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Detection Technology

DC high voltage generator test efficiency

time:2021/3/10   source:华天电力  reading:586 time

With the large-scale deployment of DC transmission projects, the number and frequency of DC high-voltage generators have greatly increased. In order to improve the efficiency of DC high-voltage generators, it is necessary to increase the speed of polarity switching.

The omnipolar conversion of the DC high voltage generator involves a series of processes such as generator voltage reduction, grounding, silicon stack polarity switching, grounding and boosting. Each step of the polarity switching process requires a lot of time. In order to shorten the polarity switching time of the DC high-voltage generator and realize fast polarity switching, it is necessary to shorten the time of each process.

DC Hipot Tester.png

Three methods of fast polarity conversion method of DC high voltage generator:

1. Accelerating the step-down speed during the step-down process is one aspect of shortening the polarity switching, mainly by increasing the discharge resistance to speed up the step-down speed. Increasing the discharge resistance does not increase the total resistance of the discharge resistance, but increases and divides the voltage. The number of resistors connected in parallel with the same resistance value. The larger the number of bars, the smaller the total resistance and the faster the voltage drop. At the same time, the lower limit of the discharge resistance should be considered, because too small discharge resistance will inevitably lead to the normal operation of the device When the leakage current increases.

2. In the grounding process of the grounding switch, it takes a long time for the test voltage to be grounded to zero or zero. When the DC high voltage generator voltage drops from the test value to a certain level, the direct grounding of the fast grounding switch can greatly shorten the grounding process of the grounding switch. However, the fast grounding switch that meets the high voltage requirements can withstand all high voltages and large currents. The grounding switch is extremely demanding.

3. Simply put, the silicon stack needs to realize fast polarity switching to realize the polarity switching of the internal single tube. In order to achieve this goal, we must first consider motivation. At present, there are three simple powers, driven by electric, pneumatic and hydraulic methods. According to the structural characteristics of the DC high-voltage generator, it is impossible to achieve power supply under high pressure. The pneumatic device has the compression ratio of the air source used by the cylinder. If all the silicon reactors are connected in series through the gas pipe, when the humidity in the gas is high, the entire equipment will be discharged from the gas pipe, causing equipment damage, etc. The use of vacuum-treated alkylbenzene insulating oil in the hydraulic method will not cause emissions. Secondly, the compression ratio of oil is much smaller than that of gas, which can realize the smooth polarity conversion of the silicon reactor and avoid the problems of the other two methods. In contrast, it can be seen that the hydraulic selection method is reasonable.

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