【作者】 苏明；

【导师】 李永丽；

【作者基本信息】 天津大学 ， 电力系统及其自动化， 2007， 硕士

【摘要】 2005年9月26日,我国电压等级最高的网络——西北750kV青海官亭至甘肃兰州东输变电示范工程正式投入运行,这项工程的完成标志着我国电力工业发展水平的飞跃,也为将来实现1000kV输电打下了基础。由于超、特高压输电线路是联接大电网或远距离输电网的骨架,因此对继电保护的性能要求很高。在各种线路保护原理中,分相电流纵联差动保护是理想的保护方式。其具有绝对的选择性,不受振荡的影响,不受运行方式的影响,受过渡电阻的影响小,本身具有选相功能。另外随着电力光纤网的普及和光纤通信技术的成熟,光纤分相电流纵联差动保护已成为超高压及特高压输电线路保护首选的保护原理。为了使特高压长线路上的分相电流差动保护能够可靠动作,需要补偿电容电流。而精确的线路参数是准确的电容电流补偿的关键。特高压输电线路的参数一般是通过离线计算或现场实测获得,但在运行过程中往往还要受到沿线地质、气候、大地电阻率分布不均等因素的影响,特别是在恶劣的高寒地带,当线路被冰雪覆盖时,将会使线路参数明显偏离给定值。本文提出了一种利用牛拉法在线估算线路参数的算法,仿真试验表明该算法能够精确的估算出线路带与不带并联电抗器情况下的正序和零序参数。另外,本文对基于瞬时值和相量的分相电流差动保护原理进行了分析比较,给出了这两种保护原理的实现方法,并利用EMTDC仿真软件比较了它们在不同运行情况下的优缺点,最后提出了将两种保护原理综合使用的方案。更多还原

【Abstract】 On Sept. 26^th 2005, the national transmission line with highest voltage, whichstarts from Guanting Qinghai Province to Lanzhou Shanxi Province with its voltageclass up to 750 kV, was bringed to service formally. It is a tremendous achievementfor the development of the national power industry. The EHV or UHV transmissionline is the framework to link power transmission system or to link remote powertransmissionsystem. Thereforeit is veryimportant toimprovethequalityoftherelayprotectionforit.The Segregated Current Differential Protection is an ideal protection principle,which has many advantages such as its absolute selectivity, its bearing effect ofvibration of power system and so on. As the popularization of optical fiber grid andthe optical commumication being matured, the Segregated Current DifferentialProtection will have been the preferred longitudinal protection for the EHV or UHVtransmissionline.Distributed capacitance current of EHV or UHV transmission line is always amajor factor to effect the quality of the Segregated Current Differential Protection.And getting the accurate line parameters is the key to compensate the capacitancecurrent exactly. The line parameters of UHV transmission line are obtained fromoff-line calculation or actual measurement. But because of the capricious location,climate and resistivity of land, especially in the abominoable paramos thetransmission line with cryoconite cover, the line parameters derive from the settingvalue obviously. The paper gives the Newton-Raphson method to estimate the lineparameter on-line, and the emulation and analysis demonstrates that it can completeon-line parameters estimation accurately for transmission line with shunt reactor ornone.In addition, the paper analyses the two methods of Segregated CurrentDifferential Protection: the method of instantaneous value and the method of phasor,the implementation approach of which are also given. And with the software ofEMTDC, the merits and drawbacks of the two methods will be compared in thevarious operational aspects. Finally, a programme which can integraed reuse the twomethodswillbegiven.更多还原