Effectiveness of unified power quality conditioner for flicker mitigation

A linearised model of the power system with the electrical arc furnace (EAF) and the unified power quality conditioner (UPQC) has been developed in the frequency domain. It was found that the simulation of the EAF is possible even in the frequency domain by using a linearised model based on the Cassie-Mayr formula. The linearised model of the power system makes it possible to analyze basic properties of the system for perturbed signals and to find an optimum control strategy and parameters. The analysis indicates that the most effective may be such an application of the UPQC where the parallel active filter (AF) compensates the whole reactive power consumed by the EAF and delivers to the network a capacitive power to hold the voltage at the PCC constant, while the series AF compensates the fluctuating active power of the EAF.