Research On The Anti-EMI Of Microcomputer-Based Protective Relays In The Substation

The microprocessor based protective relay works in serious electromagnetic environment of the Substations. Its immunity level and reliability is more important to the safe and reliable operation of the power systems. The microprocessor based protective relay has exceeded the concept of the traditional protective relay. The trends for the microprocessor based protective relay are the computerization, artificial intelligence, networking, the integration of protective relay, control & measuring and data communication technologies. The computer hardware and software design has been more complicated. on the other hand, the bay -oriented design techniques have widely been adopted in power systems. The conducted and radiated disturbances to the protective relay decentralized installation in switchyard are much more intense. Above all, the microprocessor based protective relay is more susceptible and frangible to electromagnetic compatibility. This article research how to improve the immunity of microprocessor based protection to EMC in this environment: First, the typical feature and coupling channel of disturbance source are considered. And then, discuss the routine ways of anti-interference of microcomputer-based protection, through analyze microprocessor based protective relay misoperation in NingXia grid. Using the electrical fast transient/burst (EFT) equipment and other equipment test PST1200 transformer protection, this paper draws some conclusions about raising anti-interference ability of protection device from test results. First, must block channel of disturbance of common mode, reduce common mode form EMC in the protection device; Second, raise anti-interference ability of sensitive loop circuit; Third, when construct substation, must adopt some ways to decrease EMC.