特高压输电技术具有输送容量大、损耗低、占地面积省等优势，与我国用电需求量大、资源分布不均的国情相适应，因而我国大力建设特高压输电系统势在必行。但电网电压等级的提高也对设备绝缘提出了更高的要求，1000kV电力设备制造难度大、所需成本也更高，故研究1000kV交流系统工频过电压与操作过电压及其抑制措施意义重大。 本文以1000kV单回、双回线路的工频过电压与操作过电压为研究对象，考虑了可能出现过电压问题的多种运行方式以及双回线路严重的电磁耦合，建立了1000kV单回输电系统和双回输电系统的ATP-EMTP模型。详细分析了工频过电压、操作过电压的发生条件和产生机理，计算了系统可能出现的工频过电压、操作过电压，并根据线路工频过电压、操作过电压的影响因素，给出了过电压的抑制措施，研究了高压并联电抗器、耦合地线、断路器并联电阻、避雷器等设备对线路过电压的影响并进行了仿真验证。 通过理论分析和仿真计算，可得出：1000kV交流线路供电距离较长，在线路中适当分段运行有利于限制过电压；长度小于100km的1000kV线路可以不装设高压并联电抗器，此时系统工频过电压可以控制在1.4p.u.以内；1000kV线路最大工频过电压由单相接地甩负荷过电压决定、最大操作过电压由合闸过电压和故障激发过电压决定；通过装设并联电抗器、低残压金属氧化物避雷器、良导体地线、低阻值并联电阻，可以将线路操作过电压限制到1.6p.u.以下。上述结论具有较高的工程参考价值。

UHV transmission technology has the advantage of large transmission power, low losses, and less line corridor, which is suitable for China's power industry conditions of large electricity demand and uneven resources distribution. Therefore, it is imperative to build UHV transmission system. However, the increase of grid voltage brings not only longer transmission distance and greater capacity, but also higher requirements of equipment insulation. Considering that the 1000kV power equipment is difficult to manufacture and cost too much, it is of great significance to study the characteristics and control measures of the power frequency overvoltage and switching overvoltage of 1000kV system. This thesis took power frequency overvoltage and switching overvoltage of 1000kV single-circuit transmission systems and double-circuit transmission systems as the research object, considering kinds of operation modes in which overvoltage problems may occured and electromagnetic coupling of double-circuit transmission systems, the ATP-EMTP model of 1000kV single-circuit and double-circuit transmission systems is established. This paper analyzes the generation condition and mechanism of power frequency overvoltage and switching overvoltage. Then, the power frequency overvoltage and switching overvoltage was calculated, and some restraining measures of overvoltage was given according to the influence factors of power frequency overvoltage and switching overvoltage. The influence of shunt reactors, ground wires, parallel resistance, arrester and other devices on line overvoltage is studied and verified by simulation. Through the theoretical analysis and simulation calculation of this paper, it is believed that suitable segmenting operation in the line is conducive to limiting overvoltage because of the 1000kV line has a long power supply distance. A 1000kV line which is less than 100km may not be equipped with shunt reactor, because of the power frequency overvoltage energy in this condition can be controlled within 1.4p.u. The maximum power frequency overvoltage is determined by single-phase grounding unload overvoltage, and the maximum switching overvoltage is determined by the switching operate and the fault excitation overvoltage. By installing the shunt reactor, low residual voltage MOA, good conductor ground wire and small parallel resistor, the line operation can be limited under 1.6p.u.. Those above conclusions are valuable in the engineering.