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

Abstract

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.

Keywords

• Asynchronous machines
• Voltage control
• Frequency control
• Control of electric power systems
• Distributed power generation
• Power supply quality and harmonics