Test And Research On DC Partial Discharge Signal Of Electrical Equipment

As a major pillar industry of gross domestic economic development of China, power industry plays an extremely important role. High Voltage Direct Current Transmission can transfer heavy capacity to far distance, and it can be controlled flexibly. In recent years, the HVDC have developed rapidly in the power industry all over the world, and as well as the DC voltage electrical equipment. Along with the enlarging of the power network and the increasing of the voltage level, the security and stability of the power system would be higher. At the same time, the security on the running state of DC electrical equipment would be advanced, too.Many reasons can lead to the insulation failure of electrical equipment. The partial discharge is an important reason for leading to the insulation deterioration of electrical equipment. So the partial discharge occupies a very important position in insulation test.First of all, this paper begins with the partial discharge theory, such as the definition, the categories, the elements, the characteristic of the partial discharge. And then introduces the mechanism of the partial discharge at DC voltage, in order to give a comprehensive summary of it. Based on the AC partial discharge testing system, we seted up the testing system of partial discharge at DC voltage. We test the signal of the DC partial discharge by the way of HFCT. And three typical discharges models are choosed. They are corona discharge, internal discharge and suspending discharge. The tests are done at different DC voltage. Based on the analysis, the relationship between the partial discharge amplitude and its number and the relationship between the time interval of discharge and its number are selected as PD pattern to identify its type. Finally, based on partial discharge tests at DC voltage, the article analyses and compares the characteristic parameters of the different type of the DC voltage partial discharge. The statistical characteristic parameters, including skewness and kurtosis, are selected as the partial discharge characteristic parameters at DC voltage; they can be used to effectively identify the types of partial discharge at DC voltage.