging staff. Depth and flow area measurement shall be carried out in accordance with the similar method to that for float measurement. Velocity measurement can be made by one point method at 0.6 d (60% of the depth from the surface). If the river width is wide, the velocity measurement shall be made at center of each strip (refer to Figure 9 for strip). In this case, the discharge can be calculated by the following equation: Q = Q 1 + K K + Q n -16- The Study on Introduction of Renewable Energies

24 Q i = W n di V i where, Q: discharge, m 3 /s Q i : discharge in the i-th strip, m 3 /s W: river width, m n: number of strips, minimum 2 d i : depth at center of i-th strip, m V i : flow velocity at a depth of 0.6 d i on the center of i-th strip, m/s It is essential to check if the current meter has been calibrated prior to the measurement. As a general rule, the current meter should be calibrated once a year in order to obtain reliable velocity. Old current meter without calibration shall not be used. In such case, float measurements would give more dependable results. Current meter calibration could be executed at the laboratory of the Irrigation Department. (2) Survey of Head The gross head is defined as the difference in the river water levels at the intake site and at outfall site where the turbine discharge will be released to the river. The head can be measured by simple and less-costly methods as described below: 1) Survey Method on Gentle Slope A water tube/hose filled with water is placed as shown in Figure 11. The hose may preferably be transparent so that the water level inside the hose is visible. Transparent hose with water h2 dh h1 L Figure 11 Leveling with Water Hose Both the ends of the hose shall be kept nearly at the same level by fixing to a rod/stand bar. If water spilt and is in short, add water. Measure the -17- The Study on Introduction of Renewable Energies

25 height from the water level to the ground at both the ends. Measure the distance between the two ends if the slope is required. The head and slope can be calculated by the following equations: dh = h 2 h 1 I = dh L where, dh: height difference, m h 1 : height at unknown point, m h 2 : height at base point, m I: slope of the ground surface L: distance between the two points, m If the distance L is too long to measure by the available hose in one time, repeat the same procedure until arriving at the desired place. 2) Survey Methods on Steep Slope The method on the gentle slope could be applied also on the steep slope by repeating the procedure. In that case, two sets of movable stand should be provided to fix the two pipe ends. The second option is to measure the height difference using a carpenter s level and timber of 2 x 1 x 6 feet long. Height difference h i shall be measured progressively to arrive at destination. The gross head can be obtained by summing up h i for i = 1 to n-step. Hg Y Xn hn Measurement of Head Using Carpenter's Level X2 X1 h X Level Measurement of Head using Carpenter s Level h -18- The Study on Introduction of Renewable Energies

26 The third option is to use a pressure meter as shown in the figure to the right. Y Plastic Tube filled with water Hg Presure Gauge Measurement of Head Using Pressure Gauge X Measurement of Head using Pressure Gauge The fourth option is to use a combination of a pocket distance meter and a hand level (or clinometer or pocket compass). An inclined length is measured by the pocket distance meter while the horizontal angle θ is measured by the hand level. The height difference can be give by the following equation: H = L sin θ H h Measurement of Head using Distance Meter and Hand Level L θ h where, H: height difference between the two points, m L: inclined distance between the two points, m θ: horizontal angle, degree In this case, the two points are required to be visible to each other. The angle measurement should be made by targeting the head of a man standing on the objective point. This is to have the same height of the observer s eye level above the ground for the accuracy. The distance measurement should also be made using a reflecting board of about 1 foot square The Study on Introduction of Renewable Energies

27 GPS to measure coordinates & altitude Distance Meter Clinometer Portable Compass Tools for Measurement of Head (3) Topographic Survey and Slope Stability Investigation A typical layout of Village Hydro is shown in the figure (right). The water taken at the Intake will be guided to a Power Canal, which has a gentle slope to minimize the loss of head. The water will then rush down in Penstock which is usually placed on a steep slope to shorten the expensive Penstock length. Head Tank Penstock Power canal Powerhouse Tailrace Power (kw) = (5 ~ 7) Q H Discharge Q (m 3 /s) Intake General Layout of Power Facilities Head H (m) Efficiency η = 0.5~0.7 It is important to select the site where topography is suitable for such layout. In the case of Village Hydro, the detailed topography cannot be read and identified on a topographic map at a scale of 1:50,000. Accordingly, site reconnaissance and topographic survey on site are essential and should be performed repeatedly to well confirm the head in particular. Since the Power Canal will usually pass on mountain slopes, it would be subject to potential slope failure. It is important to have test pitting in such places to confirm the foundation conditions and slope stability The Study on Introduction of Renewable Energies

28 3. Basic Design of Civil Structures 3.1 Layout of Waterway System As illustrated below, typical Village Scheme consists of the following components: Intake Weir: to secure necessary water level to guide water to Power Canal. This may be omitted depending on the site conditions; Intake Gate: to take necessary water and block flood water and flowing debris; Power Canal: to carry water to Head Tank; Head Tank: to change the flow condition from free flow in Power Canal to pressure flow in Penstock; Penstock: to convey the pressured flow to Turbine; Powerhouse: to accommodate Turbine and Generator; Tailrace: to return the flow back to the river. Here, the term flow has the same meaning with discharge. It is the flowing water of river, Intake, Power Canal, Head Tank, Penstock, Turbine, and Tailrace. The maximum discharge adopted for design of waterway (Power Canal and Penstock) and Turbine is referred to as Design Discharge. Power Canal Head Tank Penstock Powerhouse General Layout -21- The Study on Introduction of Renewable Energies

29 Weir Intake Power Canal Head Tank Penstock Powerhouse Tailrace Trashracks Intake Gate Spillway Trashracks Sand Drain Gate Sand Drain Gate Anchor Block General Profile of Waterway TWL As may be seen from the waterway profile above, even if the Penstock discharge is stopped by Guidevane of Turbine or clogging of Penstock or any other cause, the flow in Power Canal will continue to flow down towards Head Tank. The flow will spill out from Spillway of Head Tank. The Spillway should have a Chuteway to safely carry the flow back to the river without causing channel erosion due to high speed flow. Another option to cope with such situation above is to raise the side walls of both the Power Canal and Head Tank to a level well higher than the Intake water level. With such profile design of the waterway, the flow can be confined within the Power Canal and Head Tank without causing spilling. In this case, the Spillway of Head Tank and its Chuteway down to the river can be omitted. A fused spillway (made of soil embankment with its crest level at the Intake water level) may be provided downstream of Intake so as to spill the excess water and keep the water level in Power Canal around design Intake water level. Presented right is a sample layout utilizing an existing river crossing structure as Intake Weir and omitting Power Canal. Omission of canal, and utilization of existing structures -22- The Study on Introduction of Renewable Energies

30 3.2 Basic Dimensions of Waterway System Table 7 presents standard basic dimensions of Power Canal, Head Tank and Penstock of Village Hydro for various combinations of available head and design discharge. Symbols in Table 7 are defined as: Q: design discharge of the waterway system, m 3 /s B PC : H PC : A HT : D PS : width of stone masonry Power Canal with vertical side walls, m normal water depth in earth Power Canal when flowing at a gradient of 1/1,500, m minimum flow area of Head Tank, m diameter of Penstock pipe, m Earth Canal Stone Masonry Canal The minimum flow area (that is, economic section of a free flow channel in view of excavation cost) of a trapezoidal section shown above for the Design Discharge Q can be given by the following equation: θ B = 2 H tan 2 = 2 H for vertical side walls (θ = 90 o ) where, B: width of channel at its bottom, m H: water depth of the flow; m θ : angle between side wall and horizontal plane, degree The depth of normal flow can be given by solving the following equation: V = R = 1 R 2/3 I 1/2 n A S -23- The Study on Introduction of Renewable Energies

31 = BH B + 2H for rectangular channel with vertical side walls where, V: flow velocity, m/s n: Manning s coefficient of roughness R: hydraulic radius, m I: hydraulic gradient A: flow area, m 2 S: wet length of flow area, m B: width of channel at its bottom, m H: water depth of the flow; m The diameter of Penstock pipe can be given by the following empirical formula: D ps = 1/ H ( P / H ) 3 / 7 where, D PS : diameter of Penstock pipe, m Q: design discharge, m 3 /s H: maximum static head, m A sample calculation is shown below for a village size of 200 households and a hydro potential site with a head of 10 m: Table 6 Sample Calculation of Waterway Dimensions No. Description Value Remarks 1. Q 0.27 m 3 /s 2. B PC 0.98 m 3. H PC 0.49 m n = 0.018, I = 1/1,500, normal 4. A HT 2.7 m 2 5. D PS 0.51 m Source: Calculation by JICA Study Team flow depth satisfies B PC = 2H PC When the village characteristics, demand and required power are different from those assumed and given in Tables 1 to 4, then estimate the generator capacity based on the surveyed actual demand and apply Table 7 with reference to the Selected Generator Capacity neglecting Village Size to obtain the basic dimensions of the waterway system. Marginal height is needed for canal in addition to the water depth H PC (m). Penstock diameter should be selected from standard size that is available in the market with reference the Table The Study on Introduction of Renewable Energies

32 Table 7 Basic Dimensions of Waterway System ( I = 1/1500, n= 0.018) Village Size Selected Generator Capacity Required Theoretical Potential households kw kw Q (m 3 /s) B PC (m) H PC (m) A HT (m 2 ) D PS (m) Q (m 3 /s) B PC (m) H PC (m) A HT (m 2 ) D PS (m) Q (m 3 /s) B PC (m) H PC (m) A HT (m 2 ) D PS (m) Q (m 3 /s) B PC (m) H PC (m) A HT (m 2 ) D PS (m) Q (m 3 /s) B PC (m) H PC (m) A HT (m 2 ) D PS (m) Q (m 3 /s) B PC (m) H PC (m) A HT (m 2 ) D PS (m) Q (m 3 /s) B PC (m) H PC (m) A HT (m 2 ) D PS (m) Q (m 3 /s) B PC (m) H PC (m) A HT (m 2 ) D PS (m) Q (m 3 /s) B PC (m) H PC (m) A HT (m 2 ) D PS (m) Availablle Head (m) Penstock diameter may be selected from the size available in the market and nearest to D ps above The Study on Introduction of Renewable Energies

33 3.3 Intake No. Description Remarks 1. Hydraulic Functions To secure taking design discharge from river To minimize inflow of sediment and flowing debris (leaves) into the headrace channel Intake Gate to block flood flow entering into Power Canal and to avoid the overflow from Power Canal that will cause catastrophic erosion and damage to the slope and canal foundation. Gate width & height Selection of appropriate intake site, provision of skimmer wall Intake gate with sufficient height and strength to be provided. 2. Structural Requirements Intake Gate to withstand against flooding while Intake Weir can be repaired after the flooding season is over Site selection like sample at Tha Le Oo 3. Issues Method for determining the normal water levels of Intake and Head Tank Criteria for determining the gate height and width Uniform flow depth of Power Canal Investigation of flood levels at Intake site Samples: Sample of using existing structure Existing stone weir is used as intake. Sample of utilizing natural topography Utilizing waterfalls for stable riverbed, low flood level, less sediment deposits, blocking debris flow by bamboo skimmer. Tha Le Oo -26- The Study on Introduction of Renewable Energies

34 Sample of weir by gabion Sample of weir by sandbags Sample of concrete weir A scheme built with grass root grant from Japan. The level of design and construction is of mini-hydro class and is beyond this Manual for Village Scheme. Sampai Source:APT (Aung Pyi Tun Construction Ltd.) Flood flow over intake weir The concrete weir withstands flooding. Sampai Source:ATP (Aung Pyi Tun Construction Ltd.) Intake Weir Re-building would be needed after every rainy season. Use of sandbag may better. Sample of Intake Trashracks Primary racks to avoid floating trees combined with secondary racks to avoid tree leaves from entering The Study on Introduction of Renewable Energies

35 Spillway Trashracks & Skimmer Wall Intake Gate Sand Drain Gate Skimmer wall to avoid inflow of excessive water and debris Wooden Hand-pull Gate Wooden Hand-pull Gate Just start opening. The wooden gate well functions. Tha Le Oo. Steel Hand-pull Gate -28- The Study on Introduction of Renewable Energies

36 3.4 Power Canal No. Description Remarks 1. Hydraulic Functions To carry the design discharge to Head Tank without causing overflow from Power Canal; To bypass the excess water, if any, through Spillway; or To confine all the water within Power Canal by raising the side walls in case Canal flow is blocked; standard hydraulic gradient at or even gentler than 1:1,000 to reduce flow velocity (10 cm drop in water level in 100 m long channel.) Spillway and Chuteway needed at Head Tank. 3 possible cases: Turbine Guidevane is closed; Penstock is clogged; Canal is filled and blocked by sliding soils from side slopes. 2. Hydraulic Requirements Flow velocity to be slower than 0.3 m/s so as not to cause channel erosion. Preferably to provide a fused spillway section downstream of Intake, in addition to the raised side walls in the option above. Slow flow velocity is preferable. Chuteway can be shorter compared to that of Spillway at Head Tank. 3. Issues Sedimentation in Power Canal Criteria for determining height and width of the channel Criteria for determining crest elevation of the side walls of Power Canal Canal to be periodically cleared of sediment deposits See sample. A freeboard of 30 cm (1 foot) is preferable for -29- The Study on Introduction of Renewable Energies

37 Criteria for determining crest elevation and length of the side-overflow spillway earth canal. Overflow crest level can be at the Intake water level. Crest level can be given by: Q L = H L: crest length, m Q: discharge, m 3 /s H: overflow depth = 0.10 m Samples: Masonry Canal Properly designed lined canal reduces the canal size and the excavation volume required to convey the same discharge Sampai Source: APT Brick masonry canal Power canal under construction Tha Le Oo -30- The Study on Introduction of Renewable Energies

38 Earth canal with bypass spillway Sliding of slope by overflow Debris Stone-pitched canal, Hanpo Sliding can be induced by overflow from a canal in which debris entered and blocked the canal flow. Slope failure eroded by overflow water from the power canal The Study on Introduction of Renewable Energies

39 B Side spillway to overflow excessive inflow. Hoping Side Spillway Side-overflow spillway. Source: APT Sampai Sample design of Power Canal : Discharge Q = 0.2 m 3 /s, canal slope i = 1/1,000, width B = 0.8 m roughness coefficient n = (stone masonry lining) Water depth D = 0.45 m, velocity V = 0.56 m/s Canal size = 0.8 m (width) x 0.6 m (depth) 15 cm Q = 0.2 m 3 /s i = 1/1,000 v = 0.56 m/s 45 cm 15 cm 15 cm 80 cm 15 cm -32- The Study on Introduction of Renewable Energies

40 3.5 Headtank No. Description Remarks 1. Hydraulic Functions To materialize smooth transition for the water from free flow in Power Canal to the pressure flow in Penstock; To trap flowing debris, leaves by trashracks To deposit sediments (sill elevation of penstock inlet must be higher than floor by 30 cm); To release excess water from Spillway 2. Structural Requirements Width of Head Tank to be determined to have flow velocity slower than 0.20 m/s; Total water surface area of Head Tank and Power Canal to be more than 5-10 x Q; Sand flushing gate and chuteway to be preferably provided. Adequate water surface area is needed to adjust difference in the discharge of Canal and Penstock Trashracks at low flow velocity Periodical sand flushing/clearing is needed. Spillway can be omitted when side walls of Power Canal and Head Tank are raised to confine water within the waterway. Width of Head Tank V = Q < 0.20 m/s BH Q: discharge, m 3 /s B: width, m H: depth, m Length of Head Tank L > 3 B 3. Issues Criteria for determining the normal water level (= crest elevation of the spillway) of Head Tank To be equal to the Intake water level The Study on Introduction of Renewable Energies

41 Samples: Head Tank & Bamboo Trashracks Sand Drain Gate at Head Tank Head Tank with Spillway Head Tank with trashracks Head Tank too small, no trashracks, and floating debris can clog the penstock inlet. Trashracks on Power Canal, needs improvement -34- The Study on Introduction of Renewable Energies

42 ] No spillway and side walls are not high enough to avoid water spilling. 3.6 Penstock No. Description Remarks 1. Hydraulic Functions To carry the pressured water to turbine. 2. Structural Requirements The flow in the Penstock pipe should always be pressured flow, that is, the Head Tank water level should always be above the Penstock inlet sill by 2D (referred to as the Intake Submergence) Diameter of Penstock can be determined by: D ps = 1/ H ( P / H ) 3 / 7 3. Issues To be rigid enough and anchored to avoid vibration Hydraulic force operates upon bend Penstock slope to be protected and drains provided to avoid possible erosion by rainwater refer to Design Manual Small Hydro -35- The Study on Introduction of Renewable Energies

43 Samples: After completion. Hampo Penstock is well fixated with anchor block. Hampo Source: RDHG (Rural Development and Hydroelectric Implementation Group) Anchor block of penstock Under construction. Pan Pung Source: RDHG Penstock on masonry slopes Penstock is placed on stone masonry to adjust to site topography. Mine Pon Source: RDHG -36- The Study on Introduction of Renewable Energies

44 Penstock under installation, Naung Bo. Source: RDHG Penstock & Powerhouse under construction Source: RDHG Soung Pho Source: RDHG Penstock & Distribution Lines -37- The Study on Introduction of Renewable Energies

45 Tha Le Oo Sample of protection works of Penstock slopes by stone pitching 3.7 Powerhouse No. Description Remarks 1. Functions To protect generating equipment from rainwater, etc. To provide shelters for operators 2. Structural Requirements 3. Issues To be free from flooding To have space, lighting, toilet, and footpath for operators Criteria for determining the turbine center elevation The level free from flood submergence The Study on Introduction of Renewable Energies

46 Samples: 2 story Powerhouse Upper floor for operator and lower floor for turbine & generator, Tha Le Oo Powerhouse and penstock Under construction, Sampai Source: APT Level of powerhouse Powerhouse well above the flood water level, Kyae Powerhouse of Pico Hydro -39- The Study on Introduction of Renewable Energies

47 3.8 Tailrace No. Description Remarks 1. Hydraulic Functions To guide the water back to the river. 2. Requirements 3. Issues Preferably not to receive backwater effect from the river. Criteria for determining the width and bottom elevation of Tailrace See photos below, flow falling into river Uniform flow depth above the flood level at the river outlet. Samples: Tailrace channel excavated to utilize the head remaining between turbine and river. Tha Le Oo. Source: RDHG Tailrace under construction, Tha Le Oo Source: RDHG No power discharge, tailrace (left side) is dry and above river water level.. Power discharge is falling down into river (right) with control section -40- The Study on Introduction of Renewable Energies

48 4. Design of Hydro-mechanical and Electrical Equipment 4.1 Planning of Turbine, Generator, Transformer, and Distribution Lines A Village Hydro scheme needs an appropriate site for hydropower within a certain distance of the village to provide a the stable electricity supply to customers in the village. Basically, Village Hydro is similar to the general power supply business, but at a very small scale and with many issues that need considerations when planning equipment. The main requirements are briefly described below: (1) Easy operation As the generating capacity of a Village Hydro scheme is small, it is difficult to gain an expert for operation at a high level of technology. It must be designed so that it can be operated easily and safely by villagers. However, the application of an automatic operation system would be impractical because of the high capital cost and difficult maintenance. Thus, careful consideration should be given to the load characteristics, discharge fluctuation, and so forth, and equipment that has characteristics of small fluctuation in output without special adjustment should be selected. (2) Durable There are many types of hydropower equipment. In selecting the equipment, priority should be given to simplicity and durability over efficiency and other functions. Equipment with simple structure tends to be easy to maintain and repair. (3) High availability It will be advantageous to find turbines, generators, etc. from local manufacturers operating nearby the village. Future repair services can then be easily obtained. (4) Small voltage fluctuation If the voltage fluctuation is large, light brightness also fluctuates, and sometimes the lights cannot be turned on or appliances can be damaged. The cause of voltage fluctuation sometimes depends on the characteristics of the generator, but in most cases it comes from insufficient capacity of in the distribution lines The Study on Introduction of Renewable Energies

49 Construction budget may be limited, but a Village Scheme should be sustainable and stable. It should be planned to supply stable and quality electricity, with consideration also to the future demand increase. (5) No accident of electricity leakage and electrocution Many of Village Hydro are designed with voltages lower than 700 V, and in many cases sufficient precautions are not taken in operation and maintenance. However, serious accident can happen by electricity leakage, electrocution, etc., even at a low voltage. Careless accident should be avoided by giving sufficient attention even for routine work. 4.2 Turbines Village Hydro would be applied to villages of households as shown in Table 7. Village Hydro utilizes a head range of about 3-30 m and a discharge range of about m 3 /s. The types of turbine applicable for these head and discharge ranges are shown in Figure 12. Source: SCO (Sudo Consulting Office) Figure 12 Application Range of Turbine Type for Village Hydro (1) Horizontal shaft Pelton Turbine This is a turbine widely used for high head conditions The Study on Introduction of Renewable Energies

50 The structure is simple and durable. It is applied to comparatively large outputs and a head higher than 30 m. On the other hand, they are difficult to manufacture, and only specialized manufacturers can produce them. They tend to be expensive and difficult to purchase locally, and therefore have not been popular for Village Hydro. (2) Vertical shaft Turgo-Impulse Turbine Turgo-impulse Turbines used to exclusively have a horizontal axis that could operate under a high head range after the Pelton turbine. Modified versions with a vertical axis have been used for low head conditions and small discharges. This turbine has not been so popular because of possible vibration due to its structure and difficulty in manufacturing the runner. (3) Vertical shaft Propeller Turbine This turbine is applied to locations with a low head and comparatively large discharge. Propeller Turbines are applied to obtain high revolution speed. This is a so-called Package Type Turbine with a vertical shaft to minimize the installation area. They are housed in a cabinet, which enables field installation without shelter. Control panel, AVR, dummy-load governor, circuit breaker etc. are equipped as a package. It would be the most suitable type for small village except that, from the manufacturing point of view, difficulty in procuring a vertical shaft generator is a disadvantage The Study on Introduction of Renewable Energies

51 Figure 13 Vertical shaft Propellar Turbine Figure 14 Package-type Micro Turbine Generator (4) Vertical shaft Pico Hydro This is a further simplified type of the Package Type system. As shown in Figure 15, the turbine and generator are connected by a long stem, and a shaft inside the stem transmits the rotation of the turbine runner to a generator rotator. The output is W. This type has been adopted in Vietnam, Laos, and so on for private use. The generating capacity would be insufficient for Village Hydro, but they are useful for isolated residences with a stream nearby. Figure 15 Pico Hydro -44- The Study on Introduction of Renewable Energies

52 (5) Crossflow Turbine The Crossflow Turbine was developed by Osburger Co. by improving the Banki turbine. The runner width was increased relative to the runner diameter in order to apply a low head and large discharge. Figure 16 Flow in Crossflow Turbine The Banki turbine was developed as an impulse turbine for use with relatively high head and small discharge. In a Pelton turbine, which is the typical turbine used for this range of head and discharge, the discharge enters the runner from its circumferential direction and leaves the runner at a right angle to the inflow direction. In the Banki turbine, the discharge enters the runner from its circumferential direction, passes inside the runner, and again passes through the runner blades toward the opposite direction before leaving the runner as shown in Figure 16. Osburger named the turnbine Crossflow Turbine as their brand-name from this flow characteristic. Owing to the following features of the Crossflow turbine, many manufacturers now produce this type of turbine by remodeling them to suit the conditions where they are installed: the runner can be easily made by welding; the structure of the turbine is simple and easy to handle; manufacturing cost is low; since it has been modified from the Banki turbine, it is easy to modify aganin and remodel. All turbines in which water flows against the runner similar to Figure 16 are called Clossflow Turbine. Hereinafter in this Manual, the turbines with such water flow inside the runner are referred to as Crossflow-type to distinguish them from the Osburger Clossflow Turbine The Study on Introduction of Renewable Energies

53 4.3 Turbine Manufacturing for Village Hydro Crossflow-type Turbines are easy to manufacture and handle, which makes them the most suitable turbine for Village Hydro. Many types with various ideas and characteristics exist. (1) Shape and Dimensions of Runner Runner shape and dimensions are important in many types of turbines. The dimensions consist of the outer diameter and the width of the runner as shown in Figure 17. Figure 17 Outer Appearance of Runner Structure If the runner is wide, a supporting board is placed to ensure sufficient strength of the blade. The width, b, of water passage between the supporting board/disks should be smaller than the runner radius. In this case, the disks are welded to each blade and shaft, while the supporting board is welded only to the blade but not to the shaft. Table 8 shows the outer diameter D, optimum revolution speed N, effective flow width B, and shaft diameter d s of runners applicable to various combinations of village size and available head The Study on Introduction of Renewable Energies

54 Table 8 Basic Dimensions of Crossflow-type Runner for Village Hydro Village size Generator output Turbine Dimension by Avalilable Head (m) Households kw D (mm N (min -1 ) B (m) d s (mmφ) D (mm N (min -1 ) B (m) d s (mmφ) D (mm N (min -1 ) B (m) d s (mmφ) D (mm N (min -1 ) B (m) d s (mmφ) D (mm N (min -1 ) B (m) d s (mmφ) D (mm N (min -1 ) B (m) d s (mmφ) D (mm N (min -1 ) B (m) d s (mmφ) D (mm N (min -1 ) B (m) d s (mmφ) D (mm N (min -1 ) B (m) d s (mmφ) The Study on Introduction of Renewable Energies

55 (2) Dimensions of Runner Blade Table 9 Nos. of Blade and Pitch Nos. of Blade N Chord Length of Pitch D D D D D Note: N<26 cannot be adopted. Source: SCO Figure 18 Dimensions of Runner Blade Outer diameter D of the runner is the basic parameter for design. The diameter of the curvature of the blade stands indicates the inner surface of the blade. Table 10 Runner Diameter and Blade Thickness Runner diameter mm Thickness of blade mm Source: SCO -48- The Study on Introduction of Renewable Energies

56 (3) Dimension of Casing 1) Crossflow Source: SCO Figure 19 Casing Dimension of Clossflow-type Turbine Overshot Banki Turbine Source: SCO Figure 20 Casing Dimension of Overshot Banki Turbine -49- The Study on Introduction of Renewable Energies

57 3) Undershot Banki Turbine Source: SCO Figure 21 Casing Dimension of Undershot Banki Turbine 4) Nozzle for Banki Turbine Source: SCO Figure 22 Nozzle Dimension of Banki Turbine (3) Examples of application of Crossflow-type turbine 1) Types of Crossflow-type turbine Crossflow-type turbines are categorized into three types as shown in Figures The Study on Introduction of Renewable Energies

58 The Crossflow Type Turbine in Figure 19 is the most orthodox one. The efficiency is high and operation is stable. However, it needs sophisticated processing machines for manufacturing. It has been manufactured at well-equipped machinery workshops. Thus, the cost is high and it would be difficult to procure. The type shown in Figure 20 is applied for water flow guided by an ordinary penstock. It may also be used at relatively low head site such as drop-structures of irrigation canals as shown in Figure 23. Figure 23 Application of Overshot Crossflow Turbine to Drop-Structures Since the undershot Crossflow turbine in Figure 21 can utilize a little more head than the overshot Crossflow turbine, it is applied to runners having large diameter. Figure 23 is an example of applying this turbine type to a low head site. On installation of these turbines, it is needed to secure a space between the tailrace water level and the bottom level of the runner or to design the slope of the tailrace steeper than 1/10 so that the turbine discharge released from the runner will not touch the lower surface of the runner. This type of turbine could be installed inside a canal by providing a partition wall The Study on Introduction of Renewable Energies

59 A protection cover prevents some of the water discharged from the runner from running upward and flushing. It also protects the runner when the upstream water level of the canal increases rapidly due to torrential rainstorm and the water spills over the partition wall Figure 24 Example of Application of Undershot Crossflow to Canal 2) Application to Village Hydro Village size Table 11 Application of Crossflow-type Turbine Power output Miscellaneous parts of turbines 1) Shaft Bearings Rolling bearings are used for the turbine shaft m m m m m m m Clossflow turbine Overshot type Undershot type Among the rolling bearings, ball bearings are applicable to turbines for Village Hydro since the load for such turbines is small. It would be convenient to use pillow blocks available in the market The Study on Introduction of Renewable Energies

60 Table 12 Dimension Table of Pillow Block Type Bearing Type Shaft Shaft Main dimension Name of Type diameter diameter h a e b S 1 S 2 g W j Bi n L attaching bolt UCP UKP M14 UCP UKP M14 UCP UKP M14 UCP UKP M14 UCP UKP M16 UCP UKP M16 UCP UKP M16 UCP UKP M20 UCP UKP M20 UCP M22 UCP UKP M22 UCP UKP M22 UCP UKP M27 UCP UKP M27 UCP UKP M30 UCP UKP M30 UCP M30 UCP UKP M33 UCP UKP M33 UCP UKP M33 UCP UKP M33 Grease nipple is 1/4-28UNF for diameter number of bearing lower than 08 and PT1/8 for higher than 09. Grease cotton packing Casing 2) Ground packing Ground packing is applied to prevent water leakages at piercing parts such as main shaft and guidevane shaft. The right figure shows the structure of ground packing. Grease cotton packing is used as a packing material. Packing stopper Stuffing box Figure 25 Structure of Ground Packing Shaft -53- The Study on Introduction of Renewable Energies

61 As the water pressure does not work on the main shaft part in the case of Clossflow-type Turbine, it would not be a problem if a simple water separator was used. However, ground packing is needed for the guide vane shaft part. 3) Oil seal When a ready-made oil seal is used in place of ground packing, the structure can be simple and a good sealing effect is obtained. Type Symble Refference figure Outer rubber spring circle with Outer circle rubber withput spring Outer circle rubber with spring and dust cover S G D There are many types of oil seals from various manufacturers. Basically, these are categorized into three types as shown in Figure 26. For the application to turbines, S type is recommended for the main shaft and G type for the guidevane shaft. Table 13 presents the dimensions of these oil seals. It is noted that there are detailed standards of the design to install the oil seals, therefore it is indispensable to have a full knowledge of the manufacturers catalogues, etc. Figure 26 Types of Oil Seal -54- The Study on Introduction of Renewable Energies

62 S Table 13 Oil Seal Dimensions G Dimension Table for S-type Oil Seal Inner diameter (called) Outer diameter Width Dimension Table for G-type Oil Seal Inner diameter (called) Outer diameter Width d D B d D B The Study on Introduction of Renewable Energies

63 4.4 Generators Alternating current (AC) generators are mainly used for Village Hydro. The types are shown in Table 14. Type Synchronous generator Induction generator No. of phase 3 phases Single phases 3 phases Table 14 Types of Generator Capacity kva Voltage V Revolution speed min- 1 Type of excitation or 1,500 or 1,000 Self-excitation ,500 Self-excitation (Compound winding) ,500 Condenser The three-phase synchronous AC generator has three coils arranged by shifting each phase by 120 against the magnetic pole. It will generate the voltage wave form shown in Figure Time (A) R-S S-T T-R R S Voltage 0 Three phase T - U + U-V Time (B) V Voltage 0 Single phase - T Figure 27 Alternating Current of Three-phase and Single Phase Three-phase generators are used for most large capacity generators since they are suitable for rotating an electric motor and parallel operation with other units The Study on Introduction of Renewable Energies

64 In Village Hydro, which usually has no load from electric motors, it is not required to adopt a three-phase AC generator. If the generator capacity is large and there is no choice but to use a three-phase alternator, the load on each phase should be balanced. Single phase generators have a simple structure and are suitable for capacities of less than 20 kw. Single phase generators with compound winding characteristics have small voltage drops during load increase and best suit Village Hydros that will be operated in isolation from the MEPE grid. There have been instances where a small induction generators of less than several kw has been used adapting excitation of an induction motor with condensers. (1) Three-phase AC synchronous generator This is the most common generator and is employed in a wide range of capacities. It rotates an excitation coil (rotor) and produces electric output from the stator. It is referred to as Revolving Magnetic Field type generator. Principle and characteristics of generators W n G 3 V The output voltage is in proportion to the product of the revolution speed, n, and excitation current, i f. Brush (A) i f D RH V = k n i f (1) Figure 28 shows the relationship between the excitation current and generated voltage. When V V 0 V 1 m 0 m 1 m' N 0 N' the revolution speed is constant, it is possible to change the voltage only by excitation current. v 0 0 (B) i f1 ' i f0 i f0 ' i f Figure 28 Principle and characteristics of AC generator -57- The Study on Introduction of Renewable Energies

65 Excitation needs direct current (DC). For small generators, a rectifier, D in Figure 28, converts the self-generated AC voltage to DC, which is supplied to an excitation coil through the brush sliding with a slip ring that rotates together with a shaft. This system is called self-excitation. The excitation current can be changed by adjusting the rheostat RH in the excitation circuit. If the resistance of RH is set constant, the excitation current i f is proportional to the voltage given to the excitation circuit, that is, the generator voltage. The characteristic is described as a straight line O-m o in Figure 28. When N 0 is the rated revolution speed and V 0 is the rated voltage, the curve described as N 0 passes through m o and is called the no-load saturation characteristic of the generator. For an arbitrary revolution speed N, the voltage will change along the curve that passes through m and m 1 in accordance with the change in i f. It is obvious from Equation (1) that to obtain the rated voltage, the excitation current will be increased up to i f0 by reducing the resistance of RH. If the resistance RH is kept equal to N 0, the relationship between voltage and excitation current will be a straight line O-m o ; the excitation current will decrease to i f1, and terminal voltage will decrease to V 1 The generator voltage will also decrease along with load increase even if the revolution speed is kept constant. AVR is equipment that changes the excitation current automatically according to a voltage change in order to stabilize the voltage automatically. AVR is applied to generators having a capacity of around 50 kw or more. The symol v 0 in Figure 28 is an AC voltage in the generator terminal that is built up when the excitation circuit is opened and the rotor is rotated at a rated revolution speed with no excitation current. The value of this voltage is important for automatically increasing the voltage in accordance with an increase in the revolution speed. It is usually in the range of 1-3% of the rated voltage. v 0 should be tested upon procurement and those having as high a value of v 0 as possible should be selected. (2) Single phase A.C synchronous generator (compound winding characteristics) -58- The Study on Introduction of Renewable Energies

66 Basically, a single phase generator has the same no-load saturation characteristics as a three-phase generator. The generator terminal voltage fluctuates along with a change in the revolution speed. The voltage will drop when loaded even if the revolution speed is kept constant. v 1 +v a (1) (2) i f C x Rotator Stator C 1 C 2 v 1 C 4 C 3 I V The compound generator reduces the voltage fluctuation resulting from the load fluctuation by the principle as illustrated in Figure 29. Magnetic flux created by the excitation coil C x of the rotor concurrently operates on the self-excitation coil C 1 and the generation coil C 2 of the stator and generates voltage in each coil. Figure 29 Compound Winding Single Phase Generator The stator has a coil C 3 that generates magnetic flux with the generator current and supplementary winding coil C 4 that generates induced voltage by of C 3. When load current flows, a total voltage of v 1 at C 1 coil and v a at C 4 coil operates on the excitation circuit and the excitation current increases. It then compensates for a drop caused by load current in the generator terminal voltage V. Load current A Generator voltage V Figure 30 illustrates the characteristics, which can be confirmed by a rise in the voltage v 1 + v a, to be measured between (1) and (2) in Figure 29, along with a load increase under constant speed operation of the generator. Figure 30 Load Characteristics of Compound Winding Single Phase Generator -59- The Study on Introduction of Renewable Energies

67 The revolution speed of this type of generator will be constant when the voltage is adjusted to be constant. It is suitable for transmission to an isolated electrification system and is recommended for use in Village Hydro. (3) Induction generator Induction motor generators could be also used as a generator by connecting a condenser to its terminals and rotating its shaft by engine or turbine to generate a voltage between the terminals as shown in U C C Figure 31. The capacity of the v condenser to be connected is obtained C from the following equation for the w current flowing when the motor is operated with no load. Figure 31 Condenser Excitation C = i we ω = 2 π f i : inflow current with no-load, A f: frequency, Hz E: voltage, V C: capacity of condenser, F Farad Voltage V Figure 32 shows an example of the characteristics of no-load voltage and current of three-phase squirrel cage induction motor of 2.5 kw. Electric Current A Figure 32 Example of No-load Voltage and Current -60- The Study on Introduction of Renewable Energies

68 When the motor is used as a generator at 230 V and 50 Hz, the capacity of the condenser to be connected between the terminals can be determined as follows: E = 230 V i = 3.5 A 3.5 C = = ( F) 50µ F 2π Residual voltage (V) Revolution speed (min-1) The voltage induction of the induction generator is also performed by residual voltage similar to the synchronous generator. Figure 33 shows an example of a 2.5 kw induction motor. Figure 33 Revolution Speed and Residual Voltage The residual voltage of the induction motor is small compared to a synchronous generator. The residual magnetism may be lost due to overloading during operation or a short-circuit. It is necessary to check the residual magnetism when voltage cannot be built up at starting. The characteristics of this generators are similar to a shunt winding generators, but are more difficult to control. It should be used where load fluctuation is as small as possible. Village Hydro for groups of some 20 households or so can be materialized by procuring a motor and condenser for a relatively low costs. 4.5 Power Transmission Mechanism The revolution speed of generators typically available for Village Hydro are mostly at 1,500 min -1, while turbines have various types and revolution speeds ranging from 70 min -1 to 1,120 min -1. Accordingly a gear system to increase the revolution speed is required to transmit the turbine output to a generator. (1) Speed Increaser This is the ideal power transmission mechanism, which is applied to a turbine-generator of more than 30 kw output. Series of gears are contained in -61- The Study on Introduction of Renewable Energies

69 an oil immersed casing for lubrication and cooling. A transmission efficiency of some 98% is obtained. A flange coupling is employed for connecting the turbine-speed increaser and speed increaser-generator. The centering between the turbine and generator is difficult since both employ roller bearings. Accordingly, a flexible coupling is used in order not to cause excess stresses on the bearing. (2) Belt transmission Belt transmission is most often applied for small capacity turbine-generator since it is easy to choose the necessary gear ratio. There are various types of belt such as plane belt, V-belt, and ditched belt. Among these, the V-belt is most commonly used. The pulley ratio to step-up the turbine speed by V-belt is up to 4:1 per step. A higher pulley ratio is obtained as follows: (D 2 and D 3 are fixed to the shaft ) D 1 D 2 D 4 D 3 N 1 N 2 D 1 N 2 = N1 D2 D D 3 4 Pulley ratio N = N Figure 34 Pulley Ratio by V-belt There are three types of V-belt; A, B, and C. Type A is the thinnest and is mostly applied to small output machines. When transmission power is large, multiple belts of Type A are used or a Type B belt is applied. Type A is applied in general. As the belt transmission is performed in a small space connecting turbine and generator, provision of a protective cover is required. In the case of a belt transmission for low speed turbine, a bending moment operates on the main shaft in addition to rotational torque. Accordingly, the 2 1 D1 D3 = D D The Study on Introduction of Renewable Energies

70 diameter of the shaft is designed larger than that of an ordinary shaft that receives only rotational torque. 4.6 Transmission Lines 230 V 600 V 600 V 230 V G V 1 V 2 Figure 35 Voltage Drop of Transmission Lines Step-up Transformer Table 15 The relationship between the size of the conductor and voltage drop is important for design and construction of transmission lines. The larger the conductor size, the smaller the voltage drop will be. However, a large conductor is costly and the supports poles and insulators will also be expensive. The generator voltage is often stepped up in order to facilitate the use of as small size conductors as possible. The relationship between conductor size and transmission distance is given by the equations in Table 15. Conductor Size and Transmission Distance Transformer terminal voltage for V 1 Volt transmission Voltage at receiving end V 2 Volt Tolerable ratio of voltage drop V= (V 1 -V 2 ) / V 1 x 2 = 15% Transmission power P W Power factor of load cos = 0.6 Transmission distance L m Size of ACSR a mm 2 Resistance constant of ACSR C = a r = 29.5 x 10-3 mm 2 /m Single phase L = 18 x 10-4 a V 2 1 / P 2 a = 557 PL / V 1 Three phases L = 62 x 10-4 a V 2 1 / P 2 a = 161 PL / V 1 L -63- The Study on Introduction of Renewable Energies

71 Tables 16 to 18 present the relationships of ACSR sizes and maximum transmission distances by voltage and phase. Table 16 ACSR Conductor Size and Max. Distance for Single Phase Transmission at 400 V and 230 V Village size Generator output Transmission distance at transmission voltage 400 V m, ( ) shows at 230 V Size of ACSR wire (mm 2 ) households kw (25) (40) (55) (80) (110) (140) (160) (28) (43) (60) (85) (120) (150) (170) (33) (53) (74) (105) (150) (190) (210) (38) (60) (83) (120) (167) (214) (240) (50) (80) (110) (160) (220) (285) (320) ,030 1,150 (60) (95) (130) (190) (270) (340) (380) ,000 1,290 1,440 (75) (120) (170) (240) (330) (430) (480) ,000 1,440 2,010 2,580 2,870 (150) (240) (330) (480) (670) (860) (950) ,150 1,800 2,500 3,600 5,000 6,460 7,180 (380) (600) (830) (1200) (1700) (2100) (2400) Table 17 ACSR Wire Size and Max. Distance for Single Phase Transmission at 600 V and 230 V Village Generator Transmission distance at transmission voltage 600 V m, ( ) shows at 230 V size output Size of ACSR wire (mm 2 ) households kw ,000 (25) (40) (55) (80) (110) (140) (160) ,060 1,180 (28) (43) (60) (85) (120) (150) (170) ,000 1,290 1,430 (33) (53) (74) (105) (150) (190) (210) ,130 1,450 1,600 (38) (60) (83) (120) (167) (214) (240) ,070 1,500 1,940 2,150 (50) (80) (110) (160) (220) (285) (320) ,290 1,800 2,300 2,580 (60) (95) (130) (190) (270) (340) (380) ,130 1,610 2,260 2,900 3,200 (75) (120) (170) (240) (330) (430) (480) ,000 1,620 2,260 3,230 4,500 5,800 6,460 (150) (240) (330) (480) (670) (860) (950) ,600 4,000 5,650 8,070 11,300 14,500 16,150 (380) (600) (830) (1200) (1700) (2100) (2400) -64- The Study on Introduction of Renewable Energies

72 Table 18 ACSR Wire Size and Max. Distance for Three Phase Transmission at 600 V and 230 V Village size Generator output Transmission distance at transmission voltage 600 V m, ( ) shows at 230 V Size of ACSR wire (mm 2 ) households kw ,300 1,900 2,600 3,350 3,700 (88) (130) (190) (280) (380) (490) (540) ,000 1,400 2,000 2,800 3,650 4,050 (95) (150) (200) (300) (410) (540) (600) ,250 1,700 2,500 3,500 4,450 5,000 (120) (180) (250) (370) (510) (650) (730) ,400 2,000 2,800 3,900 5,000 5,600 (130) (200) (300) (410) (570) (730) (820) ,200 1,800 2,600 3,700 5,200 6,700 7,450 (180) (280) (380) (540) (760) (980) (1100) ,400 2,200 3,100 4,500 6,250 8,050 8,900 (200) (320) (460) (660) (920) (1200) (1300) ,800 2,800 3,900 5,600 7,800 10,000 11,200 (260) (410) (570) (820) (1150) (1470) (1650) -65- The Study on Introduction of Renewable Energies

73 Pictures of Erecting Transmission and Distribution Lines Source: RDHG -66- The Study on Introduction of Renewable Energies

74 Source: RDHG -67- The Study on Introduction of Renewable Energies