An Approach to Improve Measurement Accuracy for Electric Power Fault Recorder

Electric power fault recorder is considered to be an important secondary device in modern electric power system. The data recorded by fault recorder has become basic and reference material for future calculation, analyzing and decision making. However, the measurement accuracy of fault recorder has rarely received much attention in the past, which could cause the applications that are based on the recorded data to obtain inaccurate results, and thus tend to weaken the deserved reference value of the recorded data. To improve the measurement accuracy of fault recorder, the input-output property of fault recorder´s analog channels is studied in this paper. The studies show that the linear expression can not accurately express the relationship between input and output of analog channels. Careful examination of fault recorder´s sampling data reveals its input-output relationship is a slightly non-linear expression. In order to reduce the impact of non- linearity, the best fitting curve and best segmented fitting curve are proposed to replace the linear expression in this paper. The test results on actual fault recorder show that the presented approach can greatly improve the measurement accuracy, even in a large measurement range.