海上风电柔性直流换流阀端间绝缘试验异常分析及改进方法

柔性直流输电是海上风电远距离规模化集中开发的重要技术。作为柔性直流输电的核心设备,换流阀运行工况复杂,其安全运行直接影响整个系统的可靠性与稳定性,因此必须通过系列型式试验,从运行和绝缘等方面考核换流阀的设计。针对某海上风电柔性直流输电换流阀端间绝缘耐压试验中出现的直流局部放电异常情况,分析了异常产生的原因,并提出了一种基于回路补偿的端间绝缘改进试验方法。该方法在符合相关国家标准规范的前提下,能够有效验证同类拓扑结构多重阀单元外绝缘及各个单阀之间的电压耐受能力和局部放电水平,为以后采用更高电压等级换流阀端间绝缘试验的顺利开展提供借鉴。

Abnormality Analysis and Improved Method of the Field Partial Discharge for Terminal Insulation Experiment of the MMC Valve for Offshore Wind Power Transmission

Large scale development of offshore wind power will become an important way to achieve the national energy structure adjustment and energy conservation and emission reduction goals. Flexible DC transmission is an important technology for large-scale centralized development of offshore wind power. In order to ensure the high-reliability operation of the off-shore flexible transmission project, a series of tests must be carried out to check the correctness of the converter valve design before it is delivered to the offshore site. For modular multilevel converter with symmetrical monopole topology in an offshore flexible DC transmission project, this paper analyzes the mechanism of abnormal DC partial discharge during dielectric tests on multi-valve unit. Referring to the relevant standards and the experience of previous projects, this paper studies and proposes a test method to solve the abnormal DC partial discharge measurement. On the premise of meeting the standards and specifications, this method can effectively verify the voltage withstand ability and partial discharge level of the multi-valve units with the same topology, and provide reference for the smooth development of dielectric tests on multi-valve unit with higher voltage level in the future.