An Identification Method for DC-Link Capacitor Capacitance of Grid Connected Inverter

doi:10.16183/j.cnki.jsjtu.2021.515

Abstract

Abstract:

DC-link for the capacitor is one of the most vulnerable components of the grid connected converter, whose capacitance identification will help to improve the system reliability by finding and replacing the aging capacitor in time. An identification method for the DC-link capacitor capacitance of the grid connected inverter based on pre-charging circuit is proposed. By analyzing the relationship between the capacitance and the charging current, charging voltage during pre-charging process, and combining the historical operating data, the set of capacitance state feature vector is built. The support vector regression (SVR) model is trained and the regression prediction relationship between the state value and the capacitance is set. The model is optimized by using the particle swarm optimization (PSO) algorithm, which can be used for capacitance identification of the DC-link capacitor. Simulation and experiments results show that the proposed method can implement the accurate capacitance identification of the DC-link capacitor of the grid connected inverter, with an identification error of less than 0.95%. This method does not need to add hardware circuit and change the control algorithm, and has a certain practical value.

Key words: grid connected inverter, DC-link capacitor, capacitance identification, pre-charging circuit, support vector regression (SVR)

CLC Number:

TM461.5

ZHU Chenghao, WANG Han, SUN Guoqi, WEI Xiaobin, WANG Fuwen, CAI Xu. An Identification Method for DC-Link Capacitor Capacitance of Grid Connected Inverter[J]. Journal of Shanghai Jiao Tong University, 2022, 56(6): 693-700.

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信噪比/dB	数据集类型	MSE	R'	MAPE
20	训练	7.2278×10^-6	0.9948	0.1761
	待测	5.1128×10^-7	0.9989	0.0444
15	训练	7.4148×10^-6	0.9945	0.1760
	待测	8.3376×10^-7	0.9982	0.0584
10	训练	7.4364×10^-6	0.9943	0.1754
	待测	1.0387×10^-6	0.9978	0.0654

实验组号	C/mF
1	1.15040
2	1.19154
3	1.23243
4	1.27497
5	1.31783
6	1.36036
7	1.40328

测试组号	电容真实值/mF	电容预测值/mF	误差/%
1	1.15040	1.1196	0.938
2	1.19154	1.2029	0.950
3	1.23243	1.2399	0.609
4	1.27497	1.2629	0.950
5	1.31783	1.3056	0.927
6	1.36036	1.3650	0.340
7	1.40328	1.4117	0.601