Study on Load Provided Short-Circuit Current to the Main Power Grid Based on the Electromagnetic Transient Simulation

Over-limit short-circuit current (SCC) has become a prominent risk endangering the main power grid in the load-center area. Currently the SCC provided by the load side motors is neglected in the main grid SCC calculations, which may bring non negligible errors to the SCC levels. In this paper, the influence of load and the distribution network on the SCC of the main power grid is studied by the electromagnetic transient simulation based on the PSCAD/EMTDC platform. A system model with four voltage levels, including a detailed distribution network structure, is set up. The loads are composed of a combination of motors, photovoltaic (PV) sources and impedance connecting to the distribution network with different electrical distance. Simulations show that the induction motors in the distribution system can inject large SCC to the fault point in the 500kV power grid. And the boosting impact of load on the SCC shows negative linear relationship to the average electrical distance of the distribution system.