A frequency based electronic load controller for an isolated asynchronous generator feeding 3-phase 4-wire loads

Abstract

This paper deals with a voltage and frequency control of an isolated asynchronous generator feeding 3-phase 4-wire loads in constant power applications where terminal voltage, excitation capacitor, speed and generated power of the generator remain constant under all operating conditions. The proposed controller functions as an improved electronic load controller (IELC) to regulate the frequency and control the reactive power to regulate the terminal voltage. The proposed controller consists of 4 -leg IGBT (Insulated Gate Bipolar Junction Transistor) based VSC (Voltage Source Converter) which is connected to the each phase of the generator through interfacing inductors and there is an auxiliary load with a chopper at the self regulated DC bus of IELC. The controller provides the function of a voltage regulator, a harmonic eliminator, a load balancer and a neutral current compensator while the chopper and auxiliary load at the DC bus are used to regulate its voltage. The complete system is modeled and simulated in MATLAB along with Simulink and PSB (Power system Block set) toolboxes. The simulated results are presented to demonstrate the capability of an isolated generating system driven by uncontrolled pico hydro turbine and feeding 3-phase 4-wire linear/non-linear balanced/un-balanced loads.