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   POWER CAPACITOR & REACTIVE POWER COMPENSATION

 
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  • Editor in Chief: Zhou Huigao
  • Editor in Chief: Yang Peixia
  • ISSN:1674-1757
  • CN:61-1468/TM
  • Postal Code: 52-13
  • Publication cycle: bimonthly
  • Founded in 1980
  • Host: China XD Group Co., Ltd

 

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    Volume 47 期 4，2026 2026年第47卷第4期

    • Key Technologies for the Full-chain Localization of Polypropylene Film Capactors

      YAO Lulu, YI Chengqian, LIU Gang, MENG Sen, YANG Yun

      DOI：10.14044/j.1674-1757.pcrpc.2026.04.001
      摘要：To evaluate the long-term operating performance and engineering applicability of domestically developed dry-type DC capacitors in flexible DC transmission projects, a systematic investigation was carried out on 20 all-domestic 2.8 kV~9 mF capacitors that had been in continuous service for 1~2 years at the Longmen converter station of the Kunliulong HVDC Transmission Project. The work was organized by the leading project unit and completed on the capacitor evaluation and reliability verification platform of the National Engineering Research Center of UHV Technology and Novel Electrical Equipment Basis. Electrical characteristics, encapsulation condition, and long-term operating reliability of the capacitors were evaluated through whole-unit testing and post-operation disassembly analysis. The results show that the capacitors remained in stable operating condition after long-term field service, with no obvious capacitance degradation and only minor variation in dielectric loss. Good electrical stability and insulation performance were maintained during operation. DC withstand voltage and endurance tests were further conducted on dissected capacitor elements, and all tested samples met the requirements of NB/T 11388—2023. In the endurance test, the operating duration exceeded the 500 h requirement specified in the standard. Further analysis indicates that the domestically developed capacitors can satisfy current engineering application requirements in terms of material compatibility, self-healing behavior, and structural design. Some samples still showed room for improvement in encapsulation consistency and local stress control. Overall, the investigated capacitors demonstrated good operating stability and reliability after field application, providing useful reference for subsequent design improvement, quality evaluation, and engineering application of domestic dry-type DC capacitors in HVDC systems.  
      关键词：DC dry-type capacitor;domestic production;grid-connected operation;withstand voltage characteristics;engineering application   
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      LIU Yufei, LIN Zhihui, CHEN Yuhui, WANG Yuhan, YI Chengqian, YU Qiong, LI Jiantao, WEI Jun, ZHOU Chunhong

      DOI：10.14044/j.1674-1757.pcrpc.2026.04.002
      摘要：DC-link capacitors are a bottleneck restricting the development of VSC-HVDC transmission projects, and there is currently no large-scale appliction of domestically developed capacitors in existing operational projects. Multiple types of domestically produced DC-link capacitors that have undergone gridconnected trial operation at a converter stations are subjected to disassembly analysis and test research, defects are identified, process improvements are implemented, and exploration of test scheme optimization is carried out. The results indicate that the maximum capacitance attenuation rate before and after grid connection is-0.24%, with no significant deterioration in electrical performance. Disassembly and experimental analysis reveals such four typical types of defects as abnormal withstand voltage level of the elements, improper control of potting compound dosage, delamination between the encapsulation shell and the polyurethane, as well as the presence of bubbles within the polyurethane. Accordingly, such corresponding improvement measures as staggered design of the metallized film transition zone, capacitive liquid-level sensing for potting compound monitoring, surface micro-texturing of the encapsulation shell, and precise control of vacuum degassing parameters are proposed. To address the issue that conventional parameters can hardly reflect the aging degree of DC-link capacitors, it is proposed that the capacitance variation curve during the step voltage withstand test can effectively characterize the early aging degree of capacitors. Through the state analysis, process improvements, and test scheme optimization after grid-connected operation, the reliability of the domestically produced DC-link capacitors has been enhanced, proving the feasibility of replacing imported products.  
      关键词：DC-link capacitor;domestically produced;grid-connected trial operation;disassembly analysis;process improvement   
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      更新时间：2026-08-26

      ZUO Qianglin, HE Binghui, HUANG Jie, NI Yan

      DOI：10.14044/j.1674-1757.pcrpc.2026.04.003
      摘要：In this paper, the influence of such basic performance parameters of polyurethane (PU) adhesives as dielectric constant, conductivity, and tangent of loss angle on the AC partial discharge performance of DC-link capacitors to the case is analyzed. The influence of temperature on the curing reaction of polyurethane and the effect of residual uncured rubber are also analyzed. The problem of incomplete reaction of functional groups in PU main agent is analyzed. The influence of the vacuum degree of injection on the partial discharge of the capacitor is calculated in combination with the Paschen's law. Such three curing processes of two-component PU adhesives for DC-link capacitors as high-temperature curing, normal temperature curing, and mixed curing and their influence on the performance of PU adhesives are described. The influence mechanism of the changes in the basic performance parameters of PU on the stability of capacitor partial discharge and the influence mechanism of temperature on DC-link capacitors are obtained. It is concluded that the lower the curing temperature of PU, the worse the uniformity of PU curing, and consequently the worse the case partial discharge performance and its stability. It is inferred that the higher the vacuum pressure during potting, the higher the breakdown field strength of micro-voids. The the suggestion that the basic performance parameters of PU should not exhibit abrupt changes is proposed.  
      关键词：polyurethane;DC-link capacitor;partial discharge;Paschen's law;curing reaction   
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      更新时间：2026-08-26

      DONG Xiaoliang, WU Zeyi, CHEN Deling, ZHANG Yan, ZHAO Dan, HAO Linlin, LIU Xianbo, ZHANG Chengcheng

      DOI：10.14044/j.1674-1757.pcrpc.2026.04.004
      摘要：VSC-HVDC-link capacitors are key energy storage components in sub-modules of modular multilevel converters (MMC), and their equivalent series inductance (ESL) directly affects the system's switching overvoltage and reliability. In this paper, the planar single-cell core arrangement structure is taken as the study object and a integrated inductance simulation model using COMSOL Multiphysics is set up. The influence of such five key parameters as element diameter (number of parallel elements), copper plate thickness, film width, electrode configuration, and length-to-height ratio on the overall ESL is systematically investigated. The study results show that the electrode system is the absolutely dominant factor in the overall ESL, contributing 97.1%~98.3%, while the contribution of the components themselves is less than 3%. The element diameter has a relatively minor effect (with increase of 6.6%). When the copper plate thickness is increased from 0.4mm to 2.0 mm, the ELS is decreased by only 0.19%, indicating that the effect of the copper plate thickness is not significant. The ELS is decreased by 44.5 when the film width is reduced from 150 mm to 60 mm. The copper strip with braided wire configurations exhibits an ESL 1.20~1.63 times higher than that of the solid copper plates. Moreover, increasing the aspect ratio ( L/H) from 0.62 to 2.57 yields, an ESL reduction of about 75.7%. The short circuit discharge method is used to experimentally validate five typical samples. The maximum relative error between simulations and measurement does not exceed 5.0%, which verifies the effectiveness of the model and provides a systematic quantitative basis for the optimal design of low inductance DC-link capacitors  
      关键词：VSC-HVDC transmission;DC-link capacitors;equivalent series inductance(ESL);systemlevel simulation;parametric scanning;COMSOL simulation   
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      更新时间：2026-08-26
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