基于动态交互能量的直流孤岛频率紧急控制方法

Emergency Frequency Control Method for DC Island System Based on Dynamic Interaction Energy

  • 摘要: 针对高压直流输电系统进入孤岛运行状态后,因功率不平衡导致频率失稳的问题,提出一种基于动态交互能量的直流孤岛频率紧急控制方法。首先,建立直流孤岛外送系统的状态空间模型,根据控制环节的响应差异,利用首次积分法构造了含能量存储项、耗散项和交互项的系统能量模型。然后,分析不同能量项对频率稳定性的影响,揭示正交互能量项是劣化系统稳定性的直接因素。在此基础上,以最大程度降低直流孤岛系统正交互能量为目标,构造正交互能量补偿支路,对整流器电流指令值进行实时调节,实现送端电网功率差额的紧急补偿和系统频率波动的快速平抑。最后,在RT-LAB平台搭建直流孤岛外送系统模型,对所提方法进行验证。实验结果表明,提出的直流孤岛频率紧急控制方法可以显著降低正交互能量对系统稳定性的不利影响,实现系统频率的快速平稳恢复。

     

    Abstract: To address the issue of frequency instability caused by power imbalance when HVDC transmission system enters the island operation state, an emergency frequency control method based on dynamic interactive energy is proposed. Firstly, a state-space model for the DC island transmission system is established. According to the response differences of control links, a system energy model is constructed involving the energy storage term, dissipation term, and interaction term using the first integral method. Then, the influence of different energyterms on frequency stability is analyzed, and it is revealed that the positive interaction energy term is the direct factor contributing to the stability of the degraded system. On this basis, with the aim of minimizing the positive interaction energy of the DC island system, a positive interaction energy compensation branch is constructed. This branch dynamically adjusts the rectifier current command value to realize urgent compensation for the power difference of the sending network and achieve rapid stabilization of system frequency fluctuations. Finally, a DC island transmission system model is built on the RT-LAB platform to verify the proposed method. The experimental results demonstrate that the proposed DC island frequency emergency control method can significantly reduce the negative influence of positive interaction energy on system stability and enable the rapid and stable recovery of system frequency.

     

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