Dynamic allocation method of DC side power based on the SoC of battery for STATCOM/BESS

• We establish an overall small-signal model of STATCOM/BESS system.
• We build a unified control strategy for STATCOM/BESS system.
• We build a balance control strategy for multiple energy storage modules at the DC side based on variable proportion coefficient control.
• A faster method to keep the SOC value of all energy storage modules at the same level.

With the integration of battery energy storage system to static synchronous compensator (STATCOM), the power quality can be further improved by additional active power compensation capacitive. When multiple storage modules are paralleled to the DC side of STATCOM, in order to make full use of DC energy storage module, this paper proposes a fast power dynamic allocation method in DC side. This method is realized by using variable ratio control to allocate the active power between various energy storage modules, considering the state-of-charge (SoC) of various energy storage module and the SoC of average difference. Compared to the traditional proportional coefficient control methods, by utilizing the real-time change ratio, the balance of power among different modules can be fast achieved. An overall mathematical model of STATCOM and battery energy storage system (BESS) is established in this paper, and an overall control method for STATCOM/BESS is thereby implemented based on this model, coming up with the tuning method for the variable proportional coefficient. Finally, the simulation and experimental results verify the effectiveness of the proposed control method.

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