Decoupled electronic load controller for offgrid induction generators in small hydro power generation

Abstract

The control of voltage and frequency is one of the prime concerns in small off-grid hydroelectric power plants located in remote and inaccessible places. Induction generators are prime contenders for such applications which are robust, require less maintenance and have low cost. This paper deals with an implementation of a decoupled electronic load controller (DELC) for a three-phase induction generator (IG) system in standalone applications. The DELC is a combination of a static synchronous compensator (STATCOM) and conventional electronic load controller (ELC). The STATCOM consists of three-phase insulated gate bipolar transistor (IGBT) based current controlled voltage source converter (CC-VSC) with a dc bus capacitor and an ELC consists of an IGBT based chopper and an auxiliary load on the dc bus of the diode bridge rectifier. An Icos? based control algorithm is used in DELC to regulate terminal voltage and frequency, suppress harmonics and to provide load balancing. Test results are presented under balanced/unbalanced nonlinear loads to demonstrate the effectiveness of the DELC for an induction generator system.