CN111308268B - Method and system for evaluating latent fault of power distribution network equipment - Google Patents
Method and system for evaluating latent fault of power distribution network equipment Download PDFInfo
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- CN111308268B CN111308268B CN202010081994.XA CN202010081994A CN111308268B CN 111308268 B CN111308268 B CN 111308268B CN 202010081994 A CN202010081994 A CN 202010081994A CN 111308268 B CN111308268 B CN 111308268B
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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
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1272—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- 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
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
Abstract
The application discloses an assessment method and system for latent faults of power distribution network equipment, and the assessment method and system are used for assessing latent faults of a power distribution network system.
Description
Technical Field
The application relates to the technical field of power distribution network state monitoring, in particular to a method and a system for evaluating latent faults of power distribution network equipment.
Background
The power distribution network is used as a supply and demand link for connecting a power transmission network and power consumers, belongs to the tail end of a power system, is directly oriented to the users, is an important public infrastructure for serving the people, and the reliability of power supply directly influences the development of national economy and the improvement of the living standard of people. With the rapid development of economy, the total power consumption and power utilization groups are rapidly increased, the complexity of a power distribution network is higher and higher, and the types and the number of power distribution network equipment are rapidly increased.
The 6kV-35kV medium-voltage power distribution network in China mostly adopts a low-current grounding mode, the structure is complex, and the line length of the power distribution network accounts for about 90% of that of each level of power grid. Compared with a high-voltage transmission line, the medium-voltage distribution network has a much higher fault probability, and nearly 75% of user power failure is caused by the medium-voltage distribution network. The power distribution network has the advantages of complex structure, more branch nodes, large line capacitance, variable and flexible operation modes, harsh operation environment and high fault occurrence frequency.
The distribution network comprises distribution substation, overhead line, cable, shaft tower, isolator, reactive compensation electric capacity and some accessory facilities etc. and distribution network equipment is various, huge in quantity, and the steady operation of distribution network equipment is the basis of distribution network safe operation, and the influence of equipment to the distribution network reliability level is not neglected. The state of the power distribution network equipment insulation is evaluated, latent faults existing in the equipment insulation are found in advance, the power distribution network equipment insulation is overhauled after being supplied, the power supply reliability of the power distribution network is improved, sudden accidents are reduced, and the pressure of operation and maintenance personnel is greatly reduced.
At present, in order to evaluate the state of the insulation of the power distribution network equipment and improve the power supply reliability, a large amount of research is carried out by related field personnel.
The patent with the application number of 201110382596.2 discloses a state maintenance control method of a power distribution network equipment state evaluation system, which judges whether the tested equipment has faults or not by judging the leakage current of an arrester and the temperature of a cable joint and formulates a maintenance plan. The method can be used for carrying out online detection on the tested equipment, but has low sensitivity for detecting leakage current and cable head temperature and even can not judge the defects of local insulation degradation, discharge and the like of the lightning arrester and the cable head.
The patent with application number 201811519232.2 discloses a movable platform for detecting a power distribution network relates to power distribution network detection equipment, and the equipment comprises a movable carrier, a data processing module, a detection module, an integrated wiring module and a man-machine interaction module, and solves the problems that the traditional factory is lack of mobility in cable experiments, low efficiency, long experiment period and the like. But the device can only detect the cable, and the non-contact detection sensitivity is low.
The patent with the application number of 201910694071.9 discloses a switch cabinet state evaluation method and a server, which are used for performing infrared temperature measurement, switch cabinet inspection, partial discharge detection and switch cabinet operation parameter monitoring on a switch cabinet, and evaluating the switch cabinet operation state according to a detection result. The method can only detect under the operation voltage, the operation voltage is relatively low, the detection sensitivity to insulation degradation and partial discharge is relatively low, and the state evaluation result is inaccurate.
At present, a common method for evaluating insulation latent faults of power distribution network equipment is a partial discharge monitoring method, and mainly comprises a method for measuring partial discharge by using an ultrahigh frequency method and an ultrasonic method, wherein the methods are limited by the measurement principle, only qualitative measurement can be carried out, quantitative measurement cannot be carried out, and the measurement accuracy of the two methods is difficult to guarantee under the charged condition. On the other hand, a general partial discharge test is performed at a voltage higher than the normal operation voltage of the device, and a latent fault (mainly, a partial discharge phenomenon due to a device insulation defect) is difficult to be found at the normal operation voltage.
In summary, the partial discharge monitoring method is widely applied to detecting the insulation latent fault of the power equipment, but the ground operation voltage of the power distribution network is low, so that the detection sensitivity of the latent fault is greatly reduced.
Disclosure of Invention
The application provides an assessment method and system for latent faults of power distribution network equipment, and aims to solve the problem that an existing assessment method for latent faults of power distribution network equipment is low in detection sensitivity.
In a first aspect, the present application provides a method for evaluating a latent fault of a power distribution network device, including:
s100, selecting one phase of A, B, C three-phase lines in the power distribution network system as an operation phase x, the other two phases as phases y and z to be tested, and the operation phase voltage corresponding to the operation phase x is UxThe phase voltage to be measured corresponding to the phase y and the phase z to be measured is Uy、UzWherein x, y, z is A, B or C;
s200, obtaining a starting setting value delta U0Reducing phase voltage of an operating phase to zero, simulating an operation state when a single-phase earth fault occurs in a power distribution network system, measuring voltage variation of a neutral point before and after the fault, and taking the voltage variation of the neutral point as a starting setting value delta U of an partial discharge detection module0；
S300, operating phase voltage UxPerforming multiple voltage reduction operations, and measuring voltage variation U of neutral point during each voltage reduction operationiI is the number of times of pressure reduction, i is 1, 2 … …;
s400, sequentially judging the variation U of the neutral point voltage in each voltage drop operationiWhether or not equal to the starting setting value delta U0When U is formediEqual to starting setting value delta U0Measuring the partial discharge of the power distribution network equipment on the phases y and z to be measured;
s500, judging whether the power distribution network equipment on the phases y and z to be tested has latent fault risks or not according to partial discharge of the power distribution network equipment on the phases y and z to be tested, and if the latent fault risks exist, calibrating the safety states of the power distribution network equipment on the phases y and z to be tested as the latent fault risks;
s600, changing the operation phase, and repeating the steps S200-S400 until A, B, C three phases are all used as one operation phase;
s700, whether the safety state of the power distribution network equipment on the three-phase line is calibrated as a latent fault risk at least twice is judged A, B, C, and if the safety state of the power distribution network equipment on the A, B or the C three-phase line is calibrated as a latent fault risk at least twice, it is judged that a latent fault exists in the power distribution network equipment on the A, B or the C three-phase line.
Optionally, S200, obtaining a start-up setting value Δ U0Specifically, the method comprises the following steps of,
s210, operating a control switch to enable an x-phase voltage corresponding to an operating phase x on the phase power supply generator to be connected to a neutral point;
s220, adjusting the output voltage of the phase power supply generator to make the phase voltage U operatexIs reduced to U'xCalculating the first neutral point voltage as U01＝Ux-U′x；
S230, secondarily regulating the phase power supply generator to operate the phase voltage UxReduced to UxCalculating the second neutral point voltage as U (0V)02＝Ux-U″x；
S240, according to the first neutral point voltage U01And the second neutral point voltage U02Calculating a starting setting value delta U0Wherein, Δ U0＝U01-U02＝U″x-U′x。
In a second aspect, the present application further provides a system for evaluating a latent fault of a distribution network device, for use in a distribution network system comprising A, B, C three-phase lines, comprising a phase supply generator for connection to a neutral point of the distribution network system, the phase supply generator comprising A, B, C three-phase supply lines, A, B, C three-phase supply lines generating respective U-phase distribution network system voltagesA、UBAnd UCVoltages with opposite phases and same amplitude;
a control switch is arranged on the connection between the phase power supply generator and the neutral point of the power distribution network system, and the control switch is used for controlling A, B, C three-phase power supply lines of the phase power supply generator to be correspondingly connected with A, B, C three-phase lines on the power distribution network system;
the evaluation system for the latent fault of the power distribution network equipment further comprises a fault evaluation device and a plurality of detection devices which are connected with the evaluation device, wherein each detection device comprises a three-phase coupling capacitor and a setting device and a partial discharge monitoring device which are connected with the three-phase coupling capacitor,
the three-phase coupling capacitor is used for coupling the partial discharge signal of the power distribution network equipment with the voltage value of the power distribution network system;
the setting device comprises:
the voltage acquisition module is used for acquiring the voltage value of the power distribution network system in real time;
a setting calculation module for calculating a start setting value delta U according to the neutral point voltage0；
A setting judgment module for judging the variation U of the neutral point voltageiWhether or not equal to the starting setting value delta U0；
The partial discharge starting module is used for sending a starting instruction to the partial discharge monitoring device;
the partial discharge monitoring device includes:
the partial discharge detection module is used for acquiring partial discharge signals of the power distribution network equipment;
the data transmission module is used for transmitting the partial discharge signal to the state evaluation device;
the system for evaluating the latent fault of the power distribution network equipment further comprises a plurality of groups of detection devices,
the fault evaluation device specifically includes:
the communication module is used for receiving the partial discharge signal;
the state calibration module is used for calibrating A, B or the safety state of the power distribution network equipment on the C three-phase line according to the partial discharge signal;
and the fault determination module is used for determining A, B whether the power distribution network equipment on the C three-phase line has a latent fault according to the safety state of the power distribution network equipment.
Optionally, one end of the three-phase coupling capacitor is installed on a high-voltage side of the power distribution network equipment, and the other end of the three-phase coupling capacitor is connected with the partial discharge monitoring device.
Optionally, one end of the partial discharge monitoring device is connected to the three-phase coupling capacitor, and the other end of the partial discharge monitoring device is grounded.
Optionally, the distribution of the plurality of detection devices is: and the detection devices are arranged on the lines of the power distribution network system at preset intervals.
The method comprises the steps that firstly, a certain phase line on A, B, C three-phase lines in the power distribution network system is used as an operation phase, the phase voltage of the operation phase is reduced to zero, the operation state of the power distribution network system when single-phase ground fault occurs is simulated, the voltage variation of a neutral point before and after the fault is measured, and the voltage variation of the neutral point is used as a starting setting value delta U of an partial discharge detection module0(ii) a Then, a plurality of operations for lowering the phase voltage of the operating phase are performed, and the neutral point voltage value U in the process is measurediWhen U is formediEqual to starting setting value delta U0Measuring partial discharge of power distribution network equipment on the other two phases of lines; and judging whether the power distribution network equipment on the two-phase line has a latent fault risk or not according to the partial discharge of the power distribution network equipment. And after A, B, C three phases are sequentially used as one-time operation phases, counting whether the safety state of the power distribution network equipment on the A, B, C three-phase line is calibrated as a latent fault risk at least twice, and if the power distribution network equipment on the A, B or C three-phase line is calibrated as a latent fault risk at least twice, judging that the power distribution network equipment on the A, B or C three-phase line has a latent fault.
In the process of evaluating the latent fault of the power distribution network equipment by adopting the method or the device, when the phase voltage of an operation phase is reduced, the phase voltages of the other two phases are correspondingly increased, the higher voltage acts on the power distribution network equipment, if the power distribution network equipment has a local amplification condition, the local discharge electric quantity is also correspondingly increased, and the larger local discharge quantity is convenient for acquisition and fault analysis.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a method for evaluating a latent fault of a power distribution network device according to the present application;
FIG. 2 is an equivalent circuit diagram of the system for evaluating the latent fault of the power distribution network equipment;
fig. 3 is a circuit diagram of the system for evaluating the latent fault of the power distribution network equipment.
The reference numerals in fig. 1-3 are respectively: the method comprises the following steps of 1-phase power supply generator, 2-control switch, 3-three-phase coupling capacitor, 4-partial discharge monitoring device, 5-fault evaluation device and 6-setting device.
Detailed Description
The application provides an evaluation method of a latent fault of power distribution network equipment, which is used for evaluating the latent fault of a power distribution network system. Fig. 1 is a flowchart of an evaluation method for a latent fault of a power distribution network device according to the present application, and as shown in fig. 1, the evaluation method for a latent fault of a power distribution network device includes:
s100, selecting one phase of A, B, C three-phase lines in the power distribution network system as an operation phase x, the other two phases as phases y and z to be tested, and the operation phase voltage corresponding to the operation phase x is UxThe phase voltage to be measured corresponding to the phase y and the phase z to be measured is Uy、UzWherein x, y, z is A, B or C;
s200, obtaining a starting setting value delta U0Reducing phase voltage of an operating phase to zero, simulating an operation state when a single-phase earth fault occurs in a power distribution network system, measuring voltage variation of a neutral point before and after the fault, and taking the voltage variation of the neutral point as a starting setting value delta U of an partial discharge detection module0；
In this example, the start-up setting value Δ U is obtained0Specifically, the method comprises the following steps of,
s210, operating a control switch to enable an x-phase voltage corresponding to an operating phase x on the phase power supply generator to be connected to a neutral point;
s220, adjusting the output voltage of the phase power supply generator to make the phase voltage U operatexIs reduced to U'xCalculating the first neutral point voltage as U01＝Ux-U′x；
S230, secondarily regulating the phase power supply generator to operate the phase voltage UxReduced to UxCalculating the second neutral point voltage as U (0V)02＝Ux-U″x；
S240, according to the first neutral point voltage U01And the second neutral point voltage U02Calculating a starting setting value delta U0Wherein, Δ U0＝U01-U02＝U″x-U′x。
S300, operating phase voltage UxPerforming multiple voltage reduction operations, and measuring voltage variation U of neutral point during each voltage reduction operationiI is the number of times of pressure reduction, i is 1, 2 … …. It should be noted that the operating conditions of the power distribution grid system at different voltages are simulated by a plurality of step-down operations. In addition, to prevent single-phase ground faults, the phase voltage U after the voltage drop operation processxShould be greater than zero.
S400, sequentially judging the variation U of the neutral point voltage in each voltage drop operationiWhether or not equal to the starting setting value delta U0When U is formediEqual to starting setting value delta U0And measuring the partial discharge of the power distribution network equipment on the phases y and z to be measured.
S500, judging whether the power distribution network equipment on the phases y and z to be tested has latent fault risks or not according to the partial discharge of the power distribution network equipment on the phases y and z to be tested, and if the latent fault risks exist, calibrating the safety states of the power distribution network equipment on the phases y and z to be tested as the latent fault risks.
It should be noted that, the determination of whether the distribution network equipment has a latent fault risk according to the partial discharge is a common technique for those skilled in the art, and a detailed implementation process will not be described herein.
And S600, changing the operation phase, and repeating the steps S200-S400 until A, B, C three phases are all used as one operation phase.
S700, whether the safety state of the power distribution network equipment on the three-phase line is calibrated as a latent fault risk at least twice is judged A, B, C, and if the safety state of the power distribution network equipment on the A, B or the C three-phase line is calibrated as a latent fault risk at least twice, it is judged that a latent fault exists in the power distribution network equipment on the A, B or the C three-phase line.
The application also provides an evaluation system of the latent fault of the power distribution network equipment, which is used for evaluating the latent fault of the power distribution network system, wherein the power distribution network system comprises A, B, C three-phase lines.
Fig. 2 is an equivalent circuit diagram of the system for evaluating a latent fault of a distribution network device, and fig. 3 is a circuit diagram of the system for evaluating a latent fault of a distribution network device, and as shown in fig. 2 and fig. 3, the system for evaluating a latent fault of a distribution network device comprises a phase power supply generator 1, the phase power supply generator 1 is used for being connected with a neutral point of the distribution network system, the phase power supply generator 1 comprises A, B, C three-phase power supply lines, and A, B, C three-phase power supply lines respectively generate voltages with opposite phases and same amplitudes as the voltages UA, UB, and UC of the distribution network system.
And a control switch is arranged on the connection between the phase power supply generator 1 and the neutral point of the power distribution network system, and the control switch is used for controlling A, B, C three-phase power supply lines of the phase power supply generator to be correspondingly connected with A, B, C three-phase lines on the power distribution network system.
The evaluation system for the latent fault of the power distribution network equipment further comprises a fault evaluation device and a plurality of detection devices which are connected with the evaluation device, wherein the distribution of the plurality of detection devices is as follows: and the detection devices are arranged on the lines of the power distribution network system at preset intervals.
The detection device comprises a three-phase coupling capacitor 3, and a setting device 6 and a partial discharge monitoring device 4 which are connected with the three-phase coupling capacitor 3. The three-phase coupling capacitor 3 is used for coupling a partial discharge signal of the power distribution network equipment with a voltage value of the power distribution network system. One end of the three-phase coupling capacitor 3 is installed on the high-voltage side of the power distribution network equipment, and the other end of the three-phase coupling capacitor is connected with the setting device 6 and the partial discharge monitoring device.
The setting device 6 comprises a voltage obtaining module, a setting calculating module, a setting judging module and a partial discharge starting module which are connected in sequence, wherein the voltage obtaining module is used for obtaining the voltage value of the power distribution network system in real time. The setting calculation module is used for calculating a starting setting value delta U according to the neutral point voltage0. The setting judgment module is used for judging the variable quantity U of the neutral point voltageiWhether or not equal to the starting setting value delta U0. The partial discharge starting module is used for sending a starting instruction to the partial discharge monitoring device, and during actual use, the variation U of neutral point voltageiEqual to starting setting value delta U0And then, sending a starting instruction to the partial discharge monitoring device 4, and acquiring a partial discharge signal of the power distribution network equipment by the partial discharge monitoring device 4 according to the starting instruction.
One end of the partial discharge monitoring device 4 is connected to the three-phase coupling capacitor 3, and the other end is grounded. The partial discharge monitoring device 4 comprises a partial discharge detection module and a data transmission module which are sequentially connected, wherein the partial discharge detection module is used for collecting partial discharge signals of the power distribution network equipment, and the data transmission module is used for transmitting the partial discharge signals to the state evaluation device.
The evaluation system for the latent fault of the power distribution network equipment further comprises a plurality of groups of detection devices, and the fault evaluation device 5 specifically comprises a communication module, a state calibration module and a fault determination module which are sequentially connected, wherein the communication module is used for receiving a partial discharge signal. And the state calibration module is used for calibrating A, B the safety state of the power distribution network equipment on the C three-phase line according to the partial discharge signal. And the fault determination module is used for determining A, B whether the power distribution network equipment on the C three-phase line has a latent fault according to the safety state of the power distribution network equipment.
The application provides an assessment method and system for latent faults of power distribution network equipment, which are used for assessing the latent faults of a power distribution network systemThe method comprises the steps of using a circuit as an operating phase, simulating the operation state of a power distribution network system when a single-phase earth fault occurs by reducing phase voltage of the operating phase to zero, measuring voltage variation of a neutral point before and after the fault, and using the voltage variation of the neutral point as a starting setting value delta U of an partial discharge detection module0(ii) a Then, a plurality of operations for reducing the phase voltage of the operation phase are carried out, the neutral point voltage value Ui in the process is measured, and when Ui is equal to the starting setting value delta U0Measuring partial discharge of power distribution network equipment on the other two phases of lines; and judging whether the power distribution network equipment on the two-phase line has a latent fault risk or not according to the partial discharge of the power distribution network equipment. And after A, B, C three phases are sequentially used as one-time operation phases, counting whether the safety state of the power distribution network equipment on the A, B, C three-phase line is calibrated as a latent fault risk at least twice, and if the power distribution network equipment on the A, B or C three-phase line is calibrated as a latent fault risk at least twice, judging that the power distribution network equipment on the A, B or C three-phase line has a latent fault.
In the process of evaluating the latent fault of the power distribution network equipment by adopting the method or the device, when the phase voltage of an operation phase is reduced, the phase voltages of the other two phases are correspondingly increased, the higher voltage acts on the power distribution network equipment, if the power distribution network equipment has a local amplification condition, the local discharge electric quantity is also correspondingly increased, and the larger local discharge quantity is convenient for acquisition and fault analysis.
The above-described embodiments of the present application do not limit the scope of the present application.
Claims (6)
1. A method for evaluating latent faults of power distribution network equipment is characterized by comprising the following steps:
s001, connecting a phase power supply generator with a neutral point of a power distribution network system, wherein A, B, C three-phase power supply lines of the phase power supply generator respectively generate a voltage U with the power distribution network systemA、UBAnd UCOpposite phase and amplitudeVoltages of the same value;
s100, selecting one phase of A, B, C three-phase lines in the power distribution network system as an operation phase x, the other two phases as phases y and z to be tested, and the operation phase voltage corresponding to the operation phase x is UxThe phase voltage to be measured corresponding to the phase y and the phase z to be measured is Uy、UzWherein x, y, z is A, B or C;
s200, obtaining a starting setting value delta U0Reducing phase voltage of an operating phase to zero, simulating an operation state when a single-phase earth fault occurs in a power distribution network system, measuring voltage variation of a neutral point before and after the fault, and taking the voltage variation of the neutral point as a starting setting value delta U of an partial discharge detection module0；
S300, operating phase voltage UxPerforming multiple voltage reduction operations, and measuring voltage variation U of neutral point during each voltage reduction operationiI is the number of times of pressure reduction, i is 1, 2 … …;
s400, sequentially judging the variation U of the neutral point voltage in each voltage drop operationiWhether or not equal to the starting setting value delta U0When U is formediEqual to starting setting value delta U0Measuring the partial discharge of the power distribution network equipment on the phases y and z to be measured;
s500, judging whether the insulation of the power distribution network equipment on the phases y and z to be tested has a latent fault risk or not according to the local discharge amount of the power distribution network equipment on the phases y and z to be tested, and if the latent fault risk exists, calibrating the safety state of the power distribution network equipment on the phases y and z to be tested as the latent fault risk exists;
s600, changing the operation phase, and repeating the steps S200-S400 until A, B, C three phases are all used as one operation phase;
s700, whether the safety state of the power distribution network equipment on the three-phase line is calibrated at least twice to be a latent fault risk or not is judged A, B, C, and if the safety state of the power distribution network equipment on the A, B or the C three-phase line is calibrated at least twice to be a latent fault risk, the situation that the power distribution network equipment on the A, B or the C three-phase line has a latent fault is judged.
2. The power distribution network of claim 1The method for evaluating the standby latent fault is characterized in that S200, a starting setting value delta U is obtained0Specifically, the method comprises the following steps of,
s210, operating a control switch to enable an x-phase voltage corresponding to an operating phase x on the phase power supply generator to be connected to a neutral point;
s220, adjusting the output voltage of the phase power supply generator to make the phase voltage U operatexIs reduced to U'xCalculating the first neutral point voltage as U01＝Ux-U′x；
S230, secondarily regulating the phase power supply generator to operate the phase voltage UxReduced to UxCalculating the second neutral point voltage as U (0V)02＝Ux-U″x；
S240, according to the first neutral point voltage U01And the second neutral point voltage U02Calculating a starting setting value delta U0Wherein, Δ U0＝U01-U02＝U″x-U′x。
3. An evaluation system for latent faults of power distribution network devices, for a power distribution network system comprising A, B, C three-phase lines, characterized by comprising a phase supply generator (1), the phase supply generator (1) being intended for connection to a neutral point of the power distribution network system, the phase supply generator (1) comprising A, B, C three-phase supply lines, A, B, C three-phase supply lines each generating a U voltage to the power distribution network systemA、UBAnd UCVoltages with opposite phases and same amplitude;
a control switch (2) is arranged on the connection between the phase power supply generator (1) and the neutral point of the power distribution network system, and the control switch (2) is used for controlling A, B, C three-phase power supply of the phase power supply generator to correspondingly control A, B, C three-phase line voltage on the power distribution network system;
the evaluation system for the latent fault of the power distribution network equipment further comprises a fault evaluation device and a plurality of detection devices which are connected with the evaluation device, wherein the detection devices comprise three-phase coupling capacitors (3), setting devices (6) and partial discharge monitoring devices (4) which are connected with the three-phase coupling capacitors (3),
the three-phase coupling capacitor (3) is used for coupling a partial discharge signal of the power distribution network equipment with a voltage value of the power distribution network system;
the setting device (6) includes:
the voltage acquisition module is used for acquiring the voltage value of the power distribution network system in real time;
a setting calculation module for calculating a starting setting value delta U according to the three-phase voltage of the system0；
A setting judgment module for judging the variation U of the neutral point voltageiWhether or not equal to the starting setting value delta U0；
The partial discharge starting module is used for sending a starting instruction to the partial discharge monitoring device;
the partial discharge monitoring device (4) comprises:
the partial discharge detection module is used for acquiring partial discharge signals of the power distribution network equipment;
the data transmission module is used for transmitting the partial discharge signal to the state evaluation device;
the system for evaluating the insulation latent fault of the power distribution network equipment further comprises a plurality of groups of detection devices,
the fault evaluation device (5) specifically comprises:
the communication module is used for receiving the partial discharge signal;
the state calibration module is used for calibrating A, B or the safety state of the power distribution network equipment on the C three-phase line according to the partial discharge signal;
and the fault determination module is used for determining A, B whether the power distribution network equipment on the C three-phase line has a latent fault according to the safety state of the power distribution network equipment.
4. The system for evaluating the latent fault of the power distribution network equipment according to claim 3, wherein one end of the three-phase coupling capacitor (3) is installed on the high-voltage side of the power distribution network equipment, and the other end of the three-phase coupling capacitor is connected with the partial discharge monitoring device.
5. The system for assessing the latent fault of the power distribution network equipment according to claim 3, characterized in that the partial discharge monitoring device (4) is connected to the three-phase coupling capacitor (3) at one end and to ground at the other end.
6. The system for assessing latent faults in power distribution network equipment according to claim 3, wherein the distribution of the plurality of detection devices is: and the detection devices are arranged on the lines of the power distribution network system at preset intervals.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010081994.XA CN111308268B (en) | 2020-02-06 | 2020-02-06 | Method and system for evaluating latent fault of power distribution network equipment |
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