Research On Synchronization Control Method Of Circuit Breaker

The method of improving the ability of the circuit breaker to break the short-circuit current and extending the service life of the circuit breakers has become a hot research direction for the intelligent development of switching appliance.At present,synchronous control technology has been put into practical use in the control of capacitors and reactors,the research on synchronous breaking short-circuit current is still in the experimental stage,which has research value.Synchronous switching of circuit breakers,as one of the promising research area of smart smart electronics,can effectively enhance switching capability of circuit breakers while reducing electric arc damage.To achieve synchronous control,separation and reconstruction of short-circuit current is required for prediction of zero crossing of short-circuit current.This thesis analyzes two most commonly adopted zero-crossing prediction algorithms,parameter estimation using least square method and enhanced Fast-Fourier-Transformation(FFT)method,with simulated data.The simulated data are firstly obtained from the proposed single-phase short-circuit model.Short-circuit currents with DC attenuation component and harmonic component are then synthesized with Gaussian noise with different SNR before being digitalized.Finally,by simulating grid frequency variation,testing data for zero-crossing prediction can be then obtained as distributed short-circuit current series from synchronized and asynchronized sampling.In addition,two aforementioned algorithms are also tested for waveform analysis and zero-crossing prediction with real short-circuit current data obtained from experimental short-circuit platform.Experimental results suggest that enhanced FFT algorithm is accurate than least square parameter estimation method.However,it relies on excellent stability from grid frequency as well as strict requirement on SNR of digital measurement systems and valid bit depth of ADCs.On the other hand,least square parameter estimation method demonstrates better noise and interference immunity.Through the simulation and experimental comparison,the respective use ranges of the two zero-point prediction algorithms are determined.In practical applications,reference can be made to the selection of a suitable zero-point prediction algorithm.