A Study On Measurement And Control System Of Intelligent Synchronous Vacuum Circuit Breaker

As one of the important electrical equipment, the circuit breaker controls, adjusts and protects power system. The reliability and intelligence degree of circuit breaker greatly influence the stabilization and automation degree of power system. With the continuous expanding of power grid, consumers demand higher power quality and dependability. The high quality of power is indicated by the stability of voltage and frequency, distortion rate of voltage, transient process and so on. Frequent operation of circuit breaker causes a lot of operating transient process which directly affect power quality in distribution power system. Because of the increasing technology progresses and remarkable advantages of Vacuum circuit breaker, it is used more and more widely in distribution power system. Therefore, the study of intelligent synchronous operation of vacuum circuit breaker, aiming at suppressing operation of over-voltage is of great practical significance for safety operation of power systems and improvement of power quality.Based on the analysis and summarizing of research status of circuit breaker intelligence at home and abroad, this paper makes a theoretical analysis on operating over-voltage produced by switching vacuum circuit breaker, studies the influential factor for acting time of permanent magnetic actuator and presents a feasible approach to accomplishing the intelligent synchronous operation basedon DSP and artificial neural network. The calculation method of the electrical parameter of power system is also proposed.In connection with this subject, the main contents are described as follows:1. A theoretical analysis on operating over-voltage of vacuum circuit breaker is made in detail. The reason and suppressing means to operating over-voltage are described in all situations. Over-voltage when switching unloaded transformer, power capacitor, unloaded transmission lines is discussed respectively.2. The working principle of bio-stable permanent magnetic actuator is introduced in this paper. A feasible approach to making mathematical model to predict the closing and cutting time and the implement method of the model with DSP are proposed, based on analyzing the factors which influence the acting time of permanent magnetic actuator and on the use of artificial neural network. The means to predict zero point of signal and the whole project for synchronous operation are proposed as well.3. The sampling and calculation methods of the electrical parameter in power system are proposed. In this paper, a group of filter operator is introduced to estimate the parameter of decaying DC component online. A technique to calculate the fundamental frequency and harmonics component in the signal is proposed based on evaluation of the decaying DC offsets. The data windows just need one fundamental cycle, so this technique has high speed. In theory, this technique is an accurate algorithm.4. Making use of MATLAB software, operating over-voltage caused by closing unloaded transformer is simulated. A mathematical model is built to predict the closing time on the base of MATLAB artificial neural network tool. Simulation results adopted traditional DFT and this technique show the effectives of this technique to calculate the electrical parameter in power system.This paper proposes the method of intelligent synchronous controller of circuit breaker with permanent magnetic actuator, which adopts a fast algorithm to deal with signal and combines DSP and artificial neural network. It contributes, to some extend, to the improvement of power quality and the implement of integrated automation of distribution power system.