Daily maintenance and charge and discharge test of battery in photovoltaic power station

1. The role of the battery in the DC system

In the DC system of photovoltaic power plants, battery packs play an extremely important and indispensable role. Usually, the DC load of the power station is carried by the DC charging device, and the battery pack is float charged, and the battery pack is in a floating charge standby state. When the AC power is lost, the DC charging device is faulty or in an accident state, the battery pack starts to provide energy to all DC loads, such as relay protection devices and automatic device power, circuit breaker control and closing power, UPS device DC power, remote control and DC power supply for communication equipment and emergency lighting power supply, etc. Obviously, the battery pack is only a backup device in the power system at ordinary times, but in an accident state, the battery pack is the only supplier of DC loads. Once the battery fails, the power generation system of the photovoltaic power station will face paralysis or even a major accident, resulting in huge loss.

2. Types of batteries in photovoltaic power plants

The type of battery generally used in photovoltaic power stations is lead-acid battery. The capacity of the battery pack is generally 200Ah. There are two combinations of 12V monomer, 18 cells/group and 2V, 104 cells/group. The latter is generally used in photovoltaic power plants more extensive.

3. Routine maintenance content of battery

(1) Remove surface dust;

(2) Check whether there is looseness, heat and corrosion at the connection;

(3) Check the battery case for leakage and deformation;

(4) Check whether there is acid mist escaping around the pole and safety valve;

(5) Check whether the floating charge voltage of the battery pack is normal;

(6) Check whether the battery pack temperature is normal;

(7) Measure whether the floating charge voltage of the single battery is within the range of 2.25±0.03V;

(8) The battery pack is connected to a DC load of about 2000W, and under the condition of a discharge current of about 10A, check whether the voltage of the single battery is normal;

(9) For battery packs that have been in production for many years, if the internal resistance of individual batteries increases and performance declines, the solution is to maintain and activate, that is, to clean the plates, replace the electrolyte, and charge and discharge repeatedly with high current; it is not recommended to replace individual batteries. Several new batteries, otherwise the internal resistance of the new and old batteries will be different, which will lead to poor performance of the whole battery and greatly reduce the service life of the whole battery.