基于VSC-HVDC的风电场并网系统潮流算法研究

柔性直流输电系统非常适合海上风电场并网,但传统交/直流混联系统潮流算法在计算基于VSC-HVDC的风电场并网系统潮流时存在缺陷:直流系统移开后,风电场交流节点变为孤立节点,剩余交流系统的雅可比矩阵不可逆,迭代过程无法进行。针对这一缺陷提出了一种含VSC-HVDC的混联系统(AC/VSC-HVDC)潮流解耦算法:该算法将交、直流系统进行解耦,分别迭代计算。所提算法克服了目前交/直流混联系统潮流计算方法存在的对交流潮流计算程序继承性差、扩展变量多、计算速度慢等缺点;也解决了风电场VSC-HVDC并网系统潮流算法中存在的问题。通过标准算例的计算验证了所提方法的有效性,可以用来对风电场直流并网系统进行稳态潮流分析。

Research on power flow of wind farm grid-connected system based on VSC-HVDC

Flexible HVDC system is very suitable for offshore wind farm grid-connection, but when traditional AC-DC power flow algorithm is used to calculate the power flow of grid-connected wind farm based on VSC-HVDC, once removing the DC system, the wind farm becomes isolated communication node, thus the Jacobi matrix of communication system will not be irreversible and iterative process can't be continued. Aiming at these defects, this paper proposes a AC/VSC-HVDC power flow decoupled algorithm containing VSC-HVDC, by which the AC system and DC system are decoupled and computed iteratively. This algorithm overcomes the shortages of existing AC/DC hybrid system power flow calculation algorithm, such as bad inheritance to AC power flow calculation program, much expansion variables, slow calculation speed, and so on, and solves the problem of wind farm VSC-HVDC grid-connected system power folw algorithm. Calculation of standard examples verify that the proposed algorithm is valid and can be used for steady-state power flow analysis of wind farm DC grid-connected system.