Research On Digital Protection Device Of Power Transformer Base On DSP

The power transformer is a very important equipment in power system. It will relat to the electric power system directly can continue a stable work whether its safety circulate or not. The traditional protection and monitoring system of power transformer is usually scattered single-chip module structure, this structure leads to the calculation speed slowly and makes it difficult that the structure will content with the high requirement of speedy and real time. The paper aims for these problems and incorporates with a real project to research and develop a protection system of power transformer based on DSP.Firstly, the author discusses the situation and problems of protection system of power transformer at present, especially assays and studies the shorts of hardware and development environment, then concludes that selecting DSP as the microprocessor has important meaning. Secondly, author makes detailed study on the main aspects of protection principle of power transformer (including inrush current,the unbalance electric current , differential protection, zero sequence protection etc.) For satisfying the high request of fast and credibility of the protective system,the device adopts double the structure of the CPU plug-in, main protection and spare protection function the concentration completes on a piece of DSP, the communication function at another a piece of DSP complete, protecting DSP samples independently and completes all digital filter protection calculate way and export logic, but supervise and control of the DSP completion general stard-up of device and man-machine interface, backstage to correspond by letter function. This raises the fast for device by so doing, promise to equip not because of supervise and control the CPU plug-in the any spare part damage but cause the protection mistake action.Fourier algorithm is precise and can filter the wave, calculation the quantity is just right by the contrast among the capability of common algorithms, Fourier algorithm can calculate the solid and falsely department of fundamental wave, this can compute negative electric voltage zero electric voltage power and the power direction with electricity quantity.The protection device was experimented by simulated method and the result testified that the device has high reliability, high correct action probability, high measurement precision, high anti-interference ability etc.