A Study on the Impact of the Large-scale Distributed Photovoltaic Power on the Distribution Grid System Protection

Access to a large proportion of distributed photovoltaic power will change the structure of distribution network and the distribution of fault current, which shall make the original relaying protection program not adaptive any more. Therefore research on the influence of a large amount of distributed photovoltaic power access on the main transformer of distribution network and distribution line is of great importance to the network security operation. Based on the PSCAD/EMTDC software, the present author establishes an 110kv substation and a 10kv radiating structure feeder circuit simulation models which are in accordance with a certain region's actual power system. Based on this, the author then makes a detailed and simulated analysis about the influence of a larger amount of PV power access to the medium and low voltage distribution on the reliability and sensitivity of main transformer zero-sequence voltage protection, zero-sequence current protection and distributed power circuit current protection.