Common Faults in Lightning Protection Grounding of Photovoltaic Power Plants

A power generation system that uses photovoltaic arrays to directly convert solar radiation into electrical energy is collectively referred to as a solar photovoltaic power plants.

The main common faults are as below.

The lightning arrester is damp

The main cause of moisture absorption in lightning arresters is poor sealing or the introduction of moisture during the assembly process. Under the influence of operating voltage and ambient temperature, the moisture inside the valve plate evaporates on the outer side of the valve plate and the inner wall of the ceramic sleeve, causing surface flashover.

Uneven voltage distribution and aging of resistance plates in zinc oxide lightning arresters

Some manufacturers may use voltage equalization capacitors and rings to evenly distribute the overall potential, but due to the lack of correct calculations and verification in the design, it is still possible for some valve plates of the lightning arrester to age and be taken out of operation due to uneven potential distribution.

Explosion during operation of lightning arrester

When the line is struck by lightning, the lightning arrester operates normally. Due to the poor arc extinguishing performance of the spark gap itself, when the gap cannot withstand the recovery voltage and breaks down, the arc will reignite, and the power frequency continuous current will reappear. The reignition valve plate will burn out the resistor, causing the lightning arrester to explode; or due to the unqualified anode of the lightning arrester valve plate, although the residual voltage decreases, the continuous current increases, and the gap cannot extinguish the arc, causing an explosion.

Fuse-blown in Potential Transformer

False grounding signal

When charging the no-load busbar with a transformer, the three-phase switches are closed at different periods, resulting in unbalanced three-phase to ground capacitance and displacement of the neutral point. Asymmetric three-phase voltage can also be reported as grounded. This situation only occurs during operation. As long as the busbar and distribution equipment are checked and there are no abnormalities, it can be determined that it is a false grounding signal.

Line grounding fault

Grounding of power lines is a common abnormal operating state in the power grid. Equipment such as towers, crossarms, insulators, and lightning arresters along the line, as well as tree branches and small objects falling on both sides of the line, can easily cause system grounding, especially in strong winds and thunderstorms, where grounding phenomena occur frequently. When one phase of the line is disconnected and grounded, although it causes three-phase voltage imbalance, the voltage value does not change after grounding.