Direction Criterion for Phase-to-phase Short-circuit Faults in Distribution Networks with Photovoltaic Based on Negative-sequence Current Amplitude

When faults occur in the distribution network with the integration of distributed photovoltaic, the performance of traditional power direction element decreases under the influence of photovoltaic low voltage ride-through and negative-sequence current suppression control strategies. Firstly, this paper analyzes the distribution characteristics of negative-sequence current and negative-sequence voltage when a phase-to-phase short-circuit fault occurs in the forward and backward areas of protection in a typical two-feeder distribution network. On this basis, a method for identifying the direction of phase-to-phase short-circuit faults in distribution networks with the access of distributed photovoltaic is proposed. The reliable identification of the direction of phase-to-phase short-circuit faults is achieved by using the amplitude of negative-sequence current, and the negative-sequence voltage criterion is introduced to achieve reliable blocking under three-phase short-circuit faults. Furthermore, a theoretical calculation method for the action setting values of the criterion is proposed, and the influence of photovoltaic integration capacity on the sensitivity of the proposed directional criterion and its maximum transition resistance tolerance are quantitatively analyzed. Finally, case simulations are conducted based on the PSCAD/EMTDC platform, and the results verify the effectiveness of the proposed criteria. © 2024 Automation of Electric Power Systems Press. All rights reserved.