Development Of The Intelligent Controller Of The Feeder Switch

The low-voltage feeder switch mainly adopts the underground power supply system and the intelligent protector is the core part of the switch, which conducts processing and analysis on lots of information collected from the outside and further decides to turn on or turn off the switch. Though the protector has been developing towards intelligence from non-intelligence, its reliability and sensitivity can’t yet satisfy the requirements, and malfunction and refused action will occur frequently, which has brought hidden danger for the safety production of coal mine. With the development of underground mechanization, intelligentization and modernization of coal mine, the advancement of voltage grade and the increase of power supply distance have also put forward higher requirements to the performance of the intelligent protector.Firstly,this paper elaborates the development tendency of intelligent protectors and their research trends both at home and abroad to get a deep understanding of several protection principles of the intelligent protector of the low-voltage feeding switch like the earth leakage protection of additional DC, overload and selective leakage protection, phase-sensitive protection, over-voltage and low-voltage protection etc., and puts forward a suggestion to adopt two AVR atmega128 single chips to realize all the functions of intelligent protectors. One is responsible for collecting external data and the other one is responsible for displaying the collected data, both of which carry out communications through the serial port. Because of the increase of the cable distributed capacity, the traditional selective leakage protection has become ineffective; therefore, a new kind of selective leakage protection principle,double-zero sequence detection method is developed. Because there exists a protection dead zone about the widely used phase-sensitive protection, a new short-circuit protection detection method, multiphase detection method is researched and developed based on the phase-sensitive protection.Secondly, it puts forward the hardware and software design of intelligent protectors, the former of which mainly explains the design of the selective leakage protection circuit and short-circuit protection circuit and meanwhile proposes the anti-interference measures for hardware and software.Finally, the reliability and sensitivity of the double-zero sequence selective leakage protection and multiphase short-circuit protection are verified through experiments, which improve the underground work efficiency and provide a guarantee for the underground power supply system.