Voltage and Frequency Control of Isolated Pico-Hydro System

Pico-hydro power plants are usually a stand-alone hydropower system built to provide electricity for rural communities and are adopted as major renewable energy because of their advantages over the large hydropower plants. However, they require a governing system to limit the variation of water turbine speed due to season change and variation of consumer load. These variations result in fluctuating output voltage and frequency from the generator. To solve this problem, constant voltage and frequency is achieved by controlling the electrical power output and water power input by means of electronic load controller, dump loads, power converters and mechanical regulation of turbine water flow. This paper reviews the different technologies of controlling voltage and frequency in Pico-hydro system. Furthermore, the use of a PV inverter in Pico-hydro and the maximum power point tracking technology to extract power from PV arrays will also be reviewed.