Characteristics Of Disturbances At The Intelligent Component In GIS

Very fast transients are generated during the disconnector(DS)or circuit breaker(CB)operations in GIS(Gas-Insulated Switchgear,GIS)subsations.VFTO(Very Fast Transient overvoltage,VFTO)leaks out of the GIS at the discontinueties and excites the the electromagnetic disturbance,which may cause mulfuntions in the secondary equipment in GIS or even damage them.The intelligent component,as the core device of secondary equipment,is especially vulnerable to the electromagnetic disturbance.Sometimes,the intelligent component will be hazarded when the port disturbance voltage exceeds the limited level.Therefore,the research on port disturbance of intelligent component issure is nessessary.Furmore,the study of protection techqiues is necessary to assit the design and application of the intelligent component.This dissertation investigates the port disturabnces of the intelligent component from the aspects of the disturbance characterization,the coupling mechanism,and the influences of the disturbance,using measuring and simulations.The concrete research contents are as follows:(1)The port disturbance voltage measuemnt systmen is developed based on data acquisition card.With this system,the port disturbance experiments are carried out via the 1100 kV ultra-high GIS test circuit.In the test,the influence of the cable shielding and the cable load to the port disturbance are investigated.First,the disturbance level of the distburance is acquired.Second,the parameters of the disutbracne waveform,such as the rise-time,the duration,the oscillation period,the decaying,are extracted from the experiment data.Furthermore,the port disturbance waveform characteristics in the time-domain and frequency-domain of ultra-high voltage GIS are summarized.Measurements of port disturbance are implemented in 500 kV GIS substations.The disturbance voltage level and the frequency characteristics are obtained.(2)The charateristics of the port disturbance voltage,including the rise-time,the duration,the oscillation period,the decaying,are extracted and analized.Through comparing the characteristics of these measured date and the IEC61000-4-18 standard with regard to the damped oscillation wave immunity test,the differences between port disturbances in real GIS and the standard waveform of IEC are discovered.Some suggestions of the immunity test,especially for the intelligent component in GIS,are provided to impove the IEC standard.(3)The simulation model of very fast transients based on transmission-line network is proposed.A series of research is developed in the laboratory.Fisit,the port disturbance GIS platform is built in the laboratory and the experiment is carried out.Through comparing the experiment result and the data of measured in GIS,the port disturbance from the platform corresponds to the data in GIS from the aspect of the waveform characteristics.It is demonstratd that the lab-experiment via the platform is effective and representative.A circuit model for the platform based on the transmission-line network is porposed and verified.The very fast transients both generated in primary GIS and secondary cable of GIS can be simulated with this model.Furthermore,the influence on the port disturbance,including the cable shielding,the cable load and the GIS grounding etc.,are investigated with the model.At last,the protection techniques for the intelligent component are proposed.