In view of the actual situation that the present 500 kV grid is lack effective monitoring measures

in this paper

a kind of design method of overvoltage waveform data monitoring system based on the non-inductive capacitive unit to form into voltage divider which is embedded in the capacitor voltagetransformer is introduced. The monitoring system adopts ARM7 CPU processor to develop high speed wideband voltage monitoring device to record

store and transmit the waveform data of overvoltage. Andaccording to the actual conditions

the transient component extraction algorithm is developed for theengineering application

the transient component can be obtained by the original waveform subtracting thenumerical approximation fitting 50 Hz power voltage. The monitoring system has been put into long termlive operation at 500 k V Pingyao substation in East China Power Grid. The typical switch and lightningovervoltage waveforms recorded are analyzed by the use of transient component extraction algorithm. Theresults show both reliability and practicability of the monitoring system and analysis technology at site.