Research On The EMC Of Detail Micro Computer-based Relay Protection

Relay protection device is one of the important secondary equipments of power plant and substation. The degree of relay protection device has great influence on the stability of power grid and the safety of the other primary equipments. Whether misoperation or misstrip occurs to protection device both lead to serious accident and economic loss. Digital relay protection device which is one kind of digital electronic equipment has high-sensitivity and great capability of weak signal receiving. But at the same time, relay protection device have the current to be placed the locale and distributing installed dispersedly, which worsened the electromagnetic environment. Therefore, ElectroMagnetic Compatibility (EMC) has aroused more and more recognition of the relay protection device producing plant and operation and maintenance department.Design on EMC of digital relay protection device generally adopts Test and Modification Method and System Flow Method. Test and Modification Method only modifies the problems which are found in the course of testing the prototype at the end of production development until the design satisfies the request of electromagnetic compatibility. Test and Modification Method have benefits of convenient operation but have characteristics of high difficulty, long period and high cost. However, System Flow Method introduces correct strategy of EMC design and the inhibitory method is actualized accurately. Using System Flow Method, the late EMC problem is little and easy to solve so that shortens the research period and reduces the cost. However, System Flow Method has no method to distinguish the relative important degree which can insure the output ratio maximization. Therefore, in this paper, Analytic Hierarchy Process (AHP) of decision theory has been introduced. The process of the design on EMC of digital relay protection device has been optimized by using AHP which have confirmed the priority weight of several important stages in the process of EMC design of the digital relay protection device and provides guidance for the whole design process.In this paper, the characteristics of electromagnetic disturbance signal which influences the digital relay protection device seriously have been analyzed at large and the design method also has been deep analyzed. The weight determination of each stage of the of micro computer-based relay protection device's EMC design flow has been completed by using AHP which makes clear the important degree of the whole design's each stage. On this basis, the EMC control technology and design method have been used in the hardware platform development of the equipment named XR200, which is one kind of serialization productions of Xi'an Xirui Protection and Control Co.,Ltd. This serialization productions of digital relay protection device have passed the national EMC test and have been launched into market, and have realized the request of the EMC successfully which have been receiving favorable economic benefits.