Method, system, device and medium for calibrating protection current based on measurement current
Through the calibration method of measuring current on the protection current, the problem of sampling accuracy and range coexisting in power grid protection is solved, and more efficient sampling accuracy and range are achieved, reducing the number of optional AC modules.
Patent Information
- Application Number
- CN202411882296.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2025-03-28
AI Technical Summary
In the existing power grid protection, the sampling accuracy of the protective current transformer does not coexist with the sampling range, which makes it difficult to ensure both sampling accuracy and range when the AC module is reduced.
By calibrating the protection current based on the measurement current, a three-phase measurement current sampling signal is obtained using a measurement current transformer, Fourier transform and singularity detection are performed, the time scale of the mutation point is determined, and the protection current sampling point is replaced based on the measurement current sampling point, and calibration is performed.
Effectively utilize the high sampling accuracy of measuring current, compensate for the low-value sampling accuracy of protection current, reduce the number of optional AC modules of relay protection terminals, and improve the ability to take into account both sampling accuracy and range.
Smart Images
Figure CN119716705A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of power system protection and control, and in particular to a method, system, device and medium for calibrating protection current based on measured current. Background Art
[0002] Current transformer (CT) is an important component to ensure the safe and stable operation of the power system. At present, the AC modules of relay protection terminals in engineering generally adopt two options of 1A and 5A for protection CT rated current. Exceptionally, for transformers, reactors, motors, etc. with two or even three sides, if the parameters of the transformers on each side are inconsistent, an AC module will have 4 or even 9 options. The sampling accuracy of the AC module with a protection CT rated current of 5A is not as good as that of the AC module with a 1A under low value conditions; on the contrary, the sampling range of the AC module with a protection CT rated current of 1A is far worse than that of the AC module with a 5A. Therefore, while reducing the selection of AC modules, the problem of not losing the sampling range of the AC module and ensuring the sampling accuracy needs to be solved urgently. In summary, there is still a technical problem that the sampling accuracy and sampling range cannot coexist for power grid protection. Summary of the invention
[0003] The purpose of the present invention is to provide a method, system, device and medium for calibrating protection current based on measured current in order to solve at least one of the above technical problems.
[0004] In the first aspect, an embodiment of the present invention provides a method for calibrating a protection current based on a measured current, which is applied to a relay protection terminal of a target power system; the relay protection terminal includes a protection current transformer and a measuring current transformer; the method includes: based on the protection current transformer and the measuring current transformer, respectively obtaining a three-phase protection current sampling signal and a three-phase measurement current sampling signal of the target power system; performing Fourier transform on the three-phase protection current sampling signal to obtain a fundamental frequency domain signal; performing singularity detection on the fundamental frequency domain signal to determine a mutation point time mark of the fundamental frequency domain signal; in the three-phase protection current sampling signal and the three-phase measurement current sampling signal, respectively determining the three-phase protection current sampling point and the three-phase measurement current sampling point corresponding to the mutation point time mark; calibrating the three-phase protection current sampling point based on the three-phase measurement current sampling point to obtain the calibrated three-phase protection current sampling signal.
[0005] Furthermore, the fundamental frequency domain signal includes a sinusoidal signal of a fundamental wave; singularity detection is performed on the fundamental frequency domain signal to determine a mutation point time stamp of the fundamental frequency domain signal, including: taking a first-order derivative of the sinusoidal signal of the fundamental wave to obtain a change signal; and determining a sampling time point corresponding to an uneven point or discontinuity point of the change signal as the mutation point time stamp.
[0006] Further, calibrating the three-phase protection current sampling points based on the three-phase measurement current sampling points includes: replacing the three-phase protection current sampling points with the three-phase measurement current sampling points.
[0007] Furthermore, the three-phase protection current sampling points are replaced by the three-phase measurement current sampling points, including: based on the transformation ratio of the measurement current transformer, converting the three-phase measurement current sampling points into primary current values of the power system; based on the transformation ratio of the protection current transformer, converting the primary current value into replacement sampling points, and replacing the three-phase protection current sampling points with the replacement sampling points.
[0008] Furthermore, the acquisition time of the three-phase protection current sampling signal and the three-phase measurement current sampling signal is the same.
[0009] Furthermore, the method also includes: extracting the protection current primary signal corresponding to the three-phase protection current sampling signal within the target time window; the protection current primary signal includes the protection current primary value amplitude and the protection current primary value phase; the target time window is an abnormality detection window; extracting the measurement current primary signal corresponding to the three-phase measurement current sampling signal within the target time window; the measurement current primary signal includes the measurement current primary value amplitude and the measurement current primary value phase; based on the difference between the protection current primary signal and the measurement current primary signal, determining whether there is a sampling abnormality in the relay protection terminal.
[0010] In a second aspect, an embodiment of the present invention further provides a system for calibrating protection current based on measurement current, which is applied to a relay protection terminal of a target power system; the relay protection terminal includes a protection current transformer and a measurement current transformer; the system includes: an acquisition module, a transformation module, a detection module, a determination module and a calibration module; wherein the acquisition module is used to respectively acquire a three-phase protection current sampling signal and a three-phase measurement current sampling signal of the target power system based on the protection current transformer and the measurement current transformer; the transformation module is used to perform Fourier transform on the three-phase protection current sampling signal to obtain a fundamental frequency domain signal; the detection module is used to perform singularity detection on the fundamental frequency domain signal to determine the mutation point time mark of the fundamental frequency domain signal; the determination module is used to respectively determine the three-phase protection current sampling point and the three-phase measurement current sampling point corresponding to the mutation point time mark in the three-phase protection current sampling signal and the three-phase measurement current sampling signal; the calibration module is used to calibrate the three-phase protection current sampling point based on the three-phase measurement current sampling point to obtain the calibrated three-phase protection current sampling signal.
[0011] Furthermore, it also includes an abnormality detection module, which is used to: extract the protection current primary signal corresponding to the three-phase protection current sampling signal within the target time window; the protection current primary signal includes the protection current primary value amplitude and the protection current primary value phase; the target time window is an abnormality detection window; extract the measurement current primary signal corresponding to the three-phase measurement current sampling signal within the target time window; the measurement current primary signal includes the measurement current primary value amplitude and the measurement current primary value phase; based on the difference between the protection current primary signal and the measurement current primary signal, determine whether there is a sampling abnormality in the relay protection terminal.
[0012] In a third aspect, an embodiment of the present invention further provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method provided in the embodiment of the present invention when executing the computer program.
[0013] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and when the computer instructions are executed by a processor, the method provided in the embodiment of the present invention is implemented.
[0014] The present invention provides a method, system, device and medium for calibrating protection current based on measured current, which effectively utilizes the high sampling accuracy of measured current, compensates for the sampling accuracy of low value of protection current, has low design cost and high reliability, and alleviates the problem of too many optional AC modules of relay protection terminals in existing projects, as well as the technical problem of incompatibility between AC module sampling accuracy and sampling range in existing power grid protection. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0016] Figure 1 A flow chart of a method for calibrating a protection current based on a measured current provided by an embodiment of the present invention;
[0017] Figure 2 A wiring diagram of a relay protection terminal provided in an embodiment of the present invention;
[0018] Figure 3 A flow chart of a sampling abnormality diagnosis method for a relay protection terminal provided by an embodiment of the present invention;
[0019] Figure 4 A schematic diagram of a system for calibrating protection current based on measured current provided by an embodiment of the present invention.
[0020] In the figure: 1. Relay protection terminal, 2. Protection current transformer, 3. Measuring current transformer. DETAILED DESCRIPTION
[0021] 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 only 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 are within the scope of protection of the present invention.
[0022] Embodiment 1
[0023] Figure 1 The present invention provides a flowchart of a method for calibrating a protection current based on a measured current, which is applied to a relay protection terminal of a target power system. Figure 2 FIG. 1 is a wiring diagram of a relay protection terminal provided according to an embodiment of the present invention. Figure 2As shown, the relay protection terminal 1 includes a protection current transformer 2 and a measuring current transformer 3, and the protection current transformer 2 and the measuring current transformer 3 respectively transmit the protection current and the measuring current to the relay protection terminal 1.
[0024] In an optional implementation provided by an embodiment of the present invention, the rated current of the protection current transformer 2 is 5 A, and the rated current of the measuring current transformer 3 is 5 A. When the protection action setting value of the relay protection terminal is set to a preset low value range, such as 0-0.2 A, the relay protection terminal starts the method for calibrating the protection current based on the measuring current provided by an embodiment of the present invention.
[0025] like Figure 1 As shown, the method provided in the embodiment of the present invention specifically includes the following steps:
[0026] Step S102: based on the protection current transformer and the measurement current transformer, respectively obtain a three-phase protection current sampling signal and a three-phase measurement current sampling signal of the target power system.
[0027] Specifically, the acquisition time of the three-phase protection current sampling signal and the three-phase measurement current sampling signal is the same.
[0028] Specifically, Figure 2 As shown, the relay protection terminal 1 simultaneously collects multiple three-phase protection current sampling points of the protection current transformer 2 in the form of sampling points to obtain three-phase protection current sampling signals and multiple three-phase measurement current sampling points of the measurement current transformer 3 to obtain three-phase measurement current sampling signals. Among them, the sampling signal includes the amplitude, phase and time scale of the sampling point.
[0029] Step S104, perform Fourier transform on the three-phase protection current sampling signal to obtain a fundamental frequency domain signal. Optionally, the fundamental frequency domain signal includes a fundamental sinusoidal signal.
[0030] Step S106, performing singularity detection on the fundamental frequency domain signal to determine the time scale of the mutation point of the fundamental frequency domain signal. Specifically, the process includes the following steps:
[0031] Step S1061, taking a first-order derivative of the fundamental wave sinusoidal signal to obtain a change signal;
[0032] Step S1062: determine the sampling time point corresponding to the uneven point or discontinuity point of the change signal as the mutation point time mark.
[0033] Specifically, the mutation point of the fundamental frequency domain signal appears in the result of the first-order derivative in the form of an uneven point or a discontinuity point.
[0034] Step S108, respectively determining the three-phase protection current sampling point and the three-phase measurement current sampling point corresponding to the mutation point time stamp in the three-phase protection current sampling signal and the three-phase measurement current sampling signal.
[0035] Step S110, calibrating the three-phase protection current sampling points based on the three-phase measurement current sampling points to obtain calibrated three-phase protection current sampling signals.
[0036] Preferably, the calibration process includes: replacing the three-phase protection current sampling points with the three-phase measurement current sampling points. Specifically, it includes the following steps:
[0037] Step S1101, based on the transformation ratio of the measuring current transformer, convert the three-phase measuring current sampling points into the primary current value of the power system;
[0038] Step S1102: based on the transformation ratio of the protection current transformer, convert the primary current value into a replacement sampling point, and use the replacement sampling point to replace the three-phase protection current sampling point.
[0039] Specifically, after the mutation point time mark is obtained, the corresponding three-phase measurement current sampling point is found using the mutation point time mark, and the mutation point of the three-phase current sampling point is replaced by the value of the sampling point to form a new protection current, and finally the calibrated three-phase protection current sampling signal is used to perform protection logic calculation.
[0040] In an embodiment of the present invention, the three-phase protection current sampling signal and the three-phase measurement current sampling signal obtained by the relay protection terminal are both secondary values. The number of sampling points of the three-phase protection current sampling signal and the three-phase measurement current sampling signal in the same time window may be inconsistent, but the amplitude and phase difference of the primary value of the sampling point corresponding to the same time mark are within a preset range. Based on this, the method provided in the embodiment of the present invention also includes diagnosing the sampling anomaly of the relay protection terminal.
[0041] Figure 3 FIG. 1 is a flow chart of a sampling abnormality diagnosis method for a relay protection terminal according to an embodiment of the present invention. Figure 3 As shown, the method comprises the following steps:
[0042] Step S302, extracting the protection current primary signal corresponding to the three-phase protection current sampling signal within the target time window; the protection current primary signal includes the protection current primary value amplitude and the protection current primary value phase; the target time window is an abnormality detection window, for example, 0.06s.
[0043] Step S304, extracting the measured current primary signal corresponding to the three-phase measured current sampling signal within the target time window; the measured current primary signal includes the measured current primary value amplitude and the measured current primary value phase.
[0044] Step S306: Determine whether there is sampling abnormality in the relay protection terminal based on the difference between the protection current primary signal and the measurement current primary signal.
[0045] For example, based on the measured current, the amplitude error of the sampling points corresponding to the same time scale does not exceed 2%, and the phase difference does not exceed ±2%. If any error of the phase comparison and amplitude comparison of all the primary value sampling points in the target time window does not meet the above conditions, it is determined that there is a sampling abnormality in the relay protection terminal and an alarm signal is issued.
[0046] The present invention provides a method for calibrating protection current based on measured current, which effectively utilizes the high sampling accuracy of measured current to compensate for the sampling accuracy of low value of protection current. It has low design cost and high reliability, and alleviates the problem of too many optional AC modules of relay protection terminals in existing projects, as well as the technical problem of incoexistence of AC module sampling accuracy and sampling range in existing power grid protection.
[0047] Embodiment 2
[0048] Figure 4 1 is a schematic diagram of a system for calibrating protection current based on measurement current according to an embodiment of the present invention, the system is applied to a relay protection terminal of a target power system; the relay protection terminal includes a protection current transformer and a measurement current transformer. Figure 4 As shown, the system includes: an acquisition module 10, a transformation module 20, a detection module 30, a determination module 40 and a calibration module 50.
[0049] Specifically, the acquisition module 10 is used to respectively acquire a three-phase protection current sampling signal and a three-phase measurement current sampling signal of the target power system based on the protection current transformer and the measurement current transformer;
[0050] The transformation module 20 is used to perform Fourier transformation on the three-phase protection current sampling signal to obtain a fundamental frequency domain signal;
[0051] The detection module 30 is used to perform singularity detection on the fundamental frequency domain signal and determine the time mark of the mutation point of the fundamental frequency domain signal;
[0052] A determination module 40, for respectively determining the three-phase protection current sampling point and the three-phase measurement current sampling point corresponding to the mutation point time stamp in the three-phase protection current sampling signal and the three-phase measurement current sampling signal;
[0053] The calibration module 50 is used to calibrate the three-phase protection current sampling points based on the three-phase measurement current sampling points to obtain the calibrated three-phase protection current sampling signals.
[0054] Specifically, the fundamental frequency domain signal includes a sinusoidal signal of the fundamental wave; the determination module 40 is also used to: perform a first-order derivative of the sinusoidal signal of the fundamental wave to obtain a change signal; and determine the sampling time point corresponding to the uneven point or discontinuity point of the change signal as the mutation point time mark.
[0055] Specifically, the calibration module 50 is further configured to replace the three-phase protection current sampling points with the three-phase measurement current sampling points.
[0056] like Figure 4 As shown, the system provided by the embodiment of the present invention further includes an abnormality detection module 60, which is used to:
[0057] Extract the protection current primary signal corresponding to the three-phase protection current sampling signal within the target time window; the protection current primary signal includes the protection current primary value amplitude and the protection current primary value phase; the target time window is the abnormality detection window;
[0058] Extracting the measured current primary signal corresponding to the three-phase measured current sampling signal within the target time window; the measured current primary signal includes the measured current primary value amplitude and the measured current primary value phase;
[0059] Based on the difference between the protection current primary signal and the measurement current primary signal, determine whether there is sampling abnormality in the relay protection terminal.
[0060] The present invention further provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method provided in the embodiment of the present invention when executing the computer program.
[0061] The present invention also provides a computer-readable storage medium, which stores computer instructions. When the computer instructions are executed by a processor, the method provided in the embodiment of the present invention is implemented.
[0062] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.
[0063] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.
Claims
1. A method for calibrating a protection current based on a measured current, characterized in that: Relay protection terminals applied to target power systems; The relay protection terminal includes a protection current transformer and a measurement current transformer; the method includes: Based on the protection current transformer and the measurement current transformer, respectively obtaining a three-phase protection current sampling signal and a three-phase measurement current sampling signal of the target power system; Performing Fourier transform on the three-phase protection current sampling signal to obtain a fundamental frequency domain signal; Performing singularity detection on the fundamental frequency domain signal to determine the time scale of the mutation point of the fundamental frequency domain signal; In the three-phase protection current sampling signal and the three-phase measurement current sampling signal, respectively determine the three-phase protection current sampling point and the three-phase measurement current sampling point corresponding to the mutation point time stamp; The three-phase protection current sampling points are calibrated based on the three-phase measurement current sampling points to obtain calibrated three-phase protection current sampling signals.
2. The method according to claim 1, characterized in that: The fundamental frequency domain signal includes a fundamental sinusoidal signal; performing singularity detection on the fundamental frequency domain signal to determine a time scale of a mutation point of the fundamental frequency domain signal includes: Taking a first-order derivative of the fundamental wave sinusoidal signal to obtain a change signal; The sampling time point corresponding to the non-smooth point or discontinuous point of the change signal is determined as the mutation point time mark.
3. The method according to claim 1, characterized in that: Calibrating the three-phase protection current sampling points based on the three-phase measurement current sampling points includes: replacing the three-phase protection current sampling points with the three-phase measurement current sampling points.
4. The method according to claim 3, characterized in that: Replacing the three-phase protection current sampling point with the three-phase measurement current sampling point comprises: Based on the transformation ratio of the measuring current transformer, converting the three-phase measuring current sampling points into primary current values of the power system; Based on the transformation ratio of the protection current transformer, the primary current value is converted into a replacement sampling point, and the three-phase protection current sampling point is replaced by the replacement sampling point.
5. The method according to claim 1, characterized in that: The acquisition time of the three-phase protection current sampling signal and the three-phase measurement current sampling signal is the same.
6. The method according to claim 1, characterized in that: The method further comprises: Extracting the protection current primary signal corresponding to the three-phase protection current sampling signal within the target time window; the protection current primary signal includes the protection current primary value amplitude and the protection current primary value phase; the target time window is an abnormality detection window; Extracting the measured current primary signal corresponding to the three-phase measured current sampling signal within the target time window; the measured current primary signal includes the measured current primary value amplitude and the measured current primary value phase; Based on the difference between the protection current primary signal and the measurement current primary signal, it is determined whether there is a sampling abnormality in the relay protection terminal.
7. A system for calibrating protection current based on measured current, characterized in that: A relay protection terminal applied to a target power system; the relay protection terminal includes a protection current transformer and a measurement current transformer; the system includes: an acquisition module, a transformation module, a detection module, a determination module and a calibration module; wherein, The acquisition module is used to respectively acquire a three-phase protection current sampling signal and a three-phase measurement current sampling signal of the target power system based on the protection current transformer and the measurement current transformer; The transformation module is used to perform Fourier transformation on the three-phase protection current sampling signal to obtain a fundamental frequency domain signal; The detection module is used to perform singularity detection on the fundamental frequency domain signal to determine the time scale of the mutation point of the fundamental frequency domain signal; The determination module is used to respectively determine the three-phase protection current sampling point and the three-phase measurement current sampling point corresponding to the mutation point time stamp in the three-phase protection current sampling signal and the three-phase measurement current sampling signal; The calibration module is used to calibrate the three-phase protection current sampling points based on the three-phase measurement current sampling points to obtain calibrated three-phase protection current sampling signals.
8. The system according to claim 7, characterized in that: Also included is an anomaly detection module for: Extracting the protection current primary signal corresponding to the three-phase protection current sampling signal within the target time window; the protection current primary signal includes the protection current primary value amplitude and the protection current primary value phase; The target time window is an anomaly detection window; Extracting the measured current primary signal corresponding to the three-phase measured current sampling signal within the target time window; the measured current primary signal includes the measured current primary value amplitude and the measured current primary value phase; Based on the difference between the protection current primary signal and the measurement current primary signal, it is determined whether there is a sampling abnormality in the relay protection terminal.
9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method according to any one of claims 1 to 6 when executing the computer program.
10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and when the computer instructions are executed by a processor, the method according to any one of claims 1 to 6 is implemented.