When AC overvoltage occurs in inverter, there are three situations:
Situation 1.The distance between grid-connected and grid-connected is too far, which leads to voltage elevation.
If the distance between grid-connected inverters and grid-connected points is too far, the voltage difference at the AC terminal side of the inverters will increase. When the voltage range of grid-connected inverters exceeds the prescribed grid-connected voltage range, the inverters will show the overvoltage of the grid. In addition, the long, thin, winding or irregular material of the cable used to connect the inverters to the grid will lead to the increase of voltage difference at the AC end of the inverters, so the selection and rational layout of the cables are particularly important.
In view of this situation, the first step is to check whether the grid-connected distance is too long, and the best way is to select the near grid-connected scheme; the second step is to check the cable distribution and quality, and to select reasonable wiring mode and qualified AC cable.
Situation 2.Multiple inverters with one access point
Connecting multiple single-phase inverters to the same phase will easily lead to unbalanced grid voltage, and the grid voltage will rise, which will naturally lead to excessive grid-connected voltage.
This situation is relatively good to solve, we need to consider the project grid-connected capacity allocation to the three-phase grid, choose multi-point grid-connected.
Situation 3: The installed capacity of photovoltaic in the same area is too large
The installed capacity of photovoltaic is too large, and the load digestibility of power grid is insufficient. In this case, the power generated by the photovoltaic system can not be consumed nearby, nor can it realize the long-distance transmission point. Naturally, the grid voltage will continue to rise, and the inverter will show that the grid-connected voltage is too high.
The solution to this situation is:
1. Volume reduction of photovoltaic power plants
2. Transformer Capacity Increase
3. Preventive measures: Preliminary survey of power grids to assess the appropriate grid-connected capacity (the best method)
As the "key man" of the whole photovoltaic system, the quality of the inverters directly determines the quality of the system. It is also very important for the installation and maintenance of the photovoltaic system to master the tips to solve the faults of the inverters.
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