Advanced Universal Power Quality Conditioning Systems for Stabilizing Micro-Grid’s Frequency

This paper proposes a new unified active filter to alleviate instantaneous unwanted oscillating powers as they may lead to frequency variations in weak systems. First, the paper presents negative impacts of capacitive loads on the shunt active power filter performance in compensation of instantaneous oscillating real power. Secondly, an advanced universal power quality conditioning system (AUPQS) for three-phase/four-wire systems under non-ideal waveforms is introduced. By considering the suggested compensation algorithm, the AUPQS is able to extremely suppress instantaneous oscillating powers caused by distorted-unbalanced load-terminal voltages. Moreover, an independent single-phase converter is suggested at the load-end in order to regulate the DC-link voltage. Therefore, the instantaneous oscillating powers perfectly suppress and thus, the source-end three-phase currents will be purely sinusoidal. The suggested AUPQS is used to stabilize micro grid frequency. The effectiveness and flexibility of the proposed AUPQS are confirmed by Matlab/ Simulink simulations.