RF and Shunt Active Power Filters at Multiple Points of Common Couplings of Radial Electrical Systems

Abstract

This work investigates the effects of RL filters and single-phase Shunt Active Power Filters (SAPFs) on the supply and load current waveforms and their properties. The parameters involved are rms, input Power Factor (PF) and Total Harmonic Distortion (THD). These parameters can describe the quality of any electrical power system, especially PF and THD. This work focuses on implementing both filters in an electrical radial system due to the limited research work. Hence, the effects of utilising both filters in the radial system are studied. In this work, both filters connect at different Points of Common Couplings (PCCs) of a single-phase radial electrical system. The PCCs are located before composite loads (Case 1), before all nonlinear loads (Case 1) and before individual nonlinear loads (Case 3). Both Cases 1 and 2 apply a centralised SAPF, and Case 3 employs individual SAPFs. Matlab/ Simulink simulates all case studies under four operating conditions: (1) without any filters, (2) with SAPFs only, (3) with RL filters only, and (4) with the RL filters and SAPFs. According to the simulation results, the SAPFs require the RF filters to compensate harmonic components effectively. Otherwise, the SAPF’s injection current consists of high current spikes. However, the RF filters may slightly alter the load current waveforms, rms and THD values; the changes are insignificant. Moreover, based on the THD values of the compensated supply current waveform, the centralised SAPFs seem more suitable to be employed in the radial system. By utilising the centralised SAPFs, the THD values of the supply current are lower than using the individual SAPFs. Thus, it can be stated that the centralised SAPFs exhibit better performance. Nevertheless, connecting both filters on the PCCs of all nonlinear loads (Case 2) is suitable to avoid any linear load current waveform deterioration.