Due to investment restrictions, the scale of photovoltaic power stations built in remote and powerless areas in China has not yet been completed to meet local electricity demand. In order to increase the power supply reliability of photovoltaic power stations, while reducing the battery capacity and reducing system costs, each power station is equipped with a backup diesel generator set as a backup power source.

The role of the backup power supply is:

First, when the battery is out of power and the solar battery array cannot be recharged in time, the backup diesel generator set can be used to charge the battery pack through the rectification charging device, and at the same time directly supply power to the load through the AC power distribution system to ensure the normal power supply system Run;

Second, when the inverter or other components fail, and the photovoltaic power generation system cannot supply power, as an emergency power source, a backup diesel generator set can be started to directly supply power to users through the AC power distribution system. Therefore, in addition to supplying the power output from the inverter to the load under normal circumstances, the AC power distribution system should also have the function of directly supplying the power output from the backup emergency power supply to the household under special circumstances.

It can be seen that there should be at least two power inputs for the AC power distribution system of independently operating photovoltaic power stations, one for the main channel transformer input and one for the backup diesel generator set input. In a photovoltaic power generation system equipped with a backup inverter, its AC power distribution system should also consider adding an input. In order to ensure the safety of the inverter and the diesel generator set, to prevent the danger that the inverter and the diesel generator set are powered at the same time, the two input power switching functions of the AC power distribution system must have absolutely reliable interlocking devices. As long as the inverter power supply operation steps are not completely ruled out, the diesel generator set cannot be powered. Similarly, when the diesel generator set supplies power to the load through the AC power distribution system, it must also ensure that the transformer is absolutely not connected to the AC power distribution system. .

The output of AC power distribution system can generally be designed according to user requirements. Generally, it is difficult to achieve 100% power supply guarantee for independent photovoltaic power stations. To ensure the power supply requirements of some special loads, the AC power distribution system should have at least two outputs. Load to ensure continued power to the main load. In some cases, the output of the AC power distribution system can also be three or four to meet different needs. For example, some places need long-distance power transmission and high-voltage power transmission and distribution should be carried out; some places need special power lines for government agencies, banks, telecommunications and other important units.