基于模块化思想的LCC-HVDC改进小信号建模及交互稳定性分析

随着电网换相型高压直流输电(line commutated converter based high voltage direct current, LCC-HVDC)技术的广泛应用，交直流混联电力系统的交互稳定性问题日益突出。首先基于状态空间平均法建立了考虑非线性换相重叠动态过程的LCC换流器传递函数模型。为适应愈加复杂的直流输电系统建模，提出利用模块化思想分别建立LCC-HVDC各子系统小信号模型，并推导了能反映交直流系统和换流器之间电气耦合特性的接口矩阵实现子系统连接，从而模块化建立精确且易于扩展的计及控制链路延时和锁相环输出相位波动的双端LCC-HVDC系统改进小信号模型。最后分析了控制系统参数和控制链路延时对系统小干扰稳定性的影响以及失稳模态的主导因素，揭示了双端LCC-HVDC系统交直流混合谐振机理及送受端交互影响具体过程。研究结果可以为系统参数设计、谐振抑制措施提供理论基础。

Improved small signal modeling and interaction stability analysis of LCC-HVDCbased on modularization

With the widespread application of line commutated converter based high voltage direct current (LCC-HVDC) technology, the interactive stability problem of AC-DC hybrid power systems is becoming increasingly prominent. This paper first establishes the transfer function model of an LCC converter considering the nonlinear commutation overlapping dynamic process based on the state-space averaging method. To accommodate more complex DC transmission system modeling, it is proposed to establish small-signal models of LCC-HVDC subsystems using a modularization idea, and the interface matrix reflecting the electrical coupling characteristics between AC/DC system and converter is derived to realize subsystem connection, thereby modularly establishing accurate and easily expandable small-signal models of double-ended LCC-HVDC system. These consider the control time delay and phase fluctuation of phase-locked loop output. Finally, the influence of control system parameters and control time delay on the small disturbance stability of the system and the dominant factors of the instability modes are analyzed. The mechanism of AC-DC hybrid resonance of double-ended LCC-HVDC system and the interaction between sender and receiver are revealed. The research results can provide a theoretical basis for the design of system parameters and resonance suppression measures.