微机母线保护原理毕业论文译文.doc

微机母线保护原理摘要：母线保护是当母线发生故障时，迅速切除故障母线的主要保护，根据母线保护构成的原理不同，母线保护可以分为好几种类型。随着科技的不断发展，微机母线保护也被大量应用，其种类越来越多，但是其应用的主要原理还是没有太多的变化，大多还是采用完全电流差动原理构成的母线差动保护。微机母线保护其特点是对不同的一次主接线方式的适应性比较强，在一次运行方式变化时，其差动回路和出口回路有比较科学、合理的方法来跟随一次作相应的调整，本文就母线保护的构成原理和微机母线保护所采用的原理进行简要的阐述，对微机母线保护在不同的主接线方式中的应用进行了详细的应用分析。1概述1.1母线保护的一般分类根据母线差动保护的差动回路构成方式不同，母线保护可分为母线完全差动保护和母线不完全差动保护。由于差动回路构成方式的不一样，各自的特点也不尽相同，其适用范围也有所不同，一般情况下：对于中性点直接接地的电网中，常用母线完全差动保护，而对于中性点非直接接地的电网，则采用母线不完全差动保护。1.2母线完全差动保护的原理母线完全差动保护是将母线上所有连接元件上的电流互感器按同名相、同极性连接到差动回路中，其中电流互感器的极性与变比均应相同，如果变比不同时，可以采用补偿变流器进行补偿。这样，在一次侧电流总和为零的情况下，理论上，二次侧电流的总和也应为零，在电流互感器的二次绕组在在母线侧的端子互相连接在一起，线路侧端子互相连接在一起，然后通过差动继电器线圈连接构成差动回路.当正常和区外故障时，我们可以把母线看成一个节点，根据基尔霍夫定律可知，流入母线与流出母线的一次电流之和为零，即而流入差动继电器的电流为所以差动继电器不会工作。当区外故障时，所有电源的线路都向故障点提供故障电流。从图1可知为故障点的总故障电流，亦是差动电流，差动继电器动作从而跳开母线上所有断路器。在实际的现场中，由于各组电流互感器特性不可能完全一样，所以就必然存在一定的不平衡电流。1.3母线不完全差动保护的原理母线不完全差动保护是将有电源的元件上装设特性和变比完全相同的D级电流互感器，只在发电机变压器、分段断路器（母联断路器）上装设电流互感器，且电流互感器只装设在A、C两相上。电路互感器二次绕组母线侧端子互相连接，线路侧端子互相连接，与差动继电器线圈连接组成二次电流差动回路。当正常运行时，由电厂发出的电流为，由于引出线XL1和XL2均没有电流互感器，所以在正常运行时，差动继电器电流为，即差动继电器电流等于没有装设电流互感器的所以元件负荷电流的总和。如果保护的动作值大于此电流值，则差动继电器不会动作。当区内故障时，全部电流流向故障点。由图2可以看出，此时流入差动继电器的电流为全部的短路电流，这个电流值很大，保护装置就能够很灵敏地动作。1.4根据母线差动保护的判椐不同分类根据母线差动保护判据的不同，母线差动保护又可以分为由电流差动原理构成的母线差动保护、母联电流相位比较原理构成的母线差动保护、电流相位比较原理构成的母线差动保护。1.5电流差动原理构成的母线差动保护对于电流差动原理构成的母线保护而言，它是通过判断母线上各支路电流电流矢量和是否为零或各有源支路的电流矢量和是否大于一定的值来判断母线是否故障。1.6母联电流相位比较式母线差动保护母联电流相位比较式母线差动保护主要是在母联断路器上使用比较两电流相量的方向元件，引入的一个电流量是母线上各连接元件电流的相量和即差流，引入的另一个电流量是流过母联断路器的电流，在正常运行和区外短路是差流很小，方向元件不动作。当母线故障时，不仅差流很大且母联断路器的故障电流由非故障母线流向故障母线，具有方向性。因此方向元件动作且有选择故障母线的能力，当母联断路器断开时，将失去方向性。1.7电流相位比较式母线保护电流相位比较式母线保护是根据母线外部故障或内部故障是连接在改母线上各元件电流相位变化来实现的。当线路正常运行或外部故障是，电流流入母线的电流与流出母线的电流大小相等、方向相反，而当母线上故障时，电流都流向母线。在理想情况下，各支路电流的相位相同。显然，利用比较元件比较各元件电流相位，便可以判断母线是内部故障还是外部故障，从而确定保护的动作情况。2.微机母线保护常用的原理在现阶段，微机母线保护的应用比较广泛，其保护原理大多也采用完全电流差动原理构成母线保护，采用这一原理的主要原因在于由电流差动原理构成的母线保护，在不同的母线接线方式下或电网运行方式变化时，以及发生故障的类型、故障点过渡电阻等方面都具有较强的适应性，区外故障时能可靠不动作，区内故障时能可靠动作。从微机母线保护的现场实际运行情况来看，这些优点也得到了很好的验证和体现。3主接线方式的不同对微机母线保护的影响3.1主接线方式的不同对差动回路的影响由于微机母线保护大多采用的是完全电源差动原理，所以差动回路与一次主接线方式密切相关。当一次主接线方式不同或者一次运行方式变化时，差动回路亦跟随一次方式变化而作相应的调整。根据完全差动原理，无论是一次系统如何变化，正常运行时，其一次电流对母线来说都是平衡的，所以二次差动回路在一次接线方式不同时或一次运行方式变化时，也要作相应的调整才能正确反映一次系统的电流平衡情况。在微机母线保护中，为了达到这一要求，通常是采用刀闸位置来判断本单元处在哪一母线，从而将电流归算到相应的差动回路中。对于特殊的接线方式和特殊单元（如旁路、母联等）采取特殊的约定，从而实现母线差动回路能够正确反映不同接线方式母线二次电流情况，为母线保护的正确判断提供可靠依据。3.2主接线方式的不同对出口回路的影响主接线方式的不同以及一次运行方式的变化对出口回路的影响，相对来说比较小，对于一般的出线，可以通过刀闸位置的判断来决定本支路属于那条母线，其出口回路是否动作。对于特殊单元（如母联等）可以通过特殊的约定，来决定特殊单元的出口回路是否动作。4微机母线保护在不同主接线方式下实现方案4.1差动回路及出口逻辑表示方法的假设在微机母线保护差动回路的计算和出口回路的动作逻辑都与刀闸位置有着密切关系，为了下面表述的方便，我们用表示N单元母刀闸位置，用表示N单元母刀闸位置，其值为0或1（0表示刀闸分，1表示刀闸合），用表示母联的运行状态，其值为0或1（0表示母联分，1表示母联合），用表示N单元的电流数字量，表示母联的电流数字量，表示N单元的动作情况（0表示动作，1表示不动作）。、分别表示母和母的故障情况（0表示不故障，1表示故障），出线单元在这里我们把它都看成可倒单元。4.2双母线接线方式双母线接线方式是比较常见的一次接线方式。也是一种比较典型的一次接线方式。在微机母线保护中，对正常的出线单元通过刀闸辅助接点的判断来确定本单元的电流处于哪一差动回路，出口回路也是通过刀闸辅助接点来判断是否处在故障母线。在双母线中，母联是特殊单元，通过对母联电流互感器的极性的特殊约定，母联可以作为母的单元也可以作为母的单元。假定母联极性与母单元极性相同，我们可以通过一定的表达式来表示电流回路电流和出口回路的动作逻辑。5结束语从以上对微机母线保护的差动回路和出口动作逻辑回路的分析，我们可以看出：其构成原理比较简洁、科学合理，实施起来比较方便，对交流量的采集比较精确，实际应用起来也比较灵活。但是对刀闸位置接点的采集要求比较高，刀闸位置接点采集的正确与否关系到保护装置能不能对一次接线方式、一次运行方式的正确判断，关系到电流差动回路的组成。所以，对现场工作的人员来说，对闸刀位置接点采集回路要特别重视，对回路的可靠性要有保证，并要通过操作一次设备进行正确性验证。各单元的极性要正确，特别是母联等特殊单元的极性要根据保护装置的要求来接线，同时对电流差动回路的接地要完全按照规程和反措的要求来实施。对于到高压开关场地的电缆，电缆两端的屏蔽层要按规程要求进行接地。相对于电磁型母差保护而言，在一次运行方式变化时，运行人员对微机母差保护的操作大大将少，但在刀闸位置变化时，运行人员必需对保护装置反映刀闸位置的情况进行核对，以便能够在有异常情况时能及时发现，更早地对异常情况进行处理。 THE BUSBAR PROTECTION PRINCIPLEBusbar protection is when a failure occurs when bus, quickly cut off the straps of the principal protection, in accordance with a principle protection bus, bus protection can be divided into several types. As technology continues to evolve as the personal computer bus protection has also been a number of applications, and its increasing variety, but the application of the principle of whether or not they have too many changes, mostly or entirely with current differential theory constitutes a busbar differential protection. Micro-machines which are characterized by bus protection for a different time of the main terminal by a strong adaptability, in a run time of the change, the differential circuit and the outlet circuit with a more scientific and rational approach to follow a time adjusted accordingly, this document constitutes a theory of the busbar protection and the protection of the bus with the principles set out in brief, the personal computer bus protection in the main terminal by different applications in a detailed application analysis.1.Outline1.1 General classification of Busbar protectionAccording to differential circuit of Busbar differential protection constitute in different ways, bus-bar protection can be divided into the bus-bar differential protection and completely bus-bar differential protection of incomplete. Because of the differential circuit formation is different, its own characteristics are not the same, its scope varies, generally: for directly grounded neutral power system, fully differential bus protection for neutral point indirectly grounded power system, the bus-bar differential protection of incomplete.1.2 Bus full of differential protection principleBusbar differential protection is completely on a bus on all connected components according to the phase of the same name, the same polarity of current transformer connected to a differential circuit, polarity and current transformer ratio should be the same, if the ratio is not the same as compensation converter can be used to compensate. In this way, in the case of a side currents sum to zero, theoretically, secondary currents sum to zero, the current transformer secondary winding terminals connected together on the bus side, line-side terminals connected together, and then by differential connection constitutes a differential relay coil circuit.When normal and external fault, we can bus as a node, according to Kirchhoff's law shows that the inflow of bus and outflow of the bus current is zero, that is. The inflow of the differential relay current differential relay will not work. When external fault, all power line fault current to the point of failure. Figure 1 shows the point of failure, the total fault current, differential current differential relay to trip all circuit breakers on the bus. In the actual field, due to the current transformer characteristics of each group can not be exactly the same, so there must be a certain imbalance in current.1.3 Principle of incomplete differential bus protectionBus-bar differential protection of incomplete is to have the power of component installation on exactly the same characteristics and ratio of d-class current transformers, in subparagraph generator transformers, circuit breakers (mother breaker) installed on current transformer and current transformer fitted with on the a, c, two-phase. Circuit bus side of transformer's secondary winding terminals connected to each other, line-side terminals connected, connections and differential relay coil current differential circuit for the second time. When functioning, of current emitted by power plants, because the PIN out neither the XL1 and XL2 current transformers, so in normal running, current differential relay, current differential relay without the installation of current transformer component of the sum of load currents.If the protection action value that is greater than the current value, the differential relays are not actions. When a failure in the region, all of the current flow to the point of failure. You can see from Figure 2, into the current differential relay for all of the short circuit current, the current value is large, protective device is sensitive to the action.待添加的隐藏文字内容21.4 Sentence noted in different categories according to the busbar differential protectionAccording to the different bus-bar differential protection criterion, bus-bar differential protection can be divided into the current differential principle structure of Busbar differential protection, consisting of Bus Coupler current phase comparative theory, current phase comparison bus differential protection principle structure of Busbar differential protection.1.5 The current differential principle constitute the busbar differential protectionFor the principle of current differential bus protection of, it is the bus judgment on the bus of each branch current current vector is zero or the current vector of each source slip is greater than a certain value to determine whether the fault. 1.6 The mother of the current phase busbar differential protectionThe mother of the current phase busbar differential protection is mainly used in the bus coupler circuit breaker Comparison of two in the direction of the current phasor components, the introduction of an electric current to each connected component current phasor bus and differential current, the introduction of another amount of current flowing through the bus coupler circuit breaker current, short circuit in normal operation and outside the region is small differential current directional element does not work. When the bus fault is not only poor flow of the great bus coupler circuit breaker fault current flows to the fault bus, bus by a non-fault directional. Directional element in action and the ability to select the fault bus when the bus coupler breaker will lose direction.1.7 The current phase busbar protectionThe current phase busbar protection under the bus external fault or internal fault is connected to changes in the current phase of each component to achieve the reform bus. When the normal operation of the line or external fault current into the bus current and the current size of the outflow of bus equal and opposite, and when the bus failure, the current flow to the bus. Ideally, the phase current of each branch. Obviously, the comparison component compares each component current phase, we can determine that the bus is an internal fault or external fault in order to determine the action of the protection.2. Principle of microcomputer-based bus protectionAt this stage, the application of the busbar protection is more extensive, and most of its protection principles are also adopted fully the current differential principle, busbar protection, the main reason for using this principle is constituted by the principle of current differential bus protection, in a different bus connection mode or operation mode changes, as well as the type of failure, the point of failure transition resistance has strong adaptability to external fault can be reliably does not move, the region of failure can be reliably action. From the practical operation of the busbar protection point of view, these advantages have been well verified and embodied.3. The main effect of connection mode of microcomputer-based bus protection3.1 Main wiring of different effect on the differential circuitSince most microcomputer bus protection using full power differential protection principle, so the differential circuit and is closely related to a main-line. When a main connection in different ways or a running change, differential circuit follows a change and make appropriate adjustments. According to the principle of fully differential, no matter how is a system change, during normal operation, the primary current is balanced on bus, so the differential circuit for the second time in a connection different time or at run time, have to make the appropriate adjustments to correctly reflect the current balance of a system. Microcomputer-based bus protection, in order to meet this requirement, often switch location to determine the cell in which a bus, so that the current reduction in the appropriate differential circuit. For connection and special units of the special (such as bypass, the mother) of special conventions, so as to achieve the bus-bar differential circuit to correctly reflect the different connection modes of Busbar secondary current situation, provide a reliable basis for bus-bar protection right.3.2 The main wiring of different effects on export loopThe main wiring way different as well as a movement way change to exports the return route the influence, quite is on the other hand small, regarding the general going beyond a line, may through the knife switch position judgment decide this leg belongs to that generatrix, whether its exportation return route does act.(Stepmother unites and so on) regarding the special unit to be possible through the special agreement, decided special unit exportation return route whether acts. 4. Different main wiring in microcomputer-based bus protection in implementation 4.1 Differential circuit and export a logical representation of the assumptionIn computer bus protection difference dynamic circuit of calculation and export circuit of action logic are and knife gate location has close relationship, to following description of easy, we with said n unit mother knife gate location, with said n unit mother knife gate location, its value for 0 or 1 (0 said knife gate min, 1 said knife gate-in), with said mother joint of run State, its value for 0 or 1 (0 said mother joint min, 1 said mother joint), with said n unit of current digital volume, said mother joint of current digital volume, N units of action (0, 1 for no action) . And represent the failure of and (0 indicates no failure, 1 indicates failure), the outlet unit where we take it all as a unit.4.2 Double Busbar connectionDouble bus connection is one of the more common connection. A connection is a typical. In microcomputer-based bus protection in the normal outlet unit by switch auxiliary contacts of judgment to determine the unit of electric current in which differential circuit, exit circuits is switch auxiliary contacts to determine if bus at fault. In double bus, Bus Coupler is a special unit, through the Bus Coupler current transformer polarity of special conventions, as a mother I unit can also be used as units of II. Assumes same polarity as the cell polarity, we can be represented by certain expressions and current loop current export action logic circuit.5.Concluding remarksFrom above on the differential circuit of microcomputer-based bus protection and export operation logic circuit analysis, we can see that its constituent principles more concise, scientific and rational, easier to implement, communication acquisition more precise, practical applications and more flexible. But to switch locations contact acquisition requirements is relatively high, knife gate location contact collection can correct or not related to the protection of connection mode, run once on a right of way, on the composition of the differential current circuit. So, for personnel working on the scene, knife collection circuit should pay special attention to contacts, reliabil