CN111551824A - Phase voltage amplitude and phase angle change rate ground fault phase selection method and device considering three-phase asymmetry - Google Patents
Phase voltage amplitude and phase angle change rate ground fault phase selection method and device considering three-phase asymmetry Download PDFInfo
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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
- 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
Abstract
The invention discloses a phase voltage amplitude value and phase angle change rate ground fault phase selection method and device considering three-phase asymmetry. The method comprises the following steps: 1) and monitoring the zero sequence voltage in real time, and carrying out the next step when the zero sequence voltage in the system is more than 15% of phase voltage. 2) And recording the amplitude and the phase angle of each phase-to-ground voltage at the moment, and calculating the amplitude and the phase angle change rate of each phase-to-ground voltage by combining the amplitude and the phase angle of each phase-to-ground voltage before the fault. 3) And selecting a fault phase by using the phase voltage amplitude value and the phase angle change rate corresponding to the system operation mode in combination with a phase selection criterion. The phase selection method is suitable for different compensation states of the grounding transition resistor, the neutral point ungrounded and the arc suppression coil, fully considers the influence of three-phase asymmetry and the ground leakage resistor, and greatly improves the phase selection accuracy.
Description
Technical Field
The invention relates to the technical field of power distribution network ground fault phase selection; in particular to a phase voltage amplitude value and phase angle change rate earth fault phase selection method and a device considering three-phase asymmetry.
Background
The distribution network in China generally adopts an operation mode that a neutral point is not grounded and is grounded through an arc suppression coil. The line structure of the power distribution network is complex, the ground fault occurs frequently, and personal equipment and the operation safety of the power grid can be threatened if the fault is not cleared quickly. Therefore, domestic and foreign series arc suppression devices are widely applied to single-phase earth fault treatment, but the devices need to rely on accurate fault phase selection, and more serious accidents can be caused once the phase selection is wrong, so that accurate judgment of the earth fault phase is particularly important.
The traditional phase selection method is used for determining that the leading phase of the highest phase of three-phase voltage is a fault phase when the arc suppression coil is overcompensated, and the lagging phase of the highest phase of voltage is a fault phase when a neutral point is not grounded or the arc suppression coil is undercompensated. However, the method neglects line leakage resistance and does not consider the three-phase asymmetry condition, and in practice, the parameters of the power distribution network line are generally asymmetric, and when the line has a high-resistance ground fault, a phase selection error can be caused. The existing transmission network fault phase selection method mainly adopts a method of combining steady state quantity and mutation quantity. Wherein the mutation quantity phase selection mainly comprises the following steps: phase current difference abrupt change quantity phase selection, phase voltage difference abrupt change quantity phase selection and current voltage comprehensive abrupt change quantity phase selection. The steady-state quantity phase selection mainly comprises the following steps: current phase selection, voltage phase selection, impedance phase selection and sequence component phase selection. The related documents compare by using multiple parameters, so that the protection sensitivity is improved, but when the high-resistance grounding fault occurs, the influence of factors such as the leakage resistance to the ground of a line, the three-phase asymmetry and the like is not considered for the most part, so that the phase selection error still occurs at a higher probability. In actual power grid operation, the fault phase selection method is more susceptible to the influence of other interference factors, and fault characteristic information is more difficult to accurately extract, so that the fault phase selection precision is not high when the high resistance is high or the three-phase asymmetry of the system is high. The distribution network neutral point grounding mode, the system structure and the transmission network have great differences, most of the existing distribution network single-phase grounding fault phase selection methods are used for analyzing under the condition that three phases of the system are strictly symmetrical to ground parameters, and misjudgment can occur under certain conditions after the asymmetrical influence of the system is considered. Although some documents have studied the problem of fault phase identification under the condition of system asymmetry, the proposed methods all require measurement of parameters such as system asymmetry, which is not favorable for use in the power distribution network.
Disclosure of Invention
In order to solve the technical problem that fault phase identification under the condition of asymmetry of the existing system is inconvenient to realize, the invention provides a phase voltage amplitude and phase angle change rate ground fault phase selection method and device considering three-phase asymmetry.
In order to achieve the above object, the technical solution of the present invention is,
a phase voltage amplitude and phase angle change rate ground fault phase selection method considering three-phase asymmetry comprises the following steps:
recording amplitude values and phase angles of voltages relative to ground in a three-phase power distribution network in a normal operation state; simultaneously monitoring zero sequence voltage in real time, and executing a second step when the zero sequence voltage in the system is larger than the phase voltage and exceeds a preset threshold value;
recording the amplitude and phase angle of each phase-to-ground voltage at the moment, and calculating the amplitude and phase angle change rate of each phase-to-ground voltage by combining the amplitude and phase angle of each phase-to-ground voltage before failure;
step three, determining a fault phase according to the operation mode of the power distribution network system and the change rate of the phase voltage amplitude and the phase angle:
when the power distribution network system is in overcompensation operation through the arc suppression coil, if the amplitude change rate and the phase change rate of a certain phase voltage are both smaller than zero, the phase is a fault phase;
when the power distribution network system is in under-compensation operation through arc suppression coils or in ungrounded operation of a neutral point, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is greater than 0, the phase is a fault phase;
when the power distribution network system is in full compensation operation through arc suppression coils, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is 0, the phase is a fault phase.
In the phase voltage amplitude value and phase angle change rate ground fault phase selection method considering three-phase asymmetry, in the first step, when the preset threshold value is a proportionality coefficient of 15%, namely the zero sequence voltage exceeds 15% of the phase voltage, the second step is executed.
In the second step, the calculation formula of the change rate is as follows:
wherein, the three-phase voltage amplitude after the fault is U respectivelyAf、UBf、UCfAfter a fault, the three-phase voltage phases are respectively
Defining the change rate of three-phase voltage amplitude values before and after a fault as delta UXRate of change of phase with three-phase voltage
X represents one of A, B, C, and A, B, C represents one of the three phases respectively.
A phase voltage amplitude and phase angle change rate ground fault phase selection device considering three-phase asymmetry degree comprises:
the monitoring module is used for recording the amplitude and the phase angle of each phase-to-ground voltage in the three-phase power distribution network in a normal operation state; simultaneously, monitoring zero sequence voltage in real time, and when the zero sequence voltage in the system is larger than the phase voltage and exceeds a preset threshold value, sending the amplitude and the phase angle of each current phase-to-ground voltage to a change rate calculation module;
the change rate calculation module is used for receiving the amplitude and the phase angle of each phase-to-ground voltage sent by the monitoring module at present, and calculating the amplitude and the phase angle change rate of each phase-to-ground voltage by combining the amplitude and the phase angle of each phase-to-ground voltage before failure;
and the fault phase judgment module is used for determining a fault phase according to the operation mode of the power distribution network system and the change rate of the phase voltage amplitude and the phase angle:
when the power distribution network system is in overcompensation operation through the arc suppression coil, if the amplitude change rate and the phase change rate of a certain phase voltage are both smaller than zero, the phase is a fault phase;
when the power distribution network system is in under-compensation operation through arc suppression coils or in ungrounded operation of a neutral point, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is greater than 0, the phase is a fault phase;
when the power distribution network system is in full compensation operation through arc suppression coils, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is 0, the phase is a fault phase.
The phase voltage amplitude value and phase angle change rate ground fault phase selection device considering three-phase asymmetry is characterized in that a preset threshold value in the monitoring module is a proportionality coefficient of 15%, namely when zero-sequence voltage exceeds 15% of phase voltage, the amplitude value and the phase angle of each phase-to-ground voltage are sent to a change rate calculation module.
The phase voltage amplitude and the phase angle change rate earth fault phase selection device considering the three-phase asymmetry degree is characterized in that in the change rate calculation module, the calculation formula of the change rate is as follows:
wherein, the three-phase voltage amplitude after the fault is U respectivelyAf、UBf、UCfAfter a fault, the three-phase voltage phases are respectively
Defining the change rate of three-phase voltage amplitude values before and after a fault as delta UXRate of change of phase with three-phase voltage
X represents one of A, B, C, and A, B, C represents one of the three phases respectively.
An electronic device, comprising:
one or more processors;
a storage device for storing one or more programs,
when executed by the one or more processors, cause the one or more processors to implement a method as previously described.
A computer-readable medium, on which a computer program is stored which, when being executed by a processor, carries out the method as set forth above.
The invention has the technical effects that the invention covers a distribution network system which runs without grounding of a neutral point and grounding through an arc suppression coil, and has wide application range; the conditions of line leakage resistance and three-phase ground parameter asymmetry are fully considered, so that the phase selection result is more accurate and reliable when the high-resistance ground fault occurs; in addition, only three-phase outlet voltage and neutral point voltage need to be measured in the phase selection process, the existing measuring equipment can provide required data, corresponding phase selection equipment does not need to be added, the fault phase selection cost is low, and the engineering economy is high.
The invention will be further explained and explained with reference to the drawings.
Drawings
FIG. 1 is a schematic diagram of a basic principle of phase selection of a single-phase earth fault of a power distribution network;
FIG. 2 is a Thevenin equivalent circuit diagram at a point of failure of an asymmetric system;
FIG. 3 is a diagram of a zero potential trace for a symmetric system;
FIG. 4 is a diagram of an asymmetric system zero potential trace;
FIG. 5 is a zero sequence voltage trace diagram under the new coordinate system of the under-compensated system;
fig. 6 is a zero sequence voltage trace diagram of a full compensation system.
Detailed Description
Considering the actual running conditions of the power distribution network, such as power grid asymmetry, line-to-ground leakage conductance, arc suppression coil damping resistance and the like, the topological structure of the ground fault of the power distribution network is shown in figure 1,
are respectively three-phase power supply electromotive force,
respectively, the voltages of the three-phase lines to the ground. CA、CB、CCIs the capacitance of the three-phase line to ground, gA、gB、gCIs a three-phase line leakage conductor, RNIs a parallel resistance of an arc-suppression coil, LNIs the inductance of the arc suppression coil,
is the distribution network neutral point voltage, RfAnd GfRespectively fault transition resistance and transition conductance.
Assuming that three phases of the resonant system (the switch K at the neutral point is closed) are not completely equal to the ground parameters, when the phase A fails, the voltage at the neutral point of the distribution network can be expressed as:
in the formula, C∑＝CA+CB+CCTotal capacitance to ground, g∑＝gA+gB+gCIs the total electrical conduction to ground.
Introducing a phasor operator and arranging to obtain:
where a is a unit phasor operator, a is 1 ∠ 120 DEG,
defining system asymmetry
Is composed of
The system detuning degree upsilon is:
the system damping rate d is:
by substituting equations (3) to (5) for equation (2), the neutral point voltage can be simplified as:
in the formula: df＝1/RfωC∑The system damping rate due to transient conductance after a fault.
For a resonant grounded system, let d in equation (6)fWhen the system normally operates, the asymmetric voltage is 0:
the system is simplified by Thevenin theorem from fault resistance by setting the fault phase of the system as A phase, wherein the open-circuit voltage is
The equivalent impedance is that the neutral point impedance is connected in parallel with the line-to-ground impedance, and the equivalent circuit of the system is shown in fig. 2.
From FIG. 2, the neutral point voltage at fault can be determined
Comprises the following steps:
substituting the formula (3) to the formula (5) into the formula (8) to obtain:
to be provided with
For reference phasors, the following coordinate values are the result of dividing the actual value by the EA. The three-phase symmetrical zero-sequence voltage trace of the resonant grounding overcompensation system obtained by the formula (9) is shown in figure 3, and the zero-sequence voltage trace is located
Above and at the same time
A segment of arc of chord, wherein the center of the arc is located in the fourth quadrant
Radius of
The zero sequence voltage trace of the three-phase asymmetric resonant grounding overcompensation system can be obtained by the same equation (9) as shown in FIG. 4, wherein
Which represents the relative ground voltage of a during normal operation of the asymmetric system. The zero sequence voltage track of the asymmetric system is located
Above and at the same time
Is a segment of a chord of a circle, such as
For reference phasor, the center of the arc is
Radius of
For a resonant grounded system such as that shown in FIG. 1, the neutral point voltage is assumed to be at during normal system operation
The three-phase voltage amplitude is respectively
The phases of three-phase voltages are respectively
The neutral point voltage is
Three phases voltages are respectively
The phases of three-phase voltages are respectively
Defining the rate of change delta U of three-phase voltage amplitude values before and after a faultXRate of change of phase angle with three-phase voltage
Respectively as follows:
as shown in fig. 4. The zero sequence voltage track under the new coordinate system is in the first quadrant
Is a segment of a chord, similar to a symmetric system. It can be seen from the zero sequence voltage trace that: when a phase A in the resonant grounding overcompensation system has a single-phase grounding fault, the amplitude of a phase A relative ground voltage is reduced after the fault occurs, and the phase A relative ground voltage is lagged compared with the phase A relative ground voltage before the fault occurs; the amplitude of the B phase-to-ground voltage increases after the occurrence of a fault, and the phase of the B phase-to-ground voltage may be advanced or retarded compared to that before the faultThen; the magnitude of the C phase voltage relative to ground may be reduced or increased compared to before the fault, and the phase of the C phase voltage relative to ground is advanced compared to before the fault.
To be provided with
For reference phasors, the following coordinate values are the result of dividing the actual value by the EA. The zero sequence voltage track in the new coordinate system of the resonance grounding under-compensation system or the neutral point ungrounded system is shown in fig. 5, and can be seen from the zero sequence voltage track: when a phase A in a neutral point ungrounded system has a single-phase grounding fault after the resonant grounding under-compensation system, the amplitude of a phase A relative ground voltage is reduced after the fault occurs, and the phase A relative ground voltage is advanced compared with the phase A before the fault; the amplitude of the B phase to ground voltage may be reduced or increased compared to before the fault, and the phase of the B phase to ground voltage is lagged compared to before the fault; the magnitude of the C-phase voltage increases after the occurrence of the fault, and the phase of the C-phase voltage may be advanced or retarded compared to that before the fault.
To be provided with
For reference phasors, the following coordinate values are the result of dividing the actual value by the EA. The zero potential trace of the full compensation system is shown in FIG. 6, and the zero sequence voltage trace of the full compensation system is based on
As a starting point, the method comprises the following steps of,
is a straight line of the end point. As can be seen from the zero sequence voltage trace in fig. 6: when a phase A in the full compensation system has a single-phase earth fault, the amplitude of the phase A relative earth voltage is reduced after the fault occurs, and the phase A relative earth voltage is unchanged after the fault occurs; the amplitude of the voltage of the B phase to ground is increased after the fault occurs, and the phase of the voltage of the B phase to ground is lagged compared with that before the fault; the C phase to ground voltage amplitude increases after the fault occurs and the C phase to ground voltage phase leads before the fault.
By combining the above analysis, it is assumed that a single-phase earth fault occurs in the phase a of the system, and the amplitude and phase change law of the three-phase earth-voltage in different states of the neutral point to earth are shown in table 1.
TABLE 1 three-phase Voltage Change law under different grounding states
The data in table 1 are effectively analyzed, and the phase voltage amplitude and the phase angle change rate related to the system operation mode are combined with the phase selection criterion as follows:
1) phase voltage amplitude and phase angle change rate phase selection criterion for over-compensated operation of arc suppression coil
Criterion is as follows: in an over-compensation system of an arc suppression coil, before and after a ground fault, if the amplitude change rate and the phase change rate of a certain phase voltage are both smaller than zero, the phase is a fault phase;
2) phase voltage amplitude and phase angle change rate phase selection criterion of arc suppression coil under-compensation operation or neutral point ungrounded operation;
criterion is as follows: in an arc suppression coil under-compensation or neutral point ungrounded system, before and after a ground fault, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is more than 0, the phase is a fault phase;
3) phase voltage amplitude and phase angle change rate phase selection criterion of full compensation operation of arc suppression coil
Criterion is as follows: in the full compensation system of the arc suppression coil, before and after the ground fault, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is 0, the phase is a fault phase.
The method of the present embodiment according to the above analysis includes the steps of:
recording amplitude values and phase angles of voltages relative to ground in a three-phase power distribution network in a normal operation state; and simultaneously monitoring zero sequence voltage in real time, and executing the second step when the zero sequence voltage in the system is larger than the phase voltage and exceeds a preset threshold value.
And step two, recording the amplitude and the phase angle of each phase-to-ground voltage at the moment, and calculating the amplitude and the phase angle change rate of each phase-to-ground voltage by combining the amplitude and the phase angle of each phase-to-ground voltage before the fault.
Step three, determining a fault phase according to the operation mode of the power distribution network system and the change rate of the phase voltage amplitude and the phase angle:
when the power distribution network system is operated by overcompensation of the arc suppression coil, if the amplitude change rate and the phase change rate of a certain phase voltage are both smaller than zero, the phase is a fault phase.
When the power distribution network system is in under-compensation operation through arc suppression coils or in ungrounded operation of a neutral point, if the amplitude change rate of a certain phase voltage is smaller than 0 and the phase change rate is larger than 0, the phase is a fault phase.
When the power distribution network system is in full compensation operation through arc suppression coils, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is 0, the phase is a fault phase.
The device adopted by the embodiment comprises:
the monitoring module is used for recording the amplitude and the phase angle of each phase-to-ground voltage in the three-phase power distribution network in a normal operation state; and simultaneously, monitoring the zero sequence voltage in real time, and when the zero sequence voltage in the system is larger than the phase voltage and exceeds a preset threshold value, sending the amplitude and the phase angle of each current phase-to-ground voltage to a change rate calculation module.
And the change rate calculation module is used for receiving the amplitude and the phase angle of each phase-to-ground voltage currently sent by the monitoring module, and calculating the amplitude and the phase angle change rate of each phase-to-ground voltage by combining the amplitude and the phase angle of each phase-to-ground voltage before the fault.
And the fault phase judgment module is used for determining a fault phase according to the operation mode of the power distribution network system and the change rate of the phase voltage amplitude and the phase angle:
when the power distribution network system is operated by overcompensation of the arc suppression coil, if the amplitude change rate and the phase change rate of a certain phase voltage are both smaller than zero, the phase is a fault phase.
When the power distribution network system is in under-compensation operation through arc suppression coils or in ungrounded operation of a neutral point, if the amplitude change rate of a certain phase voltage is smaller than 0 and the phase change rate is larger than 0, the phase is a fault phase.
When the power distribution network system is in full compensation operation through arc suppression coils, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is 0, the phase is a fault phase.
The invention also provides an electronic device and a computer readable medium according to the embodiment of the invention.
Wherein electronic equipment includes:
one or more processors;
a storage device for storing one or more programs,
when executed by the one or more processors, cause the one or more processors to implement the aforementioned methods.
In specific use, a user can interact with a server which is also used as a terminal device through an electronic device which is used as the terminal device and based on a network, and functions of receiving or sending messages and the like are realized. The terminal device is generally a variety of electronic devices provided with a display device and used based on a human-computer interface, including but not limited to a smart phone, a tablet computer, a notebook computer, a desktop computer, and the like. Various specific application software can be installed on the terminal device according to needs, including but not limited to web browser software, instant messaging software, social platform software and the like.
The server is a network server for providing various services, such as a background server for providing corresponding computing services for received three-phase power distribution network operation data transmitted from the terminal device. The method and the device have the advantages that the three-phase power distribution network is monitored, fault phase judgment is carried out, and a final judgment result is returned to the terminal equipment.
The method for determining a fault phase provided in this embodiment is generally executed by a server, and in practical applications, a terminal device may also directly perform fault phase determination when necessary conditions are met.
Similarly, the computer-readable medium of the present invention stores thereon a computer program which, when executed by a processor, implements a fault phase determination method of an embodiment of the present invention.
The following example analysis is given:
by using the system parameters in table 2, an asymmetric power grid single-phase earth fault simulation model shown in fig. 1 is built in MATLAB/Simulink, phase selection simulation is performed in each operation mode, and relevant simulation data are shown in a relevant table below.
TABLE 2 simulation parameter settings for resonant grounding system of power distribution network
In the resonant grounding overcompensation system, the simulation phase A is grounded through transition resistors of 10 omega, 100 omega, 1000 omega, 5000 omega and 10000 omega respectively, the amplitude and phase angle information of three-phase voltage before and after a fault is recorded, the fault phase selection is carried out by utilizing the criterion provided by the invention, and the simulation result is shown in table 3. When the system normally operates, the three-phase voltage to ground is respectively as follows:
TABLE 3 simulation results of resonant grounding overcompensation system A phase grounding via different transition resistances
The resonant grounding under-compensation system is simulated when being grounded through different transition resistors, and the simulation result is shown in table 4. When the system normally operates, the three-phase voltage to ground is respectively as follows:
TABLE 4 simulation results of A-phase grounding via different transition resistances of resonant grounding under-compensation system
The simulation was performed when the resonant grounded full compensation system was grounded through different transition resistors, and the simulation results are shown in table 5. When the system normally operates, the three-phase voltage to ground is respectively as follows:
TABLE 5 simulation results of resonant grounding full compensation system A phase grounding via different transition resistors
From the simulation data in tables 3-5, it can be found that, when the phase a is grounded through different transition resistors in different resonant grounded compensation systems, the phase voltage amplitude and the phase angle change rate of the influence of the line on the ground leakage resistance can be correctly selected by considering the new phase selection method of the ground fault, and the phase voltage amplitude and the phase change condition of the fault are obviously distinguished from the phase not in fault, and the phase selection sensitivity is high.
Claims (8)
1. A phase voltage amplitude and phase angle change rate ground fault phase selection method considering three-phase asymmetry is characterized by comprising the following steps:
recording amplitude values and phase angles of voltages relative to ground in a three-phase power distribution network in a normal operation state; simultaneously monitoring zero sequence voltage in real time, and executing a second step when the zero sequence voltage in the system is larger than the phase voltage and exceeds a preset threshold value;
recording the amplitude and phase angle of each phase-to-ground voltage at the moment, and calculating the amplitude and phase angle change rate of each phase-to-ground voltage by combining the amplitude and phase angle of each phase-to-ground voltage before failure;
step three, determining a fault phase according to the operation mode of the power distribution network system and the change rate of the phase voltage amplitude and the phase angle:
when the power distribution network system is in overcompensation operation through the arc suppression coil, if the amplitude change rate and the phase change rate of a certain phase voltage are both smaller than zero, the phase is a fault phase;
when the power distribution network system is in under-compensation operation through arc suppression coils or in ungrounded operation of a neutral point, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is greater than 0, the phase is a fault phase;
when the power distribution network system is in full compensation operation through arc suppression coils, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is 0, the phase is a fault phase.
2. The phase voltage amplitude and phase angle change rate ground fault phase selection method considering the three-phase asymmetry according to claim 1, wherein in the first step, when the preset threshold value is a proportionality coefficient of 15%, that is, the zero sequence voltage exceeds 15% of the phase voltage, the second step is executed.
3. The phase voltage amplitude and phase angle change rate ground fault phase selection method considering three-phase asymmetry according to claim 1, wherein in said second step, the calculation formula of the change rate is:
wherein, the three-phase voltage amplitude after the fault is U respectivelyAf、UBf、UCfAfter a fault, the three-phase voltage phases are respectively
Defining the change rate of three-phase voltage amplitude values before and after a fault as delta UXRate of change of phase with three-phase voltage
X represents one of A, B, C, and A, B, C represents one of the three phases respectively.
4. A phase voltage amplitude and phase angle change rate ground fault phase selection device considering three-phase asymmetry degree is characterized by comprising:
the monitoring module is used for recording the amplitude and the phase angle of each phase-to-ground voltage in the three-phase power distribution network in a normal operation state; simultaneously, monitoring zero sequence voltage in real time, and when the zero sequence voltage in the system is larger than the phase voltage and exceeds a preset threshold value, sending the amplitude and the phase angle of each current phase-to-ground voltage to a change rate calculation module;
the change rate calculation module is used for receiving the amplitude and the phase angle of each phase-to-ground voltage sent by the monitoring module at present, and calculating the amplitude and the phase angle change rate of each phase-to-ground voltage by combining the amplitude and the phase angle of each phase-to-ground voltage before failure;
and the fault phase judgment module is used for determining a fault phase according to the operation mode of the power distribution network system and the change rate of the phase voltage amplitude and the phase angle:
when the power distribution network system is in overcompensation operation through the arc suppression coil, if the amplitude change rate and the phase change rate of a certain phase voltage are both smaller than zero, the phase is a fault phase;
when the power distribution network system is in under-compensation operation through arc suppression coils or in ungrounded operation of a neutral point, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is greater than 0, the phase is a fault phase;
when the power distribution network system is in full compensation operation through arc suppression coils, if the amplitude change rate of a certain phase voltage is less than 0 and the phase change rate is 0, the phase is a fault phase.
5. The phase voltage amplitude and phase angle change rate ground fault phase selection device considering three-phase asymmetry according to claim 4, wherein in the monitoring module, when the preset threshold is a proportionality coefficient of 15%, that is, the zero sequence voltage exceeds 15% of the phase voltage, the amplitude and phase angle of the current phase-to-ground voltage are sent to the change rate calculation module.
6. The phase voltage amplitude, phase angle change rate ground fault phase selection device of claim 4, wherein the change rate calculation module calculates the change rate according to the following formula:
wherein, the three-phase voltage amplitude after the fault is U respectivelyAf、UBf、UCfAfter a fault, the three-phase voltage phases are respectively
Defining the change rate of three-phase voltage amplitude values before and after a fault as delta UXRate of change of phase with three-phase voltage
X represents one of A, B, C, and A, B, C represents one of the three phases respectively.
7. An electronic device, comprising:
one or more processors;
a storage device for storing one or more programs,
when executed by the one or more processors, cause the one or more processors to implement the method of any one of claims 1-3.
8. A computer-readable medium, on which a computer program is stored, which, when being executed by a processor, carries out the method according to any one of claims 1-3.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111796212A (en) * | 2020-08-27 | 2020-10-20 | 广东电网有限责任公司电力调度控制中心 | Single-phase earth fault phase selection method, system and equipment for low-current earth system |
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| CN112462314A (en) * | 2020-11-25 | 2021-03-09 | 青岛鼎信通讯股份有限公司 | Three-phase voltage measurement asymmetric error elimination method for fault indicator |
| CN112462314B (en) * | 2020-11-25 | 2023-05-30 | 青岛鼎信通讯股份有限公司 | Three-phase voltage measurement asymmetry error elimination method for fault indicator |
| CN112684289A (en) * | 2020-12-15 | 2021-04-20 | 上海思源弘瑞自动化有限公司 | Non-full-phase operation state identification method and device, electrical protection equipment and medium |
| CN112684289B (en) * | 2020-12-15 | 2022-08-09 | 上海思源弘瑞自动化有限公司 | Non-full-phase operation state identification method and device, electrical protection equipment and medium |
| WO2022160778A1 (en) * | 2021-02-01 | 2022-08-04 | 易事特集团股份有限公司 | Three-phase power grid fault diagnosis method and apparatus, computer device and storage medium |
| CN113325268A (en) * | 2021-05-27 | 2021-08-31 | 长沙理工大学 | Asymmetric power grid single-phase high-resistance earth fault phase identification method considering line impedance |
| CN114325468A (en) * | 2021-12-01 | 2022-04-12 | 国网辽宁省电力有限公司锦州供电公司 | Method for conducting grounding phase selection and line selection by utilizing 66kV active intervention arc suppression device |
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