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Basic requirements for substation lightning protection design
Overvoltage protection features and basic requirements: - Zhengzhou Yangbo Lightning Protection Technology Co., Ltd.
Variable voltage is the hub of the power system and it is responsible for the important task of power supply. Apart from possible direct lightning strikes, substations may also threaten the safety of substation equipment by lightning waves transmitted from the substation to the substation. Once a damage accident occurs, the consequences are very serious. To do this, we must do a good job of overvoltage protection at substations and block all loopholes to ensure uninterrupted power supply to our customers. (1) Characteristics of substation overvoltage protection: As the substation and the overhead line are directly connected, the insulation level of the line is often higher than that of the electrical equipment in the substation, especially the line of the wooden crossarm is more prominent, so along the The amplitude of the lightning wave from the intrusion of the line into the substation is often very high. Without proper protection facilities, the insulation of the main transformer or other electrical equipment in the substation may be damaged. If it is a terminal substation, after the wave reaches the substation, the amplitude will be doubled due to the reflection at the end, and the danger is even greater. (2) Basic requirements:
Knowing what you know is what you can do. In order to implement reliable lightning protection for substations, we must first understand the harm of lightning to substation equipment and the measures that can be taken to prevent lightning damage to substation electrical equipment.
There are two dangers of lightning: First, it can be as high as several or even several tens of megavolts; second, it can be as high as several hundred kiloamperes. In the normal operation of the power system, the insulation of the electrical equipment is below the rated voltage of the power grid. However, due to lightning strikes, faults, operation, or improper adjustment of system parameters, the voltage may increase, sometimes exceeding the normal values, causing breakdown of the equipment insulation, and seriously threatening the safe operation of electrical equipment. The voltage that jeopardizes the insulator is called overvoltage. Overvoltage due to fault, operation, or improper system parameter coordination is called internal overvoltage. The overvoltage caused by a lightning strike is called atmospheric overvoltage. Atmospheric over-voltage is caused by a lightning strike and is caused by a large lightning current flowing through the object. Inductive lightning over-voltage is caused by lightning strikes near the equipment due to the severe changes in electromagnetic waves. Direct lightning overvoltage is a serious hazard to the insulation of electrical equipment. Protective measures must be taken. The amplitude of induced lightning overvoltage generally does not exceed 500KV. In this case, insulation of 35KV and below is dangerous, and protective measures should be taken, and for 110KV At or above the level of insulation, the impact withstand voltage level is generally higher than this value, so there is no danger. Here we have designed a 110KV substation lightning protection, so we only discuss the atmospheric overvoltage caused by lightning strikes.
In substations, there are usually tall buildings. If a lightning strike strikes a major accident, it must be equipped with a perfect direct lightning protection device, such as a lightning rod or a lightning conductor. In order to save investment, it is necessary to make full use of the structure of substations, lighting lighthouses or installing lightning rods on tall buildings. The direct lightning protection scope of the substation shall also include the specific calculation of the direct lightning protection scope of the terminal tower and the substation. The protection scope map shall be drawn to prevent any blank spots from being protected, so that all the equipment that should be protected shall be protected. Within the direct lightning protection range. The incoming and outgoing lines of the substation should have perfect lightning protection devices. The 110 kV and above high-voltage power transmission lines are generally protected by lightning conductors on the entire line to prevent the lightning from entering the substation after the conductors are directly struck by lightning. . For 35KV lines, in order to reduce the line cost, generally only in the substation into the line