Modeling and stability analysis of grid-forming energy storage converter connected to AC power grid

doi:10.19799/j.cnki.2095-4239.2025.0191

Abstract

Abstract:

To meet the practical demand for safe and stable operation of new power systems, it is important to study the control strategy and stability mechanism of grid-forming (GFM) energy storage converters. This study establishes a small-signal impedance model of a GFM energy storage system connected to an AC power grid based on droop control. The impedance model expression in complex vector form is used to simplify the modeling process, and the dynamic characteristics of the active power loop are analyzed. The impedance model is verified through frequency sweep and time-domain simulations. Subsequently, the small-signal stability of the GFM energy storage system connected to the grid is analyzed using the generalized Nyquist criterion, with theoretical results consistent with time-domain simulation analysis. The results indicate that as the active power droop coefficient and short-circuit ratio increase, system stability deteriorates. This finding is further validated on a physical experimental platform.

Key words: grid-forming energy storage converter, impedance model, stability analysis, generalized Nyquist criterion

CLC Number:

TM 727

Zijun BIN, Xiangping KONG, Yunhui HUANG, Jixiang WANG, Beibei QI, Hao JIANG. Modeling and stability analysis of grid-forming energy storage converter connected to AC power grid[J]. Energy Storage Science and Technology, 2025, 14(9): 3434-3443.

Figures/Tables 14

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Table 1

Parameters of time domain simulation analysis"

参数	数值
功率基准值 $S b$	10000 kVA
电压基准值 $U b$	$(220 × 3) V$
电流基准值 $I b$	$(S b / 220 / 3) A$
角频率基准值 $ω 0$	$(2 π × 50) r a d / s$
滤波电感 $L f$	0.0649 p.u.
滤波电阻 $r f$	0.0069 p.u.
滤波电容 $C f$	0.0912 p.u.
网侧线路电感 $L g$	0.0865 p.u.
网侧线路电阻 $r g$	0.0138 p.u.
电流控制器比例系数 $k p i$	100
电流控制器积分系数 $k i i$	667
电压控制器比例系数 $k p v$	0.08
电压控制器积分系数 $k i v$	1
有功下垂系数m	$0.02 ω 0 / S b$
无功下垂系数n	$0.1 × 311 / S b$

Table 1

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Table 2

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参数	数值
额定有功功率P_e	5 kW
交流母线电压U_g	380 V
直流电容器C_dc	3 mF
直流母线电压U_dc	650 V
交流电感L_f	3 mH
模拟线路电感L_g	6 mH
采样频率	10 k