改善直流配电网中VSC与线路交互失稳的有源阻尼策略

Active Damping Strategy for Improving VSC and Line Interaction Instability in DC Distribution Network

针对多端直流配电系统中的电力电子装置与直流网络阻抗之间的不良交互所诱发的直流电压振荡问题,提出了一种改进的有缘阻尼控制策略。以主从控制的放射状多端直流配电系统为研究对象,分析了系统电压控制核心器件—定电压源型换流器(VSC)与直流系统谐振模态的不良交互机制,并揭示了VSC稳态功率点变化所引起的系统电压控制环路对该不良交互的恶化效应。基于上述分析结果,提出了一种可分段调节系数的改进型有源阻尼控制器,该控制器通过独立调节各区频段阻尼特性,分别对源网不良谐振交互行为和VSC稳态功率变化导致的恶化效应加以抑制,实现了系统稳定性的提升。最后通过电磁暂态仿真对所提出的有源阻尼控制策略的有效性进行了验证。结果表明,相对于传统有源阻尼控制器,所提出的有源阻尼控制器能够提供更高的附加阻尼,并进一步扩大系统的稳定域。

Aiming at the DC voltage oscillation induced by the poor interaction between the power electronic device and the DC network in the multi-terminal DC power distribution system,we proposed an improved active damping control strategy.Taking the master-slave system as a research object,we analyzed the adverse interaction mechanism between the system voltage control core device,constant voltage VSC,and DC system resonant mode,and revealed the system voltage control loop which is caused by the change in the VSC steady-state power point has a degrading effect on this bad interaction.Based on the results,we proposed an improved active damping controller.The controller can independently adjust the damping characteristics of the frequency bands in each zone,respectively,and causes the poor resonance interaction behavior of the source network and the steady state power variation of the VSC.The deterioration effect is suppressed,and the stability of the system is improved.Finally,the effectiveness of the proposed active damping control strategy is verified by electromagnetic transient simulation.The results show that the active damping controller proposed in this paper can provide higher additional damping and further expand the stability domain of the system compared to the traditional active damping controller.