PLL-Based Feed-Forward Control to Attenuate Low-Frequency Common-Mode Voltages in Transformerless LVDC Systems

Oliveira, Thiago Ribeiro de; Silva, Waner Wodson A. G.; Seleme, Seleme I.; Donoso-Garcia, P.F.

doi:10.1109/tia.2019.2891435

Cited by 7 publications

(3 citation statements)

References 21 publications

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“…According to [26][27][28], zero-sequence components are coupled through the neutral line, which leads to low-frequency CM voltage in the three-phase four-wire system. The literature [29][30][31] has presented a low-frequency CM voltage compensator, and a study [32] proposed a feedforward compensation method for low-frequency CM voltage suppression. Both of these methods are only for single-phase systems; the low-frequency CM voltage in three-phase systems has been not studied.…”

Section: Introductionmentioning

confidence: 99%

A Transformerless Converter with Common-Mode Decoupling in Low-Voltage Hybrid Grids

Wang,

Zhang,

Han

et al. 2024

Processes

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Compared with isolated converters, transformerless converters are a preferred choice in low-voltage grids due to their efficiency and lower cost. However, leakage current and common mode (CM) voltage appear through the converter and ground in hybrid grids, which consist of AC and DC subgrids. The leakage current and CM voltage seriously influence operation and power quality in low-voltage distribution systems. This paper proposes a common-ground-type (CGT) converter equipped with a CM decoupling control strategy to eliminate the leakage current and CM voltage. A CM model is derived, and the leakage current and CM voltage are analyzed in detail. A CGT four-leg converter is constructed to eliminate the high frequency CM voltage. A dual DQ current control loop is developed to suppress the DC double-frequency ripple. Additionally, an active damping method is proposed, based on the neutral current feed-forward plus inductor current feedback, to attenuate the low frequency CM voltage. The proposed converter and control strategy guarantees excellent performance in suppressing leakage current and CM voltage. The DC voltage of the converter connected to the DC grid maintains stability and symmetry. The leakage current is significantly reduced, and the leakage current suppression performance is improved by 83%. The high frequency CM voltage is attenuated from 50%udc to 2%udc, and the low frequency CM voltage is suppressed from approximately 32%udc to 3%udc, which is a significant improvement compared with the traditional method. In addition, the proposed control strategy has good transient performance when the load changes abruptly. Finally, an experimental platform is established to validate the feasibility and performance. The experiment results showed that the proposed control strategy improves the system performance and power quality.

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Section: Introductionmentioning

confidence: 99%

A Transformerless Converter with Common-Mode Decoupling in Low-Voltage Hybrid Grids

Wang,

Zhang,

Han

et al. 2024

Processes

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 99%

“…In the transformerless mode, it is especially important to pay attention to protection issues and elimination of leakage current. Different solutions have been attempted to eliminate or reduce the leakage current by providing novel structures or modified modulation techniques that decouple AC and DC sides [19][20][21][22][23][24]. Recent studies about DC grounding have examined only the types of grounding, its configurations in DC microgrids, and the effect of the type of grounding on the types of faults [25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Grounding and Isolation Requirements in DC Microgrids: Overview and Critical Analysis

Azizi,

Husev,

Veligorskyi

et al. 2023

Energies

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DC microgrids, along with existing AC grids, are a future trend in energy distribution systems. At the same time, many related issues are still undefined and unsolved. In particular, uncertainty prevails in isolation requirements between AC grids and novel microgrids as well as in the grounding approaches. This paper presents a critical technical analysis and an overview of possible grounding approaches in DC systems and the feasibility of avoiding isolation between AC and DC grids.

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Evaluation of single-phase interlinking converter topologies for hybrid AC/DC microgrids considering efficiency and cost

2023

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PLL-Based Feed-Forward Control to Attenuate Low-Frequency Common-Mode Voltages in Transformerless LVDC Systems

Cited by 7 publications

References 21 publications

A Transformerless Converter with Common-Mode Decoupling in Low-Voltage Hybrid Grids

A Transformerless Converter with Common-Mode Decoupling in Low-Voltage Hybrid Grids

Grounding and Isolation Requirements in DC Microgrids: Overview and Critical Analysis

Evaluation of single-phase interlinking converter topologies for hybrid AC/DC microgrids considering efficiency and cost

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