VSC with Zig-Zag Transformer Based Decoupled Controller for a Pico Hydro Power Generation

This paper deals with the decoupled voltage and frequency controller (DVFC) for isolated asynchronous generator (IAG) used in pico hydro power generation for feeding 3-phase, 4-wire loads. The proposed controller is used to control the voltage and frequency through control of active power at the generator terminal independently. The decoupled controller is a combination of a static compensator (STATCOM) consisting VSC with zig-zag transformer for regulating the voltage and an electronic load controller (ELC) for controlling the active power which in turn controls the system frequency constant. The STATCOM is realized using IGBT (Insulated Gate Bipolar Junction Transistor) based current controlled voltage source converter (CC-VSC) and a self supporting DC bus, while ELC consists of 3-phase diode rectifier, chopper switch and auxilliary load. The proposed generating system is modeled and simulated in MATLAB along-with Simulink and PSB (Power System Blockset) toolboxes. The simulated results are presented to demonstrate the capability of generating system for feeding 3-phase 4-wire loads.