Research On Structure And Control Method Of AC Current Electromagnetic Tripping System With Two Tripping Values

In order to meet the concept of “Smart grid”,improving the reliability,security,economy and efficiency of the power grid is the current direction of power development in China.As the core component of distributing current,detecting fault and implementing protection,the circuit breaker in the smart grid can be said to be in the forefront of the Times,as the core component of the circuit breaker,the electromagnetic release is the guarantee of its intelligence.Therefore,the intelligence upgrade of the miniature circuit breaker can be realized by upgrading the release device.Because the traditional circuit breaker only realizes the short-circuit instantaneous protection,can not realize the short-circuit short-circuit delay protection.In order to solve this problem,the structure and control strategy of the new electromagnetic release are studied in this paper.Main work:Firstly,based on the application background of circuit breaker and the development status of intelligent tripping device,the potential advantages of double-winding AC electromagnetic tripping device in the application of circuit breaker are analyzed,and the development characteristics,structure rules and working principle of double-winding AC electromagnetic tripping device are summarized.A double-winding AC electromagnetic tripper was designed.The circuit breaking of the control winding can meet the short-circuit delay requirement of the circuit breaker.The influences of spring reaction force characteristics,excitation coil action characteristics and the structure size of the tripper on air gap permeability,leakage permeability and coil resistance were analyzed.Then,according to the different trip analysis result of the influence of structure parameters on the performance,the design,according to the structure of the trip to profile analysis,draw the circuit and magnetic circuit,the relationship between the formula shows that theoretical basis,and the control of the control winding moment and tripping force magnetic circuit model is established using MATLAB verify analysis,The relationship between tripping time and tripping force of the control branch under different conditions is obtained.The results show that the design scheme meets the design requirements,and the selection of the control time of tripping force gets a clear conclusion.Finally,considering the operating environment of ZSI zone control of circuit breaker,the break time of control winding of the designed double-winding AC electromagnetic trip is calculated and analyzed.In order to compare the advantages of the two-winding AC electromagnetic trip with the traditional trip,the design of Hall switch element is introduced to control the break of the control winding loop.Simulink in MATLAB is used to establish the model,and the system waveform is simulated according to the open circuit and short circuit of the control coil at different times.The excitation current and secondary current of the circuit breaker are compared and studied.The results show that the double-winding AC electromagnetic tripping device has short circuit delay control which is not found in the traditional tripping device.Faster reaction time than thermomagnetic release.That is,it reduces the risk of circuit breaker rejection and misoperation,improves the operation reliability of circuit breaker,and makes the intelligent small circuit breaker go a step forward.