Research on Control Strategy of Independent Micro-grid with Photovoltaic Energy Storage

doi:10.11930/j.issn.1004-9649.202404075

Abstract

Abstract:

Regarding the volatility and uncertainties in the operation of independent microgrid with photovoltaic energy storage, a control strategy based on sliding mode is proposed to enhance the robustness against various disturbances and improve the system dynamic performance. In order to effectively reduce the adverse effect of external solar irradiation, a non-singular fast terminal sliding mode control (NFTSMC) based on front DC/DC converter is proposed, in which incremental conductance method (InC) is implemented , to boost the maximum power point tracking (MPPT) performance by means of adjusting the photovoltaic output voltage tracking reference voltage. In order to alleviate the adverse effect of load change on the system performance, a control scheme based on sliding mode control of full bridge inverter is proposed to achieve low steady state error and rapid dynamic response. Furthermore, in order to maintain the voltage stability of the DC bus, the traditional dual-circuit PI control scheme is used to realize the bidirectional DC/DC converter to ensure the power balance of the system. Finally, simulation tests are carried out in Matlab/simulink environment to verify the effectiveness of the control strategy.

Key words: independent optical storage microgrid, non-singular fast terminal sliding mode control, maximum power point tracking, PI control

CHEN Jiong, WU Wenqing, LI Hao, QIN Ziyi, CHEN Xiang, CHEN Xuanyuan. Research on Control Strategy of Independent Micro-grid with Photovoltaic Energy Storage[J]. Electric Power, 2025, 58(5): 74-81, 198.

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URL: https://www.electricpower.com.cn/EN/10.11930/j.issn.1004-9649.202404075

https://www.electricpower.com.cn/EN/Y2025/V58/I5/74

Figures/Tables 14

Fig.1 Structure of independent micro-grid system with photovoltaic and energy storage

Fig.2 DC/DC equivalent circuit

Fig.3 Equivalent circuit of inverter

Fig.4 Bi-directional DC/DC equivalent circuit

Fig.5 Schematic diagram of non-singular fast terminal sliding mode control

Fig.6 Inverter control schematic diagram

Fig.7 Dual-loop PI control schematic diagram

Table 1 System parameters

设备	参数	数值
DC/DC变换器	L/mH	0.352
DC/DC变换器	C_in/mF	2.2
单相逆变器	L_f/mH	1.7
单相逆变器	C_f/μF	66
双向DC/DC变换器	L₁/mH	0.3
双向DC/DC变换器	C₁/μF	100
光伏电池	开路电压 U_oc/V	44.14
	短路电流 I_sc/A	5.43
	最大功率点电压 U_mp/V	36.72
	最大功率点电流 I_mp/A	5.03

Fig.8 Dynamic response to solar irradiation changes under 2 control schemes

Table 2 upv data analysis under the two control schemes

方案	波动幅值/V	响应时间/s	降幅/%	响应提升/%
1	1.33	0.0245	77.68	34.67
2	5.96	0.0375	77.68	34.67

Table 3 ipv data analysis under the two control schemes

方案	波动幅值/A	响应时间/s	降幅/%	响应提升/%
1	0.100	0.0165	70.15	54.17
2	0.335	0.0360	70.15	54.17

Table 4 ppv data analysis under the two control schemes

方案	波动幅值/W	响应时间/s	降幅/%	响应提升/%
1	3.115	0.0160	52.15	39.62
2	6.510	0.0265	52.15	39.62

Fig.9 Dynamic response of schemes 3 and 4 when load step change

Fig.10 System THD under the control schemes 3 and 4

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