CN116577603A - Three-phase current abrupt change-based fault point residual current measuring and calculating method - Google Patents
Three-phase current abrupt change-based fault point residual current measuring and calculating method Download PDFInfo
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- CN116577603A CN116577603A CN202310495499.7A CN202310495499A CN116577603A CN 116577603 A CN116577603 A CN 116577603A CN 202310495499 A CN202310495499 A CN 202310495499A CN 116577603 A CN116577603 A CN 116577603A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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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
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
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- Y04S10/52—Outage or fault management, e.g. fault detection or location
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Abstract
The embodiment of the application provides a fault point residual current measuring and calculating method based on three-phase current abrupt change, relates to the technical field of power distribution automation, and aims to solve the technical problem that the existing power distribution network relay protection cannot calculate fault point residual current. And measuring the three-phase current abrupt quantity and the abrupt quantity difference by utilizing the three-phase current information of the detection points before and after the single-phase grounding fault of the resonance grounding system occurs, thereby realizing the residual current measurement and calculation of the fault point. The method can realize the calculation of the residual current of the fault point by measuring the three-phase current before and after the single-phase earth fault of the system, and has simple and clear principle and small calculated amount. The signal measurement can be completed by utilizing the existing current transformer of the system without separate measurement equipment. The influence of asymmetry of line parameters is overcome, and the accuracy is higher. The method is suitable for the random-type arc suppression coil and the preset-type arc suppression coil, and has strong applicability.
Description
Technical Field
The application relates to the technical field of power distribution automation, in particular to a fault point residual current measuring and calculating method based on three-phase current abrupt change.
Background
In the resonance grounding system, single-phase grounding faults are the most main fault types, and although the fault point residual current is smaller under the compensation action of the arc suppression coil, the damage to the stability of power equipment and the system is not great in a short time, and if the faults are not handled in time, more serious social accidents such as fire disaster, large-area power failure and the like are easily caused.
At present, main research work of relay protection of a power distribution network is concentrated on aspects of fault detection, line selection, positioning and the like, related technologies are relatively mature, and related equipment is relatively complete. However, since the fault excitation source is located at the fault point during the single-phase ground fault, the fault electric quantity of the detection point can only reflect the back admittance characteristic thereof, and the fault point residual current cannot be estimated, and therefore, a reasonable fault point residual current measuring and calculating technology is not yet available.
Disclosure of Invention
The embodiment of the application provides a fault point residual current measuring and calculating method based on three-phase current abrupt change, which is used for solving the technical problem that the existing power distribution network relay protection cannot calculate the fault point residual current.
The embodiment of the application provides a fault point residual current measuring and calculating method based on three-phase current abrupt change, which comprises the following steps:
step S1: and respectively recording the three-phase current when the system is normal and the system has single-phase earth fault.
Step S2: based on the following formula, the three-phase current abrupt change amount of the fault line outlet detection point P is calculated,
wherein , and />A, B and C-phase current abrupt changes of fault line outlet detection point P, respectively, +.> and />A, B and C-phase currents, respectively, of the normal operation detection point P, < >>Anda, B and C-phase currents at the point P after the single-phase earth fault.
Step S3: based on the following formula, the three-phase current abrupt change quantity of the fault line outlet detection point Q is calculated,
wherein , and />A, B and C-phase current abrupt changes of fault line outlet detection point P, respectively, +.> and />A, B and C-phase currents, respectively, of the normal operation detection point P, < >> and />A, B and C-phase currents at the point P after the single-phase earth fault.
Step S4: calculating three-phase current abrupt difference of the detection point P and the detection point Q based on the following formula,
wherein , and />The current abrupt differences of the phase A, the phase B and the phase C are respectively;
step S5: calculating a fault point residual current when the fault line detection point Q is located upstream of the fault point based on the following formula
Calculating fault point residual current when the fault line detection point Q is positioned upstream of the fault point based on the following formula
The fault point residual current measuring and calculating method based on the three-phase current abrupt change has the following beneficial effects:
(1) The method can realize the calculation of the residual current of the fault point by measuring the three-phase current before and after the single-phase earth fault of the system, and has simple and clear principle and small calculated amount.
(2) And signal measurement can be completed by utilizing the existing current transformer of the system without separate measurement equipment.
(3) The influence of asymmetry of line parameters is overcome, and the accuracy is higher.
(4) The device is suitable for an adjustable arc suppression coil and a preset arc suppression coil, and has strong applicability.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:
FIG. 1 is a flow chart of point of failure residual current measurement in an embodiment of the present application;
FIG. 2 is a diagram of a distribution automation circuit in an embodiment of the present application;
FIG. 3 is a typical 10kV resonant grounding system configuration employed in the simulation of an embodiment of the present application;
fig. 4 is a waveform diagram of three-phase current and fault point residual current of three detection points before and after single-phase earth fault of the obtained system through simulation verification in the embodiment of the application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to specific embodiments of the present application and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the resonance grounding system, single-phase grounding faults are the most main fault types, and although the fault point residual current is smaller under the compensation action of the arc suppression coil, the damage to the stability of power equipment and the system is not great in a short time, and if the faults are not handled in time, more serious social accidents such as fire disaster, large-area power failure and the like are easily caused.
At present, main research work of relay protection of a power distribution network is concentrated on aspects of fault detection, line selection, positioning and the like, related technologies are relatively mature, and related equipment is relatively complete. However, since the fault excitation source is located at the fault point during the single-phase ground fault, the fault electric quantity of the detection point can only reflect the back admittance characteristic thereof, and the fault point residual current cannot be estimated, and therefore, a reasonable fault point residual current measuring and calculating technology is not yet available.
The embodiment of the application provides a fault point residual current measuring and calculating method based on three-phase current abrupt change, and the technical scheme provided by the embodiment of the application is described in detail through the attached drawings.
Fig. 1 is a flowchart of a method for calculating a fault point residual current based on a three-phase current abrupt change according to an embodiment of the present application. As shown in fig. 1, the method mainly comprises the following steps:
step S1: and respectively recording the three-phase current when the system is normal and the system has single-phase earth fault.
Step S2: based on the following formula, the three-phase current abrupt change amount of the fault line outlet detection point P is calculated,
wherein , and />A, B and C-phase current abrupt changes of fault line outlet detection point P, respectively, +.> and />A, B and C-phase currents, respectively, of the normal operation detection point P, < >> and />A, B and C-phase currents at the point P after the single-phase earth fault.
Step S3: based on the following formula, the three-phase current abrupt change quantity of the fault line outlet detection point Q is calculated,
wherein , and />A, B and C-phase current abrupt changes of fault line outlet detection point P, respectively, +.> and />Respectively, detection in normal operationA, B and C-phase currents at point P, < >> and />A, B and C-phase currents at the point P after the single-phase earth fault.
Step S4: calculating three-phase current abrupt difference of the detection point P and the detection point Q based on the following formula,
wherein , and />The current abrupt differences of the phase A, the phase B and the phase C are respectively;
step S5: calculating a fault point residual current when the fault line detection point Q is located upstream of the fault point based on the following formula
Calculating fault point residual current when the fault line detection point Q is positioned upstream of the fault point based on the following formula
The feasibility of the application is verified by specific examples below.
At present, in a power distribution network, power distribution automation is widely applied, and in a normal state, the power distribution automation can monitor states of a line sectional switch and a tie switch and three-phase current and single-phase voltage conditions in real time, so that remote or on-site switching-on and switching-off operation of the line switch is realized; when faults occur, fault records are obtained, fault sections of the line can be automatically distinguished and isolated, and power supply is quickly recovered to a non-fault area. The distribution automation scheme mainly comprises two types of local control and remote control, wherein the remote control mode is characterized in that a distribution automation master station system is introduced, a computer system is used for completing works such as fault partition and positioning, the distribution automation scheme has stronger computing capacity, the switching action times are less, and the impact on the system is also small. With the increasing reliability of electronic communication devices, the cost of computers and communication devices is also lower and lower, and the advantages of remote control are more and more obvious.
As shown in fig. 2, after a single-phase earth fault occurs in the system, equipment such as a small-current earth fault line selection device, a distribution automation terminal and the like rapidly and accurately judges a fault line, a fault phase and a fault section, and on the other hand, the distribution automation platform collects three-phase voltages before and after the fault measured by the distribution automation terminal on the fault line, and according to the method disclosed by the application, the fault point residual current is calculated. And displaying the measuring and calculating result of the fault point residual current through man-machine interaction windows such as a display.
As shown in FIG. 3, in a typical 10kV resonant grounding system employed in the simulation, there are 5 wires, wherein the line L 1 -L 4 The three-phase symmetrical line comprises a cable line, an overhead line and a mixed line, and the line distribution parameters of different line types are shown in the table 1, R 0u 、L 0u and C0u The distributed resistance, inductance and capacitance parameters are respectively; line L 5 For a three-phase asymmetric line, the three relative ground parameters are shown in table 2. Simulation setting arc suppression coil inductance value L=0.2H, line L 5 The grounding resistor R of single-phase grounding fault is a fault line f =100deg.C, and respectively on line L 5 Upstream of the fault point and downstream of the fault pointA detection point is arranged at the trip and is marked as P, Q 1 and Q2 。
TABLE 1 line L 1 -L 4 Overhead line and cable line distribution parameters of (2)
TABLE 2 line L 5 Three-phase parameters of (2)
Before and after a single-phase earth fault occurs in the system, three-phase currents of each line are respectively measured by CT, and a line outlet detection point P and a fault point upstream detection point Q of the fault line are respectively measured 1 And a fault point downstream detection point Q 2 The measured three-phase current and fault point residual waveform is shown in fig. 3, where t=0 is the occurrence time of the fault. In practical cases, the fault point residual waveform cannot be directly measured, but can be obtained and used for verifying the correctness of the algorithm in simulation verification. Then, according to the flow shown in fig. 4, a method for measuring and calculating residual flow of a fault point is implemented. Detection point P, Q 1 and Q2 The three-phase currents and the abrupt amount and three-phase current abrupt amount difference are shown in table 3.
TABLE 3 line L 5 Three-phase parameters of (2)
Therefore, the detection points P and Q are utilized 1 Detection points P and Q 2 The calculated fault point residual current is respectively 11.02 DEG A and 10.55 DEG A, the simulated fault point residual current is 10.84 DEG A and 35.5 DEG A, and the difference between the calculated result and the measured result of the fault point residual current is smaller, thereby meeting the engineering requirements.
In summary, the method for measuring and calculating the fault point residual current based on the three-phase current abrupt change can measure the three-phase current before and after the single-phase grounding fault occurs in the system, and is simple and clear in principle and small in calculated amount. The signal measurement can be completed by utilizing the existing current transformer of the system without separate measurement equipment. The influence of asymmetry of line parameters is overcome, and the accuracy is higher. The method is suitable for the random-type arc suppression coil and the preset-type arc suppression coil, and has strong applicability.
The embodiments of the present application are described in a progressive manner, and the same and similar parts of the embodiments are all referred to each other, and each embodiment is mainly described in the differences from the other embodiments. In particular, for the device embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference is made to the description of the method embodiments in part.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.
The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and variations of the present application will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the application are to be included in the scope of the claims of the present application.
Claims (1)
1. The fault point residual current measuring and calculating method based on the three-phase current abrupt change is characterized by comprising the following steps of:
step S1: recording three-phase currents when the system is normal and single-phase earth fault occurs;
step S2: based on the following formula, the three-phase current abrupt change amount of the fault line outlet detection point P is calculated,
wherein , and />A, B and C-phase current abrupt changes of the fault line outlet detection point P, and />A, B and C-phase currents, respectively, of the normal operation detection point P, < >> and />A, B and C-phase currents of the detection point P after single-phase earth fault;
step S3: based on the following formula, the three-phase current abrupt change quantity of the fault line outlet detection point Q is calculated,
wherein , and />A, B and C-phase current abrupt changes of the fault line outlet detection point P, and />A, B and C-phase currents, respectively, of the normal operation detection point P, < >>Anda, B and C-phase currents of the detection point P after single-phase earth fault;
step S4: calculating three-phase current abrupt difference of the detection point P and the detection point Q based on the following formula,
wherein , and />The current abrupt differences of the phase A, the phase B and the phase C are respectively;
step S5: calculating a fault point residual current when the fault line detection point Q is located upstream of the fault point based on the following formula
Calculating fault point residual current when the fault line detection point Q is positioned upstream of the fault point based on the following formula
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| CN115792504A (en) * | 2023-01-31 | 2023-03-14 | 国网山西省电力公司电力科学研究院 | Phase current abrupt change based power distribution network single-phase earth fault positioning method and system |
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| WO2015118163A1 (en) * | 2014-02-10 | 2015-08-13 | Katholieke Universiteit Leuven | Direction detecting of a ground fault in a multiphase network |
| CN104793106A (en) * | 2015-04-28 | 2015-07-22 | 上海交通大学 | Distribution network line fault section positioning method based on current break rate |
| RU177833U1 (en) * | 2017-04-03 | 2018-03-14 | Александр Витальевич Вострухин | SIGNALING DEVICE FOR SINGLE-PHASE EARTH CLOSES |
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