Analysis on the Causes of Power Transformer Relay Protection Failure
The relay protection device has four properties:
One is sensitivity, which refers to the ability to reflect faults with a sensitivity coefficient.
The second is reliability, which means that no action is taken.
The third is rapidity, which can be quickly resolved in the event of failures and abnormalities.
The fourth is selectivity, the fault is removed, the fault is carried out in the minimum interval, and the power supply is continuously supplied to the portion where the fault has not occurred.
Power transformer relay protection failure reason
According to the previous operating experience, it can be concluded that the faults of the power transformer are generally divided into two types, one is an internal fault and the other is an external fault.
Internal faults are mainly faults occurring in the transformer, such as short-circuit occurrences between windings, grounding faults caused by lead wires or windings through the casing.
The external fault is caused by the failure of the lead wire outside the transformer tank and the insulating bushing. For example, the insulating bushing is broken and the grounding is short-circuited, because the lead wire is broken and the winding is deformed.
Transformer internal faults can be classified into electrical faults and thermal faults according to their properties.
Thermal faults are usually manifested by elevated temperatures or localized overheating in the transformer. Under normal circumstances, thermal faults generally have four fault conditions. When the temperature is less than one hundred and fifty degrees Celsius, it is mildly overheated; when the temperature is between 150 and 300 degrees Celsius, it is low temperature overheating; when the temperature is in three At 100 to 700 degrees Celsius, it is overheated at medium temperature; when the temperature is higher than 700 degrees Celsius, it is overheated at high temperature.
Electrical faults mainly refer to the deterioration or degradation of insulation performance inside the transformer due to high electric field strength. Electrical faults are classified into spark discharge, partial discharge, and high-energy arc discharge according to different discharge energy densities.
The latest development of relay protection technology: With the continuous improvement of the level of equipment manufacturing, the State Grid Corporation has organized a technical research on a new generation of protection devices featuring localization, miniaturization, and plug-and-play. Relay protection will Enter a new stage of development. In order to fully verify the performance of the first batch of localized plug-and-play protection devices, the National Research Center organized the Chinese Academy of Electric Power to carry out rigorous testing. After comprehensive and rigorous test verification, the tested equipment will be tested in the cold, high altitude, high temperature, high humidity, strong sunshine, salt spray and other representative areas.
When the power system malfunctions or fails, the faulty equipment can be removed from the system in the shortest time and in the smallest area, or the power system can be signaled to allow the on-duty personnel to repair the fault of the power system. Ensure that users can use electricity regularly, reducing the impact on people's lives and work.
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