Dry-type air-core reactor inter-turn short circuit fault detection method based on resonant peak average offset

Abstract

The application discloses a kind of based on resonant wave crest average displacement amount's dry-type air-core reactor interturn short-circuit fault detection method, comprising: constructing the circuit model simulation normal operation of dry-type air-core reactor and the interturn short-circuit of different fault degree and fault location, and the corresponding impedance logarithmic amplitude spectrum is obtained;Respectively calculate the resonant wave crest displacement amount and eigenvalue of the impedance logarithmic amplitude spectrum corresponding to each interturn short-circuit;The impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be measured is obtained and the resonant wave crest displacement amount and eigenvalue are calculated;If resonant wave crest displacement amount is greater than preset threshold value, resonant wave crest displacement amount and eigenvalue are matched with the resonant wave crest displacement amount and eigenvalue of the impedance logarithmic amplitude spectrum corresponding to each interturn short-circuit, and the matching result is used to determine the interturn short-circuit fault position and fault degree of the dry-type air-core reactor to be measured.The application improves the accuracy of dry-type reactor interturn short-circuit fault detection, and guarantees the safe operation of dry-type air-core reactor.

Description

Technical Field

[0001] The present invention relates to the technical field of dry-type air-core reactors, and in particular to a method for detecting inter-turn short-circuit faults of dry-type air-core reactors based on an average offset of a resonance wave peak. Background Art

[0002] With the continuous advancement of domestic power infrastructure and the continued expansion of ultra-high voltage and ultra-high voltage power grids, high-quality, high-tech transmission equipment, including reactors, has become an indispensable component supporting power grid development. At the same time, as the level of my country's ultra-high voltage power grid continues to improve, the requirements for the safe and stable operation of reactors are becoming increasingly stringent. With the large-scale commissioning and long-term operation of dry-type air-core reactors, their failure rate has continued to rise, 70% of which are caused by inter-turn short-circuit faults. However, existing monitoring methods cannot detect inter-turn short-circuit faults in a timely manner, which can easily lead to reactor burnout and cause more serious ground short-circuit faults, threatening the safe and stable operation of the power system.

[0003] Currently, the main online detection technologies for inter-turn short-circuit faults in reactors include temperature field detection, magnetic field detection, and electrical parameter detection. For example, fiber optic temperature sensing and infrared temperature measurement technologies are convenient. However, existing technologies only work for monitoring points within a specific range and cannot sensitively detect temperature changes at monitoring points outside the measurement range. Magnetic field detection is limited by the accuracy of the installed external sensor, and the magnetic field generated during a fault weakens the original magnetic field, resulting in a certain degree of error. Regarding electrical parameter detection, in the early stages of a fault, the changes in the reactor's electrical parameters, such as inductance and resistance, are very small, making the reliability of fault information reflected by these electrical parameter changes poor. While it is technically feasible to perform inter-turn insulation testing on dry-type air-core shunt reactors using high-frequency pulse oscillation, this method requires the reactor to be powered off, resulting in poor timeliness in winding insulation fault diagnosis. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the fault detection characteristic quantities in the existing dry-type air-core reactor protection scheme are only applicable at low frequencies, but when the frequency increases to high frequencies, some characteristic quantities will be unable to detect and eliminate the dry-type air-core reactor inter-turn short-circuit fault, causing the fault to evolve into a ground short-circuit fault or a more serious fire accident, affecting the safe and stable operation of the power system.

[0005] In response to the above-mentioned problems of the existing technology, a method for detecting inter-turn short-circuit faults of dry-type air-core reactors based on the average offset of the resonant wave peak is proposed, which improves the accuracy of inter-turn short-circuit fault detection of dry-type reactors, avoids further expansion of accidents, ensures the safe operation of dry-type air-core reactors, and ensures the sensitivity and reliability of inter-turn short-circuit fault detection.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for detecting inter-turn short-circuit faults in dry-type air-core reactors based on the average offset of resonance peaks:

[0008] Constructing a circuit model of a dry-type air-core reactor, using the circuit model to simulate normal operation of the dry-type air-core reactor and inter-turn short circuits with different fault degrees and fault locations, and obtaining corresponding impedance logarithmic amplitude spectra;

[0009] Calculate the resonance peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit of the dry-type air-core reactor respectively, wherein the resonance peak offset specifically refers to the offset of the resonance peak of the impedance logarithmic amplitude spectrum compared to the resonance peak of the impedance logarithmic amplitude spectrum when the dry-type air-core reactor is operating normally;

[0010] Obtaining an impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested, and calculating a resonant peak offset and a characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested;

[0011] If the resonant peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested is greater than a preset threshold, the resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested are matched with the resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit, and the inter-turn short circuit fault location and fault degree of the dry-type air-core reactor to be tested are determined according to the matching results.

[0012] Furthermore, constructing a circuit model of a dry-type air-core reactor specifically includes the following steps:

[0013] Establish a distributed equivalent circuit model of the reactor at high frequencies, calculate the inter-turn capacitance, inter-layer capacitance, stray capacitance to ground, coil self-inductance, and mutual inductance;

[0014] Write the Kirchhoff current law equation for any node i in the distributed equivalent circuit model of the reactor, then write the voltage and current equations of the inductor and resistor branches adjacent to the node i, and organize them into the form of an admittance matrix. After the node voltage and current are obtained, the inverse of the admittance matrix is ​​calculated to obtain the impedance value.

[0015] Furthermore, the expression of the admittance matrix form is as follows:

[0016] [Y]·[ΔU+U']=[I]

[0017] Where [Y] is the admittance matrix of the equivalent circuit model, ΔU represents the node voltage difference, and U' represents the mutual inductance voltage drop.

[0018] Furthermore, when respectively calculating the resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit of the dry-type air-core reactor, the step of calculating the resonant peak offset of the impedance logarithmic amplitude spectrum includes:

[0019] Obtain the frequency f corresponding to the maximum value of the resonance peak in the impedance logarithmic amplitude spectrum of the dry-type air-core reactor during normal operation M The frequencies f1, f2...f corresponding to other resonance peaks n ;

[0020] Get the frequency f corresponding to the maximum value of the resonant peak in the impedance logarithmic amplitude spectrum corresponding to the current inter-turn short circuit M 'Frequencies f1', f2'...f corresponding to other resonance peaks n ';

[0021] Calculate the frequency f corresponding to the maximum value of the resonant peak in the impedance logarithmic amplitude spectrum corresponding to the current inter-turn short circuit M 'Relative to frequency f M The offset Δf M , and calculate the frequencies f1', f2'...f corresponding to other resonant peaks in the impedance logarithmic amplitude spectrum corresponding to the current inter-turn short circuit n 'Relative to frequencies f1, f2...f n The offset Δf1, Δf2...Δf n , calculate the offset Δf M , Δf1, Δf2...Δf n The average value of Δf is obtained to obtain the resonance peak offset Δf corresponding to the current inter-turn short circuit.

[0022] Furthermore, when respectively calculating the resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit of the dry-type air-core reactor, the step of calculating the characteristic value of the impedance logarithmic amplitude spectrum includes:

[0023] The absolute value of the impedance logarithmic amplitude spectrum waveform corresponding to the current inter-turn short circuit is integrated to obtain the corresponding characteristic waveform, and the change trend of the specified position of the characteristic waveform is calculated to obtain the characteristic value corresponding to the current inter-turn short circuit.

[0024] Furthermore, the calculation of the change trend of the specified position of the characteristic waveform includes:

[0025] Obtaining an inflection point value A1 of the first stage in the characteristic waveform, and step stability values ​​A2 and A3 of the second and third stages in the characteristic waveform;

[0026] Calculate the ratio of the stable value A2 at the step in the second stage to the inflection point value A1 in the first stage as the first eigenvalue K1 corresponding to the current inter-turn short circuit, and calculate the ratio of the stable value A3 at the step in the third stage to the stable value A2 at the step in the second stage as the second eigenvalue K2 corresponding to the current inter-turn short circuit.

[0027] Furthermore, after respectively calculating the resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit of the dry-type air-core reactor, the method includes: dividing the resonant peak offset intervals of the impedance logarithmic amplitude spectrum corresponding to inter-turn short circuits of different fault degrees according to the value of the resonant peak offset, and constructing a set of resonant peak offsets of the impedance logarithmic amplitude spectrum corresponding to inter-turn short circuits of different fault locations under the same fault degree;

[0028] The characteristic values ​​of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit with different fault degrees are fitted to obtain the characteristic value change trend of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit with different fault degrees.

[0029] Furthermore, when matching the resonance peak offset and characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested with the resonance peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit, the method includes:

[0030] Match the resonance peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested with the resonance peak offset interval of the impedance logarithmic amplitude spectrum corresponding to different fault degrees of inter-turn short circuit, and determine the corresponding inter-turn short circuit fault degree according to the matching result;

[0031] Comparing the characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested with the characteristic value change trend of the impedance logarithmic amplitude spectrum corresponding to the determined inter-turn short-circuit fault degree, if the characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested matches the characteristic value change trend of the impedance logarithmic amplitude spectrum corresponding to the determined inter-turn short-circuit fault degree, then the inter-turn short-circuit fault degree of the dry-type air-core reactor to be tested is the determined inter-turn short-circuit fault degree;

[0032] The resonance peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested is matched with the set of resonance peak offsets of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit at different fault locations in the determined inter-turn short circuit fault degree, and the corresponding inter-turn short circuit fault location is determined according to the matching result.

[0033] Furthermore, when obtaining the impedance logarithmic amplitude spectrum of the dry-type air-core inductor to be tested, it includes: real-time collection of the frequency parameter measurement value of the resonant point in the impedance logarithmic amplitude spectrum and preprocessing, and then comparing it with the corresponding frequency parameter simulation value in the circuit model to determine whether the frequency parameter measurement value belongs to an abnormal point. If so, the corresponding data is discarded; otherwise, the corresponding data is retained.

[0034] The present invention also proposes a dry-type air-core reactor inter-turn short-circuit fault detection system based on the average offset of the resonance peak, comprising a microprocessor and a computer-readable storage medium connected to each other, wherein the microprocessor is programmed or configured to execute any one of the dry-type air-core reactor inter-turn short-circuit fault detection methods based on the average offset of the resonance peak.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] The present invention selects the average offset of the resonant peak in the impedance amplitude spectrum to determine the degree of the inter-turn short-circuit fault of the dry-type air-core reactor, and defines a characteristic value for auxiliary judgment, thereby analyzing the high-frequency characteristics of the reactor and ensuring the sensitivity and reliability of inter-turn short-circuit fault detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The following is a brief flow chart of a method according to an embodiment of the present invention.

[0038] Figure 2 Detailed flowchart of the method according to an embodiment of the present invention.

[0039] Figure 3 This is a simulation model established in an embodiment of the present invention.

[0040] Figure 4 It is the logarithmic amplitude spectrum of the reactor impedance under normal operating conditions.

[0041] Figure 5 It is the logarithmic amplitude spectrum of the inter-turn short-circuit impedance of different degrees at the head end.

[0042] Figure 6 It is the logarithmic amplitude spectrum of the inter-turn short-circuit impedance at different degrees at the middle end.

[0043] Figure 7 It is the logarithmic amplitude spectrum of the inter-turn short-circuit impedance at different degrees at the end.

[0044] Figure 8 Impedance logarithmic magnitude spectrum for 10% inductance reduction at different locations.

[0045] Figure 9 Schematic diagram of features A1, A2, and A3 in the characteristic waveform of the impedance logarithmic amplitude spectrum.

[0046] Figure 10 The characteristic waveform of the impedance logarithmic amplitude spectrum of different degrees of inter-turn short circuit at the head end.

[0047] Figure 11 The waveform characteristic value changes with the severity of the inter-turn short circuit. DETAILED DESCRIPTION

[0048] The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby.

[0049] Example 1

[0050] To address the problems existing in existing reactor inter-turn short-circuit detection technologies, this embodiment proposes a method for detecting inter-turn short-circuit faults in dry-type air-core reactors based on the average offset of the resonant peak. Based on the multi-conductor transmission line theory, a high-frequency distributed parameter equivalent model of the reactor is established, and a Simulink circuit model is constructed. Simulations are performed on the reactor when inter-turn short-circuit faults of varying degrees occur at high frequencies. Based on the simulation results, the resonant peak offsets and eigenvalues ​​of the impedance logarithmic amplitude spectrum of inter-turn short-circuits of varying fault degrees and fault locations are statistically analyzed. Subsequently, the resonant peak offsets and eigenvalues ​​of the impedance logarithmic amplitude spectrum of the measured data of the dry-type air-core reactor are matched with the statistical results to determine whether the dry-type air-core reactor has experienced inter-turn short-circuit faults of varying degrees.

[0051] like Figure 1 As shown, the method of this embodiment includes the following steps:

[0052] S1) constructing a circuit model of a dry-type air-core reactor;

[0053] S2) using the circuit model to simulate the normal operation of the dry-type air-core reactor and inter-turn short circuits with different fault degrees and fault locations, and obtaining corresponding impedance logarithmic amplitude spectra, and respectively calculating the resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit of the dry-type air-core reactor. In this embodiment, the resonant peak offset specifically refers to the offset of the resonant peak of the impedance logarithmic amplitude spectrum compared to the resonant peak of the impedance logarithmic amplitude spectrum when the dry-type air-core reactor is operating normally, and the characteristic value specifically refers to the change trend of a specified position in a characteristic waveform obtained by integrating the impedance logarithmic amplitude spectrum;

[0054] S3) obtaining an impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested, and calculating a resonance peak offset and a characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested;

[0055] S4) If the resonant peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested is less than a preset threshold, it indicates that no inter-turn short circuit fault has occurred;

[0056] If the resonant peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested is greater than a preset threshold, it indicates that an inter-turn short circuit fault has occurred. The resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested are matched with the resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit. The inter-turn short circuit fault location and fault severity of the dry-type air-core reactor to be tested are determined based on the matching results.

[0057] The following combination Figure 2 Each step is described in detail.

[0058] Step S1 of this embodiment establishes a high-frequency distributed parameter equivalent model of the reactor based on the multi-conductor transmission line theory and builds a Simulink circuit model to simulate the occurrence of inter-turn short-circuit faults of varying degrees in the reactor at high frequencies. Specifically, the following steps are included:

[0059] First, based on multi-conductor transmission line theory, a distributed equivalent circuit model of the reactor at high frequencies was established. To simplify the analysis, the dry-type air-core reactor was set to have x coil layers, with each coil layer divided into y parts along the height direction. The inter-turn capacitance, inter-layer capacitance, and stray capacitance to ground were theoretically derived. The coil's self-inductance and mutual inductance were calculated using the inductance calculation model for coaxial thin-walled solenoids.

[0060] Then, write the Kirchhoff current law equation for any node i in the reactor distribution equivalent circuit model, and write the voltage and current equations of the inductor and resistor branches adjacent to the node i. After being organized into the form of an admittance matrix, it is shown as follows:

[0061] [Y]·[ΔU+U']=[I]

[0062] Where ΔU represents the node voltage difference, U' represents the mutual inductance voltage drop, and [Y] is the admittance matrix of (R+jωL). Its inductance value is related to the change of frequency. As the frequency increases, the change of mutual inductance coefficient is much greater than that of self-inductance. When a turn-to-turn short circuit fault occurs, the inductance value drops significantly, and the impedance value then changes significantly.

[0063] Based on the above content, after obtaining the voltage of each node, since the voltage drop of the reactor is distributed according to the capacitance at high frequency, its current will increase numerically due to the decrease in capacitive reactance. After the node voltage and current are calculated, the impedance value can be obtained, that is, the inverse of the admittance matrix. Further taking the logarithm of the impedance value makes the conclusion easy to observe. Plotting the curve of the impedance value changing with frequency under the circuit model of the dry-type air-core reactor obtains the characteristic curve of the impedance logarithmic amplitude spectrum with respect to frequency. This curve can be obtained by simulink simulation calculation. The simulink circuit model of the high-frequency distributed parameter equivalent model of the reactor is as follows Figure 3 shown.

[0064] like Figure 2As shown, step S2 of this embodiment is mainly divided into two stages: pre-processing and real-time processing. The pre-processing stage is to obtain the frequency parameters of the resonance point of the standard impedance logarithmic amplitude spectrum of the dry-type reactor in a set frequency range under normal operating conditions; in the real-time stage, when the reactor is operating, the frequency parameters of the resonance point of the impedance logarithmic amplitude spectrum under different fault degrees when the inductance value decreases by 5%, 10%, 15%, and 20% are obtained in real time, and the average offset of the resonance peak under different fault degrees is calculated, and the fault is judged by comparing it with the set value.

[0065] In step S2 of this embodiment, when respectively calculating the resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit of the dry-type air-core reactor, the step of calculating the resonant peak offset of the impedance logarithmic amplitude spectrum includes:

[0066] S21) Obtain the frequency f corresponding to the maximum value of the resonance peak in the impedance logarithmic amplitude spectrum of the dry-type air-core reactor during normal operation M The frequencies f1, f2...f corresponding to other resonance peaks n ;

[0067] In this embodiment, the impedance logarithmic amplitude spectrum of the normal operating reactor under simulation is obtained as follows: Figure 4 As shown. As the frequency increases, the inductive reactance increases and the capacitive reactance decreases, and the internal circuit of the reactor undergoes series and parallel resonance. In the frequency band where the equivalent circuit resonates, the inductive reactance and the capacitive reactance compete with each other and are very sensitive to parameter changes. Therefore, the frequency band of 100HZ to 100MHZ where the entire circuit resonates should be selected as the starting range of the frequency sweep. The impedance logarithmic amplitude spectrum has a rapid change. Figure 4 The frequency of 21.38 MHZ is the maximum value of the resonance peak. When the frequency of the sweep frequency continues to increase, it shows a downward trend. The frequency of the maximum value of the resonance peak of the normal impedance spectrum is taken as f M , take the frequencies corresponding to other resonance peaks as f1, f2...f n It can be seen that the frequency of the resonance point in the amplitude spectrum is very sensitive to the change of electrical parameters. Therefore, the operating status of the reactor can be analyzed using the impedance logarithmic amplitude spectrum.

[0068] S22) Obtain the frequency f corresponding to the maximum value of the resonance peak in the impedance logarithmic amplitude spectrum corresponding to the current inter-turn short circuit M 'Frequencies f1', f2'...f corresponding to other resonance peaks n ';

[0069] S23) Calculate the frequency f corresponding to the maximum value of the resonance peak in the impedance logarithmic amplitude spectrum corresponding to the current inter-turn short circuit M 'Relative to frequency f M The offset Δf M, and calculate the frequencies f1', f2'...f corresponding to other resonant peaks in the impedance logarithmic amplitude spectrum corresponding to the current inter-turn short circuit n 'Relative to frequencies f1, f2...f n The offset Δf1, Δf2...Δf n , calculate the offset Δf M , Δf1, Δf2...Δf n The average value of Δf is obtained to obtain the resonance peak offset Δf corresponding to the current inter-turn short circuit.

[0070] In this embodiment, when simulating inter-turn short circuits with different fault degrees and fault locations in dry-type air-core reactors, an inter-turn short circuit is first set at the head end to obtain the impedance logarithmic amplitude spectrum when the inductance value decreases by 5%, 10%, 15%, and 20%, as shown in FIG. Figure 5 As shown in the figure, the frequency f corresponding to the new resonance peak when the inductance value of the reactor turns short-circuit fault decreases is measured. M ', f1', f2'...f n ', calculate the offset Δf of the peak maximum value at the resonance point M , and then arbitrarily calculate the peak offset of other resonant point frequencies Δf1, Δf2...Δf n , take the average value of two or more corresponding frequency offsets as the characteristic quantity to measure the inter-turn short circuit fault of the reactor; when the inter-turn short circuit occurs at the first end of the reactor, the peak values ​​of the resonance point will shift to the right. The more serious the fault is, the greater the offset is.

[0071] In this embodiment, considering that when an inter-turn short circuit actually occurs, the amount of inductance drop may not be exactly equal to the drop set during simulation, after calculating the value of the resonant peak offset of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit with different fault degrees, the resonant peak offset intervals of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit with different fault degrees are divided.

[0072] Table 1 below shows the statistical values ​​of the average offset of the resonance point of the inter-turn fault at the head end of the reactor, and further provides the setting values ​​of the resonance peak offset interval corresponding to inter-turn short circuits of different fault degrees. When the average change rate of the offset of the resonance peak is measured to be 0<Δf<2MHZ, it is determined that a slight inter-turn short circuit fault has occurred in the dry-type reactor under test (the inductance value decreases by 0-5%); when the average change rate of the offset of the resonance peak is measured to be 2<Δf<20MHZ, it is determined that a more serious inter-turn short circuit fault has occurred in the dry-type reactor under test (the inductance value decreases by 5%-15%); when the average change rate of the offset of the resonance peak is measured to be Δf>20MHZ, it is determined that a serious inter-turn short circuit fault has occurred in the dry-type reactor under test (the inductance value decreases by more than 15%).

[0073] Table 1 Statistical values ​​of average offset of inter-turn fault resonance point at the first end of the reactor

[0074]

[0075] Similarly, the frequency characteristic curves of the resonance point in the impedance logarithmic amplitude spectrum of different fault degrees can be measured when the fault location is located in the middle of the reactor and the end of the reactor, respectively. Figure 6 and Figure 7 To further explore the relationship between the fault location and the operating state of the reactor, this embodiment also establishes a set of offsets of the resonance peaks of the impedance logarithmic amplitude spectrum for inter-turn short circuits at different fault locations under the same fault severity. That is, the fault locations are plotted as being set at the first layer (the beginning of the reactor), the second layer (the middle of the reactor), and the fourth layer (the end of the reactor) of the reactor, and the offsets of the resonance point peaks in the impedance logarithmic amplitude spectrum at different locations under the same fault severity are obtained, for example Figure 8 To explore the impedance logarithmic amplitude spectrum when the inductance is reduced by 10% at different positions.

[0076] Since actual measurements may be subject to interference factors such as external noise and measurement errors, the average offset of the fault resonance point measured above may vary slightly. For example, when the number of short-circuited turns is small, the slight difference between the resonance peaks in the impedance logarithmic amplitude spectrum may also cause misjudgment due to on-site interference in actual detection, and it is necessary to combine the provided auxiliary criteria. Therefore, this embodiment also constructs a characteristic waveform by integrating the absolute value of the impedance logarithmic amplitude spectrum waveform, thereby improving the identifiability of the inter-turn short circuit. In step S2, when respectively calculating the resonance peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit of the dry-type air-core reactor, the step of calculating the characteristic value of the impedance logarithmic amplitude spectrum is included, specifically including:

[0077] The absolute value of the impedance logarithmic amplitude spectrum waveform corresponding to the current inter-turn short circuit is integrated to obtain the corresponding characteristic waveform, and the change trend of the specified position of the characteristic waveform is calculated to obtain the characteristic value corresponding to the current inter-turn short circuit.

[0078] The characteristic waveform obtained by integrating the absolute value of the impedance logarithmic amplitude spectrum waveform is as follows: Figure 9 As shown in the figure, the first stage shows an upward trend. Since the characteristic waveforms of normal conditions and inter-turn short circuits with different fault degrees at the same fault location are roughly similar (such as Figure 10As shown), if the change in the amplitude of the characteristic waveform is directly used to determine whether a turn-to-turn short-circuit fault has occurred in the dry-type air-core reactor, it may lead to misjudgment. It is necessary to extract characteristic values ​​from it to highlight the difference in detection results under different insulation states. In this embodiment, the characteristic value is obtained by calculating the change trend of the specified position of the characteristic waveform, that is, the two characteristic values ​​K1 and K2 of the characteristic waveform are defined as follows, where A1 is defined as the inflection point value of the first stage, A2 and A3 are respectively the stable values ​​of the characteristic waveform at the steps of the second and third stages. The characteristic values ​​K1 and K2 of the characteristic waveform are calculated, and the expressions are as follows:

[0079] K1=A2 / A1

[0080] K2=A3 / A2

[0081] In this embodiment, after calculating the characteristic values ​​of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit with different fault degrees and different fault locations, the characteristic values ​​of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit with different fault degrees are fitted to analyze their change trends, such as Figure 11 shown.

[0082] Depend on Figure 11 It can be seen that when the reactor has inter-turn short-circuit faults of varying degrees, its characteristic waveforms K1 and K2 will tend to increase first and then decrease, with a peak value appearing when the inductance value decreases by 10%. The characteristic waveform curve has a rapid change and a steep slope, indicating that the characteristic value change trend can be used to assist in the diagnosis of the degree of inter-turn short-circuit faults in the reactor.

[0083] Therefore, in order to more accurately detect the insulation level and operating status of the reactor, this embodiment uses the changing trend of the characteristic value waveform to assist in judgment. The changing situation of the waveform characteristic value K1 and K2 with the severity of the short circuit is shown in FIG. Figure 11 As shown in the figure, the fault degree is determined as a slight inter-turn short circuit fault, a relatively serious inter-turn short circuit fault, or a severe inter-turn short circuit fault according to the average change rate of the resonant wave peak offset of the reactor to be tested, and a warning / removal signal can be issued only when the distribution change law of the K1 and K2 characteristic values ​​under the corresponding fault degree is met.

[0084] In step S3 and step S4 of this embodiment, based on step S1 and step S2, turn-to-turn short-circuit fault detection is performed based on the measured data of the dry-type air-core reactor to be tested. Specifically, step S3 in this embodiment includes the following steps:

[0085] S31) obtaining an impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested: after the dry-type air-core reactor to be tested is put into operation, collecting frequency parameter measurement values ​​of the resonance point of the impedance logarithmic amplitude spectrum in real time, and preprocessing the collected frequency parameter measurement values, and then comparing the frequency parameter measurement values ​​with the frequency parameter simulation simulation values ​​of the resonance point of the impedance logarithmic amplitude spectrum in the circuit model constructed in step S1 to determine whether the frequency parameter measurement value is an abnormal point, and if so, discard the frequency parameter measurement value; otherwise, retain the frequency parameter measurement value;

[0086] S32) Calculating the resonance peak offset and characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested:

[0087] Similar to the calculation of the resonance peak offset of the impedance logarithmic amplitude spectrum in step S2, when calculating the resonance peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested in this embodiment, the frequency of the resonance peak maximum value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested and the frequencies corresponding to other resonance peaks are obtained, and then the frequency of the corresponding resonance peak maximum value and the frequencies corresponding to other resonance peaks in the impedance logarithmic amplitude spectrum of the normal operation of the dry-type air-core reactor are simulated according to the circuit model to obtain the frequency offset of the resonance peak maximum value and other resonance peaks of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested, and then the average of two or more frequency offsets is calculated to obtain the resonance peak offset;

[0088] Similar to the calculation of the characteristic value of the impedance logarithmic amplitude spectrum in step S2, when calculating the characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested in this embodiment, the absolute value of the impedance logarithmic amplitude spectrum waveform of the current dry-type air-core reactor to be tested is also integrated to obtain the corresponding characteristic waveform, and then the inflection point value A1 of the first stage and the stable values ​​A2 and A3 at the step of the second and third stages in the characteristic waveform are obtained. Finally, the ratio of the stable value A2 at the step of the second stage to the inflection point value A1 of the first stage is calculated as the first characteristic value K1, and the ratio of the stable value A3 at the step of the third stage to the stable value A2 at the step of the second stage is calculated as the second characteristic value K2.

[0089] Step S4 of this embodiment includes the following steps:

[0090] S41) If the resonance peak offset is 0, it indicates that the dry-type air-core reactor to be tested is in a normal state; if the resonance peak offset is greater than 0, it indicates that a turn-to-turn short circuit fault may occur in the dry-type air-core reactor to be tested, and the process jumps to step S42);

[0091] S42) matching the resonance peak offset and characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested with the resonance peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each turn-to-turn short circuit, specifically including:

[0092] S421) matching the resonance peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested with the resonance peak offset interval of the impedance logarithmic amplitude spectrum corresponding to different fault degrees of inter-turn short circuit, and determining the corresponding inter-turn short circuit fault degree according to the matching result;

[0093] Specifically, when the offset of the resonance peak satisfies 0<Δf<2MHZ, it is determined that a slight inter-turn short circuit fault occurs in the dry-type reactor to be tested;

[0094] When the offset of the resonance peak satisfies 2<Δf<20MHZ, it is determined that a serious inter-turn short circuit fault occurs in the dry-type reactor to be tested;

[0095] When the offset of the resonance peak satisfies Δf>20 MHz, it is determined that a serious inter-turn short circuit fault occurs in the dry-type reactor to be tested;

[0096] S421) comparing the characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested with the characteristic value change trend of the impedance logarithmic amplitude spectrum corresponding to the determined inter-turn short-circuit fault degree; if the characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested matches the characteristic value change trend of the impedance logarithmic amplitude spectrum corresponding to the determined inter-turn short-circuit fault degree, then the inter-turn short-circuit fault degree of the dry-type air-core reactor to be tested is the determined inter-turn short-circuit fault degree;

[0097] Specifically, when a minor inter-turn short-circuit fault occurs and the number of short-circuited turns is small, the slight difference between the peaks may also cause misjudgment in actual detection due to on-site interference and measurement errors, causing the average offset of the fault resonance point to vary slightly. In order to more accurately detect the insulation level and operating status of the reactor, this embodiment constructs a characteristic waveform by integrating the absolute value of the waveform, and extracts characteristic values ​​from it to highlight the differences in detection results under different insulation conditions, forming an auxiliary criterion. The setting of the auxiliary criterion verifies the accuracy of the reactor's operating status and plays a role in taking necessary measures in a timely manner to ensure the safe and stable operation of the system.

[0098] Therefore, if it is determined that a slight inter-turn short circuit fault occurs in the dry-type reactor to be tested, Figure 11 Find the trend line corresponding to the first eigenvalue K1 and the second eigenvalue K2 whose inductance value decreases by 0-5%, and judge whether the first eigenvalue K1 and the second eigenvalue K2 of the dry-type air-core reactor to be tested match the corresponding trend line. Specifically, judge whether the first eigenvalue K1 and the second eigenvalue K2 of the dry-type air-core reactor to be tested are both on the corresponding trend line and have the same horizontal coordinate. If so, it is confirmed that a slight inter-turn short circuit fault occurs in the dry-type reactor to be tested. Otherwise, it is considered that a misjudgment may occur, such as Figure 2As shown, return to step S3 to obtain the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested again for re-testing;

[0099] Similarly, if step S421 determines that a relatively serious inter-turn short circuit fault occurs in the dry-type reactor to be tested, and after determining that a serious inter-turn short circuit fault occurs in the dry-type reactor to be tested, the judgment result of step S421 can be confirmed by searching the corresponding characteristic value trend line and determining whether the characteristic value of the dry-type air-core reactor to be tested matches the characteristic value trend line;

[0100] S423) matching the resonance peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested with the resonance peak offset interval of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit at different fault locations in the determined inter-turn short circuit fault degree, and determining the corresponding inter-turn short circuit fault location based on the matching result.

[0101] Specifically, in step S423 of this embodiment, based on the judgment results of step S421 and step S422, the approximate decrease range of the inductance of the dry-type air-core reactor to be tested can be obtained. For example, if it is confirmed that a serious inter-turn short circuit fault occurs in the dry-type reactor to be tested, the approximate decrease range of the inductance is 5-15%.

[0102] Therefore, the set of resonance peak offsets of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit at different fault locations in the corresponding inductance drop range collected in step S2 can be selected to match the resonance peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested, and the fault location corresponding to the closest resonance peak offset is selected as the possible fault location. For example, select Figure 8 The set of resonance peak offsets of the impedance logarithmic amplitude spectrum at different positions where the inductance drops by 10% shown can be used to determine the location of the inter-turn fault of the dry-type air-core reactor to be tested based on the position corresponding to the resonance peak offset that is closest to the resonance peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested.

[0103] Example 2

[0104] This embodiment proposes a dry-type air-core reactor inter-turn short-circuit fault detection system based on the average offset of the resonance peak, including a microprocessor and a computer-readable storage medium connected to each other, and the microprocessor is programmed or configured to execute the dry-type air-core reactor inter-turn short-circuit fault detection method based on the average offset of the resonance peak described in Example 1.

[0105] In summary, the present invention finds that as the frequency increases, the inductive reactance increases and the capacitive reactance decreases, and series-parallel resonance occurs in the internal circuit of the reactor. Moreover, at high frequencies, the voltage drop of the reactor is distributed according to the capacitance. When the impedance logarithmic amplitude spectrum is measured, the frequency of the resonance point in the amplitude spectrum is very sensitive to changes in electrical parameters. Therefore, the operating state of the reactor can be analyzed using the impedance logarithmic amplitude spectrum. Therefore, a method for detecting inter-turn short-circuit faults of dry-type hollow reactors based on the average offset of the resonance peak is proposed. Different peak values ​​generated by resonance are obtained. When the average values ​​of two or more resonance peak offsets under different fault degrees are greater than the set value and the distribution change law of the K1 and K2 characteristic values ​​is met, it is determined whether the dry-type hollow reactor has inter-turn short-circuit faults of different degrees.

[0106] When measuring data, the present invention determines that, when a collective rightward shift in the offset of the resonance peak is detected, the average of two or more resonance peak offsets is calculated, and if the average value of the offsets is within a set value range, and the trend of the auxiliary criteria K1 and K2 is satisfied, the dry-type air-core reactor fault is determined to be one of a minor inter-turn short circuit fault, a more severe inter-turn short circuit fault, or a serious inter-turn short circuit fault. The general range of the inductance drop is then inferred, and based on the curve of the average resonance point offset and the fault location frequency, the reactor layer where the inter-turn short circuit occurs can be determined, i.e., the fault location can be determined. This allows for the timely issuance of an alarm / disconnection signal, prompting a timely diagnosis of the reactor's real-time status and improving sensitivity.

[0107] The simulation results show that the method of the present invention is correct in judgment and has high accuracy, effectiveness and reliability.

[0108] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for detecting inter-turn short-circuit faults in dry-type air-core reactors based on the average offset of resonance peaks, characterized in that: The following steps are involved: Constructing a circuit model of a dry-type air-core reactor, using the circuit model to simulate normal operation of the dry-type air-core reactor and inter-turn short circuits with different fault degrees and fault locations, and obtaining corresponding impedance logarithmic amplitude spectra; Calculate the resonance peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit of the dry-type air-core reactor respectively, wherein the resonance peak offset specifically refers to the offset of the resonance peak of the impedance logarithmic amplitude spectrum compared to the resonance peak of the impedance logarithmic amplitude spectrum during normal operation of the dry-type air-core reactor. When calculating the characteristic value of the impedance logarithmic amplitude spectrum, specifically integrate the absolute value of the impedance logarithmic amplitude spectrum waveform corresponding to the current inter-turn short circuit to obtain the corresponding characteristic waveform, calculate the change trend of the specified position of the characteristic waveform, and obtain the characteristic value corresponding to the current inter-turn short circuit; Obtaining an impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested, and calculating a resonant peak offset and a characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested; If the resonant peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested is greater than a preset threshold, the resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested are matched with the resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit, and the inter-turn short circuit fault location and fault degree of the dry-type air-core reactor to be tested are determined according to the matching results.

2. The method for detecting inter-turn short-circuit faults of dry-type air-core reactors based on the average offset of resonance peaks according to claim 1, characterized in that: Constructing the circuit model of dry-type air-core reactor specifically includes the following steps: Establish a distributed equivalent circuit model of the reactor at high frequencies, calculate the inter-turn capacitance, inter-layer capacitance, stray capacitance to ground, coil self-inductance, and mutual inductance; Write the Kirchhoff current law equation for any node i in the distributed equivalent circuit model of the reactor, then write the voltage and current equations of the inductor and resistor branches adjacent to the node i, and organize them into the form of an admittance matrix. After the node voltage and current are obtained, the inverse of the admittance matrix is ​​calculated to obtain the impedance value.

3. The method for detecting inter-turn short-circuit faults of dry-type air-core reactors based on average offset of resonance peaks according to claim 2, characterized in that: The expression in admittance matrix form is as follows: in, is the admittance matrix of the equivalent circuit model, represents the node voltage difference, Represents the mutual inductance voltage drop.

4. The method for detecting inter-turn short-circuit faults of dry-type air-core reactors based on average offset of resonance peaks according to claim 1, characterized in that: When respectively calculating the resonant peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit of the dry-type air-core reactor, the step of calculating the resonant peak offset of the impedance logarithmic amplitude spectrum includes: Obtain the frequency corresponding to the maximum value of the resonance peak in the impedance logarithmic amplitude spectrum of the dry-type air-core reactor during normal operation Frequencies corresponding to other resonant peaks 、 ... ; Get the frequency corresponding to the maximum value of the resonant peak in the impedance logarithmic amplitude spectrum corresponding to the current inter-turn short circuit Frequencies corresponding to other resonant peaks 、 ... ; Calculate the frequency corresponding to the maximum value of the resonant peak in the impedance logarithmic amplitude spectrum corresponding to the current inter-turn short circuit Relative to frequency Offset , and calculate the frequencies corresponding to other resonant peaks in the impedance logarithmic amplitude spectrum corresponding to the current inter-turn short circuit 、 ... Relative to frequency 、 ... Offset , ... , calculate the offset , , ... The average value of the current inter-turn short circuit is used to obtain the resonance peak offset Δ f .

5. The method for detecting inter-turn short-circuit faults of dry-type air-core reactors based on average offset of resonance peaks according to claim 1, characterized in that: Calculating the changing trend of a specified position of a characteristic waveform includes: Get the inflection point value of the first stage in the characteristic waveform , and the stable values ​​of the steps in the second and third stages of the characteristic waveform 、 ; Calculate the stability value of the step in the second stage and the inflection point value of the first stage The ratio of , calculate the stability value of the step at the third stage The stable value at the step of the second stage The ratio of .

6. The method for detecting inter-turn short-circuit faults of dry-type air-core reactors based on average offset of resonance peaks according to claim 1, characterized in that: After respectively calculating the resonance peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each inter-turn short circuit of the dry-type air-core reactor, the method includes: dividing the resonance peak offset intervals of the impedance logarithmic amplitude spectrum corresponding to inter-turn short circuits of different fault degrees according to the value of the resonance peak offset, and constructing a set of resonance peak offsets of the impedance logarithmic amplitude spectrum corresponding to inter-turn short circuits of different fault locations under the same fault degree; The characteristic values ​​of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit with different fault degrees are fitted to obtain the characteristic value change trend of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit with different fault degrees.

7. The method for detecting inter-turn short-circuit faults of dry-type air-core reactors based on average offset of resonance peaks according to claim 6, characterized in that: When matching the resonance peak offset and characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested with the resonance peak offset and characteristic value of the impedance logarithmic amplitude spectrum corresponding to each turn-to-turn short circuit, including: Match the resonance peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested with the resonance peak offset interval of the impedance logarithmic amplitude spectrum corresponding to different fault degrees of inter-turn short circuit, and determine the corresponding inter-turn short circuit fault degree according to the matching result; Comparing the characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested with the characteristic value change trend of the impedance logarithmic amplitude spectrum corresponding to the determined inter-turn short-circuit fault degree, if the characteristic value of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested matches the characteristic value change trend of the impedance logarithmic amplitude spectrum corresponding to the determined inter-turn short-circuit fault degree, then the inter-turn short-circuit fault degree of the dry-type air-core reactor to be tested is the determined inter-turn short-circuit fault degree; The resonance peak offset of the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested is matched with the set of resonance peak offsets of the impedance logarithmic amplitude spectrum corresponding to the inter-turn short circuit at different fault locations in the determined inter-turn short circuit fault degree, and the corresponding inter-turn short circuit fault location is determined according to the matching result.

8. The method for detecting inter-turn short-circuit faults of dry-type air-core reactors based on average offset of resonance peaks according to claim 1, characterized in that: When obtaining the impedance logarithmic amplitude spectrum of the dry-type air-core reactor to be tested, it includes: real-time collection of the frequency parameter measurement value of the resonant point in the impedance logarithmic amplitude spectrum and preprocessing, and then comparing it with the corresponding frequency parameter simulation value in the circuit model to determine whether the frequency parameter measurement value belongs to an abnormal point. If so, the corresponding data is discarded; otherwise, the corresponding data is retained.

9. A dry-type air-core reactor inter-turn short-circuit fault detection system based on the average offset of the resonance peak, characterized in that: The invention comprises a microprocessor and a computer-readable storage medium connected to each other, wherein the microprocessor is programmed or configured to execute the dry-type air-core reactor inter-turn short-circuit fault detection method based on the average offset of the resonance wave peak according to any one of claims 1 to 8.

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