Research On CVT Live Abnormal Detection And Application

In various substations of the power system,Capacitive Voltage Transformer(CVT)is a special form of converter.The CVT is installed on each voltage level bus or each outlet interval.The high voltage is converted into a secondary low voltage and the high voltage is isolated by the principle of capacitor voltage division,and is used for relay protection,automatic devices and measuring instruments in the station.At present,the operation and maintenance methods of CVT in China Southern Power Grid Co.,Ltd.are mainly divided into Class A overhaul,Class B overhaul and Class C overhaul.Through these maintenance methods,the substation maintenance personnel can find and deal with most of the defects,but there are quite a few defects that cannot be effectively diagnosed until the capacitive voltage transformer is damaged or even burned.According to the operation of CVT in A Power Grid and considering the advantages and disadvantages of daily operation and infrared thermal imaging detection,this paper proposes a set of secondary voltage monitoring strategy,which can make up for the vacuum period between two power failure pre-tests.It can detect infrared thermal imaging before it can ensure reliable power supply(no power failure),and can detect it in the initial stage of CVT internal defects,and then verify and eliminate hidden dangers through other traditional pre-test and maintenance methods to ensure CVT,to ensure safe and reliable operation of CVT.Based on the analysis of the current status of operation and maintenance management of capacitive voltage transformers in A Province,this paper combines the fault instances of some capacitive voltage transformers in the region and even A power grid to carry out theoretical analysis on the examples.As a result,an early warning rule is proposed for the change of the secondary voltage of the capacitive voltage transformer at the present stage.The early warning rule can remind the maintenance personnel during the incubation period of the defect,provide more accurate and effective information for the maintenance personnel during the maintenance and inspection process,help reduce the unreliable power failure to ensure the reliability of the power supply,and can process related processes in the early stage of the defect repair.Improve the economic and practicality of the products while improving the ability of the regional power grid to operate normally and safely.