H-Bridge VSC with a T-Connected Transformer for a 3-Phase 4-Wire Voltage and Frequency Controller of an Isolated Asynchronous Generator

This paper deals with a novel solid state controller (NSSC) for an isolated asynchronous generator (TAG) feeding 3-phase 4-wire loads driven by constant power prime movers, such as uncontrolled pico hydro turbines. AC capacitor banks are used to meet the reactive power requirement of the asynchronous generator. The proposed NSSC is realized using a set of IGBTs (Insulated gate bipolar junction transistors) based current controlled 2-leg voltage source converters (CC-VSC) and a DC chopper at its DC bus, which keeps the generated voltage and frequency constant in spite of changes in consumer loads. The neutral point of the load is created using a T-configuration of the transformers. The TAG system is modeled in MATLAB along with Simulink and PSB (power system block set) toolboxes. The simulated results are presented to demonstrate the capability of the isolated generating system consisting of NSSC and TAG driven by uncontrolled pico hydro turbine and feeding 3-phase 4-wire loads.