CN116169646A - Bus protection method and system based on current sampling value - Google Patents
Bus protection method and system based on current sampling value Download PDFInfo
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- CN116169646A CN116169646A CN202211137833.3A CN202211137833A CN116169646A CN 116169646 A CN116169646 A CN 116169646A CN 202211137833 A CN202211137833 A CN 202211137833A CN 116169646 A CN116169646 A CN 116169646A
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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
- H02H7/22—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 for distribution gear, e.g. bus-bar systems; for switching devices
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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
- G01R19/0038—Circuits for comparing several input signals and for indicating the result of this comparison, e.g. equal, different, greater, smaller (comparing pulses or pulse trains according to amplitude)
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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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- 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
- G01R19/14—Indicating direction of current; Indicating polarity of voltage
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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
- G01R19/30—Measuring the maximum or the minimum value of current or voltage reached in a time interval
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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Abstract
The invention discloses a bus protection method and a bus protection system based on a current sampling value, wherein the bus protection method comprises the following steps: when the starting element meets a preset starting criterion and is started, current grouping is carried out on the basis of current abrupt change value sampling values of each side of the electric element at each sampling moment, and a first current abrupt change value and a second current abrupt change value corresponding to each sampling moment are determined; performing polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time; performing point-by-point integration based on the first current abrupt change conversion value and the second current abrupt change conversion value corresponding to each sampling moment to obtain a first integral value and a second integral value; and determining the fault type according to a preset bus protection criterion based on the first integral value and the second integral value, so as to perform bus protection based on the determined fault type.
Description
Technical Field
The invention relates to the technical field of relay protection of power systems, in particular to a bus protection method based on a current sampling value.
Background
And a bus in the transformer substation is connected with a circuit and a transformer, so that the influence range of bus faults is large, and the fault bus needs to be rapidly cut off by bus protection. The existing bus protection mostly adopts the principle of industrial frequency differential motion protection, and the action speed of protection is limited by a fixed sampling data window. In recent years, a large number of new energy sources are connected into an alternating current power grid, after an alternating current system fails, short circuit current provided by the new energy sources is influenced by a control strategy, the amplitude of the failure current is rapidly reduced, and the rapidity and the sensitivity of bus protection are seriously influenced.
In addition, the protection principle based on transient state quantity is mainly used for fault identification by adopting the wave head characteristics of traveling waves or transient state energy of different frequency bands on a frequency domain, but the sampling rate is high, the calculation amount of a mathematical algorithm for extracting the transient state component is large, the protection action performance is limited by various factors such as fault time, transition resistance and the like, and the protection reliability is required to be further improved.
Disclosure of Invention
The invention provides a bus protection method and system based on a current sampling value, which are used for solving the problem of how to quickly and accurately identify bus faults.
In order to solve the above problems, according to an aspect of the present invention, there is provided a bus bar protection method based on a current sampling value, the method comprising:
When the starting element meets a preset starting criterion and is started, current grouping is carried out on the basis of current abrupt change value sampling values of each side of the electric element at each sampling moment, and a first current abrupt change value and a second current abrupt change value corresponding to each sampling moment are determined;
performing polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time;
performing point-by-point integration based on the first current abrupt change conversion value and the second current abrupt change conversion value corresponding to each sampling moment to obtain a first integral value and a second integral value;
and determining the fault type according to a preset bus protection criterion based on the first integral value and the second integral value, so as to perform bus protection based on the determined fault type.
Preferably, the determining the first current mutation amount and the second current mutation amount corresponding to each sampling time based on the current mutation amount sampling values of each side of the electrical element at each sampling time includes:
for any sampling time, selecting the current abrupt change sampling value with the largest amplitude in the current abrupt change sampling values of all sides of the electric element at the any sampling time as the first current abrupt change delta i corresponding to the any sampling time m (t)＝max(|Δi 1 (t)|,|Δi 2 (t)|,…,|Δi h (t) |); determining a second current abrupt change delta i corresponding to any sampling moment according to the difference value between the sum of the current abrupt change sampling values of each side of the electric element at any sampling moment and the first current abrupt change n (t)＝Δi Σ (t)-Δi m (t)；
Wherein, |Δi h (t) is the amplitude of the current abrupt change sampling value at the sampling time t at the h side; Δi Σ And (t) is the sum of current mutation sampling values of each side of the electric element at the sampling time t.
Preferably, the performing polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time includes:
for any sampling time, if the first current abrupt change delta i corresponding to any sampling time t m If the polarity of (t) is negative, determining Δi M (t)＝-Δi m (t)，Δi N (t)＝-Δi n (t); otherwise, determining Δi M (t)＝Δi m (t),Δi N (t)＝Δi n (t); wherein Δi n (t) is the sampling timet corresponds to a second current abrupt change; Δi M (t) and Δi N (t) the first current abrupt change value and the second current abrupt change value, respectively.
Preferably, the determining the fault type according to a preset bus protection criterion based on the first integral value and the second integral value includes:
If the first current abrupt change conversion value and the second current abrupt change conversion value meet a preset bus protection criterion, determining that the fault type is a fault in a bus area; otherwise, determining the fault type as the fault outside the bus area;
the bus protection criterion is preset, and the bus protection criterion comprises:
wherein ΣΔi M (t) and ΣΔi N (t) a first current-abrupt change-over value and a second current-abrupt change-over value, respectively; i e Is the rated current of the bus bar protection device.
Preferably, wherein the method further comprises:
when the starting element meets the first preset promoter criterion or the second preset promoter criterion, determining that the starting element meets the preset starting criterion;
wherein the first preset promoter criterion comprises:
Δf 1 (t)＝f 1 (t)-f 1 (t-T/4)>f 1.set ，
the second preset promoter criterion comprises:
Δf 2 (t)＝f 2 (t)-f 2 (t-T/4)>f 2.set ，
wherein Δf 1 (t) is a first variation; Δf 2 (t) is a second variation; f (f) 1 (t) is first data at time t; f (f) 2 (t) is second data at time t; f (f) 1 (T-T/4) is f before quarter cycle 1 (t)；f 2 (T-T/4) is f before quarter cycle 2 (t)；f 1.set A first preset threshold value; f (f) 2.set Is a second predetermined threshold.
Preferably, wherein the method further comprises:
calculating abrupt change delta i of each branch current sampling value of bus based on each branch current sampling value of bus φ.k (t) comprising:
Δi φ.k (t)＝i φ.k (t)-i φ.k (t-T s )，
calculating differential current i of each phase based on mutation amount of current sampling value of each branch φ.Σ (t) comprising:
calculating first data based on each phase difference stream, comprising:
f 1 (t)＝(i a.Σ (t)-i b.Σ (t)) 2 +(i b.Σ (t)-i c.Σ (t)) 2 +(i c.Σ (t)-i a.Σ (t) 2 ，
wherein i is φ.k (t) is the current sampling value of phi phase k branch at t time, phi is A, B, C, i φ.k (t-T s ) T-T being the kth branch of phi phase s Current sample value at moment, T s The time corresponding to the one-cycle wave; n is the number of branches; f (f) 1 (t) is first data; i.e a.Σ (t)、i b.Σ (t) and i c.Σ (t) is the differential flow of three phases A, B, C at time t respectively;
dividing the current of each branch of the bus into two groups, comparing the mutation amounts of the current sampling values of all branches, and determining the branch current delta i with the maximum mutation amount of the current sampling value φ.max (t)，Δi φ.max (t)＝max(Δi φ.1 (t),Δi φ.2 (t)，…，Δi φ.k (t))；
Calculate the division Δi φ.max (t) the sum Δi of the abrupt amounts of the current sampling values of the other branches outside the corresponding branch φ.s (t)，Δi φ.s (t)＝i φ.Σ (t)-Δi φ.max (t)；
Based on i φ.s (t) calculating second data comprises:
f 2 (t)＝(i a.s (t)-i b.s (t)) 2 +(i b.s (t)-i c.s (t)) 2 +(i c.s (t)-i a.s (t)) 2 ，
wherein Δi φ.k (t) is a current sampling value of the kth branch of phi phase at the moment t, and phi is A, B, C; i.e φ.Σ (t) is the sum of the current sample values of all branches of phi phase; f (f) 2 (t) is second data.
According to another aspect of the present invention, there is provided a bus bar protection system based on current sampling values, the system comprising:
the current abrupt change determining unit is used for grouping currents based on current abrupt change sampling values of each side of the electric element at each sampling moment when the starting element meets a preset starting criterion and determining a first current abrupt change and a second current abrupt change corresponding to each sampling moment;
The polarity conversion unit is used for respectively carrying out polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time so as to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time;
the integration unit is used for carrying out point-to-point integration based on the first current mutation amount conversion value and the second current mutation amount conversion value corresponding to each sampling time to obtain a first integration value and a second integration value;
and the bus protection unit is used for determining the fault type according to a preset bus protection criterion based on the first integral value and the second integral value so as to conduct bus protection based on the determined fault type.
Preferably, the current abrupt change amount determining unit performs current grouping based on current abrupt change amount sampling values of each side of the electric element at each sampling time, and determines a first current abrupt change amount and a second current abrupt change amount corresponding to each sampling time, including:
for any sampling time, each side of the electrical element is selected at the sampling timeThe current abrupt change sampling value with the largest amplitude in the current abrupt change sampling values is the first current abrupt change delta i corresponding to any sampling time m (t)＝max(|Δi 1 (t)|,|Δi 2 (t)|,…,|Δi h (t) |); determining a second current abrupt change delta i corresponding to any sampling moment according to the difference value between the sum of the current abrupt change sampling values of each side of the electric element at any sampling moment and the first current abrupt change n (t)＝Δi Σ (t)-Δi m (t)；
Wherein, |Δi h (t) is the amplitude of the current abrupt change sampling value at the sampling time t at the h side; Δi Σ And (t) is the sum of current mutation sampling values of each side of the electric element at the sampling time t.
Preferably, the polarity conversion unit performs polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time, so as to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time, and the polarity conversion unit includes:
for any sampling time, if the first current abrupt change delta i corresponding to any sampling time t m If the polarity of (t) is negative, determining Δi M (t)＝-Δi m (t)，Δi N (t)＝-Δi n (t); otherwise, determining Δi M (t)＝Δi m (t),Δi N (t)＝Δi n (t); wherein Δi n (t) is a second current abrupt change amount corresponding to the sampling time t; Δi M (t) and Δi N (t) the first current abrupt change value and the second current abrupt change value, respectively.
Preferably, the bus protection unit determines the fault type according to a preset bus protection criterion based on the first integrated value and the second integrated value, and includes:
If the first current abrupt change conversion value and the second current abrupt change conversion value meet a preset bus protection criterion, determining that the fault type is a fault in a bus area; otherwise, determining the fault type as the fault outside the bus area;
the bus protection criterion is preset, and the bus protection criterion comprises:
wherein ΣΔi M (t) and ΣΔi N (t) a first current-abrupt change-over value and a second current-abrupt change-over value, respectively; i e Is the rated current of the bus bar protection device.
Preferably, wherein the system further comprises:
the starting judgment unit is used for determining that the starting element meets the preset starting criterion when the starting element meets the first preset promoter criterion or the second preset promoter criterion;
wherein the first preset promoter criterion comprises:
Δf 1 (t)＝f 1 (t)-f 1 (t-T/4)>f 1.set ，
the second preset promoter criterion comprises:
Δf 2 (t)＝f 2 (t)-f 2 (t-T/4)>f 2.set ，
wherein Δf 1 (t) is a first variation; Δf 2 (t) is a second variation; f (f) 1 (t) is first data at time t; f (f) 2 (t) is second data at time t; f (f) 1 (T-T/4) is f before quarter cycle 1 (t)；f 2 (T-T/4) is f before quarter cycle 2 (t)；f 1.set A first preset threshold value; f (f) 2.set Is a second predetermined threshold.
Preferably, the start-up judging unit further includes:
Calculating abrupt change delta i of each branch current sampling value of bus based on each branch current sampling value of bus φ.k (t) comprising:
Δi φ.k (t)＝i φ.k (t)-i φ.k (t-T s )，
calculating differential current i of each phase based on mutation amount of current sampling value of each branch φ.Σ (t) comprising:
calculating first data based on each phase difference stream, comprising:
f 1 (t)＝(i a.Σ (t)-i b.Σ (t)) 2 +(i b.Σ (t)-i c.Σ (t)) 2 +(i c.Σ (t)-i a.Σ (t) 2 ，
wherein i is φ.k (t) is the current sampling value of phi phase k branch at t time, phi is A, B, C, i φ.k (t-T s ) T-T being the kth branch of phi phase s Current sample value at moment, T s The time corresponding to the one-cycle wave; n is the number of branches; f (f) 1 (t) is first data; i.e a.Σ (t)、i b.Σ (t) and i c . Σ (t) is the differential flow of three phases A, B, C at time t respectively;
dividing the current of each branch of the bus into two groups, comparing the mutation amounts of the current sampling values of all branches, and determining the branch current delta i with the maximum mutation amount of the current sampling value φ.max (t)，Δi φ.max (t)＝max(Δi φ . 1 (t),Δi φ.2 (t)，…，Δi φ.k (t))；
Calculate the division Δi φ.max (t) the sum Δi of the abrupt amounts of the current sampling values of the other branches outside the corresponding branch φ . s (t)，Δi φ.s (t)＝i φ.Σ (t)-Δi φ.max (t)；
Based on i φ.s (t) calculating second data comprises:
f 2 (t)＝(i a.s (t)-i b.s (t)) 2 +(i b.s (t)-i c.s (t)) 2 +(i c.s (t)-i a.s (t)) 2 ，
wherein Δi φ.k (t) is a current sampling value of the kth branch of phi phase at the moment t, and phi is A, B, C; i.e φ.Σ (t) is the sum of the current sample values of all branches of phi phase; f (f) 2 (t) is second data.
The invention provides a bus protection method and system based on a current sampling value, comprising the following steps: when the starting element meets a preset starting criterion and is started, current grouping is carried out on the basis of current abrupt change value sampling values of each side of the electric element at each sampling moment, and a first current abrupt change value and a second current abrupt change value corresponding to each sampling moment are determined; performing polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time; performing point-by-point integration based on the first current abrupt change conversion value and the second current abrupt change conversion value corresponding to each sampling moment to obtain a first integral value and a second integral value; and determining the fault type according to a preset bus protection criterion based on the first integral value and the second integral value, so as to perform bus protection based on the determined fault type. The starting element is responsible for detecting the occurrence time of faults, the protection element is responsible for identifying internal and external faults of a bus area, the sudden change characteristics of the current after the faults can be extracted rapidly by utilizing the current sampling values of three phases at the same time, the sudden change amount of the current sampling values of multiple branches of the bus and the starting element and the sudden change amount of the grouping current sampling values are constructed by utilizing the current sampling values of multiple branches of the bus, the occurrence time of the internal and external faults of the bus area is detected rapidly according to the action behaviors and time sequences of the two starting elements, the current of the multiple branches is divided into two groups according to the characteristics of the current sampling values of the multiple branches in the internal and external faults of the bus area, the motion trail of the current sampling values after the faults is visually reflected on the plane through the polarity conversion, the sampling value integration and other data processing, and the bus faults are identified rapidly and accurately through dividing the internal and external fault identification areas of the bus.
Drawings
Exemplary embodiments of the present invention may be more completely understood in consideration of the following drawings:
FIG. 1 is a flow chart of a current sample value based bus bar protection method 100 according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a bus bar in-zone fault and out-of-zone fault identification zone according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a bus fault simulation model according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of current waveforms for each branch of a fault bus in a zone according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of the result of an action of a fault bus initiation element within a zone according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of an in-zone fault bus protection action scenario in accordance with an embodiment of the present invention;
FIG. 7 is a schematic diagram of current waveforms for each branch of an out-of-zone fault bus according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of the operation of an out-of-zone fault bus initiation element according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of an out-of-zone fault bus protection action scenario in accordance with an embodiment of the present invention;
FIG. 10 is a schematic diagram of current waveforms of each branch of a bus at the time of an out-of-zone fault to an in-zone fault according to an embodiment of the present invention;
FIG. 11 is a schematic diagram of the operation of the out-of-zone fault to in-zone fault bus initiation element according to an embodiment of the present invention;
FIG. 12 is a schematic diagram of an out-of-zone fault to in-zone fault bus protection action scenario in accordance with an embodiment of the present invention;
fig. 13 is a schematic structural diagram of a bus bar protection system 1300 based on current sampling values according to an embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the examples described herein, which are provided to fully and completely disclose the present invention and fully convey the scope of the invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like elements/components are referred to by like reference numerals.
Unless otherwise indicated, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, it will be understood that terms defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flow chart of a bus bar protection method 100 based on current sample values according to an embodiment of the present invention. As shown in fig. 1, in the bus protection method based on current sampling values provided in the embodiment of the invention, a starting element is responsible for detecting the occurrence time of faults, a protection element is responsible for identifying internal faults and external faults of a bus area, the sudden change characteristics of current after faults can be rapidly extracted by using three-phase current sampling values at the same time, multiple-branch current sampling value sudden change amounts of the multiple-branch current sampling values and starting elements and grouping current sampling value sudden change starting elements are constructed by using bus multiple-branch current sampling values, the occurrence time of internal faults and external faults of the bus area are rapidly detected according to the action behaviors and time sequences of the two starting elements, then the multiple-branch current is divided into two groups according to the characteristics of the multiple-branch current sampling values in the internal faults and the external faults of the bus area, the motion trail of the current sampling values after faults is intuitively reflected on the plane through data processing such as polarity conversion and sampling value integration, and the bus fault identification area is rapidly and accurately identified through dividing the internal faults and external faults. Starting from step 101, when a starting element meets a preset starting criterion and starts in step 101, current grouping is performed based on current mutation value sampling values of each sampling time on each side of an electric element, and a first current mutation value and a second current mutation value corresponding to each sampling time are determined.
Preferably, wherein the method further comprises:
when the starting element meets the first preset promoter criterion or the second preset promoter criterion, determining that the starting element meets the preset starting criterion;
wherein the first preset promoter criterion comprises:
Δf 1 (t)＝f 1 (t)-f 1 (t-T/4)>f 1.set ，
the second preset promoter criterion comprises:
Δf 2 (t)＝f 2 (t)-f 2 (t-T/4)>f 2.set ，
wherein Δf 1 (t) is a first variation; Δf 2 (t) is a second variation; f (f) 1 (t) is first data at time t; f (f) 2 (t) is second data at time t; f (f) 1 (T-T/4) is f before quarter cycle 1 (t)；f 2 (T-T/4) is f before quarter cycle 2 (t)；f 1.set A first preset threshold value; f (f) 2.set Is a second predetermined threshold.
Preferably, wherein the method further comprises:
calculating abrupt change delta i of each branch current sampling value of bus based on each branch current sampling value of bus φ.k (t) comprising:
Δi φ.k (t)＝i φ.k (t)-i φ.k (t-T s )，
calculating differential current i of each phase based on mutation amount of current sampling value of each branch φ.Σ (t) comprising:
calculating first data based on each phase difference stream, comprising:
f 1 (t)＝(i a.Σ (t)-i b.Σ (t)) 2 +(i b.Σ (t)-i c.Σ (t)) 2 +(i c.Σ (t)-i a.Σ (t) 2 ，
wherein i is φ.k (t) is the current sampling value of phi phase k branch at t time, phi is A, B, C, i φ.k (t-T s ) T-T being the kth branch of phi phase s Current sample value at moment, T s The time corresponding to the one-cycle wave; n is the number of branches; f (f) 1 (t) is first data; i.e a.Σ (t)、i b.Σ (t) and i c . Σ (t) is the differential flow of three phases A, B, C at time t respectively;
dividing the current of each branch of the bus into two groups, comparing the mutation amounts of the current sampling values of all branches, and determining the branch current delta i with the maximum mutation amount of the current sampling value φ.max (t)，Δi φ.max (t)＝max(Δi φ.1 (t),Δi φ.2 (t)，…，Δi φ.k (t))；
Calculate the division Δi φ.max (t) the sum Δi of the abrupt amounts of the current sampling values of the other branches outside the corresponding branch φ.s (t)，Δi φ.s (t)＝i φ.Σ (t)-Δi φ.max (t)；
Based on i φ.s (t) calculating second data comprises:
f 2 (t)＝(i a.s (t)-i b.s (t)) 2 +(i b.s (t)-i c.s (t)) 2 +(i c.s (t)-i a.s (t)) 2 ，
wherein Δi φ.k (t) is a current sampling value of the kth branch of phi phase at the moment t, and phi is A, B, C; i.e φ.Σ (t) is the sum of the current sample values of all branches of phi phase; f (f) 2 (t) is second data.
Preferably, the determining the first current mutation amount and the second current mutation amount corresponding to each sampling time based on the current mutation amount sampling values of each side of the electrical element at each sampling time includes:
for any sampling time, selecting the current abrupt change sampling value with the largest amplitude in the current abrupt change sampling values of all sides of the electric element at the any sampling time as the first current abrupt change delta i corresponding to the any sampling time m (t)＝max(|Δi 1 (t)|,|Δi 2 (t)|,…,|Δi h (t) |); determining a second current abrupt change delta i corresponding to any sampling moment according to the difference value between the sum of the current abrupt change sampling values of each side of the electric element at any sampling moment and the first current abrupt change n (t)＝Δi Σ (t)-Δi m (t)；
Wherein, |Δi h (t) is the amplitude of the current abrupt change sampling value at the sampling time t at the h side; Δi Σ (t) sampling the electrical component on each sideThe sum of the current burst value samples at time t.
The invention utilizes the busbar protection of the current abrupt change sampling value track characteristic to realize based on a starting element and a protection element. The starting element comprises a multi-branch current sampling value abrupt change quantity and a starting element, and a grouping current sampling value abrupt change quantity starting element.
(1) Principle of abrupt change of sampling value and starting element of multi-branch current
And constructing a fault starting element in the area by utilizing the abrupt change of the current sampling value of each branch of the bus.
Firstly, calculating the abrupt change delta i of the current sampling value of each branch of the bus φ.k (t)，
Δi φ.k (t)＝i φ.k (t)-i φ.k (t-T s ) (1)
Wherein i is φ.k (t) is the current sampling value of phi phase k branch at t time, phi is A, B, C, i φ.k (t-T s ) T-T being the kth branch of phi phase s Current sample value at moment, T s Is the corresponding time of a cycle wave (20 ms).
Calculating each phase difference stream i by using mutation quantity of current sampling value of each branch φ.Σ (t)，
Will i φ.Σ (t) substituting f (t) to obtain
f 1 (t)＝(i a.Σ (t)-i b.Σ (t)) 2 +(i b.Σ (t)-i c.Σ (t)) 2 +(i c.Σ (t)-i a.Σ (t) 2 (3)
The abrupt change amount of the multi-branch current sampling value and the starting criterion I (namely a first preset promoter criterion) are as follows:
Δf 1 (t)＝f 1 (t)-f 1 (t-T/4)>f 1.set (4)
wherein f 1 (T-T/4) is f before one quarter cycle (5 ms) 1 (t)，f 1.set Is fixed for action, and f 1.set ＝f 1. Floating device +f 1. Fixing ，f 1. Floating device For floating threshold, the value is T E [ T-T, T-T/2 ]]Δf in between 1 (t) maximum value. f (f) 1. Fixing Is a fixed threshold.
(2) Principle of grouping current sampling value abrupt change starting element
Firstly, dividing the current of each branch of a bus into two groups, comparing the mutation amounts of current sampling values of all branches, and extracting the branch current delta i with the largest mutation amount of the current sampling values φ.max (t)。
Δi φ.max (t)＝max(Δi φ.1 (t),Δi φ.2 (t)…Δi φ.k (t)) (5)
Let Δi φ.max (t) corresponding branch currents are one group, and the mutation amounts of the sampling values of the rest branch currents are summed to form another group delta i φ.s (t) obtainable according to formula (2),
Δi φ.s (t)＝i φ.Σ (t)-Δi φ.max (t) (6)
will i φ.s (t) substituting f (t) to obtain
f 2 (t)＝(i a.s (t)-i b.s (t)) 2 +(i b.s (t)-i c.s (t)) 2 +(i c.s (t)-i a.s (t)) 2 (7)
The grouping current sampling value mutation quantity starting criterion II (namely a second preset promoter criterion) is as follows:
Δf 2 (t)＝f 2 (t)-f 2 (t-T/4)>f 2.set (8)
wherein f 2 (T-T/4) is f before one quarter cycle (5 ms) 2 (t)，f 2.set Is fixed for action, and f 2.set ＝f 2. Floating device +f 2. Fixing ，f 2. Floating device For floating threshold, the value is Deltaf 2 (T) at t.epsilon.t-T, T-T/2]Maximum value between. f (f) 2. Fixing Is a fixed threshold.
In the invention, when the abrupt change of the multi-branch current sampling value and the starting element meet a first preset starting criterion or the abrupt change of the grouping current sampling value meets a second preset starting criterion, the starting element is determined to meet the preset starting criterion, at the moment, the bus can be determined to have faults, but the fault type cannot be determined, at the moment, the starting element is started, and the protection element is triggered to execute bus protection, so that the fault type is determined.
Specifically, the current grouping is performed first. Specifically, comparing the sampled value amplitude of the current abrupt change at each sampling time of each side of the electric element, and selecting a maximum amplitude branch max (|Δi) 1 (t)|,|Δi 2 (t)|,…,|Δi h (t) |), let Δi m (t) sampling the current mutation of the branch with the maximum amplitude, and adding delta i to the current mutation m (t) as a first current argument, the remaining branch current sample value arguments are summed to Δi n (t)＝Δi Σ (t)-Δi m (t) adding Δi to the reaction mixture n (t) as a second current abrupt amount; wherein, |Δi h (t) is the amplitude of the current abrupt change sampling value at the sampling time t at the h side; Δi Σ And (t) is the sum of current mutation sampling values of each side of the electric element at the sampling time t.
In step 102, the polarity of the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time are respectively converted to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time.
Preferably, the performing polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time includes:
for any sampling time, if the first current abrupt change delta i corresponding to any sampling time t m If the polarity of (t) is negative, determining Δi M (t)＝-Δi m (t)，Δi N (t)＝-Δi n (t); otherwise, determining Δi M (t)＝Δi m (t),Δi N (t)＝Δi n (t); wherein Δi n (t) is a second current abrupt change amount corresponding to the sampling time t; Δi M (t) and Δi N (t) the first current abrupt change value and the second current abrupt change value, respectively.
In step 103, point-by-point integration is performed based on the first current abrupt change conversion value and the second current abrupt change conversion value corresponding to each sampling time, and a first integrated value and a second integrated value are obtained.
In step 104, a fault type is determined according to a preset bus protection criterion based on the first integral value and the second integral value, so as to perform bus protection based on the determined fault type.
Preferably, the determining the fault type according to a preset bus protection criterion based on the first integral value and the second integral value includes:
if the first current abrupt change conversion value and the second current abrupt change conversion value meet a preset bus protection criterion, determining that the fault type is a fault in a bus area; otherwise, determining the fault type as the fault outside the bus area;
the bus protection criterion is preset, and the bus protection criterion comprises:
wherein ΣΔi M (t) and ΣΔi N (t) a first current-abrupt change-over value and a second current-abrupt change-over value, respectively; i e Is the rated current of the bus bar protection device.
In the present invention, after completing the current grouping, polarity conversion is performed, including: analysis of the first processed (. DELTA.i) m (t)，Δi n (t)) if Δi m (t) polarity "-", let Δi M (t)＝-Δi m (t),Δi N (t)＝-Δi n (t) if Δi m (t) polarity "+", let Δi M (t)＝Δi m (t),Δi N (t)＝Δi n (t). After polarity conversion, sample value integration is performed, including: the data (Δi) obtained after the polarity conversion is converted M (t)，Δi N (t)) is subjected to point-by-point integration to obtain (ΣΔi) M (t)，ΣΔi N (t)). Finally, determining ΣΔi M (t) and ΣΔi N And (t) whether the bus protection criterion is met, if so, determining that the internal faults of the bus area occur, otherwise, determining that the external faults occur. The principle of judging the faults inside and outside the zone is shown in fig. 2.
Wherein, bus protection criterion is:
wherein ΣΔi M (t) and ΣΔi N (t) a first current-abrupt change-over value and a second current-abrupt change-over value, respectively; i e Is the rated current of the bus bar protection device.
In the invention, f when the bus bar fails in the zone 1 (t-T/4)＝0，f 1 (t)>0，Δf 1 (t)>f 1.set The criterion I is satisfied. f (f) 2 (T-T/4) is a fixed value, f 2 (t) superimposing the 100Hz component, Δf, to a fixed value 2 (t)>f 2.set Criterion II is satisfied.
F when the bus fails outside the area 1 (t-T/4)＝0，f 1 (t)＝0，Δf 1 (t)<f 1.set The criterion I is not satisfied. f (f) 2 (T-T/4) is a fixed value, f 2 (t) superimposing the 100Hz component, Δf, to a fixed value 2 (t)>f 2.set Criterion II is satisfied.
When the bus generates a fault in the external fault transfer area, the time of the external fault of the bus area is not satisfied, and the criterion I is satisfied; the fault time in the bus area is satisfied by both criteria I and II.
And for the protection element, through data preprocessing, firstly, the internal and external faults are concentrated in the 90-degree interval range of the first quadrant and the second quadrant, so that the internal and external faults can be conveniently identified. Secondly, the monotonic change characteristics of the currents in the internal and external fault processes can be intuitively displayed through the track of the integration value of the abrupt variable current sampling values in the fault period.
And when the bus area fails, the operation track of the integrated value of the current mutation sampling value rapidly enters an out-of-area failure recognition area of the second quadrant from the original point, so that the out-of-area failure is accurately recognized, and the correct and non-action is protected.
When the faults occur in the bus area, the operation track of the integrated value of the current mutation quantity sampling value rapidly enters the fault identification area in the area of the first quadrant from the original point, so that the faults in the area are accurately identified, and correct actions are protected.
When the bus generates an out-of-zone fault to an in-zone fault, after the out-of-zone fault, the operation track of the integrated value of the current mutation value rapidly enters an out-of-zone fault identification zone of the second quadrant from the original point, so that the out-of-zone fault is accurately identified, and the correct and non-action is protected. When the fault develops into an in-area fault, the operation track of the integrated value of the current mutation sampling value rapidly enters the in-area fault identification area from the out-area fault identification area, accurately identifies the in-area fault and cuts off a fault bus.
The following specifically exemplifies embodiments of the present invention
The simulation model is shown in fig. 3, wherein S1 is a wind field, the capacity is 250MW, S2-S4 are conventional alternating current systems, B1 is a bus, F1 is a fault point in a bus area, and F2 is a fault point outside the bus area.
(1) Failure in a zone
When the bus is in an A-phase grounding fault at the point F1, the primary value of fault phase current of each branch of the bus B1 is shown as in fig. 4, and it can be seen that the short-circuit current provided by the wind farm is the smallest (branch 1) and the current phases of the branches 2-4 are the same.
When the bus area fails, the action condition of the starting element criterion provided by the patent is shown in fig. 5, a red curve in the diagram is a starting element fixed value, and therefore, when the bus area fails, the criterion I, II acts 0.86ms after the failure (the first sampling value after the failure).
When the fault occurs in the busbar zone, the action track of the busbar protection criterion provided by the patent is shown in fig. 6, and after the fault, the operation track of the integrated value of the current mutation value rapidly enters the fault identification zone in the first quadrant from the origin, so that the fault in the zone is accurately identified.
(2) Out-of-zone failure
When the bus at the point F2 has an A-phase ground fault, the primary value of the fault phase current of each branch of the bus B1 is shown as in fig. 7, and it can be seen that the short-circuit current provided by the wind farm is the smallest (branch 1) during the out-of-zone fault, and the current phases of the branches 2 and 3 are opposite to the current phase of the branch 4.
When the bus area fails, the action condition of the starting element criterion provided by the patent is shown in fig. 8, a red curve in the diagram is a starting element fixed value, and it can be seen that when the bus fails outside the area, the criterion I does not act, and the criterion II acts 0.86ms after the failure (the first sampling value after the failure).
When the bus zone fails, the action track of the bus protection criterion provided by the patent is shown as a figure 9, and after the fault, the operation track of the integrated value of the current mutation value rapidly enters the out-of-zone fault identification zone of the second quadrant from the origin, so that the out-of-zone fault is accurately identified, and the correct and non-action is protected.
(3) Out-of-zone fault to in-zone fault
When the bus line F2 has an A-phase ground fault, the bus line F1 has an A-phase ground fault after the fault lasts for 80ms, the primary value of the fault phase current of each branch of the bus line B1 is shown in fig. 10, and the short circuit current provided by the wind farm is minimum (branch 1) during the fault period. When the fault occurs outside the area, the current phase of the branch circuits 2 and 3 is opposite to the current phase of the branch circuit 4; in the event of a fault in the zone, the current phases of the branches 2, 3 are identical.
When the bus fails outside the area and changes into the area, the action condition of the starting element criterion provided by the patent is shown in fig. 11, a red curve in the diagram is the fixed value of the starting element, and as can be seen, when the bus fails outside the area, the criterion I does not act, the criterion II acts after 0.86ms after the failure (the first sampling value after the failure), when the area fails, the criterion I acts after 0.86ms after the area, and meanwhile, the criterion II acts again.
When the bus generates the out-of-zone fault and changes into the in-zone fault, the action track of the bus protection criterion provided by the patent is shown as a figure 12, and the action track of the integrated value of the current mutation value rapidly enters the out-of-zone fault identification zone of the second quadrant from the origin after the out-of-zone fault, so that the out-of-zone fault is accurately identified, and the protection is correct and not actuated. When the fault develops into an in-area fault, the operation track of the integrated value of the current mutation sampling value rapidly enters the in-area fault identification area from the out-area fault identification area, accurately identifies the in-area fault and cuts off a fault bus.
Fig. 13 is a schematic structural diagram of a bus bar protection system 1300 based on current sampling values according to an embodiment of the present invention. As shown in fig. 13, a bus bar protection system 1300 based on current sampling values according to an embodiment of the present invention includes: a current abrupt amount determination unit 1301, a polarity conversion unit 1302, an integration unit 1303, and a bus bar protection unit 1304.
Preferably, the current abrupt change amount determining unit 1301 is configured to, when the starting element meets a preset starting criterion, perform current grouping based on current abrupt change amount sampling values of each side of the electrical element at each sampling time, and determine a first current abrupt change amount and a second current abrupt change amount corresponding to each sampling time.
Preferably, the current abrupt change amount determining unit 1301 performs current grouping based on current abrupt change amount sampling values of each side of the electrical element at each sampling time, and determines a first current abrupt change amount and a second current abrupt change amount corresponding to each sampling time, including:
for any sampling time, selecting the current abrupt change sampling value with the largest amplitude in the current abrupt change sampling values of all sides of the electric element at the any sampling time as the first current abrupt change delta i corresponding to the any sampling time m (t)＝max(|Δi 1 (t)|,|Δi 2 (t)|,…,|Δi h (t) |); determining a second current abrupt change delta i corresponding to any sampling moment according to the difference value between the sum of the current abrupt change sampling values of each side of the electric element at any sampling moment and the first current abrupt change n (t)＝Δi Σ (t)-Δi m (t)；
Wherein, |Δi h (t) is the amplitude of the current abrupt change sampling value at the sampling time t at the h side; Δi Σ And (t) is the sum of current mutation sampling values of each side of the electric element at the sampling time t.
Preferably, the polarity conversion unit 1302 is configured to perform polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time, so as to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time.
Preferably, the polarity conversion unit 1302 performs polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time, which includes:
for any sampling time, if the first current abrupt change delta i corresponding to any sampling time t m If the polarity of (t) is negative, determining Δi M (t)＝-Δi m (t)，Δi N (t)＝-Δi n (t); otherwise, determining Δi M (t)＝Δi m (t),Δi N (t)＝Δi n (t); wherein Δi n (t) is a second current abrupt change amount corresponding to the sampling time t; Δi M (t) and Δi N (t) the first current abrupt change value and the second current abrupt change value, respectively.
Preferably, the integrating unit 1303 is configured to perform point-by-point integration based on the first current abrupt change conversion value and the second current abrupt change conversion value corresponding to each sampling time, and obtain a first integrated value and a second integrated value.
Preferably, the bus protection unit 1304 is configured to determine a fault type according to a preset bus protection criterion based on the first integrated value and the second integrated value, so as to perform bus protection based on the determined fault type.
Preferably, the bus protection unit 1304, based on the first integral value and the second integral value, determines a fault type according to a preset bus protection criterion, including:
If the first current abrupt change conversion value and the second current abrupt change conversion value meet a preset bus protection criterion, determining that the fault type is a fault in a bus area; otherwise, determining the fault type as the fault outside the bus area;
the bus protection criterion is preset, and the bus protection criterion comprises:
wherein ΣΔi M (t) and ΣΔi N (t) a first current-abrupt change-over value and a second current-abrupt change-over value, respectively; i e Is the rated current of the bus bar protection device.
Preferably, wherein the system further comprises:
the starting judgment unit is used for determining that the starting element meets the preset starting criterion when the starting element meets the first preset promoter criterion or the second preset promoter criterion;
wherein the first preset promoter criterion comprises:
Δf 1 (t)＝f 1 (t)-f 1 (t-T/4)>f 1.set ，
the second preset promoter criterion comprises:
Δf 2 (t)＝f 2 (t)-f 2 (t-T/4)>f 2.set ，
wherein Δf 1 (t) is a first variation; Δf 2 (t) is a second variation; f (f) 1 (t) is first data at time t; f (f) 2 (t) is second data at time t; f (f) 1 (T-T/4) is f before quarter cycle 1 (t)；f 2 (T-T/4) is f before quarter cycle 2 (t)；f 1.set A first preset threshold value; f (f) 2.set Is a second predetermined threshold.
Preferably, the start-up judging unit further includes:
Calculating abrupt change delta i of each branch current sampling value of bus based on each branch current sampling value of bus φ.k (t) comprising:
Δi φ.k (t)＝i φ.k (t)-i φ.k (t-T s )，
calculating differential current i of each phase based on mutation amount of current sampling value of each branch φ.Σ (t) comprising:
calculating first data based on each phase difference stream, comprising:
f 1 (t)＝(i a.Σ (t)-i b.Σ (t)) 2 +(i b.Σ (t)-i c.Σ (t)) 2 +(i c.Σ (t)-i a.Σ (t) 2 ，
wherein i is φ.k (t) is the current sampling value of phi phase k branch at t time, phi is A, B, C, i φ.k (t-T s ) T-T being the kth branch of phi phase s Current sample value at moment, T s The time corresponding to the one-cycle wave; n is the number of branches; f (f) 1 (t) is first data; i.e a.Σ (t)、i b.Σ (t) and i c . Σ (t) is the differential flow of three phases A, B, C at time t respectively;
dividing the current of each branch of the bus into two groups, comparing the mutation amounts of the current sampling values of all branches, and determining the branch current delta i with the maximum mutation amount of the current sampling value φ.max (t)，Δi φ.max (t)＝max(Δi φ.1 (t),Δi φ.2 (t)，…，Δi φ.k (t))；
Calculate the division Δi φ.max (t) the sum Δi of the abrupt amounts of the current sampling values of the other branches outside the corresponding branch φ.s (t)，Δi φ.s (t)＝i φ.Σ (t)-Δi φ.max (t)；
Based on i φ.s (t) calculating second data comprises:
f 2 (t)＝(i a.s (t)-i b.s (t)) 2 +(i b.s (t)-i c.s (t)) 2 +(i c.s (t)-i a.s (t)) 2 ，
wherein Δi φ.k (t) is a current sampling value of the kth branch of phi phase at the moment t, and phi is A, B, C; i.e φ.Σ (t) is the sum of the current sample values of all branches of phi phase; f (f) 2 (t) is second data.
The bus protection system 1300 based on current sampling values according to the embodiment of the present invention corresponds to the bus protection method 100 based on current sampling values according to another embodiment of the present invention, and will not be described herein.
The invention has been described with reference to a few embodiments. However, as is well known to those skilled in the art, other embodiments than the above disclosed invention are equally possible within the scope of the invention, as defined by the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise therein. All references to "a/an/the [ means, component, etc. ]" are to be interpreted openly as referring to at least one instance of said means, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical aspects of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.
Claims (12)
1. A bus protection method based on current sampling values, the method comprising:
when the starting element meets a preset starting criterion and is started, current grouping is carried out on the basis of current abrupt change value sampling values of each side of the electric element at each sampling moment, and a first current abrupt change value and a second current abrupt change value corresponding to each sampling moment are determined;
Performing polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time;
performing point-by-point integration based on the first current abrupt change conversion value and the second current abrupt change conversion value corresponding to each sampling moment to obtain a first integral value and a second integral value;
and determining the fault type according to a preset bus protection criterion based on the first integral value and the second integral value, so as to perform bus protection based on the determined fault type.
2. The method of claim 1, wherein the determining the first current mutation amount and the second current mutation amount corresponding to each sampling time based on the current mutation amount sampling values of each sampling time on each side of the electrical element comprises:
for any sampling time, selecting the current abrupt change sampling value with the largest amplitude in the current abrupt change sampling values of all sides of the electric element at the any sampling time as the first current abrupt change delta i corresponding to the any sampling time m (t)＝max(|Δi 1 (t)|,|Δi 2 (t)|,…,|Δi h (t) |); determining a second current abrupt change delta i corresponding to any sampling moment according to the difference value between the sum of the current abrupt change sampling values of each side of the electric element at any sampling moment and the first current abrupt change n (t)＝Δi Σ (t)-Δi m (t)；
Wherein, |Δi h (t) is the amplitude of the current abrupt change sampling value at the sampling time t at the h side; Δi Σ And (t) is the sum of current mutation sampling values of each side of the electric element at the sampling time t.
3. The method of claim 1, wherein performing polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time includes:
for any sampling time, if the first current abrupt change delta i corresponding to any sampling time t m If the polarity of (t) is negative, determining Δi M (t)＝-Δi m (t)，Δi N (t)＝-Δi n (t); otherwise, determining Δi M (t)＝Δi m (t),Δi N (t)＝Δi n (t); wherein Δi n (t) is the samplingA second current abrupt change amount corresponding to the sample time t; Δi M (t) and Δi N (t) the first current abrupt change value and the second current abrupt change value, respectively.
4. The method of claim 1, wherein determining the fault type according to a preset bus protection criterion based on the first integrated value and the second integrated value comprises:
if the first current abrupt change conversion value and the second current abrupt change conversion value meet a preset bus protection criterion, determining that the fault type is a fault in a bus area; otherwise, determining the fault type as the fault outside the bus area;
The bus protection criterion is preset, and the bus protection criterion comprises:
wherein ΣΔi M (t) and ΣΔi N (t) a first current-abrupt change-over value and a second current-abrupt change-over value, respectively; i e Is the rated current of the bus bar protection device.
5. The method according to claim 1, wherein the method further comprises:
when the starting element meets the first preset promoter criterion or the second preset promoter criterion, determining that the starting element meets the preset starting criterion;
wherein the first preset promoter criterion comprises:
Δf 1 (t)＝f 1 (t)-f 1 (t-T/4)>f 1.set ，
the second preset promoter criterion comprises:
Δf 2 (t)＝f 2 (t)-f 2 (t-T/4)>f 2.set ，
wherein Δf 1 (t) is a first variation; Δf 2 (t) is a second variation; f (f) 1 (t) is first data at time t; f (f) 2 (t) is second data at time t; f (f) 1 (T-T/4) is f before quarter cycle 1 (t)；f 2 (T-T/4) is f before quarter cycle 2 (t)；f 1.set A first preset threshold value; f (f) 2.set Is a second predetermined threshold.
6. The method of claim 5, wherein the method further comprises:
calculating abrupt change delta i of each branch current sampling value of bus based on each branch current sampling value of bus φ.k (t) comprising:
Δi φ.k (t)＝i φ.k (t)-i φ.k (t-T s )，
calculating differential current i of each phase based on mutation amount of current sampling value of each branch φ.Σ (t) comprising:
calculating first data based on each phase difference stream, comprising:
f 1 (t)＝(i a.Σ (t)-i b.Σ (t)) 2 +(i b.Σ (t)-i c.Σ (t)) 2 +(i c.Σ (t)-i a.Σ (t) 2 ，
wherein i is φ.k (t) is the current sampling value of phi phase k branch at t time, phi is A, B, C, i φ.k (t-T s ) T-T being the kth branch of phi phase s Current sample value at moment, T s The time corresponding to the one-cycle wave; n is the number of branches; f (f) 1 (t) is first data; i.e a.Σ (t)、i b.Σ (t) and i c.Σ (t) is the differential flow of three phases A, B, C at time t respectively;
dividing the current of each branch of the bus into two groups, comparing the mutation amounts of the current sampling values of all branches, and determining the branch current delta i with the maximum mutation amount of the current sampling value φ.max (t)，Δi φ.max (t)＝max(Δi φ.1 (t),Δi φ.2 (t)，…，Δi φ.k (t))；
Calculate the division Δi φ.max (t) the sum Δi of the abrupt amounts of the current sampling values of the other branches outside the corresponding branch φ . s (t)，Δi φ.s (t)＝i φ.Σ (t)-Δi φ.max (t)；
Based on i φ.s (t) calculating second data comprises:
f 2 (t)＝(i a.s (t)-i b.s (t)) 2 +(i b.s (t)-i c.s (t)) 2 +(i c.s (t)-i a.s (t)) 2 ，
wherein Δi φ.k (t) is a current sampling value of the kth branch of phi phase at the moment t, and phi is A, B, C; i.e φ.Σ (t) is the sum of the current sample values of all branches of phi phase; f (f) 2 (t) is second data.
7. A bus bar protection system based on current sampled values, the system comprising:
the current abrupt change determining unit is used for grouping currents based on current abrupt change sampling values of each side of the electric element at each sampling moment when the starting element meets a preset starting criterion and determining a first current abrupt change and a second current abrupt change corresponding to each sampling moment;
The polarity conversion unit is used for respectively carrying out polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time so as to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time;
the integration unit is used for carrying out point-to-point integration based on the first current mutation amount conversion value and the second current mutation amount conversion value corresponding to each sampling time to obtain a first integration value and a second integration value;
and the bus protection unit is used for determining the fault type according to a preset bus protection criterion based on the first integral value and the second integral value so as to conduct bus protection based on the determined fault type.
8. The system according to claim 7, wherein the current abrupt amount determining unit performs current grouping based on current abrupt amount sampling values of each side of the electric element at each sampling time, and determines the first current abrupt amount and the second current abrupt amount corresponding to each sampling time, comprising:
for any sampling time, selecting the current abrupt change sampling value with the largest amplitude in the current abrupt change sampling values of all sides of the electric element at the any sampling time as the first current abrupt change delta i corresponding to the any sampling time m (t)＝max(|Δi 1 (t)|,|Δi 2 (t)|,…,|Δi h (t) |); determining a second current abrupt change delta i corresponding to any sampling moment according to the difference value between the sum of the current abrupt change sampling values of each side of the electric element at any sampling moment and the first current abrupt change n (t)＝Δi Σ (t)-Δi m (t)；
Wherein, |Δi h (t) is the amplitude of the current abrupt change sampling value at the sampling time t at the h side; Δi Σ And (t) is the sum of current mutation sampling values of each side of the electric element at the sampling time t.
9. The system of claim 7, wherein the polarity conversion unit performs polarity conversion on the first current abrupt change amount and the second current abrupt change amount corresponding to each sampling time to obtain a first current abrupt change amount conversion value and a second current abrupt change amount conversion value corresponding to each sampling time, respectively, and includes:
for any sampling time, if the first current abrupt change delta i corresponding to any sampling time t m If the polarity of (t) is negative, determining Δi M (t)＝-Δi m (t)，Δi N (t)＝-Δi n (t); otherwise, determining Δi M (t)＝Δi m (t),Δi N (t)＝Δi n (t); wherein Δi n (t) is a second current abrupt change amount corresponding to the sampling time t; Δi M (t) and Δi N (t) the first current abrupt change value and the second current abrupt change value, respectively.
10. The system of claim 7, wherein the bus bar protection unit determines the type of fault according to a preset bus bar protection criterion based on the first and second integrated values, comprising:
If the first current abrupt change conversion value and the second current abrupt change conversion value meet a preset bus protection criterion, determining that the fault type is a fault in a bus area; otherwise, determining the fault type as the fault outside the bus area;
the bus protection criterion is preset, and the bus protection criterion comprises:
wherein ΣΔi M (t) and ΣΔi N (t) a first current-abrupt change-over value and a second current-abrupt change-over value, respectively; i e Is the rated current of the bus bar protection device.
11. The system of claim 7, wherein the system further comprises:
the starting judgment unit is used for determining that the starting element meets the preset starting criterion when the starting element meets the first preset promoter criterion or the second preset promoter criterion;
wherein the first preset promoter criterion comprises:
Δf 1 (t)＝f 1 (t)-f 1 (t-T/4)>f 1.set ，
the second preset promoter criterion comprises:
Δf 2 (t)＝f 2 (t)-f 2 (t-T/4)>f 2.set ，
wherein Δf 1 (t) is a first variation; Δf 2 (t) is a second variation; f (f) 1 (t) is first data at time t; f (f) 2 (t) is second data at time t; f (f) 1 (T-T/4) is f before quarter cycle 1 (t)；f 2 (T-T/4) is one quarter cycle agof 2 (t)；f 1.set A first preset threshold value; f (f) 2.set Is a second predetermined threshold.
12. The system according to claim 11, wherein the start-up determination unit further comprises:
Calculating abrupt change delta i of each branch current sampling value of bus based on each branch current sampling value of bus φ . k (t) comprising:
Δi φ.k (t)＝i φ.k (t)-i φ.k (t-T s )，
calculating differential current i of each phase based on mutation amount of current sampling value of each branch φ.Σ (t) comprising:
calculating first data based on each phase difference stream, comprising:
f 1 (t)＝(i a.Σ (t)-i b.Σ (t)) 2 +(i b.Σ (t)-i c.Σ (t)) 2 +(i c.Σ (t)-i a.Σ (t) 2 ，
wherein i is φ.k (t) is the current sampling value of phi phase k branch at t time, phi is A, B, C, i φ.k (t-T s ) T-T being the kth branch of phi phase s Current sample value at moment, T s The time corresponding to the one-cycle wave; n is the number of branches; f (f) 1 (t) is first data; i.e a.Σ (t)、i b.Σ (t) and i c . Σ (t) is the differential flow of three phases A, B, C at time t respectively;
dividing the current of each branch of the bus into two groups, comparing the mutation amounts of the current sampling values of all branches, and determining the branch current delta i with the maximum mutation amount of the current sampling value φ.max (t)，Δi φ.max (t)＝max(Δi φ . 1 (t),Δi φ.2 (t)，…，Δi φ.k (t))；
Calculate the division Δi φ.max (t) outside the corresponding branchThe sum Δi of the abrupt amounts of the current sampling values of the remaining branches φ . s (t)，Δi φ.s (t)＝i φ.Σ (t)-Δi φ.max (t)；
Based on i φ.s (t) calculating second data comprises:
f 2 (t)＝(i a.s (t)-i b.s (t)) 2 +(i b.s (t)-i c.s (t)) 2 +(i c.s (t)-i a.s (t)) 2 ，
wherein Δi φ.k (t) is a current sampling value of the kth branch of phi phase at the moment t, and phi is A, B, C; i.e φ.Σ (t) is the sum of the current sample values of all branches of phi phase; f (f) 2 (t) is second data.
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