CN112444698A - Method for detecting abnormal measurement of electrical quantity of extra-high voltage direct current transmission system - Google Patents
Method for detecting abnormal measurement of electrical quantity of extra-high voltage direct current transmission system Download PDFInfo
- Publication number
- CN112444698A CN112444698A CN202011286998.8A CN202011286998A CN112444698A CN 112444698 A CN112444698 A CN 112444698A CN 202011286998 A CN202011286998 A CN 202011286998A CN 112444698 A CN112444698 A CN 112444698A
- Authority
- CN
- China
- Prior art keywords
- direct current
- extra
- high voltage
- time interval
- voltage direct
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
Abstract
The invention discloses a method for detecting abnormal measurement of electrical quantity of an extra-high voltage direct current transmission system, which specifically comprises the following steps: acquiring a measured value sequence X1 of two loopsNAnd X2NAnd calculating the difference Y between the twoNAnd each point y in the sequencei(i is more than 0 and less than or equal to N) probability density function P (y)i) (ii) a Respectively calculating the difference value Y of the measured values of the last time intervalNMean value of (a)0Sum variance
And the mean value mu of the measured value difference of the time interval1Sum variance
Calculating any point y in the time intervaliLog-likelihood ratio z (y) of preceding and following time windowsi) (ii) a Calculating the cumulative sum S of log-likelihood ratios of the time intervalN(ii) a S calculated in step 4NAnd the measured value mutation threshold hAnd comparing to judge whether alarm information needs to be output or not. The problems of slow detection and poor reliability of the electrical quantity measurement abnormity detection and judgment method in the prior art are solved.
Description
Technical Field
The invention relates to the technical field of high-voltage direct-current transmission of a power system, in particular to a method for detecting abnormal measurement of electric quantity of an extra-high voltage direct-current transmission system.
Background
In a common extra-high voltage direct current transmission system, two independent and mutually redundant measurement loops are generally adopted for measuring the same electrical measurement point for electrical measurement, so that the reliability of electrical measurement is improved. The measurement abnormity judging method comprises the steps of solving the absolute value delta diff of the difference of the measured values obtained by the two measurement loops, and if the difference value is out of limit, the two measurement loops are over large in deviation and abnormal. However, this method cannot quickly detect the following two measurement anomalies:
1. the measurement accuracy is reduced due to aging of the measurement circuit equipment. At the moment, the measured value variance is greatly increased compared with the normal working condition, the measured value variance can go through the process from small to large, and the traditional difference-calculating comparison method has to wait for the deviation to exceed the threshold value for detection, so that the detection is slow, and the arrangement of maintenance and replacement in a construction period is not facilitated.
2. The abnormality of the electrical measurement points causes the simultaneous abnormality of the two measurement loops. Because the two measuring loops measure the same electrical measuring point, if the high-voltage equipment (light CT and light PT) at the measuring point is abnormal, the measured values obtained by the two measuring loops are abnormal at the same time, so that the traditional difference-calculating comparison method cannot detect the abnormal difference.
In summary, the conventional measurement anomaly detection and judgment method is slow in detection and poor in reliability.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for detecting the abnormal measurement of the electrical quantity of an extra-high voltage direct current transmission system, which solves the problems of slow detection and poor reliability of the abnormal measurement and judgment method of the electrical quantity in the prior art.
The invention discloses a method for detecting abnormal measurement of electrical quantity of an extra-high voltage direct current transmission system, which specifically comprises the following steps:
s1: acquiring a measured value sequence X1 of two loopsNAnd X2NAnd calculating the difference Y between the twoNAnd each point y in the sequencei(i is more than 0 and less than or equal to N) probability density function P (y)i)；
S2: respectively calculate the last hourDifference value Y between interval measurement valuesNMean value of (a)0Sum variance
And the mean value mu of the measured value difference of the time interval1Sum variance
S3: calculating any point y in the time intervaliLog-likelihood ratio z (y) of preceding and following time windowsi)；
S4: calculating the cumulative sum S of log-likelihood ratios of the time intervalN；
S5: s calculated in step 4NAnd comparing the measured value mutation threshold h to judge whether alarm information needs to be output or not.
In S1, Y isNThe algorithm is specifically as follows:
acquiring a measured value sequence X1 with the length of N from two sets of independent and mutually redundant measuring loops of an extra-high voltage direct current transmission system at a certain moment according to time sequenceNAnd X2NLet X1NAnd X2NAre independent and equally distributed random sequences, the difference value Y of the two sequencesNComprises the following steps: y isN＝X1N-X2N。
In S1, P (y) according to one embodiment of the present inventioni) The algorithm is specifically as follows:
is provided with YNIs a mean value of mu and a variance of sigma2Is independently and identically distributed random sequence of each point y in the sequenceiProbability density function P (y) of (0 < i ≦ N)i) Following a normal distribution, there are:
in S2, the mean value is calculated according to the following formula
The variance is calculated as:
according to an embodiment of the present invention, the arbitrary point y in S3iLog-likelihood ratio z (y) of preceding and following time windowsi) The calculation formula of (2) is as follows:
wherein:
according to an embodiment of the present invention, the sum of the log-likelihood ratios S4NThe calculation formula of (2) is as follows:
according to an embodiment of the present invention, the specific determination process of S5 is:
s5.1: suppose that the difference between the measured values in this time interval is abruptly changed at point v, i.e., y1，y2，...yvThe distribution conforms to a known probability density function f, let yv+1，yv+2，...yNConforms to a probability density function g, and
v can be at any time, two assumptions are made:
the original assumption is that: hk：v＝k，0≤k＜N
The alternative assumption is that: h∞：v＝∞
The discrimination criteria of the test are:
if d is equal to 0, the measured value in the time interval is judged not to have mutation and is marked as H∞，
If d is equal to 1, the measured value in the time interval is judged to have mutation and is marked as Hk，
Wherein h is the measured value mutation threshold;
s5.2: the result of determination is H∞And ending;
s5.2: the result of determination is HkMeanwhile, in the time interval of data acquisition in S2, the extra-high voltage direct current system meets all the following conditions in the whole process:
1) the valve block/pole where the measured electrical quantity is located is in operation
2) The converter transformer is in the state of stopping gear shifting
3) The control system is in a power regulation stop state
4) The reduced-voltage operating mode is not activated
5) Direct current protection does not act
The reason for causing the sudden change of the measured value is irrelevant to the change of the system running condition, and alarm information is output for the abnormal occurrence of the measuring loop.
According to an embodiment of the present invention, the calculation methods of S1-S5 employ CUSUM-based algorithms.
The method is used for detecting the abnormity in the process of measuring the electrical quantity of the ultra-high voltage direct current transmission system based on CUSUM (cumulative sum) algorithm, can quickly identify the abnormity such as the reduction of the precision of the measured value, the abnormity of high-voltage equipment of the electrical measured value and the like besides the deviation of two paths of measured values, and is more complete in coverage than the traditional detection method and more rapid and reliable in detection.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
FIG. 1 is a flow chart of a method for detecting abnormal measurement of electrical quantity in an extra-high voltage DC power transmission system according to the present invention;
FIG. 2 shows the difference between two UdH measurement values in the time interval in the method for detecting abnormal measurement of electrical quantity of an UHVDC transmission systemYNA graph of (a);
FIG. 3 shows a difference Y between two UdH measurement values in a previous time interval in an embodiment of a method for detecting abnormal measurement of electrical quantity of an extra-high voltage direct current transmission system according to the inventionNA graph of (a).
Detailed Description
In the following description, for purposes of explanation, numerous implementation details are set forth in order to provide a thorough understanding of the various embodiments of the present invention. It should be understood, however, that these implementation details are not to be interpreted as limiting the invention. That is, in some embodiments of the invention, such implementation details are not necessary. In addition, some conventional structures and components are shown in simplified schematic form in the drawings.
In addition, the descriptions related to the first, the second, etc. in the present invention are only used for description purposes, do not particularly refer to an order or sequence, and do not limit the present invention, but only distinguish components or operations described in the same technical terms, and are not understood to indicate or imply relative importance or implicitly indicate the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
The invention discloses a method for detecting abnormal measurement of electrical quantity of an extra-high voltage direct current transmission system, which adopts an algorithm based on CUSUM, and the flow is shown in figure 1, and the method specifically comprises the following steps:
s1: acquiring a measured value sequence X1 of two loopsNAnd X2NAnd calculating the difference Y between the twoNAnd each point y in the sequencei(i is more than 0 and less than or equal to N) probability density function P (y)i)：
YNIs specifically calculatedComprises the following steps: acquiring a measured value sequence X1 with the length of N from two sets of independent and mutually redundant measuring loops of an extra-high voltage direct current transmission system at a certain moment according to time sequenceNAnd X2NLet X1NAnd X2NAre independent and equally distributed random sequences, the difference value Y of the two sequencesNComprises the following steps: y isN＝X1N-X2N；
P(yi) The algorithm is specifically as follows: is provided with YNIs a mean value of mu and a variance of sigma2Is independently and identically distributed random sequence of each point y in the sequenceiProbability density function P (y) of (0 < i ≦ N)i) Following a normal distribution, there are:
s2: respectively calculating the difference value Y of the measured values of the last time intervalNMean value of (a)0Sum variance
And the mean value mu of the measured value difference of the time interval1Sum variance
Wherein the mean value is calculated by the formula
The variance is calculated as:
s3: calculating any point y in the time intervaliLog-likelihood ratio z (y) of preceding and following time windowsi)，
Wherein:
s4: calculating the cumulative sum S of log-likelihood ratios of the time intervalN，
S5: s calculated in step 4NComparing the measured value mutation threshold h to judge whether alarm information needs to be output or not;
s5.1: suppose that the difference between the measured values in this time interval is abruptly changed at point v, i.e., y1，y2，...yvThe distribution conforms to a known probability density function f, let yv+1，yv+2，...yNConforms to a probability density function g, and
v can be at any time, two assumptions are made:
the original assumption is that: hk：v＝k，0≤k＜N
The alternative assumption is that: h∞：v＝∞
The discrimination criteria of the test are:
if d is equal to 0, the measured value in the time interval is judged not to have mutation and is marked as H∞，
If d is equal to 1, the measured value in the time interval is judged to have mutation and is marked as Hk，
Wherein h is the measured value mutation threshold;
s5.2: the result of determination is H∞And ending;
s5.2: the result of determination is HkMeanwhile, in the time interval of data acquisition in S2, the extra-high voltage direct current system meets all the following conditions in the whole process:
1) the valve block/pole where the measured electrical quantity is located is in operation
2) The converter transformer is in the state of stopping gear shifting
3) The control system is in a power regulation stop state
4) The reduced-voltage operating mode is not activated
5) Direct current protection does not act
The reason for causing the sudden change of the measured value is irrelevant to the change of the system running condition, and alarm information is output for the abnormal occurrence of the measuring loop.
Example (b):
taking the measurement of voltage UdH of a high-end direct-current line of a pole I of a Pu' er converter station of +/-800 kV as an example.
S1: the UdH measured value sequence X1 of 1 hour is respectively collected from two sets of measuring systems of the stationNAnd X2NUsing the formula YN＝X1N-X2NFind out the difference YN，YNThe sequence curves are shown in FIG. 2.
S2: calculating the time interval Y from the curve dataNMean value of (a)1Is-0.642, variance
Is 21.762.
The difference of UdH measured values recorded 1 hour before the two sets of measuring systems at the station is shown in FIG. 3, and the last time interval Y is calculated according to the differenceNMean value of (a)0Is-0.400, variance
Is 7.756.
S3: according to the formula
Calculate the time interval YNLog-likelihood ratio z (y) of each point in the preceding and following time windowsi)。
S4: calculating the cumulative sum S of the log-likelihood ratios of the time intervalNWas 21.101.
S5: assuming that the measurement value mutation threshold h is 1.0, the cumulative sum is obtained at S4 as 5NIt is known that the sum S is accumulated at 6841 th sampling pointNOut-of-limit, i.e. the measured value has a sudden change in this time interval and is marked as Hk。
Acquiring the running state of the direct current control protection system in the time interval, and judging whether the following conditions are met in the whole process:
1) the polar I double valve group is in operation
2) All converter transformers of pole I are in the state of stopping gear shifting
3) The control system is in a power regulation stop state
4) The control system is not activated in the step-down operation mode
5) Non-operation of DC protection system
And if so, outputting alarm information.
The above description is only an embodiment of the present invention, and is not intended to limit the present invention. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (9)
1. The method for detecting the abnormal measurement of the electric quantity of the extra-high voltage direct current transmission system is characterized by comprising the following steps:
s1: acquiring a measured value sequence X1 of two loopsNAnd X2NAnd calculating the difference Y between the twoNAnd each point y in the sequencei(i is more than 0 and less than or equal to N) probability density function P (y)i)；
S2: respectively calculating the difference value Y of the measured values of the last time intervalNMean value of (a)0Sum variance
And the mean value mu of the measured value difference of the time interval1Sum variance
S3: calculating any point y in the time intervaliLog-likelihood of preceding and following time windowsNatural ratio z (y)i)；
S4: calculating the cumulative sum S of log-likelihood ratios of the time intervalN；
S5: s calculated in step 4NAnd comparing the measured value mutation threshold h to judge whether alarm information needs to be output or not.
2. The method for detecting the abnormal measurement of the electrical quantity of the extra-high voltage direct current transmission system according to claim 1, wherein in the step S1, Y isNThe algorithm is specifically as follows:
acquiring a measured value sequence X1 with the length of N from two sets of independent and mutually redundant measuring loops of an extra-high voltage direct current transmission system at a certain moment according to time sequenceNAnd X2NLet X1NAnd X2NAre independent and equally distributed random sequences, the difference value Y of the two sequencesNComprises the following steps: y isN＝X1N-X2N。
3. The method for detecting the abnormal measurement of the electrical quantity of the extra-high voltage direct current transmission system according to claim 1, wherein in the step S1, P (y) isi) The algorithm is specifically as follows:
is provided with YNIs a mean value of mu and a variance of sigma2Is independently and identically distributed random sequence of each point y in the sequenceiProbability density function P (y) of (0 < i ≦ N)i) Following a normal distribution, there are:
4. the method for detecting the abnormal measurement of the electrical quantity of the extra-high voltage direct current transmission system according to claim 1, wherein in the step S2, the average value calculation formula is
The variance is calculated as:
5. the method for detecting the abnormal measurement of the electrical quantity of the extra-high voltage direct current transmission system according to claim 1, wherein any point y in the S3iLog-likelihood ratio z (y) of preceding and following time windowsi) The calculation formula of (2) is as follows:
wherein:
6. the method for detecting the abnormal measurement of the electrical quantity of the extra-high voltage direct current transmission system according to claim 1, wherein the sum of the cumulative sum of log-likelihood ratios in S4 is SNThe calculation formula of (2) is as follows:
7. the method for detecting the abnormal measurement of the electrical quantity of the extra-high voltage direct current transmission system according to claim 1, wherein the specific judgment process of S5 is as follows:
s5.1: suppose that the difference value of the measured values in the time interval is suddenly changed at the v point, namely y1，y2，...yνThe distribution conforms to a known probability density function f, let yv+1，yv+2，...yNConforms to a probability density function g, and
v can be at any time, two assumptions are made:
the original assumption is that: hk：v＝k，0≤k＜N
The alternative assumption is that: h∞：ν＝∞
The discrimination criteria of the test are:
if d is equal to 0, the measured value in the time interval is judged not to have mutation and is marked as H∞，
If d is equal to 1, the measured value in the time interval is judged to have mutation and is marked as Hk，
Wherein h is the measured value mutation threshold;
s5.2: the result of determination is H∞And ending;
s5.2: the result of determination is HkMeanwhile, in the time interval of data acquisition in S2, the extra-high voltage direct current system meets all the following conditions in the whole process:
1) the valve block/pole where the measured electrical quantity is located is in operation
2) The converter transformer is in the state of stopping gear shifting
3) The control system is in a power regulation stop state
4) The reduced-voltage operating mode is not activated
5) Direct current protection does not act
The reason for causing the sudden change of the measured value is irrelevant to the change of the system running condition, and alarm information is output for the abnormal occurrence of the measuring loop.
8. The method for detecting the abnormal measurement of the electrical quantity of the extra-high voltage direct current transmission system according to claim 7, wherein the alarm information output in the step S5.2 is as follows: if the xxx measurement acquisition is abnormal, please check the measurement loop.
9. The method for detecting the abnormal measurement of the electrical quantity of the extra-high voltage direct current transmission system according to claim 1, wherein the calculation method from S1 to S5 adopts a CUSUM-based algorithm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011286998.8A CN112444698A (en) | 2020-11-17 | 2020-11-17 | Method for detecting abnormal measurement of electrical quantity of extra-high voltage direct current transmission system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011286998.8A CN112444698A (en) | 2020-11-17 | 2020-11-17 | Method for detecting abnormal measurement of electrical quantity of extra-high voltage direct current transmission system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112444698A true CN112444698A (en) | 2021-03-05 |
Family
ID=74738617
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011286998.8A Pending CN112444698A (en) | 2020-11-17 | 2020-11-17 | Method for detecting abnormal measurement of electrical quantity of extra-high voltage direct current transmission system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112444698A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116502156A (en) * | 2023-06-30 | 2023-07-28 | 中国电力科学研究院有限公司 | Intelligent identification method and system for light CT abnormal state of converter station |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103795144A (en) * | 2013-11-22 | 2014-05-14 | 深圳供电局有限公司 | Fault recording data-based power system disturbance occurrence time identification method |
| CN109409661A (en) * | 2018-09-19 | 2019-03-01 | 平安科技（深圳）有限公司 | Electronic device, the building Electrical Safety recognition methods based on cusum algorithm and storage medium |
-
2020
- 2020-11-17 CN CN202011286998.8A patent/CN112444698A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103795144A (en) * | 2013-11-22 | 2014-05-14 | 深圳供电局有限公司 | Fault recording data-based power system disturbance occurrence time identification method |
| CN109409661A (en) * | 2018-09-19 | 2019-03-01 | 平安科技（深圳）有限公司 | Electronic device, the building Electrical Safety recognition methods based on cusum algorithm and storage medium |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116502156A (en) * | 2023-06-30 | 2023-07-28 | 中国电力科学研究院有限公司 | Intelligent identification method and system for light CT abnormal state of converter station |
| CN116502156B (en) * | 2023-06-30 | 2023-09-08 | 中国电力科学研究院有限公司 | Intelligent identification method and system for light CT abnormal state of converter station |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Kang et al. | Condition monitoring of power transformer on-load tap-changers. Part 2: Detection of ageing from vibration signatures | |
| CN110323773B (en) | Commutation failure prediction method and system considering multi-factor influence | |
| CN101432941B (en) | Load compensation in distance protection of three-phase electric power line | |
| CN111189645B (en) | Method and system for performing diagnostic procedures with reduced processing time | |
| CN111465866A (en) | Sensor fault detection using paired sample correlations | |
| CN112444698A (en) | Method for detecting abnormal measurement of electrical quantity of extra-high voltage direct current transmission system | |
| WO2020253301A1 (en) | Method for redundant sampling and abnormality determination for relay protection | |
| WO2009095156A1 (en) | Method of determining a polarization curve of a fuel cell system, and method of operating a fuel cell system and fuel cell system | |
| CN109375103A (en) | Three-phase brushless dc motor inverter power pipe single tube open-circuit fault diagnostic method | |
| EP3330858B1 (en) | On-board control device, on-board integrated circuit | |
| CN109085460B (en) | Ultra-high voltage direct current transmission line fault single-end diagnosis method based on transient quantity monitoring | |
| KR101724500B1 (en) | Fuel cell stack diagnostic system and diagnostic method thereof | |
| CN114514433A (en) | Apparatus and method for diagnosing battery | |
| US20200153226A1 (en) | Method and device for detecting light arcs | |
| KR20210011235A (en) | Apparatus and method for diagnosing battery cell | |
| CN111505450B (en) | Method and system for judging corona onset field intensity based on ultraviolet photon number | |
| CN110907716B (en) | Method and device for judging voltage deviation isolation effect, power supply system, computer equipment and storage medium | |
| CN114356621A (en) | Bus exit method and device based on information entropy analysis | |
| CN112731103A (en) | Fault diagnosis method of two-stage matrix converter | |
| CN111679233A (en) | Method for positioning measurement abnormity of hybrid direct current engineering control system | |
| JPH0387672A (en) | Diagnostic device for contact | |
| CN115541973B (en) | Method and device for monitoring signal redundancy of high-voltage bus of transformer substation | |
| CN111722116A (en) | Battery management system and detection method thereof | |
| CN115421093B (en) | Method and system for self-recovering measured data of all-fiber current transformer | |
| EP4287486A1 (en) | A method for fixing an output power limit of a frequency converter and a method for diagnosing conditions of dc-link capacitors |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210305 |
|
| RJ01 | Rejection of invention patent application after publication |