CONTROL OF SELF-EXCITED INDUCTION GENERATOR FOR BALANCED AND UNBALANCED CONDITIONS

Abstract

Use of self-excited induction generator is being considered for the harnessing the renewable energy resources such as small hydro and wind. Self excited induction generator has so many advantages like robust construction, cheaper, simple construction, self protection against short-circuit etc so because of these qualities it is found to be most suitable for remote areas and so Induction machine operating as generator have been utilizing in remote location in mini/micro hydro power plants. As machine required reactive power for its operation so a capacitor bank is needed for it's voltage build-up process and to maintain rated voltage machine should suppose to work in saturation region. It is important to find out the value of capacitance required for self excitation process at different load condition. An iterative method is used to find the value of capacitance and a program has been written on MATLAB to obtain the value of frequency and capacitance required. Self excited induction generator is operated in balanced and unbalanced condition with different types of loads like three phase resistive load, resistive—inductive load and dynamic load like three phase induction motor, single phase and three phase unbalanced load simultaneously and with rectifier type of load also. Here total harmonic distortion (THD) and negative sequence current are also calculated to analyze the generator performance. Since it is operating under various kinds of rough atmospheric conditions the effects of various types of faults on whole system has been observed. Its requirement of reactive power is fulfilled only with the help of capacitor bank, but with variable load condition it is very difficult to maintain rated value of supply voltage since demand and supply of reactive power variable so reactive power compensation with the help of capacitor switching and with the Electronic Load Controller (ELC) is used and performance of generator is analyzed. A comparison is done between the performance of above given control techniques. Here the discussed electrical system is modeled and simulated in MATLAB/SIMULINK environment.