This parallel/grid connected system consists of medium voltage (6.3 or 10.5KV) generator sets, medium voltage parallel switch cabinets (withdrawable), PT (voltage transformer) cabinets, outgoing cabinets, parallel/grid connected control devices, etc. There are also generator set star point grounding resistor cabinets and differential protection devices for backup. The entire system is combined together to supply power to the grid or directly to the load. The key equipment of the system is switches and comprehensive protectors; The key points are parameter programming, setting, and device debugging.