How to protect against lightning in substations?
According to the characteristics of substations, the principle of lightning protection has three aspects:
First: Directly lead most of the lightning current into the ground to disperse, which is an external protection against lightning attack. Lightning rods or lightning belts and grounding systems can be used as external lightning protection systems.
Second: Block the overvoltage and lightning current introduced along the power line or communication line, using internal protection and overvoltage protection.
Third: Limit the surge overvoltage amplitude on the protected equipment (overvoltage protection).
2. Specific measures for lightning protection in substations
The lightning strikes suffered by substations are descending lightning. The main lightning strikes directly on the electrical equipment of the substation, or the lightning waves formed by overhead lines and induced lightning overvoltage and lightning overvoltage invade the substation along the line, which is the key to lightning protection.
(1) Installation of lightning rods in substations
Install lightning rods on the substation to prevent direct lightning strikes. The lightning rod is a lightning receiver that protects electrical equipment and buildings from direct lightning strikes. Its function is to attract lightning to the lightning rod and safely introduce the lightning current into the ground, thereby protecting the equipment. When installing lightning rods in substations, all equipment should be within the protection range of lightning rods. In addition, measures should be taken to prevent counterattacks when lightning rods are struck by lightning. For 35KV substations, to protect the safety of outdoor equipment and structures, independent lightning rods must be installed. Ensure that the high potential generated by the lightning rod will not cause a counterattack accident of electrical equipment.
(2) Protection of transformer
The basic protection measure of the transformer is to install a lightning arrester close to the transformer, which can prevent the lightning wave invading the line from damaging the insulation.
When installing the lightning arrester, try to be as close as possible to the transformer, and minimize the length of the connection, so as to reduce the voltage drop of the lightning current on the connection line. At the same time, the wiring of the arrester should be connected with the metal shell of the transformer and the neutral point of the low-voltage side, so as to effectively reduce the chance of lightning damage to the transformer.
(3) Lightning protection grounding of substation
After the lightning protection of the substation meets the requirements, a unified grounding network must be laid according to the requirements of safety and work grounding, and then a grounding body shall be added under the lightning rod and arrester to meet the requirements of lightning protection, or a separate grounding body shall be laid under the lightning protection device .
(4) Lightning protection in substation
With the development of power technology, substations have a complete lightning protection system. Outdoor equipment is unlikely to be directly damaged by lightning, but the lightning discharge and electromagnetic pulse generated by the lightning protection system, as well as the lightning overvoltage, pass through the metal pipe cable Severe electromagnetic interference is caused to various weak current equipment such as substation control, which may affect the normal operation of substation equipment.