混合直流输电系统功率同步控制研究

针对一端采用传统电网换相换流阀(line commutated converter,LCC)另一端为电压源换流阀(voltage sourced converter,VSC)的混合直流输电系统因其直流侧电抗较大,造成传统双闭环矢量控制策略中电流内环的快速性与稳定性相互矛盾、暂态扰动易造成系统功率振荡等问题,提出VSC侧换流站采用功率同步控制的方法,同时,通过增加桥臂电容储能控制环,保持三相桥臂电容电压之和基本不变,抑制系统功率和直流电压波动,减小了有功功率控制环存在欠阻尼特性的影响。最后,结合模块化多电平变流器(modular multi-level converter,MMC)应用,利用仿真软件搭建双端混合直流输电系统模型,通过仿真验证了所采用方法的正确性、有效性。

Power synchronization control of hybrid HVDC

Aiming at the problems that rapadity and stability of inner current loop in traditional double loop vector control strategy is conflictive and the system power oscillation caused by transient disturbance,which were caused by the larger reactance of the hybrid HVDC (composed by traditional converter and voltage source converter) DC side.So Power Synchronization Control (PSC) method was proposed for VSC side converter.And the energy control loop of arm capacitors was proposed.It can maintain the sum of capacitor voltage in arms which is approximately constant,and suppress fluctuations of system power and DC voltage.The effect of underdamping characteristics in power control loop in PSC method was weakened.Finally,the application for modular multi-level converter (MMC) of this method was derived.In addition,the double-end hybrid HVDC model was completed in PSCAD and simulation results show that the proposed methods are correct and effective.