1 距离保护（ZM1-5）1 情况 概述距离保护装置是在输电网和变电网中应用得最广泛的一种保护装置。在配电网中它也变得越来越重要。主要原因如下：*它在线路两端之间的通信通道中的独立性，是因为它是利用本地有效电流和电压信息动作的。*距离保护在电力网中形成了一个相互关联的有选择性的保护系统（非单元式的保护系统）。这意味着它也可以作为网络中其他主要元件的远后备保护。现代线路保护的基本要求，比如快速性，灵敏性和选择性，以及在可靠性和安全性方面的严格要求，变得越来越严格。另外，现代距离保护在网络中必须能够与阻抗继电器配合动作，这是一种由不同技术设计而成的继电器（静态或者是机电式继电器）。较早的阻抗继电器在多数情况下只用于电力线路的相间和三相故障的保护，一些其他保护用于接地故障中。由于这些原因现代距离保护的灵活性非常重要，当它用于一个复杂的网络结构时尤其合适。比如并列运行的多回线路和辐射网。距离保护的有选择性动作不是依靠线路两端间的通信设备。距离保护能在远方末端电流互感器处检测到故障。这个功能使它成为那些不能检测到超过反方向末端电流互感器范围以外故障的线路差动保护的一个理想补偿。距离保护范围在线路REX 5XX的保护、控制和终端监测方面的距离保护装置由3到5个独立的距离保护范围组成，每一个包括了3个接地故障的测量元件和3个相间故障的测量元件。对于各种不同电压等级在不同的电网中，不同的终端要适合不同的要求。由于这个原因，距离保护装置的一些特征参数各终端之间是不同的（要了解详细内容，请查阅线路保护终端的分类细节）。距离保护区域5不同于其他段在于它动作的快速性。它比其他距离保护段启动快，而且在不同的系统暂态过程中，由于这个原因误动的可能性就更高了，因此它只适用于以下情况：允许更高越限或者作为具有超过100ms延时的延时距离保护段。线路差动保护的补充在一些线路差动保护终端设备中（如REL 561）距离保护装置能够成为一个有选择性的保护。同时它是超出反方向末端电流互感器以外故障时的主保护，这个功能由带延时段实现（如II段），它覆盖了所有相邻母线，因此形成了母线的主保护或后备保护。所以超越段应处于持续动作状态。保护范围为部分线路的保护段（如I段）可以作为线路差动保护的后备。只要差动保护动作这个功能就不需要了。为了减小I段误动的风险，可以在差动保护拒动时将其投入，差动保护失灵的最大原因就是通信系统故障。由于这个原因用于距离保护的通信方案应该使用另一个通信途径而舍弃用于线路差动保护的那一个方案。简单参数的整定每一距离保护段基本上包含了作为相对地、相间测量的完全独立的整定参数。这是复杂网络结构中和那些被要求使新配置的距离保护装置适应目前其他类型继电器的网络的一个优势情况。一套简明的可选择参数适用于反映各种类型故障的相同最大保护范围是一个标准惯例的场合。参看整定参数和整定操作说明表格。基本特性作为合成到线路REX 5XX保护终端的距离保护装置是一个全方案的距离保护。这意味着在不同范围内对于各种类型故障它都有单独的测量元件。根据终端类型，它至少由5个独立的阻抗测量范围（详情参看通信规则详文）组成，每一个都是四边形特性，示例插图如图38。RL和XL代表线路电阻和电抗，RF代表保护范围的电阻最大值。A2 Line impedanceAbout this chapterThis chapter describes the line impedance functions in the 1 Distance protection (ZM1-5)1 ApplicationGeneralThe distance protection function is the most widely spread protection function in transmission and subtransmission It is also becoming increasingly important indistribution The main reasons for this are:• Its independence on communication links between the line ends， because for its operation，it uses information about the locally available currents and • The distance protection forms a relatively selective protection system (non-unit protectionsystem) in the power This means that it can also operate as a remoteback-up protection for other primary elements in the The basic requirements for modern line protection， such as speed， sensitivity and selectivity， with their strict requirements for dependability and security (availability)， aregetting more In addition， modern distance protections must be able to operate in networks with existing distance relays， which are mostly designed in a different technology (static or even electromechanical relays)Older distance relays protect in many cases power lines only at phase-to-phase and three-phase Some other protection is used for phase-to-earth The flexibility of modern distance protection is for this reason very This especially applies when it is used in a complex network configuration， for example， on parallel operating multicircuit lines and on multiterminal The selective operation of the distance protection does not depend on communication facilities between two line At the same time， the distance protection can detect faults beyond the current transformers at the remote This functionality makes it an ideal complement to the line differential protection function that cannot detect faults beyond the current transformer at the opposite Distance protection zonesThe distance protection function in REx 5xx line protection， control， and monitoring terminals consists of three to five independent distance protection zones， each of them comprising three measuring elements for phase-to-earth (Ph-E) faults and/or three measuring elements for phase-to-phase (Ph-PH) Different terminals suit different requirements in different networks on various voltage For this reason， some characteristic parameters of the distance protection function differ from terminal to For detailed information， please refer to ordering particulars for each line protection terminal REx 5xx Distance protection zone five differs from other zones with respect to its speed of It starts faster than other distance protection zones and might have for this reason higher overreaching for different system It is for this reason suggested to use it only for the applications， which permit higher overreaching， ( switch-onto-fault function) or as a time delayed distance protection zone with time delay longer than 100 Complement to the line differential protectionThe distance protection function can become optional protection in some line differential protection terminals (REL 561， for example) At the same time it represents the primary protection for faults beyond the current transformers at the opposite This functionality is achieved by the time delayed overreaching zone (generally zone 2)， which covers at least the adjacent busbar and thus forms a primary or back-up protectionfor the So the overreaching zone should be continuously in An underreaching zone (generally zone 1) can form a back-up to the line differential There is no need for this function as long as the differential protection is in To minimize the risk of unwanted operation from zone 1， this function can be activated only when the differential function is out of The most likelycause to lose the differential protection is a failure within the communication The communication scheme used with the distance protection should for this reason use another communication channel than the one used by the line differential Set of simplified setting parametersEach distance protection zone comprises basically completely independent setting parameters for phase-to-earth， and for phase-to-phase This is an application advantage in complex network configurations and in networks， where it is required to adjust the newly applied distance protection functions to the existing other types of relays (overcurrent earth fault， for example)A set of simplified optional parameters is available optionally for applications， where equal zone reaches for all kinds of faults are a standard See the table of setting parameters and the setting Line impedanceBasic characteristicsThe distance protection function， as built into the REx 5xx line protection terminals， is a full-scheme distance This means that it has individual measuring elements for different types of faults within different Depending on the type of terminal， it consists of up to five (for details see the corresponding ordering details) independent， impedance-measuring zones， each has a quadrilateral characteristic， as symbolically illustrated in figure RL and XL represent line resistance and reactance and RF represents the resistive reach of a protective
