the killer of solar power plant-DC arc

What is a DC arc? Arc is a kind of gas discharge phenomenon, the instantaneous spark generated by the current passing through some insulating medium, such as air, this is the arc. Both direct current and alternating current produce arcs. Sometimes when we plug in the socket, we will see a fire, which is a kind of AC arc. In a DC system, such as that caused by a string of photovoltaic cells, this arc is called a DC arc. Relatively speaking, the DC system is easier to generate arc than the AC system, and once the arc is generated, it is more difficult to extinguish the arc.

In a photovoltaic power station, the photovoltaic panels emit direct current, which is converted into alternating current after passing through the photovoltaic inverter. In photovoltaic power plants, the voltage of photovoltaic cells is very high, ranging from a few hundred volts to a maximum of 1500V. In fact, a voltage of several tens of volts is enough to generate a DC arc, and the high temperature generated by the DC arc can reach 4200 degrees. As you know that the melting point of copper is 1083 degrees, what will happen if the molten copper drips onto many villas with wooden roofs? It's very likely to cause a fire. Some villa fires in Europe are caused by DC arcs in rooftop photovoltaic power plants. Therefore, the DC arc protection of photovoltaic power plants is very important.

Why does a photovoltaic power station generate a DC arc? The main reasons for the occurrence of DC arc are as follows: terminals, terminals and fuse connections are not pressed tightly, busbar bolts are not tightened, oxidation occurs at connections, wire insulation is reduced, equipment insulation problems, etc.

What are the hazards of DC arcs to photovoltaic power plants? We summed up some, there are three categories. The first is equipment damage, and the combiner box, DC cabinet, battery board components, connectors, junction boxes, etc. are burned. The second is power loss. Any failure will cause less or no power generation. The third is security risks. Fire will endanger personal and property safety.

What is the probability of an arc generated by a power station? Taking a 10MW power station as an example, there are about 80,000 junction box connectors and 4,000 terminals, plus the internal solder joints of the battery board, the DC cabinet, and the internal nodes of the inverter. All together, there are at least 84,000. If the failure probability is 1 in 10,000, there are 8.4, so , the probability of occurrence is very high.

Is there any way to avoid or detect these failure points in time? Yes. First of all, you must use regular and qualified products, not fake and shoddy products. The second is to minimize the number of nodes. Third, construction personnel must use professional tools, and must go to work after vocational training and passing the assessment. Fourth, after the power station is installed, it must be checked. Fifth, there must be corresponding detection tools, such as this DC arc detection sensor. Once they detect a DC arc, they will alarm and cut off the circuit to eliminate hidden dangers. Sixth, there must be an energy monitoring platform to monitor all operating data in real time. Once hidden dangers are found, personnel can be notified immediately to deal with them.