A Fast Line Reclosing Strategy for Power System Under DG Access

For the automatic reclosing of power system under renewable energy source access, the current practice is usually to cut off the renewable energy source or block the reclosing gate after a fault occurs. This will lead to the shutdown of the renewable energy source and the interruption of power supply to a large number of local loads, which is not conducive to the safe operation of the grid and the efficient utilization of the renewable energy source. In this paper, a fast reclosing method is proposed for substation lines with inverter-type renewable energy source access, which can ensure the power supply of important loads and make the renewable energy source stable during the reclosing period without going off-grid. Firstly, it is pointed out that the inverter-type renewable energy source is switched to VSG-control during the reclosing period, so that it has the basic islanding operation capability. Then the method of load shedding with the startup of unloading resistor during the reclosing period is proposed to ensure the power balance between the new energy power and the loads. Next, adjusting the rated frequency of the renewable energy source to accelerate the simultaneous process, which can speed up the whole reclosing process. Finally, the simulations under different working conditions are carried out on the PSCAD/EMTDC to verify the feasibility of the proposed reclosing strategy.