Home > Knowledge > Content
How to solve PV inverter AC overvoltage problem?
- Jul 26, 2018 -

Nowadays, photovoltaic grid-connected power generation is becoming more and more popular, but many people are not familiar with PV grid-connected systems, especially grid-connected inverters. Even some technicians of installation companies can't make decisions about the common faults of inverters. Quickly check.

Therefore, when the inverter feeds back some system fault information, everyone will be helpless. Therefore, understanding the tips for solving inverter faults is an important condition to ensure the normal operation of the inverter.

PS6530B.jpg     grid-connected systems.jpg

In principle, the PV inverter itself does not generate voltage. The voltage displayed by the inverter comes from the PV module, called DC voltage, and the other part comes from the grid called AC voltage. What to do if “Grid-connected inverter shows AC overvoltage problem”.

According to the relevant regulations, the PV grid-connected inverter must work within the specified grid voltage range, can be monitored in real time and synchronized with the grid voltage. When the inverter detects that the grid voltage (AC voltage) is outside the specified range, the inverter The device must be tripped to stop working in order to ensure the safety of the equipment and protect the personal safety of the operator.

When the inverter has AC overvoltage, it may be caused by the following three conditions:

Case 1: The grid connection distance is too far, resulting in an increase in voltage

If the grid-connected inverter is too far away from the grid connection point, the voltage difference on the AC terminal side of the inverter will increase. When the inverter is connected to the grid-connected voltage range, the inverter will display the grid overvoltage. In addition, the cable used by the inverter to the grid point is too long, too thin, entangled or the material is not in compliance, which will lead to an increase in the voltage difference at the AC terminal of the inverter. Therefore, cable selection and rational layout are used. very important.

In this case, first check whether the grid connection distance is too long, it is best to choose the nearest grid connection scheme; secondly check the cable distribution and cable quality, select the reasonable wiring method and qualified AC cable.

Case 2: Multiple inverters focus on one access point

The actual rise of photovoltaic power generation is not long. The power supply bureau has not experienced much when selecting inverters for grid connection, and sometimes it seems unprofessional. It is often the case that multiple single-phase inverters are connected to the same phase, which can easily lead to grid voltage imbalance, and the grid voltage rises, which naturally causes the grid-connected voltage to be too high.

This situation is relatively better to solve, you need to consider the project grid-connected capacity to the three-phase grid, choose multi-point grid.

Case 3: PV installation capacity in the same area is too large

With the development of the photovoltaic market, the government has subsidized photovoltaic power generation. More and more households have installed photovoltaic power generation systems. As a result, there may be too many photovoltaic installed capacity in the power supply range or area of the same transformer. The load digestibility is insufficient. Since the electric energy generated by the photovoltaic system cannot be consumed nearby, and the long-distance transportation cannot be realized, the natural grid voltage will continuously rise, and the inverter will show that the grid-connected voltage is too high.

The solution to this situation is:

1. The photovoltaic power station reduces the installed capacity of photovoltaics;

2. The transformer increases the installed capacity of the photovoltaic;

3. Do a good job of precaution: survey the power grid in the early stage and evaluate the appropriate installed capacity of the grid.