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

Abstract

The invention discloses a synchronous motor rotor winding short circuit fault diagnosis method based on stator current injection, and the method comprises the following steps: selecting a winding of any phase of a stator of a synchronous motor as an AC voltage input winding, generating alternating current under the excitation of an AC voltage source, and forming a pulse-shake magnetic field in a power generator; rotating the rotor of a synchronous motor and enabling the pulse-shake magnetic field to vertically pass through the rotor winding of the synchronous motor; measuring the voltage and current of the AC voltage input winding, and calculating and measuring AC impedance; calculating a fault judgment value (shown in the description); and judging that there is a rotor winding short circuit fault happening to the synchronous motor if the fault judgment value is greater than a preset threshold value. The method provided by the invention does not need to take out the rotor, and avoids a condition that a possible vibrating state of the rotor becomes poor after being reassembled The method is low in detection cost, is high in speed, achieves a higher diagnosis precision, and can be widely used for the off-line detection of the synchronous motor rotor winding short circuit fault.

Description

Based on the synchronous electric motor rotor Winding Short Fault Diagnosis method that stator current injects

Technical field

The present invention relates to a kind of synchronous electric motor rotor Winding Short Fault Diagnosis method, especially a kind of synchronous electric motor rotor Winding Short Fault Diagnosis method injected based on stator current, belongs to technical field of generators.

Background technology

The rotor windings short-circuit fault of synchronous motor is a puzzlement engineering technical personnel's difficult problem always, achieved about the rotor windings short-circuit fault diagnosis of synchronous motor in recent years and be in progress fast, some detection methods constantly improve in actual applications and develop, help operations staff to shorten fault handling time, reduce the unit outage time.

At present off-line and online two kinds of modes are mainly comprised to the diagnosis of rotor windings short-circuit, wherein inline diagnosis mode is due to can Timeliness coverage fault and being praised highly by people, current on-line monitoring method mainly comprises: detecting coil method, exciting current method, fictitious power method, shaft voltage method etc., these methods respectively have superiority, some of them method has had ripe application experience in electric system, and in sensitivity is diagnosed in anti-interference and raising, various method all also has certain development space.The off-line diagnostic method of rotor windings is more, specifically comprises: no-load test method, short-circuit test method, opening transformer method, DC resistance method, AC impedence method, spread voltage method, the two poles of the earth balance of voltage test method(s), RSO method.Off-line checking method can not the rotor windings short-circuit fault of Timeliness coverage synchronous motor; but be run for many years always, maintainer widely uses; this is because: (1) rotor windings short-circuit fault is for synchronous motor non-lethal fault; after rotor windings short-circuit fault appears in generator, hard stop usually can not be selected to overhaul when Generator Vibration is not serious.(2) off-line checking method completes under stopped status, and can effectively get rid of all kinds of interference, its detecting reliability is higher.Therefore, nearly all Large Synchronous Machine, after there is rotor windings short-circuit fault signature, all will carry out the off-line test test of being correlated with, and wherein, opening transformer method, spread voltage method, the two poles of the earth balance of voltage test method(s) etc. need to extract rotor out.As everyone knows, extract rotor out and check that fault needs the idle time more grown, financial cost is high, and may occur that rotor returns the rear unit vibration variation phenomenon of dress, and therefore, offline inspection should be avoided extracting generator amature out as far as possible.Unloaded short-circuit test method, RSO method, DC resistance method and AC impedence method just belong to the off-line checking method not needing to extract generator amature out.Unloaded short-circuit test method be by the unloaded short-circuit curve of contrast generator and normal time deviation judge rotor windings short-circuit fault.RSO method injects step signal according to row ripple principle respectively at the two ends of rotor windings, by comparing reflection wave signal diversity judgement rotor windings short-circuit fault.DC resistance method and AC impedence method are that straight, the AC impedance by measuring rotor judges whether rotor windings short-circuit fault occurs.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of synchronous electric motor rotor Winding Short Fault Diagnosis method injected based on stator current.

The present invention adopts following technical proposals:

Based on the synchronous electric motor rotor Winding Short Fault Diagnosis method that stator current injects, comprise the following steps:

Steps A. a phase winding of the stator of the described synchronous motor of arbitrary selection inputs winding as alternating voltage, connect alternating-current voltage source, described alternating voltage input winding, produces alternating current, forms impulsive magnetic field at described generator under alternating voltage source forcing;

The rotor that step B. rotates described synchronous motor makes rotor windings axis and described alternating voltage input winding axis to coincide, and described impulsive magnetic field passes perpendicularly through the rotor windings of described synchronous motor;

Step C. measures the voltage and current of described alternating voltage input winding, computation and measurement AC impedance Z';

Step D. calculates failure criterion value a%:

$a\%=\left|\frac{Z^{\′}-Z}{Z}\right|\×100\%---\left(1\right)$

Wherein Z is the normal communication impedance of measuring under the voltage conditions such as described stream voltage input winding;

Step e. judge whether described failure criterion value a% is greater than predetermined threshold value, if so, then judge that described synchronous motor exists rotor windings short-circuit fault; If not, then judge that described synchronous electric motor rotor winding does not occur short trouble.

As preferably, the threshold value of described failure criterion a% is set as 0.2%.

The method of described computation and measurement AC impedance Z' is:

$Z^{\′}=\frac{U^{\′}}{I^{\′}}---\left(2\right)$

Wherein, when U' represents computation and measurement AC impedance Z', be applied to the ac voltage of described alternating voltage input winding, I' represents the AC current values that described alternating voltage input winding flows through;

The computing method of the normal communication impedance Z measured under the voltage conditions such as described alternating voltage input winding are:

$Z=\frac{U}{I}---\left(3\right)$

Wherein, be applied to the ac voltage of described alternating voltage input winding during the normal communication impedance Z that U measures under the voltage conditions such as representing, I represents the AC current values that described alternating voltage input winding flows through.

The beneficial effect adopting technique scheme to bring is:

Diagnostic method of the present invention does not need to extract rotor out, avoids the vibrational state variation situation that may occur after rotor returns dress.The testing cost of this method is low and speed fast, reaches higher diagnostic accuracy, can be widely used in the offline inspection of synchronous electric motor rotor short circuit in winding fault.

Accompanying drawing explanation

Fig. 1 is rotor windings equivalent electrical circuit.

Fig. 2 is that rotor q axle overlaps with A phase axis the schematic diagram of situation.

Fig. 3 is that rotor q axle overlaps with A phase axis the equivalent electrical circuit of situation.

Fig. 4 is that rotor d axle overlaps with A phase axis the schematic diagram of situation.

Fig. 5 is that rotor d axle overlaps with A phase axis the equivalent electrical circuit of situation.

Fig. 6 is rotor windings open circuit experimental wiring figure.

Fig. 7 is rotor windings open-circuit voltage.

Fig. 8 is Stator and Rotor Windings voltage.

Fig. 9 is Stator and Rotor Windings electric current.

Figure 10 is stator winding current.

Figure 11 is that rotor is shorted winding current.

Figure 12 is that rotor windings is by shorted diode experimental wiring figure.

Figure 13 is Stator and Rotor Windings voltage.

Figure 14 is Stator and Rotor Windings electric current.

Figure 15 is rotor winding current.

Figure 16 is shorted winding current.

Figure 17 is stator winding current.

In figure, 1 represents generator amature winding, and 2 represent the rotor windings be shorted, and 3 represent q axle damping equivalent winding, and 4 represent d axle damping equivalent winding, I _frepresent exciting current, represent the alternating voltage be applied on stator A phase winding, represent the alternating current that stator A phase winding flows through, represent the main flux of generator, Z ₁represent the leakage impedance of stator A phase winding, Z _mthe exciting impedance of stator A phase winding, Z _qrepresent q axle damping winding leakage impedance reduction value, K represents that rotor windings disconnects or closed equivalent switch, Z _drepresent d axle damping winding leakage impedance reduction value, Z _shortrepresent the rotor windings leakage impedance reduction value be shorted, C ₁represent the tap of position, rotor windings N pole 0%, C ₂represent the tap of position, rotor windings N pole 5%, C ₃represent the tap of position, rotor windings N pole 15%, C ₄represent the tap of position, rotor windings S pole 7.5%, C ₅represent the tap of position, rotor windings S pole 0%.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is further detailed explanation.

Based on the synchronous electric motor rotor Winding Short Fault Diagnosis method that stator current injects, comprise the following steps:

Steps A. a phase winding of the stator of the described synchronous motor of arbitrary selection inputs winding as alternating voltage, connect alternating-current voltage source, described alternating voltage input winding, produces alternating current, forms impulsive magnetic field at described generator under alternating voltage source forcing;

The rotor that step B. rotates described synchronous motor makes rotor windings axis and described alternating voltage input winding axis to coincide, and described impulsive magnetic field passes perpendicularly through the rotor windings of described synchronous motor;

Step C. measures the voltage and current of described alternating voltage input winding, computation and measurement AC impedance Z';

Step D. calculates failure criterion value a%:

$a\%=\left|\frac{Z^{\′}-Z}{Z}\right|\×100\%---\left(1\right)$

Wherein Z is the normal communication impedance of measuring under the voltage conditions such as described stream voltage input winding;

Step e. judge whether described failure criterion value a% is greater than predetermined threshold value, if so, then judge that described synchronous motor exists rotor windings short-circuit fault; If not, then judge that described synchronous electric motor rotor winding does not occur short trouble.

As preferably, the threshold value of described failure criterion a% is set as 0.2%.

The method of described computation and measurement AC impedance Z' is:

$Z^{\′}=\frac{U^{\′}}{I^{\′}}---\left(2\right)$

Wherein, when U' represents computation and measurement AC impedance Z', be applied to the ac voltage of described alternating voltage input winding, I' represents the AC current values that described alternating voltage input winding flows through;

The computing method of the normal communication impedance Z measured under the voltage conditions such as described alternating voltage input winding are:

$Z=\frac{U}{I}---\left(3\right)$

Wherein, be applied to the ac voltage of described alternating voltage input winding during the normal communication impedance Z that U measures under the voltage conditions such as representing, I represents the AC current values that described alternating voltage input winding flows through.

The rotor windings of synchronous motor is short-circuited after fault, and in its equivalent circuit Fig. 1, figure, square frame inside is rectifying part, and for static excitation and rotating excitation generator, rectifying part is slightly distinguished.Be shorted winding in Fig. 1 with generator field synchronous rotary, short-circuited winding internal current is zero, loses excitation effect.

Generator amature is rotated to a certain position to remain unchanged, stator A phase winding applies alternating voltage, increase alternating voltage and observe A cross streams electric current simultaneously, guarantee that it is no more than ratings.

1) rotor q axle overlaps with A phase axis situation.Now rotor windings is parallel to A phase winding axis, and without alternating flux through rotor windings, be shorted the inner no current of winding, only q axle damping winding has electric current to flow through.Stator A phase winding is equivalent to the former limit winding of transformer, and q axle damping winding is equivalent to the short-circuited winding of transformer secondary, as shown in Figures 2 and 3.

Corresponding with it, the AC impedance of A phase winding is:

$Z=Z_1+\frac{1}{\frac{1}{Z_m}+\frac{1}{Z_q}}---\left(4\right)$

Wherein, Z ₁for the leakage impedance of stator A phase winding, Z _mfor exciting impedance, Z _qfor q axle damping winding leakage impedance reduction value.

2) rotor d axle and A phase winding dead in line situation.The alternating flux that A phase winding produces passes perpendicularly through rotor windings, and when rotor windings exists turn-to-turn short circuit, rotor windings induction exchanges electromotive force, is shorted winding and there is alternating current, also have electric current to flow through in d axle damping winding.A phase winding is equivalent to the former limit winding of transformer, d axle damping winding, rotor windings and be shorted winding and be equivalent to transformer secondary winding, is similar to four winding transformers, as shown in Figure 4 and Figure 5.

For static excitation synchronous motor, carbon brush can be separated with slip ring and rotor windings is opened a way, namely Fig. 4, Fig. 5 K switch keeps normally open, then corresponding A phase winding AC impedance is:

$Z=Z_1+\frac{1}{\frac{1}{Z_m}+\frac{1}{Z_d}+\frac{1}{Z_{Short}}}---\left(5\right)$

Wherein, Z _dfor d axle damping winding leakage impedance reduction value, Z _shortfor being shorted rotor windings leakage impedance reduction value.

Brushless excitation generator adopts diode uncontrollable rectifier, and rotor windings is by commutation diode short circuit.When respond to forward alternating voltage in rotor windings and diode current flow time, namely Fig. 4, Fig. 5 breaker in middle K closes, and A phase winding AC impedance is now:

$Z=Z_1+\frac{1}{\frac{1}{Z_m}+\frac{1}{Z_d}+\frac{1}{Z_{Short}}+\frac{1}{Z_f}}---\left(6\right)$

Wherein, Z _ffor rotor windings leakage impedance reduction value.

Naturally turn off at the negative half period diode of alternating voltage, K switch disconnects, then A phase winding AC impedance calculates according to formula (5).

When rotor windings does not exist turn-to-turn short circuit, in expression formula (5), (6), comprise Z _shortthe AC impedance that item is zero, A phase winding is:

$Z=Z_1+\frac{1}{\frac{1}{Z_m}+\frac{1}{Z_d}}---\left(7\right)$

$Z=Z_1+\frac{1}{\frac{1}{Z_m}+\frac{1}{Z_d}+\frac{1}{Z_f}}---\left(8\right)$

Visible, little when after rotor windings short-circuit, the AC impedance of A phase winding is more normal than rotor windings, this feature can in order to judge whether generator exists rotor windings short-circuit fault.

In order to verify this method, one, laboratory 7.5kVA fault simulation genset carrying out the experiment of rotor windings short-circuit fault simulation, has surveyed the AC impedance of stator one phase winding.The parameter of this unit is in table 1.

5%, 15% of this generator N pole rotor windings draws two tap C ₂, C ₃, draw a tap C in 7.5% of S pole ₄, add rotor windings two ends C ₁, C ₅, totally 5 taps, are drawn by carbon brush, corresponding joint short circuit can be simulated rotor windings short-circuit fault to a certain degree.

Be connected on by stator A phase winding on a single-phase self-coupling pressure regulator, rotor windings keeps open circuit, and experimental circuit is shown in Fig. 6, and the data of record comprise alternating voltage, the alternating current of stator A phase winding, open-circuit voltage and the short-circuit current being shorted winding of rotor windings.Experiment sample frequency is 10kHz, 5 seconds sampling times.

Experimentation is as follows:

Arranging rotor windings is normal condition, raises single-phase self-coupling pressure regulator output voltage and remains unchanged to 15.3V, ensures that A phase current and rotor are shorted winding current and do not exceed standard, arranges different degree of short circuit respectively on rotor windings.Marking the transient equilibrium dish of generator side, is 16 parts by balancing frame circumference equal dividing, respectively label 1-16.Keep label 1 directly over rotor, record data, then rotor is often rotated 22.5 ° of record one secondary data along clockwise, record 17 groups of data altogether, initial position got back to by rotor.

Rotor windings open-circuit voltage when Fig. 7 is different degree of short circuit, rotor different rotation angle, can see: the alternating voltage of rotor windings induction affects obviously by rotor-position, when rotor goes near 30 ° and 210 °, the induced voltage of winding is maximum, near 120 ° and 300 degree, numerical value is less, this illustrate 30 ° and 210 ° of direction rotor windings axis just with the dead in line of A phase winding, the pulsating magnetic flux that A phase winding produces passes perpendicularly through rotor windings, magnetic flux is maximum, therefore induces larger voltage; And when 30 ° and 210 ° of directions, magnetic flux is parallel with rotor windings, the magnetic flux through rotor windings is minimum.After turn-to-turn short circuit appears in rotor windings, because effective turn reduces, rotor windings open-circuit voltage obviously declines, and the more serious open-circuit voltage of degree of short circuit declines more obvious.

Stator and rotor winding voltage, current waveform when Fig. 8, Fig. 9 are respectively rotor windings short-circuit 5%, rotor rotates 22.5 °, now rotor axis almost overlaps.Can see: because the rotor windings number of turn is more, rotor windings induced voltage is comparatively large, and maximal value is close to 100V.

A phase winding current value when Figure 10 is different degree of short circuit, rotor different rotation angle.

Can see: when rotor windings is normal, the numerical value that A phase current rotates near 120 ° and 300 ° of directions at rotor is comparatively large, and now A phase winding axis overlaps with rotor q axle, and q direction of principal axis is little Chi district, slots more, and magnetic resistance is comparatively large, causes exciting impedance Z _mless, therefore A phase current is larger; Corresponding with it, when 30 ° and 210 ° of directions, A phase winding axis overlaps with rotor d axle, and A phase current is less.After shorted-turn fault appears in rotor windings, as seen from Figure 10: when rotor d axle and the dead in line of A phase winding, A phase current presents obvious increase tendency, and degree of short circuit heavier A phase current increase more obvious.The alternating magnetic field that now A phase winding produces passes perpendicularly through the rotor windings of short circuit, and create circulation being shorted winding inside, this circulation plays demagnetizing effect to excitatory magnetic field, reduce the main flux of generator, corresponding with it, A phase winding AC impedance declines, and electric current rises.

Figure 11 is the short-circuit current being shorted rotor windings inside, can see, short-circuit current Changing Pattern is substantially identical with the rotor windings open circuit voltage variations rule of Fig. 7.

Along with degree of short circuit increases, short-circuit current presents reduction trend.This is because: the induction electromotive force being shorted winding inside is directly proportional to the short-circuited winding number of turn, and square being directly proportional of the leakage reactance of short-circuited winding and the short-circuited winding number of turn, when degree of short circuit increases, leakage reactance increases faster, therefore short-circuit current presents reduction trend.

Known by above-mentioned analysis, when rotor windings axis and stator winding dead in line, the demagnetizing effect of short-circuited winding and the effect of change stator winding AC impedance find full expression, second group of data instance of 22.5 ° is turned over below with rotor, calculate the stator winding AC impedance under different degree of short circuit, in table 2.Can see: the AC impedance of A phase winding obviously reduces after rotor windings short-circuit fault occurs, but not becomes positive correlation with degree of short circuit.

For rotating excitation generator, rotor windings and heterogeneous rotating diode form closed-loop path, diode group can be equivalent to single diode, see Figure 12.When responding to AC electromotive force in rotor windings, energized circuit constantly switches between turn-on and turn-off state, and rotor windings also plays certain demagnetizing effect to main field.

A diode is accessed at the rotor windings two ends of experiment motor.The specified On current 10A of this diode, reverse withstand voltage 1000V.

Stator and rotor winding voltage waveform when to apply alternating voltage effective value be 14.3V, Figure 13 to A phase winding is rotor windings short-circuit 5%, rotor rotates 22.5 °.Can see: the positive half period diode current flow of rotor windings induced voltage, therefore rotor windings both end voltage is close to zero, at the negative half-cycle of rotor windings induced voltage, the inductive energy storage of rotor windings serves afterflow effect, diode time delayed turn-off, the corresponding diode reverse of negative pulse portions of Figure 13 turns off.

Stator and rotor winding current waveform when Figure 14 is rotor windings short-circuit 5%, rotor rotates 22.5 °.Compared with situation when opening a way with the rotor windings shown in Fig. 9, the short-circuit current of Figure 14 rotor winding declines to a great extent.

Rotor windings forms path by diode, plays demagnetizing effect to main field, and main field is significantly reduced.Therefore the induction electromotive force be shorted in winding reduces, short-circuit current declines.

Figure 15, Figure 16 are respectively different degree of short circuit, rotor rotates to rotor winding current during different directions and is shorted winding current values.

Figure 17 is the stator winding current under different degree of short circuit, visible, and because rotor windings is by diode short circuit, equivalent AC impedance significantly declines, therefore stator current significantly rises when comparatively rotor windings is opened a way.Can see in addition: near 30 ° and 210 ° of directions, stator current not increases with degree of short circuit and increases always, but presents the trend of first increases and then decreases, but be greater than all the time winding normal time numerical value.

Table 3 is for stator winding AC impedance when rotor turns over 22.5 ° is with the Changing Pattern of degree of short circuit.Can see: after rotating excitation generator generation rotor interturn short-circuit, because rotor windings is by rotating diode short circuit, therefore be shorted winding on the impact of stator one phase winding AC impedance not as obvious during rotor windings open circuit, but still identifiable design rotor interturn short-circuit fault.

More than show and describe ultimate principle of the present invention and principal character and advantage of the present invention.The technician of the industry should understand; the present invention is not restricted to the described embodiments; what describe in above-described embodiment and instructions just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.Application claims protection domain is defined by appending claims and equivalent thereof.

Table 1

Table 2

Table 3

Claims (3)

1., based on the synchronous electric motor rotor Winding Short Fault Diagnosis method that stator current injects, it is characterized in that: comprise the following steps:

Steps A. a phase winding of the stator of the described synchronous motor of arbitrary selection inputs winding as alternating voltage, connect alternating-current voltage source, described alternating voltage input winding, produces alternating current, forms impulsive magnetic field at described generator under alternating voltage source forcing;

The rotor that step B. rotates described synchronous motor makes rotor windings axis and described alternating voltage input winding axis to coincide, and described impulsive magnetic field passes perpendicularly through the rotor windings of described synchronous motor;

Step C. measures the voltage and current of described alternating voltage input winding, computation and measurement AC impedance Z';

Step D. calculates failure criterion value a%:

$a\%=\left|\frac{Z^{\′}-Z}{Z}\right|\×100\%---\left(1\right)$

Wherein Z is the normal communication impedance of measuring under the voltage conditions such as described stream voltage input winding;

Step e. judge whether described failure criterion value a% is greater than predetermined threshold value, if so, then judge that described synchronous motor exists rotor windings short-circuit fault; If not, then judge that described synchronous electric motor rotor winding does not occur short trouble.

2. the synchronous electric motor rotor Winding Short Fault Diagnosis method injected based on stator current according to claim 1, is characterized in that: the threshold value of described failure criterion a% is set as 0.2%.

3. the synchronous electric motor rotor Winding Short Fault Diagnosis method injected based on stator current according to claim 1, is characterized in that: the method for described computation and measurement AC impedance Z' is:

$Z^{\′}=\frac{U^{\′}}{I^{\′}}---\left(2\right)$

Wherein, when U' represents computation and measurement AC impedance Z', be applied to the ac voltage of described alternating voltage input winding, I' represents the AC current values that described alternating voltage input winding flows through;

The computing method of the normal communication impedance Z measured under the voltage conditions such as described alternating voltage input winding are:

$Z=\frac{U}{I}---\left(3\right)$

Wherein, be applied to the ac voltage of described alternating voltage input winding during the normal communication impedance Z that U measures under the voltage conditions such as representing, I represents the AC current values that described alternating voltage input winding flows through.