短距离不换位同塔多回输电线路不平衡分析

Unbalance Analysis of Short Distance Non-transposed Multi-circuit Transmission Lines on the Same Tower

衡量短距离不换位同塔多回输电线路三相不平衡度需要准确测量正弦稳态下正序、负序和零序电流,这在潮流不断变化且电磁耦合复杂的实际线路中是很难实现的。为此,引入概率统计中衡量数据离散度的变异系数来衡量输电线路的三相不平衡度,直接计算线路阻抗的变异系数,计算简单、准确。同时,考虑架空地线、大地电阻、无功补偿装置和串联电抗器对线路阻抗的影响,基于输电线路分布参数模型,建立了短距离不换位同塔多回输电线路的分析模型。分析了计算江西某220 kV实际双回输电线路。结果表明,线路电流计算结果与实测值误差小于1%,并提出了该线路不平衡度最小的相序排列方式为ABC-CBA。为减小短距离不换位同塔多回输电线路的不平衡度提供了理论参考。

To measure the three-phase unbalance degree of short-distance non-transposed multi-circuit transmission lines on the same tower,it is necessary to accurately measure the positive sequence,negative sequence and zero-sequence currents in sinusoidal steady state,which is difficult to achieve in the actual lines with changing power flow and complex electromagnetic coupling.To this end,the coefficient of variation for measuring the data dispersion in probability statistics was introduced to measure the three-phase unbalance of the transmission line,and the coefficient of variation of the line impedance was directly calculated.In this way,the calculation was simple and accurate.At the same time,considering the influence of overhead ground wire,earth resistance,reactive power compensation device and series reactor on the line impedance,based on the distribution parameter model of the transmission line,an analytical model for short-distance non-transposed multi-circuit transmission lines on the same tower was established.A 220 kV actual double-circuit transmission line in Jiangxi was analysed and caculated.The results show that the error between the calculated results of the line current and the measured value is less than 1%,and the phase sequence arrangement mode with the minimum unbalance degree of the line is suggested as ABC-CBA,which provides a theoretical reference for reducing the unbalance degree of the short-distance non-transposed multi circuit transmission line on the same tower.