直流电网直流短路故障电流计算方法研究进展

Research Progress of Calculation Method of DC Short-circuit Current in Flexible HVDC Grid

柔性直流电网直流侧短路故障传播机理研究是保护控制与故障清除的基础。针对不断涌现的短路电流计算方法,基于其特殊性及技术要求,首先从关键设备建模的角度,分别对比了采用不同换流器模型、不同线路模型、不同故障类型建模、含限流装置的模型、附加控制模型时计算方法的特点。然后,从状态方程列写及求解的角度,将现有方法分为全网等值求解类、方程近似求解类和仿真预测类,对比各类方法的等值与简化求解过程,指出其优缺点。进一步地,在PSCAD/EMTDC中分别搭建不同直流电网模型,从精度与速度、复杂电网适性三个维度对典型方法进行详尽对比,并总结了多种方法的适用场景。最后,根据未来复杂直流电网多节点、高耦合的特点,建议该领域围绕故障特性的高效解析和计算平台研发这两个方向展开研究。

Research on propagation mechanism of dc side short-circuit fault in high voltage direct current(HVDC)grid is the basis of protection control and fault clearing.Aiming at the emerging short-circuit current calculation methods,based on their particularities and technical requirements,from the key equipment modeling,the characteristics of calculation methods using different converter models,line models,fault type models,models with current limiting devices and additional control models are compared horizontally.Then,from the point of view of the formulation and solution of state equations,the common methods are divided into the whole network equivalent solution method,the equation approximate solution method and the simulation or prediction method.Their advantages and disadvantages are pointed out by comparing the equivalent and simplified solution processes of various methods.Furthermore,different HVDC grid models are built in PSCAD/EMTDC respectively,typical methods are compared in detail from three dimensions:accuracy and speed,and adaptability of complex HVDC grid,and the applicable scenarios of various methods are summarized.Finally,facing the multi-terminals and high coupling characteristics of complex HVDC grid in the future,it is suggested that this field should develop in two directions:efficient analysis of fault characteristics and research computing platform.