一种新型的同塔双回输电线路工频阻抗参数测量方法

基于输电线路三相不平衡及感应电压干扰在短时间不变的前提,提出了一种新型的同塔双回输电线路工频阻抗参数测量方法。该方法采用单相电源多变换接入的方式对不对称线路进行分相解耦测量,通过建立数学模型、数据拟合和矩阵变换,从而获得单回或两回线路的序阻抗及各序之间的耦合阻抗。该方法克服了高感应电压及三相不平衡对线路参数测试的影响,具有简单、精确、稳定等特点,测试结果表明了本文方法的有效性。     

风偏角与杆塔结构对500kV同杆双回线路绕击耐雷性能的影响

分析500kV双回输电线路的绕击耐雷性能,对EGM进行了改进。在计算过程中为考虑风的影响,引入风偏角;同时引入了雷击避雷线与雷击地面击穿强度比值随杆塔高度h变化的系数β。用暴露弧法计算每根导线绕击跳闸率,以暴露弧为0时对应的雷电流作为雷电的最大绕击电流,并分析了风偏角、杆塔结构等因素对500kV双回输电线路各导线绕击跳闸率的影响。结果表明,风偏角增大,绕击跳闸率增大;总绕击跳闸率随避雷线横担增长而减小;各导线绕击跳闸率与杆塔结构间的关系复杂,需具体计算分析。理论分析和计算验证了该方法的实用性和有效性,具有一定的工程指导意义。     

500 kV同杆双回线路雷电反击性能的研究

利用Bergeron特征线法,编程对同杆双回交流500kV输电线路的反击耐雷性能进行了详细的计算和分析,考了雷击塔顶时导线上交流工频电压的随机性,利用统计法确定超高压线路的反击耐雷性能。并分析了接地电阻对同杆双回线路耐雷水平的影响。     

Research on the electric unbalance degree of multiple transmission lines non-parallelly erected entirely in one common corridor

When multiple transmission lines are not entirely parallel erected in one common corridor, the electric unbalance degree of double-circuit ultra-high voltage (UHV) AC transmission line can be affected by several factors, such as severe electromagnetic coupling between lines in parallel section, various phase sequence arrangements and transposing modes of the lines, active power of the lines changing constantly. This paper presents a detailed analysis on the electric unbalance degree of double-circuit UHV AC line in common corridor, with particular attention to the effects of the parallel section’s length, number and the active power of the lines. The causes and factors of unbalanced currents of double-circuit UHV AC line were taken into account by phase-sequence conversion of current and voltage, and the above effects were proved by an actual example. The main factors were studied by simulating in PSCAD/EMTDC. The results show that the parallel section’s length, number and the active power of lines have considerable influences on the electric unbalance degree of double-circuit UHV AC line in common corridor. Finally, some suggestions have been proposed to provide as a construction reference to confine the level of electric unbalance degree of double-circuit UHV AC line which is not entirely parallel erected with other lines in common corridor.     

220kV同塔双回线路雷击双回同跳防雷改造

同塔双回输电线路双回同跳严重威胁电网的安全稳定运行。内蒙古地区包青线220k V同塔双回输电线路发生过2次雷击造成双回同跳事故,本文采用EMTP软件对事故进行仿真复现。仿真计算结果表明:一定幅值的雷电流击中塔顶时,可能造成与现场实际吻合的双回线路C相同跳。通过比较绝缘子串两端雷电过电压中几个分量对最终闪络电压的贡献度得知,220 k V线路工频相位是影响双回输电线路ABC三相闪络顺序的主要原因。降低杆塔冲击接地电阻和安装线路避雷器是提高耐雷水平和降低雷击跳闸率最简单可行的措施。当非全相安装避雷器时,若每回路安装一支避雷器,建议安装在下相;若每回路安装两支避雷器,建议安装在中相和下相。     

500kV线路IVI型双回路直线铁塔的规划设计

为科学规划500kV IVI型双回路直线塔,该文从挂线布置形式、经济档距规划等方面,采用基于数学期望的最优化理论进行最优设计,最终得出该塔型在技术和经济有较大的优势,具有广泛的应用价值。     

特高压双回路GIL感应电压电流计算分析

气体绝缘线路(GIL)回路间电磁感应关系不同于架空导线,线路中存在GIL将会影响感应电压、电流的计算结果,从而影响线路地刀的选型。文中以同塔双回架空线和GIL混合特高压线路为例,研究回路间电磁感应的计算。首先对GIL进行电气参数计算,并理论推导混合线路感应电压、电流计算公式;其次利用EMTP-ATP仿真验证理论分析结果,分别仿真研究了GIL在母线位置、在线路中间以及不含GIL 3种工况下的感应电压、电流变化规律,并分析了GIL在线路中间时感应电流大幅度增加的原因;最后研究了GIL在线路中长度占比的不同对感应电压、电流的影响。研究结果可为含GIL的混合线路地刀选型提供理论计算参考。     

同杆并架双回线路行波传播特性的研究

该文用EMTP仿真研究了同杆并架双回线路上故障产生的行波特点及其传播规律：同杆并架双回线路的行波由6个模量构成，各种模量的色散情况相差较大：故障产生行波的色散较单回线路复杂；行波色散是造成故障测距误差大的重要原因：利用行波故障定位时要考虑采用多相行波数据。该文的研究结果对充分利用行波特点来进行行波保护和故障测距有非常重要的参考和实用价值。     

A fast time–frequency transform based differential relaying scheme for UPFC based double-circuit transmission line

This paper presents a new differential relaying scheme for a mutually coupled, double circuit transmission line in presence of Unified Power Flow Controller (UPFC) in the line. The process starts at retrieving the three phase current signals at both ends of the transmission line synchronously and processing it though the time–frequency transform such as Fast Discrete S-Transform to derive the spectral energy content of the current signals. The differential spectral energy of current signals (difference between the spectral energy of the current signal at the sending and receiving ends, respectively) of the respective phases of transmission line is used to register the fault pattern. The proposed approach includes fault detection and classification along with identification of the fault section with respect to UPFC location in one of the double-circuit transmission line. The extensive test results indicate that the proposed differential relaying scheme is highly reliable in registering fault patterns in UPFC based transmission line including wide variations in operating parameters of the power network.     

A functional auxiliary module for 1st-zone conventional distance relays of double-circuit lines to eliminate high fault resistance-introduced under-reach

This paper presents design steps of an auxiliary module intended to function in conjunction with under-operation 1st-zone conventional distance relays of double-circuit transmission lines. The proposed module pursues the objective of eliminating the underreach of associated ground elements, arising from single-line-to-ground faults of high resistance. It is founded on the online estimation of the fault distance during the faults, through the roots of a non-linear algebraic equation developed in the sequence networks. The equation is mathematically discussed and a fitting numerical algorithm efficiently finding its roots with no concern about the computation burden is chosen. In order to be applicable to the lines of any lengths, particularly long lines, the proposed module is developed through the distributed-parameter based model of double-circuit lines. In addition, it employs only the data acquired at the relaying location and is independent of the network configuration. Important considerations are made for the proposed module, making its function both dependable and secure. Simulation studies conducted in MATLAB and PSCAD/EMTDC examine the proposed module in a variety of influencing situations, and confirm that it accurately fulfills its intended objective within the time frame of the distance protection.