±800kV特高压直流输电线路单极接地故障过电压产生机理及影响因素

Overvoltage generation mechanism during single-pole grounding fault of ±800 kV UHVDC transmission lines and its influencing factors

将特高压直流输电线路单极接地故障过电压分成第一次跃升和第二次跃升2个过程,并基于极线间的电磁耦合作用和波过程阐述了2次电压跃升的产生机理;分析了直流滤波器主电容、直流滤波器型式、直流控制系统、杆塔接地电阻、线路中点杆塔是否装设避雷器、输电线路参数和输送功率等多种因素对该过电压的影响。仿真结果表明,直流滤波器主电容参数是限制单极接地故障过电压的关键因素,其他因素对该过电压影响不大,为控制过电压幅值不超过额定电压的1.7倍,建议±800 k V特高压线路的直流滤波器主电容参数取值范围为1-2μF。

The overvoltage process of single-pole grounding fault of UHVDC transmission line is divided into two parts：the first voltage jump and the second voltage jump. The generation mechanism of two voltage jumps is studied based on the electromagnetic coupling between two poles and the wave process. The influences of different factors on the overvoltage are analyzed,such as main DC filter capacitor,DC filter type,DC control system,grounding resistance of line tower,arrester installed on tower at line midpoint,transmission line parameters,transferring power,etc. Simulative results show that,the main capacitor of DC filter is a critical factor to limit the overvoltage while the others have little effect on the overvoltage. Recommended capacitance of the main capacitor of DC filter for ±800 k V UHVDC lines is from 1 μF to 2 μF for limiting the overvoltage within 1.7 times of rated voltage.