http : //www.cigre.org C4-1059 AORC Technical meeting 2014 Case Study of Micro Power Grid Applications in Remote Rural Area of Thailand SUMMARY Payon Punjad, Pongsakorn Yuthagovit, Saranyphong Atchvsunthon Provincial Electricity Authority (PEA) Thailand Over the past decades the awareness of energy shortages and environmental concerns is the key issue causing many countries has set targets for clean, secure and adequate supply of energy for the future. Thailand is one of many countries under Kyoto Protocol has set policy on the sustainable and environmentally friendly development in energy sector by promoting Renewable Energy (RE) and Distributed Generation (DG) in power industry. Provincial Electricity Authority (PEA) is a state owned enterprise taking responsibility to provide electricity and services to customers for the whole country except metropolitan area. PEA has been supplying power to customers in the vast and different geographical areas covering large cities, small towns, urban and rural areas. For example, Maesariang district is a small remote rural town located in the north-west border of Thailand where there is no power substation, the sources of energy are small local power plants such as diesel generators, photovoltaic and micro hydro power plants but the main energy source is a power distribution line from Hod power substation. This power line is 110 kilometres long runs through mountain ranges and national reserved forests resulting in low reliability of power system. In order to improve power system reliability and services to customers, PEA has established the Maesariang Smart Micro Grid Project under the PEA s 11 th power system development plan in accordance with the National Economic and Social Development Plan. The feasibility study on Micro Grid development project is conducted, the study results will be guidance for the implementation phase. This paper presents the concept of the solutions to the power system problems of Maesariang district by integrating various kinds of energy sources in the area with the smart grid technology to deal with low reliable power system and lack of security of supply. Then power system study and simulation results are presented, followed by feasibility study of the project e.g. financial and economic analyses. payon.pun@pea.co.th
1. Introduction The evolution of power markets worldwide has been driving power industry to improve their investment, planning and operation. This has caused Distribution Network Operators (DNOs) to identify and develop more economical methods of supplying energy to deal with increased energy demand and uncertainty of energy sources in the future. Maesariang district is one of the area where power outage frequently occurred, and is the highest power outage of Thailand. In order to deal with this serious power system problem, PEA, Chiangmai University and Smartergrid Solutions Co., Ltd (a spin out company from University of Strathclyde, UK) has conducted the feasibility on micro power grid development project. 2. Power System of Maesariang District The existing power system of Maesariang district, Maehongson Province can be described by Figure 1. Figure 1: Single Line Diagram of Power System The energy usage of customers of Maesariang district is supplied by Hod power substation via 22 kv power distribution line (Feeder No.9, F9) equipped with two of Automatic Voltage Regulators. 2
In case of F9 could not supply power to Maesariang, the energy will be supplied via feeder No.6 of Chomthong substation which is located 170 kilometres away from Maesariang. The system reliability (SAIFI and SAIDI) of Maesariang district are as follows: Description 2010 2011 2012 2013 With Micro Grid Project SAIFI (Outages) 26.5 26.1 17.6 22.3 4.75 SAIDI (Min.) 2,029 1,396 1,650 1,188 68.11 Table 1: Reliability of Power System of Maesariang District 3. Power System Study The existing power distribution from Hod power substation which is the main source of energy comprises of 25 MVA power transformer, two of AVRs, two sets of capacitor bank and demand 3 MVA at 0.9 pf. Figure 2: Power Distribution Line from Hod to Maesariang 1.06 DIgSILENT [p.u.] 1.04 1.02 1.00 0.98 0.96 0.00 50.00 100.00 150.00 200.00 [km] 250.00 HOA09N1389 HOA09N399n HOA09N428 HOA09N427 HOA09N397 HOA09N150 HOA09N552 HOA09N1134 HOA09N385 HOA09N513 HOA09N146 HOA09N867 HOA09N1294 HOA09N144 HOA09N130 HOA09N929 HOA09N837 HOA09N947 HOA09N304 HOA09N940n HOA09N541 HOA09N1331 HOA09N212 HOA09N123 HOA09N7 HOA09N923 HOA09N1298 HOA09N222 HOA09N1205 HOA09N710 HOA09N534 HOA09N638 HOA09N27 HOA09N310 HOA09N498 HOA09N842 HOA09N700 HOA09N471 HOA09N293 HOA09N674 Voltage, Magnitude Voltage Profile-HOA09 Date: 8/1/2013 Annex: /3 Figure 3: Voltage Profile of Power Distribution Line (Feeder No.9) 3
Figure 3 presents result showing voltage profile along feeder No.9 at normal demand period of project area. As can be seen in Figure 3, voltage level of the feeder before adding AVRs tend towards below 1.0 pu and even below statutory limit. The AVRs lift up the voltage level close to 1 pu; however, when the demand is increasing to the peak period (9 MW) or decreasing down to normal period, the AVRs could not maintain the voltage level. This has caused local DGs could not connect to the power grid, this voltage problem will be solved by transforming power grid to Micro Power Grid. 4. Development of Power System HOA08 HOA09 AVR1 AVR1 NCC North 1 AVR2 AVR2 Hydro SW6 LC Micro Grid Controller (MGC) Mae Sariang Substation SW5 SW1 SW2 SW3 Deisel Engine BATTERY Solar Farm F1 F5 F2 F3 F4 LC LC LC SW4 Measurement Point and Protection LC Local control Figure 4 : Micro Power Grid Configuration Figure 4 : According to the existing power grid and the problems occurred in this project area, the number of possible Micro Grid Systems have been investigated and studied in order to match the requirements of energy usages, geographical area, system configurations and other factors. The possible Micro Grid System for Maesariang District is described by Figure 4 that the major components and functions are the following: Micro Grid Controller commands and processes data from generators and all switching equipment. 4
The inverters of solar farm manage active power and reactive power supplied to the grid. Battery storage, diesel engine and hydro power plants supply power to the grid during power outage. Telecommunication is also the key component of Micro Grid system which support micro grid controller and system components. Power protection system works for two modes: grid connected and islanding modes. 5. Feasibility Study of the Project This section presents the feasibility study on micro power grid development project which is the important part of the project development. The financial and economic studies were conducted to find the most possible outcomes, the study results of both financial and economic will be the financial plan for the project implementation. Scenarios Power (MW) Time(Hrs.) Energy (MWh) Diesel Generators (MW) MBaht FIRR (%) EIRR (%) 1 3.0 306.00 1.52 10.28 0.5 1.5 2 6.0 333.00 N/A 8.33 3 3.0 380.00 N/A 5.12 3 MW 1.0 3.0 4 6.0 407.00 N/A 3.31 5 3.0 529.00 N/A N/A 2.0 6.0 6 6.0 556.00 N/A N/A 7 3.0 449.00 8.69 11.98 0.5 3.0 8 6.0 476.00 7.79 11.04 9 3.0 598.00 3.25 7.14 6 MW 1.0 6.0 10 6.0 625.00 2.29 6.37 11 3.0 875.00 N/A -1.61 2.0 12.0 12 6.0 902.00 N/A -6.97 Table 2: Financial and Economic Analyses As revealed by table 2, the number of different financial and economic results present that the lowest investment cost (scenario No.1), 3 MW of battery and 3 MW of diesel generator yield 10.28% economic. In addition, scenario No.7 is the most interesting financial and economic returns but need more investment in battery storage to supply more energy demand. However, the system planners have to choose not only the scenario that suits the budget and also the available and mature technology in the markets. 6. Conclusions This paper presents the simulation results of power system study of micro grid development and financial and economic analyses. The reliability of power system have been improved by 5
developing the existing power grid to micro grid equipped with micro grid controller, telecommunication equipment, switching devices and other component. The feasibility study on micro grid development is also presented, the selection of the most suitable financial and economic results must also consider investment plan and other important factors such as micro grid technology, planning and operation as well as maintenance. 7. References 1. Feasibility Study on Micro Grid Development Project of Maesariang District. PEA, Thailand, 2014 2. DTI/OFGEM, Embedded Generation Working Group, December 2000, Future Network Design, Management and Business Environment, UK 3. DTI, New and Renewable Energy Programme, (Contractor: EA Technology) Solutions for the Connection and Operation of Distributed Generation, Contract Number: K/EL/00303/00/01/REP, URN/03, July 2003, UK 4. Jenkins, N., Allan, R., Crossley, P., Kirschen, D., and Strbac, G. (2000) Embedded Generation, The Institution of Electrical Engineers, UK 5. Ault, G.W., Elders, I., Galloway, S., McDonald, J. R., Kohler, J., Leach, M. and Lampaditou, E. (2005) Electricity Network Scenarios for 2050, SuperGen Future Network Technlogies Consortium, UK 6