Research on Grounding System of High Voltage Winding

In recent years, China’s research in governors has continued to progress and develop. After the development of some companies, after the company can use the servo motor or AC motor instead of electro-hydraulic converters, it seems that there are momentum to shake off the electro-hydraulic converter. However, many foreign companies are still using electro-hydraulic converters as governor conversion components. For example, French companies have used electro-hydraulic converters for the governor units used in China's Three Gorges power station for hydro-generator units. The development process is that as the voltage on the inductor rises, it gradually enters the saturation region and gradually decreases; when the saturation value is close to the value, the system generates an overvoltage to the ground. At this time, the three-phase line voltage remains symmetrical and has normal The value, plus the operating voltage, is the relative ground voltage. This overvoltage can cause the breakdown of the system where the insulation is relatively weak, resulting in a short circuit between phases, damage to electrical equipment, and severe damage to the main transformer.

It can be seen that a small voltage transformer winding grounding can seriously damage the entire system, and the consequences are very serious. Neutral non-directly grounded power grid should prevent ferromagnetic resonance over-voltage generated under the following conditions; distribution transformer high-voltage winding short circuit to ground. Distributed in different users and different operating environments, the maintenance workload is large, so there are more opportunities for failure. In order to reduce malfunctions, it is necessary to strengthen operation and maintenance and technical management. The main measures include: improving the equipment data management, establishing the equipment account for each distribution transformer, strengthening the supervision of insulation, and supervising the oil affairs, and proceeding in accordance with the “Preventive Test Regulations for Electrical Equipment” All tests make the equipment run in good condition for a long time.