EFFECT OF ADAPTIVE SINGLE-POLE RECLOSING ON TURBINE-GENERATOR SHAFT TORSIONAL TORQUES

ABSTRACT

This paper presents the adaptive reclosing technique as a new concept to reduce the high torsional torques to which the turbine-generator shafts might be subjected during unsuccessful single-pole reclosing. In this context, investigations have been conducted on a detailed benchmark model of a one-machine infinite bus system. The results of these investigations have shown that the high torsional torques induced in the turbine-generator shafts during unsuccessful single-pole reclosing could be avoided by applying the adaptive reclosing technique     

Impact of six phase transmission line faults on turbine-generatorshaft torsional torques

This paper explores the impact of six-phase transmission line faults and their subsequent fault clearing and reclosing on the torsional torques induced in turbine-generator shafts. In this context, investigations have been conducted on a large turbine-generator unit connected to a sample power system. The paper presents also a comparison between the torsional stresses induced in the turbine-generator shafts during these events with their corresponding disturbances of a three-phase transmission system. The results of these investigations are presented in the form of typical time responses as well as parametric studies. The EMTP is used for the simulation studies. The studies conclude that six-phase transmission line faults generally induce torsional torques in the turbine-generator shaft whose magnitudes are relatively higher than those induced due to transmission line faults in a three-phase system. This conclusion is true for both sustained faults and faults followed by clearing and high-speed reclosing operations     

发电厂送出端采用高速重合闸影响的分析研究

本文在开发使用ＢＰＡ－ＥＭＴＰ的基础上，研究了发电厂送出线上采用高速重合闸对汽轮发电组轴系扭振和电力系统运行稳定性的影响。指出对于永久性故障的重合可能导致轴系扭力矩的放大和发电机摇摆角的增大，且与重合时刻有关。文中同时提出了对三相重合闸分组重合的方法。采用这种方法，当重合于永久故障时，可有效降低轴系扭力矩，并能改善机组与电网间的运行稳定性。     

Effect of sequential reclosure of multi-phase system faults onturbine-generator shaft torsional torques

The authors present a method of reducing the high torsional torques induced in turbine-generator shafts during high-speed reclosure of multiphase system faults. The method is based on the sequential reclosing of the faulted circuit. In this context, investigations have been conducted on two turbine-generator units of different designs for various multiphase system faults. The results of both the three-phase-to-ground and double-line-to-ground faults are reported, and the effectiveness of the method is illustrated through parametric studies and simulation results. The effects of the reclosing time and the fault incidence instant on the effectiveness of the method have also been investigated     

一二次配合的配电线路自适应重合闸

针对配电线路常规重合闸因重合前不能区分永久性和瞬时性故障可能造成多次短路冲击的问题,系统论述了基于一二次配合的配电线路自适应重合闸技术。介绍了基于一二次配合的配电线路自适应重合闸4种实现途径,即：限流试探法、电容放电试探法、脉冲试探法和载波试探法。分别论述了限流试探法串联型和并联型两种结构的工作原理以及技术特点,并给出限流阻抗典型参数。理论分析了电容试探法的回路放电特性及阻容参数的选取原则并给出了典型取值。指出脉冲试探法的关键在于分相快速开关的分闸速度和动作离散度,并建议了脉冲试探法下的阻抗参数识别方法实现原理。给出了载波试探法的信号频率及试探电压的选取原则以及典型值。     

A review of single phase adaptive autoreclosingschemes for EHV transmissionlines

Statistics shows that transients produced by lightning or momentary links with external objects, have produced more than 80% of faults in overhead lines. Reclosing of circuit breaker (CB) after a pre-defined dead time is very common however reclosing onto permanent faults may damage the power system stability and aggravate severe damage to the system. Thus, adaptive single-phase auto-reclosing (ASPAR) based on investigating existing electrical signals has fascinated engineers and researchers. An ASPAR blocks CB reclosing onto permanent faults and allows reclosing permission once secondary arc is quenched. To address the subject, there have been many ASPARs techniques proposed based on the features trapped in a faulty phase. This paper presents a critical survey of adaptive auto-reclosing schemes that have hitherto been applied to EHV transmission lines.     

基于级联全桥型直流断路器的直流配电网自适应重合闸方案

柔性直流配电网是配电系统的重要发展方向,可以采用电缆和架空线2种方式组网。鉴于架空线路瞬时性故障多发的特点,基于架空线的柔性直流配电网应配备有效的自适应重合闸方案,以提高供电可靠性。为实现这一目标,从断路器线路端电压与电流的相位差异特征出发,提出一种基于级联全桥型直流断路器控制的自适应重合闸方案。首先,通过断路器转移支路的主动控制产生一定频率的故障检测电压;进而,根据断路器线路端电压电流在对应频率下相位特征的差异,区分瞬时性和永久性故障,并进一步分析了过渡电阻等因素的影响;最后,利用PSCAD/EMTDC仿真平台搭建了柔性直流配电网模型,验证了所提自适应重合闸方案的可行性和有效性。     

基于缺相耦合电压特性的同杆双回线路非跨线故障综合重合闸策略

常规同杆双回线路重合闸策略由于三相抵消原理,其故障相存在的互感电气量非常小,容易受到线路干扰造成误判,重合于永久性故障。提出了一种适用于接地故障的基于缺相耦合电压特性的故障性质判据及综合重合闸策略,对健全线进行了缺相处理,增大了故障线耦合电气量幅值,并增加了非跨线接地故障性质的识别准确度。为使该策略适用于同杆双回线路相间故障和三相故障性质判别,提出在线路装设接地开关的方案,实现了对非跨线非接地故障的快速准确识别。在PSCAD/EMTDC平台上构建仿真模型,验证了该重合闸策略的可行性。     

带并联电抗器同杆双回输电线路跨线接地故障自适应重合闸策略

针对传统重合闸策略不判定故障性质而盲目重合、重合失败对系统造成二次冲击的问题,提出了基于故障相无功功率的带并联电抗器同杆双回输电线路跨线接地故障自适应重合闸策略.首先,提出了准两相跳闸策略,为跨线接地故障中故障相提供充足耦合电气量.其次,基于故障相在瞬时性故障和永久性故障中无功功率的巨大差异,提出了基于无功功率的跨线接...     

重合时序对交直流混联输电系统暂态稳定裕度的影响

单相重合闸技术可以提高供电可靠性,但合于永久故障时是对系统的又一次冲击,因此研究重合的时序对系统暂态稳定裕度的影响是十分必要的。文中以南方电网2005年丰大运行方式下安顺—天生桥500 kV线路发生单相接地短路为例,在未有效区分永久故障和瞬时故障的前提下,以FASTEST为仿真工具,考查了重合闸时序对系统暂态稳定裕度的影响。仿真研究表明,改变线路两侧轮流投入无压检定的做法,由线路非故障侧投入无压检定首先重合,不仅可以较大幅度地提高系统暂态功角、电压和频率稳定裕度,也可以改善2次切断短路电流的断路器的工作条件。并提出了一种与故障测距算法相结合的在线修正线路两侧投入重合闸顺序的方案,以期减少重合于永久故障时对系统的再次冲击,提高系统的暂态稳定性。     

RBF神经网络式自适应单相重合闸的应用研究

为解决微机式自适应重合闸在判别瞬时性故障和永久性故障存在的缺陷 ,提出一种基于RBF神经网络的智能型单相自动重合闸的方案 ,将RBF神经网络运用于其中 ,建立一个三层前向网络模型。利用EMTP及MATLAB进行大量的仿真试验 ,验证了其可行性 ,克服了自适应单相重合闸的电压判据在判别瞬时性故障与永久性故障时存在的缺陷。     

基于样本熵理论的输电线路单相自适应重合闸研究

为了改善现有自适应重合闸技术在电力系统应用中存在的缺陷与不足,本文利用ATP/EMTP对输电线路进行单相接地故障仿真,并对故障相电压信号进行经验模态分解(EMD)。由于样本熵能够很好地衡量信号信息的丰富程度,故对分解后得到的固有模态函数(IMF)进行样本熵值计算,通过熵值的差异从而判断出故障的瞬时性与永久性,保证在瞬时性故障时能成功实现自适应重合闸。通过大量的线路单相接地故障仿真验证了该方法的有效性和实用性。     

多相补偿阻抗元件的研究与仿真分析

对输电线路距离保护多相补偿阻抗元件的工作原理和工作特点进行详细分析,提出2种多相补偿阻抗元件的判据确定方法.仿真分析结果表明,多相补偿阻抗元件可正确区分保护正向区内、正向区外及反方向故障情况,而且受过渡电阻的影响较小.     

New Digital Algorithm for Adaptive Reclosing Based on the Calculation of the Faulted Phase Voltage Total Harmonic Distortion Factor

This paper presents a new numerical algorithm suitable for determining adaptive dead time, and blocking automatic reclosing during permanent faults on overhead lines. It is based on terminal voltage input data processing. The decision if it is safe or not to reclose is determined by the voltage signal of faulted and tripped line phase using the total harmonic distortion factor calculated by discrete Fourier transform. The algorithm was successfully tested using signals recorded on the real power system. The tests demonstrate the ability of the presented algorithm to determine the secondary arc extinction time and to block unsuccessful automatic reclosing of high-voltage lines with permanent fault     

重合时刻对机组轴系扭振的影响

利用表征重合闸操作影响发电机轴系扭振幅度的等值能量函数,导出了瞬时性故障与永久性故障下重合闸操作对轴系冲击最小的理想重合时刻。在此基础上,给出了能够减小重合操作对严重受扰轴段冲击的重合时刻计算方法及计算步骤。仿真计算验证了文献[1]所提出的模型及该文所确定的优化重合时刻的准确性和计算方法的有效性,为改善实际中重合操作对轴系的冲击奠定了理论基础。     

励磁调节系统对汽轮发电机组轴系扭振的影响

本文研究了瞬态过程中励磁调节系统对汽轮发电机组轴系扭振的影响。以单机300MW汽轮发电机组与无限大电网相连为对象,以电力系统发生单相对地短路、误同期并网以及两相间短路后的重合闸为例,计算分析了励磁系统对汽轮发电机组扭振的作用。     

神经网络在电力系统自适应单相重合闸中的应用

根据现代控制技术中电力系统继电保护的要求 ,把人工神经网络理论应用于自适应单相重合闸中 ,并分析了原理实现的可行性 ,为牵引供电系统中自适应重合闸提供了一条新的思路和途径     

500 kV同杆双回线自适应重合闸方案

500kV同杆双回线在电力系统中具有举足轻重的作用,该项目通过综合两回线信息,将非严重永久故障判据、辅助判据以及按相顺序重合原则完美地结合起来,实现了同杆双回线的自适应重合闸功能,从而最大限度地提高了电力系统的稳定性。目前该项目成套保护装置已通过鉴定,并已推广应用。文章着重介绍了该项目的自适应重合闸的原理及保护配置,并对带并联电抗器的电压判据作了改进。     

同杆平行双回线路按相重合闸新方案

基于按相重合闸的概念,提出了同杆并架平行双回线路按相自动重合闸的新方案。文中首先分析了平行双回线路自动重合闸的特点和不利因素;在此基础上,设计了平行双回线路按相重合闸新方案。新方案根据故障类型的不同采取了不同的跳闸策略,尽可能地保证了双回线故障后能够有一回线继续正常运行;并且给出了重合闸振荡平息后的处理措施。该方案既增强了故障持续期间平行双回线两侧系统之间的联系,又减轻了重合于永久性故障的冲击问题。     

Suppression strategy for the inrush current of a solid-state transformer caused by the reclosing process

The automatic reclosing strategy is an efective measure to improve the reliability of a distribution network. It can quickly clear instantaneous faults in the grid. The traditional transformer has proven to be reliable and robust during the reclosing process. However, the infuence of the reclosing process on the operational characteristics and reliability of solid-state transformers (SST) is still unclear. The reclosing action may generate a huge inrush current, resulting in shutdown and even damage of the SST. To address this problem, this paper proposes an inrush current suppression strategy. First, the operational performance of the SST under a reclosing process is discussed, and the inrush current generation mechanism is analyzed in detail. Then, considering the controllability of distributed generation (DG), a novel DG-supported inrush current suppression strategy is proposed. The suppression ability of the DG on inrush current in diferent initial conditions is analyzed. Finally, the efectiveness of the proposed strategy is verifed by simulation and experiment. These show that the proposed strategy can help to enhance the FRT capability of the SST, as well as support the SST to maintain continuous power supply and physical integrity during grid faults.