Open-Delta VSC Based Voltage Controller in Isolated Power Systems

Abstract

This paper proposes a reduced switch voltage source converter (VSC) topology implemented as a voltage controller in isolated power systems. In isolated power systems generally self-excited induction generators (SEIG) are used mainly for their ruggedness and economic reasons. Mostly for constant power applications such as pico hydro uncontrolled turbine driven self excited induction generators feeding three-phase loads are employed. The proposed reduced switch voltage controller is used to regulate and control the voltage at the generator terminals as it is subjected to voltage drops, dips or flickers when the isolated power system is subjected to various critical loads. In this paper the controller is realized using a three-leg fourswitch insulated gate bipolar transistor (IGBT) based current controlled voltage-source converter (CC-VSC) and a self-supporting dc bus containing two split capacitors, thus reducing the IGBT count and hence cost. This reduced switch topology forms an Open-Delta type converter. The proposed generating system along with the controller is modeled and simulated in MATLAB along with Simulink and power system blockset (PSB) toolboxes. The system is simulated and the capability of the isolated generating system along with the reduced switch based voltage controller is presented here where the generator feeds linear and non-linear loads are investigated.