Analysis of Resonance Problem and Integrated Control Strategy for Dynamic Capacitor

Abstract

Abstract:

Power capacitor, was a basic element to supply static VAR in power system, which could be upgraded into dynamic capacitor using Buck-type AC-AC converter in this paper. By means of multiple synchronous reference frames and even harmonic modulation method, the simulation model of dynamic capacitor was built under Matlab/Simulink environment, and the VAR and harmonic integrated compensation functions of it were well proved. In the meanwhile, it was shown that either static or dynamic capacitor might cause harmonic resonance problem. The stability of the control loop of dynamic capacitor was corrupted for the existence of harmonic resonance when method of measuring grid current was used to control it. It could be improved by changing the polarity of resonant harmonic references, which was completely verified by preliminary simulation results.

Key words: Dynamic capacitor, even harmonic modulation, integrated compensation, harmonic resonance

CLC Number:

Dai Ziwei,Chen Xinwen,Wang Xin,Dai Ke. Analysis of Resonance Problem and Integrated Control Strategy for Dynamic Capacitor[J]. Journal of Electrical Engineering, 2015, 10(7): 33-40.

Figures/Tables 12

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References 11

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参数			数值
电源		电网电压V_s/V	380
		电网频率f/Hz	50
		电网等效电感L_s/μH	239
非线性负载		不控整流桥直流侧电感L/mH	80
		不控整流桥直流侧电阻R/Ω	24
		三相平衡感性负载电感L′/mH	9.6
		三相平衡感性负载电阻R′/Ω	1
D-CAP	硬件参数	无功补偿电容C/μF	900
		滤波电感L_F1/μH	12.5
		输入滤波电容C_F/μF	121
		输入滤波电感L_F2/μH	55.2
	控制参数	开关频率f_SW/kHz	16.5
		PI系数[k_{q1_P},k_{q1_I}]	[0,–1]
		PI系数[k_{d5_P},k_{q5_P},k_{d5_I},k_{q5_I}]	[0,0,0.3,–0.3]
		PI系数[k_{d7_P},k_{q7_P},k_{d7_I},k_{q7_I}]	[0,0,–0.1,–0.1]
		PI系数[k_{d11_P},k_{q11_P},k_{d11_I},k_{q11_I}]	[0,0,0.3,0.3]
		PI系数[k_{d13_P},k_{q13_P},k_{d13_I},k_{q13_I}]	[0,0,–0.1,–0.1]
		二阶LPF截止频率/Hz	50

谐波次数	无D-CAP		无功补偿			复合补偿			谐振抑制复合补偿
谐波次数	网侧电流幅值/A	PCC电压（%）	负载电流幅值/A	网侧电流幅值/A	PCC电压（%）	负载电流幅值/A	网侧电流幅值/A	PCC电压（%）	负载电流幅值/A	网侧电流幅值/A	PCC电压（%）
基波	69.64	100	70.04	54.69	100	68.34	55.31	100	69.61	54.73	100
5	4.60	0.54	4.64	6.45	0.75	2.93	0.16	0.22	4.72	0.00	0.00
7	3.16	0.52	3.17	8.06	1.32	2.23	0.30	0.24	3.33	0.00	0.00
11	2.00	0.52	2.13	1.94	0.50	4.47	117.53	30.35	2.12	0.00	0.00
13	1.65	0.50	1.77	0.58	0.18	2.70	39.70	11.83	1.79	0.00	0.00