An improved 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 is functioning as an improved electronic load controller (IELC) to regulate the frequency and as a source of reactive power to regulate the terminal voltage. Three single-phase voltage source converters (VSCs) are connected to each phase of the generator through three single-phase transformers and there is an auxiliary load with a chopper at the self-regulated DC bus of the IELC. These VSCs along with transformers provide their function as a voltage regulator, a harmonic eliminator, a load balancer and a neutral current compensator whereas the chopper and the auxiliary load at the DC bus are used to regulate the frequency. The complete system is modelled and simulated in MATLAB along with Simulink and 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/unbalanced loads.