基于配电网全架构精确电磁暂态模型的VT一次侧过流机理及影响因素分析  

Analysis of VT Primary Side Overcurrent Mechanism and Influencing Factors Based on Accurate Electromagnetic Transient Model of Distribution Network Structure

作　　者：郑雅玲 韩永霞[1] 余菲 陈燕萍[1] 张易民 夏子鹏 谢天权 柏林 ZHENG Yaling;HAN Yongxia;YU Fei;CHEN Yanping;ZHANG Yimin;XIA Zipeng;XIE Tianquan;BO Lin(School of Electric Power Engineering,South China University of Technology,Guangzhou,Guangdong 510641,China;CSG Guangdong Zhuhai Power Supply Bureau,Zhuhai,Guangdong 519000,China)

机构地区：[1]华南理工大学电力学院,广东广州510641 [2]南方电网广东珠海供电局,广东珠海519000

出　　处：《广东电力》2023年第1期48-58,共11页Guangdong Electric Power

基　　金：广东电网有限责任公司规划专题项目(0002200000074169)。

摘　　要：中压配电网中,电磁式电压互感器(voltage transformer,VT)本体故障及高压熔丝熔断故障频繁发生。为此首先理论分析切除线路时VT过流机理及影响因素,包括线路运行状态、负载差异、馈线数量、不同位置开关动作等。其次,基于PSCAD/EMTDC建立横琴新区20 kV配电网全架构精确电磁暂态仿真分析模型,即考虑全站及全线路实际接线的等效模型,通过理论和仿真验证VT低频振荡的过流机理和影响范围。然后,结合理论和仿真分析指出,切除故障电缆、配电变压器空载、投运馈线数量较少等工况下VT过流现象更严重,且不同位置开关动作时,VT电流具有较大的随机性。之后,结合理论和前述仿真结果的分析,提出能够保证计算结果精确度的简化模型,即采用最高运行电压或者系统等值电源模拟电源且仅建立被操作馈线的详细电磁暂态仿真模型,在保证仿真精度的同时降低建模复杂度并提高计算效率。最后,提出采用就近隔离故障及提高VT热容量的方法改善VT高压熔丝熔断问题。In the medium voltage distribution network,the body fault and high fuse fault of the electromagnetic voltage transformer(VT)frequently occur.Therefore,this paper firstly theoretically analyzes the mechanism of VT overcurrent during line cutting and the influencing factors of low-frequency oscillation current,including line running state,load differences,feeder numbers and position differences of action circuit breakers.Secondly,the complete electromagnetic transient simulation analysis model of 20 kV distribution network system of three stations in Hengqin new area is established based on PSCAD/EMTDC,that is the equivalent model considering the actual connection of the whole station and the whole lines,and the low-frequency oscillation overcurrent mechanism and influence range of VT are verified through theory and simulation.Then,combined with the theory and simulation analysis,it is proposed that VT overcurrent is more serious when the faulty cable is cut off,the distribution transformer is unloaded,and the number of feeders is small.In addition,VT current has great randomness when the switch is operated at different positions.Finally,according to the analysis of theory and simulation results,a simplified model that maintains accurate calculation results is proposed to use the highest operating voltage or equivalent power to simulate the power supply,and only establish a detailed electromagnetic transient simulation model of the operated feeder,which can ensure the simulation accuracy and reduce modeling complexity and improve the calculation efficiency.Finally,the paper proposes a methods to isolate faults nearby and improve the thermal capacity of VT to effectively improve the fault condition of VT high voltage fuse blown.

关 键 词：配电网 电磁式电压互感器 熔丝故障 低频振荡 单相接地故障 

分 类 号：TM74[电气工程—电力系统及自动化]