Role of DC-MLI based D-STATCOM in distribution network with FOC induction motor drive

Abstract

The main objective of Power System engineers is to meet the consumers demand. Rated voltage and rated frequency supply should be supplied to the consumer end. With the introduction of many non-linear loads at the consumer end, Power Quality problem is a serious threat to the Power System. Power Quality problem is any occurrence in voltage, current or frequency deviation that may result in failure or mis-operation of electrical appliances. Common Power Quality problems that can be observed in daily life are voltage sag, voltage swell, voltage flickering, over-voltage and under-voltage. Impulsive transients, oscillatory transients and harmonics are also some of the Power Quality problems. The potency of D-STATCOM using SRF control theory in a Distribution Network with Field Oriented Control (FOC) Induction Motor drive as non-linear load with Diode-Clamped Multilevel inverter is examined. The FOC induction motor drive is a non-linear load which introduces harmonics into the distribution network when operated. D-STATCOM is a shunt linked device used for the reactive power compensation, for harmonic elimination and load balancing. D-STATCOM is a Custom Power device used at the distribution end to counteract the Power Quality problem. The conceptualization of Multilevel inverters came around 1975. For high-power and medium-power applications, Multilevel inverters are used as they can extract input current and produce output voltage with very low distortion. They even reduce the dv/dt stress and can operate at both fundamental switching frequency and high switching frequency. All these benefits cannot be retained through conventional VSI and CSI. These can generate output voltages with mature medium-power semi conductor technology with lower distortion. As the number of levels increases, the output waveform approaches more towards sinusoidal wave with a reduced harmonic distortion. Simulation of D-STATCOM using SRF control theory with 7 level Diode-Clamped Multilevel Inverter has been performed in MATLAB/SIMULINK.