1、http:/ http:/ excitation inrush current mechanism and suppression measures to explore contrast in both Chinese and English 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 an important of communicatio
2、n power system electrical equipment, the normal operation of the system has a close relationship with safety. Differential protection for transformer main protection, excitation inrush current is one of the key factors affecting the correct operation or not. Excitation inrush current of transformer
3、is analyzed and its characteristics of a single-phase transformer as an example, analyzed the mechanism of excitation inrush current, and the inhibition of common measures is given. 关键词：变压器 励磁涌流 二次谐波 间断角Keywords: transformer excitation inrush current second harmonic discontinuous Angle 1、变压器励磁涌流及特点1
4、, transformer excitation inrush current and the characteristic 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。Transformer is a kind of based on electromagnetic induction principle and static element, is used in ac transmission s
5、ystem voltage transformation of the important electrical equipment. When close the circuit breaker to charging transformer, sometimes, can be observed in transformer ammeter pointer has great swing, then quickly return to normal no-load current value, the impact current is usually referred to as the
6、 excitation 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。Transformer excitation inrush current, on the whole, have the following characteristics: first, the waveform in spire shape, that it contains quite th
7、e aperiodic component and high harmonic components, the high harmonics is given priority to with two times and three times, and, over time, the second harmonic content could be more than one phase of the fundamental component for more than half. Second, excitation inrush current amplitude is directl
8、y related to early transformer no-load input voltage phase Angle. For single-phase transformer, when a zero input voltage, excitation inrush current amplitude is the largest. Due to three-phase transformer and the 120 degree phase difference, so the flow also is not the same. Third, in the first few
9、 waveform, the flow will appear discontinuous Angle. Fourth, the inrush current decay time constant and transformer impedance, capacity and core materials are related. 2、励磁涌流产生机理2, the mechanism of excitation 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
10、长，最终演变为励磁涌流。Transformer excitation inrush current is caused by the transformer core saturation. Unsaturated in core, core slope of the curve is very big, exciting current approximate to zero; Once the iron core saturation, magnetization curve slope decreases and current with magnetic flux linear gro
11、wth, eventually evolved into excitation 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 excitation inrush current in single-phase transformer no-load closing, for example analysis mechanism. A transformer at time t equals zero switching, is applied to the voltage in transfo
12、rmer is: http:/ http:/ 又，变压器电压与磁通间的关系为： （2）Again, the voltage transformer with magnetic: on the relationship between (2) 故： （3）Reason: (3) 式（3）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) the first type is the steady state flux, after two type for transient magnetic flux, as the core remanence, asso
13、ciated with the voltage of switching 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。Plan and cost and technology, modern commonly us
14、ed power transformer saturation magnetic flux generally set at 1.15 1.15, and the transformer operating voltage in general should not exceed 10% of the rated voltage. Steady state when the normal operation of the transformer magnetic flux, therefore, will not exceed saturated magnetic flux, the iron
15、 core is not saturated. But in the transient process, such as transformer no-load closing, as a result of the action of remanent magnetism, operation flux is likely greater than the saturation magnetic flux, resulting in saturation of transformer. , for example, is the most severe voltage zero point
16、, switch, if the core remanence, aperiodic flux for after half a cycle, the flux reached, will be greater than the saturation magnetic flux, causing serious saturation transformer. 3、抑制措施3, inhibiting 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要有以下几类。For the scene that is commonly used in three-pha
17、se power transformer, the measures to prevent http:/ http:/ transformer excitation inrush current differential protection caused by basically has the following categories. 3.1 采用速饱和中间变流器3.1 USES the velocity saturation current transformer in the middle 差动保护按照躲开最大不平衡电流进行整定时，带速饱和原理的差动保护能够减少非周期分量造成的保护误
18、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。最后选用的抽头是否合适，应经变压器空投试验
19、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。According to dodge the maximum unbalance current differential protection for the whole time, tape speed saturation of the principle of differential protection can reduce the protection misoperation caused by aperi
20、odic component, such as BCH - type 2 is a kind of enhanced velocity saturation of current transformer differential protection. Is the core part of the differential protection with short-circuit coil saturation of current transformer and current differential relay. The existence of the short-circuit
21、coil of bring up the aperiodic component in current relay action current increase greatly, thus improve the escape excitation inrush current and external short circuit transient unbalanced current performance. The BCH - type 2 short-circuit coil number of turns of the differential protection should
22、pay attention to determine the number of turns more to avoid the flow performance is better, but the action of internal short circuit relay time delay is long. Multiples of medium and small transformer, due to the excitation inrush current, internal fault when the aperiodic component attenuation fas
23、t, to protect the movement request again low, generally choose the larger number of turns, and for large transformer, the internal flow ratio is small, aperiodic component attenuation slower, demanding fast again, choose the smaller number of turns. Finally choose tap is appropriate, should be throu
24、gh transformer drop test to determine. http:/ http:/ the same time, the minimum sensitivity test should be according to the internal short circuit when the short circuit current. If do not meet the requirements, the persons to braking characteristics of the differential protection. With BCH - type 2
25、 same principle and DCD - type 2 differential relay consists of the differential protection. 总的来说，带速饱和原理的纵差保护由于动作电流大，灵敏度低，并且在变压器内部故障时，会由于非周期分量的存在而延迟动作，已逐步被淘汰。Tape speed, on the whole, saturation of the principle of differential protection, because of the large current action sensitivity is low, and
26、the transformer internal fault, due to the existence of the aperiodic component and delay action, has gradually be eliminated. 3.2 二次谐波制动3.2, second harmonic 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）According to the characteristics of exci
27、tation inrush current contains the second harmonic, design the method of second harmonic brake, once the differential current protection detected contains the second harmonic is greater than the protection setting value, latching relay protection, prevent the excitation inrush current caused by prot
28、ection action. Second harmonic braking action criterion 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% ） 。Respectively and the difference in the flow is one of the fundamental and second harmonic components of the amplitu
29、de, as the second harmonic braking ratio. Field application, according to the operation experience and no-load switching-in test, generally according to avoid all kinds of excitation inrush current, setting minimum second harmonic content. In general, second harmonic brake than can be set to (15%, 2
30、0%). 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http:/ http:/ harmonic brake differential protection principle is simple, convenient debug, high sensitivity, wide application in the current transformer differential protection. H
31、owever, static reactive power compensation devices are installed in the capacitance component, such as larger systems, fault transient current, also has a large second harmonic content in the differential protection tripping speed is affected. If no-load switching transformer has existed before the
32、fault, the fault is the fault current, after closing the non-fault phase of excitation inrush current, three-phase or door brake, differential protection will be locked. Due to the excitation inrush current decay is slow, protecting movement time may be up to hundreds of milliseconds. This is the ma
33、in drawback of second harmonic braking method. 3.3 间断角鉴别的方法3.3 continuous Angle identification method 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
34、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）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。Mentioned earlier, in the first fe
35、w waveform, the flow will appear discontinuous Angle. And the transformer internal fault into the differential relay of differential current is sine wave, wont appear discontinuous Angle. Continuous Angle identification method is to use this feature to identify excitation inrush current and fault cu
36、rrent, by testing whether there is a discontinuous http:/ http:/ current waveform Angle, when intermittent Angle is greater than the setting value of the differential protection atresia. Continuous Angle of brake protection setting value is generally set to 65 . For Y/d connection mode of the three-
37、phase transformer, asymmetric flow discontinuous Angle is large, continuous Angle closure components can reliable action, and sufficient margin; And symmetry of flow discontinuity will less than 65 Angle. To further reduce the setting value is not a good method, because the setting value is too smal
38、l will affect the internal fault of sensitivity and speed of action. Flow due to the symmetry of wave width is equal to 120 , and the fault current (sinusoidal) pulse width is 180 , thus the continuous Angle criterion on the basis of adding auxiliary criterion a wide response wave, wave wide in 140
39、(20 allowance) will also be differential protection atresia. Continuous Angle principle because use according to the phase locking method, the switching transformer internal fault, quickly action. This is better than second harmonic brake braking (three-phase or door) method is superior. For large t
40、ransformer, can adopt two kinds of principle of longitudinal differential protection at the same time, can have complementary advantages, to speed up the action of internal fault, can yet be regarded as a good configuration scheme. 参考文献references 1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.Wang Weijian 1. The main electrical equipment relay protection principle and the operation M. Beijing: China electric power press, 1996. 2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, HouBing aggregates. Large unit relay protection theory M. Beijing: China electric power press, 1989.
