基于暂态能量流的MMC-HVDC系统故障建模及仿真分析  

Fault Modeling and Simulation Analysis Method of MMC-HVDC System Based on Transient Energy Flow

作　　者：严俊[1] 陈力绪 许建中[1] 赵成勇[1] 贾秀芳[1] YAN Jun;CHEN Lixu;XU Jianzhong;ZHAO Chengyong;JIA Xiufang(School of Electrical and Electronic Engineering,North China Electric Power University,Beijing 102206,China)

机构地区：[1]华北电力大学电气与电子工程学院,北京102206

出　　处：《华北电力大学学报（自然科学版）》2022年第3期20-33,共14页Journal of North China Electric Power University：Natural Science Edition

基　　金：国家重点研发计划项目(2018YFB0904600).

摘　　要：为分析由模块化多电平换流器(modular multilevel converters, MMC)构成的高压直流(high voltage direct current, HVDC)输电系统中的直流短路故障特性,可通过关注系统中暂态能量流(transient energy flow, TEF)的分布对MMC-HVDC系统进行暂态建模与仿真分析。对于单端MMC,可基于暂态能量守恒将半桥子模块(half bridge sub-modular, HBSM)电容等效为时变电容,建立将半桥子模块动态切换与交流汇入两个因素共同考虑在内的MMC暂态模型,分别列写并求解闭锁前后的状态方程,得到精确的MMC内部故障特征与TEF分布情况。对于复杂直流电网(HVDC grid),提出一种基于电磁暂态仿真结果的TEF分析方法,不仅可根据各部分TEF特征揭示直流故障演化规律,还可通过递推计算实现对故障电流的定量分析。最后,根据TEF流动规律提出一种考虑HBSM电容电压波动范围的暂态能量抑制策略,可有效降低故障电流并为后续故障保护争取更多时间。依据PSCAD中的仿真结果对暂态模型与能量抑制策略的正确性进行验证,同时将所提TEF分析方法应用在搭建的四端直流电网中,获取其故障传播特性。In order to analyze the characteristics of DC short-circuit fault in high voltage direct current transmission system(HVDC)composed of modular multilevel converters(MMC),transient modeling and simulation analysis of MMC-HVDC system can be carried out by paying attention to the distribution of transient energy flow(TEF).For single MMC,based on transient energy conservation,the capacitance of half bridge sub-modular(HBSM)can be equivalent to time-varying capacitance.And the MMC transient model is established,in which dynamic switching of HBSM and ac import are considered.By solving state equations of the model,the fault and TEF characteristics of MMC are obtained accurately.For MMC-HVDC-Grid,a TEF analysis method based on electromagnetic transient simulation results is proposed,which can not only reveal the evolution of dc fault,but also realize quantitative analysis of fault current through recursive calculation.Based on characteristics of TEF,an energy limitation strategy considering the fluctuation range of capacitor voltage in HBSM is proposed,which can delay the blocking time effectively.According to the simulation results in PSCAD,the correctness of the transient model and the energy limitation strategy is verified,meanwhile,the TEF analysis method is applied to the four-terminal MMC-HVDC grid to obtain its fault characteristics.

关 键 词：MMC-HVDC输电系统 直流短路故障 暂态能量流 暂态等效模型 能量抑制策略 

分 类 号：TM726[电气工程—电力系统及自动化]