Substation lightning protection measures - Solutions - Huaqiang Electronic Network

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Lightning protection measures are generally summarized as two 1) Avoid the entry of lightning waves; (2) Use lightning protection devices to introduce lightning waves into the grounding grid. Lightning protection measures should be installed according to the common lightning strike form, frequency, strength and the importance and characteristics of the protected facilities.
(1) Lightning strikes for lightning rods or lightning protection lines can only be changed by intercepting and guiding measures. The lightning receptor has a lightning rod and a lightning protection line. Most of the small substations use independent lightning rods. Most of the large substations use lightning rods or lightning protection lines on the substation structure, or a combination of the two, which has strict requirements on the drain line and grounding device. In view of the weather characteristics of lightning strikes, typhoons and heavy rains, timely update and installation of line arresters and lightning protection lines have been adopted; the lightning protection level of distribution lines has been improved; the grounding grid has been regularly tested to ensure that the grounding resistance of the grounding grid is qualified; Reinforcement to ensure that measures such as not falling down during typhoon.
(2) Arrest arrester on the low-voltage side of the transformer can reduce the lightning wave entering the substation to within the allowable value of the insulation strength of the electrical device. A lightning arrester is required on the low voltage (400V) side of the substation to limit the overvoltage during lightning wave intrusion. In order to ensure the safe operation of electrical equipment, when installing the lightning arrester, it is necessary to limit the residual voltage of the arrester and limit the steepness of the intrusion wave to a certain value. In China, metal oxide surge arresters (MOA) are mainly used. In addition to MOA, Western countries also install air gaps on all electrical devices as backup protection after MOA failure.
(III) Surge protector installed at the inlet end of the power supply Because the lightning wave has the characteristics of high peak value and high energy, a surge protector should be installed at the power incoming line to protect the entire device. After the lightning wave passes through the surge protector, the signal still contains some high-frequency components and higher energy, which poses a hazard to the power system. Therefore, the LC low-pass filter can be used for filtering and varistor (MOV) can be applied to the lightning energy. absorb. The MOV has good nonlinearity and can clamp the voltage to a safe range.
(4) The grounding device has a good grounding device to guide the lightning current and prevent the dangerous potential from rising. Lightning protection grounding is applied to transmission, distribution network and substation of various voltage levels, which is an important measure to ensure electrical equipment and personal safety.
Grounding resistance of various lightning protection groundings should meet the following requirements:
1. Independent lightning rod: The independent lightning rod refers to a lightning rod that is not connected to the main grounding net and is used as a grounding net. Rid ≤ 10 ohms.
2. Arrester: The grounding of each voltage level arrester is connected to the main grounding grid, and the grounding resistance value is not specified.