CN110970878B - Method for improving band-limited time current quick-break precision based on mean filtering - Google Patents
Method for improving band-limited time current quick-break precision based on mean filtering Download PDFInfo
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- CN110970878B CN110970878B CN201911347379.2A CN201911347379A CN110970878B CN 110970878 B CN110970878 B CN 110970878B CN 201911347379 A CN201911347379 A CN 201911347379A CN 110970878 B CN110970878 B CN 110970878B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
- H02H7/262—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations involving transmissions of switching or blocking orders
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Abstract
The invention relates to a method for improving the quick-break precision of a time-limited current based on mean value filtering. The method is characterized by comprising the following steps: (1) multiplying the real effective value subjected to time-limited quick-break to make the real effective value larger than 2 thousandths; (2) and converting the judgment basis after the time-limited quick-break protection into the true effective value data after mean value filtering every ten true effective values. The invention provides a method for improving the quick-break precision of current with delay based on mean value filtering, which solves the contradiction between the quick-break precision of current with delay and time, effectively improves the judgment precision, and is suitable for being used in places with higher requirements on the quick-break precision of current.
Description
Technical Field
The invention relates to a method for improving the quick-break precision of a time-limited current based on mean value filtering.
Background
The mechanism of delayed current quick break is generally used in comprehensive protection equipment in high-low voltage complete equipment (high-low voltage power distribution cabinet), the comprehensive protection equipment is mainly used for controlling and protecting a power system (including users such as power plants, substations, power transmission and distribution lines, industrial and mining enterprises and the like), a user can put a part of power equipment or lines into or out of operation according to the operation requirements of a power grid, and the function of timely and quickly cutting off a fault part from the power grid when the power equipment or lines have faults can be realized. The whole process comprises the steps of collecting voltage and current from high-voltage electricity, carrying out secondary transformation ratio through a mutual inductor, calculating a true effective value by using secondary data, and carrying out fault judgment by using the true effective value as a judgment basis. The precision of +/-0.5% can be basically maintained in the true effective value error industry obtained through the steps.
In the whole comprehensive protection system, three-section current protection is very important, the protection also needs to meet the requirements of sensitivity, quick action and selectivity and reliability, but the indexes cannot be obtained at the same time, and all three-section protection currents are generated. One section of the circuit is called as current quick-break protection, the protection has no time limit, the second section is called as time-limit current quick-break according to the setting of avoiding the maximum short-circuit current at the tail end of the section, and the setting is carried out according to the maximum action range of avoiding the current quick-break protection of each adjacent element at the next stage, so that the circuit can be used as backup protection for one section of the circuit, and the time limit is more than one section. The second section can not protect the whole length in order to make up for the first section, so the protection range of the second section is extended to the next section of line, but the next section of line cannot jump firstly when in fault, so a delay is added, the range does not exceed the current quick break of the next section of line, the condition that the tail end of the line is in fault, the second section of line trips after delay is formed, and the fault of the quick break range of the next section of line directly jumps from the zero time limit of the quick break of the next section of line is met, so that the first section of line can jump by the protection action of the first section of line, and the adjacent next section of line cannot be influenced. The third segment is actually a backup protection added to prevent the two segments from being refused, and the time is longer and the range is larger.
In the whole time-limited current quick-break, the current is continuously judged in the whole time-limited time range, if the current is not judged to be processed by the previous-stage protection, the current timing value is cleared, the normal operation is continued, and if the large current is detected again, the judgment of the time-limited current quick-break is continued. As described above, since the true effective value error of the basis is maintained at ± 0.5%, the time-limited quick-break protection is disabled in this case by setting the setting value to 10A, for example, to be 9.95A to 10.05A, and by setting the setting value to 10A, the data of less than 10A is available.
Disclosure of Invention
The invention aims to provide a method for improving the accuracy of the quick break of the current with time limit based on mean value filtering, which solves the contradiction between the accuracy and the time of the quick break of the current with time delay and effectively improves the accuracy of the judgment.
A method for improving the accuracy of quick break of a time-limited current based on mean value filtering is characterized by comprising the following steps:
(1) multiplying the real effective value subjected to time-limited quick-break to make the real effective value larger than 2 thousandths;
(2) and converting the judgment basis after the time-limited quick-break protection into the true effective value data after mean value filtering every ten true effective values.
Further:
(1) judging time-limited quick-break protection by taking 5ms as a timing period, using a time-limited quick-break protection judgment algorithm, firstly judging a time-limited quick-break protection timing zone bit, if the timer zone bit is started, judging whether 10 data to be averaged are full of storage, if the 10 data to be averaged are full of storage, clearing a mean counting bit and clearing the mean, and then carrying out mean algorithm processing on the 10 full of storage data; if the 10 true effective values are not stored, storing the 10 true effective values into 1.002 times of the current effective value, and then adding 1 to the average count value; if the time-limited quick-break protection timing flag bit is not opened, the true effective value is expanded to 1.002 times and then is assigned to the mean value;
(2) judging whether overcurrent two-stage protection is put into use, if so, continuing to execute a time-limit quick-break protection judgment algorithm based on mean value filtering, and if the mean value is greater than or equal to a setting value, marking the position 1 of a time-limit quick-break timer, and starting the time-limit quick-break timer to start timing; judging whether the count of the two-stage protection timing reaches a setting value, if so, exiting the time-limited quick-break protection pressing plate, executing the protection action of time-limited quick-break current, sending corresponding fault information to an upper computer for displaying, if not, exiting the algorithm, namely, waiting for the next execution of the algorithm based on the time-limited quick-break protection judgment algorithm of mean value filtering, and if the mean value is smaller than the setting value, exiting the time-limited quick-break protection algorithm for waiting for the next execution of the algorithm.
The invention provides a method for improving the quick-break precision of current with delay based on mean value filtering, which solves the contradiction between the quick-break precision of current with delay and time, effectively improves the judgment precision, and is suitable for being used in places with higher requirements on the quick-break precision of current. The beneficial effects of the invention also include: 1. the failure of current time-limited quick-break protection caused by the condition that the setting value and the current value are equal can be effectively avoided. 2. The algorithm does not affect the precision of the whole delay time under the condition of ensuring the current precision effect. 3. The method has low complexity and is easy to realize.
Drawings
FIG. 1 is a flow chart of time-limited quick-break protection with mean value;
the upper diagram of fig. 2 is a flow chart of the averaging process.
Detailed Description
The invention provides a method for improving the accuracy of quick break of a time-limited current based on mean value filtering, which comprises the following steps:
(3) multiplying the real effective value subjected to time-limited quick-break to make the real effective value larger than 2 thousandths;
(4) and converting the judgment basis after the time-limited quick-break protection into the true effective value data after mean value filtering every ten true effective values.
Further:
(1) taking 5ms as a timing period, judging time-limited quick-break protection, and entering a time-limited quick-break protection judgment algorithm, namely considering the whole length of the line to be protected, wherein the protection range of the line is inevitably extended to the next line, so that the line is started when a short circuit occurs at the outlet of the next line; in this case, to ensure the selectivity of the action, it is necessary to have a certain time limit for the action of the protection, the size of which is related to the range over which it extends. In order to shorten this time limit as much as possible, generally, first, the protection range is considered to be not beyond the range of the next line quick-break protection, and the action time limit is higher than the quick-break protection of the next line by a time period Δ t, first, a time-limited quick-break protection timing flag bit is judged, if the timer flag bit is turned on, whether 10 data to be averaged are full is judged, if the 10 data to be averaged are full, the average counting bit is cleared, and the average is cleared, then the full 10 data are subjected to an average algorithm, the algorithm is a quantity representing the trend in a group of data set, and means that the sum of all data in a group of data is divided by the quantity of the group of data. It is an index that reflects the trend in the data set. The key of solving the application problem of the average number is to determine the total number and the total number corresponding to the total number for processing; if the number of the true effective values is not full of 10, storing the true effective values into 1.002 times of the current effective values, establishing a buffer area (0-9) with the size capable of storing 10 true effective values, when the average value count value is 0, placing the true effective values into the area of the buffer area 0, when the average value count value is 9, placing the true effective values into the area of the buffer area 9, and then adding 1 to the average value count value; if the time-limited quick-break protection timing flag bit is not opened, the true effective value is expanded to 1.002 times and then is assigned to the mean value;
(2) judging whether overcurrent two-stage protection is put into use, if so, continuing to execute a time-limit quick-break protection judgment algorithm based on mean value filtering, and if the mean value is greater than or equal to a setting value, marking the position 1 of a time-limit quick-break timer, and starting the time-limit quick-break timer to start timing; judging whether the count of the two-stage protection timing reaches a setting value, if so, exiting the time-limited quick-break protection pressing plate, executing the protection action of time-limited quick-break current, sending corresponding fault information to an upper computer for displaying, if not, exiting the algorithm, namely, waiting for the next execution of the algorithm based on the time-limited quick-break protection judgment algorithm of mean value filtering, and if the mean value is smaller than the setting value, exiting the time-limited quick-break protection algorithm for waiting for the next execution of the algorithm.
Example 1:
the invention provides a method for solving the problem that the lower limit quick-break protection fails due to the precision problem under the condition described in the background technology, and the time limit quick-break protection can be accurately and timely carried out under the condition. Generally, each time the detection is performed (generally, the detection is performed in a period of 5 ms), the value is enlarged to 1.002 times of the original value at the time of judgment, and once the time-limited quick-break protection is performed, the subsequent judgment is calculated by averaging ten values, so that the number of current values larger than 10A is substantially always larger than the number of current values smaller than 10A. This effectively avoids the problem of snap-down failure at this lower limit due to a value below 10A.
The method comprises the following steps:
1. amplifying the real effective value subjected to time-limited quick-break according to magnification, so that the whole real effective value is larger than 2 thousandths;
2. and (4) after entering time-limited quick-break protection, converting the true effective value into data subjected to mean value filtering every ten times.
The method of the invention takes 5ms as a timing period to judge the time-limited quick-break protection, after entering a judgment algorithm of the time-limited quick-break protection, firstly judging a time-limited quick-break protection timing zone bit, if the timer zone bit is opened, judging whether 10 data to be averaged are full, if the 10 data to be averaged are full, clearing an average counting bit, clearing the average, and then carrying out average algorithm processing on the 10 full data. If the 10 true effective values are not stored, the current effective value is stored by 1.002 times, and the average count value is increased by 1. If the time-limited quick-break protection timing flag bit is not turned on, the two-stage overcurrent protection is not triggered, the true effective value is expanded to 1.002 times and then assigned to the mean value.
Judging whether overcurrent two-stage protection is put into use, if so, continuing to execute the protection, if the mean value is more than or equal to a setting value, marking the position 1 of a time-limited quick-break timer, starting the time-limited quick-break timer to start timing, judging whether the count of the two-stage protection timing reaches the setting value, if so, exiting the time-limited quick-break protection pressing plate, executing the protection action of time-limited quick-break current, and sending corresponding fault information to display by an upper computer. And if the time does not reach the setting value, exiting the algorithm to wait for the next execution of the algorithm. And if the average value is smaller than the setting value, exiting the time-limited quick-break protection algorithm to wait for the next execution of the algorithm.
The specific implementation steps of the method are described in a specific implementation, and the step-by-step description of the method is performed by setting a given current 10A, a current setting value to 10A and a time setting value to 10 s.
Given a current of 10A, we obtained 10 calculated values from the true effective value as shown below.
The ten calculated values expanded to 1.002 times are shown in the following table:
after the value is substituted into the above-mentioned inventive content, the flow in the figure can be obtained.
The true effective value 10.05006 in the sequence number 1 is greater than the overcurrent two-stage protection setting value, the starting of continuous counting is carried out, the table after the average value is solved is shown in the upper table, the value of 10.022 is used as the judgment basis of the time-limited quick-break to trigger the time-limited quick-break, and the time-limited quick-break can be known from the attached drawings to be continuously effective and can not be caused by the occurrence of data below the setting value to cause the failure of the time-limited quick-break.
Claims (1)
1. A method for improving the accuracy of quick break of a time-limited current based on mean value filtering is characterized by comprising the following steps:
(1) multiplying the real effective value subjected to time-limited quick-break to make the real effective value larger than 2 thousandths;
(2) converting the judgment basis after entering time-limited quick-break protection from the true effective value into the true effective value data after every ten true effective values are subjected to mean value filtering;
the method comprises the following steps:
1) judging time-limited quick-break protection by taking 5ms as a timing period, using a time-limited quick-break protection judgment algorithm, firstly judging a time-limited quick-break protection timing zone bit, if the timer zone bit is started, judging whether 10 data to be averaged are full of storage, if the 10 data to be averaged are full of storage, clearing a mean counting bit and clearing the mean, and then carrying out mean algorithm processing on the 10 full of storage data; if the 10 true effective values are not stored, storing the 10 true effective values into 1.002 times of the current effective value, and then adding 1 to the average count value; if the time-limited quick-break protection timing flag bit is not opened, the true effective value is expanded to 1.002 times and then is assigned to the mean value;
2) judging whether overcurrent two-stage protection is put into use, if so, continuing to execute a time-limit quick-break protection judgment algorithm based on mean value filtering, and if the mean value is greater than or equal to a setting value, marking the position 1 of a time-limit quick-break timer, and starting the time-limit quick-break timer to start timing; judging whether the count of the two-stage protection timing reaches a setting value, if so, exiting the time-limited quick-break protection pressing plate, executing the protection action of time-limited quick-break current, sending corresponding fault information to an upper computer for displaying, if not, exiting the algorithm, namely, waiting for the next execution of the algorithm based on the time-limited quick-break protection judgment algorithm of mean value filtering, and if the mean value is smaller than the setting value, exiting the time-limited quick-break protection algorithm for waiting for the next execution of the algorithm.
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| CN100418281C (en) * | 2006-10-16 | 2008-09-10 | 黑龙江大学 | Method for realizing self adaptive current quick break protection of power supply circuit |
| US8433743B2 (en) * | 2008-10-29 | 2013-04-30 | Maxim Intergrated Products, Inc. | Root mean square (RMS) metering devices and methods for generating RMS current level to both high or low frequency within signal |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103580007A (en) * | 2012-07-25 | 2014-02-12 | 江苏创能电器有限公司 | Intelligent frame controller |
| CN103311911A (en) * | 2013-07-11 | 2013-09-18 | 中国船舶重工集团公司第七0四研究所 | Network type differential protection device for boat and differential protection output determining method |
| CN105958500A (en) * | 2016-06-17 | 2016-09-21 | 国网江苏省电力公司电力科学研究院 | Flexible load autonomous controller capable of sensing power network voltage reduction and control method of controller |
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