基于柔性直流的海上风电送出系统设计与研究

Design and Research of Offshore Wind Power Transmission SystemBased on VSC-HVDC

远距离海上风电送出系统中,传统交流输电线路在经济性和技术性上均不适用于电能的传输,且传统电网换相型换流器(LCC)对风电场控制的灵活性不足。针对以上缺点,提出了一种基于柔性直流的海上风电送出系统拓扑,其中整流站采用传统的电压源型换流器(VSC),逆变站采用模块化多电平换流器(MMC),建立了其数学模型并设计了相应的控制系统。VSC-MMC的拓扑结构能够实现有功和无功功率的灵活控制,MMC则进一步减少了输出交流电压的谐波。仿真结果表明,所设计的海上风电送出系统具有良好的稳态和暂态运行特性,显著降低了交流电网的谐波水平,提高了风电并网的电能质量。

In the long-distance offshore wind power transmission system,the traditional AC transmission line is not suitable for power transmission in terms of economy and technology,and the traditional line commutated converter(LCC)is not flexible enough to control the wind farm.In view of the above shortcomings,this paper proposes a topology of offshore wind power transmission system based on VSC-HVDC,in which the rectifier station adopts traditional voltage source converter(VSC)and the inverter station adopts modular multilevel converter(MMC).Its mathematical model is established and the corresponding control system is designed.The topology of VSC-MMC can realize the flexible control of active and reactive power,and MMC further reduces the harmonic of output AC voltage.The simulation results show that the designed offshore wind power transmission system has good steady-state and transient operation characteristics,significantly reduces the harmonic distortion of AC grid and improves the power quality of wind power grid connection.