Photovoltaic Power Generation System Surge Protector Solution

Photovoltaic power generation is another renewable clean energy besides wind power generation, and is widely used in various countries and regions. It has the characteristics of simple installation, scalability, stability, and long life. Generally speaking, a photovoltaic power generation system consists of photovoltaic panels, junction boxes, inverters, distribution cabinets, batteries, and corresponding bus control systems. A large number of electrical and electronic equipment are integrated inside, and these devices are concentrated in a relatively small space. There is no doubt that lightning strikes and surges are also a major disaster for photovoltaic power generation systems.

According to the IEC 62305 series of standards and the special requirements of photovoltaic DC systems, the lightning protection zones of photovoltaic power generation systems and the installation and selection of photovoltaic surge protectors must be considered:

1. Lightning protection zone (LPZ 0…3);

2. Test current waveform that SPD complies with (8/20 waveform and waveform, etc.);

3. Voltage protection level (especially the UP value of SPD on the AC side);

4. Open circuit voltage on the DC side;

5. Harmonic interference, etc.

Based on standards

1. EN 50539-11 "Surge Protectors for Photovoltaic Systems"

4. IEC 62305 "Lightning Protection" series of standards

5. IEC 61312 "Protection against Lightning Electromagnetic Pulses"

6. IEC 61643-11 "Surge Protectors Connected to Low Voltage Distribution Systems"

7. GB 50057 "Lightning Protection Design Specifications for Buildings"

Key points for selecting photovoltaic system protection:

Breakdown: To prevent breakdown, the flow rate is the key parameter of SPD

Trip: Timely tripping when surge protective device fails will avoid combustion accidents. How to ensure accurate and timely tripping is an issue that must be considered when designing SPD

Arc: After surge protection device trips, it will produce arcing (arc). In photovoltaic DC systems, the frequency of voltage and current is constant and not at the zero point of the phase. Therefore, compared with SPDs in AC systems, the arc generated by SPDs in DC systems when tripping is not easy to extinguish by itself, which can easily cause SPD combustion. This is not allowed for both the SPD itself and the protected system

Harmonics: Factors such as AC/DC inverters and nonlinear loads will cause harmonics, which will cause the voltage to rise to more than kilovolts for a long time. How to ensure that the SPD itself is not damaged is a key issue