The Design And Development Of A Differential Protection With Load Testing Software

Transformer in power system shoulders the risk of changing voltage to each grade.To be the most quickly transformer protection, differential protection could reflect fault in the first time and make a judgment to select the trip, thus to removal of the fault, and to guarantee the transformer’s normal operation. Algorithm of differential protection is diversity, for example, differential protection, phase segregated differential protection,sub-side differential, differential of self-produced zero sequence, differential cell. One side, different differential protection has different CT combinations to calculate, and reflect to different range, requires absolutely correct of every CT wiring, making crucial with transformer load test when put into operation, the other side, manufacturers of various protective devices have different understanding and different algorithms to each differential protection, therefore, when test the transformer with load in field, the difference among the algorithm, and the difficulties of computing, brought so many difficulties to the field staff for the calculation and understanding.Though the analysis on the characteristics of the malfunction-voltage, and the malfunction-current in power system, series of differential protections are introduced,and the corresponding protection configurations under different fault conditions. Then discuss in detail the composition of differential transformer protection, CT usage,principles of angle change, amplitude correction methods. By understanding the summary, has been clear about the various protection device manufacturer for all kinds of protection principle and algorithm of understanding, but also get the theoretical basis to develop software. Later, the article also introduces the main transformer differential protection with load test software development process, shows some diagrams of the software, and introduces how to get convenient from the software. Finally, using the220 k V Shuang QZ substation main transformer on-load testing of a real data, testing software, and find out that the diagrams are correct.After analysis and tests showed, with the birth of transformer protection software,there will be the use of on-site operations personnel to find the point of failure quickly and efficiently, hence practical field, end of the paper noted that the development of a load test program which can be used in the portable device, Will be more easier to use in field.