DEVELOPMENT OF ELC FOR MICRO HYDRO POWER STATION

Abstract

Micro hydropower plants are emerging as a major renewable energy resource today as they do not encounter the problems of population displacement and environmental problems associated with the large hydro power plants. They have been playing a great role to provide electricity to remote area especially in developing countries. However, they require control systems to limit the huge variation in input frequency expected in rivulets over which these are established to produce a constant power supply. So a controller is required to solve this problem, Electronic Load Controller (ELC) controls generator output voltage and frequency, irrespective of the amount of load connected to the generator in the micro-hydro systems. ELC does it by automatically dissipating any surplus power produced by the generator in additional load known as ballast load. Almost all of the micro hydro power systems are based on run-off-river type. The operating point of the generator is fixed such that it gives constant rated output at the rated conditions of voltage, current and speed, but the consumer load may vary. Now the variation in the consumer load connected is neutralised by the controller diverting the extra power to a dump load. In the case of peak load almost all the generated power is consumed but when the required load is less than the generated power, the voltage and the speed of the generator increases which causes serious problems in the system components. Over voltage may cause overheating, reduction in life of different devices whereas under voltage reduces the heat output in case of heating devices. To overcome such problems, Electronic Load Controller is used such that the generator is always at constant load all the time. The main objective of this dissertation is to present a literature review of available ELC technologies and to develop an ELC. for micro hydro power station. The designed ELC consists of a controlled bridge rectifier-chopper system feeding a resistive dump load whose power consumption is varied through the duty cycle of the chopper. This scheme can be efficiently used in micro hydro power stations.