多端柔性直流输电系统在风电场中的应用

Research on Multiterminal VSC-HVDC System for Wind-Farms

基于电压源型换流器(voltage source converter,VSC)的多端直流输电系统(VSC-MTDC)是理想的风力发电与电网联接的输电方式。分析基于双馈感应发电机的风电场输出特性以及VSC-MTDC的基本原理与控制方法,提出适用于风电场的VSC-MTDC系统的多点直流电压控制策略。利用PSCAD/EMTDC对该控制方法进行仿真,结果表明,该控制方法能实现定功率与定直流电压控制模式间的自动转换,确保定直流电压控制的换流站故障退出以及其他故障后直流电压的稳定控制与风电场的可靠输出。

The voltage source converter （VSC） based multiterminal VSC-HVDC power transmission system （VSC-MTDC） is an ideal approach to connect wind farm with power grid. Analyzing the output characteristics of wind farm equipped with doubly fed induction generators as well as the basic principle and control strategy of VSC-MTDC, a multiterminal DC voltage control strategy suitable to wind farm connected with VSC-MTDC is proposed. By use of PSCAD/EMTDC, the proposed control strategy is simulated, and simulation results show that using the proposed control strategy the conversion between constant power control mode and constant DC voltage control mode can be automatically implemented, thus the DC voltage stability control and reliable power output of wind farm can be ensured after the fault-caused outage of converter station controlled by constant DC voltage and under other faults.