引入故障恢复信号的VSC-HVDC附加阻尼控制研究

基于电压源型换流器的高压直流输电(VSC-HVDC)具有快速、灵活的有功功率和无功功率控制能力。VSCHVDC附加阻尼控制能有效地抑制交流系统的低频振荡。讨论了附加阻尼控制器的限幅环节对控制效果的影响,然后提出了引入故障恢复信号的附加阻尼控制。故障恢复信号为指数规律衰减信号,将其与附加阻尼控制器输出信号叠加,作为直流功率调制的参考信号,以减小直流功率调制前期的直流功率幅值。并在直流电压波动的允许范围内,使直流功率调制过程趋于理想的自由衰减振荡,比无故障恢复信号的附加阻尼控制衰减更快,从而显著减小限幅环节的影响。还给出了直流电压波动随直流功率波动变化的关系曲线。仿真结果验证了所提附加阻尼控制方法的有效性。

Study of using fault recovery signal for additional damping controller of VSC-based HVDC transmission system

The VSC-based high voltage DC transmission (VSC-HVDC) has the capability of fast and flexible active and reactive power control. VSC-HVDC with additional damping controller can effectively suppress low-frequency oscillation of AC system. This paper discusses how the magnitude limiter in the damping controller influences control effect, then proposes a new method of using fault recovery signal for damping controller. The fault recovery signal is a kind of exponentially decay power. By adding it to output of the damping controller as the DC power reference can reduce the magnitude of DC power at early stage of DC power modulation. Within range of allowed DC voltage ripple, the DC power modulation tends to be in an ideal free damping state, damping more rapidly in comparison with additional damping controller without fault recovery signal. Thus the influence of limiter is significantly reduced. This paper also gives the relationship curve of DC power ripple and DC voltage ripple. Simulation results validate the effectiveness of the proposed damping controller.