Battery‐supported unified power quality controller for small hydro‐based isolated power generation

Abstract

In this paper, a battery-supported unified power quality controller (UPQC) for a small hydro-based isolated power generation is investigated as a voltage and frequency controller. The self-excited squirrel cage induction generator driven by constant power prime mover (small hydro turbine) has unacceptable voltage, frequency and power quality under non-linear loads. The battery-supported UPQC-based voltage controlled-voltage source converter is designed, modelled and simulated in MATLAB environment. Here UPQC has series and shunt converters with a battery and it is used to feed the local loads. This small distributed power generation system is capable to feed unbalanced non-linear loads because a shunt converter is used to take care the compensation of unbalanced loads and it always maintains the source currents balanced and sinusoidal. Moreover, a series converter is used to inject the series voltages in the self-excited squirrel cage induction generator terminals to regulate the common coupling point voltage during unbalanced non-linear loads. Performance of a battery-supported UPQC is also validated experimentally using a laboratory prototype of a 3.7 kW, 230 V, 50 Hz capacitor excited induction generator.