A kind of device used for simulating the process level fault of intelligent substation is designed to test the protection relay. Based on the “capture-modify-forward” method

the sampling value (SV) and generic object oriented substation event (GOOSE) in the process level network is transformed artificially. The information-entropy detection method is used to diagnose the voltage sags so that joint simulation between process level fault and power system fault can be realized. The fault simulator can easily access the process level network with the full duplex design. Out of consideration for both the operation time and hardware consumption

a multiply-accumulator with less pipeline levels is developed and multiplexing technology is used in information-entropy arithmetic. Tests show that the increased transmission delay by the fault simulator is less than 3 μs

which won’t have an effect on the process level network.