CN111987699B - Current differential protection data synchronization method of alternating current line and related device - Google Patents
Current differential protection data synchronization method of alternating current line and related device Download PDFInfo
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- CN111987699B CN111987699B CN202010831519.XA CN202010831519A CN111987699B CN 111987699 B CN111987699 B CN 111987699B CN 202010831519 A CN202010831519 A CN 202010831519A CN 111987699 B CN111987699 B CN 111987699B
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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
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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
- G01R19/02—Measuring effective values, i.e. root-mean-square values
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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
- G01R19/10—Measuring sum, difference or ratio
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
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- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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Abstract
The application discloses a current differential protection data synchronization method and a related device of an alternating current line, wherein the method comprises the following steps: firstly, judging a fault phase of a three-phase line according to the starting condition of a starting element; then, calculating the voltage change condition of the receiving end by using the voltage measured by the transmitting end of the fault phase and related line parameters, namely calculating the voltage; and finally, waveform matching can be carried out between the target measurement voltage before and after the starting of the receiving-end starting element and the calculated voltage, and the sampling time error between the alternating-current lines on the two sides, namely the time error, can be obtained according to the maximum value of the waveform similarity obtained by calculation. Therefore, the method and the device solve the technical problem that channel multiplexing in the existing channel-based data synchronization technology easily causes delay inconsistency of receiving and sending channels, so that current differential protection is subjected to misoperation.
Description
Technical Field
The present disclosure relates to the field of relay protection technologies, and in particular, to a method and a related apparatus for synchronizing current differential protection data of an ac line.
Background
The current differential protection principle of the alternating current circuit is simple, the action speed is high, the sensitivity is high, and the alternating current circuit has natural phase selection capability and is not influenced by system oscillation. With the development of power system communication networks, line current differential protection has gradually become a main protection mode of main protection of high-voltage transmission lines. The line current differential protection algorithmically requires that the current quantities on two sides which participate in comparison must be synchronously sampled or obtained by sampling synchronization processing, which is the key point for realizing the current differential protection. If the current amounts on the two sides of the alternating current line are not synchronous, the current differential protection is caused to malfunction when an external fault occurs.
Currently, data synchronization methods applied in practice are all based on data channels, but with the continuous development of power communication networks, SDH multiplexing channels are commonly applied, which causes that the delays of receiving and transmitting channels are likely to be inconsistent, so that some current channel-based data synchronization methods are not applicable any more.
Disclosure of Invention
The application provides a current differential protection data synchronization method and a related device of an alternating current circuit, which are used for solving the technical problem that channel multiplexing in the existing channel-based data synchronization technology easily causes delay inconsistency of receiving and sending channels, so that current differential protection is subjected to misoperation.
In view of the above, a first aspect of the present application provides a method for synchronizing current differential protection data of an ac line, including:
when the AC line has a fault, respectively calculating the difference of the effective values of the measured voltages of the three-phase line before and after the starting of the starting element, and selecting the maximum phase corresponding to the maximum value of the difference of the effective values of the measured voltages;
calculating the calculated voltage of a preset time period before and after the starting of the starting element at the maximum corresponding protected installation position of the receiving end according to the line parameters, the measured voltage of the transmitting end and the measured current of the transmitting end, wherein the calculated voltage comprises a calculation starting time and a calculation ending time;
selecting a matching time period according to the starting time of a receiving end starting element, wherein the matching time period comprises a matching starting time and a matching ending time;
taking the matching starting time as the measurement starting time of the receiving end measurement voltage, and selecting the target measurement voltage of the preset time period from the receiving end measurement voltage, wherein the target measurement voltage comprises the measurement starting time and the measurement ending time;
calculating waveform similarity between the target measurement voltage and the calculated voltage;
if the measurement starting time is smaller than the starting time and the measurement ending time is smaller than the matching ending time, moving the matching starting time backwards by a preset sampling interval, returning to the step of taking the matching starting time as the measurement starting time of the voltage measured by the receiving end, otherwise, judging whether the maximum waveform similarity is smaller than a similarity threshold value, if so, obtaining a null value result, and if not, subtracting the measurement starting time corresponding to the maximum waveform similarity from the calculation starting time to obtain a time error between the sending end alternating current line and the receiving end alternating current line;
and carrying out synchronous adjustment on the current differential protection data according to the time error.
Optionally, when the ac line fails, the method further includes the steps of calculating a difference between effective values of measured voltages of the three-phase line before and after the starting of the starting element, respectively:
when the AC line has a fault, transmitting the transmitting end measured voltage and the transmitting end current instantaneous value to a receiving end protection device;
correspondingly, when the alternating current line has a fault, the instantaneous values of the receiving-end measured voltage and the receiving-end current are sent to the sending-end protection device.
Optionally, when the ac line fails, respectively calculating a difference between effective values of measured voltages of the three-phase line before and after the starting of the starting element, and selecting a maximum phase corresponding to a maximum value of the difference between the effective values of the measured voltages, includes:
when the AC line has a fault, the difference between the effective values of the measured voltages of the three-phase line in the half cycle before the start of the starting element and the half cycle after the start of the starting element is calculated respectively, and the maximum phase corresponding to the maximum value of the difference of the effective values of the measured voltages is selected.
Optionally, the selecting a matching time period according to the starting time of the receiving-end starting element, where the matching time period includes a matching starting time and a matching terminating time, includes:
selecting a preset time before the starting time of the receiving end starting element as a matching starting time;
and selecting a preset time after the starting time of the receiving end starting element as the matching termination time.
A second aspect of the present application provides a current differential protection data synchronization apparatus for an ac line, including:
the first calculation module is used for respectively calculating the difference of the effective values of the measured voltages of the three-phase line before and after the starting element is started when the alternating-current line has a fault, and selecting the maximum phase corresponding to the maximum value of the difference of the effective values of the measured voltages;
the second calculation module is used for calculating the calculation voltage of the preset time period before and after the starting of the starting element at the maximum corresponding protected installation position of the receiving end according to the line parameters, the measured voltage of the sending end and the measured current of the sending end, wherein the calculation voltage comprises the calculation starting time and the calculation stopping time;
the device comprises a first selection module, a second selection module and a third selection module, wherein the first selection module is used for selecting a matching time period according to the starting time of a receiving end starting element, and the matching time period comprises a matching starting time and a matching ending time;
a second selection module, configured to use the matching start time as a measurement start time of a receiving-end measurement voltage, and select a target measurement voltage of the preset time period from the receiving-end measurement voltage, where the target measurement voltage includes the measurement start time and a measurement termination time;
the third calculation module is used for calculating the waveform similarity between the target measurement voltage and the calculated voltage;
a judging module, configured to move the matching start time backward by a preset sampling interval if the measurement start time is less than the start time and the measurement end time is less than the matching end time, and trigger the second selecting module, otherwise, judge whether a maximum waveform similarity is less than a similarity threshold, if yes, obtain a null result, and if not, difference the measurement start time corresponding to the maximum waveform similarity with the calculation start time, and obtain a time error between the sending-end ac line and the receiving-end ac line;
and the synchronization module is used for carrying out current differential protection data synchronization adjustment according to the time error.
Optionally, the method further includes:
the data transmission module is used for transmitting the transmitting end measured voltage and the transmitting end current instantaneous value to the receiving end protection device when the alternating current circuit fails;
correspondingly, when the alternating current line has a fault, the instantaneous values of the receiving-end measured voltage and the receiving-end current are sent to the sending-end protection device.
Optionally, the first selecting module is specifically configured to:
selecting a preset time before the starting time of the receiving end starting element as a matching starting time;
and selecting a preset time after the starting time of the receiving end starting element as the matching termination time.
A third aspect of the present application provides an ac line current differential protection data synchronization system, including: the system comprises a transmitting end equivalent power supply, a receiving end equivalent power supply, a first bus, a second bus, a transmitting end relay protection device, a receiving end relay protection device and an ABC three-phase alternating-current line;
a first terminal of the ABC three-phase alternating-current line is connected with the sending end equivalent power supply through the first bus, and a second terminal of the ABC three-phase alternating-current line is connected with the sending end equivalent power supply through the second bus;
the sending end relay protection device is arranged on the ABC three-phase alternating-current circuit connected with the first bus;
and the receiving end relay protection device is arranged on the ABC three-phase alternating-current circuit connected with the second bus.
A fourth aspect of the present application provides an apparatus for current differential protection data synchronization of an ac line, the apparatus comprising a processor and a memory:
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is configured to execute the method for current differential protection data synchronization of an ac line according to the first aspect according to instructions in the program code.
A fifth aspect of the present application provides a computer-readable storage medium for storing program code for executing the method for current differential protection data synchronization of an ac line according to the first aspect.
According to the technical scheme, the embodiment of the application has the following advantages:
the present application provides a method for synchronizing current differential protection data of an ac line, including: when the AC line has a fault, respectively calculating the difference of the effective values of the measured voltages of the three-phase line before and after the starting element is started, and selecting the maximum phase corresponding to the maximum value of the difference of the effective values of the measured voltages; calculating the maximum corresponding calculated voltage of a preset time period before and after the starting of the starting element at the protected installation part of the receiving end according to the line parameters, the measured voltage of the transmitting end and the measured current of the transmitting end, wherein the calculated voltage comprises the calculation starting time and the calculation ending time; selecting a matching time period according to the starting time of the receiving end starting element, wherein the matching time period comprises a matching starting time and a matching ending time; taking the matched starting time as the measurement starting time of the receiving end measurement voltage, and selecting a target measurement voltage of a preset time period from the receiving end measurement voltage, wherein the target measurement voltage comprises the measurement starting time and the measurement ending time; calculating the waveform similarity between the target measurement voltage and the calculated voltage; if the measurement starting time is less than the starting time and the measurement ending time is less than the matching ending time, moving the matching starting time backwards by a preset sampling interval, returning to the step of taking the matching starting time as the measurement starting time of the voltage measured by the receiving end, otherwise, judging whether the maximum waveform similarity is less than a similarity threshold value, if so, obtaining a null value result, and if not, subtracting the measurement starting time corresponding to the maximum waveform similarity from the calculation starting time to obtain a time error between the sending end alternating current circuit and the receiving end alternating current circuit; and carrying out synchronous adjustment on the current differential protection data according to the time error.
According to the current differential protection data synchronization method of the alternating current circuit, firstly, the fault phase of the three-phase circuit is judged according to the starting condition of a starting element; then, calculating the voltage change condition of the receiving end by using the voltage measured by the transmitting end of the fault phase and related line parameters, namely calculating the voltage; and finally, waveform matching can be carried out between the target measurement voltage before and after the starting of the receiving-end starting element and the calculated voltage, and the sampling time error between the alternating-current lines on the two sides, namely the time error, can be obtained according to the maximum value of the waveform similarity obtained by calculation. Therefore, the method and the device can solve the technical problem that channel multiplexing in the existing channel-based data synchronization technology easily causes delay inconsistency of the receiving and sending channels, so that current differential protection is subjected to misoperation.
Drawings
Fig. 1 is a schematic flowchart of a current differential protection data synchronization method for an ac line according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a current differential protection data synchronization apparatus for an ac line according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of a current differential protection data synchronization system of an ac line according to an embodiment of the present application;
FIG. 4 is a schematic diagram of a time window of voltage data provided by an embodiment of the present application;
the reference numbers are as follows:
a sending end equivalent power supply 1; a first bus bar 2; a second bus bar 3; a receiving end equivalent power source 4; an A AC line 5; a B AC line 6; a C-phase AC line 7; a transmission-side relay protection device 8; and a receiving end relay protection device 9.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
For easy understanding, referring to fig. 1, a first embodiment of a method for synchronizing current differential protection data of an ac line provided by the present application includes:
and step 101, when the AC line has a fault, respectively calculating the difference of the effective values of the measured voltages of the three-phase line before and after the starting of the starting element, and selecting the maximum phase corresponding to the maximum value of the difference of the effective values of the measured voltages.
It should be noted that, the difference between the effective values of the measured voltages is calculated to determine a fault phase in the three-phase ac line, and the phase with the largest difference between the effective values of the measured voltages is the fault phase, i.e. the maximum phase, and after the fault phase is determined, data acquisition and calculation and analysis operations can be performed specifically.
Further, step 101 is preceded by: when the AC line has a fault, transmitting the transmitting end measurement voltage and the transmitting end current instantaneous value to a receiving end protection device; correspondingly, when the alternating current line has a fault, the instantaneous values of the receiving-end measured voltage and the receiving-end current are sent to the sending-end protection device.
When the AC line has a fault, after the starting elements on the two sides are started, the protection devices on the two sides of the line transmit the measured voltage and current instantaneous values of the respective sides to the relay protection device on the opposite side of the line; that is, the transmitting terminal measurement voltage and the transmitting terminal current instantaneous value are transmitted to the receiving terminal protection device, and the receiving terminal measurement voltage and the receiving terminal current instantaneous value are transmitted to the transmitting terminal protection device.
Further, when the ac line is failed, the difference between the effective values of the measured voltages of the three-phase line in the half cycle before the start of the starting device and in the half cycle after the start of the starting device may be calculated, and the failed phase corresponding to the maximum value of the difference between the effective values of the measured voltages may be selected. The specific calculation formula is as follows:
wherein, Delta UiRepresenting the difference between the effective values of the measured voltages of the i-th phase line, i being three phases a, b and c, tsTo start the component start-up time, uMi(t) represents the measured voltage of the i-th phase line.
And 102, calculating the calculated voltage of the preset time period before and after the starting of the element at the protected installation position of the receiving end corresponding to the maximum according to the line parameters, the measured voltage of the sending end and the measured current of the sending end, wherein the calculated voltage comprises the calculation starting time and the calculation ending time.
It should be noted that the activation times of the protection devices on both sides are the same, that is, the activation time of the receiving end activation element is tsThe voltage change condition of the receiving end can be calculated or estimated according to the related parameters of the transmitting end by using tjqDenotes the calculation start time, tjzIndicating the calculation termination time, and the preset time period is tjq～tjzThe data length of the calculated voltage may be represented as L ═ tjz-tjq. According to the actual situation, t also needs to be satisfiedjq≤ts≤tjz. The calculation method for calculating the voltage is as follows:
where x denotes the faulted phase, y, z the other two phases, uMNx(t) represents the calculated voltage of the receiving end corresponding to the fault phase line, i.e. the calculated voltage of the preset time period, uMx(t)、iMx(t) represents the measured voltage at the transmitting end and the measured current at the transmitting end corresponding to the faulty phase line, iMy(t)、iMz(t) measuring currents, r, for the other two phases at the sending end, respectivelys、lsAre respectively the self-resistance, self-inductance, r of the fault phase linemxy、rmxz、lmxyAnd lmxzRespectively of faulty phase line and other two-phase lineMutual resistance and mutual inductance, and λ represents the total length of the line.
And 103, selecting a matching time period according to the starting time of the receiving end starting element, wherein the matching time period comprises a matching starting time and a matching ending time.
It should be noted that, the specific selection method is as follows: selecting a preset time before the starting time of the receiving end starting element as a matching starting time; and selecting a preset time after the starting time of the receiving end starting element as the matching termination time. Matching the starting time tqCan be expressed as: t is tq＝ts-t1Matching the end time tzCan be expressed as: t is tz＝ts+t2Wherein t is1And t2A preset fixed duration. There are some constraints on the matching period, i.e. the matching start time tqShould be less than the calculation start time tjqMatching the end time tzShould be greater than the calculation termination time tjzAnd match the starting time tqTo the starting time tsShould be less than the length L-t of the preset time periodjz-tjqPlease refer to fig. 4 for a detailed description. Can be described by the inequality:
tq＜tjq,tz＞tjz,ts-tq＜tjz-tjq＝L。
and step 104, taking the matched starting time as the measurement starting time of the receiving end measurement voltage, and selecting a target measurement voltage of a preset time period from the receiving end measurement voltage, wherein the target measurement voltage comprises the measurement starting time and the measurement ending time.
Note that the measurement start time is tcqThe measurement termination time is tczThe length of the data of the voltage is obtained and calculated, i.e. the preset time period L ═ tjz-tjqThe consistent target measurement voltage is for the convenience of waveform matching, and according to the description, the relationship between the measurement time and other times can be expressed as:
tcq＝tq,tcz-tcq＝tjz-tjq＝L；
obtained is tcq～tczThe target of (1) measures a voltage.
And 105, calculating the waveform similarity between the target measurement voltage and the calculated voltage.
It should be noted that the formula for calculating the waveform similarity between the target measurement voltage and the calculation voltage is expressed as:
wherein, p (u)MNx,uNx) Calculating voltage u representing receiving end corresponding to fault phase lineMNxWith a target measurement voltage uNxWaveform similarity of (1), tMNx、tNxCalculating the voltage u for the receiving terminals respectivelyMNx(tMNx) And a target measurement voltage uNx(tNx) The time of sampling of the (c) clock,
is uMNx(tMNx) In the time interval tjq,tjz]The average value of the values of (a) to (b),
is uNx(tNx) In the time interval tcq,tcz]Average value of (d).
And step 106, if the measurement starting moment is less than the starting moment and the measurement ending moment is less than the matching ending moment, moving the matching starting moment backwards by a preset sampling interval, returning to the step of taking the matching starting moment as the measurement starting moment of the voltage measured by the receiving end, otherwise, judging whether the maximum waveform similarity is less than a similarity threshold value, if so, obtaining a null value result, and if not, subtracting the measurement starting moment corresponding to the maximum waveform similarity from the calculation starting moment to obtain a moment error between the alternating current line of the sending end and the alternating current line of the receiving end.
It should be noted that, referring to fig. 4, if the starting time t is measuredcqLess than starting time tsAnd at the termination of the measurementMoment tczLess than the matching termination time tzThe matching start time is shifted backward by a preset sampling interval delta T to obtain an updated matching start time T'q＝tqAnd + delta T, then, the matched initial time is used as the measurement initial time of the measured voltage of the receiving end again, namely, the measurement initial time is synchronously updated, the target measured voltage is selected again, and then the waveform similarity is calculated. Under the condition that the condition is met, the operation steps can be repeated all the time to obtain a plurality of waveform similarity values, and if the condition is not met, the maximum waveform similarity p (u) is found from the obtained waveform similaritiesMNx,uNx)maxAt this time, the measurement start time of the corresponding target measurement voltage data is tcqmaxWith a similarity threshold of psetIf it is p (u)MNx,uNx)max＜psetThen a null result is obtained, if p (u)MNx,uNx)max≥psetThe time error deltat can be calculatede：
Δte＝tcqmax-tjq。
And step 107, carrying out synchronous adjustment on the current differential protection data according to the time error.
In the current differential protection data synchronization method for the alternating-current line provided by this embodiment, firstly, the fault phase of the three-phase line is determined according to the starting condition of the starting element; then, calculating the voltage change condition of the receiving end by using the voltage measured by the transmitting end of the fault phase and related line parameters, namely calculating the voltage; and finally, waveform matching can be carried out between the target measurement voltage before and after the starting of the receiving-end starting element and the calculated voltage, and the sampling time error between the alternating-current lines on the two sides, namely the time error, can be obtained according to the maximum value of the waveform similarity obtained by calculation. Therefore, the embodiment can solve the technical problem that channel multiplexing in the existing channel-based data synchronization technology easily causes delay inconsistency of the receiving and sending channels, so that current differential protection is subjected to misoperation.
For easy understanding, referring to fig. 2, the present application further provides an embodiment of a current differential protection data synchronization apparatus for an ac line, including:
the first calculating module 201 is configured to, when the ac line fails, respectively calculate a difference between effective values of measured voltages of the three-phase line before and after the start of the starting element, and select a maximum phase corresponding to a maximum value of the difference between the effective values of the measured voltages;
the second calculation module 202 is configured to calculate a calculated voltage of a preset time period before and after starting the element at the protected installation location of the receiving terminal corresponding to the maximum voltage according to the line parameter, the measured voltage at the sending terminal, and the measured current at the sending terminal, where the calculated voltage includes a calculation start time and a calculation stop time;
the first selection module 203 is configured to select a matching time period according to the starting time of the receiving-end starting element, where the matching time period includes a matching starting time and a matching ending time;
a second selecting module 204, configured to use the matching start time as a measurement start time of the receiving-end measurement voltage, and select a target measurement voltage of a preset time period from the receiving-end measurement voltage, where the target measurement voltage includes the measurement start time and the measurement termination time;
a third calculation module 205, configured to calculate a waveform similarity between the target measured voltage and the calculated voltage;
a determining module 206, configured to, if the measurement start time is less than the start time and the measurement end time is less than the matching end time, move the matching start time backward by a preset sampling interval to trigger the second selecting module 204, otherwise, determine whether the maximum waveform similarity is less than a similarity threshold, if yes, obtain a null result, and if not, obtain a time error between the transmission-end ac line and the reception-end ac line by subtracting the measurement start time corresponding to the maximum waveform similarity from the calculation start time;
and the synchronization module 207 is configured to perform current differential protection data synchronization adjustment according to the time error.
Further, still include:
the data transmission module transmits the transmitting end measured voltage and the transmitting end current instantaneous value to the receiving end protection device when the alternating current circuit fails;
correspondingly, when the alternating current line has a fault, the instantaneous values of the receiving-end measured voltage and the receiving-end current are sent to the sending-end protection device.
Further, the first selection module is specifically configured to:
selecting a preset time before the starting time of the receiving end starting element as a matching starting time;
and selecting a preset time after the starting time of the receiving end starting element as the matching termination time.
For ease of understanding, referring to fig. 3, the present application further provides an embodiment of a current differential protection data synchronization system for an ac line, comprising: a transmitting end equivalent power supply 1, a receiving end equivalent power supply 4, a first bus 2, a second bus 3, a transmitting end relay protection device 8, a receiving end relay protection device 9 and an ABC three-phase alternating-current circuit;
a first terminal of the ABC three-phase alternating current line is connected with the sending end equivalent power supply through a first bus, and a second terminal of the ABC three-phase alternating current line is connected with the sending end equivalent power supply through a second bus;
the sending end relay protection device is arranged on an ABC three-phase alternating current circuit connected with the first bus;
and the receiving end relay protection device is arranged on an ABC three-phase alternating current circuit connected with the second bus.
Note that, referring to fig. 3, the ABC three-phase ac line includes an a-phase ac line 5, a B-phase ac line 6, and a C-phase ac line 7.
The application also provides a current differential protection data synchronization device of an alternating current line, the device comprising a processor and a memory:
the memory is used for storing the program codes and transmitting the program codes to the processor;
the processor is configured to implement the method for current differential protection data synchronization of ac lines in the foregoing method embodiments according to instructions in the program code.
The present application also provides a computer readable storage medium for storing program code for performing the method for current differential protection data synchronization of an ac line in the aforementioned method embodiments.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for executing all or part of the steps of the method described in the embodiments of the present application through a computer device (which may be a personal computer, a server, or a network device). And the aforementioned storage medium includes: a U disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (10)
1. A method for synchronizing current differential protection data of an AC line, comprising:
when the AC line has a fault, respectively calculating the difference of the effective values of the measured voltages of the three-phase line before and after the starting of the starting element, and selecting the maximum phase corresponding to the maximum value of the difference of the effective values of the measured voltages;
calculating the calculated voltage of a preset time period before and after the starting of the starting element at the maximum corresponding protected installation position of the receiving end according to the line parameters, the measured voltage of the transmitting end and the measured current of the transmitting end, wherein the calculated voltage comprises a calculation starting time and a calculation ending time;
selecting a matching time period according to the starting time of a receiving end starting element, wherein the matching time period comprises a matching starting time and a matching ending time;
taking the matching starting time as the measurement starting time of the receiving end measurement voltage, and selecting the target measurement voltage of the preset time period from the receiving end measurement voltage, wherein the target measurement voltage comprises the measurement starting time and the measurement ending time;
calculating waveform similarity between the target measurement voltage and the calculated voltage;
if the measurement starting time is smaller than the starting time and the measurement ending time is smaller than the matching ending time, moving the matching starting time backwards by a preset sampling interval, returning to the step of taking the matching starting time as the measurement starting time of the voltage measured by the receiving end, otherwise, judging whether the maximum waveform similarity is smaller than a similarity threshold value, if so, obtaining a null value result, and if not, subtracting the measurement starting time corresponding to the maximum waveform similarity from the calculation starting time to obtain a time error between the sending end alternating current line and the receiving end alternating current line;
and carrying out synchronous adjustment on the current differential protection data according to the time error.
2. The method for synchronizing current differential protection data of an ac line according to claim 1, wherein the step of calculating the difference between the effective values of the measured voltages of the three-phase line before and after the start of the startup element when the ac line fails further comprises:
when the AC line has a fault, transmitting the transmitting end measured voltage and the transmitting end current instantaneous value to a receiving end protection device;
correspondingly, when the alternating current line has a fault, the instantaneous values of the receiving-end measured voltage and the receiving-end current are sent to the sending-end protection device.
3. The method for synchronizing current differential protection data of an ac line according to claim 1, wherein the step of calculating a difference between effective values of measured voltages of the three-phase line before and after the start of the startup element and selecting a maximum phase corresponding to a maximum value of the difference between the effective values of the measured voltages, when the ac line fails, comprises:
when the AC line has a fault, the difference between the effective values of the measured voltages of the three-phase line in the half cycle before the start of the starting element and the half cycle after the start of the starting element is calculated respectively, and the maximum phase corresponding to the maximum value of the difference of the effective values of the measured voltages is selected.
4. The ac line current differential protection data synchronization method according to claim 1, wherein the selecting a matching period according to the activation time of the receiving-side activation element, the matching period including a matching start time and a matching end time, comprises:
selecting a preset time before the starting time of the receiving end starting element as a matching starting time;
and selecting a preset time after the starting time of the receiving end starting element as the matching termination time.
5. A current differential protection data synchronization device for an AC line, comprising:
the first calculation module is used for respectively calculating the difference of the effective values of the measured voltages of the three-phase line before and after the starting element is started when the alternating-current line has a fault, and selecting the maximum phase corresponding to the maximum value of the difference of the effective values of the measured voltages;
the second calculation module is used for calculating the calculation voltage of the preset time period before and after the starting of the starting element at the maximum corresponding protected installation position of the receiving end according to the line parameters, the measured voltage of the sending end and the measured current of the sending end, wherein the calculation voltage comprises the calculation starting time and the calculation stopping time;
the device comprises a first selection module, a second selection module and a third selection module, wherein the first selection module is used for selecting a matching time period according to the starting time of a receiving end starting element, and the matching time period comprises a matching starting time and a matching ending time;
a second selection module, configured to use the matching start time as a measurement start time of a receiving-end measurement voltage, and select a target measurement voltage of the preset time period from the receiving-end measurement voltage, where the target measurement voltage includes the measurement start time and a measurement termination time;
the third calculation module is used for calculating the waveform similarity between the target measurement voltage and the calculated voltage;
a judging module, configured to move the matching start time backward by a preset sampling interval if the measurement start time is less than the start time and the measurement end time is less than the matching end time, and trigger the second selecting module, otherwise, judge whether a maximum waveform similarity is less than a similarity threshold, if yes, obtain a null result, and if not, difference the measurement start time corresponding to the maximum waveform similarity with the calculation start time, and obtain a time error between the sending-end ac line and the receiving-end ac line;
and the synchronization module is used for carrying out current differential protection data synchronization adjustment according to the time error.
6. The ac line current differential protection data synchronization device according to claim 5, further comprising:
the data transmission module is used for transmitting the transmitting end measured voltage and the transmitting end current instantaneous value to the receiving end protection device when the alternating current circuit fails;
correspondingly, when the alternating current line has a fault, the instantaneous values of the receiving-end measured voltage and the receiving-end current are sent to the sending-end protection device.
7. The ac line current differential protection data synchronization device according to claim 5, wherein the first selection module is specifically configured to:
selecting a preset time before the starting time of the receiving end starting element as a matching starting time;
and selecting a preset time after the starting time of the receiving end starting element as the matching termination time.
8. An ac line current differential protection data synchronization system for performing the method of claims 1-4, comprising: the system comprises a transmitting end equivalent power supply, a receiving end equivalent power supply, a first bus, a second bus, a transmitting end relay protection device, a receiving end relay protection device and an ABC three-phase alternating-current line;
a first terminal of the ABC three-phase alternating-current line is connected with the sending-end equivalent power supply through the first bus, and a second terminal of the ABC three-phase alternating-current line is connected with the receiving-end equivalent power supply through the second bus;
the sending end relay protection device is arranged on the ABC three-phase alternating-current circuit connected with the first bus;
and the receiving end relay protection device is arranged on the ABC three-phase alternating-current circuit connected with the second bus.
9. An ac line current differential protection data synchronization apparatus, comprising a processor and a memory:
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is configured to execute the method of current differential protection data synchronization of an ac line according to any of claims 1-4 in accordance with instructions in the program code.
10. A computer readable storage medium for storing program code for performing the method of current differential protection data synchronization of an ac line according to any one of claims 1 to 4.
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