Research On Anti Over-ride System For High-voltage Power Grid Of Coal Mine

The safety and reliability of power supply system not only affects the efficiency of coal mine production, but also indirectly affects the safety of coal mine staff’s life. In our country, the high voltage power supply system affected by various factors in coal mine often appears the switches of superior substation tripping phenomenon due to lower substation feeder fault in the actual operation of the process, which is called "leapfrog trip". Statistics show that most phenomenon of tripping is caused by short-circuit fault and leakage fault. As a result, it is of great significant to research into the causes of the leapfrog trip and take corresponding measures to avoid its occurrence for improving production efficiency and reduce casualties.According to the characteristics of the coal mine power networks, this paper firstly analyzed the current distribution characteristics after short-circuit fault and leakage fault, meanwhile studied the real reason for two kind of trips and analyzed similarities and differences of them based on the current protection configuration theory. The paper put forward anti leapfrog trip protection scheme based on Boolean algebra on the basis of the similarity for two kind of trips. In order to remove the fault as soon as possible, the high voltage switch is divided into three categories, and the corresponding logic judgment expressions for each type are provided, meanwhile described the principle of anti tripping protection base on specific fault.In order to guarantee the reliability of anti leapfrog trip system and solve the problem that power system can not be restored fastly because fault point is not found, backup protection based on perception neural network is equipped for short circuit fault and backup protection based on BP neural network is equipped for leakage fault in addition to main protection. There are some shortcomings of BP neural network algorithm, such as slow convergence, easy to fall into local minimum, and uncertain structure, so an improved BP neural network algorithm is proposed in the paper. The fault characteristic value which is easy to identify after fault is selected in the improved algorithm. By theoretical analysis and building model in Simulink, the advantage of the improved algorithm is verified.This paper finally designed a system of anti leapfrog trip, which are STM32F417 as the core of coal mine high voltage intelligent comprehensive protective device, Hollysys PLCLM3105 as the core of logical judgment anti leapfrog main protection device, and IPC as the core of centralized control anti leapfrog host. Program flow diagrams and key technologies of the system are also given in the paper.