PI Controller Based Power Conditioning System for Superconducting Magnetic Energy Storage System

Abstract

A Superconducting Magnetic Energy Storage System (SMES) works on the principle of superconductivity, which is a phenomenon of occurring exactly zero resistance in certain materials when they are cooled below a certain temperature. The power conditioning system (PCS) of SMES consists of a bidirectional voltage source converter (VSC), a bidirectional chopper and a superconducting coil, which I designed mainly for the compensation of non-linear and pulsating loads. In this paper the PCS of SMES is designed to work both as a shunt active power filter and power conditioner at the same time. Two Hysteresis band controllers have been used to generate the pulses for the two bidirectional converters so as to attain the sinusoidal input source current at any load condition and to maintain the charge discharge cycle of SMES. DC link voltage is kept constant by DC/DC Bidirectional Converter and source current is controlled by Voltage Source Converter (VSC). At light loaded condition the superconducting coil will be in the charging mode and heavy loaded condition the superconducting coil discharges the stored energy in order to compensate the load changes, which is done with the help of a PI controller. The total harmonic distortion (THD) of the charging and discharging mode is well below 5% of the fundamental component. Simulation has been done in MATLAB/Simulink and results presented demonstrating the reliability of the power conditioning system.