Battery Based Voltage and Frequency Controller for Parallel Operated Isolated Asynchronous Generators

This paper deals with a battery energy storage system (BESS) based voltage and frequency (VF) controller for parallel operated isolated asynchronous generators (IAGs) driven by uncontrolled pico hydro turbines used in constant power applications. The individual AC capacitor banks are used to generate the rated voltage at no load while additional demand of reactive power for the load and generators is met by the controller. The proposed controller is having capability of harmonic elimination, load balancing and load leveling along with voltage and frequency control. The proposed controller is realized using an IGBT (insulated gate bipolar transistor) based voltage source converter (VSC) and battery system at its DC link. Since the VSC allows bidirectional flow of active and reactive power; thus it regulates the voltage and frequency. The effectiveness of the proposed controller is demonstrated through the MATLAB based simulations using Simulink and PSB (power system block set) toolboxes and different aspects of the controller are studied for parallel operated isolated asynchronous generators.