Fault characteristic analysis of photovoltaic inverter considering negative sequence control strategy

Abstract

In case of an asymmetrical fault in PV accessed system， the inverter will simultaneously control the outputs of positive and negative sequence currents. However， there are few studies on inverter fault characteristics considering negative sequence control strategy. Therefore， the solution method for the steady-state short-circuit current of the inverter is firstly derived. Then the short-circuit current characteristics and equivalent negative-sequence impedance characteristics of the inverter output under asymmetrical faults are investigated by considering different negative sequence control strategies. The similarity and difference in the fault characteristics of photovoltaic power generation under different control strategies and different fault types are demonstrated. Finally， a simulation model is built to verify the theoretical analysis results. The results show that the influence of negative sequence control strategy should be fully considered in the study of fault characteristics and protection principle with the integration of new energies.

Keywords

• photovoltaics
• inverter
• negative sequence control strategy
• short-circuit current
• equivalent negative sequence impedance