中文摘要：

针对柔性高压直流输电（VSC-HVDC）系统潮流控制灵活,能够增强系统稳定性和接入无源网络等特点,提出采用直接功率控制（DPC）法对该系统的换流控制器进行设计。该方法以瞬时无功功率理论为基础实时控制电网与换流站之间的功率交换,在系统采样频率和开关周期足够高时其功率误差非常小,从而能够保证系统对功率的快速、准确控制。同时通过使用直流电压控制器和相位补偿技术来抑制直流电压的波动和检测延迟的补偿,最后采用PSCAD软件对系统进行仿真,从仿真看出基于DPC设计的控制器能够对电网的有功和无功进行快速调节,并具有直流电压稳定、交流侧谐波含量少等优点。通过对VSC-HVDC系统的仿真验证了该系统能够快速完成电力系统潮流控制以及增强了系统运行的稳定性,该系统具有较大的实用价值。

英文摘要：

The voltage source converter-HVDC（VSC-HVDC）system has the advantages of power flow control,and can enhance system stability and supply to the passive networks.We proposed a converter controller based on direct power control（DPC）.The transmission active and reactive power in AC grid could be controlled instantly with the help of instantaneous reactive power theory.When the system had high enough sample frequency and switching cycle,the power error would be very small,which made the voltage source converter-HVDC（VSC-HVDC）to be controlled quickly and accurately.The DC voltage controller and phase compensation technique were used to damp the DC voltage fluctuations and data detects delay compensation.The system was simulated by PSCAD.It can be seen from the results that the active and reactive can be controlled quickly;the DC voltage is stable and little harmonic in the AC current.The simulation has also proved that the VSC-HVDC can realize power flow control instantly and enhance system stability,which is very useful in modern power system.