经DRU送出的海上风电交流系统潮流计算方法

power flow calculation method of DRU-based AC transmission systems for off⁃shore wind power

目前柔性直流输电系统是远海风电并网的典型方案,而整流站采用DRU(二极管不控整流单元)可以进一步提升直流系统的经济性和可靠性。因此提出基于构网型风电机组和DRU的海上风电交流系统稳态潮流计算方法。描述了基于DRU的海上风电并网系统拓扑结构,介绍了风电机组采用Q-f(无功功率-频率)下垂控制的构网型控制策略,提出了稳态潮流计算方法。该方法根据DRU换流站交流母线的无功功率不平衡量来进行潮流迭代,并计及构网型风电机组的Q-f下垂控制特性。在海上风电低频交流汇集送出系统和海上风电中频交流汇集直流送出系统中,分析了基于构网型风电机组和DRU的海上风电交流系统的稳态运行特性,验证了所提方法的有效性。

The VSC-HVDC transmission systems are the typical solution for integrating far offshore wind power.Us⁃ing diode rectifier units(DRUs)at the rectifier stations can further enhance the system’s economic efficiency and reliability.Therefore,a steady-state power flow calculation method of AC system transmission system for offshore wind power,based on grid-forming(GFM)wind turbines and DRU,is proposed.The topology of the offshore wind power integration system using DRU is described,and the GFM control strategy of the wind turbines,utilizing Q-f(reactive power-frequency)droop control,is introduced.The proposed steady-state power flow calculation method iterates the power flow using the reactive power imbalance in AC bus at the DRU-based converter station and consid⁃ers the Q-f droop control characteristics of the GFM wind turbines.The steady-state operational characteristics of AC transmission systems for offshore wind power,based on GFM wind turbines and DRU,are analyzed for both the low-frequency and intermediate-frequency AC transmission systems.The effectiveness of the proposed method is vali⁃dated.