Control Strategy of Single-Phase UPQC for Suppressing the Influences of Low-Frequency DC-Link Voltage Ripple

The single-phase unified power quality conditioner (UPQC) is widely used to improve power quality for sensitive end-users. However, the inherent instantaneous power difference between parallel and series converter will generate significant low-frequency dc-link voltage ripple and degrade the compens...

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Bibliographic Details
Published in:IEEE transactions on power electronics 2022-02, Vol.37 (2), p.2113-2124
Main Authors: Meng, Linghui, Ma, Lan, Zhu, Weiwei, Yan, Han, Wang, Tiangxiang, Mao, Wenjun, He, Xiaoqiong, Shu, Zeliang
Format: Article
Language:English
Subjects:
Capacitance
Capacitors
Compensation
Converters
DC-link voltage feedback
Electric potential
Feedback control
Harmonic analysis
Harmonic distortion
influence of dc-link voltage ripple suppression
low-frequency voltage ripple
Modulation
Notch filters
Power quality
Power system harmonics
Ripples
single-phase unified power quality conditioner (UPQC)
specific order harmonics compensation
Voltage
Voltage control
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Summary:The single-phase unified power quality conditioner (UPQC) is widely used to improve power quality for sensitive end-users. However, the inherent instantaneous power difference between parallel and series converter will generate significant low-frequency dc-link voltage ripple and degrade the compensation performance of UPQC. The mechanism of dc-link voltage ripple generation and its influences on compensation voltage and current are analyzed in this article. To suppress the influence, a control strategy is proposed for the single-phase UPQC. For parallel converter, a notch filter is introduced in the outer voltage loop to prevent the voltage ripple entering the control loop, the specific order harmonics compensation is proposed in the inner-current loop to reduce the grid current harmonics. For the series converter, the dc-link voltage feedback is adopted to suppress the influence of voltage ripple on the compensation performance. Simulation and experimental results show that the grid current total harmonic distortion (THD) can be reduced effectively with the fixed dc-link capacitance compared with the traditional control strategy. More than half of the load voltage THD are also decreased by the dc-link voltage feedback control. Moreover, with the smaller dc-link capacitance, single-phase UPQC can maintain the better performance under the proposed control strategy.
ISSN:0885-8993
1941-0107
DOI:10.1109/TPEL.2021.3106049