Instantaneous Symmetrical Component Theory Based Voltage and Frequency Controller for Isolated Small Hydropower Generation

Abstract

This article deals with the design and implementation of an instantaneous sequence component theory based integrated voltage and frequency controller for an isolated asynchronous generator, which is used in constant power small hydropower generation for feeding three-phase four-wire consumer loads. The proposed integrated voltage and frequency controller is used to control the voltage and frequency of an isolated asynchronous generator in the integrated manner. This integrated voltage and frequency controller is realized using a zigzag/star transformer and a three-leg insulated-gate bipolar transistor based current-controlled voltage source converter, a capacitor, a chopper switch, and an auxiliary load on its DC bus. The proposed integrated voltage and frequency controller with an isolated generating system is modeled and simulated in MATLAB along with Simulink and simpower system (SPS) toolboxes (The MathWorks, Natick, Massachusetts, USA). The simulated results are validated with test results of a developed prototype using a 3.7-kW, 230-V asynchronous generator to demonstrate its performance for feeding three-phase four-wire consumer loads with the neutral current compensation.