Method and device for phase checking on the secondary side of a voltage transformer

Abstract

The present invention discloses a method and device for phase verification on the secondary side of a voltage transformer, relating to the technical field of phase angles; the method includes a phase verification step of obtaining a first voltage curve on a first voltage transformer, obtaining a second voltage curve on a second voltage transformer, obtaining the similarity between the first voltage curve and the second voltage curve based on a signature curve, and obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity; the device includes a phase verification module for obtaining a first voltage curve on a first voltage transformer, obtaining a second voltage curve on a second voltage transformer, obtaining the similarity between the first voltage curve and the second voltage curve based on a signature curve, and obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity; obtaining the similarity between the first voltage curve and the second voltage curve based on the signature curve, and further obtaining the phase angle difference between the first voltage curve and the second voltage curve.

Description

Technical Field

[0001] The present invention relates to the technical field of phase angle, and particularly relates to a method and device for phase checking on the secondary side of a voltage transformer. Background Art

[0002] The secondary phase checking work is the last line of defense for verifying whether the wiring of the secondary voltage circuit of the voltage transformer is correct, and provides guarantee for the correctness of the secondary voltage of the equipment.

[0003] At the present stage, wireless secondary phase checking instruments have realized wireless replacing wired and made the voltage phase relationship "visualizable". On the premise that the secondary voltage circuit is correct, the use of the instruments significantly reduces manpower and time. However, when there are errors in the secondary voltage circuit, it still relies on the analysis and judgment of the vector diagram by the staff. In addition, because the current instruments only support the input of single-phase voltage, the wiring needs to be frequently changed during phase checking, and the single-phase displayed vector diagram is also not conducive to the staff to analyze the cause of the error.

[0004] Carry out progressive analysis on the sampled three-phase voltage data, make intelligent judgments and feedback the abnormalities in each link to the operators, so as to provide guidance for the staff when there are errors in the secondary circuit.

[0005] The writer searched, and the search formula was TACD_ALL: (transformer AND voltage curve AND delay), and obtained the following prior art solutions that are relatively close.

[0006] The authorized announcement number is CN102095926B, and the name is a method for automatically detecting power system configuration, hereinafter referred to as Comparative Document 1. This network has a feeder line, which is provided with a plurality of feeder meters and a distribution transformer meter (DTM) coupled thereto, and one or more user meters and / or user configuration modules coupled to the distribution transformer. The method includes the following steps: enabling each feeder meter to transmit a uniquely identifiable signal through the feeder line. The DTM then identifies each of the uniquely identifiable signals and then transmits the phase of each of the uniquely identifiable signals together with a unique DTM identifier to a data collector. The connection relationship between the feeder meter and the distribution transformer meter is obtained by comparing the phase information transmitted by the DTM. The relationship between the user meter and the DTM can also be drawn by enabling each DTM to transmit the DTM identifier to all its corresponding user meters, and the corresponding user meters then transmit the same together with the user meter identifier to the data collector.

[0007] The publication number of the application is CN109842378A, and the name of the communication device is a transformer feedback quadrature voltage-controlled oscillator and its application, hereinafter referred to as Comparative Document 2. It includes a first half circuit and a second half circuit. The first half circuit and the second half circuit respectively include a first coupling capacitor, a second coupling capacitor, an inductive inductor, a PMOS transistor, an NMOS transistor, and a frequency modulation circuit. The bases of the PMOS transistor and the NMOS transistor are respectively connected to the first ends of the first coupling capacitor and the second coupling capacitor. The drain of the PMOS transistor is connected to the first end of the inductive inductor. The gate of the NMOS transistor is connected to the drain of the PMOS transistor. The drain of the NMOS transistor is connected to the gate of the PMOS transistor and the second end of the inductive inductor. The frequency modulation circuit is connected to the drain of the PMOS transistor and the drain of the NMOS transistor.

[0008] The writer learned that:

[0009] In Comparative Document 1, it is possible to determine which phase the DTM is connected to by analyzing the phase angle of the demodulated feeder meter signal.

[0010] In Comparative Document 2, the output load of the transformer feedback quadrature voltage-controlled oscillator 1 can be reduced, and the maximum operating frequency of the transformer feedback quadrature voltage-controlled oscillator 1 can be increased. The frequency-voltage curve of the transformer feedback quadrature voltage-controlled oscillator 1 can be translated, and the logarithmic linear range can be increased and the phase deviation can be corrected at different frequencies.

[0011] The inventor provides an introduction to the prior art solution:

[0012] 1. Types of on-site wiring errors

[0013] Combined with on-site work, three typical incorrect wiring situations existing in the secondary voltage circuit are summarized:

[0014] a. One phase wire and the neutral wire are connected reversely.

[0015] b. Two phase wires are connected reversely. When the V and W phase wires are connected reversely, the three-phase voltages are still symmetrical but not in positive sequence.

[0016] c. All three phases are connected wrongly. Although the three-phase voltages are still in positive sequence, they are out of phase with the system voltages.

[0017] It should be noted that the on-site errors are not limited to the above three types.

[0018] 2. Progressive secondary phase verification method

[0019] 2.1 Obtain sampling data

[0020] The host collects the instantaneous values of the three-phase voltages of the reference operating device, and the slave collects the instantaneous values of the three-phase voltages of the new device. Assuming that the sampling frequencies of the host and the slave are both 1200 Hz, within one power frequency cycle, both the host and the slave can obtain 24 sampling points. Assuming that the instantaneous values of the three-phase voltages of the new device sampled by the slave at the i-th moment within one cycle are U U (i), U V (i), U W (i) (i = 1, 2,..., 24), and the instantaneous values of the three-phase voltages of the reference device sampled by the host at the i-th moment are U u (i), U v (i), U w (i) (i = 1, 2,..., 24).

[0021] 2.2 Progressive judgment process

[0022] Combined with the above types of incorrect wiring, the analysis and judgment are carried out through the following four steps.

[0023] a. Check whether the effective values of the three-phase voltages of the new device are within the normal range.

[0024] According to on-site working experience, the effective values of the three-phase voltages should meet the requirements shown in Equation (1), otherwise, check whether the test wiring or the secondary wiring of the voltage circuit is correct.

[0025]

[0026] b. Check whether the three-phase voltages of the new device are symmetrical.

[0027] If the three-phase voltages are symmetrical, theoretically, the algebraic sum of the instantaneous values of the three-phase voltages is 0. Considering the error of the sampling data, the condition shown in Equation (2) should be met.

[0028] |U U (i) + U V (i) + U W (i)| ≤ 5V (2)

[0029] c. Check whether the three-phase voltages of the new device are positive sequence.

[0030] When the sampling data meets the requirements in Equation (3), the three-phase voltages are positive sequence.

[0031]

[0032] Wherein, U U (i + N / 4) ≥ 0 represents the instantaneous voltage value at a quarter-cycle moment after the i-th sampling point of the U phase; X UV represents the average value of the product of the instantaneous voltages at two sampling moments of the U phase and the V phase. U V (i), UW (i); U V (i + N / 4), U W (i + N / 4); X VW , X WU The meaning of is the same as that described above.

[0033] Taking X UV as an example, for the positive-sequence voltage, the voltage of phase U leads the voltage of phase V by 120°. According to the above calculation method, after phase V rotates counterclockwise by 1 / 4 cycle, it still lags behind phase U by 30° and remains fixed.

[0034] As Figure 10 shown, since phase V always lags behind phase U by 30°, only phase U is labeled and phase V is no longer labeled. During the process of rotating one cycle, assuming that the sampling moment when i = 1 is just the starting point of a sine wave, the U U (i) × U V The positive and negative situations of (i + N / 4) are shown in formula (4).

[0035]

[0036] As Figure 10 shown, the operation results of the sampling points within the labeled area are negative, and the operation results of the sampling points in other areas are positive. After derivation, for the positive-sequence voltage, X UV > 0. Similarly, X VW > 0 and X WU > 0.

[0037] For the negative-sequence voltage, according to the above calculation method, the voltage has X UV < 0, X VW < 0 and X WU < 0.

[0038] If it is determined as negative sequence, the staff needs to check whether the test wiring or the secondary circuit wiring is correct. Reversing any two of the three-phase voltages may cause the phase verification result to be negative sequence.

[0039] Combining the above two patent documents and the existing technical solutions, the inventor hopes to find a new technical route to solve the technical problem of detecting the phase angle difference between two voltage curves. Summary of the Invention

[0040] The technical problem to be solved by the present invention is to provide a method and device for phase verification on the secondary side of a voltage transformer, so as to solve the technical problem of detecting the phase angle difference between two voltage curves.

[0041] To solve the above technical problems, the technical solution adopted by the present invention is: a method for phase checking on the secondary side of a voltage transformer includes a phase checking step, obtaining a first voltage curve on a first voltage transformer, obtaining a second voltage curve on a second voltage transformer, obtaining the similarity between the first voltage curve and the second voltage curve based on a signature curve, and obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity.

[0042] A further technical solution lies in that: the similarity between the first voltage curve and the second voltage curve is the offset of the two voltage curves, that is, the number of sampling points by which the sampling points of the first voltage curve are offset from the corresponding sampling points on the second voltage curve; obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity is multiplying the number of offset sampling points by the phase angle corresponding to one sampling point. The phase angle of half a cycle of the voltage curve is 180°, and the phase angle corresponding to one sampling point is obtained by dividing the phase angle of half a cycle by the number of sampling points within the half cycle.

[0043] A further technical solution lies in that:

[0044]

[0045] Equation (13) is the signature curve, where is the similarity between the first voltage curve and the second voltage curve, C represents the first voltage curve, represents the second voltage curve; i is the i-th sampling point in the first voltage curve, and x i is the signature (κ, κ s ) at the i-th sampling point in the first voltage curve, which consists of the curvature and the derivative of the curvature with respect to the arc length. The horizontal axis is the curvature, and the vertical axis is the derivative of the curvature with respect to the arc length; j is the j-th sampling point in the second voltage curve, is the signature at the j-th sampling point in the second voltage curve represents x i and the magnitude of the intensity between them. The closer the distance, the greater the intensity and the larger the value; is to scale this intensity value to the interval [0, 1]; ∑ j represents the sum of the signature curves of the i-th sampling point in the first voltage curve and all sampling points in the second voltage curve after operations such as comparing the scale function, separation function, and intensity function, is to take the average value of the intensity values of all the above points to obtain the final similarity score; the values of i and j are set as needed. The more the number of values taken, the smaller the value of the phase angle difference corresponding to the deviation of one sampling point in the similarity, and the more accurate the obtained phase angle difference.

[0046] A further technical solution is as follows: Compare using half a cycle of the voltage curve. The value of i is 12, and the value of j is 12.

[0047] A device for phase verification on the secondary side of a voltage transformer includes a phase verification module, which is a program module for obtaining a first voltage curve on a first voltage transformer, obtaining a second voltage curve on a second voltage transformer, obtaining the similarity between the first voltage curve and the second voltage curve based on a signature curve, and obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity.

[0048] A further technical solution is as follows: The phase verification module is also used for the similarity between the first voltage curve and the second voltage curve to be the offset of the two voltage curves, that is, the number of sampling points by which the sampling points of the first voltage curve are offset from the corresponding sampling points on the second voltage curve; obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity is to multiply the number of offset sampling points by the phase angle corresponding to one sampling point. The phase angle of half a cycle of the voltage curve is 180°, and the phase angle corresponding to one sampling point is obtained by dividing the phase angle of half a cycle by the number of sampling points within the half cycle.

[0049] A further technical solution is as follows: The phase verification module is also used for setting the number of sampling points as needed. The more the number of values, the smaller the value of the phase angle difference corresponding to the deviation of one sampling point in the similarity, and the more accurate the obtained phase angle difference.

[0050] A further technical solution is as follows: The number of sampling points for half-cycle sampling is 12.

[0051] A device for phase verification on the secondary side of a voltage transformer includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the corresponding steps are implemented.

[0052] A device for phase verification on the secondary side of a voltage transformer includes a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the corresponding steps are implemented.

[0053] The beneficial effects of adopting the above technical solutions are as follows:

[0054] First, a method for phase verification on the secondary side of a voltage transformer includes a phase verification step of obtaining a first voltage curve on a first voltage transformer, obtaining a second voltage curve on a second voltage transformer, obtaining the similarity between the first voltage curve and the second voltage curve based on a signature curve, and obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity. With this technical solution, the similarity between the first voltage curve and the second voltage curve is obtained based on the signature curve, and then the phase angle difference between the first voltage curve and the second voltage curve is obtained.

[0055] Second, a device for phase verification on the secondary side of a voltage transformer includes a phase verification module, which is a program module for obtaining a first voltage curve on a first voltage transformer, obtaining a second voltage curve on a second voltage transformer, obtaining the similarity between the first voltage curve and the second voltage curve based on a signature curve, and obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity. According to this technical solution, the similarity between the first voltage curve and the second voltage curve is obtained based on the signature curve, and then the phase angle difference between the first voltage curve and the second voltage curve is obtained.

[0056] See the description in the specific implementation part for details. Description of the Drawings

[0057] Figure 1 is the principle block diagram of Embodiment 3 of the present invention;

[0058] Figure 2 is the principle block diagram of Embodiment 4 of the present invention;

[0059] Figure 3 is the curve graph of the signature curve;

[0060] Figure 4 is the first state diagram;

[0061] Figure 5 is the second state diagram;

[0062] Figure 6 is the third state diagram;

[0063] Figure 7 is the fourth state diagram;

[0064] Figure 8 is the fifth state diagram;

[0065] Figure 9 is the curve graph of the similarity;

[0066] Figure 10 is the positive sequence voltage analysis diagram. Specific Implementation Modes

[0067] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation to the present application and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0068] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application may be practiced in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the spirit of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0069] Embodiment 1:

[0070] The present invention discloses a method for phase comparison on the secondary side of a voltage transformer, which includes a phase comparison step:

[0071] Obtain the first voltage curve on the first voltage transformer, obtain the second voltage curve on the second voltage transformer, obtain the similarity between the first voltage curve and the second voltage curve based on the signature curve, and obtain the phase angle difference between the first voltage curve and the second voltage curve based on the similarity.

[0072] The similarity between the first voltage curve and the second voltage curve is the offset of the two voltage curves, that is, the number of sampling points by which the sampling points of the first voltage curve deviate from the corresponding sampling points on the second voltage curve; obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity is to multiply the number of offset sampling points by the phase angle corresponding to one sampling point. The phase angle of half a cycle of the voltage curve is 180°, and the phase angle corresponding to one sampling point is obtained by dividing the phase angle of half a cycle by the number of sampling points in half a cycle.

[0073]

[0074] Equation (13) is the signature curve, where is the similarity between the first voltage curve and the second voltage curve, C represents the first voltage curve, represents the second voltage curve; i is the i-th sampling point in the first voltage curve, x i is the signature (κ, κ s ) at the i-th sampling point in the first voltage curve, which consists of the curvature and the derivative of the curvature with respect to the arc length. The horizontal axis is the curvature, and the vertical axis is the derivative of the curvature with respect to the arc length; j is the j-th sampling point in the second voltage curve, is the signature at the j-th sampling point in the second voltage curve represents the magnitude of the intensity between x i and . The closer the distance, the greater the intensity and the larger the value; is to scale this intensity value to the interval [0, 1]; ∑ j represents the sum of the signature curves of the i-th sampling point in the first voltage curve and all sampling points in the second voltage curve after operations such as comparing the scaling function, separation function, and intensity function, To obtain the final similarity score by taking the average of the intensity values of all the above points; the values of i and j are set as needed. The more the number of values taken, the smaller the value of the phase angle difference corresponding to the deviation of a sampling point in the similarity, and the more accurate the obtained phase angle difference.

[0075] Using half a cycle of the voltage curve for comparison, the value of i is 12 and the value of j is 12.

[0076] Instructions for Use of Embodiment 1:

[0077] In the original power system, the voltage transformer of the existing power equipment is the first voltage transformer, and the voltage transformer of the power equipment newly put into the power system is the second voltage transformer. In current work, it is necessary to test the voltage of the equipment newly put into the power system. Only when there is no phase angle difference between the voltage of the equipment newly put into the power system and the voltage of the existing equipment can it be officially used.

[0078] The voltage transformer can collect the voltage status information of power equipment such as busbars, lines, or transformers.

[0079] The wireless secondary phase detector includes a host and a slave. Place the host of the wireless secondary phase detector beside the first voltage transformer, and place the slave of the wireless secondary phase detector beside the second voltage transformer. The host obtains the first voltage curve and sends it to the processors of the host and the slave. The slave obtains the second voltage curve and sends it to the processors of the slave and the host. Both the host and the slave can perform the next calculation through their own processors.

[0080] The processor obtains the first voltage curve and the second voltage curve, obtains the similarity between the first voltage curve and the second voltage curve based on the signature curve, and obtains the phase angle difference between the first voltage curve and the second voltage curve based on the similarity.

[0081] Among them, the first voltage transformer is wired-connected to the host of the wireless secondary phase detector, the second voltage transformer is wired-connected to the slave of the wireless secondary phase detector, the host and the slave are wirelessly connected, and the voltage transformer, the wireless secondary phase detector itself, and the corresponding communication connection technology are prior arts and will not be elaborated here.

[0082] Embodiment 2:

[0083] The present invention discloses a device for secondary phase detection of a voltage transformer, which includes a phase detection module, and the phase detection module is a program module.

[0084] The phase detection module is used to obtain the first voltage curve on the first voltage transformer, obtain the second voltage curve on the second voltage transformer, obtain the similarity between the first voltage curve and the second voltage curve based on the signature curve, and obtain the phase angle difference between the first voltage curve and the second voltage curve based on the similarity.

[0085] The similarity between the first voltage curve and the second voltage curve is the offset of the two voltage curves, that is, the number of sampling points by which the sampling points of the first voltage curve are offset from the corresponding sampling points on the second voltage curve; the phase angle difference between the first voltage curve and the second voltage curve obtained based on the similarity is the number of offset sampling points multiplied by the phase angle corresponding to one sampling point. The phase angle of half a cycle of the voltage curve is 180°, and the phase angle corresponding to one sampling point is obtained by dividing the phase angle of half a cycle by the number of sampling points in half a cycle.

[0086] Set the number of sampling points as needed. The more the number of values, the smaller the value of the phase angle difference corresponding to the deviation of one sampling point in the similarity, and the more accurate the obtained phase angle difference.

[0087] The number of sampling points in half a cycle is 180°.

[0088] Embodiment 3:

[0089] As Figure 1 shown, the present invention discloses a device for phase verification on the secondary side of a voltage transformer, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of Embodiment 1 are implemented.

[0090] Embodiment 4:

[0091] As Figure 2 shown, the present invention discloses a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the steps in Embodiment 1 are implemented.

[0092] Technical solution description:

[0093] Use the signature curve to check the phase angles of the master and slave machines for phase verification.

[0094] Place the host of the wireless secondary phase verification instrument beside the first voltage transformer, and place the slave of the wireless secondary phase verification instrument beside the second voltage transformer.

[0095] The purpose of the signature curve method is to calculate the similarity of two sine curves, and then calculate the phase angle difference between the two sine waves according to the unique correspondence between the similarity and the deviation angle. In reality, there is only a fixed phase angle difference between the in-phase voltages sampled by the master and slave machines. Taking the U-phase voltages of the host and the slave as an example, combined with the signature curve algorithm, calculate the phase angle difference between them.

[0096] Curvature and the derivative of curvature with respect to arc length are the intrinsic basic properties of a curve and do not change with position.

[0097] As Figure 3As shown, the signature curve consists of the curvature κ of each point and the derivative κ_s of the curvature with respect to the arc length. The curve formed with κ as the abscissa and κ_s as the ordinate is the signature curve.

[0098] Without loss of generality, the equation of the U-phase voltage is taken as:

[0099]

[0100] First, the signature curve of the equation needs to be known, and the signature curve of the U-phase voltage can be obtained through the curvature calculation formula of the curve.

[0101] Through the signature curve method, the similarity comparison of the three-phase voltages at the same moment between the host and the slave can be completed. Next, the corresponding relationship between the similarity and the phase difference needs to be found. Assuming there is a deviation between the host and the slave, the relationship between the U-phase of the host and the u-phase of the slave is analyzed using the signature curve, and the same applies to the other two phases.

[0102] 1. Taking the U-phase voltage of the host as the reference, calculate the similarity corresponding to the different phase differences between the U-phase of the host and the u-phase of the slave.

[0103] The signature curve does not consider the position where the curve is located. For simplicity, taking U Uti = u Um sin(ωt i ) represents the U-phase voltage of the host, and taking represents the u-phase voltage of the slave. Without loss of generality, keep the host voltage fixed and translate the slave voltage to calculate the similarity at different phase angles.

[0104] As Figure 4 shown, taking the point in the host where the voltage value is 0 and there is a tendency to move in the positive direction as the first point, that is, the rightmost point in the dashed box in the figure. The curves within the dashed rectangular box are the curves that need to be continuously compared between the host (solid line) and the slave (dashed line). The abscissa is the phase angle, and the ordinate is the voltage value.

[0105] 2. Select half a cycle of the U-phase voltage of the host and compare it with the data within one cycle of the u-phase voltage of the slave.

[0106] 3. During the translation process, as the phase difference between the U-phase voltage of the host and the u-phase voltage of the slave increases, the similarity between the U-phase voltage of the host and the u-phase voltage of the slave gradually decreases.

[0107] As Figure 5 shown, when the phase difference is half a cycle, the first critical point is reached. The similarity is reflected by the closeness of the signature curves corresponding to these two curves. The closer the signature curves fit, the higher the similarity. At this time, the curvatures of the U-phase voltage of the host and the u-phase voltage of the slave are the same, but the derivatives of the curvature with respect to the arc length are exactly opposite, and the similarity reaches the lowest point. The abscissa is the phase angle, and the ordinate is the voltage value.

[0108] 4. Because the sine function has symmetry, the final similarity is not a monotonic function, and it is impossible to determine exactly what the phase difference is.

[0109] As Figure 6 shown, at this time, it is necessary to observe the derivative of the slave machine u-phase voltage compared with the U-phase. If it shows a downward trend, it means that the U-phase voltage is in the first half cycle of comparing with the slave machine phase voltage, and the phase difference is Δx; if it shows an upward trend, it means that the host U-phase voltage is in the second half cycle of comparing with the slave machine u-phase voltage, and the offset is 2π - Δx. The abscissa is the phase angle, and the ordinate is the voltage value.

[0110] 5. Due to the periodicity and self-symmetry of the sine function, when the offset exceeds half a cycle and continues to gradually increase, the slave machine u-phase voltage compared with the host U-phase voltage is equivalent to the host U-phase voltage starting to compare backwards with the slave machine u-phase voltage.

[0111] As Figure 7 shown, for example, the dotted line and the solid curve in the figure are the slave machine u-phase voltages with a deviation of 2 / 5 and 3 / 5 of a cycle from the host U-phase voltage respectively. It can be seen that they are symmetric, that is, their similarities with the U-phase voltage are the same. The abscissa is the phase angle, and the ordinate is the voltage value.

[0112] As Figure 8 shown, as the offset continues to increase, the similarity also begins to gradually increase. When the offset reaches one cycle, the similarity reaches the maximum of 1. In this way, the similarity is monotonic in each half cycle. When the relationship between the similarity and the offset from 0 to π is calculated, according to the above symmetry, the similarity for the offset from π to 2π can be known. The abscissa is the phase angle, and the ordinate is the voltage value.

[0113] 6. Finally, the relationship between the offset and the similarity is obtained, as shown in Table 1. By inversely deducing the offset between the two curves through the similarity, the phase angle difference is finally obtained.

[0114] As Figure 9 shown, combining the image and the derivative of the voltage with respect to the angle, the phase difference can be finally obtained.

[0115] Table 1: Comparison table of sampling point deviation - similarity

[0116] Sampling point deviation 0 1 2 3 4 5 Similarity 0.9902 0.9245 0.8645 0.8014 0.7352 06671 Sampling point deviation 6 7 8 9 10 11 Similarity 0.5964 0.5255 0.4577 0.3917 0.3284 0.2681 Sampling point deviation 12 13 14 15 16 17 Similarity 0.2680 0.3288 0.3900 0.4566 0.5169 0.5981 Sampling point deviation 18 19 20 21 22 23 Similarity 0.6598 0.7250 0.7974 0.8601 0.9231 0.9955

[0117] And 24 sampling points correspond to a complete cycle, and the phase deviation can be reflected in the deviation of the sampling points.

[0118] After obtaining the above results, an exact similarity can be obtained through actual data, and the specific deviation in the number of sampling points can be known through the similarity. The value of the phase deviation can be known through the following formula.

[0119]

[0120] In formula (6), i is the point deviation value of sampling, is the phase difference.

[0121] Advantages of using the signature curve to analyze the phase difference between the master and slave machines:

[0122] 1. The signature curve can weaken the influence on the phase difference judgment when errors occur in the peak value in the phase comparison.

[0123] 2. For this problem, through the similarity at 24 points within one cycle, according to the monotonicity of the similarity graph, the phase difference corresponding to the similarity outside these 24 points can be deduced, and the accuracy will be higher.

[0124] 3. This method can also show a stable solution when facing a more complex system curve. This algorithm mainly combines the properties of trigonometric functions with the signature curve to complete the algorithm.

[0125] When an anomaly exists, through the above steps, the type of the phase difference can be located and fed back to the staff, which is convenient for the staff to find problems targeted.

[0126] The implementation steps of the algorithm will be introduced in detail below. Let the equations of the host voltage and the slave voltage be

[0127] U Uti =u Um sin(ωt i )

[0128] and

[0129]

[0130] First, define the comparison scale function:

[0131]

[0132] In formula (7):

[0133]

[0134]

[0135] C and are the signature curves corresponding to the voltage curves of the master and slave machines to be compared respectively (the signature curve of the host voltage curve is composed of the curvature κ of the voltage at each point and the derivative κ of the curvature with respect to the arc lengths Composed in the form of (κ i , κ i s ). The signature curve of the slave voltage curve consists of the curvature of the voltage at each point and the derivative of the curvature with respect to the arc length and is in the form of κ i is the curvature at the i-th sampling point of the master voltage, is the derivative of the curvature with respect to the arc length at the i-th sampling point of the master voltage; is the curvature at the i-th sampling point of the slave voltage, is the derivative of the curvature with respect to the arc length at the i-th sampling point of the slave voltage). The comparison scale is to measure the maximum variation of the curvature and the derivative of the curvature with respect to the arc length along the curves between the two curves.

[0136] Next, define the separation function of the two curves:

[0137]

[0138] Take two points x and x = (κ i , κ i s ) is a point on the signature curve of the master voltage curve, is a point on the signature curve of the slave voltage curve. i represents the i-th sampling point (their abscissa is the curvature κ, and the ordinate is the derivative of the curvature with respect to the arc length κ s ), x ∈ C, What the separation function represents is the tightness between each point on the two signature curves. It can be seen from the formula that when the distance between two points on the curve is greater than the threshold given by the comparison scale function, it means that there may not be a large connection between the two points. Set the separation scale between these two points to infinity. Of course, if the distance between two points is very close, it will lead to a very large overall strength.

[0139] Now, it is necessary to calculate the strength function between the two curves:

[0140]

[0141]

[0142] In Equation (11), r > 0 and is a constant, and ε > 0 is a very small constant.

[0143] In Equation (12), The distance between the signature curve of the upsampled points of the host voltage curve and the signature curve corresponding to the upsampled points of the slave voltage curve. To avoid the intensity function being infinite due to the denominator being 0. This function represents that the closer the distance between two points, the greater the intensity between the two points, and the intensity between the two points is inversely proportional to the separation function, and its value range is in [0, ∞].

[0144] Next, it is necessary to calculate the overall intensity between the two curves and scale it to between [0, 1] (this is the function for finally calculating the similarity):

[0145]

[0146] In Equation (13), the scaled values are averaged over the number of points of the two curves respectively, ∑ j It means to select the i-th sampling point in the host voltage and sum up the signature curves of all sampling points of the slave voltage after operations such as comparing the scale function, separation function, and intensity function. It represents taking the average after performing the above operations on all points in the host to obtain the final similarity score. We need to scale the final score within the interval [0, 1], and the scaling function is as follows:

[0147]

[0148] In Equation (14), the parameter B will affect the distribution of the final similarity score along the interval [0, 1].

[0149] After the internal operation of this application for a period of time, the beneficial points feedback by on-site technicians are as follows:

[0150] Based on the signature curve, obtain the similarity between the first voltage curve and the second voltage curve, and then obtain the phase angle difference between the first voltage curve and the second voltage curve.

[0151] Currently, the technical solution of the present invention has been pilot-tested, that is, a small-scale test before large-scale mass production; after the pilot test, user usage research has been carried out on a small scale, and the research results show a high user satisfaction; now preparations have begun for the formal production and industrialization of the product (including research on intellectual property risk early warning).

Claims

1. A method for phase verification on the secondary side of a voltage transformer, characterized in that: Including a phase comparison step, obtaining a first voltage curve on a first potential transformer, obtaining a second voltage curve on a second potential transformer, obtaining the similarity between the first voltage curve and the second voltage curve based on a signature curve, and obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity.

2. The method for phase verification on the secondary side of a voltage transformer according to claim 1, wherein: The similarity between the first voltage curve and the second voltage curve is the offset of the two voltage curves, that is, the number of sampling points by which the sampling points of the first voltage curve are offset from the corresponding sampling points on the second voltage curve; obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity is multiplying the number of offset sampling points by the phase angle corresponding to one sampling point. The phase angle of a half cycle of the voltage curve is 180°, and the phase angle corresponding to one sampling point is obtained by dividing the phase angle of the half cycle by the number of sampling points in the half cycle.

3. The method for phase comparison on the secondary side of a potential transformer according to claim 1, wherein: Equation (13) is the signature curve, where is the similarity between the first voltage curve and the second voltage curve. C represents the first voltage curve, represents the second voltage curve; i is the i-th sampling point in the first voltage curve, and x i is the signature at the i-th sampling point in the first voltage curve, which is composed of curvature and the derivative of curvature with respect to arc length. The horizontal axis is curvature, and the vertical axis is the derivative of curvature with respect to arc length; j is the j-th sampling point in the second voltage curve, is the signature at the j-th sampling point in the second voltage curve; represents the intensity magnitude between x i and . The closer the distance, the greater the intensity and the larger the value; is to scale this intensity value to the interval [0, 1]; ∑ means to sum the signature curves of the i-th sampling point in the first voltage curve and all sampling points in the second voltage curve after operations of comparing the scale function, separation function, and intensity function, j is to take the average value of the intensity values of all the above sampling points to obtain the final similarity score; the values of i and j are set as needed. The more the number of values taken, the smaller the numerical value of the phase angle difference corresponding to the deviation of one sampling point in the similarity, and the more accurate the obtained phase angle difference. is to take the average value of the intensity values of all the above sampling points to obtain the final similarity score; the values of i and j are set as needed. The more the number of values taken, the smaller the numerical value of the phase angle difference corresponding to the deviation of one sampling point in the similarity, and the more accurate the obtained phase angle difference.

4. The method for phase verification on the secondary side of a voltage transformer according to claim 3, characterized in that: Use half a cycle of the voltage curve for comparison, where the value of i is 12 and the value of j is 12.

5. A device for phase checking on the secondary side of a voltage transformer, characterized in that: Including a phase comparison module, which is a program module for obtaining a first voltage curve on a first potential transformer, obtaining a second voltage curve on a second potential transformer, obtaining the similarity between the first voltage curve and the second voltage curve based on a signature curve, and obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity.

6. The device for phase checking on the secondary side of a voltage transformer according to claim 5, characterized in that: The phase comparison module is further configured such that the similarity between the first voltage curve and the second voltage curve is the offset of the two voltage curves, that is, the number of sampling points by which the sampling points of the first voltage curve are offset from the corresponding sampling points on the second voltage curve; obtaining the phase angle difference between the first voltage curve and the second voltage curve based on the similarity is multiplying the number of offset sampling points by the phase angle corresponding to one sampling point. The phase angle of a half cycle of the voltage curve is 180°, and the phase angle corresponding to one sampling point is obtained by dividing the phase angle of the half cycle by the number of sampling points in the half cycle.

7. The device for secondary side phase verification of a voltage transformer according to claim 6, characterized in that: The phase comparison module is further configured to set the number of sampling points as needed. The more the number of values, the smaller the value of the phase angle difference corresponding to a deviation of one sampling point in the similarity, and the more accurate the obtained phase angle difference.

8. The device for phase checking on the secondary side of a voltage transformer according to claim 6, characterized in that: The number of sampling points in the half cycle is 12.

9. A device for phase checking on the secondary side of a voltage transformer, comprising a memory, a processor, and a computer program stored in the memory and operable on the processor, characterized in that: When the processor executes the computer program, the corresponding steps in any one of claims 1 to 4 are implemented.

10. A device for phase checking on the secondary side of a voltage transformer includes a computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by the processor, the corresponding steps in any one of claims 1 to 4 are implemented.

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