面向海上平台轻型化的跟网型中频远海风电场直流送出方案

海上风电具有广阔的发展前景,而可靠、高效的大规模远海风电并网系统是开发海上风电的关键技术.针对远海风电直流送出系统的海上平台轻型化问题,提出一种跟网型中频远海风电场直流送出方案.该方案采用跟网型风电机组,直流系统的整流侧和逆变侧都采用模块化多电平换流器(MMC).首先,从拓扑结构和控制系统2个方面对该跟网型中频方案进行了描述;接着,就海上风电场交流系统运行频率对风电场及其直流送出系统的影响进行了分析,包括对变压器、交流电缆和MMC等的影响.基于±320 kV/1000 MW海上风电直流送出系统,分析了100 Hz跟网型中频方案的技术经济性,包括关键电气设备的主回路参数、海上交流电缆造价、海上平台造价、风机造价、交流电缆损耗和整流站阀损耗、交流电缆输电能力.最后,在PSCAD/EMTDC中搭建了跟网型中频方案的电磁暂态仿真模型,验证了该方案的有效性.

HVDC Transmission Scheme of Grid-following Medium-frequency Distant Offshore Wind Farm for Offshore Platform Miniaturization

Offshore wind power has promising development potential, and reliable and efficient large-scale distant offshore wind power grid integration system is the key technology to develop the offshore wind power. Aiming at the miniaturization problem of offshore platform for distant offshore wind power HVDC transmission system, an HVDC transmission scheme for the grid-following medium-frequency distant offshore wind farm is proposed. This scheme utilizes the grid-following wind turbines, where the modular multilevel converters (MMCs) are installed on both the rectifier side and the inverter side of HVDC system. Firstly, the grid-following medium-frequency scheme is described from two aspects of topology and control system. Then, the influence of the offshore AC system operation frequency on the offshore wind farm and its HVDC transmission system is analyzed, including influence on the transformer, the AC cable and the MMC. Based on a ±320 kV/1 000 MW offshore wind power HVDC transmission system, the technical and economic efficiency of the proposed 100 Hz grid-following medium-frequency scheme is analyzed, including the main circuit parameters of key electrical equipment, the cost of AC cable, the cost of offshore platform, the cost of wind turbines, the AC cable loss and rectifier station valve loss, and the transmission capability of AC cables. Finally, an electromagnetic transient simulation model of the grid-following medium-frequency scheme is built in PSCAD/EMTDC to verify the effectiveness of the scheme.