• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    System and method of protection against defects between turns in the excitation winding of outgoing pole synchronous machines based on the Fourier analysis of the dispersed flow signal, where from the ratio of the harmonic amplitudes corresponding to the electrical frequency of the machine (f1) and at the turning frequency (f1/p), it is determined if there is a defect. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2738649A1
    申请号:ES201930913
    申请日:2019-10-15
    公开日:2020-01-24
    发明作者:Gaona Carlos Antonio Platero；Pengfei Tian；Cid Jose Maria Martinez
    申请人:Universidad Politecnica de Madrid；
    IPC主号:
    专利说明:

    [0001]
    [0002] SYSTEM AND METHOD OF PROTECTION BEFORE FAULTS BETWEEN SPIRES IN
    [0003]
    [0004] OBJECT OF THE INVENTION
    [0005]
    [0006] The present invention consists of a new protection by detecting faults between turns in the excitation windings of synchronous outgoing pole machines when the machine is in operation.
    [0007]
    [0008] A clear application is the electric power generation systems, in which synchronous generators are used. With the system object of the present invention it is intended to detect the defect between turns in the excitation windings in outgoing pole machines through the measurement of the dispersed flow outside the machine.
    [0009]
    [0010] BACKGROUND OF THE INVENTION
    [0011]
    [0012] Every electrical installation must be equipped with protection systems that make it safe against possible short circuits and other defects that may cause damage to the facilities themselves as well as to people.
    [0013]
    [0014] In the case of generation groups, these protections must also guarantee the supply of energy to the network as reliably as possible, trying to discriminate the severity levels of the failures that occur.
    [0015]
    [0016] One of the possible defects that can occur in synchronous machines is the lack between turns in the excitation windings.
    [0017]
    [0018] The excitation windings are fed by direct current. The defect between turns in these windings may not be dangerous, admitting in some machines a certain percentage of turns in short circuit.
    [0019]
    [0020] However, defects between turns can become a serious problem. for synchronous machines, since they can lead to high excess current, pendulum oscillations, thermal problems and short circuits in the excitation winding.
    [0021]
    [0022] Therefore, it is a usual practice to check the state of the excitation winding when the machine is completely stopped.
    [0023]
    [0024] One of the most used methods is known as pole balance (Pole drop test). This test consists of feeding the excitation winding with a certain voltage and checking the voltage at each of the poles that make up the winding. If any of the measured voltages is lower than the rest of the poles, this indicates that there is a defect between turns on the corresponding pole. Normally this test is performed with an AC voltage source, although it also works with direct current.
    [0025]
    [0026] Another method is the application of a voltage wave with many frequencies, and an analysis of the frequency response of the winding. It can be done with a square wave (Dirac delta type) or with a sine wave where the frequency is varied. To assess whether the winding is defective or does not compare the test result with another test under normal conditions without defect. Another possibility is to perform the pole-to-pole test and compare them, if any pole has a different frequency response, it indicates that it has a defect.
    [0027]
    [0028] All these methods need the machine to be out of order to verify if there is a defect between turns in the excitation winding.
    [0029]
    [0030] In addition, a series of patents and articles related to the invention should be taken into account:
    [0031]
    [0032] PCT / US2010 / 021948 (25.01.2010) ES2426970 T3 (28.10.2013) General Electric Company (100.0%) ROBUST ON-LINE STATOR TURN FAULT IDENTIFICATION SYSTEM. This patent does not detect defects between turns in the rotor.
    [0033]
    [0034] P201431921 (23.12.2014) ES2534950 A1 (04.30.2015) UNIVERSIDAD POLITÉCNICA DE MADRID (100.0%) System and method of protection against failures between turns in synchronous machines. This patent is based on the calculation of the theoretical excitation current, and can only be used with machines of which previous trials are available.
    [0035]
    [0036] M. Cuevas, R. Romary, J. Lecointe, F. Morganti and T. Jacq, "Noninvasive Detection of Winding Short-Circuit Faults in Salient Pole Synchronous Machine With Squirrel-Cage Damper," in IEEE Transactions on Industry Applications, vol.
    [0037] 54, no. 6, pp. 5988-5997, Nov.-Dec. 2018. In this document to detect the lack between turns, the corresponding dispersed flow is measured with the rotation frequency, from which it is very difficult to determine if there is a defect because this component of the corresponding dispersed flow with the rotation frequency depends a lot of the machine's operating point.
    [0038]
    [0039] DESCRIPTION OF THE INVENTION
    [0040]
    [0041] The present invention relates to a protection system and method designed to detect defects between turns of the excitation winding of synchronous outgoing pole machines with the machine in operation. The machine has p pairs of poles.
    [0042]
    [0043] When the generator is running or even in a vacuum with voltage in the armature winding, a dispersion flow appears outside the machine. This dispersion flow has a variable amplitude, which depends on several factors such as voltage, active power, reactive power and therefore the excitation current. It also depends on the point where it is measured.
    [0044]
    [0045] In the case of normal operation, that is to say without defects in the windings, the fundamental frequency of this dispersed flow corresponds to the electrical frequency (f1) of the machine (Normally 50 Hz or 60 Hz) although there are other harmonics of smaller amplitude.
    [0046]
    [0047] However, in case of defects between turns in the excitation winding, a component appears in the flow related to the machine's rotation frequency (f1 / p).
    [0048]
    [0049] The main problem of analyzing this component of the corresponding dispersed flow with the machine's rotation frequency (f1 / p) is precisely that it depends on a multitude of factors such as; the voltage, the active power, the reactive power and the excitation current, in addition to the number of short circuits in the rotor. Therefore, it is very difficult to assess whether the machine has or not defects in the rotor.
    [0050]
    [0051] In this sense, as commented, the team of researchers (M. Cuevas, R. Romary, J. Lecointe, F. Morganti and T. Jacq) have conducted tests, and determine that there is a defect if the corresponding frequency component With the turning speed, it exceeds a certain threshold. However, as stated, its value depends on the operating point, so the value of this component is very variable and it is very difficult to determine whether or not there is a short circuit in the excitation windings.
    [0052]
    [0053] After many laboratory tests with a synchronous outgoing pole machine, where defects can be made in the rotor, we have confirmed that the dispersed flow depends on the machine's operating point. In the case of machine operation absorbing reactive energy (underexcited), the value of the dispersed flow is much smaller than in the case of operation generating reactive energy (overexcited).
    [0054]
    [0055] In the case of having faults between turns in the rotor a dispersed flow component corresponding to the machine's rotation frequency appears, that is to say as many times as slow as the number of pairs of poles the machine has. This component of the dispersed flow also varies markedly with the point of operation of the machine and with the percentage of turns in short circuit. Therefore, making a diagnosis of the machine based on the amplitude of this component of the dispersed flow is very difficult, as already explained.
    [0056]
    [0057] It has been found that, if a relationship is made between the components of the dispersed flow of frequency of rotation and electrical frequency, this relationship remains practically constant regardless of the point of operation of the machine, and this relationship depends almost exclusively on the severity of the fault, that is to say the number of turns that are in short circuit.
    [0058]
    [0059] Therefore, the diagnosis of the machine can be carried out in a much more reliable way, regardless of the point of operation for which the invention is based on relating the two components of the flow, instead of relying solely on the amplitude of the corresponding component. at the frequency of rotation. For this, as in the state of the art, the invention employs a device for measuring the dispersed flow outside the machine that makes the measurement of said dispersed flow, and uses a Fourier transform calculating equipment, configured to obtain the different harmonics; among them those corresponding to the electric frequency and the frequency of rotation. Subsequently, using a mathematical calculator, a signal is generated from the different harmonics of dispersed flow. Finally, use a comparator of the mathematical calculator output with a threshold to determine if there is a defect. The novelty of the system of the invention consists in incorporating a new structure of the calculating equipment and of the comparator, which have been configured to determine if there is a defect between turns in the excitation winding by means of the ratio of the values of the amplitudes of the harmonics corresponding to the frequency of rotation and the electrical frequency of the machine.
    [0060]
    [0061] In the preferred embodiment of the invention, the calculator is configured to determine if there is a defect by subtracting the amplitudes of the harmonics corresponding to the rotation frequency and the electrical frequency of the machine, which is compared with a previously established threshold.
    [0062]
    [0063] One of the possible relationships between both components of the dispersed flow provided by the invention is to pass them to decibels and subtract them, although others may exist, to determine if there is a defect.
    [0064]
    [0065] In addition, it is envisioned that the invention comprises a timer to prevent unwanted triggering.
    [0066]
    [0067] The method of the invention comprises the phases that allow performing the different operational steps that were described above of the operation of the system.
    [0068]
    [0069] The configuration and method described are capable of operating with the machine running and analyzing a single physical variable, the dispersed flow. What constitutes a great advantage over the state of the art.
    [0070]
    [0071] In addition, the invention solves the problem of detecting internal faults without the need to disassemble any part of the machine.
    [0072]
    [0073] Another advantage of the invention is that the proposed method is independent of the machine's operating point.
    [0074] BRIEF DESCRIPTION OF THE FIGURES
    [0075]
    [0076] Next, two figures that help to better understand the invention and that expressly relate to an embodiment of said invention which is presented as a non-limiting example thereof are described very briefly.
    [0077]
    [0078] Figure 1 shows the elements of the fault protection system between turns for an excitation winding, based on the analysis of the components of the dispersed flow by means of a mathematical function. These are:
    [0079]
    [0080] 1. Outgoing pole synchronous machine with p pairs of poles.
    [0081]
    [0082] 2. Induced winding of the synchronous machine
    [0083]
    [0084] 3. Excitation winding of the synchronous machine
    [0085]
    [0086] 4. Flow sensor
    [0087]
    [0088] 5. Dispersed flow signal
    [0089]
    [0090] 6. Scattered flow measurement equipment
    [0091]
    [0092] 7. Fourier transform calculator equipment
    [0093]
    [0094] 8. Harmonic of flow corresponding to the electric frequency f1.
    [0095]
    [0096] 9. Flow harmonic corresponding to the frequency of rotation f1 / p.
    [0097]
    [0098] 10. Mathematical calculator
    [0099]
    [0100] 11. Mathematical calculator output signal
    [0101]
    [0102] 12. Threshold to determine that there is a defect
    [0103]
    [0104] 13. Comparator
    [0105]
    [0106] 14. Adjustable timer
    [0107]
    [0108] 15. Trigger signal
    [0109]
    [0110] Figure 2 shows the elements of the fault protection system between turns for excitation winding based on the analysis of the components of the dispersed flow by subtracting the two components expressed in decibels.
    [0111] The elements are identical, except that the mathematical calculator corresponds to the subtraction of the two components expressed in decibels.
    [0112]
    [0113] PREFERRED EMBODIMENT
    [0114]
    [0115] The following is a description of one of the possible embodiments of this invention for illustrative and non-limiting purposes.
    [0116]
    [0117] This preferred embodiment is based on the subtraction of the flow signals of the dispersed flow components of electric frequency (f1) and rotation frequency (f1 / p) expressed in decibels [dB]. This preferred embodiment corresponds to Figure 2.
    [0118]
    [0119] For this preferred embodiment, a flow sensor (4) must be installed on the outside of the outgoing pole synchronous machine (1). The signal from this sensor (5) will be connected to a dispersed flow measurement device (6).
    [0120]
    [0121] In addition, it comprises a Fourier transform calculator equipment (7), which performs an analysis of the measured signal of dispersed flow, decomposing said signal into different components. Of which the corresponding to the electric frequency (8) and the corresponding to the turning frequency (9) will be used. These two signals will go to a mathematical calculator (10).
    [0122]
    [0123] The harmonics corresponding to the electric frequency (8) and the turning frequency (9) will be converted into decibels, inside the calculator (10) obtaining two measures:
    [0124]
    [0125] • Machine electrical frequency measurement A f1 [dB]
    [0126]
    [0127] • Measurement at machine rotation frequency A f1 / p [dB].
    [0128]
    [0129] Subsequently, the difference of both measurements is made, obtaining A [dB] also expressed in decibels, which is the output (11) of the calculator, according to the following expression.
    [0130]
    [0131] A = A f 1 - f í f1 / p [dfí]
    [0132]
    [0133] The output signal (11) of the calculator (10) is A, and remains practically constant regardless of the point of operation, and only depends on the severity of the defect, that is to say the percentage of windings of the rotor winding that is short-circuited.
    [0134]
    [0135] The signal (11) is compared with a threshold (12), previously established, in a comparator (13). This threshold depends on the percentage of turns that are allowed to be short-circuited, which is established by the machine manufacturer. The comparator output goes to an adjustable timer (14) to generate the trigger signal (15), so that the timing prevents an unwanted trip.
    [0136] The elements of Figure 1 are identical to those described for Figure 2, with the difference that the mathematical calculator (10) instead of expressing the two components (8 and 9) in decibels and then subtracting them, expresses them in any other variable and relates them to determine if there is a defect, equivalent to the description made.
    权利要求:
    Claims (8)
    [1]
    1. System for protection against faults between turns in excitation windings of outgoing pole synchronous machines based on the measurement of the dispersion flow outside the machine, comprising:
    - a measuring device (6) of the dispersed flow outside the machine;
    - a Fourier transform calculator device (7) for the mediated dispersed flow signals, configured to obtain the different harmonics;
    - a mathematical calculator (10), for generating a signal from the different harmonics of dispersed flow;
    - a comparator (13), of the output of the mathematical calculator (10) with a threshold (12) to determine if there is a defect.
    characterized in that said calculating equipment and the comparator are configured to determine if there is a defect between turns in the excitation winding by means of the ratio of the values of the amplitudes of the harmonics corresponding to the rotation frequency and the electrical frequency of the machine.
    [2]
    2. Fault protection system between turns in excitation windings of outgoing pole synchronous machines based on claim 1, characterized in that the calculator is configured to determine if there is a defect by subtracting the amplitudes of the harmonics corresponding to the frequency of rotation and to the electrical frequency of the machine, which is compared with a previously established threshold.
    [3]
    3. Fault protection system between turns in excitation windings of outgoing pole synchronous machines based on claim 2, characterized in that the calculator is configured to determine if there is a defect by subtracting the amplitudes of the harmonics corresponding to the frequency of rotation and the electrical frequency of the machine, expressed in decibels.
    [4]
    4. Failure protection system between turns in excitation windings of outgoing pole synchronous machines based on claims 1 and 2, characterized in that it comprises an adjustable timer (14).
    [5]
    5. Method of protection against faults between turns in excitation windings of synchronous outgoing pole machines, comprising:
    - a stage of measurement of the dispersed flow outside the machine;
    - a step of calculating the Fourier transform of the dispersed flow signals in which the different harmonics of the measured dispersed flow signal are obtained;
    - a stage of mathematical calculation, which generates a signal from the different harmonics of dispersed flow;
    - a comparator stage of the output of the mathematical calculation stage, with a threshold previously established to determine if there is a defect.
    characterized in that it comprises determining whether there is a defect between turns in the excitation winding by means of the ratio of the values of the amplitudes of the harmonics corresponding to the turning frequency and the electrical frequency of the machine.
    [6]
    6. Method of protection against faults between turns in excitation windings of outgoing pole synchronous machines based on claim 5, characterized in that it determines whether there is a defect by subtracting the amplitudes of the harmonics corresponding to the frequency of rotation and frequency electric machine.
    [7]
    7. Failure protection method between turns in excitation windings of outgoing pole synchronous machines based on claim 6, characterized in that it determines whether there is a defect by subtracting the amplitudes of the harmonics corresponding to the frequency of rotation and frequency electric machine expressed in decibels.
    [8]
    8. Failure protection system between turns in excitation windings of outgoing pole synchronous machines based on claims 4 and 5, characterized in that it comprises an adjustable timing stage.
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    引用文献:
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    CN106772037A|2016-12-15|2017-05-31|华北电力大学（保定）|Synchronous generator rotor winding interturn short-circuit diagnostic method based on twin coil|
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    ES201930913A|ES2738649B2|2019-10-15|2019-10-15|SYSTEM AND METHOD OF PROTECTION AGAINST FAULTS BETWEEN SPIRES IN EXCITATION WINDINGS OF SYNCHRONOUS POLES OF PROJECTING POLES|ES201930913A| ES2738649B2|2019-10-15|2019-10-15|SYSTEM AND METHOD OF PROTECTION AGAINST FAULTS BETWEEN SPIRES IN EXCITATION WINDINGS OF SYNCHRONOUS POLES OF PROJECTING POLES|
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