Research Of Microcomputer Line Protection Device And Discussion On WSN-based Application In Protection

In a modern electric power system, relay protection device is one of the most important equipment to ensure safe and stable operation of the power system. With the rapid development of computer and microelectronics technology, microcomputer based protection equipment is more widely used in the power system.In this paper, the status and development trend of microcomputer-based protection equipment is analyzed and studied. And as an example, a sort of line protection device which has functions such as protection, supervision, communication, metering and controlling all in one device is taken to introduce the complete design procedure of the whole equipment, based on a series of 35kV-or-below microcomputer-based protection equipments which have been successfully developed and already put into service.This paper introduces the function configuration and the algorithms of microcomputer-based line protection, and it illustrates the research and development procedure of the entire protection device respectively in design of hardware system and software system. In the design of hardware, a master-slave CPU structure is applied: Microchip Company's DSC processor dsPIC30F6014a is used as the control processor core and PHILIPS Company's MCU P89C669 is applied for human-machine interface. The hardware design adopts a composititon of three plug-in circuit boards: CPU main board, digital output board and human-machine interface board. They together integrate all the functions of AC input unit, digital input unit, communication unit, operation circuit unit and human-machine interface unit. This paper respectively introduces the hardware design of the three plug-in circuit boards as well as the software design procedure for CPU main board and human-machine interface board. The entire protection equipment proves well in comprehensive performance under analysis after function tests.With the rapid development of computer and communication technology, wireless sensor network is more and more applied in the power system. The paper studies the development status of wireless sensor networks and analyzes the feasibility of using wireless sensor networks in the power system. In addition, it proposes a directional busbar protection scheme based on wireless networks and microcomputer-based protection and it expounds protection principle and system structure of the scheme. At the end, it evaluates the advantages and disadvantages of the scheme and prospects its application in the near future.