CN105137275A

CN105137275A - Synchronous motor rotor winding short circuit fault diagnosis method based on stator current injection

Info

Publication number: CN105137275A
Application number: CN201510477867.0A
Authority: CN
Inventors: 武玉才; 李永刚; 王海蛟
Original assignee: North China Electric Power University
Current assignee: North China Electric Power University
Priority date: 2015-08-06
Filing date: 2015-08-06
Publication date: 2015-12-09
Anticipated expiration: 2035-08-06
Also published as: CN105137275B

Abstract

The invention discloses a method for diagnosing the short-circuit fault of the rotor winding of a synchronous motor based on stator current injection. The electric current forms a pulsating magnetic field inside the generator. Rotate the rotor of the synchronous motor so that the pulsating magnetic field passes through the rotor winding of the synchronous motor vertically; measure the voltage and current of the AC voltage input winding, calculate and measure the AC impedance; calculate the fault criterion value: <maths num="0001"> </maths> If it is greater than the preset threshold, it is determined that the synchronous motor has a rotor winding short-circuit fault. The diagnostic method of the present invention does not need to extract the rotor, which avoids possible deterioration of the vibration state after the rotor is reassembled. Its detection cost is low and the speed is fast, and it has achieved high diagnostic accuracy, and can be widely used in off-line detection of short-circuit faults in rotor windings of synchronous motors.

Description

Synchronous Motor Rotor Winding Short Circuit Fault Diagnosis Method Based on Stator Current Injection

技术领域technical field

本发明涉及一种同步电机转子绕组短路故障诊断方法，尤其是一种基于定子电流注入的同步电机转子绕组短路故障诊断方法，属于发电机技术领域。The invention relates to a method for diagnosing short-circuit faults of rotor windings of synchronous motors, in particular to a method for diagnosing short-circuit faults of rotor windings of synchronous motors based on stator current injection, and belongs to the technical field of generators.

背景技术Background technique

同步电机的转子绕组短路故障一直是困扰工程技术人员的难题，近些年关于同步电机的转子绕组短路故障诊断取得了快速的进展，一些检测方法不断在实际应用中得到完善和发展，帮助运行人员缩短了故障处理时间，降低了机组停运时间。The rotor winding short-circuit fault of synchronous motors has always been a difficult problem for engineers and technicians. In recent years, rapid progress has been made in the diagnosis of rotor winding short-circuit faults of synchronous motors. Some detection methods have been continuously improved and developed in practical applications to help operators. The fault handling time is shortened, and the downtime of the unit is reduced.

目前对转子绕组短路的诊断主要包含离线和在线两种方式，其中在线诊断方式由于可以及时发现故障而被人们推崇，目前在线监测方法主要包括：探测线圈法、励磁电流法、虚功率法、轴电压法等，这些方法各有优势，其中一些方法已经在电力系统中有成熟的应用经验，在抗干扰和提高诊断灵敏性方面各种方法都还有一定的发展空间。转子绕组的离线诊断方法较多，具体包括：空载试验法、短路试验法、开口变压器法、直流电阻法、交流阻抗法、分布电压法、两极电压平衡试验法、RSO法。离线检测方法不能及时发现同步电机的转子绕组短路故障，但是多年来一直被运行、检修人员广泛使用，这是因为：(1)转子绕组短路故障对于同步电机非致命性故障，当发电机出现转子绕组短路故障后，在发电机振动不严重的情况下通常不会选择立即停机检修。(2)离线检测方法在停机状态下完成，可以有效排除各类干扰，其检测可靠性较高。因此，几乎所有的大型同步电机在出现转子绕组短路故障特征后，都要进行相关的离线测试试验，其中，开口变压器法、分布电压法、两极电压平衡试验法等需要抽出转子。众所周知，抽出转子检查故障需要更长的停运时间，经济成本高昂，而且可能出现转子回装后机组振动变差现象，因此，离线检测应尽量避免抽出发电机转子。空载短路试验法、RSO法、直流电阻法及交流阻抗法就属于不需要抽出发电机转子的离线检测方法。空载短路试验法是通过对比发电机空载短路曲线与正常时的偏差判断转子绕组短路故障。RSO方法是根据行波原理在转子绕组的两端分别注入阶跃信号，通过比较反射波信号差异判断转子绕组短路故障。直流电阻法和交流阻抗法是通过测量转子的直、交流阻抗判断是否发生转子绕组短路故障。At present, the diagnosis of rotor winding short circuit mainly includes offline and online methods. The online diagnosis method is highly praised because it can find faults in time. At present, the online monitoring methods mainly include: detection coil method, excitation current method, virtual power method, shaft Voltage method, etc. These methods have their own advantages, some of which have mature application experience in power systems, and there is still room for development in various methods in terms of anti-interference and improving diagnostic sensitivity. There are many offline diagnosis methods for rotor windings, including: no-load test method, short-circuit test method, open transformer method, DC resistance method, AC impedance method, distributed voltage method, bipolar voltage balance test method, and RSO method. The off-line detection method cannot detect the short-circuit fault of the rotor winding of the synchronous motor in time, but it has been widely used by operation and maintenance personnel for many years. This is because: (1) The short-circuit fault of the rotor winding is not fatal to the synchronous motor. After a winding short-circuit fault, it is usually not an option to shut down the generator for maintenance immediately if the vibration of the generator is not serious. (2) The off-line detection method is completed in a shutdown state, which can effectively eliminate various interferences, and its detection reliability is high. Therefore, almost all large-scale synchronous motors have to carry out relevant off-line tests after the rotor winding short-circuit fault characteristics appear, among which, the open transformer method, distributed voltage method, and two-pole voltage balance test method need to extract the rotor. As we all know, taking out the rotor to check the fault requires longer downtime, high economic cost, and the vibration of the unit may become worse after the rotor is reinstalled. Therefore, the offline detection should try to avoid pulling out the generator rotor. No-load short-circuit test method, RSO method, DC resistance method and AC impedance method belong to the off-line detection methods that do not need to extract the generator rotor. The no-load short-circuit test method is to judge the short-circuit fault of the rotor winding by comparing the deviation between the no-load short-circuit curve of the generator and the normal state. The RSO method injects step signals at both ends of the rotor winding according to the principle of traveling waves, and judges the short-circuit fault of the rotor winding by comparing the difference of the reflected wave signals. The DC resistance method and the AC impedance method judge whether there is a short circuit fault of the rotor winding by measuring the direct and AC impedance of the rotor.

发明内容Contents of the invention

本发明要解决的技术问题是提供一种基于定子电流注入的同步电机转子绕组短路故障诊断方法。The technical problem to be solved by the present invention is to provide a method for diagnosing short-circuit faults of rotor windings of synchronous motors based on stator current injection.

本发明采用下述技术方案：The present invention adopts following technical scheme:

一种基于定子电流注入的同步电机转子绕组短路故障诊断方法，包括以下步骤：A method for diagnosing short-circuit faults in rotor windings of synchronous motors based on stator current injection, comprising the following steps:

步骤A.任一选择所述同步电机的定子的一相绕组作为交流电压输入绕组，连接交流电压源，所述交流电压输入绕组，在交流电压源激励下产生交流电流，在所述发电机内部形成脉振磁场；Step A. Select any one-phase winding of the stator of the synchronous motor as the AC voltage input winding, connect the AC voltage source, and the AC voltage input winding generates an AC current under the excitation of the AC voltage source, inside the generator Form a pulsating magnetic field;

步骤B.旋转所述同步电机的转子使转子绕组轴线与所述交流电压输入绕组轴线相重合，所述脉振磁场垂直穿过所述同步电机的转子绕组；Step B. Rotate the rotor of the synchronous motor so that the axis of the rotor winding coincides with the axis of the AC voltage input winding, and the pulse vibration magnetic field passes through the rotor winding of the synchronous motor vertically;

步骤C.测量所述交流电压输入绕组的电压和电流，计算测量交流阻抗Z'；Step C. Measure the voltage and current of the AC voltage input winding, and calculate and measure the AC impedance Z';

步骤D.计算故障判据值a％：Step D. Calculate the failure criterion value a%:

$a a % % = = | | \frac{{Z Z}^{' '} - - Z Z}{Z Z} | | \times \times 100100 % % - - - - - - ((11))$

其中Z为所述流电压输入绕组等电压条件下测量的正常交流阻抗；Wherein Z is the normal AC impedance measured under the voltage condition of the said flow voltage input winding;

步骤E.判断所述故障判据值a％是否大于预设阈值，如果是，则判定所述同步电机存在转子绕组短路故障；如果否，则判定所述同步电机转子绕组没有出现短路故障。Step E. Judging whether the fault criterion value a% is greater than a preset threshold value, if yes, it is determined that the synchronous motor has a rotor winding short circuit fault; if not, it is determined that the synchronous motor rotor winding does not have a short circuit fault.

作为优选，所述故障判据a％的阈值设定为0.2％。Preferably, the threshold of the failure criterion a% is set to 0.2%.

所述计算测量交流阻抗Z'的方法为：The method for calculating and measuring the AC impedance Z' is:

${Z Z}^{' '} = = \frac{{U u}^{' '}}{{I I}^{' '}} - - - - - - ((22))$

其中，U'表示计算测量交流阻抗Z'时，施加在所述交流电压输入绕组的交流电压值，I'表示所述交流电压输入绕组流过的交流电流值；Wherein, U' represents the AC voltage value applied to the AC voltage input winding when calculating and measuring the AC impedance Z', and I' represents the AC current value flowing through the AC voltage input winding;

所述交流电压输入绕组等电压条件下测量的正常交流阻抗Z的计算方法为：The calculation method of the normal AC impedance Z measured under the condition of the AC voltage input winding equal voltage is:

$Z Z = = \frac{U u}{I I} - - - - - - ((33))$

其中，U表示等电压条件下测量的正常交流阻抗Z时施加在所述交流电压输入绕组的交流电压值，I表示所述交流电压输入绕组流过的交流电流值。Wherein, U represents the AC voltage value applied to the AC voltage input winding when the normal AC impedance Z is measured under equal voltage conditions, and I represents the AC current value flowing through the AC voltage input winding.

采用上述技术方案所带来的有益效果在于：The beneficial effect brought by adopting the above-mentioned technical scheme is:

本发明的诊断方法不需要抽出转子，避免了转子回装后可能出现的振动状态变差情况。本方法的检测成本低且速度快，达到了较高的诊断精度，可广泛应用于同步电机转子绕组短路故障的离线检测。The diagnostic method of the present invention does not need to extract the rotor, which avoids possible deterioration of the vibration state after the rotor is reassembled. The detection cost of the method is low and the speed is fast, and high diagnostic accuracy is achieved, and it can be widely used in off-line detection of short-circuit faults of rotor windings of synchronous motors.

附图说明Description of drawings

图1是转子绕组等效电路。Figure 1 is the equivalent circuit of the rotor winding.

图2是转子q轴与A相轴线重合情况的示意图。Fig. 2 is a schematic diagram of the coincidence of the q-axis of the rotor and the axis of the A-phase.

图3是转子q轴与A相轴线重合情况的等效电路。Figure 3 is the equivalent circuit of the case where the rotor q-axis coincides with the A-phase axis.

图4是转子d轴与A相轴线重合情况的示意图。Fig. 4 is a schematic diagram of the coincidence of the d-axis of the rotor and the A-phase axis.

图5是转子d轴与A相轴线重合情况的等效电路。Figure 5 is the equivalent circuit of the case where the d-axis of the rotor coincides with the A-phase axis.

图6是转子绕组开路实验接线图。Figure 6 is the wiring diagram of the rotor winding open circuit experiment.

图7是转子绕组开路电压。Figure 7 is the rotor winding open circuit voltage.

图8是定转子绕组电压。Figure 8 is the stator and rotor winding voltage.

图9是定转子绕组电流。Figure 9 is the stator and rotor winding current.

图10是定子绕组电流。Figure 10 is the stator winding current.

图11是转子被短路绕组电流。Figure 11 is the winding current of the rotor being short-circuited.

图12是转子绕组通过二极管短路实验接线图。Figure 12 is a wiring diagram of the rotor winding through a diode short circuit experiment.

图13是定转子绕组电压。Figure 13 is the stator and rotor winding voltage.

图14是定转子绕组电流。Figure 14 is the stator and rotor winding current.

图15是转子绕组电流。Figure 15 is the rotor winding current.

图16是被短路绕组电流。Figure 16 is the short circuit winding current.

图17是定子绕组电流。Figure 17 is the stator winding current.

图中，1表示发电机转子绕组，2表示被短路的转子绕组，3表示q轴阻尼等效绕组，4表示d轴阻尼等效绕组，I_f表示励磁电流，表示施加在定子A相绕组上的交流电压，表示定子A相绕组流过的交流电流，表示发电机内部的主磁通，Z₁表示定子A相绕组的漏阻抗，Z_m定子A相绕组的激磁阻抗，Z_q表示q轴阻尼绕组漏阻抗归算值，K表示转子绕组断开或闭合的等效开关，Z_d表示d轴阻尼绕组漏阻抗归算值，Z_Short表示被短路的转子绕组漏阻抗归算值，C₁表示转子绕组N极0％位置的抽头，C₂表示转子绕组N极5％位置的抽头，C₃表示转子绕组N极15％位置的抽头，C₄表示转子绕组S极7.5％位置的抽头，C₅表示转子绕组S极0％位置的抽头。In the figure, 1 represents the generator rotor winding, 2 represents the short-circuited rotor winding, 3 represents the q-axis damping equivalent winding, 4 represents the d-axis damping equivalent winding, I _f represents the excitation current, Indicates the AC voltage applied to the A-phase winding of the stator, Indicates the AC current flowing through the stator A-phase winding, Indicates the main magnetic flux inside the generator, Z ₁ indicates the leakage impedance of the stator A-phase winding, Z _m the excitation impedance of the stator A-phase winding, Z _q indicates the calculated value of the leakage impedance of the q-axis damping winding, K indicates that the rotor winding is disconnected or Closed equivalent switch, Z _d represents the reduced value of the leakage impedance of the d-axis damping winding, Z _Short represents the reduced value of the leakage impedance of the short-circuited rotor winding, C ₁ represents the tap at the 0% position of the N pole of the rotor winding, and C ₂ represents the rotor The tap of the 5% position of the N pole of the winding, C3 represents the tap of the ₁₅ % position of the N pole of the rotor winding, _C4 represents the tap of the 7.5% position of the S pole of the rotor winding, and _C5 represents the tap of the 0% position of the S pole of the rotor winding.

具体实施方式Detailed ways

下面结合附图和具体实施方式对本发明作进一步详细的说明。The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

步骤A.任一选择所述同步电机的定子的一相绕组作为交流电压输入绕组，连接交流电压源，所述交流电压输入绕组，在交流电压源激励下产生交流电流，在所述发电机内部形成脉振磁场；Step A. Any one-phase winding of the stator of the synchronous motor is selected as an AC voltage input winding, connected to an AC voltage source, and the AC voltage input winding generates an AC current under the excitation of the AC voltage source, inside the generator Form a pulsating magnetic field;

${Z Z}^{' '} = = \frac{{U u}^{' '}}{{I I}^{' '}} - - - - - - ((22))$

$Z Z = = \frac{U u}{I I} - - - - - - ((33))$

同步电机的转子绕组发生短路故障后，其等效电路见图1，图中方框内部是整流部分，对于静止励磁和旋转励磁发电机，整流部分略有区别。图1中被短路绕组随发电机磁场同步旋转，短路绕组内部电流为零，失去励磁作用。After a short-circuit fault occurs in the rotor winding of a synchronous motor, its equivalent circuit is shown in Figure 1. The inside of the box in the figure is the rectification part. For static excitation and rotating excitation generators, the rectification part is slightly different. In Figure 1, the short-circuited winding rotates synchronously with the generator magnetic field, the internal current of the short-circuited winding is zero, and the excitation effect is lost.

将发电机转子旋转到某一位置保持不变，在定子A相绕组上施加交流电压，增大交流电压同时观察A相交流电流，确保其不超过额定值。Rotate the rotor of the generator to a certain position and keep it unchanged, apply AC voltage to the A-phase winding of the stator, increase the AC voltage and observe the A-phase AC current to ensure that it does not exceed the rated value.

1)转子q轴与A相轴线重合情况。此时转子绕组平行于A相绕组轴线，无交变磁通穿过转子绕组，被短路绕组内部无电流，仅q轴阻尼绕组有电流流过。定子A相绕组相当于变压器的原边绕组，q轴阻尼绕组相当于变压器副边的短路绕组，如图2和图3所示。1) The coincidence of the rotor q-axis and the A-phase axis. At this time, the rotor winding is parallel to the axis of the A-phase winding, no alternating magnetic flux passes through the rotor winding, and there is no current inside the short-circuited winding, and only the q-axis damping winding has current flowing through it. The A-phase winding of the stator is equivalent to the primary winding of the transformer, and the q-axis damping winding is equivalent to the short-circuit winding of the secondary side of the transformer, as shown in Figure 2 and Figure 3.

与之对应的，A相绕组的交流阻抗为：Correspondingly, the AC impedance of the A-phase winding is:

$Z Z = = {Z Z}_{11} + + \frac{11}{\frac{11}{{Z Z}_{m m}} + + \frac{11}{{Z Z}_{q q}}} - - - - - - ((44))$

其中，Z₁为定子A相绕组的漏阻抗，Z_m为激磁阻抗，Z_q为q轴阻尼绕组漏阻抗归算值。Among them, Z ₁ is the leakage impedance of the stator A-phase winding, Z _m is the excitation impedance, and Z _q is the reduced value of the leakage impedance of the q-axis damping winding.

2)转子d轴与A相绕组轴线重合情况。A相绕组产生的交变磁通垂直穿过转子绕组，当转子绕组存在匝间短路时，转子绕组感应交流电势，被短路绕组存在交流电流，d轴阻尼绕组中也有电流流过。A相绕组相当于变压器的原边绕组，d轴阻尼绕组、转子绕组以及被短路绕组相当于变压器副边绕组，类似于四绕组变压器，如图4和图5所示。2) The coincidence of the d-axis of the rotor with the axis of the A-phase winding. The alternating magnetic flux generated by the A-phase winding passes through the rotor winding vertically. When there is an inter-turn short circuit in the rotor winding, the rotor winding induces an AC potential, and there is an alternating current in the short-circuited winding, and current flows in the d-axis damping winding. The A-phase winding is equivalent to the primary winding of the transformer, and the d-axis damping winding, rotor winding and short-circuited winding are equivalent to the secondary winding of the transformer, similar to the four-winding transformer, as shown in Figure 4 and Figure 5.

对于静止励磁同步电机，可以将碳刷与滑环分离使得转子绕组开路，即图4、图5开关K保持常开状态，则对应的A相绕组交流阻抗为：For static excitation synchronous motors, the carbon brushes and slip rings can be separated to open the rotor winding, that is, the switch K in Figure 4 and Figure 5 remains normally open, and the corresponding AC impedance of the A-phase winding is:

$Z Z = = {Z Z}_{11} + + \frac{11}{\frac{11}{{Z Z}_{m m}} + + \frac{11}{{Z Z}_{d d}} + + \frac{11}{{Z Z}_{S S h h o o r r t t}}} - - - - - - ((55))$

其中，Z_d为d轴阻尼绕组漏阻抗归算值，Z_Short为被短路转子绕组漏阻抗归算值。Among them, Z _d is the reduced value of the leakage impedance of the d-axis damping winding, and Z _Short is the reduced value of the leakage impedance of the short-circuited rotor winding.

无刷励磁发电机采用二极管不控整流，转子绕组通过整流二极管短接。当转子绕组中感应正向交流电压且二极管导通时，即图4、图5中开关K闭合，此时的A相绕组交流阻抗为：The brushless excitation generator adopts diode uncontrolled rectification, and the rotor winding is short-circuited through the rectifier diode. When the forward AC voltage is induced in the rotor winding and the diode is turned on, that is, the switch K in Figure 4 and Figure 5 is closed, and the AC impedance of the A-phase winding at this time is:

$Z Z = = {Z Z}_{11} + + \frac{11}{\frac{11}{{Z Z}_{m m}} + + \frac{11}{{Z Z}_{d d}} + + \frac{11}{{Z Z}_{S S h h o o r r t t}} + + \frac{11}{{Z Z}_{f f}}} - - - - - - ((66))$

其中，Z_f为转子绕组漏阻抗归算值。Among them, Z _f is the reduced value of the leakage impedance of the rotor winding.

在交流电压的负半周二极管自然关断，开关K断开，则A相绕组交流阻抗按照式(5)计算。In the negative half cycle of the AC voltage, the diode is naturally turned off, and the switch K is turned off, then the AC impedance of the A-phase winding is calculated according to formula (5).

当转子绕组不存在匝间短路时，表达式(5)、(6)中包含Z_Short项均为零，A相绕组的交流阻抗为：When there is no inter-turn short circuit in the rotor winding, the Z _Short items contained in the expressions (5) and (6) are all zero, and the AC impedance of the A-phase winding is:

$Z Z = = {Z Z}_{11} + + \frac{11}{\frac{11}{{Z Z}_{m m}} + + \frac{11}{{Z Z}_{d d}}} - - - - - - ((77))$

$Z Z = = {Z Z}_{11} + + \frac{11}{\frac{11}{{Z Z}_{m m}} + + \frac{11}{{Z Z}_{d d}} + + \frac{11}{{Z Z}_{f f}}} - - - - - - ((88))$

可见，转子绕组短路后A相绕组的交流阻抗比转子绕组正常时小，该特征可用以判断发电机是否存在转子绕组短路故障。It can be seen that the AC impedance of the A-phase winding after the rotor winding is short-circuited is smaller than that when the rotor winding is normal, and this feature can be used to judge whether there is a rotor winding short-circuit fault in the generator.

为了验证本方法，在实验室一台7.5kVA故障模拟发电机组上进行了转子绕组短路故障模拟实验，实测了定子一相绕组的交流阻抗。该机组的参数见表1。In order to verify this method, a 7.5kVA fault simulation generator set in the laboratory carried out a simulation experiment of the rotor winding short-circuit fault, and measured the AC impedance of the stator one-phase winding. The parameters of the unit are shown in Table 1.

该发电机N极转子绕组的5％、15％引出两个抽头C₂、C₃，在S极的7.5％引出一个抽头C₄，加上转子绕组两端C₁、C₅，共5个抽头，通过碳刷引出，将相应接头短路可以模拟一定程度的转子绕组短路故障。5% and 15% of the N-pole rotor winding of the generator leads to two taps C ₂ and C ₃ , and 7.5% of the S-pole leads to a tap C ₄ , plus C ₁ and C ₅ at both ends of the rotor winding, a total of 5 The taps are drawn out through the carbon brushes, and short-circuiting the corresponding joints can simulate a certain degree of short-circuit fault of the rotor winding.

将定子A相绕组接在一台单相自耦调压器上，转子绕组保持开路，实验电路见图6，记录的数据包括定子A相绕组的交流电压、交流电流，转子绕组的开路电压和被短路绕组的短路电流。实验采样频率为10kHz，采样时间5秒。Connect the stator A-phase winding to a single-phase autovoltage regulator, and keep the rotor winding open. The experimental circuit is shown in Figure 6. The recorded data include the AC voltage and AC current of the stator A-phase winding, the open-circuit voltage of the rotor winding and The short-circuit current of the short-circuited winding. The experimental sampling frequency is 10kHz, and the sampling time is 5 seconds.

实验过程如下：The experimental process is as follows:

设置转子绕组为正常状态，升高单相自耦调压器输出电压至15.3V保持不变，保证A相电流和转子被短路绕组电流不超标，分别在转子绕组上设置不同的短路程度。对发电机一侧的动平衡盘进行标记，将平衡盘圆周等分为16份，分别标号1-16。保持标号1在转子正上方，记录数据，然后将转子沿顺时针每旋转22.5°记录一次数据，共记录17组数据，转子回到初始位置。Set the rotor winding to the normal state, increase the output voltage of the single-phase autovoltage regulator to 15.3V and keep it unchanged, ensure that the A-phase current and the short-circuited winding current of the rotor do not exceed the standard, and set different short-circuit degrees on the rotor windings. Mark the dynamic balance disc on one side of the generator, divide the circumference of the balance disc into 16 equal parts, and mark them as 1-16 respectively. Keep label 1 directly above the rotor, record data, then rotate the rotor clockwise every 22.5° to record data, a total of 17 sets of data are recorded, and the rotor returns to the initial position.

图7为不同短路程度、转子旋转不同角度时的转子绕组开路电压，可以看到：转子绕组感应的交流电压受转子位置影响明显，在转子转至30°和210°附近时绕组的感应电压最大，在120°和300度附近数值较小，这说明在30°和210°方向转子绕组轴线刚好与A相绕组轴线重合，A相绕组产生的脉振磁通垂直穿过转子绕组，磁通量最大，故感应出较大的电压；而在30°和210°方向时，磁通与转子绕组平行，穿过转子绕组的磁通量极小。当转子绕组出现匝间短路后，由于有效匝数减少，转子绕组开路电压明显下降，短路程度越严重开路电压下降越明显。Figure 7 shows the open-circuit voltage of the rotor winding at different short-circuit degrees and different angles of rotor rotation. It can be seen that the AC voltage induced by the rotor winding is significantly affected by the rotor position, and the induced voltage of the winding is the largest when the rotor rotates to around 30° and 210° , the values around 120° and 300° are small, which means that the axis of the rotor winding coincides with the axis of the A-phase winding in the direction of 30° and 210°, and the pulsating magnetic flux generated by the A-phase winding passes through the rotor winding vertically, and the magnetic flux is the largest. Therefore, a large voltage is induced; while in the directions of 30° and 210°, the magnetic flux is parallel to the rotor winding, and the magnetic flux passing through the rotor winding is extremely small. When the inter-turn short circuit occurs in the rotor winding, the open circuit voltage of the rotor winding decreases obviously due to the reduction of the effective number of turns. The more serious the short circuit is, the more obvious the open circuit voltage drops.

图8、图9分别为转子绕组短路5％、转子旋转22.5°时的定、转子绕组电压、电流波形，此时定转子轴线几乎重合。可以看到：由于转子绕组匝数较多，转子绕组感应电压较大，最大值接近100V。Figure 8 and Figure 9 are the voltage and current waveforms of the stator and rotor windings when the rotor winding is short-circuited by 5% and the rotor rotates 22.5°, respectively. At this time, the axes of the stator and rotor are almost coincident. It can be seen that due to the large number of turns of the rotor winding, the induced voltage of the rotor winding is relatively large, and the maximum value is close to 100V.

图10为不同短路程度、转子旋转不同角度时的A相绕组电流值。Figure 10 shows the A-phase winding current values at different short-circuit degrees and different angles of rotor rotation.

可以看到：当转子绕组正常时，A相电流在转子旋转至120°和300°方向附近的数值较大，此时A相绕组轴线与转子q轴重合，q轴方向为小齿区，开槽较多，磁阻较大，导致激磁阻抗Z_m较小，故A相电流较大；与之对应，在30°和210°方向时A相绕组轴线与转子d轴重合，A相电流较小。转子绕组出现匝间短路故障后，从图10可以看到：当转子d轴与A相绕组轴线重合时，A相电流呈现出明显的增大趋势，且短路程度越重A相电流增大越明显。此时A相绕组产生的交变磁场垂直穿过短路的转子绕组，在被短路绕组内部产生了环流，该环流对激磁磁场起去磁作用，减小了发电机内部的主磁通，与之对应，A相绕组交流阻抗下降，电流上升。It can be seen that when the rotor winding is normal, the value of phase A current is relatively large when the rotor rotates to 120° and 300°. There are more slots and larger reluctance, resulting in smaller excitation impedance Z _m , so the A-phase current is larger; correspondingly, in the 30° and 210° directions, the axis of the A-phase winding coincides with the d-axis of the rotor, and the A-phase current is relatively large. Small. After the turn-to-turn short-circuit fault occurs in the rotor winding, it can be seen from Figure 10 that when the d-axis of the rotor coincides with the axis of the A-phase winding, the A-phase current presents an obvious increasing trend, and the heavier the short-circuit degree, the more obvious the A-phase current increases . At this time, the alternating magnetic field generated by the A-phase winding passes through the short-circuited rotor winding vertically, and a circulating current is generated inside the short-circuited winding, which demagnetizes the exciting magnetic field and reduces the main magnetic flux inside the generator. Correspondingly, the AC impedance of the A-phase winding decreases and the current increases.

图11为被短路转子绕组内部的短路电流，可以看到，短路电流变化规律与图7的转子绕组开路电压变化规律基本相同。Figure 11 shows the short-circuit current inside the short-circuited rotor winding. It can be seen that the variation law of the short-circuit current is basically the same as the variation law of the open-circuit voltage of the rotor winding in Figure 7.

随着短路程度增加，短路电流呈现出减小趋势。这是因为：被短路绕组内部的感应电动势与短路绕组匝数成正比，短路绕组的漏抗与短路绕组匝数的平方成正比，短路程度增加时漏抗增大更快，故短路电流呈现减小趋势。As the short-circuit degree increases, the short-circuit current shows a decreasing trend. This is because: the induced electromotive force inside the short-circuited winding is proportional to the number of turns of the short-circuited winding, and the leakage reactance of the short-circuited winding is proportional to the square of the number of turns of the short-circuited winding. When the degree of short-circuit increases, the leakage reactance increases faster, so the short-circuit current decreases. small trend.

通过上述分析可知，转子绕组轴线与定子绕组轴线重合时，短路绕组的去磁作用以及改变定子绕组交流阻抗的效果得到充分体现，下面以转子转过22.5°的第二组数据为例，计算不同短路程度下的定子绕组交流阻抗，见表2。可以看到：A相绕组的交流阻抗值在转子绕组短路故障发生后明显减小，但并非与短路程度成正相关关系。Through the above analysis, it can be seen that when the axis of the rotor winding coincides with the axis of the stator winding, the demagnetization effect of the short-circuit winding and the effect of changing the AC impedance of the stator winding are fully reflected. The following takes the second set of data when the rotor rotates 22.5° as an example, and the calculation is different See Table 2 for the AC impedance of the stator winding under short-circuit conditions. It can be seen that the AC impedance value of phase A winding decreases significantly after the rotor winding short-circuit fault occurs, but it is not positively correlated with the degree of short-circuit.

对于旋转励磁发电机，转子绕组与多相旋转二极管构成闭合回路，可以将二极管组等效为单个二极管，见图12。当转子绕组中感应交流电动势时，励磁回路不断在导通和关断状态间切换，转子绕组对主磁场也起到一定的去磁作用。For rotating excitation generators, the rotor winding and multi-phase rotating diodes form a closed loop, and the diode group can be equivalent to a single diode, as shown in Figure 12. When the AC electromotive force is induced in the rotor winding, the excitation circuit is constantly switched between on and off states, and the rotor winding also has a certain demagnetization effect on the main magnetic field.

在实验电机的转子绕组两端接入一只二极管。该二极管的额定导通电流10A，反向耐受电压1000V。Connect a diode at both ends of the rotor winding of the experimental motor. The diode has a rated conduction current of 10A and a reverse withstand voltage of 1000V.

在A相绕组施加交流电压有效值为14.3V，图13为转子绕组短路5％、转子旋转22.5°时的定、转子绕组电压波形。可以看到：转子绕组感应电压的正半周期二极管导通，因此转子绕组两端电压接近于零，在转子绕组感应电压的负半周期，转子绕组的电感储能起到了续流作用，二极管延时关断，图13的负脉冲部分对应二极管反向关断。The effective value of the AC voltage applied to the A-phase winding is 14.3V. Figure 13 shows the voltage waveforms of the stator and rotor windings when the rotor winding is short-circuited by 5% and the rotor rotates 22.5°. It can be seen that in the positive half cycle of the induced voltage of the rotor winding, the diode conducts, so the voltage at both ends of the rotor winding is close to zero. When it is turned off, the negative pulse part in Figure 13 corresponds to the reverse turn-off of the diode.

图14为转子绕组短路5％、转子旋转22.5°时的定、转子绕组电流波形。与图9所示的转子绕组开路时的情况相比较，图14中转子绕组的短路电流大幅下降。Figure 14 shows the current waveforms of the stator and rotor windings when the rotor winding is short-circuited by 5% and the rotor rotates 22.5°. Compared with the situation when the rotor winding is open circuit shown in Fig. 9, the short-circuit current of the rotor winding in Fig. 14 is greatly reduced.

转子绕组通过二极管形成通路，对主磁场起去磁作用，使得主磁场显著减小。故被短路绕组内的感应电动势降低，短路电流下降。The rotor winding forms a path through the diode, which demagnetizes the main magnetic field, so that the main magnetic field is significantly reduced. Therefore, the induced electromotive force in the short-circuited winding decreases, and the short-circuit current decreases.

图15、图16分别为不同短路程度、转子旋转至不同方向时的转子绕组电流及被短路绕组电流值。Figure 15 and Figure 16 respectively show the rotor winding current and the short-circuited winding current value when the rotor rotates to different directions with different short-circuit degrees.

图17为不同短路程度下的定子绕组电流，可见，由于转子绕组被二极管短接，等效交流阻抗显著下降，故定子电流较转子绕组开路时显著上升。此外还可以看到：在30°和210°方向附近，定子电流并非随短路程度增大而一直增加，而是呈现先增大后减小的趋势，但始终大于绕组正常时的数值。Figure 17 shows the stator winding currents under different short-circuit conditions. It can be seen that since the rotor winding is short-circuited by diodes, the equivalent AC impedance decreases significantly, so the stator current increases significantly compared with the rotor winding open circuit. In addition, it can be seen that near the directions of 30° and 210°, the stator current does not always increase with the increase of the short circuit degree, but presents a trend of first increasing and then decreasing, but it is always greater than the value when the winding is normal.

表3为转子转过22.5°时定子绕组交流阻抗随短路程度的变化规律。可以看到：旋转励磁发电机发生转子绕组匝间短路后，由于转子绕组通过旋转二极管短接，故被短路绕组对定子一相绕组交流阻抗的影响不如转子绕组开路时明显，但仍可识别转子绕组匝间短路故障。Table 3 shows the change law of the AC impedance of the stator winding with the degree of short circuit when the rotor rotates through 22.5°. It can be seen that after the inter-turn short circuit of the rotor winding in the rotating excitation generator, because the rotor winding is short-circuited through the rotating diode, the impact of the short-circuited winding on the AC impedance of the stator one-phase winding is not as obvious as when the rotor winding is open, but the rotor can still be identified Turn-to-turn short circuit fault.

以上显示和描述了本发明的基本原理和主要特征和本发明的优点。本行业的技术人员应该了解，本发明不受上述实施例的限制，上述实施例和说明书中描述的只是说明本发明的原理，在不脱离本发明精神和范围的前提下，本发明还会有各种变化和改进，这些变化和改进都落入要求保护的本发明范围内。本发明要求保护范围由所附的权利要求书及其等效物界定。The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments, and what described in the above-mentioned embodiments and the description only illustrates the principles of the present invention, and the present invention will also have other functions without departing from the spirit and scope of the present invention. Variations and improvements are possible, which fall within the scope of the claimed invention. The protection scope of the present invention is defined by the appended claims and their equivalents.

表1Table 1

表2Table 2

表3table 3

Claims

1. a synchronous motor rotor winding short-circuit fault diagnosis method based on stator current injection, is characterized in that: comprise the following steps:

Step A. Select any one-phase winding of the stator of the synchronous motor as the AC voltage input winding, connect the AC voltage source, and the AC voltage input winding generates an AC current under the excitation of the AC voltage source, inside the generator Form a pulsating magnetic field;

Step B. Rotate the rotor of the synchronous motor so that the axis of the rotor winding coincides with the axis of the AC voltage input winding, and the pulse vibration magnetic field passes through the rotor winding of the synchronous motor vertically;

Step C. Measure the voltage and current of the AC voltage input winding, and calculate and measure the AC impedance Z';

Step D. Calculate the failure criterion value a%:

a a % % = = | | \frac{{Z Z}^{' '} - - Z Z}{Z Z} | | \times \times 100100 % % - - - - - - ((11))

Wherein Z is the normal AC impedance measured under the voltage condition of the said flow voltage input winding;

Step E. Judging whether the fault criterion value a% is greater than a preset threshold value, if yes, it is determined that the synchronous motor has a rotor winding short circuit fault; if not, it is determined that the synchronous motor rotor winding does not have a short circuit fault.

2. The method for diagnosing short-circuit faults of synchronous motor rotor windings based on stator current injection according to claim 1, characterized in that: the threshold value of the fault criterion a% is set to 0.2%.

3. The method for diagnosing short-circuit faults of synchronous motor rotor windings based on stator current injection according to claim 1, characterized in that: the method for calculating and measuring the AC impedance Z' is:

{Z Z}^{' '} = = \frac{{U u}^{' '}}{{I I}^{' '}} - - - - - - ((22))

Wherein, U' represents the AC voltage value applied to the AC voltage input winding when calculating and measuring the AC impedance Z', and I' represents the AC current value flowing through the AC voltage input winding;

The calculation method of the normal AC impedance Z measured under the condition of the AC voltage input winding equal voltage is:

Z Z = = \frac{U u}{I I} - - - - - - ((33))

Wherein, U represents the AC voltage value applied to the AC voltage input winding when the normal AC impedance Z is measured under equal voltage conditions, and I represents the AC current value flowing through the AC voltage input winding.