Control Topologies for 3-Phase SEIG used in Small Hydro Power Plant Feeding Isolated Domestic Load in Remote Mountainous Region

Objectives: This paper is to highlight the various control topologies used in 3-phase Self-Excited Induction Generator (SEIG) used in pico-hydro power generation system feeding isolated load. Methods/Statistical Analysis: The various topologies of these controllers which are also known as Electronic Load Controllers (ELC) include conventional as well as STATCOM based controllers using various power electronics devices for power system parameters regulations and power quality control. The Self-excited induction generators are most suitable for pico and micro hydro power generation systems feeding isolated load due to their advantages over conventional synchronous generators. Findings: In isolated mode of operation of self-excited induction generators, a suitable control is necessary to maintain the voltage & frequency of the generated output within permissible limits under varying loading conditions. This is achieved by using an Electronic Load Controller (ELC) and dump load in the system. The main aim of the control strategy is to control the voltage output of SEIG and to maintain the desired frequency of the generated output. These electronic load controllers regulate the dump load in the system so that total load seen by SEIG remains constant under varying consumer load conditions and thus maintaining the frequency of the system. From the analysis of various types of these controllers, it is found that simplest of the electronic load controller is conventional diode rectifier based ELC. However, it suffers with the problems of harmonics in the circuit. Modern ELCs use voltage source converters along with different transformer configurations for better power quality control and better voltage and frequency regulations under different operating conditions. Improvements: Fast computational capabilities of DSP are also used to control the STATCOM switches and chopper circuit in ELC for better and fast control. The use of different transformer configurations such as star-delta and zigzag type provide neutral path for 3-phase, 4-wire system apart from eliminating the 3rd harmonics in the system.