Research On Intelligent Control System Of Low Voltage Molded Case Circuit Breaker

Breaker is a kind of switch equipment widely used in the Electric System,whose stability and intelligence may pose large effects on the Electric System.With the arising of intelligent power grid,its intelligence,especially the intelligence of its controlling system,is becoming the hotspot of studies.Nevertheless,conventional intelligent automatic controlling system had a lot of disadvantages,i.e.,the setting of protecting parameters is not flexible,integrate harmony protect possesses limited technique,fault prediction is not employed.There are many types of faults can be researched;and single-phase faults are most ordinary and pose largest threat,so it was cited as the key of the research.Meanwhile,in order to extend the protecting range of breakers,zone selective interlocking technique is employed.Details of research are as following:Chip TMS320F28335 is used as the core processor of the design.A Gray Dynamic Prediction Model is raised,aiming at a problem that updated data cannot be used efficiently.This problem is attributed to inappropriate data iteration in short-circuit peak current prediction of the Gray Prediction model.The new model improves the efficiency of prediction by employing dynamic data iteration.Further,model of short-circuit fault simulation was built in Matlab/Simulink,which various waves are enabled to be observed when short-circuit with different initial phase angel happens.At last,initial phase angel,short-circuit current,the result of Gray Dynamic Prediction Model and its comparative residual error are set as the inputs of training BPNN(Back Propagation Neural Network);and Gray BPNN Short-circuit Peak-current Prediction Model is built.Zone selective interlocking protection were employed to avoid large range power-off,but conventional three-segment current protection was reserved.Zone selective interlocking protection is the highlight of the development of intelligent power grid in the near future.its employment in this research is an innovation.Modbus enables the communication between controlled units and control center;and it is precondition of zone selective interlocking protect as well as the symbol of breaker's intelligence.The circuits of concentrator and slaves are designed in the research;and they passed the tests of communication distance,communication baud rate and stability.Finally,comprehensive tests are given to the circuits and software of intelligent control system by a testing field.Results suggested that the unlock time of fundamental three-segment current protection subjects to national standards;Gray BPNN Prediction Model shorten the time that system recognize when faults occur.Tests were given to the function of zone selective interlocking protection.Results suggested that it achieves the protection of whole range of power grid,which will the precondition of field tests.