Abstract：When multiple energy storage units are connected to an energy storage station by the power

electronic converter，the interaction and coupling effect bring challenges to the stable operation of the system. The

small-signal model of the parallel storage system was established. The stability analysis was carried out based on

the dominant modes and participating factors of the system. According to the relationship between DC bus voltage

and current，a new rule was found：when the load power was constant，the increase in the number of power stations will produce an impedance multiplier effect，which can improve the system stability margin. Moreover，the

improved participation factor method was proposed to verify the regularity of the effect. Finally，the experimental

results verify the correctness of the above analysis.

      Key words：energy storage power station；small-signal model；interactive coupling；stability analysis