A method and system for evaluating the sampling consistency of multi-channel ADCs in a relay protection device

Abstract

The present invention discloses a method and system for evaluating the sampling consistency of multiple channels of a relay protection device, which enables each channel to be tested to be under the excitation of the same external AC analog quantity, and synchronously samples the channels to be tested; according to the sampling results, it is respectively determined whether there is DC offset, amplitude offset, and angular difference offset, and when at least one of them occurs, it is determined that the ADC sampling consistency test is unqualified. This technical solution can realize the test of the sampling consistency of multiple channels of the analog-to-digital conversion chip.

Description

Technical Field

[0001] The present invention belongs to the field of relay protection in power systems, and more particularly, relates to a method and system for evaluating the sampling consistency of multiple channels of an ADC in a relay protection device. Background Art

[0002] Verifying the sampling consistency of the ADC is of great significance for improving the calculation accuracy of relay protection. On the premise that the ADC sampling consistency meets the conventional requirements, the relay protection usually does not distinguish and set the gain coefficients and angular difference coefficients of each channel of the analog-to-digital conversion chip. That is, for each sampling channel of the same analog-to-digital conversion chip, the same gain coefficient and angular difference coefficient are used for compensation. When the sampling consistency of each channel of this chip is poor, the channel with a large offset will cause inaccurate amplitude and vector calculations of the relay protection, affecting the protection discrimination. Therefore, when the selected analog-to-digital conversion chip does not fully and reliably meet the requirements of relay protection, it is necessary to test the multi-channel sampling consistency of the chip.

[0003] The above information disclosed in the background art section is only used to enhance the understanding of the background of the present invention, and thus it may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and system for evaluating the sampling consistency of multiple channels of an ADC in a relay protection device, which can realize the inspection of the multi-channel sampling consistency of the analog-to-digital conversion chip.

[0005] To achieve the above object, the solution of the present invention is as follows:

[0006] A method for evaluating the sampling consistency of multiple channels of an ADC in a relay protection device includes the following steps:

[0007] Subject each channel to be tested to the same external AC analog quantity excitation, and synchronously sample each channel to be tested;

[0008] According to the sampling results, respectively determine whether there is DC offset, amplitude offset, and angular difference offset. When at least one of them occurs, it is determined that the ADC sampling consistency test is unqualified.

[0009] Specifically, subjecting each channel to be tested to the same external AC analog quantity excitation includes connecting all current channels to be tested in series and connecting all voltage channels to be tested in parallel, applying the same AC analog quantity to each channel to be tested, and subjecting each channel to be tested to the same external AC analog quantity excitation.

[0010] Specifically, determining whether there is DC offset includes obtaining the sum of the instantaneous sampling values of each sampling channel within N cycles with a duration of, and the expression is:

[0011]

[0012] Wherein, X im is the instantaneous value of the i-th sampling point in the sampling sequence of the m-th channel, n is the total number of sampling points in N periods, and P dcm is the sum of the sampling instantaneous values of the m-th channel; N is a set parameter, and its value range is [1, 10];

[0013] Take the maximum value among the sum of each channel of the same type and denote it as P dcmax , and take the minimum value among the sum of each channel of the same type and denote it as P dcmin , if it is determined that a DC offset occurs, and P dtset is a set parameter, and its value range is 0.05 to 0.2 times the peak value of the applied analog quantity.

[0014] Specifically, to determine whether an amplitude offset occurs, including, record the number of sampling points per cycle as X, form a moving sampling data window with X consecutive sampling points, and within N consecutive sampling periods, obtain the Fourier integral of the m-th channel within this moving sampling data window at the test frequency to form an amplitude sequence [P amp_m_1 , P amp_m_2 , P amp_m_3 ,..., P amp_m_x , and obtain the arithmetic mean P amp_m_ave ;

[0015] Record the minimum value of the arithmetic means of the amplitude sequences of all channels as P amp_1_ave , divide the arithmetic means of the amplitude sequences of the remaining channels by P amp_1_ave respectively, if the obtained quotient is greater than or equal to P ampset , it is determined that an amplitude offset occurs, and P ampset is a set parameter, and its value range is [1.005, 1.1].

[0016] Specifically, to determine whether an angular difference offset occurs, including, record the number of sampling points per cycle as X, form a moving sampling data window with X consecutive sampling points, and within N consecutive sampling periods, apply the Fourier integral to obtain the phase angle of the m-th channel within this moving sampling data window at the test frequency to form a phase angle sequence [P vec_m_1 , P vec_m_2 , P vec_m_3 ,..., P vec_m_x ;

[0017] Subtract the phase angle sequence values of the m-th channel from those of the first channel respectively to obtain a phase angle difference sequence [P dtvec_m_1 , P dtvec_m_2 , P dtvec_m_3 ,..., P dtvec_m_x, if in the phase angle difference sequence, there is a calculated value greater than or equal to P vecset , it is determined that an angular difference offset has occurred, and P vecset is a set parameter, with the unit of ° and the value range of [0.1, 5].

[0018] A multi-channel ADC sampling consistency evaluation system for a relay protection device, including

[0019] An AC analog external loop application module configured to make each channel to be tested under the same external AC analog excitation;

[0020] A first discrimination module configured to judge whether a DC offset occurs according to the synchronous sampling results of each channel to be tested;

[0021] A second discrimination module configured to judge whether an amplitude offset occurs according to the synchronous sampling results of each channel to be tested;

[0022] A third discrimination module configured to judge whether an angular difference offset occurs according to the synchronous sampling results of each channel to be tested; and

[0023] A logic judgment module configured to judge that the ADC sampling consistency test fails according to the judgment results of the first to third discrimination modules when at least one of them occurs.

[0024] The above AC analog external loop application module makes each channel to be tested under the same external AC analog excitation, including connecting all current channels to be tested in series and all voltage channels to be tested in parallel, applying the same AC analog quantity to each channel to be tested, and making each channel to be tested under the same external AC analog excitation.

[0025] The above first discrimination module judges whether a DC offset occurs according to the synchronous sampling results of each channel to be tested, including obtaining the sum of the instantaneous sampling values of each sampling channel within N cycles with a duration of, and the expression is:

[0026]

[0027] In the formula, X im is the instantaneous value of the i-th sampling point in the sampling sequence of the m-th channel, n is the total number of sampling points in N cycles, and P dcm is the sum of the instantaneous sampling values of the m-th channel; N is a set parameter, and the value range is [1, 10];

[0028] Denote the maximum value among the sum of each channel of the same type as P dcmax Denote the minimum value among the sum of each channel of the same type as P dcmin , if it is determined that a DC offset occurs, and P dtsetIt is a set parameter, and its value range is 0.05 to 0.2 times the peak value of the applied analog quantity.

[0029] The above-mentioned second discrimination module determines whether amplitude offset occurs according to the synchronous sampling results of each channel to be tested, including: recording the number of sampling points per cycle as X, forming a moving sampling data window with X consecutive sampling points, and within N consecutive sampling cycles, obtaining the Fourier integral of the m-th channel in this moving sampling data window at the test frequency, forming an amplitude sequence [P amp_m_1 , P amp_m_2 , P amp_m_3 ,..., P amp_m_x , and obtaining the arithmetic mean P of the amplitude sequence amp_m_ave ;

[0030] Recording the minimum value of the arithmetic means in the amplitude sequences of all channels as P amp_1_ave , and dividing the arithmetic means of the amplitude sequences of the remaining channels by P amp_1_ave respectively. If the obtained quotient is greater than or equal to P ampset , it is determined that amplitude offset occurs. P ampset is a set parameter, and its value range is [1.005, 1.1].

[0031] The above-mentioned third discrimination module determines whether phase angle difference offset occurs according to the synchronous sampling results of each channel to be tested, including: recording the number of sampling points per cycle as X, forming a moving sampling data window with X consecutive sampling points, and within N consecutive sampling cycles, applying Fourier integral to obtain the phase angle of the m-th channel in this moving sampling data window at the test frequency, forming a phase angle sequence [P vec_m_1 , P vec_m_2 , P vec_m_3 ,..., P vec_m_x ;

[0032] Subtracting the phase angle sequence values of the m-th channel from those of the first channel respectively to obtain a phase angle difference sequence [P dtvec_m_1 , P dtvec_m_2 , P dtvec_m_3 ,..., P dtvec_m_x . If there is a calculated value in the phase angle difference sequence that is greater than or equal to P vecset , it is determined that phase angle difference offset occurs. P vecset is a set parameter, with the unit of °, and its value range is [0.1, 5].

[0033] After adopting the above scheme, the present invention enables each channel to be tested to be under the same external AC analog quantity excitation, compares the sampling calculation values of each channel to be tested of the ADC sampling chip, and when traditional relay protection uses the same gain coefficient and phase angle difference coefficient for supplementation, it can check the sampling consistency of each sampling channel of the relay protection according to the channels. Description of the Drawings

[0034] Figure 1 is the schematic diagram of the present invention. Detailed Embodiments

[0035] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. Like reference numerals in the figures denote like or similar parts, and thus their repetitive description will be omitted.

[0036] The features, structures, or characteristics described may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the present disclosure. However, those skilled in the art will realize that the technical solutions of the present disclosure can be practiced without one or more of these specific details, or other methods, components, materials, devices, etc. may be used. In these cases, well-known structures, methods, devices, implementations, materials, or operations will not be shown or described in detail.

[0037] The flowcharts shown in the drawings are merely illustrative and not necessarily include all the content and operations / steps, nor are they necessarily executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to the actual situation.

[0038] The terms "first", "second", etc. in the specification and claims of the present invention and the above drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products, or devices.

[0039] Those skilled in the art can understand that the drawings are only schematic diagrams of the example embodiments, and the modules or processes in the drawings are not necessarily essential for implementing the present invention, so they cannot be used to limit the protection scope of the present invention.

[0040] An embodiment of the present invention provides a method for evaluating the sampling consistency of multiple channels of an ADC in a relay protection device, including the following steps:

[0041] Step 1: Connect all the current channels to be tested in series and all the voltage channels to be tested in parallel, and apply the same AC analog quantity to each channel to be tested, so that each channel to be tested is under the excitation of the same external AC analog quantity;

[0042] Step 2: Synchronously sample each channel to be tested. According to the sampling results, respectively judge whether there is DC offset, amplitude offset, and angular difference offset. When at least one of them occurs, it is determined that the ADC sampling consistency test fails;

[0043] The content of judging whether there is DC offset is to obtain the sum of the instantaneous sampling values of each sampling channel within N cycles with a duration of X, and the expression is:

[0044]

[0045] In the formula, X im is the instantaneous value of the i-th sampling point in the sampling sequence of the m-th channel, n is the total number of sampling points in N cycles, and P dcm is the sum of the instantaneous sampling values of the m-th channel; N is a set parameter, and the value range is [1, 10];

[0046] Take the maximum value of the sums of each channel of the same type as P dcmax and take the minimum value of the sums of each channel of the same type as P dcmin If it is determined that there is DC offset, and P dtset is a set parameter, and the value range is 0.05 to 0.2 times the peak value of the applied analog quantity.

[0047] The content of judging whether there is amplitude offset is to record the number of sampling points per cycle as X, form a moving sampling data window with X consecutive sampling points, and within N consecutive sampled cycles, obtain the Fourier integral of the m-th channel at the test frequency within this moving sampling data window to form an amplitude sequence [P amp_m_1 , P amp_m_2 , P amp_m_3 ,..., P amp_m_x , and obtain the arithmetic mean P amp_m_ave of the amplitude sequence;

[0048] Record the arithmetic mean of the amplitude sequence of the first channel as P amp_1_ave , divide the arithmetic means of the amplitude sequences of the remaining channels by P amp_1_ave respectively. If the obtained quotient is greater than or equal to P ampset , it is determined that there is an amplitude gain deviation and amplitude offset occurs, and P ampset is a set parameter, and the value range is [1.005, 1.1].

[0049] The content of determining whether angular difference offset occurs is as follows: Denote the number of sampling points per cycle as X, form a moving sampling data window with X consecutive sampling points, and within N consecutive sampling cycles, apply Fourier integral to obtain the phase angle of the m-th channel within this moving sampling data window at the test frequency, thereby forming a phase angle sequence [P vec_m_1 , P vec_m_2 , P vec_m_3 ,..., P vec_m_x ;

[0050] Subtract the phase angle sequence values of the m-th channel from those of the first channel respectively to obtain a phase angle difference sequence [P dtvec_m_1 , P dtvec_m_2 , P dtvec_m_3 ,..., P dtvec_m_x . If there exists a calculated value in the phase angle difference sequence that is greater than or equal to P vecset , it is determined that angular difference offset has occurred. P vecset is a set parameter, with the unit of ° and the value range of [0.1, 5].

[0051] Another embodiment of the present invention provides a multi-channel ADC sampling consistency evaluation system for a relay protection device, including:

[0052] An AC analog quantity external loop application module, configured to apply the same AC analog quantity to each channel to be tested; specifically, connect all current channels to be tested in series and all voltage channels to be tested, and apply the same AC analog quantity to each channel to be tested, so that each channel to be tested is under the excitation of the same external AC analog quantity;

[0053] A first discrimination module, configured to judge whether DC offset occurs according to the synchronous sampling results of each channel to be tested;

[0054] A second discrimination module, configured to judge whether amplitude offset occurs according to the synchronous sampling results of each channel to be tested;

[0055] A third discrimination module, configured to judge whether angular difference offset occurs according to the synchronous sampling results of each channel to be tested; and,

[0056] A logic judgment module, configured to judge that the ADC sampling consistency test is unqualified according to the judgment results of the first to third discrimination modules when at least one of them occurs.

[0057] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) that contain computer-usable program code. The solutions in the embodiments of the present invention can be implemented in various computer languages. For example, object-oriented programming languages such as Java and interpreted scripting languages such as JavaScript, etc.

[0058] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0059] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing devices to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0060] These computer program instructions can also be loaded onto a computer or other programmable data processing devices, such that a series of operation steps are executed on the computer or other programmable devices to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable devices provide steps for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0061] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0062] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for evaluating the sampling consistency of multi-channel ADCs in a relay protection device, characterized in that It includes the following steps: Under the same external AC analog excitation, synchronously sample each channel to be tested; Based on the sampling results, respectively determine whether there is DC offset, amplitude offset, or angular difference offset. When at least one of them occurs, it is determined that the ADC sampling consistency test fails; Among them, determining whether there is DC offset includes obtaining the sum of the instantaneous sampling values of each sampling channel within N cycles with a duration of X, and the expression is: where X im is the instantaneous value of the i-th sampling point in the sampling sequence of the m-th channel, n is the total number of sampling points in N periods, and P dcm is the sum of the sampling instantaneous values of the m-th channel; N is a set parameter, and its value range is [1, 10]; Record the maximum value among the accumulated sums of each channel of the same type as P dcmax ,and record the minimum value among the accumulated sums of each channel of the same type as P dcmin ,if it is determined that a DC offset has occurred, P dtset is a set parameter, and its value range is 0.05 to 0.2 times the peak value of the applied analog quantity; Among them, determining whether amplitude offset occurs includes: recording the number of sampling points per cycle as X, forming a moving sampling data window with X consecutive sampling points, and within N consecutive sampling cycles, obtaining the Fourier integral of the m-th channel within the moving sampling data window at the test frequency to form an amplitude sequence [P amp_m_1 , P amp_m_2 , P amp_m_3 ,..., P amp_m_x , and obtaining the arithmetic mean P of the amplitude sequence amp_m_ave ; Denote the minimum arithmetic mean value of the amplitude sequences in all channels as P amp_1_ave , and divide the arithmetic mean values of the amplitude sequences of the remaining channels by P amp_1_ave respectively. If the obtained quotient is greater than or equal to P ampset , it is determined that amplitude offset occurs. P ampset is a set parameter, and its value range is [1.005, 1.1]; Among them, determining whether angular difference offset occurs includes: recording the number of sampling points per power frequency cycle as X, forming a moving sampling data window with X consecutive sampling points, and within N consecutive sampling periods, applying Fourier integral to obtain the phase angle of the m-th channel within the moving sampling data window at the test frequency, and forming a phase angle sequence [P vec_m_1 , P vec_m_2 , P vec_m_3 ,..., P vec_m_x ; Subtract the phase angle sequence values of the m-th channel from those of the first channel respectively to obtain a phase angle difference sequence [P dtvec_m_1 , P dtvec_m_2 , P dtvec_m_3 ,..., P dtvec_m_x . If there is a calculated value greater than or equal to P vecset in the phase angle difference sequence, it is determined that an angular difference offset has occurred. P vecset is a set parameter with the unit of ° and the value range of [0.1, 5].

2. The method according to claim 1, wherein: Under the same external AC analog excitation, including connecting all current channels to be tested in series and all voltage channels to be tested in parallel, applying the same AC analog quantity to each channel to be tested, so that each channel to be tested is under the same external AC analog excitation.

3. A multi-channel ADC sampling consistency evaluation system for a relay protection device, characterized in that: Including, An external loop application module for AC analog quantity, configured to make each channel to be tested under the same external AC analog excitation; A first discrimination module, configured to determine whether there is DC offset according to the synchronous sampling results of each channel to be tested; A second discrimination module, configured to determine whether there is amplitude offset according to the synchronous sampling results of each channel to be tested; A third discrimination module, configured to determine whether there is angular difference offset according to the synchronous sampling results of each channel to be tested; And, A logic judgment module, configured to determine that the ADC sampling consistency test fails when at least one of them occurs according to the judgment results of the first to third discrimination modules; Among them, the first discrimination module determines whether there is DC offset according to the synchronous sampling results of each channel to be tested, including obtaining the sum of the instantaneous sampling values of each sampling channel within N cycles with a duration of X, and the expression is: where X im is the instantaneous value of the i-th sampling point in the sampling sequence of the m-th channel, n is the total number of sampling points in N periods, and P dcm is the sum of the sampling instantaneous values of the m-th channel; N is a set parameter with a value range of [1, 10]; The maximum value among the cumulative sums of each channel of the same type is denoted as P dcmax , and the minimum value among the cumulative sums of each channel of the same type is denoted as P dcmin , if it is determined that a DC offset occurs, P dtset is a set parameter, and its value range is 0.05 to 0.2 times the peak value of the applied analog quantity; Among them, the second discrimination module determines whether an amplitude offset occurs according to the synchronous sampling results of each channel to be tested, including: recording the number of sampling points per cycle as X, forming a moving sampling data window with X consecutive sampling points, and within N consecutive sampling cycles, obtaining the Fourier integral of the m-th channel in the moving sampling data window at the test frequency, and forming an amplitude sequence [P amp_m_1 , P amp_m_2 , P amp_m_3 ,..., P amp_m_x , obtaining the arithmetic mean P of the amplitude sequence amp_m_ave ; Denote the minimum arithmetic mean value in the amplitude sequences of all channels as P amp_1_ave , and divide the arithmetic mean values of the amplitude sequences of the remaining channels by P amp_1_ave respectively. If the obtained quotient is greater than or equal to P ampset , it is determined that amplitude offset occurs. P ampset is a set parameter, and its value range is [1.005, 1.1]; Among them, the third discrimination module determines whether angular difference offset occurs according to the synchronous sampling results of each channel to be tested, including: recording the number of sampling points per cycle as X, forming a moving sampling data window with X consecutive sampling points, and within N consecutive sampling periods, applying Fourier integral to obtain the phase angle of the m-th channel within the moving sampling data window at the test frequency, forming a phase angle sequence [P vec_m_1 , P vec_m_2 , P vec_m_3 , …, P vec_m_x ; The phase angle sequence values of the m-th channel are respectively subtracted from the phase angle sequence of the first channel to obtain a phase angle difference sequence [P dtvec_m_1 , P dtvec_m_2 , P dtvec_m_3 , …, P dtvec_m_x . If there is a calculated value greater than or equal to P vecset in the phase angle difference sequence, it is determined that an angular difference offset has occurred. P vecset is a set parameter with the unit of ° and the value range of [0.1, 5].

4. The system according to claim 3, characterized in that: The external loop application module for AC analog quantity makes each channel to be tested under the same external AC analog excitation, including connecting all current channels to be tested in series and all voltage channels to be tested in parallel, applying the same AC analog quantity to each channel to be tested, so that each channel to be tested is under the same external AC analog excitation.

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