Energy storage power station, as the super power banks of the power grid, play an increasingly important role in ensuring the stable operation of the power system. However, are you curious why there are voltage fluctuations in energy storage stations during charging and discharging? Under what circumstances can energy storage systems cause voltage instability?
The charging and discharging process of an energy storage power station is like charging and discharging a giant battery. This process is not static, but needs to be flexibly adjusted according to the needs of the power grid. Energy storage batteries can adjust parameters such as charging rate, discharging power, and charging and discharging time through battery management systems and energy storage inverters to adapt to different application scenarios. However, it is precisely this flexible adjustment that can cause voltage fluctuations.
So, what exactly causes voltage fluctuations during battery charging and discharging?
1. The influence of battery internal resistance: The chemical reactions and physical structure inside the energy storage battery determine its internal resistance during the charging and discharging process. The internal resistance will vary with the temperature, state of charge, charging and discharging current, and aging degree of the battery. When current passes through the battery, the internal resistance will cause a voltage drop, resulting in voltage fluctuations at both ends of the battery. When current passes through a battery, just like the resistance in a water pipe affects the water flow rate, the internal resistance changes with the current, causing voltage fluctuations at both ends of the battery.
2. Power variation: The power level of charging and discharging in energy storage stations can affect voltage fluctuations. When the charging and discharging power suddenly increases or decreases, the battery pack needs to respond quickly to this change, but there is inertia in the internal reactions and physical processes of the battery, which cannot immediately reach a new equilibrium state, resulting in voltage fluctuations.
3. Battery inconsistency: Energy storage stations are typically composed of multiple battery cells or modules, with performance differences such as capacity, internal resistance, open circuit voltage, etc. between these battery cells or modules. This inconsistency during the charging and discharging process can lead to asynchronous voltage changes in each battery cell or module, resulting in voltage fluctuations.
4. Grid interaction: The interaction between energy storage stations and the grid can also affect voltage fluctuations. When an energy storage power station discharges or charges from the grid, if the voltage stability of the grid is poor or there are other disturbance factors (such as load changes, switching of other power sources, etc.), the output or input voltage of the energy storage power station will also be affected, resulting in fluctuations.

Energy storage power stations may cause voltage instability in the following situations:

1. The impact of charging and discharging current: The charging and discharging current of energy storage power stations will vary according to the demand of the power grid. When energy storage power stations charge and discharge at high power, significant voltage fluctuations may occur due to the influence of battery internal resistance and power changes, which may lead to unstable system voltage.
2. Power grid impact: When there are disturbance factors in the power grid (such as voltage fluctuations, frequency changes, harmonic pollution, etc.), the energy storage system may be affected by these disturbances during its interaction with the power grid, resulting in unstable voltage. The energy storage power station is connected to the power grid, and the power grid itself also has impedance. When energy storage stations undergo large-scale charging and discharging, it will cause an impact on the impedance of the power grid, thereby affecting voltage stability.
3. Control system impact: causing unstable system voltage. The battery management system and energy storage inverter of energy storage power stations need to continuously adjust voltage and current parameters during the control of charging and discharging processes. If this adjustment process is too frequent or the parameters are set improperly, it has a significant impact on voltage stability. It may cause voltage fluctuations.
4. Battery aging: With the increase of battery usage time, its performance will gradually decline, such as capacity decay, internal resistance increase, etc. These changes may lead to greater voltage fluctuations during the charging and discharging process of the battery, thereby affecting the stability of the system voltage.
In order to minimize voltage fluctuations and ensure stable operation of the power grid, the following measures are essential:
1. Optimizing battery design: reducing battery internal resistance and improving battery charging and discharging efficiency are key to reducing voltage fluctuations.
2. Improved control strategy: Adopting advanced control algorithms and designing reasonable charging and discharging control strategies can effectively avoid the impact of high-power charging and discharging on system voltage stability.
3. Strengthening the support of the power grid: By strengthening the structure of the power grid, optimizing the parameters of the power grid, and other measures, the carrying capacity of the power grid and its interaction with the energy storage system can be improved, which can reduce the impact of energy storage power stations on the voltage of the power grid.
4. Regularly maintain and inspect the energy storage system, and promptly replace aging battery cells or modules.
Voltage fluctuations in energy storage power stations are a complex problem that requires comprehensive consideration of various factors such as battery characteristics, control strategies, and grid factors. I believe that with the advancement of technology and the accumulation of application experience, the voltage control level of energy storage power stations will continue to improve, making greater contributions to building a cleaner, more efficient, and stable power system.