Synchronous sampling method and device self-adaptive to current direction and medium

Abstract

The invention relates to a current direction self-adaptive synchronous sampling method and device and a medium, and the method comprises the following steps: injecting a superposed signal for a secondary cable, the superposed signal comprising a power frequency alternating current signal and a high-frequency signal; a current signal of a secondary cable is acquired through a synchronous sampling device, the synchronous sampling device sleeves the secondary cable and comprises a first acquisition unit, a magnetic ring and a second acquisition unit which are coaxially arranged in sequence, the first acquisition unit, the magnetic ring and the second acquisition unit are annular and open, the annular radius and the opening position of the first acquisition unit, the magnetic ring and the second acquisition unit are consistent, and the two acquisition units synchronously acquire the current signal; signal frequency components of the current signals collected by the two collection units are compared, and the current direction is determined in a self-adaptive mode; and the current direction and the collected current signal are combined to complete secondary cable current signal sampling. Compared with the prior art, the method has the advantages of simplicity in use, capability of adaptively determining the current direction and the like.

Description

Technical Field

[0001] The invention relates to the technical field of relay protection automation of power systems, and in particular to a synchronous sampling method, equipment and medium for adaptive current direction. Background Art

[0002] The secondary system of the power system refers to a low-voltage electrical system that monitors, controls, adjusts, and protects the operation of the primary electrical equipment and provides operating conditions for the operation and maintenance dispatching personnel. During the debugging, operation and maintenance, and testing of the secondary power system, it is necessary to measure and record the amplitude and phase of the relevant current and voltage under the corresponding operating conditions, and then judge whether the secondary system wiring is correct and whether the device functions intact.

[0003] At present, in load tests, staggered tests and other work, the current clamps used in digital volt-ampere phase meters must be measured strictly according to polarity, that is, the direction of current inflow and outflow cannot be wrong, otherwise the collected phase will be incorrect. This not only adds more workload to on-site operators, but also poses the risk of measurement errors.

[0004] CN115932368A discloses a method for judging the direction of the current loop of the main transformer differential protection based on the same phase, and uses the algorithm θ=n*30°-180° to judge the correctness of the secondary connection of the CT polarity of the current loop on each side of the main transformer differential protection. However, this method still relies on the same phase marking to realize the advanced application of polarity judgment, which is not simple and convenient enough in practical applications.

[0005] CN110244177A discloses a CT polarity tester and test method based on waveform discrimination, which uses waveforms to judge the plus polarity and minus polarity, and can test the CT polarity without disconnecting the CT secondary circuit. However, this method is only applicable to judging whether the wiring on both sides is minus polarity, and is not applicable to polarity judgment under load. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a synchronous sampling method, device and medium for adaptive current direction.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] According to a first aspect of the present invention, a synchronous sampling method for adaptive current direction is provided, the method comprising the following steps:

[0009] Injecting a superimposed signal into the secondary cable, wherein the superimposed signal includes an industrial frequency alternating current signal and a high frequency signal;

[0010] The current signal of the secondary cable is collected by a synchronous sampling device, wherein the synchronous sampling device is put on the secondary cable and comprises a first collection unit, a magnetic ring and a second collection unit which are coaxially placed in sequence, the first collection unit, the magnetic ring and the second collection unit are all ring-shaped and open-designed, and the ring radius and opening position of the three are consistent, and the two collection units synchronously collect the current signal;

[0011] Compare the signal frequency components of the current signals collected by the two collection units and adaptively determine the current direction;

[0012] The secondary cable current signal sampling is completed by combining the current direction and the collected current signal.

[0013] If the first acquisition unit acquires the power frequency signal and the high frequency signal, and the second acquisition unit acquires only the power frequency signal, the current direction is flowing into the first acquisition unit and flowing out of the second acquisition unit;

[0014] If the second acquisition unit acquires the power frequency signal and the high frequency signal, and the first acquisition unit acquires only the power frequency signal, the current direction is flowing into the second acquisition unit and flowing out of the first acquisition unit.

[0015] The method also includes a temperature compensation strategy: the synchronous sampling device corrects the sampling through temperature compensation to improve the sampling accuracy. The relationship between the compensated sampling accuracy and the temperature is expressed as:

[0016] ΔA=A0+kΔT

[0017] Among them, ΔA is the change in accuracy after compensation, A0 is the initial accuracy, k is the temperature coefficient after compensation, and ΔT is the temperature change. The temperature coefficient is determined according to the change in magnetic permeability and resistance, and the relationship is:

[0018] k=f(α,β)

[0019] Where α is the temperature coefficient of magnetic permeability, β is the temperature coefficient of resistance,

[0020] μ t =μ0(1+αΔT)

[0021] R t =R0(1+βΔT)

[0022] Among them, μ t is the magnetic permeability after temperature change, μ0 is the initial magnetic permeability, ΔT is the temperature change, R t is the resistance after temperature change, and R0 is the initial resistance.

[0023] The method also includes an automatic control strategy:

[0024] When the synchronous sampling device and the injection signal have communication conditions, an active control strategy is adopted, and the synchronous sampling device communicates with the injection signal. The synchronous sampling device issues a command to close the injection signal and stop sampling according to its own temperature conditions when the temperature exceeds the preset range;

[0025] When there is no communication condition between the synchronous sampling device and the injected signal, a passive control strategy is adopted. The synchronous sampling device performs temperature compensation according to the change of its own temperature. When the compensated temperature range is within the preset range, the current sampling result is output. When it exceeds the preset range, an alarm is issued and the signal injection is manually stopped.

[0026] The method also includes synchronous acquisition verification:

[0027] Determine whether the time difference between the first acquisition unit and the second acquisition unit when acquiring a current amplitude extreme value meets the following conditions:

[0028] L=E*|t1-t2|

[0029] Wherein, t1 and t2 are the times when the first acquisition unit and the second acquisition unit acquire a current amplitude extreme value, respectively, E is a fixed value of the current propagation speed, and L is the distance between the first acquisition unit and the second acquisition unit;

[0030] When the above conditions are not met, the synchronization timekeeping clocks of the first acquisition unit and the second acquisition unit are corrected to ensure synchronous acquisition.

[0031] The two acquisition units adopt PCB type Rogowski coils.

[0032] The magnetic core material of the magnetic ring is nickel-zinc ferrite.

[0033] The annular radius of the first acquisition unit, the magnetic ring and the second acquisition unit is determined according to the radius of the secondary cable, ensuring that the synchronous sampling device is put on the secondary cable without contact and the intermediate gap is smaller than a preset size.

[0034] According to a second aspect of the present invention, there is provided an electronic device, comprising a memory and a processor, wherein a computer program is stored in the memory, and the method described above is implemented when the processor executes the program.

[0035] According to a third aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, wherein the program implements the method described above when executed by a processor.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) Easy to use: The structure of the present invention adopts open collection, which is easy to install. It does not need to check the current direction for calibration, and can automatically calibrate the current direction based on the current frequency component characteristic analysis.

[0038] (2) High safety: The method of the present invention has a dual sampling mechanism and can perform temperature compensation to achieve self-calibration and adjustment optimization of sampling accuracy.

[0039] (3) High suppression efficiency: The present invention is not only suitable for the case of fixed superposition signals, but also provides self-modulation capability for uncertain frequencies. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural diagram of the synchronous sampling device of the present invention;

[0041] Figure 2 It is the principle diagram of the synchronous sampling device of the present invention;

[0042] Figure 3 This is a schematic diagram of the temperature compensation and automatic control principle of the synchronous sampling device of the present invention. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0044] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0045] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0046] Example 1

[0047] This embodiment provides a synchronous sampling device, such as Figure 1 As shown, the synchronous sampling device is put on the secondary cable, and includes a first acquisition unit, a magnetic ring, and a second acquisition unit coaxially placed in sequence. Among them, the first acquisition unit, the magnetic ring, and the second acquisition unit are all annular and open, and the annular radius and opening position of the three are consistent. The two acquisition units synchronously collect current signals, and the function of the open magnetic ring is to suppress high-frequency signals.

[0048] In this embodiment, the two acquisition units use PCB type Rogowski coils, which can ensure that the two coils have good consistency. The accuracy can reach 0.2 level through mutual calibration of the two acquisition units. The Rogowski coil can measure frequency components from 0.1 Hz to several MHz.

[0049] The core material of the magnetic ring is nickel-zinc ferrite, which has low magnetic permeability and high saturation magnetic induction intensity, but will have greater loss at high frequencies. The applicable frequency range of the magnetic ring is between tens of hertz and several kilohertz, which meets the needs of secondary current measurement.

[0050] The acquisition accuracy requires that the size of the acquisition unit and the size of the secondary cable are as consistent as possible to avoid too many gaps and inaccurate measurements. The annular radius of the first acquisition unit, the magnetic ring, and the second acquisition unit is determined according to the radius of the secondary cable to ensure that the synchronous sampling device is put on the secondary cable without contact and the gap in the middle is smaller than the preset size. In this embodiment, in order to adapt to the typical 2.5 square millimeter secondary cable, the size of the magnetic ring and the acquisition unit is selected to be 3.5 square millimeters.

[0051] Example 2

[0052] This embodiment provides a synchronous sampling method for adaptive current direction, the method comprising the following steps:

[0053] S1 is to inject a superimposed signal into the secondary cable. The superimposed signal includes an industrial frequency AC current signal and a high frequency (or N times frequency) signal.

[0054] S2, collecting the current signal of the secondary cable by the synchronous sampling device as described in Example 1, the principle of which is as follows Figure 2 shown.

[0055] S3, comparing the signal frequency components of the current signals collected by the two collection units, and adaptively determining the current direction.

[0056] If the first acquisition unit acquires the power frequency signal and the high frequency signal, and the second acquisition unit acquires only the power frequency signal, the current direction is flowing into the first acquisition unit and flowing out of the second acquisition unit;

[0057] If the second acquisition unit acquires the power frequency signal and the high frequency signal, and the first acquisition unit acquires only the power frequency signal, the current direction is flowing into the second acquisition unit and flowing out of the first acquisition unit.

[0058] S4, complete the secondary cable current signal sampling in combination with the current direction and the collected current signal.

[0059] S5, temperature compensation

[0060] The magnetic ring has high stability and durability and can maintain its magnetic properties for a long time. Under correct use and storage conditions, the magnetic ring will not usually be damaged. However, if it encounters overheating, it will cause inaccurate measurements and need to be compensated.

[0061] (1) Effect of temperature on magnetic permeability

[0062] When the temperature changes, the relationship between magnetic permeability and temperature can be approximately described by formula (1), where μ t is the magnetic permeability after temperature change, μ0 is the initial magnetic permeability, α is the temperature coefficient of magnetic permeability, and ΔT is the temperature change.

[0063] μt =μ0(1+αΔT) (1)

[0064] (2) Effect of temperature on coil resistance

[0065] When the temperature changes, the relationship between the wire resistance and temperature of the Rogowski coil can be approximately described by formula (2), where R t is the resistance after temperature change, R0 is the initial resistance, β is the temperature coefficient of resistance, and ΔT is the temperature change.

[0066] R t =R0(1+βΔT) (2)

[0067] (3) Temperature compensation

[0068] In order to reduce the influence of temperature on the accuracy of the Rogowski coil, temperature compensation technology is used. The relationship between the accuracy and temperature after compensation can be expressed by formula (3), where ΔA is the change in accuracy after compensation, A0 is the initial accuracy, k is the temperature coefficient after compensation, and ΔT is the temperature change.

[0069] ΔA=A0+kΔT (3)

[0070] The temperature coefficient takes full account of the changes in magnetic permeability and resistance, and the relationship is:

[0071] k=f(α,β) (4)

[0072] Temperature compensation schematic diagram Figure 3 shown.

[0073] S6, automatic temperature control

[0074] S61, when the synchronous sampling device and the injection signal have communication conditions, an active control strategy is adopted, the synchronous sampling device communicates with the injection signal, and the synchronous sampling device issues a command to turn off the injection signal and stop sampling according to its own temperature condition when the temperature exceeds a preset range;

[0075] S62, when there is no communication condition between the synchronous sampling device and the injection signal, a passive control strategy is adopted. The synchronous sampling device performs temperature compensation according to the change of its own temperature. When the compensated temperature range is within the preset range, the current sampling result is output. When it exceeds the preset range, an alarm is issued and the signal injection is manually stopped.

[0076] S7, synchronous acquisition and verification

[0077] Determine whether the time difference between the first acquisition unit and the second acquisition unit when acquiring a current amplitude extreme value meets the following conditions:

[0078] L=E*|t1-t2| (5)

[0079] Wherein, t1 and t2 are the times when the first acquisition unit and the second acquisition unit acquire a current amplitude extreme value, respectively, E is a fixed value of the current propagation speed, and L is the distance between the first acquisition unit and the second acquisition unit;

[0080] When the above conditions are not met, the synchronization timekeeping clocks of the first acquisition unit and the second acquisition unit are corrected to ensure synchronous acquisition.

[0081] Example 3

[0082] When communication conditions are met, temperature protection control can be automatically achieved between the synchronous sampling device and the signal injection device. The sampling process specifically includes the following steps:

[0083] (1) The first acquisition unit and the second acquisition unit simultaneously measure the current passing through the secondary cable.

[0084] (2) If the first acquisition unit has power frequency and double frequency signals, and the second acquisition unit has only power frequency signals, the current direction is from the first acquisition unit to the second acquisition unit; if the first acquisition unit has only power frequency, and the second acquisition unit has power frequency signals and double frequency signals, the current direction is from the second acquisition unit to the first acquisition unit.

[0085] (3) The acquisition unit corrects the sampling through temperature compensation to improve the sampling accuracy.

[0086] (4) When the temperature is too high and affects the linear compensation of the sampling accuracy, the signal injection is actively stopped through communication, and the measurement is performed again after the temperature drops to the linear compensation range.

[0087] Example 4

[0088] When communication conditions are not met, the synchronous sampling device makes self-judgment and analyzes the results. If the compensation effect is not satisfactory, an alarm is issued. The sampling process specifically includes the following steps:

[0089] (1) The first acquisition unit and the second acquisition unit simultaneously measure the current passing through the secondary cable.

[0090] (2) If the first acquisition unit has power frequency and double frequency signals, and the second acquisition unit has only power frequency signals, the current direction is from the first acquisition unit to the second acquisition unit; if the first acquisition unit has only power frequency, and the second acquisition unit has power frequency signals and double frequency signals, the current direction is from the second acquisition unit to the first acquisition unit.

[0091] (3) The acquisition unit corrects the sampling through temperature compensation to improve the sampling accuracy.

[0092] (4) When the temperature is too high and affects the linear compensation of the sampling accuracy, an alarm is issued to inform that the sampling value is inaccurate, and a manual notification is given to stop signal injection. The measurement can be carried out again after the temperature drops to the linear compensation range.

[0093] Example 5

[0094] The electronic device of the present invention includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or loaded from a storage unit into a random access memory (RAM). In the RAM, various programs and data required for device operation can also be stored. The CPU, ROM and RAM are connected to each other via a bus. An input / output (I / O) interface is also connected to the bus.

[0095] Multiple components in the device are connected to the I / O interface, including: input units, such as keyboards, mice, etc.; output units, such as various types of displays, speakers, etc.; storage units, such as disks, optical disks, etc.; and communication units, such as network cards, modems, wireless communication transceivers, etc. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunication networks.

[0096] The processing unit performs the various methods and processes described above, such as methods S1 to S7. For example, in some embodiments, methods S1 to S7 may be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and / or installed on the device via a ROM and / or a communication unit. When the computer program is loaded into the RAM and executed by the CPU, one or more steps of methods S1 to S7 described above may be performed. Alternatively, in other embodiments, the CPU may be configured to execute methods S1 to S7 in any other appropriate manner (e.g., by means of firmware).

[0097] The functions described above herein may be performed at least in part by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), and the like.

[0098] The program code for implementing the method of the present invention can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partially on the machine, partially on the machine as a stand-alone software package and partially on a remote machine, or entirely on a remote machine or server.

[0099] In the context of the present invention, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0100] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A synchronous sampling method for adaptive current direction, characterized in that: The method comprises the following steps: Injecting a superimposed signal into the secondary cable, wherein the superimposed signal includes an industrial frequency alternating current signal and a high frequency signal; The current signal of the secondary cable is collected by a synchronous sampling device, wherein the synchronous sampling device is put on the secondary cable and comprises a first collection unit, a magnetic ring and a second collection unit which are coaxially placed in sequence, the first collection unit, the magnetic ring and the second collection unit are all ring-shaped and open-designed, and the ring radius and opening position of the three are consistent, and the two collection units synchronously collect the current signal; Compare the signal frequency components of the current signals collected by the two collection units and adaptively determine the current direction; The secondary cable current signal sampling is completed by combining the current direction and the collected current signal.

2. The method for synchronous sampling of adaptive current direction according to claim 1, characterized in that: If the first acquisition unit acquires the power frequency signal and the high frequency signal, and the second acquisition unit acquires only the power frequency signal, the current direction is flowing into the first acquisition unit and flowing out of the second acquisition unit; If the second acquisition unit acquires the power frequency signal and the high frequency signal, and the first acquisition unit acquires only the power frequency signal, the current direction is flowing into the second acquisition unit and flowing out of the first acquisition unit.

3. The method for synchronous sampling of adaptive current direction according to claim 1, characterized in that: The method also includes a temperature compensation strategy: the synchronous sampling device corrects the sampling through temperature compensation to improve the sampling accuracy. The relationship between the compensated sampling accuracy and the temperature is expressed as: ΔA=A0+kΔT Among them, ΔA is the change in accuracy after compensation, A0 is the initial accuracy, k is the temperature coefficient after compensation, and ΔT is the temperature change. The temperature coefficient is determined according to the change in magnetic permeability and resistance, and the relationship is: k=f(α,β) Where α is the temperature coefficient of magnetic permeability, β is the temperature coefficient of resistance, m t =μ0(1+αΔT) R t =R0(1+βΔT) Among them, μ t is the magnetic permeability after temperature change, μ0 is the initial magnetic permeability, ΔT is the temperature change, R t is the resistance after temperature change, and R0 is the initial resistance.

4. The method for synchronous sampling of adaptive current direction according to claim 1, characterized in that: The method also includes an automatic control strategy: When the synchronous sampling device and the injection signal have communication conditions, an active control strategy is adopted, and the synchronous sampling device communicates information with the injection signal. The synchronous sampling device issues a command to close the injection signal and stop sampling according to its own temperature conditions when the temperature exceeds the preset range; When there is no communication condition between the synchronous sampling device and the injected signal, a passive control strategy is adopted. The synchronous sampling device performs temperature compensation according to the change of its own temperature. When the compensated temperature range is within the preset range, the current sampling result is output. When it exceeds the preset range, an alarm is issued and the signal injection is manually stopped.

5. The method for synchronous sampling of adaptive current direction according to claim 1, characterized in that: The method also includes synchronous acquisition verification: Determine whether the time difference between the first acquisition unit and the second acquisition unit when acquiring a current amplitude extreme value meets the following conditions: L=E*|t1-t2| Wherein, t1 and t2 are the times when the first acquisition unit and the second acquisition unit acquire a current amplitude extreme value, respectively, E is a fixed value of the current propagation speed, and L is the distance between the first acquisition unit and the second acquisition unit; When the above conditions are not met, the synchronization timekeeping clocks of the first acquisition unit and the second acquisition unit are corrected to ensure synchronous acquisition.

6. The method for synchronous sampling of adaptive current direction according to claim 1, characterized in that: The two acquisition units adopt PCB type Rogowski coils.

7. The method for synchronous sampling of adaptive current direction according to claim 1, characterized in that: The magnetic core material of the magnetic ring is nickel-zinc ferrite.

8. The method for synchronous sampling of adaptive current direction according to claim 1, characterized in that: The annular radius of the first acquisition unit, the magnetic ring and the second acquisition unit is determined according to the radius of the secondary cable, ensuring that the synchronous sampling device is put on the secondary cable without contact and the intermediate gap is smaller than a preset size.

9. An electronic device comprising a memory and a processor, wherein a computer program is stored in the memory, wherein: When the processor executes the program, the method according to any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

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