1、附录 附录 1 中文译文 线路故障与距离保护 线路故障 由于输电线路是曝露在阳光中并受大气损害 ,输电线路上的故障要比设备上的故障发生的频繁。输电线路故障被列出，按严重程度分为以下几种： （ 1）带或不带故障阻抗的三相故障或三相接地短路故障。最严重但最不普通的这种故障以数量仅仅是一种。 （ 2）带或不带故障阻抗的两相短路接地故障。这种故障比三相故障严重性小，但是普通性大。然而，这种故障以数量是三种。 （ 3）相间短路故障。这种故障比以上故障普通性大，但是严重性小。这种故障以数量也是三种。 （ 4）单相接地故障。这种故障是严重性最小的，但是最普通的一种。这种故障以数量也是三种。 从以上来看，我们
2、得出结论：有四种故障类型，以数量是十种。象三相故障或三相接地短路故障，包括两或多相的两相短路接地故障和相间短路故障，这三种故障被认为是相故障，即，单相接地故障被叫做接地故障。所有线路故障将把系统带入不正常的 运行状态，并且很可能损害电气设备。因此，故障线必须通过保护继电器从系统中切除。 距离保护 当故障发生在电力传输线上时，保护系统需要切除故障输电线路。为了确保可靠并且快速的切除故障线路，具有不同原理的几种保护系统经常用来保护一条线路。在它们之间，距离保护对于电力传输线是最重要的一种保护。 距离保护的操作依靠下列事实 ,一旦故障发生 ,在电力系统和故障任何点之间的距离与这点电压对电流的比成比例
3、。在相互连接的网络中 ,那可能有许多电站 ,在电站电压电流比是最大值 ,并且减小不同提供者到故障那几乎是零。对电压电流比作出响应的 继电器被用在电力系统不同的点来给出到故障的距离的测量或线路的长度。通过安装继电器，因此离故障最近的比远点的运行比较快，控制不同供者的有区别的短路器已应用。通常，三段式距离保护被用在传输线的保护。 标准的三段式保护 普通的距离继电器用三段测量元件（各自元件或者带有时间元件来增加前者范围的第一和第二段的一元件，对于第三段的第二元件）。第一段的元件被设置覆盖第一部分的 80%到 90%，是一个瞬间高速继电器，然而覆盖地二部分的大约25%第二段的元件和覆盖第二部分末端的第
4、三段元件是延时继电器。第二和第三段的时间继电器 T2、 T3 由各自的时间继电器提供。安置小于长度 100%的第一段用来避免继电器伸得过长到一个部分。伸得过长由以下原因发生：暂态越过继电器，继电器上的毛病，电流互感器和电压互感器的错误，阻抗安置的数据错误被造成。 第二段的元件主要是给第一部分的末端提供保护并且也给下一段达到长度25%远后备。由于它可能操作第一部分末端的灭弧故障是合适的。由于中间电流注入源和上面提及的其他误差的影响，继电器保护区域缩短的可能性也应该被考虑。第二部分元件的时间继电器（ T2）几乎在 0.2 到 0.5 秒之间。 第三段元件给临近线路部分 的故障提供后备保护。在达不到
5、最大范围的情况下它的伸长尽可能的超过最大临近线路部分的末端。第三段时间继电器（ T3）通常在 0.4 到 1.0 秒之间。 在许多情况下，例如连贯的线路部分以长度不同，以上方案的代替物，许多的步或者时间继电器，可能需要最优的选择和保护。 三段式保护方案由图 1 给出。 附图 1 三段式保护图 距离保护的要求 距离继电器有三个基本特征是必须的。它们是：方向的响应，阻抗的响应，时间。这些特征不是必须有各自的继电元件提供，但是对于所有的距离方案来说它们基本的。就方向和测量继电器而言，在任何方案被要求的实际数量在三相系统中是被影响的，三相故障、相间故障、相对地的故障、两相对地故障必须被顾及。 因此，对
6、于提供两个距离继电器各自的装置来说是普通的实践，一个相故障的装置和一个对地故障的装置。在它们之间这些满足三相故障和两相对地故障。这些继电器的每一套包括三个分部继电器（一个是每两相的相故障和一个是每相对地故障）。对于比 较早被描述的三段式每一个继电器由 2 或 3 个元件组成。因此距离保护方案通过许多必须的继电器是不可避免的复杂。这些有时减少使用简单的继电器对于许多任务（开关距离方案），但是象这过分的结合包含选择电路并且导致延时操作。相距离方案已经不带任何开关的被发展。 附录 2 英文原文 Faults on Transmission Lines and Distance Protection
7、Faults on Transmission Lines Because transmission lines are exposed to lightning and other atmospheric hazards, faults on them occur more frequently than those in apparatus. The types of faults taking place on a transmission line are listed, in the order of severity, as following: (1) fault (LLL fau
8、lt) or to ground fault (LLLG fault) with or without fault impedance. This fault which is most severe but least common is only one in number. (2) Double line to ground (LLG) fault with or without fault impedance. This fault is less severe but more common than fault. However, this type of faults is th
9、ree in number. (3) Line to line (LL) fault. This fault is more common but less severe than the above fault. These faults are also three in number. (4) Single line to ground (LG) fault. This fault is the least severe but the most common one. These faults are also three in number. From the above, we c
10、onclude that there are four types of faults which are ten in number. The first three faults such as LLL or LLLG, LLG and LL faults involving two or more phases are known as phase fault while the fourth fault, namely, LG fault, is called ground fault. All of the line faults will bring the system into
11、 abnormal operating conditions, and may damage electrical equipment. Therefore, the faulty lines must be isolated from the system by protection relays. Distance Protection When faults occur on a power transmission line, a protection system is required to isolate the faulted transmission line. To gua
12、rantee reliable and quick isolation of the faulted line, several protection systems with different principles are usually employed to protect one transmission line. Among them, distance protection system is one of the most important protections applied for transmission lines. The operation of distan
13、ce protection depends on the basic fact that on the occurrence of a fault, the distance between any point in the power system and the fault is proportional to the ratio of voltage to current at the point. In an interconnected network in which there may be a number of power stations, the voltage to c
14、urrent ratio is a maximum at the power station and decreases along the various feeders to the fault where it is almost zero. Relays responding to this voltage/current ratio can therefore be used at various points on the system to give a measure of the distance or length of the line to the fault. By
15、arranging the relays such that those nearest to the fault operate quicker than those at a farther distance, discriminative tripping of the circuit breakers controlling the various feeders can be obtained. Usually, a 3-zone distance protection schemes is employed for transmission line protection. Sta
16、ndard 3-zone Protection The conventional distance relaying uses three distance measuring units (physically separate units or one unit for first and second zones with a timing unit to increase the reach of the former and a second unit for the third zone). The first zone unit which is set to cover usually between 80% and 90% of the first section, is an instantaneous high speed relay while the second zone unit which is set to cover about 3 33
