| Gas insulated switchgear(GIS)has been widely used in power grid due to its advantages of small space occupation,less environmental impact,less maintenance workload,high operation reliability and low operation cost.There will be high residual voltage after UHV GIS bus switch opening,which may lead to serious transient overvoltage and affect the security of power system.At present,the research of GIS bus residual voltage mainly focuses on the influence of transient overvoltage amplitude,while the research of bus residual voltage attenuation characteristics and superimposed impulse voltage is less.The main contents of this paper are as follows:(1)A test platform for GIS bus residual voltage attenuation and superimposed impulse voltage is built.The platform is designed with several observation windows and voltage measuring devices to observe the test discharge phenomenon and measure the test voltage;A GIS bus residual voltage measurement device based on the principle of electric field is studied;A hand hole capacitance sensor measuring device is installed to measure the bus transient voltage.The attenuation characteristics of GIS bus residual voltage with time under different polarity,amplitude and temperature are tested.The test results show that the attenuation characteristics of the residual voltage of different polarities are similar;the higher the amplitude of the residual voltage,the longer the decay time;the higher the temperature,the shorter the residual voltage decay time.(2)The equivalent circuit of GIS bus residual voltage attenuation is established.The calculation model of GIS bus residual voltage attenuation is derived from the equivalent circuit.The attenuation characteristics of GIS bus residual voltage under different number of pot insulators and different bus length are calculated by using the model.The calculation results show that: the more Basin insulators,the shorter the residual voltage decay time;the longer the bus length,the longer the residual voltage decay time.(3)The test method of residual voltage superimposed impulse voltage in the suspension state of the busbar is proposed,and the positive/negative residual voltage superimposed positive/negative lightning impulse voltage and the superimposed positive/negative operating impulse voltage test in the suspension state are carried out.Each combination is carried out 4 times A total of 32 tests were carried out.The test results show that in the 16 residual voltage superimposed lightning impulse voltage tests,two basin-type insulator flashovers occurred,and the residual voltages were all negative.In the 16 residual voltage superimposed operating impulse voltage tests,no basin-type insulator flashover occurred. |
