Study on Finite Selectivity Based Regional Protection Suitable for Low-Voltage Microgrids

At present there is still no applicable selective protection for 400V microgrid,for this reason,based on actual parameters and operation characteristics of 400 V microgrid containing distributed generation(DG) a fault component based partitioned protection approach for microgrid is proposed.Dividing 400 V microgrid into several subareas and regarding each subarea as a unit to be protected,the high cost of configuring protection devices for primary equipments in the 400 V microgrid can be avoided and at the same time the infinite selectivity can be implemented.The negative-direction principle based on abruptly changed quantities caused by faults is applied to measuring elements,thus various unsymmetrical faults can be effectively identified.The additional auxiliary low-voltage startup criterion can get rid of adverse impacts of unbalanced load and switching of high-capacity single-phase load on the proposed protection.Results of simulation based on EMTDC show that the proposed protection approach is effective.