【作者】 李博通；

【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】 电力系统的运行经验表明,架空线路的故障大都是“瞬时性”的,因此,作为保证电力系统可靠供电和安全运行的重要措施之一,自动重合闸技术在电力系统架空线路中普遍应用。但是常规自动重合闸装置一般不具备识别瞬时性故障和永久性故障的能力,其重合带有一定的盲目性,当重合于永久性故障时,会对系统造成严重的危害。如果能够在重合之前预先判断故障性质(瞬时故障或永久故障),实现装置的自适应动作,则可避免重合于永久性故障,减少对系统的冲击,增强系统的稳定性。作为当前理想的重合方式,自适应自动重合闸受到国内外学者的广泛关注。本文首先介绍了已有的电压判据的原理、适用范围以及存在的缺陷等问题。在此基础上,提出了故障点电压判据,其原理为首先应用故障线路的双端电气量以及故障测距结果,求得故障点的电压,然后与整定值进行比较来识别瞬时性故障还是永久性故障。由于瞬时性故障时故障点电压会远大于永久性故障时故障点电压,因此,此方法具有准确判定故障性质的能力,且不受过渡电阻和线路长度的影响。超高压输电线路上普遍应用并联电抗器,由于并联电抗器对线路电容的补偿作用会影响自适应重合闸功能的实现,本文阐述了并联电抗器及中性点小电抗的参数选择原则和取值范围并分析了并联电抗器参数变化对恢复电压的影响。带并联电抗器线路中发生单相瞬时性故障时断开相的恢复电压中除工频分量外,还产生了一个低频衰减周期分量,其叠加效果为“拍”特性。本文基于复频域分析方法对恢复电压的暂态特性进行了理论推导,并进行了PSCAD仿真验证。通过与永久性故障时的恢复电压进行比较,提出了判定永久性故障和瞬时性故障的低频电压幅值判据。为从端电压中获取低频衰减周期分量,本文用相差为半工频周期整数倍的端电压瞬时值做差(和)来消去工频分量,再去求低频衰减周期分量的幅值。更多还原

【Abstract】 Operation experiences of power system shows that the faults occurred onoverhead lines are mostly transient. So automatic reclosure is widely used intransmission lines as one of the important methods for improving secure and reliableoperation of power system. But conventional autoreclosure’s shortcoming is that itacts blindly entirely before reclosing and can’t distinguish transient fault frompermanent fault. It will cause serious damage to power system. If fault could bejudged advanced before the operation of reclosure, That is to say, the reclosure couldoperation adaptively according to the characteristic of the fault, power system couldkeep working stable because of the avoidance of reclosing on permanent fault and thesubsequent impact on system.Firstly, the paper analyses the voltage algorithm of single-pole adaptive reclosure,and presents its theory, applying range and disadvantages. Then an new approachbased on the voltage at fault point to distinguish between transient and permanentfault in single pole reclosure is brought forward. Using electric data from both side oftransmission line and fault location, fault point voltage can obtained and comparedwith setting value. Because the magnitude of it is far big when transient fault happensthan that when permanent fault happens, this approach is able to work exactly andwon’t be affected by transition resistance and length of the line.Compensation for capacitance along the transmission line by Shunt reactorswhich is used universally on EHV and UHV would have some effect on the operationof reclosure, so the rule of how to select the value of shunt reactors and neutralgrounding reactor, which exert an influence on recovery voltage, is introduced. Thereis a decaying periodic component besides the power frequency voltage and thenestification of them is beating wave, when single-pole transient fault happens ontransmission line with shunt reactors. The components of recovery voltage areanalyzed by complex frequency-domain analysis and emulate by PSCAD. A criterionfor distinguishing between transient and permanent fault is presented by measuringthe decaying periodic component of recovery voltage. A new algorithm is developedfor getting the magnitude of decaying periodic component of recovery voltage.更多还原