Why does lightning damage the inverter? How to prevent it?

Publisher:CrystalDawnLatest update time:2014-03-22 Source: 21世纪电源网Keywords:Lightning Reading articles on mobile phones Scan QR code
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To operate the megawatt (MW) photovoltaic power generation business stably and improve profitability, power generation operators must have knowledge of electrical equipment and build and operate appropriate photovoltaic power generation systems. Takuo Itami, a technician at Toshiba Mitsubishi Electric Industrial Systems (TMEIC), Japan's largest MW-class photovoltaic inverter (PCS) manufacturer and consultant to the "Million Photovoltaic Business Network", will answer some basic technical questions about photovoltaic power plants in this series.

First of all, there are two types of impacts caused by lightning on photovoltaic power stations, namely "direct lightning" and "induced lightning". As the name suggests, direct lightning refers to the photovoltaic power generation system being directly struck by lightning; induced lightning refers to the situation where lightning strikes nearby and the electrical energy generated by the lightning is transmitted through the transmission lines and grounding wires in the photovoltaic power generation system, applying a voltage far exceeding the rated level to the power generation equipment, thereby causing damage to the equipment.

Direct lightning strikes can be avoided by lowering the height of the photovoltaic system from the ground during design. Unlike windmills, MW-class photovoltaic power plants with low ground heights have rarely been struck by lightning, so it can be said that direct lightning strikes have little impact on them. However, photovoltaic power plants in mountainous areas may still be struck by lightning, and in this case, measures such as installing lightning rods or lightning conductors around the solar panels are needed.

In terms of induced lightning, lightning that strikes buildings or the ground near a photovoltaic power station will cause the potential of the grounded part of the power generation equipment (the voltage at a certain point compared to the reference point) to rise, and the induced potential will cause the main circuit in the power generation equipment such as PCS to generate a transient abnormally high voltage - surge voltage. This voltage will destroy the insulation part of the power generation equipment and cause damage to the equipment.

As a countermeasure, a lightning arrester (SPD) is generally installed in the junction box and PCS to deal with the intrusion of induced lightning surge voltage. The lightning arrester adopts a mechanism that causes a short circuit when a voltage above a certain level is applied to prevent damage to the power generation equipment. In addition, large-capacity capacitors that stabilize unstable solar energy are installed on the PCS, which also plays an important role in suppressing surge voltage.

PCS is equipped with overvoltage and overcurrent protection devices that disconnect the DC circuit to prevent accidents caused by lightning strikes, but it is important to repair the fault as soon as possible to minimize power generation losses. TMEIC saves the voltage and current waveforms 10μs before the protection device is activated in the memory card to grasp the intrusion surge energy and lock the faulty component in a short time, thereby shortening the repair time.

In the event of an accident such as a lightning strike, the voltage and current waveforms 10μs before the protection device is activated are saved in the memory card, and the faulty component is locked in a short time. In addition, when dealing with surge voltages on metal wires used to send monitoring signals, etc., measures can be taken to equip SPDs (surge protection devices).

In addition, communications for remote monitoring monitors generally use optical cables rather than metal cables that are easily affected by lightning strikes.

Keywords:Lightning Reference address:Why does lightning damage the inverter? How to prevent it?

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