Photovoltaic power generation, according to the principle of photovoltaic voltaic effect, uses solar cells to directly convert sunlight into electrical energy. It is safe, reliable, noise-free, low-pollution, and free from geographical distribution. It can generate electricity on site without fuel consumption and erection of transmission lines and construction period. The short feature is one of the most popular clean new energy sources.
Photovoltaic power generation system is mainly composed of three parts: solar panel (component), charge and discharge controller and inverter. Depending on the system form, the following devices may be used to form the system: combiner box, AC power distribution cabinet, metering system, communication system, solar tracking system and other equipment.
Compared with wind power generation systems, the installation of photovoltaic equipment does not significantly increase the risk of direct lightning strikes, and the protection requirements for direct lightning strikes are relatively low. If a special lightning device is not used, the metal frame of the panel can be directly grounded and equipotentially connected to the entire system. At this time, the metal frame and the wire connecting the metal frame are required to be increased in cross section to withstand lightning current.
Whether it is a photovoltaic power plant or a distributed photovoltaic power generation system, the system equipment is always exposed to the outdoors, a large number of cables increase the possibility of being damaged by lightning electromagnetic pulses, and the electronic components of the inverter and other devices are very sensitive, to ensure its The service life of the design is essential for the protection of lightning electromagnetic pulses.
For the protection of lightning electromagnetic pulses, reasonable wiring, shielding measures should be taken, and the surge protector (SPD) should be used correctly.
In the photovoltaic system, there are both photovoltaic DC power supply and AC power supply. Both have different requirements for SPD. The main differences are as follows:
1. If the SPD is overloaded and short-circuited, the internal trip protection device will be disconnected and an arc will be generated during the disconnection. The AC power supply will automatically extinguish due to the voltage zero-crossing point, and the DC power supply voltage will not be zero, and the generated arc will not be automatically extinguished, which may cause the SPD to catch fire.
2. The photovoltaic system is similar to a current source whose short-circuit current is approximately equal to the rated current during operation. The AC power supply is equivalent to a voltage source, and the output current is large when short-circuited. Therefore, the choice of backup protection equipment is also different (SPD backup protection equipment usually uses a fuse, the purpose is to disconnect its SPD from the circuit when the SPD is short-circuited, to avoid fire).