CN109991539B - Method and system for detecting one-phase open circuit of rotating diode of multiphase angle connection brushless exciter - Google Patents
Method and system for detecting one-phase open circuit of rotating diode of multiphase angle connection brushless exciter Download PDFInfo
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Abstract
The application relates to a method and a system for detecting one-phase open circuit of a rotating diode of a multi-phase angle-connection brushless exciter. The method comprises the steps of obtaining exciting current entering a stator exciting winding of an exciter, filtering out direct-current components and phase number frequency multiplication components in the exciting current to obtain current simultaneously containing odd-number harmonics and even-number harmonics, dividing the current simultaneously containing the odd-number harmonics and the even-number harmonics into two paths to obtain first current and second current, delaying the second current for reference time to obtain first delayed exciting current, subtracting the first current from the first delayed exciting current to obtain current containing odd-number harmonics, and performing rotary diode one-phase open circuit detection according to the current simultaneously containing the odd-number harmonics and the current containing the odd-number harmonics. The method can not only realize accurate fault judgment, but also does not need additional devices, does not need to modify a motor structure, reduces the process difficulty and cost, and has high detection reliability.
Description
Technical Field
The application relates to the technical field of exciters, in particular to a method and a system for detecting one-phase open circuit of a rotating diode of a multi-phase angle-connection brushless exciter.
Background
The excitation system is the basis for ensuring the safety of the generator and the stable operation of the power system, compared with static excitation, the brushless excitation system cancels the carbon brush and the slip ring of the generator, thereby obviously improving the reliability of the excitation system and being the preferred excitation mode of the high-capacity nuclear power unit. The multiphase angle-connection brushless exciter can reduce the requirement of a high-power excitation system on the capacity of a single diode, can improve the quality of rectified voltage and the fault tolerance of the system, and is widely applied, but a rotary rectifier in the multiphase angle-connection brushless exciter is in a high-speed rotation state, the diode is easily damaged during operation, the exciter still can provide normal current for a main generator at the initial stage of open circuit fault, if the fault is left to be deteriorated, the normal operation of the main generator is seriously influenced, serious consequences are caused, and the monitoring of the state of the diode is very difficult because the diode is in the high-speed rotation state during operation.
The traditional fault detection method for the rotating rectifier is a Hall element detection method, whether faults exist or not is judged by detecting whether the current of each phase of the rotating rectifier exists in fixed time, however, the method cannot detect diode damage when a fuse is not fused, a probe of a Hall element sensor is easy to deteriorate, misoperation is easy to occur during detection, accuracy of a detection result is affected, and the traditional fault detection method for the rotating rectifier is low in reliability.
Disclosure of Invention
Therefore, it is necessary to provide a method and a system for detecting a one-phase open circuit of a rotating diode of a multiphase angular contact brushless exciter to solve the problem of low reliability of the conventional fault detection method for the rotating rectifier.
A method for detecting one-phase open circuit of a rotating diode of a multi-phase angle-connection brushless exciter comprises the following steps:
obtaining the exciting current entering a stator exciting winding of an exciter;
filtering out direct current components and phase frequency multiplication components in the exciting current to obtain current containing odd harmonics and even harmonics;
dividing the current containing odd harmonics and even harmonics into two paths to obtain a first current and a second current, and delaying the second current by reference time to obtain a first delayed exciting current;
subtracting the first current from the first delayed excitation current to obtain a current containing odd harmonics;
and detecting the one-phase open circuit of the rotating diode according to the current containing odd harmonics and even harmonics and the current containing odd harmonics.
A polyphase angular joint brushless exciter rotating diode one-phase open circuit detection system comprises an acquisition device and a processing device, wherein the acquisition device is connected with the processing device and is connected with a stator exciting winding of an exciter;
the collecting device is used for obtaining exciting current entering a stator exciting winding of an exciter, the processing device is used for obtaining exciting current entering the stator exciting winding of the exciter, filtering direct current components and phase number frequency multiplication components in the exciting current to obtain current simultaneously containing odd harmonics and even harmonics, dividing the current simultaneously containing the odd harmonics and the even harmonics into two paths to obtain first current and second current, delaying the second current for reference time to obtain first delayed exciting current, subtracting the first current from the first delayed exciting current to obtain current containing odd harmonics, and performing rotating diode one-phase open circuit detection according to the current simultaneously containing the odd harmonics and the even harmonics and the current containing the odd harmonics.
According to the method and the system for detecting the one-phase open circuit of the rotating diode of the multiphase angular contact brushless exciter, the obtained exciting current entering the stator exciting winding of the exciter is processed to obtain the current simultaneously containing odd harmonics and even harmonics and the current containing the odd harmonics. The current containing odd harmonics and even harmonics and the current containing odd harmonics are analyzed, the current containing even harmonics is extracted to be used as a fault judgment basis, and the fault detection of the one-phase open circuit of the rotating diode of the multiphase angular connection brushless exciter can be carried out.
Drawings
FIG. 1 is a flow chart of a method for detecting a one-phase open circuit of a rotating diode of a multi-phase angle-coupled brushless exciter according to one embodiment;
FIG. 2 is a diagram of a stator field winding and rotating diodes in accordance with one embodiment;
FIG. 3 is a diagram of rotor armature potential and armature current waveforms with one phase open for the rotating diodes of the brushless exciter in one embodiment;
FIG. 4 is a graph of current magnitude resulting from a phase open fault in one embodiment;
FIG. 5 is a flow chart of a method for detecting a one-phase open circuit of a rotating diode of a multi-phase angle-coupled brushless exciter according to another embodiment;
FIG. 6 is a current waveform diagram of the entire transient process before and after a phase open circuit fault of a 11-phase brushless excitation system diode in one embodiment;
FIG. 7 is a current waveform diagram illustrating a phase open circuit fault of a rotating diode of an 11-phase brushless excitation system according to an embodiment;
FIG. 8 is a current waveform diagram of the entire transient process before and after a one-phase open circuit fault of a 39-phase brushless excitation system diode in one embodiment;
FIG. 9 is a current waveform diagram illustrating a one-phase open circuit fault of a rotating diode of a 39-phase brushless excitation system in accordance with an embodiment;
FIG. 10 is a flow chart of a method for detecting a one-phase open circuit of a rotating diode of a polyphase angular contact brushless exciter in accordance with still another embodiment;
FIG. 11 is a flow chart of a method for detecting a one-phase open circuit of a rotating diode of a multi-phase angle-coupled brushless exciter in accordance with another embodiment;
FIG. 12 is a flow diagram of a method for detecting a one-phase open circuit of a rotating diode of a multi-phase angle-coupled brushless exciter in accordance with one embodiment;
fig. 13 is a block diagram of a system for detecting a one-phase open circuit of a rotating diode of a multi-phase angle-coupled brushless exciter according to an embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described more fully below by way of examples in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In one embodiment, a method for detecting a one-phase open circuit of a rotating diode of a multi-phase angle-connected brushless exciter is provided, referring to fig. 1, comprising the steps of:
step S100: the excitation current entering the stator field winding of the exciter is obtained.
The stator field winding, also called an armature, is a component for generating electromotive force. When the multi-phase angle-connection brushless exciter works, a certain excitation current is supplied to the multi-phase angle-connection brushless exciter by an exciting device to generate a constant magnetic field, a stator exciting winding rotates and cuts the generated magnetic field to induce electromotive force, the stator exciting winding is connected with a rotary diode in a connecting mode shown in figure 2, and the rotary diode is used for converting alternating current electromotive force induced by the stator exciting winding into direct current electromotive force and then supplying the direct current electromotive force to a generator for excitation, so that the multi-phase angle-connection brushless exciter is a preferred excitation mode of a nuclear power unit. When the multi-phase angle-connection brushless exciter normally operates, the potential and the current waveform of each phase of armature are the same, when one-phase open circuit fault occurs to a rotating diode of the multi-phase angle-connection brushless exciter, the potential and the current of the armature can be caused to change, after the current entering a stator exciting winding is synchronously sampled at a stator end of the multi-phase angle-connection brushless exciter, whether one-phase open circuit fault occurs to the rotating diode of the multi-phase angle-connection brushless exciter or not can be detected through the analysis of exciting current, the original structure of the exciter does not need to be changed, and the cost is reduced.
Step S200: and filtering a direct current component and a phase number frequency multiplication component in the exciting current to obtain the current simultaneously containing odd-order and even-order harmonics.
The excitation current comprises a direct current component, a phase multiple reference frequency component, a current containing even harmonics and a current containing odd harmonics, the phase multiple reference frequency component has a larger value when the brushless exciter normally operates, the current containing the even harmonics and the current containing the odd harmonics do not cause a diode one-phase open circuit fault, but the current containing the even harmonics and the current containing the odd harmonics comprise diode fault characteristic quantities, but the amplitude is lower than that of the direct current component and the phase multiple reference frequency component.
Step S300: the current containing odd harmonics and even harmonics is divided into two paths to obtain a first current and a second current, and the second current is delayed for reference time to obtain a first delayed exciting current.
The mode of collecting the low-order harmonic current in the current simultaneously containing odd-order and even-order harmonics is not unique, in one embodiment, the current simultaneously containing odd-order and even-order harmonics can be divided into two paths to obtain a first current and a second current, the second current is delayed for a reference time to obtain a first delayed excitation current, the first delayed excitation current simultaneously contains the original part and the delayed part of the current simultaneously containing odd-order and even-order harmonics, the characteristic part can be separated from the original part of the current simultaneously containing odd-order and even-order harmonics, and the processing is more convenient.
Step S400: and subtracting the first current from the first delayed excitation current to obtain a current containing odd harmonics.
Because the first delayed exciting current contains the original part and the delayed part of the current of odd harmonics and even harmonics simultaneously, the non-characteristic part in the current containing odd harmonics and even harmonics simultaneously can be filtered out by subtracting the delayed exciting current from the delayed exciting current, the influence of the non-characteristic part on the detection result is reduced, the current containing odd harmonics is obtained, and the low harmonic component in the exciting current is better extracted.
Step S500: and detecting the one-phase open circuit of the rotating diode according to the current containing odd harmonics and even harmonics and the current containing odd harmonics.
Considering that even harmonic components (phase-dividing frequency-multiplication components) in stator exciting current are all caused by diode one-phase open-circuit faults, the current containing odd-order and even-order harmonics and the current containing odd-order harmonics are analyzed, and the current containing even-order harmonics is extracted as a fault judgment basis, so that an effective way is provided for monitoring and protecting the diode one-phase open-circuit faults.
Specifically, referring to fig. 2, assuming that a phase 2 bridge arm has an open-circuit fault, only the armature currents of the 1 st and 2 nd phases are affected first, and the armature currents of the remaining phases are the same as those in normal operation. After a phase open circuit fault occurs, the 1 st phase potential and the 2 nd phase potential of the armature winding are connected in series and jointly act on the 1 st bridge arm to conduct the armature winding, so that the 1 st phase armature winding and the 2 nd phase armature winding always flow the same current after the fault.
Under normal operation, the armature potentials and currents of the phases are sequentially different by 2n pi/m (n is 1,2,3, …) electrical angle, and the 1 st and 2 nd phase armature potentials and currents can be written as follows:
after the fault, the induced voltage of each phase of armature is unchanged, and the combined potential of the 1 st phase and the 2 nd phase is as follows:
after the fault, the current of the 1 st phase armature lags behind n pi/m compared with the normal state, the current of the 2 nd phase armature leads n pi/m compared with the normal state, and the expressions of the currents of the 1 st phase armature and the 2 nd phase armature after the fault are as follows:
fig. 3 shows the rotor armature potential and armature current waveforms for a phase open circuit fault of the polyphase angular contact brushless exciter rotating diodes. Regarding the armature currents of the 1 and 2 phases after the 2 nd phase bridge arm has an open-circuit fault as the armature currents of the 1 and 2 phases and the delta i in normal operation1,Δi2By superposition of, i.e.
The armature reaction magnetomotive force of the 1 and 2 phases in fault operation is the armature reaction magnetomotive force and delta i generated by the 1 and 2 phase currents in normal operation1,Δi2Superposition of the generated magnetomotive force. Since only the armature currents of the two phases 1 and 2 are changed, only Δ i needs to be considered1,Δi2The generated synthetic magnetomotive force can complete the analysis of the armature reaction magnetomotive force under the open-circuit fault of the 2 nd phase bridge arm. Please refer to FIG. 4, Δ i1,Δi2Can be expressed as:
for Δ i1Fourier analysis is carried out to obtain
Δi1＝c0+Σ(akcoskωt+bksinkωt)k＝1,2,3,... (7)
Wherein:
for Δ i2Fourier analysis, we can obtain:
Δi2＝c0+Σ(akcoskωt+bksinkωt)k＝1,2,3,... (9)
wherein:
the current Δ i can be seen1,Δi2The filter does not contain direct current components and even harmonic components, and only contains fundamental wave components and odd harmonic components. These current components produce fractional and integer space harmonic magnetomotive forces, the sum of induced potentials in the stator excitation winding of the fractional and even harmonic magnetic fields is zero, and the electromotive force frequency induced in the stator winding by the fundamental wave and the odd space harmonic magnetomotive force is mainly analyzed.
Fundamental and odd (k 1,3, 5..) harmonic currents in the armature windings produce fundamental and odd (j 1,3, 5..) spatial harmonic magnetomotive forces. For the j-th harmonic magnetomotive force, the number of the pole pairs is j times of the fundamental wave, but the rotating speed is k/j times of the fundamental wave. The positive rotation component is k/j-1 times of the rotation speed of the stator, and the electromotive force frequency induced in the stator is k-j times of the fundamental wave. In the same way, the reverse rotation component is k/j +1 times of the rotation speed of the stator, and the electromotive force frequency induced in the stator is k + j times of the fundamental wave. That is, j-order space harmonic magnetomotive force generated by k-order harmonic current in the armature winding can induce harmonic current with even-numbered frequency multiplication such as 2, 4 and the like in the stator exciting winding, and the fault protection design can be carried out by utilizing the even-order harmonic current in the stator exciting current.
According to the method for detecting the one-phase open circuit of the rotating diode of the multiphase angular contact brushless exciter, the obtained exciting current entering the stator exciting winding of the exciter is processed to obtain the current simultaneously containing odd harmonics and even harmonics and the current containing the odd harmonics. The current containing odd harmonics and even harmonics and the current containing odd harmonics are analyzed, the current containing even harmonics is extracted to be used as a fault judgment basis, and the fault detection of the one-phase open circuit of the rotating diode of the multiphase angular connection brushless exciter can be carried out.
In one embodiment, referring to fig. 5, step S200 includes steps S210 to S230.
Step S210: the exciting current is divided into two paths to obtain a first exciting current and a second exciting current.
The manner of filtering the dc component and the phase frequency multiplication component in the exciting current is not unique, and in one embodiment, the exciting current may be divided into two paths to obtain a first exciting current and a second exciting current, and after the exciting current is divided into two paths, not only the portion originally included in the exciting current may be retained, but also other processing may be performed on the exciting current passing through the other path, so as to achieve the purpose of filtering the dc component and the phase frequency multiplication component.
Step S220: and delaying the second excitation current for a reference time to obtain a second delayed excitation current.
The second excitation current is delayed for reference time to obtain second delayed excitation current, the second delayed excitation current comprises the original part and the delayed part of the second excitation current, and the characteristic part can be separated from the original part of the second excitation current, so that the processing is more convenient.
Step S230: and subtracting the first exciting current from the second delayed exciting current, filtering out a direct-current component and a phase number frequency multiplication component in the exciting current, and obtaining a current simultaneously containing odd-order and even-order harmonics, wherein the reference time is the quotient of the reference time and the phase number of the exciter.
The number of phases of the exciter is not exclusive, as long as it is greater than 1. Because the second delayed exciting current comprises the original part and the delayed part of the second exciting current, the direct current component and the phase number frequency multiplication component in the second exciting current can be filtered by subtracting the delayed exciting current from the delayed exciting current, so that the current simultaneously containing odd harmonics and even harmonics is obtained, the influence of the direct current component and the phase number frequency multiplication reference frequency component in the exciting current on the detection result is reduced, and the low harmonic component in the exciting current is better extracted.
In one embodiment, the reference time is the inverse of twice the exciter field current frequency. Specifically, when the exciter exciting current frequency is f0When the reference time is
The reference time is
In this embodiment, the excitation current is set as:
in the formula: i isfd0Is the direct current quantity of the stator exciting current; k is the stator exciting current harmonic frequency;
respectively is an effective value and a phase angle of the k-th harmonic of the stator exciting current; omega0＝2πf0For synchronous angular velocity, wherein f0Is the synchronization frequency.
If the stator exciting current subharmonic is shifted to the right by 1/(2mf0) in the t-axis direction, then:
subtracting the two expressions (11) and (12) to obtain:
from the above formula can be seenThe stator exciting current is subtracted from the waveform of the stator exciting current which is shifted to the right in the t-axis direction by 1/(2mf0) to obtain a current i1The current does not contain direct current and multiple harmonics of 2m, but odd harmonics and even harmonics are retained, and the current containing the odd harmonics and the even harmonics is obtained.
The specific process of dividing the current simultaneously containing odd harmonics and even harmonics into two paths to obtain a first current and a second current, delaying the second current by reference time to obtain a first delayed exciting current, and subtracting the first delayed exciting current from the first current to obtain the current containing odd harmonics is as follows:
the current containing both odd and even harmonics is shifted to the right by 1/(2f0) in the direction of the t-axis, when:
subtracting the formulas (13) and (14) to obtain;
from the above formula, the current i2The fundamental wave and odd harmonic components are reserved, namely the current containing the odd harmonic. When a one-phase open-circuit fault of the diode occurs, the amplitude of an even harmonic of the exciting current is obviously increased, the current containing the odd harmonic and the even harmonic and the current containing the odd harmonic are analyzed, the current containing the even harmonic is extracted to be used as a fault judgment basis, the one-phase open-circuit fault detection of the rotating diode of the multiphase angular connection brushless exciter can be carried out, and the reliability is high.
Taking an 11-phase angle brushless excitation system and a 39-phase angle brushless excitation system as examples, fig. 6 and 7 show stator excitation current waveforms of the 11-phase angle brushless excitation machine, fig. 6 shows waveforms of the whole transition process before and after a fault, when a diode has a one-phase open circuit fault when t is 10s, then the waveform of t <10s represents a normal steady-state operation state before the fault, the waveform of t >10s represents the transition process after the fault, and fig. 7 represents a steady-state waveform after the fault (the same below). Fourier analysis is carried out on the stator exciting current steady-state current before and after the fault, and the result is shown in table 1.
TABLE 1
Similarly, fig. 8 and 9 show the stator field current waveform of a 39 phase angle brushless exciter with a 5s fault time, and the results of fourier analysis of this current are shown in table 2.
TABLE 2
As can be seen from tables 1 and 2, after a phase-one open circuit fault of a diode occurs in the brushless excitation system, the stator excitation current contains large even harmonic components of 2, 4, 6 and the like, the harmonics are all caused by the phase-one open circuit fault of the diode, and fault monitoring and protection can be performed based on the harmonics.
In one embodiment, referring to fig. 10, step S500 includes steps S510 to S530.
Step S510: and obtaining the current steady-state effective value simultaneously containing odd harmonics and even harmonics according to the current simultaneously containing odd harmonics and even harmonics.
The current containing odd harmonics and even harmonics is a value with the size and the direction changing according to a sine rule, and is a changed instantaneous value, and the current steady-state effective value containing the odd harmonics and the even harmonics refers to the electric energy consumed by the current containing the odd harmonics and the even harmonics in one period, so that the current containing the odd harmonics and the even harmonics can be accurately and stably represented.
Step S520: and obtaining the current steady-state effective value containing the odd harmonics according to the current containing the odd harmonics.
The current containing odd harmonics is a value with the size and the direction changing according to a sine rule and is a changing instantaneous value, and the current steady-state effective value containing the odd harmonics refers to the electric energy consumed by the current containing the odd harmonics in one period, so that the size of the current containing the odd harmonics can be accurately and stably represented.
Step S530: and detecting the one-phase open circuit of the rotating diode according to the current steady-state effective value containing odd harmonics and even harmonics and the current steady-state effective value containing odd harmonics.
The current steady state effective value containing odd harmonics and even harmonics represents the root mean square value of the current containing odd harmonics and even harmonics in a period, the current steady state effective value containing odd harmonics represents the root mean square value of the current containing odd harmonics in a period, and the detection error caused by current mutation can be effectively reduced by taking the current steady state effective value containing odd harmonics and even harmonics as the basis for fault judgment. It is understood that in other embodiments, the currents containing odd harmonics and the currents containing both odd harmonics and even harmonics may be further processed as the basis for determining the one-phase open circuit of the rotating diodes of the multiphase angular contact brushless exciter, as long as the skilled person can realize the judgment.
In one embodiment, referring to fig. 11, step S510 includes step S511 and step S512.
Step S511: the mean of the sum of the squares of the current in one current cycle is obtained, containing both odd and even harmonics.
Step S512: and acquiring the arithmetic square root of the mean value of the square sum to obtain the current steady-state effective value containing odd harmonics and even harmonics.
Specifically, steps S511 and S512 include:
wherein, I1Representing steady-state effective values of current containing both odd and even harmonics, i1Representing a current containing both odd and even harmonics, T representing the period of the excitation current, and T representing the sampling time to obtain the excitation current. The steady-state effective value of the current containing both odd harmonics and even harmonics can be obtained from the equation (16) based on the current containing both odd harmonics and even harmonics. It is understood that in other embodiments, T may be other time values set by the user according to the requirement, as long as the implementation is considered by those skilled in the art.
In one embodiment, referring to fig. 11, step S520 includes step S521 and step S522.
Step S521: the average of the sum of squares of currents containing odd harmonics over one current period is taken.
Step S522: and obtaining the arithmetic square root of the mean value of the square sum to obtain the current steady-state effective value containing odd harmonics.
Specifically, steps S521 and S522 include:
wherein, I2Representing steady-state effective values of currents containing odd harmonics i2Indicating the current containing odd harmonics, T indicating the period of the excitation current, and T indicating the sampling time for obtaining the excitation current. From equation (17), a current steady-state effective value containing odd harmonics can be obtained from a current containing odd harmonics. It is understood that in other embodiments, T may be other time values set by the user according to the requirement, as long as the implementation is considered by those skilled in the art.
In one embodiment, referring to fig. 11, step S530 includes step S531 and step S532.
Step S531: and acquiring the ratio of the current steady-state effective value containing odd harmonics and even harmonics and the current steady-state effective value containing odd harmonics.
After a one-phase open circuit fault of the diode occurs in the brushless excitation system, the stator excitation current contains larger even harmonic components such as 2, 4 and 6, and the harmonics are all caused by the one-phase open circuit fault of the diode. In theory, these harmonics can be selected for fault monitoring and protection, but have the following problems: the stator exciting current even harmonic wave is obviously increased after the one-phase open circuit fault of the rotary rectifier, and if the fault is judged by only taking the steady-state effective value of the even harmonic wave as a threshold value, the fault is difficult to distinguish from the one-tube fault of the rotary rectifier and the internal fault of the motor. In addition, before and after the fault occurs, the stator exciting current does not contain fundamental wave and odd harmonic component theoretically, but the exciter has low fundamental wave and odd harmonic current component due to the manufacturing error of the motor during normal operation, and the exciting current harmonic component with frequency multiplied by phase number has a large value during normal operation, is not caused by the open circuit fault of the diode phase, and needs to be considered during the fault protection design.
Considering that even harmonic components (except for phase frequency components) in stator exciting current are all caused by diode one-phase open-circuit faults, the ratio of current steady-state effective values containing odd-number harmonics and even-number harmonics in exciting current of a stator of an exciter to current steady-state effective values containing odd-number harmonics is obtained, the value of the ratio is lower no matter whether the exciter normally operates or one-tube open-circuit faults or other internal faults occur, and when the brushless exciter rotates a diode to generate the one-phase open-circuit faults, the ratio is higher, so that the ratio is used as the basis of fault protection judgment, the one-phase open-circuit faults and other faults of the diode can be distinguished, the reliability is high, and an effective way is provided for monitoring and protecting the one-phase open-circuit faults of the diode.
Step S532: and when the ratio is above a preset threshold value, judging that the rotating diode of the exciter has a one-phase open-circuit fault.
The preset threshold is a threshold which is determined by a user before fault detection, the value of the preset threshold is not unique, the values of the preset threshold are different under different conditions according to different types of brushless exciters, and for the same type of brushless exciter, the preset threshold can be adjusted according to actual requirements due to different working environments or other conditions, so long as the preset threshold can be realized by a person skilled in the art.
In one embodiment, the preset threshold is 1000. Specifically, taking 11-phase and 39-phase brushless excitation systems as examples, table 3 shows i obtained when 11-phase and 39-phase brushless excitation systems obtained by the method described in the above embodiment normally operate and when one phase of the diode is open-circuited1And i2Ratio of effective values, wherein i1For currents containing both odd and even harmonics, i2Currents containing odd harmonics.
TABLE 3
As can be seen from Table 3, i1And i2The ratio of effective values can reflect the characteristics brought by the one-phase open-circuit fault of the diode, and can be distinguished from the normal operation of the exciter, the one-tube open-circuit fault of the rotating rectifier and the internal fault of the exciter, and the fault operation is carried out1And i2The ratio of the effective values is more than 1000, which shows that the method for detecting the one-phase open circuit of the rotating diode of the multiphase angular contact brushless exciter can detect the one-phase open circuit fault of the rotating diode and has high reliability.
In one embodiment, step S400 may be implemented by step S410.
Step S410: and subtracting the first current and the first delayed exciting current by an inverted addition circuit or a differential circuit to obtain the current containing odd harmonics.
Specifically, the manner of performing the operation of subtracting the first current and the first delayed excitation current is not exclusive, and for example, the first current and the first delayed excitation current may be subtracted by an inverted addition circuit or a difference circuit to obtain a current including odd harmonics. The inverse adder circuit is also called as a differential input arithmetic circuit, when the inverse adder circuit is used for calculation, the subtraction of the first current and the first delayed exciting current is respectively input into the non-inverting input end and the inverting input end, the inverse adder circuit firstly realizes the inverse of the signal connected to the inverting input end and then carries out addition operation, so that the action of subtracting the first current and the first delayed exciting current is realized. The differential circuit is an amplifying circuit combining an inverting input and a non-inverting input, under the ideal operational amplification condition, the circuit is regarded as a virtual short phenomenon, the differential circuit can be used for realizing subtraction of two voltages, and the differential circuit is simple to manufacture and low in cost.
In order to better understand the above embodiments, a detailed explanation is given below with respect to one embodiment. In one embodiment, referring to fig. 12, first, the field current in the stator field winding is sampled at the brushless exciter end, and the sampled data is sent to the computer, and then the collected current is divided into two paths, one path of current ifdThe collected current is directly sent to an adder, and the other current i'fdThe collected current is passed through a 1/(2 mf)0) Sending the time delay circuit of second to an adder, wherein m is the phase number of the armature winding of the exciter, f0For rated frequency of brushless exciter, adder adds two currents ifd、i′fdSubtracting to obtain current i containing odd-order harmonic components and even-order harmonic components (except 2m frequency multiplication quantity)1Dividing the obtained current into two paths, wherein one path of current is to divide i into two paths1Directly sent to an adder, and another current i'1Is to mix i1Through a 1/(2 f)0) The second time delay circuit is sent to an adder, and the adder adds two paths of current i1、i′1Subtracting to obtain a current i containing only odd harmonic components2And the current i is obtained according to the following formula1、i2Effective value of steady state of1、I2：
Wherein: t is the period of the current, T is the time, T is P/f0P is the number of pole pairs;
when in use
And judging that the rotary rectifier has a phase open circuit fault.
In an embodiment, a system for detecting a one-phase open circuit of a rotating diode of a multiphase angular contact brushless exciter is provided, referring to fig. 13, including an acquisition device 110 and a processing device 120, where the acquisition device 110 is connected to the processing device 120, the acquisition device 110 is connected to a stator field winding of the exciter, the acquisition device 110 is configured to acquire a field current entering the stator field winding of the exciter, the processing device 120 is configured to acquire a field current entering the stator field winding of the exciter, filter a direct current component and a phase frequency multiplication component in the field current to obtain a current simultaneously containing odd-numbered harmonics and even-numbered harmonics, divide the current simultaneously containing the odd-numbered harmonics and even-numbered harmonics into two paths to obtain a first current and a second current, delay the second current by a reference time to obtain a first delayed field current, subtract the first current and the first delayed field current to obtain a current containing the odd-numbered harmonics, and detecting the one-phase open circuit of the rotating diode according to the current containing odd harmonics and even harmonics and the current containing odd harmonics.
According to the method and the system for detecting the one-phase open circuit of the rotating diode of the multiphase angular contact brushless exciter, the obtained exciting current entering the stator exciting winding of the exciter is processed to obtain the current simultaneously containing odd harmonics and even harmonics and the current containing the odd harmonics. The current containing odd harmonics and even harmonics and the current containing odd harmonics are analyzed, the current containing even harmonics is extracted to be used as a fault judgment basis, and the fault detection of the one-phase open circuit of the rotating diode of the multiphase angular connection brushless exciter can be carried out.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. A method for detecting one-phase open circuit of a rotating diode of a multi-phase angle-connection brushless exciter is characterized by comprising the following steps:
obtaining the exciting current entering a stator exciting winding of an exciter;
filtering out direct current components and phase frequency multiplication components in the exciting current to obtain current containing odd harmonics and even harmonics;
dividing the current containing odd harmonics and even harmonics into two paths to obtain a first current and a second current, and delaying the second current by reference time to obtain a first delayed exciting current;
subtracting the first current from the first delayed excitation current to obtain a current containing odd harmonics;
detecting a rotating diode one-phase open circuit according to the current simultaneously containing odd harmonics and even harmonics and the current containing the odd harmonics;
the step of detecting the one-phase open circuit of the rotating diode according to the current containing odd harmonics and even harmonics and the current containing odd harmonics comprises the following steps:
obtaining a current steady-state effective value simultaneously containing odd harmonics and even harmonics according to the current simultaneously containing odd harmonics and even harmonics;
obtaining a current steady-state effective value containing odd harmonics according to the current containing odd harmonics;
and carrying out one-phase open circuit detection on the rotating diode according to the current steady-state effective value simultaneously containing odd harmonics and even harmonics and the current steady-state effective value containing odd harmonics.
2. The method according to claim 1, wherein the step of filtering out a direct-current component and a phase frequency multiplication component in the exciting current to obtain a current containing odd-order and even-order harmonics simultaneously comprises the following steps:
dividing the exciting current into two paths to obtain a first exciting current and a second exciting current;
delaying the second exciting current for a reference time to obtain a second delayed exciting current;
subtracting the first exciting current from the second delayed exciting current, filtering out a direct-current component and a phase number frequency multiplication component in the exciting current, and obtaining a current simultaneously containing odd-order and even-order harmonics, wherein the reference time is the quotient of the reference time and the phase number of the exciter.
3. The method of claim 1, wherein the reference time is the inverse of twice the exciter field current frequency.
4. The method of claim 1, wherein the step of obtaining the steady state effective value of the current containing both odd and even harmonics according to the current containing both odd and even harmonics comprises the steps of:
obtaining the mean value of the square sum of the currents containing odd harmonics and even harmonics in a current period;
and acquiring the arithmetic square root of the mean value of the square sum to obtain the current steady-state effective value containing odd harmonics and even harmonics simultaneously.
5. The method of claim 1, wherein said step of deriving a steady state effective value of a current containing odd harmonics from said current containing odd harmonics comprises the steps of:
acquiring the mean value of the square sum of the currents containing odd harmonics in a current period;
and acquiring the arithmetic square root of the mean value of the square sum to obtain the current steady-state effective value containing odd harmonics.
6. The method according to claim 1, wherein said step of rotating diode one-phase open circuit detection based on said steady state effective values of currents containing both odd and even harmonics and said steady state effective values of currents containing odd harmonics comprises the steps of:
acquiring the ratio of the current steady-state effective value containing odd harmonics and even harmonics and the current steady-state effective value containing odd harmonics;
and when the ratio is above a preset threshold value, judging that the rotating diode of the exciter has a one-phase open-circuit fault.
7. The method of claim 6, wherein the preset threshold is 1000.
8. The method of claim 1, wherein said step of subtracting said first current and said first delayed excitation current to obtain a current having odd harmonics comprises the steps of:
and subtracting the first current and the first delayed excitation current by an inverted addition circuit or a differential circuit to obtain a current containing odd harmonics.
9. A polyphase angular joint brushless exciter rotating diode one-phase open circuit detection system is characterized by comprising an acquisition device and a processing device, wherein the acquisition device is connected with the processing device and is connected with a stator excitation winding of an exciter;
the collecting device is used for obtaining exciting current entering a stator exciting winding of an exciter, the processing device is used for obtaining exciting current entering the stator exciting winding of the exciter, filtering direct current components and phase number frequency multiplication components in the exciting current to obtain current simultaneously containing odd harmonics and even harmonics, dividing the current simultaneously containing the odd harmonics and the even harmonics into two paths to obtain first current and second current, delaying the second current for reference time to obtain first delayed exciting current, subtracting the first current from the first delayed exciting current to obtain current containing odd harmonics, and obtaining current steady-state effective values simultaneously containing the odd harmonics and the even harmonics according to the current simultaneously containing the odd harmonics and the even harmonics; obtaining a current steady-state effective value containing odd harmonics according to the current containing odd harmonics; and carrying out one-phase open circuit detection on the rotating diode according to the current steady-state effective value simultaneously containing odd harmonics and even harmonics and the current steady-state effective value containing odd harmonics.
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| CN112986816B (en) * | 2019-12-12 | 2022-03-29 | 南京南瑞继保电气有限公司 | Brushless exciter armature side fault online detection device and method |
| CN111308346B (en) * | 2020-04-08 | 2021-05-11 | 清华大学 | Method and system for detecting a fault in a field winding of a stator of a polyphase brushless exciter |
| CN111308345B (en) * | 2020-04-08 | 2021-10-22 | 清华大学 | Method and system for detecting electrical fault of brushless exciter and storage medium |
| CN111650510B (en) * | 2020-05-12 | 2022-10-18 | 浙江浙能电力股份有限公司台州发电厂 | Fault judgment method and device for brushless excitation motor, computer equipment and medium |
| CN112098838B (en) * | 2020-08-25 | 2023-05-02 | 阳江核电有限公司 | Method and device for detecting faults of diode open circuit of multiphase angular brushless excitation system |
| CN111983452B (en) * | 2020-08-31 | 2023-05-05 | 清华大学 | Method and system for detecting armature winding faults in a multiphase brushless exciter |
| CN111983419B (en) * | 2020-08-31 | 2023-06-23 | 清华大学 | Method and system for detecting diode faults in a multiphase brushless exciter rectifier |
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