大规模海上风电经VSC-HVDC并网后电能质量问题分析

Analysis on power quality problem of large-scale offshore wind power grid-connected via VSC-HVDC

由于海上风速的多变性,同时风机组中存在大量电力电子器件等原因,其并网后所产生的电能质量问题不容忽视。对于离岸较远的大规模海上风电场,基于电压源换流器的高压直流输电(VSC-HVDC)凭借其独特的技术优势未来将成为不可或缺的输电技术。为保证电能质量符合标准,需在并网前对电能质量作出分析。根据风电场等值原理,运用PSACD/EMTDC仿真软件搭建由双馈异步风机组成的大规模海上风电场经VSC-HVDC并网模型,研究其在风速波动下闪变、谐波电压与电流、电压偏差等电能质量问题。结果表明,在风速波动时谐波问题比较严重,实际工程中应充分考虑当地风资源的状况,制定合理的滤波方案,为今后海上风电并网的电能质量分析工作提供借鉴与参考。

The power quality problems caused by the grid-connection cannot be ignored because of the variability of offshore wind speed and the existence of a large number of power electronic devices in wind turbines.As for large-scale offshore wind farms far from the shore,voltage source converter based high voltage direct current(VSC-HVDC)will become an indispensable power transmission technology in the future due to its unique technical advantages.The power quality should be analyzed before grid-connection to ensure that the power quality meets the standards.The PSACD/EMTDC simulation software is used on the basis of equivalence principle of wind farms to build a model of large-scale offshore wind farm composed of DFIG connected to the grid via VSC-HVDC.The power quality problems such as flicker,harmonic voltage and current,and voltage deviation occurring as wind speed fluctuation are researched.The results show that the harmonic problem is serious when the wind speed fluctuates.In practical projects,the local wind resources should be fully considered and reasonable filtering schemes should be formulated.It provides a reference for the power quality analysis of the offshore wind power′s grid-connection in the future.