Reliability Evaluation of Micro Hydro-Photo-Voltaic Hybrid Power Generation Using Municipal Waste Water

Transcription

1 R.K. Saket, R.. Bansal, an K.S. Anan Kumar / GMSARN International Journal (007) 3-0 Reliability Evaluation of Micro Hyro-Photo-Voltaic Hybri Power Generation Using Municipal Waste Water R.K. Saket *, R.. Bansal, an K.S. Anan Kumar Abstract This paper escribes a technology base on municipal waste water for electric power generation an evaluates the reliability of the micro-hyro-photo-voltaic (MHPV) hybri power system using Gaussian istribution approach an flow uration curve (FD). Reuse of municipal waste water of the city can be a stable, inflation proof, economical, reliable an renewable source of electricity. The hyro potential of waste water from community flowing through sewage system has been etermine to prouce a FD by orering the recore water flows. Several factors such as esign pressure, the roughness of the pipe s interior surface, metho of joining, weight, ease of installation, accessibility to the sewage system, esign life, maintenance, weather conitions, availability of material, relate cost an likelihoo of structural amage have been consiere for a particular penstock. A MHPV has been propose to provie reliable electric energy to Banaras Hinu University (BHU), Varanasi (Inia). Keywors Flow uration curve, micro-hyro-photo-voltaic hybri power system, municipal waste water, reliability evaluation.. INTRODUTION Small-hyro power (SHP) systems are relatively small power sources that are appropriate in many cases for iniviual users or groups of users who are inepenent of the electricity supply gri. Although this technology is not new, its wie application to small waterfalls an other potential sites is new. It is best suite to high falls with low volume, which occur in high valleys in the mountains. SHP is the application of hyroelectric power on a commercial scale serving a small community an are classifie by power an size of waterfall. A generating capacity up to 0 MW is generally accepte as the upper limit of small hyro, although this may be stretche upto 30 MW in some countries. Small hyro can be further subivie into mini hyro, usually efine as less than.0 MW, an micro-hyro which is less than 00 kw [], []. Hyroelectric power is the technology of generating electric power from the movement of water through rivers, streams, an ties. Water is fe via a channel to a turbine where it strikes the turbine blaes an causes the shaft to rotate to which generator is connecte which converts the motion of the shaft into electrical energy. Small hyro is often evelope using existing ams or through evelopment of new ams whose primary purpose is river an lake water-level control, or irrigation. A small-scale hyroelectric facility requires a sizeable flow of water * R.K. Saket (corresponing author) is with the Electrical Engineering Department, Institute of Technology, Banaras Hinu University, Varanasi (Inia). saketrk@yahoo.com. R.. Bansal is with the Electrical an Electronics Engineering Division, School of Engineering an Physics, The University of the South Pacific, Suva, Fiji, rcbansal@hotmail.com K.S. Anan Kumar is with the University Works Department, Banaras Hinu University, Varanasi (Inia), anan_kumarks@yahoo.com an a reasonable height of fall of water, calle the hea. Another avantage of using water resources is that hyraulic works can be mae simple an large constructions, such as ams, are not usually require []- [5]. When ams are necessary, they affect less area than in lower zones because of the steepness of the terrain. Dams, which exploit the kinetic energy of water by raising small quantities of water to heights through the use of regulate pressure valves, can provie water for omestic uses an for agriculture in areas that are moerately higher than ajacent water courses. Generally, in an autonomous hybri power system, the win/small-hyro power generators are the main constituents of the system an are esigne to operate in parallel with local iesel gris. The main reasons are to obtain economic benefit of no fuel consumption by win/hyro turbines, enhancement of power capacity to meet the increasing eman, to maintain the continuity of supply in the system, etc. Win/small-hyro system is highly fluctuating in nature [6]-[8] an may affect the quality of supply consierably an even may amage the system in the absence of proper control mechanism. Main parameters to be controlle are the system frequency an voltage, which etermine the stability an quality of the supply. In a power system, frequency eviations are mainly ue to real power mismatch between generation an eman, whereas voltage mismatch is the sole inicator of reactive power unbalance in the system [9], [0]. In a power system active power balance can be achieve by controlling the generation i.e. by controlling the fuel input to the iesel electric unit an this metho is calle automatic generation control (AG) or loa frequency control (LF). Another metho of controlling the frequency of hybri system is by means of controlling the output power which inclues ump loa control, priority loa control, battery energy storage (BES), flywheel storage, pump storage, hyraulic/pneumatic accumulators, superconucting magnetic energy storage 3

2 R.K. Saket, R.. Bansal, an K.S. Anan Kumar / GMSARN International Journal (007) 3-0 (SMES), etc. []. Reactive power balance in the hybri system can be obtaine by making use of variable reactive power evice e.g. static var compensator (SV) []-[5]. Micro-hyro power system using waste water from community neither requires a large am nor is lan flooe. Only waste water from ifferent parts of the city is collecte to generate power which has minimum environmental impact. After proper treatment water can be provie to farmers for irrigation purpose. Microhyro power using waste water of sewage plant can offer a stable, inflation-proof, reliable, economical an renewable source of electricity. This technology has been esigne an implemente at Institute of Technology, BHU, Varanasi (Inia). This paper presents a new renewable resource of hyroelectric power generation using waste water from community of the city.. SELETION OF BASI OMPONENTS OF SYSTEM The principal components of the micro-hyro power system using sewage system are shown in Fig.. Interconnection of the micro hyro an PV system for reliable operation of the hybri plant is shown in Fig.. A tailrace an solar pump through which the water is release back of the sewage storage plant to maintain hea of the water accoring to flow rate v/s uration curves is shown in Fig. 3. The basic components of typical hybri micro-hyro power plant using waste water from community are as follows: An intake or weir to ivert stream flow from ifferent parts of the city. A sewage line to carry water flow to the forebay from the intake of the system. A forebay tank an trash rack to filter ebris an prevent it from being rawn into the turbine at the penstock pipe intake. A penstock pipe to convey the waste water to the power source. ivil work components viz. hea work, intake, hearace canal/sewage lines, forebay/sewage reservoir tank, penstock pipe, power house an tailrace with back up system. Power house components (turbines, generators, rive system an controllers). A water turbine converts the hyro energy into mechanical energy that rives a generator (inuction, synchronous or permanent magnet A generator. which generates electrical power an an automatic control mechanism provies stable electrical power using municipal waste water of the city. Transmission an istribution network from generating plant to loa centre. (a) Selection of penstock pipe The penstock is often the most expensive item in the project which may cost upto 40% of total project cost. Several factors shoul be consiere when eciing which material to use for a particular penstock esign pressure i.e. the roughness of the pipe s interior surface, metho of joining, weight, ease of installation, accessibility to the site, esign life, maintenance, weather conitions, availability, relative cost an likelihoo of structural amage [3]. The pressure rating of the penstock is critical because the pipe wall must be thick enough to withstan the maximum water pressure otherwise there may be a risk of bursting. The pressure of the water in the penstock epens on the hea, the higher the hea, the higher the pressure. The most commonly use materials for a penstock are mil steel, high ensity poly ethylene (HDPE) an unplastifie polyvinyl chlorie (upv). The upv exhibits excellent performance over mil steel an HPDE in terms of least friction losses, weight, corrosion, an cost, etc. (b) Selection of turbines Turbine is connecte either irectly to the generator or via gears or belts an pulleys, epening on the spee require for the generator. The choice of turbine epens mainly on the hea an the esign flow for the propose micro-hyro power installation. The selection also epens on the esire running spee of the generator. To ajust for variations in stream flow, water flow to these turbines can be controlle by changing nozzle sizes or by using ajustable nozzles. Turbines use in the hyro system can be classifie as Impulse (Pelton, Turgo an ross flow), Reaction (Frencis, Propeller, an Kaplan) an Waterwheels (unershort, breastshot an overshot). Typical efficiency of Impulse an Reaction turbines range 80-95% an for Waterwheels it ranges 5-75% [3]. (c) Selection of generator Inuction an synchronous generators are use in power plants an both are available in three phase or single phase systems. Inuction generators are generally appropriate for micro hyro power generation []. Inuction generator offers many avantages over a conventional synchronous generator as a source of isolate power supply. Reuce unit cost, ruggeness, brush less (in squirrel cage construction), reuce size, absence of separate D source an ease of maintenance, self-protection against severe overloas an short circuits, are the main avantages [6]-[]. apacitors are use for excitation an are popular for smaller systems that generate less than 0 to 5 kw. All generators must be riven at a constant spee to generate steay power at the frequency of 50 Hz. The two pole generator with a spee of 3000 RPM is too high for practical use with micro hyro power system. The 500 RPM, four pole genitor commonly use. Generator operating at less than 000 RPM becomes costly an bulky an to match the spee of the generator to low spee of the turbine, a spee increasing mechanism such as belt an /or gear box is require. 4

3 R.K. Saket, R.. Bansal, an K.S. Anan Kumar / GMSARN International Journal (007) 3-0 Fig.. Principal components of micro-hyro power systems Fig.. Interconnection of the Micro Hyro an PV system for reliable operation of the hybri power system 5

4 R.K. Saket, R.. Bansal, an K.S. Anan Kumar / GMSARN International Journal (007) 3-0 Fig. 3. Solar pump for recycle waste water from the own stream to upstream storage reservoir 3. MEASUREMENT OF POTENTIAL POWER WITH VARIOUS HEAD AND WATER FLOW RATES The theoretical amount of power available from a microhyro power system is irectly relate to the flow rate (Q), hea (H) an the force of gravity (g) as given below, P th = Q H g () To calculate the actual power output (P act ) from microhyro power plant, it is require to consier friction losses in the penstock pipes an the efficiency of the turbine an generator. Typically overall efficiencies for electrical generating systems can vary from 50 to 70 % with higher overall efficiencies occurring in high hea systems. Therefore, to etermine a realistic power output as shown in Table, the theoretical power must be multiplie by an efficiency factor of 0.5 to 0.7 epening on the capacity an type of system as given below. Table. Typical power output with various hea an water flow rates P act = Q H g e () where e = efficiency factor (0.5 to 0.7). 4. FLOW DURATION URVE AND ENERGY ALULATION In the paper annual as well as monthly/aily flow uration curve (FD) has been obtaine for municipal waste water from community of the city by recoring water flows as shown in Fig. 4 (a). The loa uration curve (LD) of the hybri system has also been obtaine accoring to reliability evaluation of the plant as shown in Fig. 4 (b). The FD an LD are use to asses the expecte availability of water flow, loa variations an power capability to select the type of the turbine an generator. From Fig. 4 (a) it is seen that, there is a ifference in waste water flow between summer an winter an this can affect the power output prouce by a micro hyro power system. 7 Hea Flow rates (lps) (m) Power output (W) Flow Rate (GPS) Months of the year Fig. 4(a) Typical Annual Duration ureve of System 6

5 R.K. Saket, R.. Bansal, an K.S. Anan Kumar / GMSARN International Journal (007) 3-0 These variations have been consiere in the estimation of total energy generation expecte from the site with recycle of the water using solar pumping system as shown in Fig. 3. Peak eman as shown in Table has been calculate to evaluate the reliability []-[6] of the hybri power system. f ( P) P P 0.5 = e (3) π The aggregate generation capacity moel is approximate as Gaussian []-[3]. Loa (kw) c 0.5 c f() = e (4) π P s is known as probability of success an can be expresse as follows P s = e π c 0.5 c e P P 0.5 Equation (5) can be written as follows [4]. cp (5) Duration (hours) Fig. 4(b). Typical Loa Duration urve of the System Table. Sample loa analysis z ( ) 0.5 x + y Ps = e y x where β is given as follows. β = P + Equation (6) is simplifie as follows. (6) Appliances Fluorescent Lamps (4 No.) olour Television ( No.) Refrigera- -tor ( No.) Water pump ( No.) omputer ( No.) Power rating (W) Hours /ay Monthly consump tion (kwh) Annual consum ption (kwh) Total energy consumption RELIABILITY EVALUATION OF SYSTEM The loa on the MHPV hybri generating station accoring to loa uration curve of the sewage system to have a Gaussian istribution for a specifie time interval is given as follows. P s = = β + β e π e π 0.5 ( ) x 0.5( y x ) e y 0.5 ( y ) y = φ( β) Where, ϕ [β] is the area uner the normal istribution curve having 0 mean an stanar eviation [N (0, )] from - to β an this value can be conveniently obtaine from stanar normal istribution table. 6. RESULTS AND DISUSSIONS A MHPV hybri power system can be reliable an provie stable electric power. The reliability of MHPV hybri power system has been evaluate at ifferent conitions of the LD an FD using a methoology base on Gaussian istribution approach. The mean loa has been assume.0 kva. The mean capacity an stanar eviation ata are given in Table 3. The stanar eviations for both generating capacity an mean loa have been assume 0% of the generating capacity an mean loa respectively. Using the relation (7), the failure probability has been evaluate assuming (7) generating capacity =. kva as P F = Now the generating capacity is increase in step of 50 VA at the fixe value of the mean loa at.0 kva an 7

6 R.K. Saket, R.. Bansal, an K.S. Anan Kumar / GMSARN International Journal (007) 3-0 the probability of failure has been calculate. Various plots of failure probability v/s generating capacity are shown in Fig. 5, selecting the following values of the stanar eviations. Table 3. Mean capacity an stanar eviation kva kva kva kva kva = 0% = 0% =5% (a) [ =0% of L an (b) [ =0% of L an (c) [ =0% of L an () [ =0% of L an =0% of ] = =0% of ] = =0% of ] = 3 =0% of ] = 4 The various curves are rawn for various combinations of an as shown in the Fig. 5. It is observe from curve A an B that for the same generating capacity of the system, the probability of failure with is more than. This is ue to fact that large uncertainty involve in generating capacity istribution function. Failure probability A B Generating capacity (VA) Fig. 5. Failure probability v/s generating capacity of power system Similarly by observing the curve A an for the same generating capacity the probability of failure for is more than 3 an so on. From the curve D, the failure probability for any generating capacity is more than from other curves. In summary, the probability of failure increases with either increase of or increase of c or D both an c. 7. ONLUSIONS A MHPV hybri power system is stable, cheap an capable of proucing reliable power because the hea/pressure of the sewage reservoir has been maintaine at constant using back up service by PV pump in summer an winter cycles of the country. A new methoology has been introuce in this paper for hybri generating system reliability evaluation using ifferent loa an generation moels. The evaluation of loss of loa probability has been base on loa generation moels as peak loa of the MHPV hybri power plant is less than generating capacity, failure probability is negligible; an normal istribution is assume as generation capacity moel an loa uration curve as loa moels an normal istribution moel as generating capacity. Further in all cases it is confirme that the failure probability of the system increases with an increase in variance of loa or generation capacity. AKNOWLEDGMENT Authors are grateful to BHU, Varanasi (Inia) for the encouragement an financial support for carrying out the research work. NOMENLATURE P = Deman at the generating stations P = Average or mean loa of plant = Stanar eviation of eman = apacity of the generating station = Mean capacity of the plant c = Stanar eviation of capacity P F = Probability of failure of generating station P S = Probability of success of generating station P th = Theoretical power output in kw Q = Usable flow rate in m 3 /s H = Gross hea in m g = Gravitational constant (9.8m/s ) LOLP = Loss of loa probability f (L) = Normal istribution L = Total loa in VA Φ = Rotational angle Φ(β) = Area uner normal istribution curve S = Safety factor n = Total uration of the stuy P fi = Failure probability for L i th loa level 8

7 R.K. Saket, R.. Bansal, an K.S. Anan Kumar / GMSARN International Journal (007) 3-0 REFERENES [] Bhatti, T.S.; Bansal, R..; an Kothari D.P. (E.) Small Hyro Power Systems. Delhi, Inia: Dhanpat Rai an Sons. [] Jianong, T.; Naibo, Z.; Xianhuan, W.; Jing, H.; an Huishen D. (E.) Mini Hyropower. hichester, Englan: John Wiley an Sons. [3] Fraenkel, P.; Paish, O.; Harvey, A.; Brown, A.; Ewars, R.; an Bokalers, V. 99. Micro-Hyro Power: A guie for Development Workers. Lonon, UK: Intermeiate Technology. [4] Tripathy, S.. an Bharwaj, V Automatic Generation control of a small hyro-turbine riven generator. Energy onversion an Management, 37(): [5] Roy, S Optimal planning of generating units over micro-hyro resources within a catchment area. IEEE Trans. Energy onversion 0(): [6] Bhatti, T.S.; Bansal, R..; an Kothari D.P. 00. On some of the esign aspects of win energy conversion systems. Energy onversion an Management 43(6): [7] Bansal, R..; Zobaa, A.; an Saket, R.K Some issues relate to power generation using win energy conversion systems: an overview. Int. Journal of Emerging Electric Power systems 3(): -9. [8] Bhatti, T.S.; Bansal, R..; an Kothari D.P., 00. Some aspects of gri connecte win electric energy conversion systems. Interisciplinary Journal of Institution of Engineers (Inia) 8(): 5-8. [9] Bhatti, T.S.; Al-Aemi, A. A. F.; an Bansal, N. K Loa frequency control of isolate win iesel hybri power systems. Energy onversion an Management 38(9): [0] Bhatti, T.S.; Al-Aemi, A. A. F.; an Bansal, N. K Loa-frequency control of isolate winiesel-micro hyro hybri power systems (WDMHPS). Energy (5): [] Hunter, R. an Elliot, G Win-iesel systems: a guie to the technology an its implementation. New York, USA: ambrige University Press.Bansal. [] R Automatic reactive power control of isolate win-iesel hybri power systems. IEEE Trans. of Inustrial Electronics 53(4): 6-6. [3] Bansal, R Reactive power compensation of win-iesel hybri power systems using matlab/simulink. Int. Journal of Energy Technology an Policy 3(3): [4] Bhatti, T.S.; Bansal, R..; Kothari D.P.; an Bhat, S Reactive power control of isolate winiesel-micro-hyro hybri power systems using matlab/simulink. Int. Journal of Global Energy Issues 4(/), [5] Bhatti, T.S.; Bansal, R..; an Kothari D.P Automatic reactive power control of isolate winiesel hybri power systems for variable win spee/slip. Int. Journal of Electric Power omponents an Systems 3(9): [6] Bhatti, T.S.; Bansal, R..; an Kothari, D.P A bibliographical survey on inuction generators for application of non-conventional energy systems. IEEE Trans. Energy onversion 8(3): [7] Nacfaire, H. (Eitor) Win-iesel an win autonomous energy systems. Lonon, UK: Elsevier Applie Science. [8] Twiel, J.W. an Weir, A.D Renewable Energy Sources, n Eition, New York, USA: Taylor an Francis. [9] Sanhu Khan, P.K. an hatterjee, J.K Three-phase inuction generators: a iscussion on performance. Electric Machines an Power Systems 7(8): [0] Bansal, R Three-phase self-excite inuction generators (SEIG): an overview. IEEE Trans. Energy onversion 0(): [] Simoes, M.G. an Farret, F.A Renewable Energy Systems: Design an Analysis with Inuction Generators. New York, USA: R Press. [] Arya, L.D.; hoube, S..; an Saket, R.K omposite system Reliability Evaluation base on voltage stability limit. Journal of The Institution of Engineers (Inia) EL-80(): [3] Arya, L.D.; hoube, S..; an Saket, R.K. 00. Generation system aequacy evaluation using probability theory. Journal of The Institution of Engineers (Inia) EL-8(): [4] Saket, R.K. an Bansal, R Generating capacity reliability evaluation using gaussian istribution approach, Proc. of the Int. onf. on Reliability an Safety Engineering, Kharagpur, Inia. -3 December. Reliability Engineering entre, Inian Institute of Technology. [5] Saket, R.K. an Bansal, R Reliability evaluation of interconnecte composite electrical power system consiering voltage stability at continuation power flow, Proc. of the Int. onf. on Power System Operation in Deregulate Regime (IPSODR-006), New Delhi, Inia. 6-7 March. Institute of Technology, Banaras Hinu University, Varanasi Allie publishers Pvt. Lt. [6] Saket, R.K. an Kaushik, S.P Use of gaussian istribution metho for biorhythmic analysis to prevent aviation accient, Pro. of the 4 th ISME Int. onf. on Mechanical Engineering in Knowlege age, Delhi, Inia. December. Delhi ollage of Engineering. 9

8 0 R.K. Saket, R.. Bansal, an K.S. Anan Kumar / GMSARN International Journal (007) 3-0