1、http:/ http:/ and suppression measures of transformer magnetizing inrush current generation摘要：变压器作为交流电力系统重要的电气设备，其正常运行直接关系着系统的安全。差动保护作为变压器主保护，励磁涌流是影响其正确动作与否的关键因素之一。文章分析了变压器励磁涌流及其特点，以单相变压器为例，分析了励磁涌流产生的机理，并给出了常见的抑制措施。Abstract: transformer as AC power system electrical equipment important, its normal o
2、peration is directly related to the safety of the system. Differential protection as the main protection of transformer, inrush current is one of the key factors and its action is right or not. This paper analyzes the inrush current and its characteristics, taking single-phase transformer as an exam
3、ple, the mechanism of inrush current generated by the analysis, and gives the measures to suppress the common.关键词：变压器 励磁涌流 二次谐波 间断角Keywords: transformer inrush current harmonic two interval angle1、变压器励磁涌流及特点1, transformer inrush current and the characteristics of变压器是一种依据电磁感应原理制造而成的静止元件，是交流输电系统中用于电压变
4、换的重要电气设备。当合上断路器给变压器充电时，有时候，能够观察到变压器电流表的指针有很大摆动，随后，很快又返回到正常的空载电流值，这个冲击电流通常就被称为励磁涌流。The static components of transformer is a basis of electromagnetic induction principle, manufacture, is an important electrical equipment voltage converter for AC transmission system. When the circuit breaker to the tr
5、ansformer when charging, sometimes, can observe the pointer to the transformer current meter has a great swing, then, quickly returned to normal values of no-load current, the current impact is often referred to as the inrush current.总的来说，变压器励磁涌流有以下几个特点：第一，波形呈现尖顶形状，表明其中含有相当成分的非周期分量和高次谐波分量，其中高次谐波以二次和
6、三次为主，并且，随着http:/ http:/ 120 度相位差，所以涌流也不尽相同。第三，在最初几个波形中，涌流将出现间断角。第四，涌流衰减的时间常数与变压器阻抗、容量和铁心材料等都相关。In general, the transformer magnetizing inrush current has the following characteristics: first, waveform showing spire shape, show that the aperiodic component and harmonic component which contains a comp
7、onent, wherein the harmonic in two and three, and, with time, a phase two harmonic content may exceed the fundamental component more than half. Second, excitation inrush current amplitude and the initial phase angle of no-load transformer is directly related to. For single-phase transformer, when th
8、e voltage over zero input, inrush current maximum amplitude. Because each phase of three-phase transformer with 120 phase difference, so the inrush current are not the same. Third, in the first few waveform, current will appear discontinuous angle. Fourth, the current decay time constant and impedan
9、ce of transformer, capacity and core materials are related.2、励磁涌流产生机理2, the generation mechanism of inrush current变压器励磁涌流是由变压器铁心饱和引起的。在铁心不饱和时，铁心磁化曲线的斜率很大，励磁电流近似为零；一旦铁心出现饱和，磁化曲线斜率变小，电流随着磁通线性增长，最终演变为励磁涌流。Transformer inrush current is caused by the transformer core saturation. In the core is not satura
10、ted, core magnetization curve slope is large, the excitation current is approximately zero; once the core saturation magnetization curve slope, smaller, current with flux linear growth, eventually evolved into the inrush current.下面以单相变压器空载合闸为例分析励磁涌流产生机理。设变压器在时间 t=0 时合闸，则施加于变压器上的电压为：The following to
11、single-phase transformer no-load closing to the producing mechanism of inrush current cases. The transformer is provided on at time t=0, the voltage applied to the transformer for:（1）http:/ http:/ （2）Also, the relationship between the transformer voltage and flux for: ( 2 )故： （3）Therefore: ( 3 )式（3）
12、中第一式为稳态磁通，后两式为暂态磁通，为铁心剩磁，与合闸时刻的电压相关。Type (3 ) in the first type is a steady-state flux, two for the transient flux, as the core remanence, voltage associated with closing time.计及成本和工艺，现代常用的电力变压器饱和磁通一般设为 1.151.4，而变压器运行电压一般不应超过额定电压的 10%。因此，变压器稳态正常运行时，磁通不会超过饱和磁通，铁心也不会饱和。但在暂态过程中，如变压器空载合闸时，由于剩磁的作用，运行磁通就有
13、可能大于饱和磁通，从而造成变压器饱和。例如，最严重的是电压过零时刻，合闸，假若此时铁心的剩磁，非周期磁通为经过半个周期后，磁通达到，将远大于饱和磁通，造成变压器严重饱和。Considering cost and process, commonly used in modern power transformer saturation flux is generally set to 1.15 1.4, and the transformer voltage generally should not exceed 10% of rated voltage. Therefore, the 3D s
14、teady during normal operation, the magnetic flux does not exceed the saturation magnetic flux, the core is not saturated. But in the transient process, such as the transformer no-load closing, the remanence effect, there may be greater than the operating flux saturation flux, resulting in transforme
15、r saturation. For example, the most serious is the voltage zero-crossing moment, closing, remanence if core, aperiodic flux after half a cycle, the flux reached, will be greater than the saturation magnetic flux, the transformer saturation.3、抑制措施3, control measures对于现场中常用的三相电力变压器，防止变压器励磁涌流引起差动保护的措施主
16、要有以下几类。For three-phase power transformer used in the field, to prevent the differential protection of transformer magnetizing inrush current caused by the measures mainly in the following categories.3.1 采用速饱和中间变流器http:/ http:/ the velocity saturation intermediate converter差动保护按照躲开最大不平衡电流进行整定时，带速饱和原理
17、的差动保护能够减少非周期分量造成的保护误动，如 BCH-2 型就是一种增强型速饱和中间变流器的差动保护。这种差动保护的核心部分是带短路线圈的饱和中间变流器和差动电流继电器。短路线圈的存在使得在具有非周期分量电流时继电器的动作电流大为增加，从而提高了躲避励磁涌流和外部短路时暂态不平衡电流的性能。采用 BCH-2 型差动保护要注意短路线圈匝数的确定匝数愈多躲避涌流的性能愈好，但内部短路时继电器的动作延时就长。对中小型变压器，由于励磁涌流倍数大，内部故障时非周期分量衰减快，对保护动作要求又较低，一般选较大的匝数，而对大型变压器，内部涌流倍数小，非周期分量衰减慢，又要求保护动作快，则应选较小的匝数。最
18、后选用的抽头是否合适，应经变压器空投试验来确定。同时，灵敏度检验应按内部短路时最小短路电流来进行。如不满足要求，则应选带制动特性的差动保护。与 BCH-2 型原理相同的还有 DCD-2 型差动继电器构成的差动保护。Differential protection to avoid the maximum unbalanced current for the entire time, belt velocity saturation of differential protection principle to protection misoperation caused by aperiodic
19、 component, differential protection such as type BCH-2 is an enhanced velocity saturation intermediate converter. The core part of the differential protection is short-circuited coil saturated intermediate converters and current differential relay. Short circuit coil makes the action current relay w
20、ith current aperiodic component is greatly increased, thereby improving performance to avoid the inrush current and external short circuit transient unbalanced current. Using BCH-2 differential protection should pay attention to performance is better turns more to avoid the inrush current to determi
21、ne the short-circuit coil turn number, but the time-delay of internal short circuit when the relay is long. For medium and small transformer magnetizing inrush current, because of times, the internal fault of non fast decaying periodic component, on protection requirements is relatively low, general
22、ly choose larger numbers of turns, but for large transformer inrush current, internal multiple small, damping non-periodic components and slow, fast protection action, it should be a small number of turns. The final selection of the tap is appropriate, shall be approved by the transformer airdrop te
23、st to determine. At the same time, sensitivity test should be the minimum short-circuit current internal short circuit to. If not meet the requirements, differential protection should be selected with the brake characteristics. Differential protection with the same type BCH-2 principle and DCD-2 typ
24、e differential relay.http:/ http:/ In general, the belt speed saturation principle of longitudinal differential protection for large operating current, low sensitivity, and the transformer internal fault, the aperiodic component and delay action, has been eliminated gradually.3.2 二次谐波制动3.2 two harmo
25、nic brake依照励磁涌流中含有二次谐波的特点，设计了二次谐波制动的方法，一旦保护检测到差流中含有的二次谐波大于保护整定值，就闭锁保护继电器，防止励磁涌流引起保护动作。二次谐波制动的动作判据可写为： （4）In accordance with the inrush current contains two harmonic characteristics, design of the two harmonic braking method, two harmonic of differential current protection detection once contained gr
26、eater than the setting values of protection, blocking protection relay, to prevent inrush current caused by the action of protection. The two criterion of harmonic brake can be written as: ( 4 )其中，和分别为差流中的基波和二次谐波分量的幅值，为二次谐波制动比。现场应用时，根据运行经验和空载合闸试验，一般按照躲过各种励磁涌流下，最小的二次谐波含量整定。一般而言，二次谐波制动比可设为（15%，20% ） 。
27、Among them, and for differential current of the fundamental and two harmonic amplitude, two harmonic brake ratio. Application of the site, according to the operation experience and no-load test, general according to avoid the various magnetizing inrush current, the two harmonic content of the smalle
28、st setting. Generally speaking, the two harmonic brake ratio ( 15%, 20% ).二次谐波制动的差动保护原理简单，调试简便，灵敏度高，在当前变压器纵差保护中应用广泛。但是，在安装有静止无功补偿装置等电容分量比较大的系统，故障暂态电流中也有较大的二次谐波含量，致使差动保护动作速度受到影响。若空载合闸前变压器已经存在故障，合闸后故障相为故障电流，非故障相为励磁涌流，采用三相或门制动的方案时，差动保护必将被闭锁。由于励磁涌流衰减很慢，保护的动作时间可能会长达数百毫秒。这也是二次谐波制动方法的主要缺点。The two different
29、ial protection principle of harmonic brake is simple, convenient debugging, high sensitivity, wide application in current transformer longitudinal differential protection. However, http:/ http:/ the installation of a static idle compensation device system capacitance of relatively large, the fault t
30、ransient current two times in the harmonic content is larger, the movement speed of differential protection is influenced by. If the no-load closing of transformer has fault, after closing the fault phase fault current, fault phase as the excitation inrush current, three-phase or brake scheme, the d
31、ifferential protection will be locked. Because the inrush current decay very slowly, the protection action time may be up to hundreds of milliseconds. The main drawback of this is the two time harmonic restraint method.3.3 间断角鉴别的方法Methods 3.3 dead angle identification前面提到，在最初几个波形中，涌流将出现间断角。而变压器内部故障时
32、流入差动继电器的稳态差电流是正弦波，不会出现间断角。间断角鉴别的方法就是利用这个特征鉴别励磁涌流和故障电流，即通过检测差电流波形是否存在间断角，当间断角大于整定值时将差动保护闭锁。间断角制动的保护整定值一般设为 65。对于 Y/d 接线方式的三相变压器，非对称涌流的间断角比较大，间断角闭锁元件能够可靠的动作，并且裕量充足；而对称性涌流的间断角会小于 65。进一步减小整定值并不是好的方法，因为整定值太小会影响内部故障时的灵敏度和动作速度。由于对称性涌流的波宽等于 120，而故障电流（正弦波）的波宽为 180，因此在间断角判据的基础上再增加一个反应波宽的辅助判据，在波宽大于140（有 20的裕量）
33、时也将差动保护闭锁。间断角原理由于采用按相闭锁的方法，在变压器合闸于内部故障时，能够快速动作。这一点是比二次谐波制动（三相或门制动）方法优越的地方。对于大型变压器，可以同时采用两种原理的纵差动保护，能够起到优势互补，加快内部故障的动作速度，不失为一种好的配置方案。As mentioned earlier, in the first few waveform, current will appear discontinuous angle. The steady state and the transformer internal fault into the differential rela
34、y differential current is sine wave, no dead angle. Method of intermittent fillet identification is to use this feature to identify inrush current and fault current, namely, by detecting the current existence of discontinuous angle, when the dead angle is larger than the setting value will be lockin
35、g differential protection. Protection of intermittent fillet brake setting value is set to 65 degrees. Three-phase transformer with Y/d connection mode, intermittent asymmetrical inrush current angle is large, the intermittent angle locking element can be reliable action, and ample margin; and inter
36、mittent fillet symmetrical inrush current will be less than 65 . To further reduce the tuning is not good method and value, http:/ http:/ the setting value is too small to affect the internal fault sensitivity and speed of action. Due to the wave width symmetrical inrush current and fault current is
37、 equal to 120, ( sine wave ) wave width is 180, the dead angle criterion to increase aid criterion with a width of more than 140 degrees in the reaction wave, wave width ( margin with 20 ) will also be locking differential protection. The intermission angle principle adopts the method according to t
38、he phase locking, the transformer internal fault closing in, quick action. This is more than two times harmonic brake ( three-phase or braking ) local excellent method. For large transformer longitudinal differential protection, can adopt two kinds of principle, can play a complementary advantages,
39、operation speed internal fault, is a good scheme.参考文献Reference1王维俭.电气主设备继电保护原理与运行M. 北京：中国电力出版社， 1996.1 Wang Weijian electric main equipment relay protection principle and operation of M. Beijing: China Electric Power Press, 19962王维俭，候炳蕴.大型机组继电保护理论基础M. 北京：中国电力出版社， 1989.2 Wang Weijian, Hou Bing-yun. Large unit is the basic theory of relay protection M. Beijing: China Electric Power Press, 1989
