Forecast And Analysis Of Electromagnetic Interference In Substations

With the continuous increase of voltage grade in power system, study on its electromagnetic compatibility has become more and more important. Since there are too many electric equipment in the fixed space in substation, electromagnetic compatibility in substation is one of the research focuses in power system.In the air isolated substations, as one of the routine switch operations, isolator operation is the main source of the EMI in substations. When the isolator operates on the high voltage no-load bus, operation over-voltage and over-current will be resulted with high amplitude and speed along with the bus. Besides, high transient electromagnetic field will be generated in the space. Its transient electromagnetic wave can easily intrude into the control and protection equipment by space coupling and conduct coupling, brought about high EMI problems, thus they can't work properly.First, the electromagnetic transient state of isolator operation on no-load bus in a 500kV substation was studied on simulation and theory. The electromagnetic transient simulation model was created by EMTP-ATP on the network of the 500kV substation. The transient electromagnetic environment of isolator operation on no-load bus with and without branches in a 500kV substation was fully studied, and the transient over-voltage and over-current was analyzed. Compared with actual measurements, the simulation model has considerable accuracy, which proves that electromagnetic transient simulation was reliable and efficient, and it has high applicable value for study on EMI in substation.Second, gray forecasting theory was successfully introduced into the study on EMI in substations. On the study of the transient EMI of isolator operation in substation coupling conduction by CT and PT connected with bus, gray forecasting modeling theory with multi-variable was introduced, and the EMI gray forecasting model with multi-variable was created. This model has been improved on the backup value reconstruction and initial value selection, overcame the shortage of one model suitable for one data change rule.Case study reveals that the model has the merits of quick forecasting, few data, high accuracy, and it's feasible to use gray forecasting modeling theory with multi-variable to analyze the forecasting of EMI, which has more development and application prospect.