Research Of Zone Selective Interlock In Low-Voltage Power Distribution Based On Modbus/TCP

In the traditional low-voltage power distribution system,there has been an old open problem that caused by blackouts at the area have no faults when large short-circuit current fault occurs at the power distribution system and at the same time the circuit breaker without tripping selectively. This problem has been bothering the intelligent process of low-voltage power distribution system much more years. Fortunately in 2009, our country put forwards the concept of "Smart Grid", its main goal is to ensure the reliability and continuity of power supply for the low-voltage power distribution system, it provides the opportunity for the development of low-voltage power distribution system,also it is an important mean of achieving intelligent selective protection.In recent years, with the development of computer technology, communication technology and electronic information technology, our people pay more and more attention to the Zone-Selective-Interlock protection technology, it is a new selective protection technology in low-voltage power distribution system. Continuous and reliable power supply of low voltage power distribution system relies on timely protection of low voltage circuit breaker when the system occurs overcurrent fault.But the current problem that our intelligent circuit breaker is short of coorperating with each other is more and more prominent, in order to realize the Zone-Selective-Interlock protection technology. this paper puts forward a kind of Ethernet communication technology. It discusses the advantages and performance of Ethernet communication technology in the field of industrial control, also it introduces the characteristics and communication performences of low-voltage power distribution system, it studies the real-time performance of Modbus/TCP protocol. Theoretical analysis is conducted on the establishing of Modbus/TCP transportation layer and the data transmission time of Modbus application frame over Ethernet. According thees,It proposes to design Zone-Selective-Interlock control unit by using Ethernet communication technology(UDP protocol) and application of embedded system technology,which is innovative idea that establising the Zone-Selective-Interlock experiment system.Finally, the Zone-Selective-Interlock experiment system satisfies the communication needs of intelligent power distribution system. It concludes that Modbus/TCP has better real-time performance and satisfies the communication needs of intelligent low-voltage power distribution equipments and meets needs of zone selective interlock protection mechanism. It is an efficient solution for accomplishing our intelligent low-voltage power distribution system.