混合多端直流输电系统限流控制策略配合及限流参数全局优化  

Current Limiting Control Strategy Coordination and Global Optimization Method of Current Limiting Parameters for Hybrid Multi-Terminal DC Transmission System

作　　者：李杭泽 戴志辉 韩哲宇 奚潇睿 牛宝仪 杨明玉 Li Hangze;Dai Zhihui;Han Zheyu;Xi Xiaorui;Niu Baoyi;Yang Mingyu(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Resources,North China Electric Power University,Baoding,071003,China)

机构地区：[1]新能源电力系统全国重点实验室(华北电力大学),保定071003

出　　处：《电工技术学报》2024年第11期3323-3338,共16页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金资助项目(51877084)。

摘　　要：混合多端直流输电系统短路电流水平超标对其安全稳定运行造成极大威胁。现有通过控制策略限流的方法多以本站出口侧最严重的极间故障展开分析,忽略了过渡电阻对两侧系统的耦合作用,且控制参数的不合理配置会降低故障点非零电位大小,进而加剧线路过电流现象。为此,首先,阐述了混合多端直流输电系统常见控制限流策略;其次,对换流站自身的控制特性及站间交互作用对故障电流的影响机理展开分析,提出计及过渡电阻耦合作用下故障电流的计算方法;然后,在此基础上,综合考虑控制参数灵敏性、限流效果等约束,建立控制参数全局优化数学模型,通过层次分析法得到控制参数的最优解;最后,基于PSCAD/EMTDC对传统限流特性及全局优化下的限流特性进行对比分析。结果表明,所提方法能在提高限流效果及满足参数灵敏性的基础上更好地适应经过渡电阻故障的情况,降低故障时电流上升率和电流峰值,协助降低两侧换流站因增流现象加剧线路过电流情况而闭锁的概率。Hybrid DC transmission technology effectively improves the interconnection between AC systems and new energy resources,and becomes a new way for large-scale wind power,photovoltaic and other new energy to connect to the power grid.However,once a short-circuit fault occurs in the DC line,the stable operation of the system will be seriously threatened by the rapid growth of DC fault currents.Therefore,it is necessary to take corresponding current-limiting measures to suppress the rapid growth of fault currents.The selection of current-limiting control parameters of the existing system is mostly oriented to the fault current characteristics of the local converter station,so that the overcurrent of the local system may be aggravated by the coupling effect of the fault resistance after the active current-limiting is adopted in the far-end system.Therefore,a calculation method of the fault current of the hybrid multi-terminal DC transmission line considering the coupling effect of the fault resistance is proposed after investigating the phenomenon and reasons of the exacerbated over current along local station lines after the start of the current-limiting link at the far-end converter station,and the current-limiting parameters are globally optimized to better adapt to short circuits through fault resistance.In terms of the calculation of fault current,the characteristics of voltage dependent current order limiter(VDCOL)strategy for LCC rectifier stations and active current-limiting strategy for MMC inverter stations are fully considered,and the influence mechanism of the interaction of control characteristics between converter stations on line fault current is clarified.The influence of different control parameters of LCC and MMC on the system's current-limiting capability is analyzed by sensitivity index.According to the response characteristics of the control system and the timing coordination logic between the control systems of the converter station,a three-stage fault current transient characteristic division pri

关 键 词：主动限流控制 低压限流 混合多端直流输电 过渡电阻 参数优化 

分 类 号：TM713[电气工程—电力系统及自动化]