CN109885418B - Sampling disturbance filtering-based in-situ transformer protection anti-interference method - Google Patents
Sampling disturbance filtering-based in-situ transformer protection anti-interference method Download PDFInfo
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- CN109885418B CN109885418B CN201910049125.6A CN201910049125A CN109885418B CN 109885418 B CN109885418 B CN 109885418B CN 201910049125 A CN201910049125 A CN 201910049125A CN 109885418 B CN109885418 B CN 109885418B
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- Y04S40/12—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them characterised by data transport means between the monitoring, controlling or managing units and monitored, controlled or operated electrical equipment
- Y04S40/124—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them characterised by data transport means between the monitoring, controlling or managing units and monitored, controlled or operated electrical equipment using wired telecommunication networks or data transmission busses
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Abstract
The invention discloses a sampling disturbance filtering-based local transformer protection anti-interference method, which comprises the steps of obtaining analog quantity information by high-speed sampling at least four times of the actual sampling rate, carrying out sampling disturbance filtering on a sampling value after analog-digital conversion, carrying out abnormal waveform identification by using the change of a sampling slope, carrying out data synchronization with data received by an HSR (high speed record) ring network after the sampling disturbance filtering, using a protection algorithm of a local sub-machine after the data synchronization, and simultaneously sending the data to other sub-machines through the HSR ring network. The method has the advantages of high response speed and strong adaptability, the anti-interference algorithm is directly in the sampling value processing link, and the anti-interference algorithm has no relation with HSR looped network data and the protection algorithm, and does not influence the in-situ transformer protection algorithm.
Description
Technical Field
The invention relates to a sampling disturbance filtering-based local transformer protection anti-interference method, and belongs to the technical field of relay protection.
Background
The new on-site protection technology characterized by sampling digitization, protection on-site, element protection private networking and information sharing is the main technical direction of the intelligent transformer substation of the future national power grid company. The development of low-power chip integration technology and optical fiber communication technology and the breakthrough of key technologies such as electromagnetic compatibility, high protection, thermal design and the like of the device provide a technical basis for implementing an on-site protection scheme. The on-site protection is arranged close to primary equipment on site, and the cable sampling and the direct tripping of the cable are adopted, so that the length of the cable and intermediate links are reduced, and the speed and the reliability of relay protection are improved; based on the standardized design of interface, adopt standard connector, realize protection device's batch production debugging, modularization installation and the maintenance of change formula, reduce secondary equipment installation, debugging and maintenance time, promote operating mass with rated load and efficiency, shorten the power off time.
Referring to fig. 1, the transformer protection is formed by connecting a plurality of protection sub-machines through an independent bidirectional double-loop network, and the protection sub-machines are configured according to sides. The transformer protection sub-machine acquires the analog quantity and the switching value of the side and outputs the split-phase tripping outlet of the switch of the side. The transformer protection submachine receives analog quantity and switching value information collected by other protection submachines through an element protection HSR looped network, and each protection submachine independently completes all protection functions. The protection submachine is arranged close to primary equipment on the spot and is easily influenced by primary equipment operation and ground network interference, so that the sampled data is disturbed, the sampled data is not only used for protecting the submachine, but also used for other submachines in a communication mode, and abnormal data under the interference condition can easily cause misoperation of the transformer protection submachine if algorithm processing is not carried out.
Therefore, in the current situation, an anti-interference algorithm is needed for on-site transformer protection to solve the influence of sampling disturbance on a protection algorithm so as to improve the reliability of on-site transformer protection.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects of the prior art and provide an anti-interference method for protecting an in-situ transformer based on sampling disturbance filtering so as to meet the requirement of the in-situ transformer protection on the reliability in the aspect of electromagnetic compatibility.
In order to solve the technical problem, the invention provides an anti-interference method for protecting an in-place transformer based on sampling disturbance filtering, which comprises the following steps of:
1) sampling current and voltage data in situ;
2) carrying out abnormal disturbance judgment on the sampling data in the step 1);
3) performing interpolation processing on the sampling abnormal data;
4) and synchronously outputting the local sampling data and the external input HSR data.
In the foregoing step 1), a plurality of AD analog-to-digital conversion chips are used to sample current and voltage data, the plurality of AD analog-to-digital conversion chips are used to perform a plurality of sets of concurrent conversion control and data reading modes, a busy indication signal of the AD analog-to-digital conversion chip is enabled at the same time when the conversion starts, corresponding sampled data is obtained in real time after the AD analog-to-digital conversion is finished, and the analog-to-digital conversion is as follows:
wherein S is o For outputting digital values, V, after AD conversion i For input voltage analog, V max Is the voltage input range.
In the step 1), the localized sampling rate is at least four times of the protection actual sampling rate, and 1-4 sampling data windows are delayed.
According to the AD conversion chip power supply and the sampling communication process which are monitored in real time in the sampling process, when the AD conversion chip power supply is low or the sampling communication is abnormal, the sampling error mark is marked.
In the step 2), the abnormal disturbance judgment is performed on the sampled data, and the method includes the following steps:
21) judging whether the current sampling data is effective or not, wherein the judging method comprises the following steps:
wherein S is n In is a rated current for sampling an instantaneous value;
22) and judging the sampling abnormal state under the streaming state of the sampling data, which specifically comprises the following steps:
22-1) calculating the slope of the sampling point:
K n ＝S n -S n-1
wherein, K n Is the slope of the sample point n, S n Is the sampled instantaneous value of a sample point n, S n-1 Is the sampling instantaneous value of the sampling point n-1;
22-2) calculating the slope variation of the sampling point:
ΔK n ＝|K n -K n-1 |
wherein, Δ K n Is the slope variation of the sampling point n, K n Is the slope of the sample point n, K n-1 Is the slope of the sampling point n-1;
22-3) judging whether the sampling points are abnormal or not according to the slope variation of the sampling points, wherein the judgment is as follows:
if the above formula is satisfied, the sampling interference point is defined.
In the step 3), when the sampling interference point is monitored in the step 2), firstly, whether the sampling value can be interpolated is judged, and when the sampling interference point meets the interpolation condition, the sampling interference point is restored by adopting cubic spline interpolation; and when the sampling interference point does not meet the interpolation condition, setting a sampling error flag in real time.
The foregoing interpolation conditions are: if the number of the first continuous sampling data of the current data sampling point is less than or equal to 4 and the number of the preamble continuous effective sampling values is greater than or equal to 2, the sampling point can be interpolated.
In the step 4), after the in-place sampling data and the externally input HSR data are acquired, the interrupt pulse delayed by each sampling output is corrected, the sending counter is cleared at the beginning of each interrupt pulse and automatically increases along with the period of the crystal oscillator, and when the sending counter increases to be consistent with the actual sending time, the corresponding sampling point data is output, so that the time domain uniformity of the in-place sampling data and the externally input HSR data is realized.
The invention has the following beneficial effects:
(1) the response speed is high, the sampling rate of the system is improved, the actual sampling rate is four times of the sampling rate of the protection algorithm, the anti-interference algorithm is implemented in four points, and the response speed of the whole protection algorithm cannot be influenced.
(2) The method has high precision, and the sampling precision of the whole system cannot be sacrificed in the interference processing process by adopting cubic spline interpolation.
(3) The method has strong adaptability, the anti-interference algorithm is directly in the sampling value processing link, and has no relation with HSR looped network data and the protection algorithm, and the in-situ transformer protection algorithm is not influenced.
(4) The method has high synchronization precision, and adopts high sampling rate to carry out sampling interpolation synchronization without sacrificing the frequency precision in a measurable range.
(5) The reliability is high, sampling abnormity is judged by adopting the slope variation, and misjudgment and sampling abnormity cannot be caused in the transient process.
Drawings
FIG. 1 is a schematic diagram of distributed in-situ transformer protection;
FIG. 2 is a flow chart of the method of the present invention;
FIG. 3 is a flowchart illustrating the process of determining and processing sampling abnormal disturbance according to the present invention.
Detailed Description
The invention is further described below. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
The invention provides a sampling disturbance filtering-based in-situ transformer protection anti-interference method, which adopts high-speed sampling at least four times of the actual sampling rate to obtain analog quantity information; sampling disturbance filtering is carried out on the sampling value after analog-digital conversion, and abnormal waveform identification is carried out by utilizing the change of the sampling slope; carrying out data synchronization with HSR looped network received data after sampling disturbance filtering; and after data synchronization, the data is used for the protection algorithm of the submachine and is simultaneously sent to other submachines through the HSR ring network.
Referring to fig. 2, the specific steps are as follows:
the method comprises the following steps: in-situ high-speed sampling current and voltage values
The high-speed AD analog-to-digital conversion chip is adopted, the fast digital sampling capacity is achieved based on the AD sampling rate of 800 points/cycle, the abnormal conditions that the high-frequency component of an original signal is lost, the sampling precision error is large or the sampling data is unstable and the like caused by insufficient sampling rate of an analog loop are avoided, and meanwhile the realization precision of a rear-end algorithm can be effectively improved.
In order to improve the AD sampling frequency, a daisy chain connection sampling mode is not used among a plurality of AD chips, a plurality of groups of conversion control and data reading in a concurrent mode are adopted, a busy indication signal for AD conversion is enabled at the same time when the conversion starts, and corresponding sampling data are obtained in real time after the AD conversion is finished. The AD conversion formula is as follows:
wherein: s o For outputting digital values, V, after AD conversion i For input of an analog quantity of voltage, V max Is the voltage input range.
In the invention, the sampling rate of the high-speed sampling input is at least four times of the protection actual sampling rate, 1-4 sampling data windows are delayed, and the protection actual sampling rate is generally between 24 points/cycle and 96 points/cycle.
Step two: abnormal disturbance judgment is carried out on sampling data
And analyzing the sampling sequence converted and cached in the step, monitoring the rapid pulse interference in a software mode, well inhibiting the double pulse interference, and preventing the problems of protection algorithm misoperation and the like caused by abnormal large-value disturbance of instantaneous sampling. And carrying out sampling disturbance detection processing on the sampling points, and if the sampling points are judged to be interference points, replacing abnormal sampling data with interpolation data through a subsequent algorithm.
Referring to fig. 3, the step of judging abnormal disturbance of the sampled data is divided into two parts:
21) judging whether the current sampling data is effective or not, wherein the judging method comprises the following steps:
wherein: s n In is the rated current for sampling the instantaneous value.
22) And when the flow exists in the sampling, judging the sampling abnormal state, specifically as follows (when the flow does not exist, the processing is not performed):
22-1) calculating the slope of the sampling point:
K n ＝S n -S n-1
wherein: k n Is the slope of the sampling point n, S n Is the sampled instantaneous value of a sample point n, S n-1 Is the sampled instantaneous value of sample point n-1.
22-2) calculating the slope variation of the sampling point:
ΔK n ＝|K n -K n-1 |
wherein: Δ K n Is the slope variation of the sampling point n, K n Is the slope of the sample point n, K n-1 The slope of sample point n-1.
22-3) judging a sampling error mark, if so, resetting the sampling error mark, and directly carrying out protection locking without judging; if not, judging whether the sampling point is abnormal according to the slope variation of the sampling point, and if the slope variation is large but the variation is stable, sampling the higher harmonic; and if the slope variation is large and the slope variation of the previous point is not large, the sampling interference point is determined. The sampling error mark is that the sampling data is not credible according to the abnormal information given by the working state of the AD chip, and the protection locking is directly carried out without judging. The sampling anomaly criterion is as follows:
and if the above expression is satisfied, the sampling interference point is obtained.
The method comprises the following steps of monitoring an AD power supply and an AD sampling communication process in real time in the sampling process, and marking a sampling error sign when the AD module power supply is low or the communication with the AD module is abnormal. The fault-tolerant capability of the protection device to the interference signal is increased.
Step three: exception sampling handling
When the sampling interference point is monitored in the second step, whether the sampling value can be interpolated is judged firstly, and when the sampling interference point meets the interpolation condition, the sampling interference point is restored through a high-precision interpolation algorithm, so that original sampling information data are fitted to the maximum extent; and when the sampling interference point does not meet the interpolation condition, setting a sampling error mark in real time, and avoiding the influence of invalid sampling data caused by sampling disturbance on a transformer protection algorithm.
The interpolation conditions are as follows: if the number of sampling values (the first continuous sampling data of the current data sampling point) of the preamble continuous interpolation is less than or equal to 4 and the number of preamble continuous effective sampling values is greater than or equal to 2, the sampling of the current point can be interpolated, otherwise, the effective sampling information is insufficient, and the interpolation algorithm cannot be used.
The interpolation algorithm is as follows:
and (3) interpolating the original sampling signal by adopting a software interpolation algorithm, and performing fitting interpolation calculation on the original sampling according to the refresh rate of actual output data to obtain a final sampling output discrete sequence.
Carrying out cubic spline interpolation calculation on the sampling value protected by the in-situ transformer, wherein the length of input arrays X and Y is n, X 0 <x 1 <…<x n-1 As shown in the following equation:
f(x i )＝y i
the interpolation function g (x) is a piecewise function in the following equation:
function p i (x) To satisfy a third order polynomial of the following conditions:
g(x i )＝y i ＝p i (x i )
at x i Where the first and second derivatives continue, i ═ 1, …, n-2,
g′(x i )＝p′ i (x i )＝p′ i-1 (x i )
g″(x i )＝p″ i (x i )＝p″ i-1 (x i )
g″(x i ) The second derivative of a cubic interpolation spline function. In the interval [ x i ,x i+1 ]The following equation is the output interpolation y:
y＝Ay i +By i+1 +Cy″ i +Dy″ i+1
wherein:
B＝1-A
step four: multi-source sampling data synchronous output
The analog quantity sampling protected by the localized transformer is an analog-to-digital conversion data sequence with continuous time domain and error value domain, the HSR sampling input from the outside is digital quantity sampling with discrete error time domain and small value domain error, the two samples have essential difference on time domain characteristics, and the difference can exist in the aspects of system frequency, sampling rate, rated delay and the like. Therefore, it is necessary to combine the time domain transmission characteristics of physical sampling and digital sampling to realize synchronous output control of local sampling data and externally input HSR data. The specific implementation mode is as follows:
after the local sampling data and the external HSR sampling data are obtained, synchronous control among different sampling data is realized by correcting the delayed interrupt pulse of each sampling output. The minimum resolution of the output interrupt pulses is determined by an onboard crystal oscillator and is uniformly adjusted by synchronous second pulses in the system, the first interrupt pulse in each synchronous period is initiated by the rising edge of the synchronous second pulse, and the rest interrupt pulses are controlled by an interval counter of a sampling period. And resetting the transmission counter at the beginning of each interrupt pulse, automatically increasing along with the period of the crystal oscillator, and outputting corresponding sampling point data when the transmission counter is increased to be consistent with the actual transmission moment, so that the time domain uniformity of the sampling data can be ensured.
Through the steps from one to four, sampling anti-interference processing of the in-situ transformer protection algorithm is achieved, and reliability and stability of relevant equipment in field operation are improved.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (6)
1. The in-situ transformer protection anti-interference method based on sampling disturbance filtering is characterized by comprising the following steps of:
1) sampling current and voltage data in situ;
2) carrying out abnormal disturbance judgment on the sampling data in the step 1), comprising the following steps:
21) judging whether the current sampling data is effective or not, wherein the judging method comprises the following steps:
wherein S is n The sampling instantaneous value of a sampling point n is shown, and In is rated current;
22) and judging the sampling abnormal state under the streaming state of the sampling data, specifically as follows:
22-1) calculating the slope of the sampling point:
K n ＝S n -S n-1 ，
wherein, K n Is the slope of the sampling point n, S n Is the sampled instantaneous value of a sample point n, S n-1 Is the sampling instantaneous value of the sampling point n-1;
22-2) calculating the slope variation of the sampling point:
ΔK n ＝|K n -K n-1 |，
wherein, Δ K n Is the slope variation of the sampling point n, K n Is the slope of the sample point n, K n-1 Is the slope of the sampling point n-1;
22-3) judging whether the sampling point data is abnormal according to the slope variation of the sampling points, wherein the criterion is as follows:
if the criterion is met, the data is abnormal sampling data;
3) performing interpolation processing on the abnormal sampling data;
4) synchronously outputting locally sampled data and externally input HSR data, comprising:
after local sampling data and external input HSR data are acquired, interrupt pulses of sampling output delay are corrected, a sending counter is cleared at the beginning of each interrupt pulse and automatically increased along with the period of a crystal oscillator, and when the sending counter is increased to be consistent with the actual sending time, corresponding sampling point data are output.
2. The sampling disturbance filtering-based in-place transformer protection anti-interference method according to claim 1, wherein in the step 1), a plurality of AD conversion chips are adopted to sample current and voltage data, the plurality of AD conversion chips adopt a plurality of groups of concurrent conversion control and data reading modes, a busy indication signal of the AD conversion chips is enabled at the same time when the conversion starts, corresponding sampling data is obtained in real time after the AD conversion is finished, and the AD conversion is as follows:
wherein S is o For outputting digital values, V, after AD conversion i For input voltage analog, V max Is the voltage input range.
3. The sampling disturbance filtering based localized transformer protection anti-interference method according to claim 1, wherein in the step 1), the localized sampling rate is at least four times of the protection actual sampling rate, and the delay is 1-4 sampling data windows.
4. The sampling disturbance filtering-based in-place transformer protection anti-interference method according to claim 1, wherein an AD (analog-to-digital) conversion chip power supply and a sampling communication process are monitored in real time in the sampling process, and a sampling error flag is marked when the AD conversion chip power supply is low or the sampling communication is abnormal.
5. The sampling disturbance filtering based anti-interference method for in-place transformer protection according to claim 1, wherein in the step 3), when abnormal sampling data is monitored in the step 2), whether the abnormal sampling data can be interpolated is firstly judged, and when the abnormal sampling data meets an interpolation condition, cubic spline interpolation is adopted to restore the abnormal sampling data; and when the abnormal sampling data does not meet the interpolation condition, setting a sampling error flag in real time.
6. The sampling perturbation filtering based localized transformer protection anti-interference method according to claim 5, wherein the interpolation condition is: if the number of the first few continuous sampling data of the current sampling data is less than or equal to 4 and the number of the preamble continuous effective sampling data is greater than or equal to 2, the sampling data can be interpolated.
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