含有多馈入直流的交直流混合电网高压直流建模研究

讨论了目前研究交、直流混合电网时在直流建模方面存在的模型过度简化及模型选用不恰当问题；分析了稳定性研究中直流建模的一般方法，指出了简单模型、响应模型和详细模型的基本特征；基于NETOMAC环境，以中国南方电网为原型对改进的直流响应模型和直流详细模型进行了建模和仿真对比研究，分析了两种模型的优、缺点和适应性；对含有多馈入直流且直流落点邻近的南方电网，探讨了现有HVDC建模方法在研究大扰动下交直流相互影响及直流换相失败对邻近交直流系统的影响方面存在的明显不足。从基于动态相量法计及电压畸变的新直流相量模型研究和基于机电／电磁暂态模型的交直流混合仿真算法研究两个截然不同的角度提出了可行的直流建模研究思路。研究成果为含有多馈入直流的交直流混合电网的安全稳定分析提供了建模依据和参考，也为仿真分析多直流逆变站的连锁换相失败问题提供了新的解决思路。

RESEARCHES ON HVDC MODELING FOR AC/DC HYBRID GRID WITH MULTI-INFEED HVDC

The problems existed in HVDC modeling of the AC/DC hybrid grid, including over-simplification and improper choice of the model are discussed. The general HVDC modeling methods in stability studies are introduced with the characteristics of three typical models, i.e. the simple model, the response model and the detailed model being analyzed. Digital simulation by NETOMAC program with the south China power grid as prototype is developed to compare the performance and the adaptability of two advanced DC models: the improved response model and the detailed model. For AC/DC hybrid south China power grid with multi-infeed HVDC lines located in the vicinity, the paper discusses the disadvantages of existed HVDC models in the analysis of the AC/DC interactions under large disturbances and the influence of the DC commutation failure to nearby AC/DC systems. On the bases of the above analysis, two feasible research directions for the HVDC modeling, i.e. development of new HVDC phasor model based on the dynamic phasor theory with consideration of the voltage distortion or development of novel digital hybrid algorithm to combine the electromechanical and the electromagnetic models, are proposed. Researches in this paper not only provide reference for the HVDC model choice in stability studies of the AC/DC hybrid grid but also suggest new ideas for researches on the chain DC commutation failures phenomenon that may occur to the multi-neighboring-inverters of a hybrid AC/DC power system.