Research On Power Grid Short-circuit Capacity Measurement Technology

The short-circuit capacity(or short-circuit current)involves the manufacture and selection of primary equipment,relay protection and grid control involving secondary systems,and is a very important time-varying parameter of the power system.With the development of modern power grids,distributed power access to the distribution network has become a trend,and the input and exit of distributed power will have a great impact on the distribution short-circuit capacity,which will bring about the problem of tuning mismatch;Factors such as the transfer of the distribution network and the catastrophic exit of the local power grid will cause the short-circuit capacity calculated offline to keep up with the change of the power grid,and the network reconstruction,self-healing,real-time optimization of the network topology and adaptive control proposed in the smart grid,protection self-tuning and self-inspection technology,need to obtain accurate short-circuit capacity in a timely and reliable manner.For a long time,the power system short-circuit capacity parameters are mainly obtained by offline calculation,while the offline calculation needs to involve the parameters of the entire power grid.Considering the modern of power grid,especially in the field of distribution network,is huge and constantly changing,the calculation of short-circuit capacity will be extremely complicated,and it is difficult to guarantee its timeliness and accuracy.Therefore,after a lot of in-depth and in-depth research,this paper proposes a kind of A new method of measuring short-circuit capacity in the field under non-fault disturbances.By inputting or cutting off the parallel reactive power compensation device of the known capacity on the busbar,the busbar voltage is disturbed,and the effective value of the busbar voltage before and after the disturbance,the phase difference value,and the total active power value and the reactive power value sent by the busbar before the disturbance are measured.In this paper,the measurement principle is derived by circuit theory,and the correctness and accuracy of the measurement method are verified by simulation examples.Then,a standard example model based on RTDS/RSCAD real-time simulation and real-time simulation based on UREP/simulink was built according to national standard examples,and cross-validation experiments were carried out.Finally,the corresponding portable short-circuit capacity tester prototype was developed,and the semi-physical simulation experiment under multiple voltage levels was carried out based on real-time simulation platform RTDS and UREP.The results show that the developed prototype can correctly complete the short-circuit capacity parameter measurement task and ensure The error between the measured value and the theoretical value is within 10%.