Lightning protection solutions for large-scale grid-connected photovoltaic power stations

The influence of lightning on large-scale grid-connected photovoltaic power generation system:

The harm of lightning to large-scale grid-connected photovoltaic power generation system is mainly divided into two types: direct lightning and inductive lightning.

Direct lightning is a strong discharge between thunderclouds and ground equipment or lines, lightning flow through the object, will have a destructive effect of thermal and force effects, accompanied by electromagnetic effects and discharge on nearby objects. Most of the panels are installed on outdoor roofs or open places, so lightning is likely to directly hit the solar photovoltaic panels or brackets and transmission lines, causing damage to the equipment and even melting and burning.

Inductive lightning: lightning discharge will produce electrostatic effects and electromagnetic induction on nearby conductors, which can cause sparks between metal parts and cause fires when serious, which will damage electrical equipment such as solar panels and controllers or inverters, power distribution units, and AC loads.

Ground potential counterattack: In a solar power supply system with external lightning protection, lightning is introduced to the ground by the external lightning protection device. As a result, a high voltage is generated on the ground network and enters the device through the ground cable of the device. As a result, the controller, inverter, AC or DC load devices are damaged.

Design basis of lightning protection for large-scale centralized grid-connected photovoltaic power generation system:

The lightning protection of large-scale centralized grid-connected photovoltaic power generation system is different from that of general building electrical lightning protection, so it is necessary to design a reasonable and reliable lightning protection scheme according to the characteristics of large-scale centralized grid-connected photovoltaic power stations.

Lightning risk assessment for large-scale centralized grid-connected photovoltaic power stations: the assessment of lightning risk mainly follows the IEC 62305-2.

Lightning protection measures for large-scale centralized grid-connected photovoltaic power generation system:

1, Direct lightning protection:

For large-scale centralized grid-connected photovoltaic power generation systems, due to the large number of photovoltaic equipment concentrated in the outdoor exposure and occupy a large amount of outdoor space, it is extremely vulnerable to the threat of lightning when thunderstorms occur. In order to ensure that the solar panels exposed outdoors are not damaged by direct lightning strikes, it should be set up direct lightning protection devices, the specific measures are as follows:

A, Lightning arrester system

B, Down-conductor system

C, Grounded counterpoise

When installing and setting the lightning rod, should fully consider whether the protection range of the lightning rod can cover all photovoltaic equipment.

2, Inductive lightning protection:

Due to the inductive voltage caused by lightning discharge and the surge caused by lightning may damage the photovoltaic modules and inverters, and the electronic components in large-scale centralized grid-connected photovoltaic equipment are usually more sensitive, and the maintenance and repair costs of the equipment are high, so effective surge protection is essential. Reduce damage to equipment caused by surges and lightning overvoltage by installing surge protectors on live cables. The specific measures are as follows:

A, Surge protection:

Dc side (combiner box/DC panel): Surge protection devices are installed at each DC input end of the inverter.

Large distributed photovoltaic power generation system optional: BRITEC BRPV3-1000T1/BRPV3-1000 photovoltaic power supply lightning arrester.

Small distributed photovoltaic power generation system optional: BRITEC BR-40 24/BR-40 48 DC 24V/48V power surge arrester.

Ac side (AC panel): Install a surge protector in the control cabinet to prevent lightning waves from being invaded by the protective cable.

Single-phase Optional: BRITEC BR-40 2P 40KA single-phase power surge arrester.

Three-phase Optional: BRITEC BR-40 4P 40 kA three-phase power surge arrester.

B, Electromagnetic shielding:

Electromagnetic shielding of buildings, lines and equipment to the outside world prevents electromagnetic pulses and induction of high voltages. The shielding can be a sealed conductive shell, a coaxial jacket or a cable tube that passes through the cable or a high exposed protection wire is laid on the cable in the cable trench. The shell of the shielding device should be connected to the ground wire of the equipment.