Method and system for eliminating misoperation caused by large number

Abstract

The application provides a method and system for eliminating misoperation caused by a large number, which comprises the following steps: obtaining a new sampling value in each sampling interruption, calculating by using a recursive algorithm to obtain a recursive result of a current sampling point; triggering a care task, performing non-recursive calculation on the current sampling point corresponding to the triggering of the care task to obtain a non-recursive result of the current sampling point; comparing the recursive result and the non-recursive result, if the same, ending the care task, waiting for the triggering of the care task again to perform the next round of verification, if different, locking the protection function and clearing the data of the sampling related cache area, and then performing the next round of verification. The method combining the cyclic verification with the protection start trigger verification can accurately and timely identify the cumulative abnormality and the sampling abnormality, effectively solves the calculation precision problem and the misoperation problem caused by the cumulative error and the abnormal sampling, guarantees the safety and reliability of the operation of the relay protection device, and has good engineering practical value.

Description

Technical Field

[0001] This invention relates to the field of power systems and their automation technology, and more specifically, to a method and system for eliminating malfunctions caused by large numbers. Background Technology

[0002] Relay protection devices need to calculate the effective value and phase of the acquired electrical quantities from discrete A / D sampled data. The Fourier algorithm, due to its excellent ability to filter out integer harmonics and extract fundamental components, is widely used in microprocessor-based relay protection. In practical relay protection devices, the Fourier algorithm is applied in two ways: recursive and non-recursive. The recursive algorithm has a smaller computational load, while the non-recursive Fourier algorithm has a larger computational load. Especially for bus protection, station protection, and other protection systems with many analog input channels, the non-recursive algorithm may overload the CPU, causing fault task execution timeouts and preventing the completion of all analog calculations and protection logic within a single fault task cycle, thus compromising response speed. While the less computationally intensive half-cycle Fourier algorithm can be used, it cannot achieve ideal filtering effects, resulting in decreased protection accuracy and compromised calculation precision. To balance computational accuracy and computational load, the recursive Fourier algorithm has been widely adopted.

[0003] The recursive Fourier algorithm, based on the discrete Fourier transform, uses known conditions (the results of historical sampling points that have already been calculated) and a specific calculation formula to derive the calculation result of the current sampling point.

[0004] However, the recursive Fourier algorithm is affected by accumulated errors and outlier sampling points. From the perspective of digital filters, the recursive algorithm and the infinite impulse response digital filter share the same principle: the output at the current moment depends not only on the input at the current moment but also on the output from an infinitely long time ago. Therefore, during historical calculations, quantization errors from A / D conversion, errors caused by the finite word length effect of the CPU, quantization errors of filter coefficients, fixed-point operation errors of the digital filter, truncation errors generated during numerical computation, and errors caused by spectral leakage from the Fourier algorithm, etc., will accumulate throughout the recursive process, forming accumulated errors that cannot be eliminated and will continuously affect the calculation results. In addition, when sampling points are abnormal due to electromagnetic interference or hardware malfunctions, the errors caused by the abnormal sampling data will also be retained in subsequent recursive calculation results and cannot be automatically eliminated.

[0005] To address the issues of accumulated error and susceptibility to abnormal sampling points in the recursive Fourier algorithm, existing methods have made various improvements. However, various problems still exist, including a high dependence on CPU and storage resources, resulting in a considerable computational workload; inability to handle sudden increases in accumulated error, leading to a large computational burden.

[0006] Existing patent 1 proposes a synchronous phasor calculation method based on FPGA hardware DFT recursion (CN102902879B), which proposes a method to correct recursive calculation errors by using a second pulse timer and a non-recursive algorithm. However, the method proposed in this existing patent has the problem of excessively long correction period, which cannot quickly eliminate the impact of accumulated errors. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for eliminating false tripping caused by large numbers. This method can solve the problems of calculation accuracy and false tripping caused by accumulated errors and abnormal sampling, thus ensuring the safety and reliability of relay protection device operation.

[0008] The present invention adopts the following technical solution.

[0009] A method for eliminating false triggers caused by large numbers includes the following steps:

[0010] Step 1: For each sampling interruption, a new sample value is obtained. The recursive algorithm is used to calculate the recursive result of the current sampling point.

[0011] Step 2: Trigger the care task, perform non-recursive calculation on the current sampling point corresponding to the triggering of the care task, and obtain the non-recursive result of the current sampling point;

[0012] Step 3: Compare the recursive result and the non-recursive result. If they are the same, end the current care task and wait for the care task to be triggered again for the next round of verification. If they are different, lock the protection function and clear the data in the sampling-related buffer area before proceeding to the next round of verification.

[0013] Preferably, in step 1, a step-by-step calculation method is adopted, and the recursion is performed only once in each sampling interruption to calculate the recursion result of the current sampling point.

[0014] Preferably, in step 1, if the data window length is N, then N points are sampled per power frequency cycle, and only one recursion is performed in each sampling interruption to calculate the second real part R2 and the second imaginary part I2 of the collected electrical quantity, resulting in a total of N second real parts R2 and second imaginary parts I2.

[0015] Preferably, in step 2, the triggering method for the care task further includes: periodic triggering and relay protection device protection start triggering.

[0016] Preferably, step 2 further includes:

[0017] Step 2.1: Create a caregiving task using the recursive Fourier algorithm, and use a non-recursive Fourier algorithm to perform cyclical verification at a set scheduling period;

[0018] Step 2.2: Perform non-recursive calculation on the current sampling point corresponding to the triggering of the care task to obtain the non-recursive result, including the first real part R1 and the first imaginary part I1 of the collected electrical quantity.

[0019] Preferably, step 3 further includes:

[0020] Step 3.1: Compare the recursive result obtained in Step 1 with the non-recursive result obtained in Step 2;

[0021] Step 3.2: If the recursive result and the non-recursive result are equal, the current caregiving task ends and waits for the caregiving task to be triggered again for the next round of verification.

[0022] Step 3.3: If the recursive result and the non-recursive result are not equal, the protection function is locked and the data in the sampling-related buffer is cleared, and then the next round of verification is performed.

[0023] Preferably, in step 3.1, the recursive result of the sampling point in step 1 is selected for comparison based on the non-recursive result of the sampling point calculated in step 2.

[0024] Preferably, the comparison between the recursive result and the non-recursive result in step 3 further includes: comparing the second real part R2 of the recursive result with the first real part R1 of the non-recursive result, and comparing the second imaginary part I2 of the recursive result with the first imaginary part I1 of the non-recursive result. If they are all equal, it means that the recursive result and the non-recursive result are equal; otherwise, it means that the recursive result and the non-recursive result are not equal.

[0025] Preferably, step 3.3 further includes:

[0026] Step 3.3.1: If the results obtained by the two algorithms are different, then immediately disable system task scheduling;

[0027] Step 3.3.2: Disable all CPU interrupts, including sampling interrupts;

[0028] Step 3.3.3: Clear all data such as the A / D sampling buffer, sampling counter, and recursive results of the relay protection device connected to the voltage and current.

[0029] Step 3.3.4: Re-enable CPU interrupts and restore the sampling interrupt function;

[0030] Step 3.3.5: Delay and wait for the A / D sampling buffer to accumulate N points of sampled data to meet the requirement of a data window length;

[0031] Step 3.3.6: End the current guarding task and enable the system task scheduling function.

[0032] The present invention also provides a system for eliminating false alarms caused by large numbers, comprising: a task triggering module, a recursive calculation module, a non-recursive calculation module, and a processing module;

[0033] The task triggering module is used to control the triggering of caregiving tasks and enable verification.

[0034] The recursive calculation module can use the recursive algorithm to calculate and obtain the recursive result of the sampling point;

[0035] The non-recursive calculation module can use a non-recursive algorithm to perform calculations and obtain non-recursive results for the sampling points.

[0036] The processing module can compare the recursive and non-recursive results of the sampling points, and process them according to whether the comparison results are equal, thus completing one round of verification.

[0037] The beneficial effects of this invention are that, compared with the prior art, it proposes an improved recursive Fourier algorithm method to eliminate maloperation caused by large numbers. This method combines cyclic verification with protection start-up trigger verification, enabling accurate and timely identification of accumulated anomalies and sampling anomalies. It effectively solves the calculation accuracy problems and maloperation problems caused by accumulated errors and abnormal sampling, ensuring the safety and reliability of relay protection device operation. This method successfully eliminates the limitations of the recursive Fourier algorithm and has good practical engineering value. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the overall process of a method for eliminating false alarms caused by large numbers provided by the present invention;

[0039] Figure 2 This is a schematic diagram illustrating the specific implementation steps of a method for eliminating false alarms caused by large numbers provided by the present invention;

[0040] Figure 3 This is a schematic diagram of the structure of a system for eliminating malfunctions caused by large numbers, provided by the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, other embodiments obtained by those skilled in the art without creative effort are all within the protection scope of this invention.

[0042] like Figure 1 , 2 As shown, this embodiment of the invention provides a method for eliminating false alarms caused by large numbers, comprising the following steps:

[0043] Step 1: For each sampling interruption, a new sample value is obtained. The recursive Fourier algorithm is used to calculate the recursive result of the current sampling point.

[0044] In a preferred but non-limiting embodiment of the present invention, in step 1, a new sample value is obtained for each sampling interruption, and a recursive Fourier algorithm is used to perform a calculation to obtain the recursive result of the current sampling point. More specifically, a step-by-step calculation method is adopted, and the recursion is performed only once in each sampling interruption to calculate the recursive result of the current sampling point, thereby obtaining the second real part R2 and the second imaginary part I2 of the collected electrical quantity.

[0045] As a non-restrictive example, let N represent the data window length. N points are sampled per power frequency cycle. If N = 32, meaning the data window length is 32, 32 points are sampled per power frequency cycle. A sampling interruption occurs every 625µs, meaning a recursive calculation is performed every 625µs to obtain the recursive result. Each power frequency cycle yields 32 real parts R² and imaginary parts I².

[0046] Step 2: Trigger the care task, perform non-recursive calculation on the current sampling point corresponding to the triggering of the care task, and obtain the non-recursive result of the current sampling point.

[0047] Specifically, step 2 also includes:

[0048] Step 2.1: Create a caregiving task using the recursive Fourier algorithm, and use a non-recursive Fourier algorithm to perform cyclical verification at a set scheduling period;

[0049] In a preferred but non-limiting embodiment of the present invention, the methods for triggering the care task include: periodic triggering and relay protection device protection start-up triggering.

[0050] In a further preferred but non-limiting embodiment, the period for periodically triggering the caregiving task is 1 second.

[0051] It is worth noting that in this invention, the term "task" is a concept from an operating system, and the entire Fourier algorithm is loaded and runs within the caregiving task. In the operating system, tasks can be continuously scheduled for execution; therefore, each execution of the caregiving task is equivalent to one round of verification. Running the caregiving task 100 times is equivalent to 100 rounds of verification, and so on. For example, but not limited to, setting the caregiving task to execute once per second means that one round of verification occurs every 1 second.

[0052] Furthermore, in addition to setting a scheduling cycle to trigger the care task cycle, the relay protection device in this invention immediately triggers a verification cycle after determining that the protection has been activated, that is, the care task is triggered by the activation of the protection through the relay protection device.

[0053] Step 2.2: Perform non-recursive calculation on the current sampling point corresponding to the triggering of the care task to obtain the non-recursive result, including the first real part R1 and the first imaginary part I1 of the collected electrical quantity.

[0054] Specifically, in step 1, recursive calculations are required for each sampling point. However, the monitoring algorithm does not perform non-recursive calculations for every sampling point. Instead, whenever the monitoring task begins its current round of verification, it takes the current sampling point corresponding to the triggering of the monitoring task and performs a non-recursive calculation using the non-recursive Fourier algorithm to obtain a non-recursive result. This result is then compared with the recursive result corresponding to that sampling point in step 1. The obtained non-recursive result includes the first real part R1 and the first imaginary part I1 of the collected electrical quantity.

[0055] Based on the example in step 1, when the data window length is 32, there are 32 sampling points. When performing non-recursive calculation, the current sampling point corresponding to the triggering of the care algorithm and the 31 sampling points previously sampled are taken and a non-recursive calculation is performed to obtain the recursive result of the current sampling point corresponding to the triggering of the care algorithm.

[0056] Step 3: Compare the recursive result and the non-recursive result. If they are the same, end the current care task and wait for the care task to be triggered again for the next round of verification. If they are different, lock the protection function and clear the data in the sampling-related buffer area before proceeding to the next round of verification.

[0057] Specifically, step 3 also includes:

[0058] Step 3.1 involves comparing the recursive and non-recursive results.

[0059] In this process, the recursive results obtained in step 1 are labeled. Since the care task in step 2 is triggered slowly, when a certain round of care task starts to perform this round of verification, a non-recursive calculation is performed on a certain sampling point that has been collected in step 1 to obtain the non-recursive result corresponding to that sampling point. Then, the recursive result and non-recursive result of that sampling point are compared.

[0060] For example, when there are 32 sampling points, the recursive results of these 32 sampling points are numbered 1-32. If the current round of caregiving tasks begins at the 18th sampling point, then the non-recursive result for sampling point 18 will be calculated. Therefore, the recursive result and the non-recursive result for sampling point 18 will be compared. That is, step 1 yields the recursive results of 32 sampling points, but step 3 will only sample a portion of these 32 sampling points.

[0061] Step 3.2: If the recursive result and the non-recursive result are equal, the current caregiving task ends, and the task waits for the caregiving task to be triggered again for the next round of verification.

[0062] Specifically, the comparison between the recursive result and the non-recursive result also includes: comparing the second real part R2 of the recursive result with the first real part R1 of the non-recursive result, and comparing the second imaginary part I2 of the recursive result with the first imaginary part I1 of the non-recursive result. If they are all equal, it means that the recursive result and the non-recursive result are equal; otherwise, it means that the recursive result and the non-recursive result are not equal.

[0063] Step 3.3: If they are not equal, the protection function is locked and the data in the sampling-related buffer is cleared, and then the next round of verification is performed.

[0064] To ensure the reliable operation of the protection device, a data window's worth of data must be accumulated before the current monitoring task can be completed and the system can wait for the next round of verification. Specifically, step 3.3 also includes:

[0065] Step 3.3.1: If the results obtained by the two algorithms are different, then system task scheduling should be immediately disabled.

[0066] Step 3.3.2: Disable all CPU interrupts, including sampling interrupts.

[0067] Step 3.3.3: Clear all data such as the A / D sampling buffer, sampling counter, and recursive results of the relay protection device connected to the voltage and current.

[0068] In this invention, the function of clearing data includes: if there is error accumulation or abnormal sampling data in the current sampling buffer, a data window is resampled and the recursive result is recalculated to eliminate error accumulation and abnormality, and then used for the protection function of fault tasks.

[0069] Step 3.3.4: Re-enable CPU interrupts and restore sampling interrupt function.

[0070] Step 3.3.5: Delay and wait for the A / D sampling buffer to accumulate N points of sampled data to meet the requirement of a data window length.

[0071] Step 3.3.6: End the current guarding task and enable the system task scheduling function.

[0072] Specifically, the faulty task scheduling is restored, and the task is quickly switched back from the Fu family care task to continue running.

[0073] like Figure 3 As shown, another embodiment of the present invention also proposes a system for eliminating false triggering caused by large numbers, so that the method for eliminating false triggering caused by large numbers proposed in the previous embodiment can be implemented based on the system. Specifically, the system includes: a task triggering module, a recursive calculation module, a non-recursive calculation module, and a processing module.

[0074] The task triggering module is used to control the triggering of caregiving tasks and enable verification.

[0075] The recursive calculation module can use the recursive Fourier algorithm to calculate and obtain the recursive results of the sampling points;

[0076] The non-recursive calculation module can use the non-recursive Fourier algorithm to perform calculations and obtain non-recursive results for the sampling points.

[0077] The processing module can compare the recursive and non-recursive results of the sampling points, and process them according to whether the comparison results are equal, thus completing one round of verification.

[0078] The beneficial effects of this invention are that, compared with the prior art, it employs a method combining cyclic verification and protection start-up trigger verification, which can accurately and promptly identify accumulated anomalies and sampling anomalies. This effectively solves the calculation accuracy problems and malfunction problems caused by accumulated errors and abnormal sampling, ensuring the safety and reliability of the relay protection device. This method successfully eliminates the limitations of the recursive Fourier algorithm and has good practical engineering value.

[0079] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0080] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0081] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0082] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for eliminating false alarms caused by large numbers, characterized in that, Includes the following steps: Step 1: For each sampling interruption, a new sample value is obtained. The recursive algorithm is used to calculate the recursive result of the current sampling point. Step 2: Trigger the care task, perform non-recursive calculation on the current sampling point corresponding to the triggering of the care task, and obtain the non-recursive result of the current sampling point; In step 2, the triggering method for the care task includes: relay protection device protection start triggering; Step 3 includes: Step 3.1: Compare the recursive result obtained in Step 1 with the non-recursive result obtained in Step 2; Step 3.2: If the recursive result and the non-recursive result are equal, the current caregiving task ends and waits for the caregiving task to be triggered again for the next round of verification. Step 3.3: If the recursive result and the non-recursive result are not equal, the protection function is locked and the data in the sampling-related buffer is cleared, and then the next round of verification is performed; The aforementioned lockout protection function and clearing the data in the sampling-related buffer specifically include: Step 3.3.1: If the results obtained by the two algorithms are different, then immediately disable system task scheduling; Step 3.3.2: Disable all CPU interrupts, including sampling interrupts; Step 3.3.3: Clear all A / D sampling buffers, sampling counters, and recursive result data of the relay protection device connected to the voltage and current. Step 3.3.4: Re-enable CPU interrupts and restore the sampling interrupt function; Step 3.3.5: Delay and wait for the A / D sampling buffer to accumulate N points of sampled data to meet the requirement of a data window length; Step 3.3.6: End the current guarding task and enable the system task scheduling function.

2. The method for eliminating false alarms caused by large numbers according to claim 1, characterized in that, In step 1, a step-by-step calculation method is adopted, and the recursion is performed only once in each sampling interruption to calculate the recursion result of the current sampling point.

3. The method for eliminating false alarms caused by large numbers according to claim 2, characterized in that, In step 1, if the data window length is N, then N points are sampled per power frequency cycle. Only one recursion is performed in each sampling interruption to calculate the second real part R2 and the second imaginary part I2 of the collected electrical quantity, resulting in a total of N second real parts R2 and second imaginary parts I2.

4. The method for eliminating false alarms caused by large numbers according to claim 1, characterized in that, In step 2, the triggering method for the care task also includes: periodic triggering.

5. The method for eliminating false alarms caused by large numbers according to claim 3, characterized in that, Step 2 also includes: Step 2.1: Create a caregiving task using the recursive Fourier algorithm, and use a non-recursive Fourier algorithm to perform cyclical verification at a set scheduling period; Step 2.2: Perform non-recursive calculation on the current sampling point corresponding to the triggering of the care task to obtain the non-recursive result, including the first real part R1 and the first imaginary part I1 of the collected electrical quantity.

6. The method for eliminating false alarms caused by large numbers according to claim 1, characterized in that, In step 3.1, the non-recursive result of the sampling point calculated in step 2 is used to select the recursive result of the sampling point in step 1 for comparison.

7. The method for eliminating false alarms caused by large numbers according to claim 6, characterized in that, The comparison between the recursive result and the non-recursive result in step 3 further includes: comparing the second real part R2 of the recursive result with the first real part R1 of the non-recursive result, and comparing the second imaginary part I2 of the recursive result with the first imaginary part I1 of the non-recursive result. If they are all equal, it means that the recursive result and the non-recursive result are equal; otherwise, it means that the recursive result and the non-recursive result are not equal.

8. A system for eliminating malfunctions caused by large numbers, implementing the method for eliminating malfunctions caused by large numbers as described in any one of claims 1 to 7, characterized in that, include: The module consists of a task triggering module, a recursive calculation module, a non-recursive calculation module, and a processing module. The task triggering module is used to control the triggering of caregiving tasks and enable verification. The recursive calculation module can use the recursive algorithm to calculate and obtain the recursive result of the sampling point; The non-recursive calculation module can use a non-recursive algorithm to perform calculations and obtain non-recursive results for the sampling points. The processing module can compare the recursive and non-recursive results of the sampling points, and process them according to whether the comparison results are equal, thus completing one round of verification.

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