三相Vienna整流器於電網不平衡下考慮輸出不平衡與電壓利用率之輸入電流失真補償與輸出電壓漣波抑制之研製;Development and Implementation of input current distor-tion compensation and output voltage ripple suppression of three-phase Vienna rectifier considering output imbal-ance and voltage utilization under unbalanced power grid

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/96343

Title:	三相Vienna整流器於電網不平衡下考慮輸出不平衡與電壓利用率之輸入電流失真補償與輸出電壓漣波抑制之研製;Development and Implementation of input current distor-tion compensation and output voltage ripple suppression of three-phase Vienna rectifier considering output imbal-ance and voltage utilization under unbalanced power grid
Authors:	劉佳聖;Liu, Jia-Sheng
Contributors:	電機工程學系
Keywords:	三相Vienna整流器;中性點電流擾動抑制;三相電網不平衡;輸出電壓主動不平衡;電流零交越失真;不可合成區域;向量空間;Three-phase Vienna Rectifier;Neutral Point Current Disturbance Suppression;Three-phase Grid Unbalance;Active Output Voltage Imbalance;Current Zero-crossing Distortion;Non-synthesizable Region;Space Vector
Date:	2025-01-18
Issue Date:	2025-04-09 17:50:36 (UTC+8)
Publisher:	國立中央大學
Abstract:	三相電網不平衡下之電流諧波抑制及直流鏈電壓擾動抑制為近年來整流器研究之重要課題。其中，三相Vienna整流器因其高效率及低成本之特性，已然成為廣受關注之三階層拓樸。然而，由於Vienna整流器倚賴電流極性決定導通方向之特性，使電流於零交越時將發生失真，且此現象於輸出中性點不平衡時更加明顯。此外，在電網不平衡情況下，為抑制直流鏈二次漣波擾動，需注入實虛功漣波命令進行補償，此補償機制將導致電流與電壓產生相位偏移，而此電流與電網電壓之相位差，將使Vienna整流器操作於高調製指數下時，容易進入不可合成區域，使參考電壓向量無法有效合成，引發嚴重之電流失真及電壓擾動問題。為了減少不可合成區域對三相Vienna整流器之影響，本文提出非單位功因下電流最佳化(NUPF-CO)策略，有效降低不可合成區域對系統性能之負面影響。此策略使三相Vienna整流器同時於電網不平衡及輸出中性點主動不平衡下，仍能實現直流鏈二次漣波之抑制與避免電流發生零交越失真，並確保良好之中性點電流擾動抑制與功因校正效果。此外，本文亦經由理論分析與數值計算，詳細比較所提策略與傳統策略之可操作範圍(無過調變範圍)，並進一步推導出確保電流極性正確變換之最佳操作範圍，為系統設計提供完整之理論依據。此外，隨著再生能源與電動車充電設備的普及，電力轉換設備所面臨之電網不平衡與負載不平衡問題日益嚴重。特別是於三相Vienna整流器中，輸出中性點不平衡將導致電流零交越失真及直流側電壓擾動，進而影響整體系統效能。針對此問題，本文提出一種交軸補償策略(RZCI, Reduced Zero-Crossing Interval)，有效減少三相Vienna整流器在輸出中性點不平衡情況下之箝位區間範圍，進而降低直流側電壓擾動。且考慮到RZCI策略可能引入之電流諧波問題，制定補償範圍之上下限，確保補償後的三相Vienna整流器仍能符合國際規範所訂定的單一電流諧波限制。並且本文亦經由結合所提NUPF-CO策略、所提RZCI策略與虛擬電容前饋電流方法，經由動態調整補償權重，使Vienna整流器能同時抑制電網不平衡造成之直流鏈二次漣波擾動，以及輸出中性點不平衡導致之直流側電壓擾動，同時維持良好之功率因數校正效果並消除零交越失真。最後，本文經由實際建置2.5 kW之三相Vienna整流器進行實驗驗證，系統性地比較傳統SCIS、VJCIS策略與所提NUPF-CO策略於各種不平衡條件下之性能表現。實驗結果顯示，結合RZCI策略與虛擬電容技術的方案不僅能有效補償直流側電壓擾動，更能確保系統運行時的電流諧波符合相關規範要求，展現出優異的綜合性能。;Current harmonic suppression and DC-link voltage ripple mitigation under three-phase grid unbalance have become crucial research topics in rectifier studies in recent years. The three-phase Vienna rectifier has emerged as a widely recognized three-level topology due to its high efficiency and low-cost characteristics. However, due to its current polari-ty-dependent conduction mechanism, current distortion occurs at zero-crossing, and this phenomenon becomes more pronounced under output neutral point unbalance. Furthermore, under grid unbalance conditions, the injection of active and reactive power ripple commands is required to suppress DC-link second-order ripple disturbances. This compensation mecha-nism leads to phase shifts between current and voltage, and this phase difference between current and grid voltage can cause the Vienna rectifier to enter non-synthesizable regions at high modulation indices, where reference voltage vectors cannot be effectively synthesized, resulting in severe current distortion and voltage disturbance issues. To reduce the impact of non-synthesizable regions on the three-phase Vienna rectifier, this paper proposes a Non-Unity Power Factor Current Optimization (NUPF-CO) strategy, effectively mitigating the negative effects of non-synthesizable regions on system performance. This strategy ena-bles the three-phase Vienna rectifier to achieve DC-link second-order ripple suppression while avoiding current zero-crossing distortion under both grid unbalance and output neutral point active unbalance conditions, ensuring excellent neutral point current disturbance sup-pression and power factor correction effects. Moreover, through theoretical analysis and nu-merical calculations, this paper provides detailed comparisons of operating ranges (non-overmodulation ranges) between the proposed and conventional strategies, and further derives optimal operating ranges for ensuring proper current polarity transition, providing comprehensive theoretical foundations for system design. Furthermore, with the proliferation of renewable energy and electric vehicle charging equipment, power conversion devices are increasingly facing grid unbalance and load un-balance issues. Particularly in three-phase Vienna rectifiers, output neutral point unbalance leads to current zero-crossing distortion and DC-side voltage disturbances, affecting overall system performance. Addressing this issue, this paper proposes a Reduced Zero-Crossing In-terval (RZCI) compensation strategy, effectively reducing the clamping interval range of three-phase Vienna rectifiers under output neutral point unbalance conditions, thereby de-creasing DC-side voltage disturbances. Considering potential current harmonic issues intro-duced by the RZCI strategy, upper and lower limits for compensation ranges are established to ensure the compensated three-phase Vienna rectifier still complies with individual current harmonic limits set by international standards. This paper also combines the proposed NUPF-CO strategy, RZCI strategy, and virtual capacitor feedforward current method, with dynamic compensation weight adjustment, ena-bling the Vienna rectifier to simultaneously suppress DC-link second-order ripple disturb-ances caused by grid unbalance and DC-side voltage disturbances caused by output neutral point unbalance, while maintaining excellent power factor correction effects and eliminating zero-crossing distortion. Finally, experimental validation is conducted on a 2.5 kW three-phase Vienna rectifier, systematically comparing the performance of traditional SCIS, VJCIS strategies with the proposed NUPF-CO strategy under various unbalance conditions. Experimental results demonstrate that the solution combining RZCI strategy and virtual capacitor technology not only effectively compensates for DC-side voltage disturbances but also ensures system oper-ation current harmonics meet relevant regulatory requirements, showcasing superior com-prehensive performance.
Appears in Collections:	[Graduate Institute of Electrical Engineering] Electronic Thesis & Dissertation

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