Early Detection And Zero-cross Prediction Of Short-circuit Fault For High-voltage Circuit Breaker Interrupting Technology

With the development of power system on the direction of higher voltage and larger capacity,the amplitude of short current that circuit breakers interrupt is increasing.It’s unwisely to increase the breaking capacity unlimitedly.Applying phase-controlled interrupting technology to short current with the main contacts micro arc breaking on the zero moment may further improve the breaking capacity and the electrical life of the circuit breaker.This thesis studies on short-circuit fault phase-controlled interrupting technology on high-voltage power system of which key lies in the fault detection and zero-cross prediction of short current.It mainly contains those contents as followings:(1)Building 110kV high-voltage transmission line short-circuit fault model based on Matlab/Simulink,wavelet transform early detection technology is applied to transmission line for fault fast detection.The rapidity and reliability of wavelet transform is proved by the model besides simulating the switching overvoltage and inrush current in the power system.(2)This thesis puts forward a geometric dc component recursion fault current prediction algorithm to predict the short current zero-cross moment,which needs about half a cycle time for sampling.The algorithm can accurately predict zero-cross moment even the short current contains high times odd harmonics.The calculation process is simple without reckoning specific parameter values.By the model simulation and fault data verification,the algorithm zero-cross point error is less than 0.5 ms which satisfies the requirement of phase-controlled interrupting technology,(3)Combining early detection of short-circuit current with zero-cross prediction,an early fault detection based geometric dc component recursion fault current prediction algorithm is proposed.Realize the early detection phase-controlled interrupting technology based on NI Compact-RIO measurement and control system which is proved by the function/arbitrary waveform generator HP33522A.(4)This thesis analyzes phase-controlled interrupting operation mechanisms while comes up with fast breaking technology base on the eddy current repulsion to decrease the scatter of the mechanism.The feasibility of this technology proves by the experiments.In conclusion,the thesis introduced early fault detection technology into high-voltage power system for faster fault identification.It put forward the early fault detection based geometric dc component recursion fault current prediction algorithm to realize phase-controlled interrupting technology.It came up with the fast breaking technology and verified which laid the theoretical and technological foundation for the further development.