Research On Short Circuit Current Limit Optimization Based On Zero Loss Depth Current Limiting Technology

In response to the current situation in the development of modern power systems,the short circuit current level is increasing and the current capacity of circuit breakers is insufficient.This avoids the problems of large energy consumption,high cost,complicated technology,and large volume of traditional current limiting devices.It is applicable to the fast switching type zero loss active current limiting device,which may be expected to alleviate the current rapid growth of short circuit current in the domestic power grid.The main work of the thesis is as follows:Firstly,the current limit requirements of existing power systems and the advantages and disadvantages of existing current limiting technologies are analyzed.The design,key technologies and optimization methods of zero-loss active deep current limiters are proposed.Among them,the use of inverted CVTs is directly performed by 330 kV lines.The operating power of the device is obtained,and a constant current is used to ensure the stable power supply of the device.The design of the current limiting unit adopts a short-circuit operation and current limiting scheme where an intelligent high-speed switch is connected in parallel at both ends of a current-limiting reactor.After a current limiting unit is connected to a branch requiring current limitation,the fast vacuum circuit breaker of the current limiting unit is opened and the reactor is connected to the current limit in accordance with the occurrence of the maximum short-circuit current;and,in order to reduce the power system band,The loss from the use of eddy current fast switching technology has accelerated the input and output of the device.Then,the performance of the research and design device was tested,including laboratory tests and the test of the running of the hanging network.The current limiting depth,loss,switching action,accuracy and rapidity of breaking,port pressure resistance,etc.were performed.Comprehensive testing.Finally,an optimization method for the installation location and type selection of the device is proposed,and the actual network verification device is used to verify the current limiting effect in the actual grid operation.The zero-loss active depth limiting device can flexibly input the current limiting unit according to the short-circuit current level and has an expandable line,which can provide a new measure for the current limiting of the rapidly developing power system.