| The high voltage switch industry has obtained further development with the national attention increasingly in the electric power industry, playing a key role in the whole power supply system, and it is a key link of the smart grid development. Traditional ferromagnetic transformers are used to measure high current in high voltage switch cabinet, with the disadvantage of their low accuracy of measurement and narrow frequency band, at the same time, they also have hysteresis phenomenon. And they can’t meet the requirements of digital, real-time measurement. A new kind of technology is needed to satisfy the requirements of the smart grid current measurement.Primarily, a theoretical research has been conducted in current measuring for Intelligent High- voltage Switch Cabinets’ application, and magnetic sensor current measurement method is proposed compared the mainstream of the current measurement technology with each other. At the same time, the measurement topology matrix is designed, the mathematical model is deduced and the current solution matrix is obtained. To test the excellence of the measurement, current measurement experiments are built in the range of 0~1200A. Through the experiments results, MMLP57 H magnetic sensor was chosen to be the best measurement sensor, its accuracy reached to 2%.Secondly, three dimensional numerical model of the high- voltage switch cabinet busbar is built. Edge element method is used to calculate the electromagnetic field distribution.Thirdly, measurement topology optimization experiment is designed. Internal magnetic field is measured point by point in K YN28-10 k V high- voltage switch cabinet. Verify the correctness of the three dimensional simulation models by the measurement data, and finding the best measurement placement after 3 aspects: horizontal position, vertical position, and plane position. Comparing the experiment results before and after optimization, the measurement precision after optimized can reach to 1.1%. Analyze the relationship between the busbars placement and the magnetic field distribution, and redesign the busbar chamber size according to the related standard.At the end, the anti- interference design is conducted. By analyzing the interference sources and vulnerable to the main part of the high voltage switch cabinet busbar chamber, and taking measures from 4 aspects: the magnetic sensor PCB, embedded system shielding case, busbar chamber shielding and weak signal system distribution. Calculate the shielding effectiveness to measure shielding effect that the shielding plate in different positions by the experiment data. For weak signal system, using double layer shielding wire, to keep signal from interfering by electromagnetic interference. |
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