Design Of Intelligent Release Based On Early Detection Technology

Frame circuit breaker is one of the most important control and protection devices in power system.Its protection function directly affects the safe operation of power system.With the development of power system,the circuit breaker industry and its intelligent level will also develop.The intelligent release as the core control component of the frame circuit breaker,controls all the action of the frame circuit breaker,and therefore its performance directly determines the control and protection function of the frame circuit breaker.The short-circuit breaking capacity of the frame circuit breaker is an important indicator of the performance of the frame circuit breaker,in which the breaking time is an important manifestation of the frame circuit breaker short-circuit breaking capacity.For a frame circuit breaker,the time of completing a short circuit breaking is composed of two parts,inherent breaking time and arcing time.The inherent breaking time includes the current acquisition time,the controller processing time,and the mechanism action time.Based on this,this paper focus on the controller processing time,to shorten the time,the target is from the original 3?5ms shortened to 0.3?0.5ms.This paper mainly completed the following work:1.The advantages and disadvantages of several early detection algorithms for short circuit fault are studied and compared.Finally,the morphological wavelet algorithm is chosen as the algorithm of short circuit fault detection for intelligent release.A morphological wavelet algorithm combining the generalized shape open filter and the wavelet packet decomposition is established,which is used to identify the short circuit fault of intelligent release.2.Using simulink to establish a circuit model from the power station to the substation to the user,to simulate the waveform of the current in the circuit when the short circuit fault occurs,and save the current data for the analysis of the threshold value of the short circuit fault function decision value,simultaneous as waveform input of short circuit simulation experiment.3.The hardware circuit of the control board and panel of the intelligent release is designed.There are power supply module,signal conditioning circuit,analog trip circuit,pulse width detection circuit,release control circuit and micro processer and its peripheral circuit,key circuit,display drive circuit,and so on.Designed a software program for intelligent releases,with short circuit protection,overload protection,undervoltage protection,and so on.Completed the basic functions of hardware and software debugging.4.Use the waveform generator output short-circuit current signal and overload current signal,the signal input to the intelligent release control board to complete the short-circuit simulation experiment and overload simulation experiment.5.In the laboratory with a large current generator to complete overload experiment,distribution short circuit system to complete the short circuit experiment.Through the simulation test and high current test combination,from the short circuit fault to the intelligent release of the trip signal issued time between 0.2?0.5ms,overload protection action time and theoretical calculation time error within ±10%to meet the requirements.In this paper,the early detection algorithm is applied to the short circuit fault detection of the circuit breaker,which greatly shortens the detection time of the short circuit fault of the circuit breaker and improves the short circuit breaking capacity of the circuit breaker.This paper designed the intelligent release hardware and software,through experimental verification to achieve the desired goal for the follow-up product laid a good foundation.