计及控制响应的多端混合直流输电系统短路电流近似计算方法  

Approximate Calculation Method of Short-Circuit Current of Multi-Terminal Hybrid DC Transmission System Considering Control Strategy

作　　者：李杭泽 戴志辉 石旭 杨明玉 Li Hangze;Dai Zhihui;Shi Xu;Yang Mingyu(Short-circuit current calculation,control system,network equivalence,multi-terminal hybrid HVDC transmission,line fault)

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9期2810-2824,共15页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金资助项目(51877084)。

摘　　要：多端混合直流输电系统故障发展迅速、短路电流水平超标问题严重,换流站高度非线性特征使现有短路电流求解忽略了控制系统的响应过程且多依赖建模仿真结果,无法得到短路电流的具体解析式,实现故障特性的定量分析计算。为此,该文提出三种兼顾准确性与计算复杂程度的系统模型简化措施,并在此基础上提出计及控制系统作用的短路电流复频域近似求解方法,利用Pade逼近以及分段线性化法对模型进行降阶处理,通过拉普拉斯逆变换求得短路电流的时域解析式。最后,基于PSCAD/EMTDC对不同故障距离、过渡电阻以及故障类型进行了仿真分析。结果表明,该方法能在故障的暂态阶段(10 ms内)对短路电流有较为准确的刻画,能为直流保护定值整定、断路器额定容量选取、直流输电控制策略切换以及系统规划设计等提供重要依据。The hybrid DC transmission system,which gives full play to the advantages of conventional DC and flexible DC,has become a research hotspot in the fields of long-distance transmission and renewable-energy grid connection.However,HVDC transmission lines are long and the working environment is complex,resulting in high fault probability.Once a short-circuit fault occurs on the DC line,it will generate fault current several times the rated current within 10ms,exposing the whole system to a serious overcurrent risk and threatening the sTab.operation of the system.In addition,the highly nonlinear characteristics of the converter station make the existing short-circuit current solutions ignore the response process of the control system and rely on the modeling and simulation results.It is impossible to obtain the specific analytical formula of the short-circuit current to realize the quantitative analysis and calculation of the fault characteristics,which brings difficulties to the protection and design of DC control systems and restricts the development of hybrid DC transmission technologies.Therefore,considering control response,an approximate calculation method for short-circuit current of multi-terminal hybrid DC transmission systems is proposed.First,three system model simplification measures are proposed,which take into account both accuracy and computational complexity,including port processing,non-fault-pole discharging-loop processing and AC system processing.Second,the system topology model and control model are modeled.Based on the fault-component network,the short-circuit current is obtained regardless of the action of the control system,and then the corrected current under the control action is obtained by using this calculation result.The two are superimposed to obtain the final complex frequency domain analytical formula for the short-circuit current,and the inverse Laplace transform is used to obtain the time-domain solution for the short-circuit current.The proposed method corrects the trigger angle of

关 键 词：短路电流计算 控制系统 网络等值 多端混合直流输电 线路故障 

分 类 号：TM713[电气工程—电力系统及自动化]