Comprehensive Power Quality Management for Transformerless Unified Power Quality Conditioner Under Multiple Operating Conditions

doi:10.16183/j.cnki.jsjtu.2023.281

Abstract

Abstract:

To address the power quality problems caused by power electronic loads, a two-leg topology-based transformerless unified power quality conditioner (TLTT-UPQC) is proposed, which can overcome the volume, weight, and magnetic saturation of power frequency transformer in the existing UPQCs, and can improve the power quality of the distribution network in a lightweight and highly flexible form to meet the high-quality electricity demand of loads. First, the working principle of TLTT-UPQC is analyzed from the perspective of circuit topology. Then, combined with theoretical analysis, the operating mechanisms of various power quality management functions are studied in scenarios such as grid voltage drop, rise and distortion, as well as resistor-inductance and nonlinear loads, based on which, the system control strategy is designed. Finally, a MATLAB-based simulation model is developed to verify the multifunctional operation performances of the TLTT-UPQC through simulation results.

Key words: power quality, transformerless unified power quality conditioner (UPQC), two-leg converter, power flow, multiple operating conditions

CLC Number:

TM727

FU Zhe, ZHANG Qi, LIU Yang, WAN Bohao, WANG Ting, SUN Yanfei. Comprehensive Power Quality Management for Transformerless Unified Power Quality Conditioner Under Multiple Operating Conditions[J]. Journal of Shanghai Jiao Tong University, 2025, 59(2): 252-265.

Figures/Tables 28

Fig.1

Tab.1

Fig.2

Tab.2

System state equations in different working modes

工作模态	状态表达式
模态1	L_sc $\frac{d i_{s c}}{d t}$ $d i s c d t$ =u_g-u_L+u_dcn, L_pc $\frac{d i_{p c}}{d t}$ $d i p c d t$ =u_L+u_dcp
模态2	L_sc $\frac{d i_{s c}}{d t}$ $d i s c d t$ =u_g-u_L-u_dcp, L_pc $\frac{d i_{p c}}{d t}$ $d i p c d t$ =u_L+u_dcp
模态3	L_sc $\frac{d i_{s c}}{d t}$ $d i s c d t$ =u_g-u_L-u_dcp, L_pc $\frac{d i_{p c}}{d t}$ $d i p c d t$ =u_L-u_dcn
模态4	L_sc $\frac{d i_{s c}}{d t}$ $d i s c d t$ =u_g-u_L+u_dcn, L_pc $\frac{d i_{p c}}{d t}$ $d i p c d t$ =u_L-u_dcn

Tab.2

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来源	高频变压器	电力电子开关器件个数	功率二极管个数
文献[13]	√	16	0
文献[14]	√	14	0
文献[15]	√	16	0
文献[16]	√	12	4
文献[17]	×	10	0
文献[18]	×	12	0
文献[19]	×	6	0
文献[20]	×	8	2
本文TLTT-UPQC	×	4	0

参数	数值	参数	数值
系统额定容量/(kV·A)	3×10	负荷电压u_L幅值/V	311
电网电压u_g幅值/V	311	负荷电压频率,f_L/Hz	50
电网电压频率,f_g/Hz	50	串联变换器电容,C_sc/μF	90
直流母线电压,u_{dcp, n}/V	±375	串联变换器电感,L_sc/mH	1.2
直流母线电容,C_{dcp, n}/μF	3 300	并联变换器电感,L_pc/mH	0.8
额定负载,Z_L/Ω	4.84	系统开关频率,f_s/kHz	10