Harmonic resonance repercussions of PV and associated distributed generators on distribution systems

Abstract

The problems associated with the harmonics needs more attention as more number of distributed generators like PV and wind are integrated into a distribution system. Although the integration presents a lot of benefits, satisfying the needs of local load requirements by reducing the line losses and facilitating congestion management, the problems of power quality that impact the distribution system become a priority. IEEE 519 describes network resonance as a major contributor impacting harmonic levels. LC and LCL filters on the AC side of PV Solar (PV) inverters that are designed to mitigate higher order harmonics tend to interact with the impedance of the entire network by exciting the harmonic resonance modes. Apart from that, wind based induction generators and induction motors are associated with terminal capacitors for voltage support. The interaction of such capacitive elements of distributed generators with the entire system impedance also impact resonance modes. To witness the impact of DG's, a control scheme for a 1.25 MW PV inverter based on hysteresis control with a simple LC filter is designed. This paper will serve as a reference for planning engineers and researchers working towards power quality by addressing the impacts of PV with distribution systems.