Study on Power Quality Control of Photovoltaic Power Generation Connected to Weak Power Grid

doi:10.11985/2023.02.023

Abstract

Abstract:

In order to meet the power quality requirements of large-scale PV connected to weak power grid system, a power quality control scheme with smooth switching, low consumption and resistance fundamental frequency is introduced to be suitable for the special application scenario. Through a specific project as an example, the high-frequency harmonic pollution and sufficient reactive power characteristics of photovoltaic power generation connected to the weak grid are explained. In order to meet the power quality requirements of photovoltaic grid-connected in this scenario, a special high-pass filter topology with fundamental resonance and smooth switching is designed. By deducing the frequency-resistance characteristic and resonance phenomenon of the high-pass filter, the superior suppression performance of the high-pass filter to high-order harmonics and the principle of not changing the reactive power flow distribution are revealed. At the same time, the smooth switching control and parameter setting method are given for the safe and stable operation of the equipment. Finally, the simulation model built in ETAP and the one-week grid-connected power quality test of the PV all prove the rationality and effectiveness of the proposed method.

Key words: Photovoltaic power station, high frequency harmonics, power quality, weak power grid

CLC Number:

TM72

LIU Yuhan, HE Xin, LUO Longfu. Study on Power Quality Control of Photovoltaic Power Generation Connected to Weak Power Grid[J]. Journal of Electrical Engineering, 2023, 18(2): 229-235.

Figures/Tables 14

References 20

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光伏器件	参数	数值
主升压变压器	容量/(MV·A)	40
	联结方式	YN/d11
	变比	63±10×1.5%/22 kV
	短路阻抗	10%
箱式升压变压器	容量/(MV·A)	2.2
	联结方式	D/yn11
	变比	22±2×2.5%/0.4 kV
	短路阻抗	6.5%
光伏逆变器	容量/(MV·A)	2.2
光伏逆变器	交流侧电压/V	385
60 kV电网	短路容量/MW	45
60 kV电网	X/R比	10
22 kV线缆	电阻/(Ω/km)	0.129
	电容/(Ω/km)	0.257
	电抗/(Ω/km)	0.109
	绝缘	AL/XLPE

运行方式	VTHD(%)	国际标准(%)
最大三相短路容量(56 MW)	5.03	3
最小三相短路容量(45 MW)	5.57	3

运行方式	VTHD(%)		抑制率(%)	国际标准(%)
运行方式	滤波前	滤波后	抑制率(%)	国际标准(%)
最大三相短路容量(56 MW)	5.03	1.01	80	3
最小三相短路容量(45 MW)	5.57	1.11	80.10	3

频次	THD(%)		抑制率 (%)	国际标准(%)
频次	滤波前	滤波后	抑制率 (%)	国际标准(%)
11th	0.45	0.22	51.1	1.50
13th	0.39	0.13	66.7	1.50
17th	0.30	0.06	80	1
19th	0.29	0.04	86.20	1
21th	0	0	0	0.70
23th	2.56	0.29	88.70	0.70
25th	4.17	0.41	90.20	0.70
26th	1.25	0.12	90.40	0.68