CN110927627A - Monitoring method for measuring winding wire breakage and three-phase current unbalanced operation by CT - Google Patents
Monitoring method for measuring winding wire breakage and three-phase current unbalanced operation by CT Download PDFInfo
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- CN110927627A CN110927627A CN201911106739.XA CN201911106739A CN110927627A CN 110927627 A CN110927627 A CN 110927627A CN 201911106739 A CN201911106739 A CN 201911106739A CN 110927627 A CN110927627 A CN 110927627A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
- G01R19/16571—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/16—Measuring asymmetry of polyphase networks
Abstract
The invention discloses a monitoring method for measuring winding wire break and three-phase current unbalanced operation by CT, which comprises the following steps: (1) a monitoring program for CT current disconnection and three-phase unbalance is added in the dispatching automation system; (2) judging the starting conditions of the CT current disconnection and three-phase unbalance judging program, and starting the corresponding judging program; (3) if the starting conditions of the CT current disconnection and three-phase unbalance judging program are met, judging whether the following alarm logic judging conditions are met, and if the corresponding alarm logic judging conditions are met, sending out a CT current disconnection alarm or a CT current unbalance alarm; the abnormal operation state of the power equipment can be immediately found by a regulation and control attendant through a CT current disconnection alarm or a CT current imbalance alarm sent by a dispatching automation system, the monitoring of the CT measurement winding disconnection and the three-phase current imbalance operation is realized, and the monitoring is convenient.
Description
Technical Field
The invention belongs to the field of power grid dispatching automation, and particularly relates to a monitoring method for measuring winding disconnection and three-phase current unbalanced operation by CT.
Background
According to the use of the secondary equipment CT, the CT can be classified into three types, namely CT for measurement, CT for protection and CT for metering. The peak is described in an article entitled "discussion about increasing the function of detecting CT disconnection of measuring device": when the CT is disconnected, the following consequences can occur: (1) due to the saturation of the magnetic flux, the secondary side of the magnetic flux generates thousands of volts of high voltage, and the waveform changes, causing damage to operators and equipment. (2) Because the magnetic flux of the iron core is saturated, the loss of the iron core is increased, high heat is generated, and insulation is damaged. Therefore, the CT disconnection detection alarm function is necessary to be added in the secondary loop. At present, only the protection device is provided with a CT disconnection detection alarm function, and the metering loop is not allowed to have a joint, namely, the possibility of open circuit of the secondary loop is avoided. At present, the domestic measuring device has no CT secondary circuit disconnection detection alarm function, and the protection, measurement and control integrated device can only reflect the CT secondary disconnection fault for protection. When the CT secondary circuit for measurement is broken, the protection device and the measurement and control device have no detection and alarm functions. The measurement and control device is additionally provided with a CT secondary measurement loop disconnection alarm, the CT secondary measurement loop disconnection judgment logic outputs a result, and the remote signaling loop sends an alarm signal.
The Chinese patent with application number 200710013701.9 discloses a method for detecting CT disconnection and short circuit, which introduces the current for protecting CT and the current for measuring CT into a protection device integrating measurement and control, wherein under normal conditions, the currents of the CT and the CT are the same, if the currents of the CT and the CT are different, the CT disconnection and short circuit fault is considered to occur, and the CT is locked for protection or is alarmed after time delay confirmation.
The current research mainly focuses on the research of detecting the CT disconnection of the measuring and controlling device of the transformer substation, and the monitoring of the unbalance of the three-phase current of the power equipment is not realized. When three-phase unbalanced operation of primary power equipment and disconnection of a CT measurement winding occur in an electric power system, the monitoring function of the measurement and control device is not provided, and alarm information cannot be sent out in time, so that disconnection of the CT measurement winding and unbalanced operation state of the electric power equipment cannot be found immediately through a manual mode in a dispatching automation system. Therefore, the damage caused by the long-time three-phase unbalanced operation of the power equipment and the secondary open circuit of the CT measurement winding cannot be eliminated in time. If a measurement and control device is adopted to monitor the CT measurement winding disconnection, all the measurement and control devices are required to be subjected to program modification or device replacement, and power failure of primary power equipment is required if necessary, so that the device is wide in multiple ranges, and much manpower and material resources are required.
Disclosure of Invention
The invention aims to provide a method for monitoring the disconnection of a CT measurement winding and the unbalanced operation of three-phase current, aiming at solving the problem that the existing CT current disconnection or the problem that the three-phase unbalanced operation of power equipment and the secondary open-circuit operation of the CT measurement winding cannot be found immediately in a manual mode when the CT current unbalance occurs. According to the method, a control attendant can immediately find the abnormal operation state of the power equipment through a CT current disconnection alarm or a CT current imbalance alarm sent by a dispatching automation system.
The scheme of the invention is realized by the following steps:
a monitoring method for CT measurement of winding wire break and three-phase current unbalanced operation comprises the following steps:
the method comprises the following steps that (1) a monitoring program of CT current disconnection and three-phase unbalance is added to a dispatching automation system;
the logic for judging the start of the monitoring program is as follows: firstly, judging the switch position of the interval of the primary equipment, if the switch is in the opening position, not starting the monitoring program, if the switch is in the closing position, starting the monitoring program, starting to compare the three-phase current values Ia, Ib and Ic, and respectively taking the minimum value Imin and the maximum value Imax;
step (2) judging the starting conditions of the CT current disconnection and three-phase unbalance judging program, and starting the corresponding judging program;
when Imin =0, starting a CT current disconnection judging program;
when Imin is greater than 0, starting a CT current imbalance judging program;
if the starting conditions of the CT current disconnection and three-phase unbalance judging program are met, judging whether the following alarm logic judging conditions are met, and if the corresponding alarm logic judging conditions are met, sending out a CT current disconnection alarm or a CT current unbalance alarm;
the CT current disconnection warning logic judgment condition is as follows: when Imax is reached>0, and passes T1If the logic is still satisfied after the time, a CT current disconnection alarm is sent;
the CT current imbalance alarm logic judgment condition is as follows: when Imin > Im and (Imax-Imin)/Imin x 100% > M, and T passes2If the logic is still satisfied after the time, a CT current imbalance alarm is sent out;
wherein, T1、T2Is a manually set delay time; im is a manually set current threshold; m is a manually set current imbalance threshold value;
the regulation and control operator can immediately find the abnormal operation state of the power equipment through the CT current disconnection warning or the CT current imbalance warning sent by the dispatching automation system, and the monitoring of the CT measurement winding disconnection and the three-phase current imbalance operation is realized.
As a further explanation of the invention, the manually set current threshold value is 8-12A.
As a further explanation of the invention, the manually set current imbalance threshold is set to 40-60%.
As a further explanation of the present invention, the manually set delay time T1Is 4-6 s.
As a further explanation of the present invention, the manually set delay time T2Is 4-6 s.
The invention has the following good effects:
1. the invention realizes that the abnormal operation state of the power equipment can be immediately found by the CT current disconnection alarm or the CT current imbalance alarm sent by the dispatching automation system by the regulating attendant, and solves the problems that the three-phase unbalanced operation of the power equipment and the secondary open circuit operation of the CT measuring winding cannot be immediately found by a manual mode.
2. The technology of the invention is easy to realize, only a monitoring program needs to be deployed in a data processing server of the dispatching automation system, and more manpower and material resources do not need to be spent.
Detailed Description
The following describes a method for monitoring the operation of a CT apparatus for measuring winding breakage and three-phase current imbalance according to the present invention with reference to the following embodiments, which are not intended to limit the present invention in any way.
Example 1:
a monitoring method for CT measurement of winding wire break and three-phase current unbalanced operation comprises the following steps:
the method comprises the following steps that (1) a monitoring program of CT current disconnection and three-phase unbalance is added to a dispatching automation system;
the logic for judging the start of the monitoring program is as follows: firstly, judging the switch position of the interval of the primary equipment, if the switch is in the opening position, not starting the monitoring program, if the switch is in the closing position, starting the monitoring program, starting to compare the three-phase current values Ia, Ib and Ic, and respectively taking the minimum value Imin and the maximum value Imax;
step (2) judging the starting conditions of the CT current disconnection and three-phase unbalance judging program, and starting the corresponding judging program;
when Imin =0, starting a CT current disconnection judging program;
when Imin is greater than 0, starting a CT current imbalance judging program;
if the starting conditions of the CT current disconnection and three-phase unbalance judging program are met, judging whether the following alarm logic judging conditions are met, and if the corresponding alarm logic judging conditions are met, sending out a CT current disconnection alarm or a CT current unbalance alarm;
the CT current disconnection warning logic judgment condition is as follows: when Imax is greater than 0 and logic is still met after 4s of time, a CT current disconnection alarm is sent out;
the CT current imbalance alarm logic judgment condition is as follows: when Imin is more than 8A and (Imax-Imin)/Imin multiplied by 100% is more than 40%, and logic is still met after 4s of time, a CT current imbalance alarm is sent out;
wherein, T1 and T2 are delay time set manually; im is a manually set current threshold; m is a manually set current imbalance threshold value;
the regulation and control operator can immediately find the abnormal operation state of the power equipment through the CT current disconnection warning or the CT current imbalance warning sent by the dispatching automation system, and the monitoring of the CT measurement winding disconnection and the three-phase current imbalance operation is realized.
Example 2:
a monitoring method for CT measurement of winding wire break and three-phase current unbalanced operation comprises the following steps:
the method comprises the following steps that (1) a monitoring program of CT current disconnection and three-phase unbalance is added to a dispatching automation system;
the logic for judging the start of the monitoring program is as follows: firstly, judging the switch position of the interval of the primary equipment, if the switch is in the opening position, not starting the monitoring program, if the switch is in the closing position, starting the monitoring program, starting to compare the three-phase current values Ia, Ib and Ic, and respectively taking the minimum value Imin and the maximum value Imax;
step (2) judging the starting conditions of the CT current disconnection and three-phase unbalance judging program, and starting the corresponding judging program;
when Imin =0, starting a CT current disconnection judging program;
when Imin is greater than 0, starting a CT current imbalance judging program;
if the starting conditions of the CT current disconnection and three-phase unbalance judging program are met, judging whether the following alarm logic judging conditions are met, and if the corresponding alarm logic judging conditions are met, sending out a CT current disconnection alarm or a CT current unbalance alarm;
the CT current disconnection warning logic judgment condition is as follows: when Imax is greater than 0 and the logic is still met after 5s of time, a CT current disconnection alarm is sent out;
the CT current imbalance alarm logic judgment condition is as follows: when Imin is more than 10A and (Imax-Imin)/Imin multiplied by 100% is more than 50%, and the logic is still satisfied after 5s, a CT current imbalance alarm is sent out;
wherein, T1、T2Is a manually set delay time; im is a manually set current threshold; m is a manually set current imbalance threshold value;
the regulation and control operator can immediately find the abnormal operation state of the power equipment through the CT current disconnection warning or the CT current imbalance warning sent by the dispatching automation system, and the monitoring of the CT measurement winding disconnection and the three-phase current imbalance operation is realized.
Example 3:
a monitoring method for CT measurement of winding wire break and three-phase current unbalanced operation comprises the following steps:
the method comprises the following steps that (1) a monitoring program of CT current disconnection and three-phase unbalance is added to a dispatching automation system;
the logic for judging the start of the monitoring program is as follows: firstly, judging the switch position of the interval of the primary equipment, if the switch is in the opening position, not starting the monitoring program, if the switch is in the closing position, starting the monitoring program, starting to compare the three-phase current values Ia, Ib and Ic, and respectively taking the minimum value Imin and the maximum value Imax;
step (2) judging the starting conditions of the CT current disconnection and three-phase unbalance judging program, and starting the corresponding judging program;
when Imin =0, starting a CT current disconnection judging program;
when Imin is greater than 0, starting a CT current imbalance judging program;
if the starting conditions of the CT current disconnection and three-phase unbalance judging program are met, judging whether the following alarm logic judging conditions are met, and if the corresponding alarm logic judging conditions are met, sending out a CT current disconnection alarm or a CT current unbalance alarm;
the CT current disconnection warning logic judgment condition is as follows: when Imax is greater than 0 and the logic is still met after 6s, a CT current disconnection alarm is sent out;
the CT current imbalance alarm logic judgment condition is as follows: when Imin is greater than 12A and (Imax-Imin)/Imin multiplied by 100% is greater than 60%, and logic is still met after 6s, a CT current imbalance alarm is sent out;
wherein, T1、T2Is a manually set delay time; im is a manually set current threshold; m is a manually set current imbalance threshold value;
the regulation and control operator can immediately find the abnormal operation state of the power equipment through the CT current disconnection warning or the CT current imbalance warning sent by the dispatching automation system, and the monitoring of the CT measurement winding disconnection and the three-phase current imbalance operation is realized.
The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.
Claims (5)
1. A monitoring method for CT measurement of winding wire breakage and three-phase current unbalanced operation is characterized by comprising the following steps:
the method comprises the following steps that (1) a monitoring program of CT current disconnection and three-phase unbalance is added to a dispatching automation system;
the logic for judging the start of the monitoring program is as follows: firstly, judging the switch position of the interval of the primary equipment, if the switch is in the opening position, not starting the monitoring program, if the switch is in the closing position, starting the monitoring program, starting to compare the three-phase current values Ia, Ib and Ic, and respectively taking the minimum value Imin and the maximum value Imax;
step (2) judging the starting conditions of the CT current disconnection and three-phase unbalance judging program, and starting the corresponding judging program;
when Imin =0, starting a CT current disconnection judging program;
when Imin is greater than 0, starting a CT current imbalance judging program;
if the starting conditions of the CT current disconnection and three-phase unbalance judging program are met, judging whether the following alarm logic judging conditions are met, and if the corresponding alarm logic judging conditions are met, sending out a CT current disconnection alarm or a CT current unbalance alarm;
the CT current disconnection warning logic judgment condition is as follows: when Imax is reached>0, and passes T1If the logic is still satisfied after the time, a CT current disconnection alarm is sent;
the CT current imbalance alarm logic judgment condition is as follows: when Imin > Im and (Imax-Imin)/Imin x 100% > M, and T passes2If the logic is still satisfied after the time, a CT current imbalance alarm is sent out;
wherein, T1、T2Is a manually set delay time; im is a manually set current threshold; m is a manually set current imbalance threshold value;
the regulation and control operator can immediately find the abnormal operation state of the power equipment through the CT current disconnection warning or the CT current imbalance warning sent by the dispatching automation system, and the monitoring of the CT measurement winding disconnection and the three-phase current imbalance operation is realized.
2. The method for monitoring the CT measurement of winding breakage and three-phase current unbalance operation according to claim 1, wherein the manually set current threshold value Im is 8-12A.
3. The method for monitoring CT measurement of winding breakage and three-phase current unbalance operation as claimed in claim 1, wherein the manually set current unbalance threshold value M is set to 40-60%.
4. The method as claimed in claim 1, wherein the time delay T is set manually1Is 4-6 s.
5. The method as claimed in claim 1, wherein the time delay T is set manually2Is 4-6 s.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112098898A (en) * | 2020-09-22 | 2020-12-18 | 国网四川省电力公司眉山供电公司 | Disconnection fault judgment method and device and regulation and control system |
| CN114034923A (en) * | 2021-10-29 | 2022-02-11 | 无锡皓凯利科技有限公司 | Automatic measurement winding broken string and three-phase active power synchrophasor precision leveling system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112098898A (en) * | 2020-09-22 | 2020-12-18 | 国网四川省电力公司眉山供电公司 | Disconnection fault judgment method and device and regulation and control system |
| CN114034923A (en) * | 2021-10-29 | 2022-02-11 | 无锡皓凯利科技有限公司 | Automatic measurement winding broken string and three-phase active power synchrophasor precision leveling system |
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Application publication date: 20200327 |