CN108666990B - Power grid differential protection method and system - Google Patents
Power grid differential protection method and system Download PDFInfo
- Publication number
- CN108666990B CN108666990B CN201810581368.XA CN201810581368A CN108666990B CN 108666990 B CN108666990 B CN 108666990B CN 201810581368 A CN201810581368 A CN 201810581368A CN 108666990 B CN108666990 B CN 108666990B
- Authority
- CN
- China
- Prior art keywords
- differential protection
- protection device
- current
- sampling
- head end
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
- H02H7/263—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 measured values
Landscapes
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention discloses a power grid differential protection method and system. The method comprises the following steps: synchronizing sampling moments of a head end differential protection device and a tail end differential protection device; the method comprises the steps that a head end differential protection device and a tail end differential protection device respectively collect the current amplitude and the power direction of a line of a jurisdiction section at an installation position at a first set time interval from a sampling moment; and transmitting the collected current amplitude and power direction to the other side; and the head end differential protection device and the tail end differential protection device respectively determine whether the line in the jurisdiction area has a fault according to the current amplitude and the power direction acquired by the head end differential protection device and the tail end differential protection device and the current amplitude and the power direction sent by the opposite end. The power grid differential protection method and the power grid differential protection system have the characteristics of simple implementation mode and high fault judgment accuracy.
Description
Technical Field
The invention relates to the field of power grid protection, in particular to a power grid differential protection method and system.
Background
Along with the continuous development of national distribution networks and the continuous improvement of the automation degree of the distribution networks, the requirement on the reliability of power supply is higher and higher. The reliability of power supply is an important index for measuring the quality of power supply and distribution, and is generally expressed by the percentage of the annual average power supply time to the annual time, for example, the annual time is 8760 hours, the annual average power failure time of a user is 87.6 hours, namely, the power failure time is 1% of the annual time, and the power supply reliability is 99%.
Various intelligent measurement and control and protection devices for distribution network automation are important guarantees for improving power supply reliability, particularly fault isolation and power supply self-recovery functions in a power distribution network, and an optical fiber differential protection technology and the device thereof have incomparable advantages for rapidly isolating faults of the power distribution network in a 10KV medium-voltage system distribution network of a power system, and initially have implementation conditions in China, and are planned and implemented in partial areas of the power network in the south at present.
The implementation mode of the optical fiber differential protection: the line differential protection generally refers to the pilot protection of a transmission line, that is, the protection devices at two ends of the transmission line are longitudinally connected by using an optical fiber communication channel, the electrical quantities (current, power direction, etc.) at each end are transmitted to the opposite end, and the electrical quantities at the two ends are compared to judge whether a fault is in the range of the line or out of the range of the line, so as to determine whether to cut off the protected line. However, in the prior art, the differential protection of the power transmission line is complex in implementation mechanism, and has high requirement on the reliability of network transmission equipment. In addition, synchronous sampling of data needs to eliminate communication delay of network communication, which affects accuracy of fault judgment.
Disclosure of Invention
The invention aims to provide a power grid differential protection method and a power grid differential protection system, which have the characteristics of simple implementation mode and high fault judgment accuracy.
In order to achieve the purpose, the invention provides the following scheme:
a method of grid differential protection, the method comprising:
synchronizing sampling moments of a head end differential protection device and a tail end differential protection device, wherein the head end differential protection device and the tail end differential protection device are respectively installed at two ends of a line of a jurisdiction section;
the head end differential protection device collects the current of the line of the domination section at the installation position of the head end differential protection device at a first set time interval from the sampling moment, and records the current as head end sampling current, wherein the head end sampling current comprises the amplitude and the power direction of the current;
the head end differential protection device sends the head end sampling current to the tail end differential protection device;
the tail end differential protection device collects the current of the line of the jurisdiction section where the tail end differential protection device is installed at the first set time interval from the sampling moment, and records the current as tail end sampling current, wherein the tail end sampling current comprises the amplitude and the power direction of the current;
the tail end differential protection device sends the tail end sampling current to the head end differential protection device;
the head end differential protection device determines whether the line of the jurisdiction section has a fault according to the head end sampling current and the tail end sampling current;
and the tail end differential protection device determines whether the line of the jurisdiction section has a fault according to the head end sampling current and the tail end sampling current.
Optionally, the method further includes:
and synchronizing the sampling time of the head end differential protection device and the tail end differential protection device at intervals of a second set time interval.
Optionally, the sampling time of the synchronous head end differential protection device and the sampling time of the tail end differential protection device specifically include:
the head end differential protection device sends a synchronous instruction to the tail end differential protection device;
after the tail end differential protection device receives the synchronous instruction, opening PCA interruption;
and the head end differential protection device sends the synchronous pulse to a PCA interrupt pin of the tail end differential protection device to generate interrupt, and the sampling time is synchronized.
Optionally, before the head end differential protection device sends the head end sampled current to the tail end differential protection device, the method further includes:
calculating the real part and the imaginary part of the head end sampling current by adopting a window recursive Fourier algorithm, and numbering sampling points;
before the tail end differential protection device sends the tail end sampled current to the head end differential protection device, the method further comprises the following steps:
and calculating the real part and the imaginary part of the tail end sampling current by adopting a window recursive Fourier algorithm, and numbering the sampling points.
Optionally, determining whether the line in the jurisdiction section has a fault according to the head end sampling current and the tail end sampling current specifically includes:
calculating a difference current between the head end sampling current and the tail end sampling current at the same moment;
judging whether the difference current exceeds a set value or not;
if so, the jurisdiction line fails.
The invention also provides a power grid differential protection system, which comprises:
the synchronous unit is used for synchronizing sampling moments of a head end differential protection device and a tail end differential protection device, and the head end differential protection device and the tail end differential protection device are respectively installed at two ends of a line of a jurisdiction section;
the head end sampling unit is used for acquiring the current of the line of the domination section at the installation position of the head end differential protection device at a first set time interval from the sampling moment by the head end differential protection device, and recording the current as a head end sampling current, wherein the head end sampling current comprises the amplitude value and the power direction of the current;
the head end sending unit is used for sending the head end sampling current to the tail end differential protection device by the head end differential protection device;
the tail end sampling unit is used for collecting the current of the line of the jurisdiction section at the installation position of the tail end differential protection device at the first set time interval from the sampling moment by the tail end differential protection device, and recording the current as tail end sampling current, wherein the tail end sampling current comprises the amplitude and the power direction of the current;
the tail end transmitting unit is used for transmitting the tail end sampling current to the head end differential protection device by the tail end differential protection device;
the head end fault determining unit is used for judging whether the line of the jurisdiction section has a fault or not by the head end differential protection device according to the head end sampling current and the tail end sampling current;
and the tail end fault determining unit is used for judging whether the line of the jurisdiction area has a fault or not by the tail end differential protection device according to the head end sampling current and the tail end sampling current.
Optionally, the system further includes:
and the sampling time correction unit is used for synchronizing the sampling time of the head end differential protection device and the tail end differential protection device once every second set time interval.
Optionally, the synchronization unit specifically includes:
the command sending subunit is used for sending a synchronous command to the tail end differential protection device by the head end differential protection device;
the interruption opening subunit is used for opening the PCA interruption after the terminal differential protection device receives the synchronous instruction;
and the sampling time synchronization subunit is used for sending the synchronization pulse to a PCA (principal component analysis) interrupt pin of the tail end differential protection device by the head end differential protection device to generate interrupt, and synchronizing the sampling time.
Optionally, the system further includes:
the head end sampling current processing unit is used for calculating a real part and an imaginary part of the head end sampling current by adopting a window recursive Fourier algorithm and marking sampling point numbers;
and the tail end sampling current processing unit is used for calculating a real part and an imaginary part of the tail end sampling current by adopting a window recursive Fourier algorithm and marking the number of an upper sampling point.
Optionally, the head-end fault determining unit specifically includes:
the head end differential current calculating subunit is used for calculating the differential current between the head end sampling current and the tail end sampling current at the same moment;
the head end differential current judging subunit is used for judging whether the differential current exceeds a set value;
the head end fault determining subunit is used for determining that the line of the jurisdiction section has a fault when the differential current exceeds a set value;
the terminal fault determination unit specifically includes:
the tail end differential current calculating subunit is used for calculating the differential current between the head end sampling current and the tail end sampling current at the same moment;
a terminal difference current judgment subunit for judging whether the difference current exceeds a set value;
and the tail end fault determining subunit is used for determining that the line of the jurisdiction section has a fault when the difference current exceeds a set value.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects: the power grid differential protection method and the power grid differential protection system provided by the invention synchronize the data sampling of the differential protection devices at two ends of the line of the jurisdiction section, and correct the synchronization of the sampling moments of the differential protection devices at two ends of the line of the jurisdiction section at intervals of set time, so that the realization mechanism is simple. The data sampling synchronization adopts a mode of synchronous instruction and synchronous pulse, so that the synchronous starting sampling of the equipment at two ends can be effectively ensured, and a data synchronization mechanism is greatly optimized. The data sampling is corrected by adopting a mode of correcting instructions and correcting pulses, so that the synchronism of data sampling of the equipment at two ends in the long-time running process can be effectively ensured. In addition, the calculation of the sampled data adopts a window recursive Fourier algorithm, the amplitude value and the power direction of the current at two ends at the same time are reflected, and the data transmission mode adopts a real part mode and an imaginary part mode of a transmission current value, so that the transmission capacity of the data at two ends is greatly reduced, the error probability of data transmission is reduced, the stability and the reliability of data communication are improved, and further, the accuracy of fault judgment is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a differential protection method for a power grid according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of information transmission between a head-end differential protection device and a tail-end differential protection device according to an embodiment of the present invention;
FIG. 3 is a timing interrupt sampling diagram according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating sample time drift according to an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating sample time correction according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a power grid differential protection system according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, 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 invention.
The invention aims to provide a power grid differential protection method and a power grid differential protection system, which have the characteristics of simple implementation mode and high fault judgment accuracy.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a flowchart of a differential protection method for a power grid according to an embodiment of the present invention, and as shown in fig. 1, the differential protection method for a power grid provided by the present invention specifically includes the following steps:
step 101: synchronizing sampling moments of a head end differential protection device and a tail end differential protection device, wherein the head end differential protection device and the tail end differential protection device are respectively installed at two ends of a domination section line, the domination section line is a section of line in a power transmission line, and the differential protection devices are installed in power distribution rooms at two ends of the section of line;
step 102: the head end differential protection device collects the current of the line of the domination section at the installation position of the head end differential protection device at a first set time interval from the sampling moment, and records the current as head end sampling current, wherein the head end sampling current comprises the amplitude and the power direction of the current;
step 103: the head end differential protection device sends the head end sampling current to the tail end differential protection device;
step 104: the tail end differential protection device collects the current of the line of the jurisdiction section where the tail end differential protection device is installed at the first set time interval from the sampling moment, and records the current as tail end sampling current, wherein the tail end sampling current comprises the amplitude and the power direction of the current;
step 105: the tail end differential protection device sends the tail end sampling current to the head end differential protection device;
step 106: the head end differential protection device determines whether the line of the jurisdiction section has a fault according to the head end sampling current and the tail end sampling current;
step 107: and the tail end differential protection device determines whether the line of the jurisdiction section has a fault according to the head end sampling current and the tail end sampling current.
The method further comprises the following steps:
and synchronizing the sampling time of the head end differential protection device and the tail end differential protection device at intervals of a second set time interval.
Before the head end differential protection device sends the head end sampled current to the tail end differential protection device, the method further includes:
calculating the real part and the imaginary part of the head end sampling current by adopting a window recursive Fourier algorithm, and numbering sampling points;
before the tail end differential protection device sends the tail end sampled current to the head end differential protection device, the method further comprises the following steps:
and calculating the real part and the imaginary part of the tail end sampling current by adopting a window recursive Fourier algorithm, and numbering the sampling points.
Wherein, step 101 specifically includes:
the head end differential protection device sends a synchronous instruction to the tail end differential protection device;
after the tail end differential protection device receives the synchronous instruction, opening PCA interruption;
and the head end differential protection device sends the synchronous pulse to a PCA interrupt pin of the tail end differential protection device to generate interrupt, and the sampling time is synchronized.
The determining whether the line of the jurisdiction section has a fault according to the head end sampling current and the tail end sampling current specifically includes:
calculating a difference current between the head end sampling current and the tail end sampling current at the same moment;
judging whether the difference current exceeds a set value or not;
if so, the jurisdiction line fails.
Three-phase current analog signal (I) with fundamental wave frequency of 50 Hza/Ib/Ic) Analog-to-digital conversion is carried out through a multi-channel analog-to-digital converter, a main controller of a head-end differential protection device (a tail-end differential protection device) obtains analog-to-digital conversion data through an SPI (serial peripheral interface) bus for calculation, meanwhile, the main controller receives three-phase current data from an opposite end through a 1X9 optical transceiver, and the three-phase current data obtained by local sampling and the three-phase current data from the opposite end form split-phase differential protection. The master controller obtains a real-time clock through a high-precision temperature compensation type clock chip and stores the generated SOE event into a ferroelectric memory of the SPI. The main controller transmits the three-phase current data of the local machine to the opposite end through the 1X9 optical transceiver. The pulse sending port and the transmitting port phase of the main controller are connected with the transmitting end of the 1X9 optical transceiver, and the receiving end of the main controller is connected with the interrupt port pin and then connected with the receiving end of the 1X9 optical transceiver.
The head end differential protection device is an initiator of data sampling synchronization; the end differential protection device data samples are synchronized. Full duplex communication, the information transmission direction is as shown in fig. 2.
The transmitting end and the receiving end of the 1X9 optical transceiver are TTL level and can be directly connected with the asynchronous transceiver of the main controller.
The head end differential protection device comprises a head end differential protection device, a pulse transmission port, a data transmission interface and a data transmission interface, wherein the head end differential protection device is used for transmitting data; the pulse transmission port of the master controller transmits pulses for synchronization of data sampling and data sampling correction, hereinafter referred to as synchronization pulses or correction pulses. When the synchronous pulse or the correction pulse is sent, the information transmitting port is in a high level state. The transmission of the pulse belongs to the authority of the head end differential protection device.
The PCA interrupt belongs to the authority of the terminal differential protection device, and the triggering mode of the PCA interrupt is set to be edge triggering. The PCA interruption is shielded when the receiving end of the terminal differential protection device normally receives data; the PCA interrupt is opened at the time of receiving the synchronization pulse. The PCA interruption of the head end differential protection device is always in a masked state.
The data sampling synchronization process is divided into the following parts:
data sampling synchronization: the data sampling synchronization is mainly to synchronize the starting time of data sampling, and is initiated by the head end differential protection device, so that the head end differential protection device and the tail end differential protection device start sampling at the same time. The head end differential protection device firstly sends a synchronization instruction through an information transmitting port to inform the tail end differential protection device of preparing a synchronous sampling moment; and after receiving the synchronization command, the tail end differential protection device opens the PCA interrupt to prepare for receiving the synchronization pulse. Then the head end differential protection device sends synchronous pulse through a pulse sending port, the synchronous pulse is transmitted to a PCA pin of the tail end differential protection device through an optical fiber to generate interruption, and the tail end differential protection device immediately starts sampling of analog quantity.
And (3) data sampling correction: the data sampling correction is to alternately execute the operation in the next long-time sampling process after the data synchronization is finished. The purpose is as follows: although the oscillation frequencies of the main controller crystal oscillators of the head end differential protection device and the tail end differential protection device are theoretically consistent, time accumulation errors can exist in the long-time operation process due to device differences, and data sampling correction is designed for eliminating the errors. The head end differential protection device firstly sends a correction instruction through the information transmitting port to inform the tail end differential protection device to prepare for correcting the sampling time; and after receiving the correction command, the terminal differential protection device opens the PCA interrupt to prepare for receiving the correction pulse. And then the head end differential protection device sends a correction pulse through a pulse sending port, the correction pulse is transmitted to a PCA pin of the tail end differential protection device through an optical fiber to generate interruption, and the tail end differential protection device corrects the sampling time of the analog quantity in real time.
And (3) data calculation: the data calculation of the scheme of the invention adopts a window recursive Fourier algorithm to calculate the real part and the imaginary part of the analog quantity. The head end differential protection device and the tail end differential protection device adopt a sampling point of a whole cycle before the moment to carry out Fourier calculation at the same moment.
Data transmission: the transmission amount of data is three analog quantities (I)a/Ib/Ic) The real part and the imaginary part are simultaneously numbered with sampling points, so that the same data can be checked by the opposite terminal convenientlyAnd the data can be effectively prevented from being transmitted in a staggered way.
Out-of-sync resynchronization of data samples: the out-of-step resynchronization of data sampling is designed in consideration of the out-of-step of data sampling caused by some factors (such as strong electromagnetic interference and the like) in the operation process of the device. The synchronization process is as described above.
The correction mode and process of data sampling: the data sampling adopts equal time interval to start A/D conversion, and the analog quantity is dispersed. The explanation is given by taking 24-point cycle sampling as an example:
sampling by adopting a timed interruption mode: the timing time of one cycle 24 point is 20ms/24 ═ 833.33us, that is, 1 a/D conversion is started after the interruption is timed every 833.33us, and a square wave diagram of sampling time on the time axis is shown in fig. 3, where t in fig. 3 is a square wave diagram1＝t2＝…t24833.33 us. Assuming that the main controllers of the head end differential protection device and the tail end differential protection device are completely consistent with the crystal oscillator performance parameters, the sampling at the two ends passes through the synchronous sampling starting time, so that the sampling time diagrams at the two ends are completely consistent on a time axis, but the main controllers of the head end differential protection device and the tail end differential protection device are not capable of being completely consistent with the crystal oscillator performance parameters, and the sampling time drifts in the actual operation process, as shown in fig. 4, if the drifts are not corrected, the square waves of the square wave diagrams at the sampling time of the head end differential protection device and the tail end differential protection device are firstly gradually dislocated, then are coincided, are cyclically reciprocated, and the sampling data at the two ends are out of synchronization.
The data sampling correction method of the invention comprises the following steps: the data sampling timing of the tail end differential protection device is corrected based on the data sampling timing of the head end differential protection device, as shown in fig. 5. The correction process is as follows: after the tail end differential protection device receives the sampling correction command, opening PCA interruption; the end differential protection device receives the sampling correction pulse to generate a PCA interrupt, and modifies the time of generating the sampling interrupt of the next point in the interrupt service program. And the 1 cycle is corrected twice, so that the data synchronization can be effectively ensured.
The power grid differential protection method provided by the invention synchronizes the data sampling of the differential protection devices at two ends of the line of the jurisdiction section, and corrects the synchronism of the sampling moments of the differential protection devices at two ends of the line of the jurisdiction section at set time intervals, so that the realization mechanism is simple. The data sampling synchronization adopts a mode of synchronous instruction and synchronous pulse, so that the synchronous starting sampling of the equipment at two ends can be effectively ensured, and a data synchronization mechanism is greatly optimized. The data sampling is corrected by adopting a mode of correcting instructions and correcting pulses, so that the synchronism of data sampling of the equipment at two ends in the long-time running process can be effectively ensured. In addition, the calculation of the sampled data adopts a window recursive Fourier algorithm, the amplitude value and the power direction of the current at two ends at the same time are reflected, and the data transmission mode adopts a real part mode and an imaginary part mode of a transmission current value, so that the transmission capacity of the data at two ends is greatly reduced, the error probability of data transmission is reduced, the stability and the reliability of data communication are improved, and further, the accuracy of fault judgment is improved.
The present invention further provides a power grid differential protection system, fig. 6 is a schematic structural diagram of the power grid differential protection system according to the embodiment of the present invention, and as shown in fig. 6, the system includes:
the synchronization unit 601 is configured to synchronize sampling moments of a head end differential protection device and a tail end differential protection device, where the head end differential protection device and the tail end differential protection device are respectively installed at two ends of a jurisdiction circuit, the jurisdiction circuit refers to a section of circuit in a power transmission line, and the differential protection devices are installed in power distribution rooms at two ends of the section of circuit;
a head end sampling unit 602, configured to collect, at a first set time interval from the sampling time, current of a line in the jurisdiction area at which the head end differential protection device is installed, and record the current as a head end sampling current, where the head end sampling current includes an amplitude of the current and a power direction;
a head end sending unit 603, configured to send the head end sampling current to the tail end differential protection device by the head end differential protection device;
a terminal sampling unit 604, configured to collect, by the terminal differential protection device, current of a line in the jurisdiction area at which the terminal differential protection device is installed at the first set time interval from the sampling time, and record the current as a terminal sampling current, where the terminal sampling current includes an amplitude of the current and a power direction;
a tail end sending unit 605, configured to send the tail end sampling current to the head end differential protection device by the tail end differential protection device;
a head end fault determining unit 606, configured to determine, by the head end differential protection device, whether the line in the jurisdiction section has a fault according to the head end sampling current and the tail end sampling current;
and a tail end fault determination unit 607, configured to determine, by the tail end differential protection device, whether the line in the jurisdiction area has a fault according to the head end sampling current and the tail end sampling current.
The system further comprises:
and the sampling time correction unit is used for synchronizing the sampling time of the head end differential protection device and the tail end differential protection device once every second set time interval.
The head end sampling current processing unit is used for calculating a real part and an imaginary part of the head end sampling current by adopting a window recursive Fourier algorithm and marking sampling point numbers;
and the tail end sampling current processing unit is used for calculating a real part and an imaginary part of the tail end sampling current by adopting a window recursive Fourier algorithm and marking the number of an upper sampling point.
Wherein, synchronization unit specifically includes:
the command sending subunit is used for sending a synchronous command to the tail end differential protection device by the head end differential protection device;
the interruption opening subunit is used for opening the PCA interruption after the terminal differential protection device receives the synchronous instruction;
and the sampling time synchronization subunit is used for sending the synchronization pulse to a PCA (principal component analysis) interrupt pin of the tail end differential protection device by the head end differential protection device to generate interrupt, and synchronizing the sampling time.
The head end fault determination unit specifically includes:
the head end differential current calculating subunit is used for calculating the differential current between the head end sampling current and the tail end sampling current at the same moment;
the head end differential current judging subunit is used for judging whether the differential current exceeds a set value;
the head end fault determining subunit is used for determining that the line of the jurisdiction section has a fault when the differential current exceeds a set value;
the terminal fault determination unit specifically includes:
the tail end differential current calculating subunit is used for calculating the differential current between the head end sampling current and the tail end sampling current at the same moment;
a terminal difference current judgment subunit for judging whether the difference current exceeds a set value;
and the tail end fault determining subunit is used for determining that the line of the jurisdiction section has a fault when the difference current exceeds a set value.
The power grid differential protection system provided by the invention synchronizes the data sampling of the differential protection devices at two ends of the line of the jurisdiction section, and corrects the synchronism of the sampling moments of the differential protection devices at two ends of the line of the jurisdiction section at set time intervals, so that the realization mechanism is simple. The data sampling synchronization adopts a mode of synchronous instruction and synchronous pulse, so that the synchronous starting sampling of the equipment at two ends can be effectively ensured, and a data synchronization mechanism is greatly optimized. The data sampling is corrected by adopting a mode of correcting instructions and correcting pulses, so that the synchronism of data sampling of the equipment at two ends in the long-time running process can be effectively ensured. In addition, the calculation of the sampled data adopts a window recursive Fourier algorithm, the amplitude value and the power direction of the current at two ends at the same time are reflected, and the data transmission mode adopts a real part mode and an imaginary part mode of a transmission current value, so that the transmission capacity of the data at two ends is greatly reduced, the error probability of data transmission is reduced, the stability and the reliability of data communication are improved, and further, the accuracy of fault judgment is improved.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (6)
1. A method of grid differential protection, the method comprising:
synchronizing sampling moments of a head end differential protection device and a tail end differential protection device, wherein the head end differential protection device and the tail end differential protection device are respectively installed at two ends of a line of a jurisdiction section;
the head end differential protection device collects the current of the line of the domination section at the installation position of the head end differential protection device at a first set time interval from the sampling moment, and records the current as head end sampling current, wherein the head end sampling current comprises the amplitude and the power direction of the current;
the head end differential protection device sends the head end sampling current to the tail end differential protection device;
the tail end differential protection device collects the current of the line of the jurisdiction section where the tail end differential protection device is installed at the first set time interval from the sampling moment, and records the current as tail end sampling current, wherein the tail end sampling current comprises the amplitude and the power direction of the current;
the tail end differential protection device sends the tail end sampling current to the head end differential protection device;
the head end differential protection device determines whether the line of the jurisdiction section has a fault according to the head end sampling current and the tail end sampling current;
the tail end differential protection device determines whether the line of the jurisdiction section has a fault according to the head end sampling current and the tail end sampling current;
the method further comprises the following steps:
synchronizing the sampling time of the head end differential protection device and the tail end differential protection device every a second set time interval;
wherein, the sampling moment of synchronous head end differential protection device and end differential protection device specifically includes:
the head end differential protection device sends a synchronous instruction to the tail end differential protection device;
after the tail end differential protection device receives the synchronous instruction, opening PCA interruption;
and the head end differential protection device sends the synchronous pulse to a PCA interrupt pin of the tail end differential protection device to generate interrupt, and the sampling time is synchronized.
2. The method of claim 1, wherein before the head end differential protection device sends the head end sampled current to the tail end differential protection device, further comprising:
calculating the real part and the imaginary part of the head end sampling current by adopting a window recursive Fourier algorithm, and numbering sampling points;
before the tail end differential protection device sends the tail end sampled current to the head end differential protection device, the method further comprises the following steps:
and calculating the real part and the imaginary part of the tail end sampling current by adopting a window recursive Fourier algorithm, and numbering the sampling points.
3. The method according to claim 1, wherein the determining whether the jurisdiction line has a fault according to the head-end sampled current and the tail-end sampled current specifically comprises:
calculating a difference current between the head end sampling current and the tail end sampling current at the same moment;
judging whether the difference current exceeds a set value or not;
if so, the jurisdiction line fails.
4. A grid differential protection system, characterized in that the system comprises:
the synchronous unit is used for synchronizing sampling moments of a head end differential protection device and a tail end differential protection device, and the head end differential protection device and the tail end differential protection device are respectively installed at two ends of a line of a jurisdiction section;
the head end sampling unit is used for acquiring the current of the line of the domination section at the installation position of the head end differential protection device at a first set time interval from the sampling moment by the head end differential protection device, and recording the current as a head end sampling current, wherein the head end sampling current comprises the amplitude value and the power direction of the current;
the head end sending unit is used for sending the head end sampling current to the tail end differential protection device by the head end differential protection device;
the tail end sampling unit is used for collecting the current of the line of the jurisdiction section at the installation position of the tail end differential protection device at the first set time interval from the sampling moment by the tail end differential protection device, and recording the current as tail end sampling current, wherein the tail end sampling current comprises the amplitude and the power direction of the current;
the tail end transmitting unit is used for transmitting the tail end sampling current to the head end differential protection device by the tail end differential protection device;
the head end fault determining unit is used for judging whether the line of the jurisdiction section has a fault or not by the head end differential protection device according to the head end sampling current and the tail end sampling current;
the tail end fault determining unit is used for judging whether the line of the jurisdiction section has a fault or not by the tail end differential protection device according to the head end sampling current and the tail end sampling current;
the system further comprises:
the sampling time correction unit is used for synchronizing the sampling time of the head end differential protection device and the tail end differential protection device once every second set time interval;
wherein, the synchronization unit specifically includes:
the command sending subunit is used for sending a synchronous command to the tail end differential protection device by the head end differential protection device;
the interruption opening subunit is used for opening the PCA interruption after the terminal differential protection device receives the synchronous instruction;
and the sampling time synchronization subunit is used for sending the synchronization pulse to a PCA (principal component analysis) interrupt pin of the tail end differential protection device by the head end differential protection device to generate interrupt, and synchronizing the sampling time.
5. The system of claim 4, further comprising:
the head end sampling current processing unit is used for calculating a real part and an imaginary part of the head end sampling current by adopting a window recursive Fourier algorithm and marking sampling point numbers;
and the tail end sampling current processing unit is used for calculating a real part and an imaginary part of the tail end sampling current by adopting a window recursive Fourier algorithm and marking the number of an upper sampling point.
6. The system according to claim 4, wherein the head-end fault determination unit specifically comprises:
the head end differential current calculating subunit is used for calculating the differential current between the head end sampling current and the tail end sampling current at the same moment;
the head end differential current judging subunit is used for judging whether the differential current exceeds a set value;
the head end fault determining subunit is used for determining that the line of the jurisdiction section has a fault when the differential current exceeds a set value;
the terminal fault determination unit specifically includes:
the tail end differential current calculating subunit is used for calculating the differential current between the head end sampling current and the tail end sampling current at the same moment;
a terminal difference current judgment subunit for judging whether the difference current exceeds a set value;
and the tail end fault determining subunit is used for determining that the line of the jurisdiction section has a fault when the difference current exceeds a set value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810581368.XA CN108666990B (en) | 2018-06-07 | 2018-06-07 | Power grid differential protection method and system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810581368.XA CN108666990B (en) | 2018-06-07 | 2018-06-07 | Power grid differential protection method and system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108666990A CN108666990A (en) | 2018-10-16 |
| CN108666990B true CN108666990B (en) | 2020-03-31 |
Family
ID=63775631
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810581368.XA Active CN108666990B (en) | 2018-06-07 | 2018-06-07 | Power grid differential protection method and system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108666990B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110649579A (en) * | 2019-09-29 | 2020-01-03 | 许继集团有限公司 | Differential protection method and device based on wireless communication |
| CN111697541B (en) * | 2020-04-30 | 2022-08-23 | 国网江苏省电力有限公司电力科学研究院 | Power distribution network line current differential protection synchronization method and system |
| CN114126028B (en) * | 2020-08-28 | 2024-06-11 | 宸芯科技股份有限公司 | Differential protection method, differential protection device, communication unit and storage medium |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102623966A (en) * | 2012-04-01 | 2012-08-01 | 许继集团有限公司 | Differential protection method for bus |
| CN105896489A (en) * | 2016-05-11 | 2016-08-24 | 许继集团有限公司 | Differential protection method and system for multi-end T connected transmission line |
| CN107276053A (en) * | 2017-07-13 | 2017-10-20 | 天津凯发电气股份有限公司 | A kind of equipment for protecting optical fibre longitudinal difference and method of data synchronization |
| CN108008676A (en) * | 2017-11-29 | 2018-05-08 | 西电通用电气自动化有限公司 | A kind of multiplied unit relay protection system and its synchronous method |
| CN108054740A (en) * | 2017-12-22 | 2018-05-18 | 南京因泰莱电器股份有限公司 | A kind of T-shaped patching fibers longitudinal difference protection method of data synchronization |
-
2018
- 2018-06-07 CN CN201810581368.XA patent/CN108666990B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102623966A (en) * | 2012-04-01 | 2012-08-01 | 许继集团有限公司 | Differential protection method for bus |
| CN105896489A (en) * | 2016-05-11 | 2016-08-24 | 许继集团有限公司 | Differential protection method and system for multi-end T connected transmission line |
| CN107276053A (en) * | 2017-07-13 | 2017-10-20 | 天津凯发电气股份有限公司 | A kind of equipment for protecting optical fibre longitudinal difference and method of data synchronization |
| CN108008676A (en) * | 2017-11-29 | 2018-05-08 | 西电通用电气自动化有限公司 | A kind of multiplied unit relay protection system and its synchronous method |
| CN108054740A (en) * | 2017-12-22 | 2018-05-18 | 南京因泰莱电器股份有限公司 | A kind of T-shaped patching fibers longitudinal difference protection method of data synchronization |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108666990A (en) | 2018-10-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103605023B (en) | A kind of combining unit time response measuring method and measurement apparatus | |
| CN108666990B (en) | Power grid differential protection method and system | |
| CN101874229B (en) | Method and system for registering events in wind turbines of a wind power system | |
| CN109286459B (en) | Time synchronization method and system | |
| WO2012075881A1 (en) | Ieee1588-based sampled value multi-interface synchronization system for multiple slave clocks | |
| CN109683567B (en) | RS485 network-based system clock synchronization method | |
| CN103823361B (en) | Multi-source dynamic self-adapting clock synchronizing method and device | |
| CN103546267A (en) | Time synchronization monitoring method and system | |
| CN109150357A (en) | The method for synchronizing time of hybrid bus based on RS485 and Ethernet | |
| CN103368137A (en) | Multi-terminal self-repairing data synchronization differential protection method based on network self-repairing | |
| Della Giustina et al. | Experimental characterization of time synchronization over a heterogeneous network for smart grids | |
| CN109407752B (en) | GIS breaker online monitoring system for realizing clock synchronization in RS485 communication | |
| CN109474362A (en) | Site protects sampled data adaptive synchronicity method and site to protect handset | |
| CN104215859B (en) | Satellite electronic load testing method | |
| CN103812731A (en) | Digitization sampling time delay frequency conversion measuring method and measuring system | |
| CN111697541B (en) | Power distribution network line current differential protection synchronization method and system | |
| CN210803591U (en) | High-precision synchronous acquisition device for monitoring extra-high voltage converter station sleeve | |
| CN109709422B (en) | Clock drift elimination method and device | |
| CN116244901A (en) | Electric power system model joint simulation method based on synchronous phasor measurement device | |
| CN208257398U (en) | A kind of power grid differential protection | |
| CN114726471A (en) | Power distribution field domain network clock accurate synchronization method and device based on HPLC | |
| CN107483291B (en) | Optical fiber longitudinal differential time synchronization method | |
| CN114584245B (en) | Multi-equipment synchronization method and system for traditional Chinese medicine | |
| Li et al. | The application of precision clock synchronization technology based on PTP (IEEE1588) in traveling wave fault location system | |
| CN108512204A (en) | A kind of power grid differential protection |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |