基于坡印亭矢量的输电导线无功功率计算及影响因素分析

发布时间：2018-04-29 08:44

  本文选题：输电线 + 覆冰　； 参考：《重庆大学》2014年硕士论文

【摘要】：随着我国用电负荷不断增长，高电压等级的地下电力电缆以及特高压输电线路的建设在过去几年快速推进。高电压等级输电线路因其输电距离长、输送容量大，因此交流高压输电线路的无功功率的补偿对线路的稳定运行有着重要的意义。当架空输电导线覆冰、地下电力电缆隧道环境遭受破坏时，输电线路的等效电参数将会改变，，在计算分析输电线路的无功功率时需要考虑输电线路电参数的改变。 对于正常运行输电线路，常常采用“路”的方法计算输电线路的传输功率。当输电导线覆冰、地下电力电缆隧道环境遭受破坏时，由于输电线路的等效电参数改变，从“路”的角度计算传输功率的复杂度将提高。 因此论文提出了基于坡印亭矢量的输电线能量传输表征模型，即从“场”的角度计算输电线路的传输功率。首先推导了坡印廷矢量表征电磁能量的数值表达式，进而基于空间步进FDFD法提出了输电线三维能量传输表征模型，模型中提出了带状电荷模型计算输电线路的初始截面电场强度。基于FDFD的三维传输能量表征模型能够计算不规则覆冰架空输电线、不规范敷设的电缆的功率传输情况。 本文运用基于坡印亭矢量的输电线能量传输表征模型计算了架空输电线弧垂及覆冰情况，电缆输电线介质分层情况、偏心情况、电缆沟积水情况的功率传输情况。计算结果表明： （1）弧垂导致输电线容性无功和感性无功损耗都增加。弧垂最低点处截面，单位长度空间容性无功损耗有较大的增加，感性无功损耗略微减小；导线悬挂点处，单位长度容性和感性无功损耗略微增加。 （2）输电线容性功率损耗随覆冰厚度增加而增加，在相同覆冰厚度下不同覆冰形状的容性无功损耗规律为：圆形椭圆新月形，椭圆≈偏心椭圆翼型。具有覆冰越不规则，则容性无功损耗越高的特点。 （3）对于单端接地电缆，电缆隧道积水导致容性无功增加率达到49.89%。在偏心位移为1~2.5mm的区间，电缆容性无功增量随偏心位移增加呈二次函数关系递增。 根据输电线下方不同环境温湿度下的定点测量电场值，拟合分析了空气相对介电系数与环境温湿度的关系。基于坡印亭矢量的输电线能量传输表征模型计算了环境温湿度对输电线能量损耗的影响，并从能量的角度反推了不同环境温湿度下输电线等效电路参数。
[Abstract]:With the increasing of power load in China, the construction of high voltage underground power cable and UHV transmission line has been advancing rapidly in the past few years. Because of its long transmission distance and large transmission capacity, the reactive power compensation of high voltage transmission line is of great significance to the stable operation of the transmission line. When overhead transmission lines are covered with ice and the environment of underground power cable tunnels is damaged, the equivalent electrical parameters of transmission lines will change, and the change of electrical parameters of transmission lines should be considered in the calculation and analysis of reactive power of transmission lines. For the normal operation of transmission lines, the transmission power of transmission lines is often calculated by the method of "path". When the transmission line is covered with ice and the environment of underground power cable tunnel is destroyed, the complexity of calculating transmission power from the angle of "path" will be increased because of the change of equivalent electrical parameters of transmission line. Therefore, this paper presents a representation model of transmission line energy transmission based on Poynting vector, that is, calculating the transmission power of transmission line from the angle of "field". In this paper, the numerical expression of electromagnetic energy representation by Poynting vector is first derived, and then a three-dimensional energy transmission representation model for transmission lines is proposed based on the spatial step FDFD method. In the model, a band charge model is proposed to calculate the initial cross-section electric field intensity of transmission lines. The three-dimensional transmission energy representation model based on FDFD can calculate the power transmission of irregular ice-covered overhead transmission lines and non-standard laid cables. In this paper, the energy transmission characterization model of transmission line based on Poynting vector is used to calculate the power transmission of overhead transmission lines, such as sag and icing, dielectric stratification, eccentricity and water accumulation in cable trenches. The results show that: Sag can increase capacitive reactive power and inductive reactive power loss. In the section at the lowest point of sag, the capacitive reactive power loss per unit length increases greatly, the inductive reactive power loss decreases slightly, and the unit length capacitive and inductive reactive power loss increases slightly at the traverse suspension point. (2) the capacitive power loss of transmission lines increases with the increase of icing thickness. The law of capacitive reactive power loss for different icing shapes under the same ice thickness is as follows: circular elliptic crescent, ellipse 鈮

本文编号：1819219