Research on Model Predictive Current Control Strategy for AC Electric Springs

doi:10.12096/j.2096-4528.pgt.24201

Abstract

Abstract:

Objectives To improve the ability of AC electric springs (ACES) to stabilize the voltage of critical load (CL) under load switching and grid-side voltage fluctuations, a model predictive current control (MPCC) strategy is proposed. Methods Firstly, for variable load conditions, the reference model of the critical load current is established as the ratio of the next critical load reference voltage to the critical load equivalent impedance at the current moment. The dynamic response capability of ACES during load switching is improved by using the variable critical load current reference value. Secondly, to address critical load voltage fluctuations, the control strategy operates the ACES in different modes, enabling the predicted critical load current to track the varying current reference value. This further ensures that the critical load voltage tracks the given value. Results Under the conditions of load switching and grid-side voltage fluctuations, the proposed control strategy suppresses the critical load voltage fluctuations within 0.45% while maintaining the power quality of the non-critical load, and controls the total harmonic distortion of the critical load voltage below 0.6%. Conclusions The control strategy effectively improves the ability of ACES to suppress load voltage fluctuations and provides a reference for its integration into the power grid.

Key words: current control, model predictive control, AC electric spring, critical load

CLC Number:

TK 01

Weihan FAN, Qingfang TENG, Zhiwen JIANG, Zhijie ZHENG, Qing ZHONG, Xiping MA. Research on Model Predictive Current Control Strategy for AC Electric Springs[J]. Power Generation Technology, 2025, 46(5): 968-976.

Figures/Tables 19

Fig. 1 Individual ACES and its typical application topology

Tab. 1 Physical quantities and units

物理量	单位
初始网侧电源 $V ˙ G$	V
传输线路电阻R_L	Ω
传输线路电感L_L	mH
非关键性负载Z_{NCL_}_n	Ω
关键性负载Z_{CL_}_n	Ω
ACES直流侧电压V_DC	V
ACES滤波电感L_f	mH
ACES滤波电容C_f	mF
传输线电流 $I ˙ Z L$	A
非关键性负载电流 $I ˙ N C L$	A
关键性负载电流 $I ˙ C L$	A
半桥逆变电路电容 $C 1$ 、 $C 2$	F
逆变电路交流侧输出电压 $V ˙ i n$	V
逆变电路交流侧输出电流 $I ˙ L f$	A
ACES输出电压 $V ˙ E S$	V
非关键性负载电压 $V ˙ N C L$	V
关键性负载电压 $V ˙ C L$	V

Tab. 1 Physical quantities and units

物理量	单位
初始网侧电源 $V ˙ G$	V
传输线路电阻R_L	Ω
传输线路电感L_L	mH
非关键性负载Z_{NCL_}_n	Ω
关键性负载Z_{CL_}_n	Ω
ACES直流侧电压V_DC	V
ACES滤波电感L_f	mH
ACES滤波电容C_f	mF
传输线电流 $I ˙ Z L$	A
非关键性负载电流 $I ˙ N C L$	A
关键性负载电流 $I ˙ C L$	A
半桥逆变电路电容 $C 1$ 、 $C 2$	F
逆变电路交流侧输出电压 $V ˙ i n$	V
逆变电路交流侧输出电流 $I ˙ L f$	A
ACES输出电压 $V ˙ E S$	V
非关键性负载电压 $V ˙ N C L$	V
关键性负载电压 $V ˙ C L$	V

Fig. 2 ACES working vectors

Fig. 3 Structure of V˙CL_ref generation

Fig. 4 Working process of MPCC

Fig. 5 PI control block diagram of ACES

Tab. 2 Simulation parameters

参数	数值
初始网侧电源 $V ˙ G$ /V	313
传输线路电阻R_L/Ω	0.1
传输线路电感L_L/mH	1.22
非关键性负载 $Z N C L 1 / Ω$	30+j10
非关键性负载 $Z N C L 2 / Ω$	30+j10
关键性负载 $Z C L 1 / Ω$	50+j10
关键性负载 $Z C L 2 / Ω$	50+j10
ACES直流侧电压V_DC/V	400
ACES滤波电感L_f/mH	4
ACES滤波电容C_f/mF	0.75
采样周期T_S/s	10^-4
参考电压有效值V_{CL_refRMS}/V	220

Tab. 2 Simulation parameters

参数	数值
初始网侧电源 $V ˙ G$ /V	313
传输线路电阻R_L/Ω	0.1
传输线路电感L_L/mH	1.22
非关键性负载 $Z N C L 1 / Ω$	30+j10
非关键性负载 $Z N C L 2 / Ω$	30+j10
关键性负载 $Z C L 1 / Ω$	50+j10
关键性负载 $Z C L 2 / Ω$	50+j10
ACES直流侧电压V_DC/V	400
ACES滤波电感L_f/mH	4
ACES滤波电容C_f/mF	0.75
采样周期T_S/s	10^-4
参考电压有效值V_{CL_refRMS}/V	220

Fig. 6 RMS of critical load voltage under condition 1

Fig. 7 Critical load current under condition 1

Fig. 8 RMS of non-critical load voltage under condition 1

Fig. 9 Total harmonic distortion of critical load voltage under MPCC control in condition 1

Fig. 10 Total harmonic distortion of critical load voltage under PI control in condition 1

Fig. 11 Reactive power of ACES in condition 1

Fig. 12 RMS of critical load voltage under condition 2

Fig. 13 Critical load current under condition 2

Fig. 14 RMS of non-critical load voltage under condition 2

Fig. 15 Total harmonic distortion of critical load voltage under MPCC control in condition 2

Fig. 16 Total harmonic distortion of critical load voltage under PI control in condition 2

Fig. 17 Reactive power of ACES in condition 2

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