海上风电柔性直流送出换流站MMC换流阀损耗研究

海上风电柔性直流送出是目前柔性直流输电领域的研究热点,损耗是柔性直流换流站的一个重要技术指标,关系着柔性直流系统的输电效率和换流阀的设计。针对输电容量为1000 MW的海上风电柔性直流送出换流站MMC换流阀损耗特性,研究了换流阀损耗的计算方法和关键计算参数的获取方法,计算得到了换流阀损耗的组成和±320 kV/1000 MW海上风电柔性直流送出工程送/受端换流站换流阀的损耗率。同时,研究了联接变压器阀侧三次谐波注入、换流器调制比和直流极线电压对换流阀损耗率的影响,结果表明:在联接变压器阀侧注入三次谐波和增大换流器调制比可减小换流阀损耗率;在相同输送容量的前提下,增大直流极线电压可减小换流阀损耗率。

Study on Loss of MMC Converter Valve Applied in Converter Station of Offshore Wind Power VSCHVDC Transmission

At present, the VSC HVDC transmission of offshore wind power is a research hotspot in the field of flexible DC transmission. Loss is an important technical index of VSC HVDC converter station, which is related to the transmission efficiency of VSC HVDC system and the design of converter valve. Therefore, a loss calculation study on MMC converter valve of VSC HVDC converter station applied in offshore wind power transmission with a transmission capacity of 1000 MW is carried out. The calculation method of valve loss and the acquisition method of key calculation parameters are studied. The composition of valve loss and the loss rate of valve at the converter station at the sending/receiving end of ±320 kV/1000 MW VSV HVDC project applied in wind power transmission are calculated. The effects of third harmonic injection, converter modulation ratio and DC pole line voltage on the valve loss rate are studied. The results show that the valve loss rate can be reduced by injecting the third harmonic at transformer valve side and increasing the converter modulation ratio, and under the same transmission capacity, the valve loss rate can be reduced by increasing the DC pole line voltage.