Voltage and Frequency Controller for Parallel Operated Isolated Asynchronous Generators

This paper deals with a voltage and frequency controller for parallel operated isolated asynchronous generators used in constant power applications such as driven by uncontrolled pico hydro turbines. The proposed controller is having capability of controlling the voltage and frequency in decoupled manner. For controlling the voltage, a static compensator (STATCOM) is used as a reactive power compensator along with harmonic eliminator and a load balancer while for controlling the frequency; an electronic load controller (ELC) is used to regulate the total active power at the generators terminals. The STATCOM is realized using IGBTs (Insulated gate bipolar junction transistors) based voltage source converter (VSC), and a capacitor as an energy storage element at its DC link, while an ELC consists of a diode bridge rectifier, a chopper switch and an auxiliary load. The proposed generating system along with its controller is modeled in MATLAB using SIMULINK and PSB (Power System Block Sets) toolboxes. The simulated results are presented to demonstrate the capability of an isolated generating system with the proposed controller.