What is the impact of relay protection?
1, high-frequency interference
If the power system is operating slowly at the isolating switch, arc flashover will occur at the two contacts of the isolating switch during operation, resulting in over-voltage operation, high-frequency currents, and high-frequency currents flowing through the busbars. A strong electric field and magnetic field are generated around, thereby causing interference to the relevant secondary circuit and the secondary device. When the interference level exceeds the allowable interference level of the logic device of the device, abnormal operation of the relay protection device will be caused, thereby making the entire device. The work logic or exit logic is abnormal, which causes great damage to the stability of the system. High-frequency current flows through the earth capacitance device to the ground net, which will cause the ground potential to rise.
2, lightning strike
When a grounding component or lightning arrester of a substation is struck by lightning, the high-frequency current generated by the lightning strike will cause transients in the substation's ground network system because the substation grounding network is high impedance or the grounding line from the device to the grounding network is high impedance. The increase of the state potential may cause the protective relay to malfunction or damage the sensitive equipment and control circuit.
3, radiation interference
In the new era, tools such as telephones and mobile communications are often used around the power system. Then, strong radiation fields and corresponding magnetic fields will be generated around it. The changing magnetic field is coupled into the loop of a nearby weak electronic device. The circuit will induce high-frequency voltage, forming a false signal source, resulting in incorrect operation of the relay protection device.
4, DC power interference
When a ground fault occurs in the substation, a ground fault current flows in the substation ground network and in the ground. The ground resistance of the ground grid makes the ground potential of the substation after the earth fault exceed the ground potential. The magnitude of the potential is determined by Ground network resistance and the size of the ground current, according to the relevant regulations in China, the maximum value of up to 10V per kilo-amperes of electricity. For short-time power interruption caused by faults on the DC circuit or other reasons, the interference of the power supply to the power supply is mainly DC and recovery. Because of the influence of the anti-interference capacitance and distributed capacitance, the recovery of the DC may be extremely short or may be long at the DC voltage. The recovery process. The logic loop inside the electronic device will be distorted, causing a transient potential difference of the relay, and thus affecting the entire protection system.
5, electrostatic discharge interference
In a dry environment, workers may have high voltages on their clothes. They can carry the charge far away when they wear boots so they will be discharged when they touch the electronic device. The degree of discharge depends on the grounding condition of the equipment, and the environment is different. In severe cases, the electronic components will be burned and the relay protection system will be destroyed.
If you are disturbed by these several aspects, it will seriously affect the normal operation of the related SDY702 microcomputer relay protection tester . Therefore, in the power system, it is necessary to pay attention to relay protection devices affected by these aspects to ensure the normal operation of the instrument.
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