DESIGN OF AN IMPROVED ELECTRONIC LOAD CONTROLLER

Abstract

Power is the important backbone of a nation in the developing world. It is realized that renewable energy plays most important role as add on to the available electrical energy. Among all renewable energy available, MHPP is one of the promising sources. Renewable energy plays a significant role to fulfil the economic development of the isolated / rural areas which include many other sources like solar energy, tidal, wind, geothermal, biomass energy and the flowing water stream which can be easily accessible in isolated / remote areas like are villages, ships, island, hilly areas, military etc. among the above mentioned sources hydro power is the most reliable source. Micro hydro is one type of hydroelectric which produces power up to 100kW by use of the flowing water stream. Advancement of Micro Hydropower Plant (MHP) helps to electrify the rural areas where the grid power is inaccessible. Usually self-excited synchronous or asynchronous generators are employed in micro hydro power plants. As these generators are engaged with continuously varying load, it may be unendurable to voltage and frequency fluctuations. To mitigate this fluctuation, the generator is employed with Electronic load controller (ELC). Typically, the rating of the dump load in ELC will be equivalent to the generator rating for maintaining the generator output constant at all the time. Operating the generator with full load provides less efficiency and reduction in lifespan. In this, aforementioned limitation has been knocked out by proposing a reduced dump load strategy on the existing electronic load controller. Also the thermal stress of the synchronous generator with the proposed strategy is experimentally investigated and compared with the existing method. In addition the switching behavior of synchronous generator in the course of main load and dump load under various load points are discussed. So the aim of this thesis is to reduce the power losses and to enhance the life span of the hydropower generator by lessening the electro thermo-mechanical stresses using reduced dump load strategy. Due to sensor fault, the ELC may cause to the generator to overload or over voltage which may lead to more damage to the generator or to the connected load so that the load controller has attempted to take into consideration the limitations of sensor faults, identif'ing sensor fault and its control by using various rules and learning based approach.