Research On Full-rated Voltage Synthetic Making Test System For High Voltage Switches And Their Applications

The primary background of this research is based on synthetic test of high-voltage switches. The methods of test and the role their play, in the process of new product design and development, are summarized. The International Electrical Committee (IEC) standards and national standards on synthetic test of high-voltage circuit breaker are taken as the guidance of our research. The overall objective of this work is as following: the test circuit setup, of synthetic making test and making performance analysis of high-voltage circuit breaker, the manufacture of current source making device and correlative theory for it, design and actualization of the measurement and control system for synthetic making test at full-rated voltage etc. The research can provide the theory and test groundwork for making performance assessment of high-voltage switches.The dielectric strength characteristic between electrodes is strongly impacted by making operation of circuit breakers, and by the closing and latching capability of their actuators. In the first, through the analysis of closing and breaking process, the arcing energy model is educed. The rate of dielectric decrease strength (RDDS) and its variation rate (K_RDDS) are presented. The relation between making phase of applied voltage, the maximum and minimum arcing time, pre-arcing energy together with other parameter and K_RDDS are analyzed quantitatively. Finally, the thermo-dynamic process effect of making short circuit current on subsequent breaking operation is discussed. Thus the requirement for making capability of high-voltage switchgear can be achieved.The key to perform synthetic making test at full-rated voltage is the making device of current source, which should have the capability withstand the high-voltage between electrodes, high current through it and to act rapidly. The launching device of current source, which based on triggered vacuum switch (TVS) and fast vacuum circuit breaker (FVCB) to form the basic unit, and synthetic making test circuit at full-rated voltage are introduced in our research. In order to research and optimize the triggering performance of TVS and actuator of FVCB, lots of simulation and experiment have been carried out. As a result, the triggering time delay of TVS is at microsecond level and the closing time of FVCB is less than 8 ms, that meets the demands of making the current source fastly and stably.Simulation and experimental analysis are carried out on the making current transfer process between TVS and FVCB. The short circuit current expression in TVS and FVCB at each period is presented, which is influenced by factors such as arc voltage and branch resistance, inductance in TVS and FVCB respectively, and the pre-arcing and closing moment of FVCB are also the contributing factors for it.In order to meet the equivalent condition and performance of synthetic test with direct test, voltage and current stress must be satisfied with requirements of test standard, the closing phase of applied voltage and the phase difference between applied voltage and making current must be restricted in the allowable range. Based on the synchronous closing technology, the phase of applied voltage and making current is detected in real time, so above mentioned requirement can be fulfilled. The purpose of the criterion on whether the launching device of current source to act is to reduce the erosion in the tested switch and the launching device, so the validity and successful rate can be guaranteed.The control strategy and its realization, based on the launching device and synthetic making test circuit presented in this paper, are emphatically expounded. The main factors impacting the control accuracy are analyzed, and the compensate measures are also proposed. The measurement and control system of synthetic making test for high voltage switchgear is developed, which adopt pre-arcing current in the switch under test and the phase difference between applied voltage and making current in the range of 90±27°as the criterion of whether the launching device of current source to act.Finally, the prototype of the proposed launching device of current source at rated parameter 110kV/63kA and the measurement and control system for synthetic making test are fulfilled in our research. Actualizing scheme for full-rated voltage synthetic making test system at rated parameter 550kV/63kA is presented. The functional and reliability test has been carried out at Xi'an High Voltage Apparatus Research Institute. The representative phase difference between applied voltage and making current when making at the crest of applied voltage is±800μs, which is prior to the phase differences±1.5ms recommended in IEC and national standard. The results of the experiments indicate that the launching device of current source and the measurement and control system for synthetic making test perform reliably. The research and design target of this paper are obtained successfully.