Research on stability optimization of grid-forming energy storage converter based on virtual bus voltage control

doi:10.19799/j.cnki.2095-4239.2023.0818

Abstract

Abstract:

As the key equipment of high proportion of new energy connected to the power grid, the grid-forming energy storage converter has stability problems under strong power grid. Aiming at this problem, this paper proposes a stability optimization method of grid-forming energy storage converter based on virtual bus voltage control. Firstly, the state space small signal model of the grid-forming energy storage converter is established, and the characteristic root analysis method is used to obtain that the stability of the grid-forming energy storage converter becomes worse or even oscillates under the strong grid. Then, a stability optimization method based on virtual bus voltage control is proposed. By changing the position of the active power loop tracking the grid voltage phase, the grid impedance is equivalently improved, so as to improve the stability of the grid-forming energy storage converter system under the strong grid. Then, the eigenvalue change trend and stability improvement effect of the system before and after adding the virtual bus voltage control under different working conditions are analyzed. At the same time, the influence of the compensation coefficient k and the time constant t in the virtual bus voltage control parameters on the stability is also analyzed and the general parameter design range is given. Finally, the grid-forming model of the grid-forming energy storage converter is built in Matlab / Simulink for time-domain verification, and the hardware-in-the-loop experimental platform is further built for semi-physical verification. The verification results show that the stability of the grid-forming energy storage converter based on virtual bus voltage control is significantly improved under strong power grid

Key words: grid-following energy storage, small-signal stability, virtual bus voltage control, stability optimization

CLC Number:

TM 712

WenBo YAN, YunHui HUANG, Dong WANG, JinRui TANG, KeLiang ZHOU. Research on stability optimization of grid-forming energy storage converter based on virtual bus voltage control[J]. Energy Storage Science and Technology, doi: 10.19799/j.cnki.2095-4239.2023.0818.

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电网强度和输出功率	SCR=5,P=1.0p.u.	SCR=6,P=1.0p.u.	SCR=5,P=0.8p.u.	SCR=5,P=1.2p.u.
主导特征根	-0.35±25.04i	0.10±25.89i	-0.98±23.99i	0.14±25.81i
振荡频率	3.98	4.12	3.82	4.11
阻尼比	0.014	-0.004	0.041	-0.005

	参数	含义	数值
系统参数	S_b	变流器基准容量	0.1MW
	U_N	变流器基准电压	381V
	P_ref	变流器给定有功功率	0.1MW
	Q_ref	变流器给定无功功率	0Var
	U_dc	储能直流侧电压	700V
	U_t	并网电压	381V
	U_g	电网电压	381V
	L_c	滤波电感	3mH
	L_g	线路电感	1.1mH
控制参数	D_p	阻尼系数	1.5
	J	惯量系数	20
	K_q	无功控制系数	5
	k_p1，k_i1	电压环比例，积分增益	5，200
	k_p2，k_i2	电流环比例，积分增益	0.3，0.05

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