CN104764974A - Turn-to-turn short circuit fault diagnosis method for rotor winding of brushless excitation generator - Google Patents

Abstract

The invention discloses a turn-to-turn short circuit fault diagnosis method for a rotor winding of a brushless excitation generator. The turn-to-turn short circuit fault diagnosis method comprises the steps that the theoretical reactive power value Q of the brushless excitation generator under the normal state is reversely calculated, the reactive power relative deviation a% of the measured reactive power value Q' and the theoretical reactive power value Q of the brushless excitation generator is calculated, the reactive power relative deviation a% and the preset threshold value are compared, and whether a turn-to-turn short circuit fault of the rotor winding occurs or not is judged. By means of the turn-to-turn short circuit fault diagnosis method, the accuracy on the aspect of the detection of the turn-to-turn short circuit of the rotor winding of the brushless excitation generator is improved. The defect that excitation currents cannot be detected when an excitation current method is adopted for the brushless excitation generator is overcome, faults under any working condition can be detected, the size is judged, and the severity degree of the short circuit fault can be directly reflected. New mentoring points do not need to be increased, operation is easy and convenient, sensitivity is high, and cost is saved.

Description

A kind of brushless excitation generator rotor interturn short-circuit method for diagnosing faults

Technical field

The present invention relates to a kind of generator rotor interturn short-circuit method for diagnosing faults, especially a kind of brushless excitation generator rotor interturn short-circuit method for diagnosing faults, belongs to generator failure diagnostic techniques field.

Background technology

At present, the method for on-line checkingi rotor interturn short-circuit fault mainly contains detecting coil method, exciting current method and the detection method based on rotor fundamental vibration.

Detecting coil method carries out differential to the rotating magnetic field in electricity generator stator core air gap, then diagnoses rotor windings whether to there is the position of shorted-turn fault and fault groove by the waveform after analytic signal differential.But the method is only suitable for diagnosing the non salient pole machine of distributed winding and only could obtaining higher monitoring reliability in empty load of motor state, and when motor run with load, Effect on Detecting is also not obvious, and accuracy in detection is poor.

Exciting current method monitors rotor short-circuit fault according to the change of exciting current before and after short trouble, but the exciting current of brushless excitation system is immesurable, and the method is not suitable for brushless excitation generator.

Detection method based on the fundamental vibration of rotor is that the vibration signal by analyzing rotor carrys out detection failure, but rotor oscillation is the result of dynamo-electric cross action, comprise the impact of the original state such as mass unbalance and dynamic bias, this makes the fundamental vibration of short circuit generation rear motor still may be in normal range, cannot detect fault.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of brushless excitation generator rotor interturn short-circuit method for diagnosing faults.

The technical solution used in the present invention is:

A kind of brushless excitation generator rotor interturn short-circuit method for diagnosing faults, comprises the following steps:

Step 1: reactive power theory value Q under brushless excitation generator normal condition described in backwards calculation;

Step 2: the reactive power measured value Q calculating described brushless excitation generator ^'with the reactive power relative deviation a% of reactive power theory value Q:

$a\%=\frac{Q-Q^{\′}}{Q+U^2/x_d}---\left(1\right)$

Wherein U is stator voltage, x _dit is longitudinal axis synchronous reactance;

Step 3: if described reactive power relative deviation a% is greater than predetermined threshold value, judge that brushless excitation generator rotor windings exists shorted-turn fault; Otherwise, judge that brushless excitation generator rotor windings does not exist shorted-turn fault.

Described step 1 comprises step by step following:

Step 1-1: gather electric parameter when described brushless excitation generator normally runs, calculates generator excitation I when described brushless excitation generator normally runs _fd; Described electric parameter comprises the exciting current I of active-power P, reactive power Q, stator voltage U and exciter _f;

Step 1-2: set up described brushless excitation generator reactive power and calculate model Q (P, U, I _fd):

The exciting current I of active-power P when normally running with described brushless excitation generator, reactive power Q, stator voltage U and exciter _ffor input data, be export data with reactive power Q, matching reactive power calculates model Q (P, U, I _fd);

Step 1-3: reactive power Q when brushless excitation generator described in synchronous acquisition runs ^', active-power P ', the exciting current I ' of stator voltage U ' and exciter _f, calculate the exciting current I ' when described brushless excitation generator runs _fd;

Step 1-4: active-power P when described brushless excitation generator is run ', stator voltage U ' and exciting current I ' _fdbring reactive power into and calculate model Q (P, U, I _fd), calculate reactive power theory value Q when described brushless excitation generator runs.

Described step 1-2 uses reactive power described in neural network matching to calculate model Q (P, U, I _fd).

The beneficial effect adopting technique scheme to produce is:

1, after it utilizes generator amature winding generation turn-to-turn short circuit, effective magnetic field weakens, the feature that output reactive power reduces, adopts the criterion of reactive power relative deviation to carry out Fault Identification, improves brushless excitation generator rotor interturn short-circuit context of detection accuracy.

2, it judges brushless excitation generator rotor interturn short-circuit fault by the relative deviation of reactive power, compensate for exciting current immesurable defect when brushless excitation generator adopts exciting current method, can detect the fault under any operating mode, the size of criterion directly can reflect the order of severity of short trouble.

3, it need not increase new monitoring point, easy and simple to handle, highly sensitive, cost-saving.

Accompanying drawing explanation

Fig. 1 is process flow diagram of the present invention;

Fig. 2 is the process flow diagram of step 1 of the present invention.

Embodiment

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

Embodiment 1:

A kind of brushless excitation generator rotor interturn short-circuit method for diagnosing faults, comprises the following steps:

Step 1: reactive power theory value Q under brushless excitation generator normal condition described in backwards calculation;

Step 2: calculate the reactive power measured value Q ' of described brushless excitation generator and the reactive power relative deviation a% of reactive power theory value Q:

$a\%=\frac{Q-Q^{\′}}{Q+U^2/x_d}---\left(1\right)$

Wherein U is stator voltage, x _dit is longitudinal axis synchronous reactance;

Step 3: if described reactive power relative deviation a% is greater than predetermined threshold value, judge that brushless excitation generator rotor windings exists shorted-turn fault; Otherwise, judge that brushless excitation generator rotor windings does not exist shorted-turn fault.

Described step 1 comprises step by step following:

Step 1-1: gather electric parameter when described brushless excitation generator normally runs, calculates generator excitation I when described brushless excitation generator normally runs _fd; Described electric parameter comprises the exciting current I of active-power P, reactive power Q, stator voltage U and exciter _f;

Step 1-2: set up described brushless excitation generator reactive power and calculate model Q (P, U, I _fd):

The exciting current I of active-power P when normally running with described brushless excitation generator, reactive power Q, stator voltage U and exciter _ffor input data, be export data with reactive power Q, matching reactive power calculates model Q (P, U, I _fd);

Step 1-3: reactive power Q when brushless excitation generator described in synchronous acquisition runs ^', active-power P ', the exciting current I ' of stator voltage U ' and exciter _f, calculate the exciting current I ' when described brushless excitation generator runs _fd;

Step 1-4: active-power P when described brushless excitation generator is run ', stator voltage U ' and exciting current I ' _fdbring reactive power into and calculate model Q (P, U, I _fd), calculate reactive power theory value Q when described brushless excitation generator runs.

Described step 1-2 uses reactive power described in neural network matching to calculate model Q (P, U, I _fd).

Reactive power relative deviation a% size characterizes the degree of short circuit of rotor windings, and numerical value is larger, and degree of short circuit is more serious.

Consider the error in generator parameter and data acquisition, if the threshold value of the present embodiment is 4% a%> threshold value, brushless excitation generator generation rotor interturn short-circuit fault; If a%≤threshold value, brushless excitation generator is without rotor interturn short-circuit fault.

For brushless excitation generator, exciting current can not be surveyed, and generator excitation is that we can utilize the exciting current of the exciter that can survey by the excitation con-trol of exciter, according to exciter and commutation system mathematical model, calculate generator excitation under normal operation.Under normal condition, state (excitation, meritorious and terminal voltage one timing) is determined for a certain of generator, reactive power can be calculated and calculate standard value Q, then the actual measured value Q ' of it and reactive power is compared, judge whether rotor interturn short-circuit occurs by the rate of change of actual measured value corresponding standard value.

Assuming that the idle calculated value of Q, Q ' reactive power measurement value, I _fexciting current of exciter, I _fdexciter current of generator, P active power, U stator voltage, w _fdthe rotor windings number of turn, w ' _fdthe rotor windings residue number of turn, p power generator electrode logarithm, ψ synchronous motor each winding magnetic linkage matrix, each winding resistance matrix of R synchronous motor, each winding current matrix of I synchronous motor, ω motor speed, u _dstator winding voltage longitudinal axis component, u _qstator winding voltage quadrature component, u ₀stator winding voltage zero-axis component, u _fdrotor windings field voltage, ψ _dsynchronous motor stator winding longitudinal axis magnetic linkage, ψ _qsynchronous motor stator winding transverse axis magnetic linkage, ψ ₀synchronous motor stator winding zero axle magnetic linkage, ψ _fdsynchronous electric motor rotor winding magnetic linkage, ψ _1dequivalence longitudinal axis damping winding magnetic linkage, ψ _1qequivalence transverse axis damping winding magnetic linkage, i _dstator winding current longitudinal axis component, i _qstator winding current quadrature component, i ₀stator winding current zero-axis component, I _1dequivalence longitudinal axis damping winding electric current, I _1qequivalence transverse axis damping winding electric current, r stator winding resistance, R _fdfield copper resistance, R _1dequivalence longitudinal axis damping winding resistance, R _1qequivalence transverse axis damping winding resistance, x _dlongitudinal axis synchronous reactance, x _adthe longitudinal axis reactance of armature reaction, x _qquadrature-axis synchronous reactance, x _aqcross-magnetizing armature reaction reactance, x ₀zero axle synchronous reactance, x _ffdfield copper reactance, x _f1dfield copper and the mutual inductance of longitudinal axis damping winding resist, x _11dthe reactance of longitudinal axis damping winding, x _11qthe reactance of transverse axis damping winding, δ generator's power and angle, i _astator winding A phase current, i _bstator winding B phase current, i _cstator winding C phase current, E generator no-load electromotive force, L _adsynchronous motor longitudinal axis Armature inductance coefficient, M _afdtotal coefficient of mutual inductance of stator A phase winding and field copper, M _afd0total coefficient of mutual inductance maximal value of stator A phase winding and field copper, L _δstator self inductance base value, k _ifdstator current base value and rotor current base value ratio, i _δstator current base value, I _{fd δ}rotor current base value, τ motor pole span, l stator winding conductor bars in electrical machines effective length, a _sstator winding circuitry number, a _fdeach pole field copper circuitry number, k _{0 δ 1}stator winding fundamental wave winding coefficient, k _{0 δ fd1}field copper fundamental wave winding coefficient, λ _d11air-gap permeance coefficient, w stator winding circle, the output voltage after U ' generator rotor interturn short-circuit fault, the no-load electromotive force after E ' generator rotor interturn short-circuit fault, the merit angle after δ ' generator rotor interturn short-circuit fault.

Derivation based on the brushless excitation generator rotor interturn short-circuit fault diagnosis criterion of idle relative deviation is as follows:

Brushless excitation generator Park equation is: $U=\mathrm{p\ψ}+\mathrm{RI}+\mathrm{\ω}\left[\begin{array}{c}-{\mathrm{\ψ}}_q\\ {\mathrm{\ψ}}_d\\ 0\\ 0\\ 0\\ 0\end{array}\right]---\left(2\right)$

Wherein: $U=\left[\begin{array}{c}{u}_d\\ u_q\\ u_0\\ u_{\mathrm{fd}}\\ 0\\ 0\end{array}\right]\mathrm{\ψ}=\left[\begin{array}{c}{\mathrm{\ψ}}_d\\ {\mathrm{\ψ}}_q\\ {\mathrm{\ψ}}_0\\ {\mathrm{\ψ}}_{\mathrm{fd}}\\ {\mathrm{\ψ}}_{1d}\\ {\mathrm{\ψ}}_{1q}\end{array}\right]I=\left[\begin{array}{c}{i}_d\\ i_q\\ i_0\\ I_{\mathrm{fd}}\\ I_{1d}\\ I_{1q}\end{array}\right]R=\left[\begin{array}{cccccc}-r& 0& 0& 0& 0& 0\\ 0& -r& 0& 0& 0& 0\\ 0& 0& -r& 0& 0& 0\\ 0& 0& 0& R_{\mathrm{fd}}& 0& 0\\ 0& 0& 0& 0& R_{1d}& 0\\ 0& 0& 0& 0& 0& R_{1q}\end{array}\right]$

$\left[\begin{array}{c}{\mathrm{\ψ}}_d\\ {\mathrm{\ψ}}_q\\ {\mathrm{\ψ}}_0\\ {\mathrm{\ψ}}_{\mathrm{fd}}\\ {\mathrm{\ψ}}_{1d}\\ {\mathrm{\ψ}}_{1q}\end{array}\right]\left[\begin{array}{cccccc}-x_d& 0& 0& x_{\mathrm{ad}}& x_{\mathrm{ad}}& 0\\ 0& -x_q& 0& 0& 0& x_{\mathrm{aq}}\\ 0& 0& -x_0& 0& 0& 0\\ -x_{\mathrm{ad}}& 0& 0& x_{\mathrm{ffd}}& x_{f1d}& 0\\ -x_{\mathrm{ad}}& 0& 0& x_{f1d}& x_{11d}& 0\\ 0& -x_{\mathrm{aq}}& 0& 0& 0& x_{11q}\end{array}\right]\left[\begin{array}{c}{i}_d\\ i_q\\ i_0\\ I_{\mathrm{fd}}\\ I_{1d}\\ I_{1q}\end{array}\right]$

Assuming that generator bringing onto load under steady-state symmetrical condition runs, merit angle is δ, so there is boundary condition:

I _1d=0, I _1q=0, ω=1, ψ _d=constant, ψ _q=constant, u _d=Usin δ, u _q=Ucos δ

Substitution Park equation obtains:

u _d＝-ψ _q-ri _d＝x _qi _q-ri _d(3)

u _q＝ψ _d-ri _q＝E-x _di _d-ri _q(4)

$i_d=\frac{-{\mathrm{ru}}_d+x_q(E-u_q)}{r^2+x_d{x}_q}=\frac{-\mathrm{rU}\sin \mathrm{\δ}+x_q(E-U\cos \mathrm{\δ})}{r^2+x_d{x}_q}---\left(5\right)$

$i_q=\frac{x_d{u}_d+r(E-u_q)}{r^2+x_d{x}_q}=\frac{x_{d}U\sin \mathrm{\δ}+r(E-U\cos \mathrm{\δ})}{r^2+x_d{x}_q}---\left(6\right)$

In the synchronous generator of reality, the value of stator resistance r is general all very little, and therefore, above formula can be reduced to:

$i_d=\frac{E-U\cos \mathrm{\δ}}{x_d}---\left(7\right)$

$i_q=\frac{U\sin \mathrm{\δ}}{x_d}---\left(8\right)$

So result above brought into, synchronous generator active power of output and reactive power are respectively:

$P=u_d{i}_d+u_q{i}_q=\frac{\mathrm{EU}}{x_d}\sin \mathrm{\δ}+(\frac{1}{x_q}-\frac{1}{x_d})\frac{U^2}{2}\sin 2\mathrm{\δ}---\left(9\right)$

$Q=u_q{i}_d-u_d{i}_q=\frac{\mathrm{EU}}{x_d}\cos \mathrm{\δ}-(\frac{1}{x_q}+\frac{1}{x_d})\frac{U^2}{2}+(\frac{1}{x_q}-\frac{1}{x_d})\frac{U^2}{2}\cos 2\mathrm{\δ}---\left(10\right)$

If implicit pole synchronous motor, x _q=x _d, then:

$P=\frac{\mathrm{EU}}{x_d}\sin \mathrm{\δ}---\left(11\right)$

$Q=\frac{\mathrm{EU}}{x_d}\cos \mathrm{\δ}-\frac{U^2}{x_d}---\left(12\right)$

Generator no-load electromotive force:

E＝x _adI _fd(13)

Wherein:

x _ad＝L _ad＝M _afd(14)

$M_{\mathrm{afd}}=\frac{M_{\mathrm{afd}0}}{L_{\mathrm{\δ}}}\frac{1}{k_{\mathrm{ifd}}}---\left(15\right)$

$k_{\mathrm{ifd}}=\frac{i_{\mathrm{\δ}}}{I_{\mathrm{fd\δ}}}---\left(16\right)$

$M_{\mathrm{afd}0}=\frac{16\mathrm{\τlp}}{a_s{a}_{\mathrm{fd}}{\mathrm{\π}}^2}\left(w_{\mathrm{fd}}{k}_{0\mathrm{\δfd}1}\right)\left(\frac{w}{2p}{k}_{0\mathrm{\δ}1}\right){\mathrm{\λ}}_{d11}---\left(17\right)$

Bring formula (13) ~ formula (16) into formula (12), obtaining generator no-load electromotive force is:

$E=\frac{16\mathrm{\τlp}}{L_{\mathrm{\δ}}{k}_{\mathrm{ifd}}{a}_s{a}_{\mathrm{fd}}{\mathrm{\π}}^2}\left(w_{\mathrm{fd}}{k}_{0\mathrm{\δfd}1}\right)\left(\frac{w}{2p}{k}_{0\mathrm{\δ}1}\right){\mathrm{\λ}}_{d11}---\left(18\right)$

Formula (17) is brought into formula (11) to obtain generator and export idle and rotor number of turn relation:

$Q={\mathrm{aw}}_{\mathrm{fd}}\frac{U}{x_d}\cos \mathrm{\δ}-\frac{U^2}{x_d}---\left(19\right)$

Wherein:

$a=\frac{16\mathrm{\τlp}}{L_{\mathrm{\δ}}{k}_{\mathrm{ifd}}{a}_s{a}_{\mathrm{fd}}{\mathrm{\π}}^2}{k}_{0\mathrm{\δfd}1}\left(\frac{w}{2p}{k}_{0\mathrm{\δ}1}\right){\mathrm{\λ}}_{d11}---\left(20\right)$

If rotor windings generation turn-to-turn short circuit, then idle output becomes:

$\begin{array}{c}{Q}^{\′}=\frac{E^{\′}{U}^{\′}}{x_d}\cos {\mathrm{\δ}}^{\′}-\frac{U^{\′2}}{x_d}=\frac{16\mathrm{\τlp}}{L_{\mathrm{\δ}}{k}_{\mathrm{ifd}}{a}_s{a}_{\mathrm{fd}}{\mathrm{\π}}^2}\left(w_{\mathrm{fd}}^{\′}{k}_{0\mathrm{\δfd}1}\right)\left(\frac{w}{2p}{k}_{0\mathrm{\δ}1}\right){\mathrm{\λ}}_{d11}\frac{U^{\′}}{x_d}\cos {\mathrm{\δ}}^{\′}-\frac{U^{\′2}}{x_d}\\ =a{w}_{\mathrm{fd}}^{\′}\frac{U^{\′}}{x_d}\cos {\mathrm{\δ}}^{\′}-\frac{U^{\′2}}{x_d}\end{array}---\left(21\right)$

In formula, adding slash amount is generator value after rotor windings generation turn-to-turn short circuit.

Rotor windings number of turn expression formula before and after generator generation rotor interturn short-circuit fault is obtained through conversion:

$w_{\mathrm{fd}}=\frac{{\mathrm{Qx}}_d}{a\cos \mathrm{\δU}}+\frac{U}{a\cos \mathrm{\δ}}---\left(21\right)$

$w_{\mathrm{fd}}^{\′}=\frac{Q^{\′}{x}_d}{a\cos {\mathrm{\δ}}^{\′}U}+\frac{U^{\′}}{a\cos {\mathrm{\δ}}^{\′}}---\left(22\right)$

After rotor windings generation shorted-turn fault, degree of short circuit criterion is:

$a\%=\frac{w_{\mathrm{fd}}-w_{\mathrm{fd}}^{\′}}{w_{\mathrm{fd}}}=\frac{\frac{{\mathrm{Qx}}_d}{a\cos \mathrm{\δU}}+\frac{U}{a\cos \mathrm{\δ}}-(\frac{Q^{\′}{x}_d}{a\cos {\mathrm{\δ}}^{\′}{U}^{\′}}+\frac{U^{\′}}{a\cos {\mathrm{\δ}}^{\′}})}{\frac{Q{x}_d}{a\cos \mathrm{\δU}}+\frac{U}{a\cos \mathrm{\δ}}}---\left(23\right)$

Because generator connecting in parallel with system runs, generator port voltage remains unchanged before and after rotor interturn short-circuit fault:

$a\%=\frac{w_{\mathrm{fd}}-w_{\mathrm{fd}}^{\′}}{w_{\mathrm{fd}}}=\frac{Q-Q^{\′}}{Q+\frac{U^2}{x_d}}---\left(24\right)$

Formula (24) is exactly the brushless excitation generator rotor interturn short-circuit fault diagnosis new criterion based on idle relative deviation, this criterion is slightly more a little bit smaller than idle change relative value, illustrate that Short Circuit Between Generator Rotor Windings fault causes idle change larger, if salient pole generator, idle formula is exported according to generator, compare with non-salient pole machine, criterion is more a little bit smaller than idle relative value.The saturated impact of generator field is not considered in addition in the process of pushing over, because the saturated meeting in magnetic field causes magnetic density relatively to reduce, idle output will reduce, therefore this criterion numerical value can affect by it, if generator is underexcited operation, impact does not almost have, if excessively encourage, influence degree increases with degree of excessively encouraging and increases.This criterion has also been adapted to brush excitation generator in addition.

In the present embodiment, brushless excitation generator is normally incorporated into the power networks under state, active power remains on about 18%, change field copper turn-to-turn short circuit degree, degree of short circuit is increased to 20% successively from 0, verify validity of the present invention, generator electrical state monitoring amount online record data when stator current is 20A and result of calculation are in table 1.Visible criterion calculated value a% is close with experiment short circuit number of turn number percent, demonstrates accuracy of the present invention.

Table 1

Claims (3)

1. a brushless excitation generator rotor interturn short-circuit method for diagnosing faults, is characterized in that: comprise the following steps:

Step 1: reactive power theory value Q under brushless excitation generator normal condition described in backwards calculation;

Step 2: calculate the reactive power measured value Q ' of described brushless excitation generator and the reactive power relative deviation a% of reactive power theory value Q:

$a\%=\frac{Q-Q^{\′}}{Q+U^2/x_d}---\left(1\right)$

Wherein U is stator voltage, x _dit is longitudinal axis synchronous reactance;

Step 3: if described reactive power relative deviation a% is greater than predetermined threshold value, judge that brushless excitation generator rotor windings exists shorted-turn fault; Otherwise, judge that brushless excitation generator rotor windings does not exist shorted-turn fault.

2. brushless excitation generator rotor interturn short-circuit method for diagnosing faults according to claim 1, is characterized in that: described step 1 comprises step by step following:

Step 1-1: gather electric parameter when described brushless excitation generator normally runs, calculates generator excitation I when described brushless excitation generator normally runs _fd; Described electric parameter comprises the exciting current I of active-power P, reactive power Q, stator voltage U and exciter _f;

Step 1-2: set up described brushless excitation generator reactive power and calculate model Q (P, U, I _fd):

The exciting current I of active-power P when normally running with described brushless excitation generator, reactive power Q, stator voltage U and exciter _ffor input data, be export data with reactive power Q, matching reactive power calculates model Q (P, U, I _fd);

Step 1-3: the exciting current I ' of reactive power Q ', active-power P ', stator voltage U ' and exciter when brushless excitation generator described in synchronous acquisition runs _f, calculate the exciting current I ' when described brushless excitation generator runs _fd;

Step 1-4: active-power P when described brushless excitation generator is run ', stator voltage U ' and exciting current I ' _fdbring reactive power into and calculate model Q (P, U, I _fd), calculate reactive power theory value Q when described brushless excitation generator runs.

3. brushless excitation generator rotor interturn short-circuit method for diagnosing faults according to claim 2, is characterized in that: described step 1-2 uses reactive power described in neural network matching to calculate model Q (P, U, I _fd).