A method and circuit for monitoring insulation faults in AC power supply systems for stations

Abstract

The present invention discloses a method and circuit for monitoring insulation faults in a station AC power supply system, wherein the method comprises: collecting three-phase voltage, line current, and three-phase voltage phase angle; calculating the line current vector sum based on the line current, and calculating the line apparent power based on the three-phase voltage and the three-phase voltage phase angle; determining whether the line current vector sum is 0; if not, outputting a line-to-ground insulation fault alarm based on the line current vector sum; if so, determining whether the line apparent power is greater than a preset line apparent power; if so, outputting an inter-line insulation fault alarm based on the line apparent power. Since an insulation fault is detected in real time in the station AC system, an alarm is output, so that when the station AC system loses power or a protection malfunction occurs, maintenance personnel can perform maintenance on the station AC system based on the alarm to reduce the impact of the fault.

Description

Technical Field

[0001] The present invention relates to the technical field of AC power supply system monitoring, and in particular to a method and a circuit for monitoring insulation faults of an AC power supply system for a station. Background Art

[0002] In today's society, with the continuous development of the economy, household electricity has become an integral part of people's lives. Typically, household electricity is supplied from substations, and station power supplies the primary and secondary equipment within the substation. Station power supplies include the forced oil circulation cooling system for large transformers, AC operating power, AC power for DC systems, AC power for heating, moisture control, lighting, and other equipment, AC power for UPS and SF6 gas monitoring devices, power for exhaust fans for normal and emergency use, and daily life such as lighting. This also presents the risk of insulation failure. Because existing technologies lack monitoring of station AC systems, this can indirectly lead to significant adverse consequences when the station AC system loses power or a protective device malfunctions. Summary of the Invention

[0003] In order to solve the above technical problems, the purpose of the present invention is to provide a method and circuit for monitoring insulation faults of an AC power supply system for a station.

[0004] The objectives of the present invention are achieved through the following technical solutions.

[0005] A first aspect of the present invention provides a method for monitoring insulation faults in an AC power supply system for a station, comprising:

[0006] Collect three-phase voltage, line current and three-phase voltage phase angle;

[0007] Calculating a line current vector sum according to the line current, and calculating a line apparent power according to the three-phase voltage and the three-phase voltage phase angle;

[0008] Determining whether the line current vector sum is 0;

[0009] If not, an alarm is issued based on the line current vector and the output line ground insulation fault;

[0010] If so, determining whether the line apparent power is greater than a preset line apparent power;

[0011] If so, an insulation fault alarm is issued between the apparent power output lines according to the line.

[0012] Optionally, the outputting an insulation fault alarm between lines according to the apparent power of the lines includes:

[0013] Recording the abnormal time when the apparent power of the line is greater than the preset apparent power of the line;

[0014] Determine whether the abnormal time is greater than a preset abnormal time;

[0015] If so, an inter-line insulation fault alarm is output according to the abnormal time.

[0016] Optionally, before the alarm of insulation fault between power output lines according to the line is generated, the method further includes:

[0017] Generates insulation fault records between lines.

[0018] Optionally, before issuing an alarm based on the line current vector and the output line ground insulation fault, the method further includes:

[0019] Generates line-to-ground fault records.

[0020] Optionally, after determining whether the line apparent power is equal to a preset line apparent power, the method further includes:

[0021] If so, re-collect the three-phase voltage, line current and three-phase voltage phase angle.

[0022] A second aspect of the present invention provides a circuit for monitoring insulation failure of an AC power supply system for a station, comprising:

[0023] A three-phase line, a neutral line, a first load circuit, a second load circuit, and a third load circuit; the three-phase line and the neutral line are respectively connected to the first load circuit; the three-phase line and the second load circuit are phase lines; and any one of the three-phase lines is connected to the third load circuit. The monitoring station uses a circuit for detecting insulation faults in the AC power system to apply the above method.

[0024] A third aspect of the present invention provides a device for monitoring insulation failure of an AC power supply system for a monitoring station, comprising:

[0025] An acquisition unit, used for acquiring three-phase voltage, line current and three-phase voltage phase angle;

[0026] a calculation unit, configured to calculate a line current vector sum based on the line current, and calculate a line apparent power based on the three-phase voltages and the three-phase voltage phase angles;

[0027] A first judging unit, configured to judge whether the line current vector sum is 0;

[0028] a first output unit, configured to output a line-to-ground insulation fault alarm according to the line current vector sum when the first judgment unit determines that the line vector sum is not 0;

[0029] a second judging unit, configured to judge whether the line apparent power is greater than a preset line apparent power when the first judging unit determines that the line vector sum is 0;

[0030] The second output unit is configured to output an inter-line insulation fault alarm according to the line apparent power when the second judgment unit determines that the line apparent power is greater than a preset line apparent power.

[0031] Optionally, the second output unit includes:

[0032] a recording module, configured to record an abnormal time when the line apparent power is greater than a preset line apparent power;

[0033] A judging module, configured to judge whether the abnormal time is greater than a preset abnormal time;

[0034] The output module is configured to output an inter-line insulation fault alarm according to the abnormal time when the judgment module determines that the abnormal time is greater than a preset abnormal time.

[0035] Optionally, the device further includes:

[0036] The first generating unit is used to generate an insulation fault record between lines.

[0037] Optionally, the device further includes:

[0038] The second generating unit is configured to generate a line-to-ground fault record.

[0039] Optionally, the acquisition unit is further configured to re-acquire the three-phase voltage, line current and three-phase voltage phase angle when the judgment module determines that the abnormal time is not greater than a preset abnormal time.

[0040] A fourth aspect of the present invention provides a device for monitoring insulation failure of an AC power supply system for a monitoring station, comprising:

[0041] A processor, a memory, an input / output device, and a bus; the processor is connected to the memory, the input / output device, and the bus.

[0042] The processor performs the following operations:

[0043] Collect three-phase voltage, line current and three-phase voltage phase angle;

[0044] Calculating a line current vector sum according to the line current, and calculating a line apparent power according to the three-phase voltage and the three-phase voltage phase angle;

[0045] Determining whether the line current vector sum is 0;

[0046] If not, an alarm is issued based on the line current vector and the output line ground insulation fault;

[0047] If so, determining whether the line apparent power is greater than a preset line apparent power;

[0048] If so, an insulation alarm is issued between the power output lines based on the apparent power of the lines.

[0049] An embodiment of the present application provides a computer-readable storage medium, on which a program is stored. When the program is executed on a computer, the aforementioned method is executed.

[0050] The present invention discloses a method for monitoring insulation faults in a station AC power system. The method monitors the station AC system using real-time data acquisition and monitoring. The method collects three-phase voltage, line current, and three-phase voltage phase angles; calculates the line current vector sum based on the line current, and calculates the line apparent power based on the three-phase voltage and the three-phase voltage phase angles; determines whether the line current vector sum is zero; if not, outputs a line-to-ground insulation fault alarm based on the line current vector sum; and if so, determines whether the line apparent power is equal to a preset line apparent power; if not, outputs an inter-line insulation fault alarm based on the line apparent power. Since an insulation fault is detected in the station AC system in real time, an alarm is output. This allows maintenance personnel to perform maintenance on the station AC system based on the alarm, minimizing the impact of a power outage or a misoperation of the protection system, thus minimizing the impact of the fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a flow chart of an embodiment of a method for monitoring insulation faults in an AC power supply system for a station according to an embodiment of the present application;

[0052] Figure 2 This is a flow chart of another embodiment of the method for monitoring insulation fault of an AC power supply system for a station according to an embodiment of the present application;

[0053] Figure 3 This is a circuit diagram of an insulation fault in an AC power supply system for a monitoring station in an embodiment of the present application;

[0054] Figure 4 This is a schematic structural diagram of an embodiment of a device for monitoring insulation failure of an AC power supply system for a monitoring station in an embodiment of the present application;

[0055] Figure 5 This is a structural diagram of another embodiment of the device for monitoring insulation failure of the AC power system for a monitoring station in the embodiment of the present application. DETAILED DESCRIPTION

[0056] An embodiment of the present application provides a method and circuit for monitoring insulation faults in a station AC power supply system. When an insulation fault is detected in the station AC system in real time, an alarm is output. When the station AC system loses power or a protection malfunction occurs, maintenance personnel can maintain the station AC system based on the alarm to reduce the impact.

[0057] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0058] See also Figure 1 and Figure 3 In one embodiment of the present application, a method for monitoring insulation faults in an AC power system for a monitoring station includes:

[0059] 101. Collect three-phase voltage, line current and three-phase voltage phase angle;

[0060] In this embodiment, the station AC power supply system uses the output of a three-phase transformer as the power supply. Figure 3 As shown in the figure. Its main power cables consist of phases A, B, and C, and the neutral line (neutral line), while the load circuits include a three-phase four-wire load circuit, a three-phase three-wire load circuit, and a single-phase load circuit, namely the first load circuit, the second load circuit, and the third load circuit, respectively. When the station AC power supply system is operating, current will flow through the phases A, B, C, and the neutral line (neutral line). At this time, the station AC power system insulation fault monitoring device is used to collect the line voltages of phases A, B, and C, the line currents passing through phases A, B, C, and the neutral line (neutral line), and the phase angles of phases A, B, and C.

[0061] 102. Calculate the line current vector sum based on the line current, and calculate the line apparent power based on the three-phase voltage and the three-phase voltage phase angle;

[0062] After collecting the three-phase voltage, line current and three-phase voltage phase angle, first calculate the line current vector sum based on the line current. For details: Figure 3 ,calculate Figure 3 The first line vector sum in the first load circuit is: a +I b +I c +I n ;calculate Figure 3 The second line vector sum in the second load circuit is: a +I b +I c ;calculate Figure 3 The third line vector sum in the third load circuit is: I 相 +I nThen the line apparent power is calculated based on the three-phase voltage and the three-phase voltage phase angle. The first line apparent power of the first load circuit is calculated as: the sum of the A phase line apparent power, the B phase line apparent power and the C phase line apparent power. The specific calculation formula is: U a *I a +U b *I b +U c *I c ; Calculate the apparent power of the second line of the second load circuit as: The third line apparent power of the third load circuit is calculated as: U*I, where U is the phase line voltage connected to the third load circuit; and I is the line current flowing through the third load circuit.

[0063] 103. Determine whether the line current vector sum is 0; if not, execute step 104; if so, execute step 105;

[0064] After obtaining the line current vector sum, if a grounding insulation fault occurs in the line, the substation uses the neutral line for grounding, and the substation ground network is a good ground grid with extremely low insulation resistance. After a grounding fault occurs, the current balance is broken, forming a leakage current. At this time, I a +I b +I c +I n ≠0 or I a +I b +I c ≠0 or I 相 +I n ≠0; therefore, the system first determines whether the line current vector sum is 0; in this embodiment, the system determines whether the line current vector sum is 0. When the current vector sum is 0, it indicates that the system determines that there is an output line-to-ground insulation fault in the output line; when the current vector sum is not 0, it indicates that the system determines that there is no output line-to-ground insulation fault in the output line.

[0065] 104. Alarm based on line current vector and output line ground insulation fault;

[0066] When the system determines that there is an output line insulation fault in the output line, the system generates an output line insulation fault alarm according to the cause of the insulation fault, so that the staff can deal with the system and the fault in a timely manner according to the output line insulation fault alarm to avoid causing greater losses.

[0067] 105. Determine whether the line apparent power is greater than the preset line apparent power; if so, execute step 106;

[0068] When the system determines that there is no output line insulation fault to ground, it further determines whether there is an insulation fault in the phase-to-ground circuit or the phase-to-zero circuit. When an insulation fault occurs in the phase-to-phase circuit or the phase-to-zero circuit, while the current balance of the power supply line remains intact, the load current will increase. The AC load power is constant, but some loads experience a sudden change in current during startup under special conditions. The difference between the characteristics of phase-to-phase and phase-to-zero circuit insulation faults is that the power increases under normal conditions, because the system needs to determine whether the line apparent power is greater than the preset line apparent power. When the line apparent power is not greater than the preset line apparent power, the system determines that there is no insulation fault in the phase-to-phase or phase-to-zero circuit. When the line apparent power is greater than the preset line apparent power, the system determines that there is an insulation fault in the phase-to-phase or phase-to-zero circuit.

[0069] 106. Output insulation fault alarm between lines based on apparent power of the line.

[0070] When the system determines that there is an insulation fault in the phase-to-phase circuit or phase-to-zero circuit in the output line, in order to enable the staff to realize the problem in time, the system will output an inter-line insulation fault alarm based on the apparent power of the line.

[0071] The system collects three-phase voltages, line currents, and three-phase voltage phase angles; calculates the line current vector sum based on the line current, and calculates the line apparent power based on the three-phase voltages and the three-phase voltage phase angles; determines whether the line current vector sum is 0; if not, outputs a line-to-ground insulation fault alarm based on the line current vector sum; if so, determines whether the line apparent power is equal to the preset line apparent power; if not, outputs an inter-line insulation fault alarm based on the line apparent power. Since an insulation fault is detected in real time in the station AC system, an alarm is output. This allows maintenance personnel to perform maintenance on the station AC system based on the alarm, minimizing the impact of a power outage or a misoperation of the protection system.

[0072] See also Figure 2 and Figure 3 Another embodiment of the method for monitoring insulation fault of an AC power system for a monitoring station in the embodiment of the present application includes:

[0073] 201. Collect three-phase voltage, line current and three-phase voltage phase angle;

[0074] 202. Calculate the line current vector sum based on the line current, and calculate the line apparent power based on the three-phase voltage and the three-phase voltage phase angle;

[0075] 203. Determine whether the line current vector sum is 0; if not, execute step 204; if so, execute step 206;

[0076] Steps 201 to 203 in this embodiment are similar to steps 101 to 103 in the aforementioned embodiment and are not described again here.

[0077] 204. Generate line-to-ground fault record;

[0078] After the system determines that there is an output line-to-ground insulation fault in the output line, the system automatically generates a line-to-ground fault record and saves the line-to-ground fault record to the local database. When the staff needs to query or use the fault data, they can directly retrieve it from the local database, thereby improving the speed of obtaining fault data.

[0079] 205. Alarm based on line current vector and output line ground insulation fault;

[0080] 206. Determine whether the line apparent power is greater than the preset line apparent power; if so, execute step 207; if not, execute step 201;

[0081] Steps 205 to 206 in this embodiment are similar to steps 104 to 105 in the aforementioned embodiment and are not described again here.

[0082] 207. Record the abnormal time when the line apparent power is greater than the preset line apparent power;

[0083] When the line apparent power exceeds the preset line apparent power, the system uses a timer to record the abnormal time during which the line apparent power exceeds the preset line apparent power and uploads the abnormal time to the system. This abnormal time provides the data basis for the system to determine whether the abnormal time exceeds the preset abnormal time in step 208.

[0084] In this embodiment, a timer may be used to measure the abnormal time, or a timer may be used to measure the abnormal time, which is not specifically limited here.

[0085] 208. Determine whether the abnormal time is greater than the preset abnormal time; if so, execute step 209; if not, execute step 201;

[0086] When the abnormal time recorded by the timer is uploaded to the system, the system receives the abnormal time. Due to the possibility of instantaneous current fluctuations, the line apparent power may be momentarily greater than the preset line apparent power. When the current stabilizes, the line apparent power is still equal to the preset line apparent power. If the system directly determines that there is an insulation fault in the phase-to-phase circuit or phase-to-zero circuit in the output line at this time, the judgment result will be less accurate. To improve the accuracy of the judgment result, the system determines whether the abnormal time is greater than the preset abnormal time. If the abnormal time is not greater than the preset abnormal time, the system determines that there is no insulation fault in the phase-to-phase circuit or phase-to-zero circuit in the output line. If the abnormal time is greater than the preset abnormal time, the system determines that there is an insulation fault in the phase-to-phase circuit or phase-to-zero circuit in the output line.

[0087] 209. Generate inter-line insulation fault records;

[0088] After determining that there is an insulation fault in the phase-to-phase circuit or phase-zero circuit in the output line, the system will automatically generate a line insulation fault record and save the fault record to the insulation fault table in the local database. When the system needs to call the fault data, it can be directly extracted from the insulation fault table in the database.

[0089] In this embodiment, the line insulation fault record may be saved in a local database or uploaded to the cloud, and the details are not limited here.

[0090] In this embodiment, step 209 is an optional step.

[0091] 210. Output line insulation fault alarm according to abnormal time;

[0092] After the system determines that there is an inter-line insulation fault in the output line based on the abnormal time, it generates one or more alarms for the inter-line insulation fault, prompting relevant staff to have an inter-line insulation fault in the output circuit, thereby improving the efficiency of repairing the relevant faulty lines.

[0093] See also Figure 4 In one embodiment of the present application, a device for detecting insulation failure of an AC power system for a monitoring station includes:

[0094] The acquisition unit 401 is used to acquire three-phase voltage, line current and three-phase voltage phase angle;

[0095] a calculation unit 402 for calculating a line current vector sum based on the line current, and calculating a line apparent power based on the three-phase voltages and the three-phase voltage phase angles;

[0096] A first judging unit 403 is configured to judge whether the line current vector sum is 0;

[0097] A first output unit 404 is configured to output a line-to-ground insulation fault alarm according to the line current vector sum when the first judgment unit 403 determines that the line vector sum is not 0;

[0098] A second judging unit 405 is configured to judge whether the line apparent power is greater than a preset line apparent power when the first judging unit 403 determines that the line vector sum is 0;

[0099] The second output unit 406 is configured to output an inter-line insulation fault alarm according to the line apparent power when the second judgment unit 405 determines that the line apparent power is greater than the preset line apparent power.

[0100] In this embodiment, the second output unit 406 may include a recording module 4061 , a judgment module 4062 , and an output module 4063 .

[0101] Recording module 4061, used to record the abnormal time when the line apparent power is greater than the preset line apparent power;

[0102] The judging module 4062 is used to judge whether the abnormal time is greater than the preset abnormal time;

[0103] The output module 4063 is configured to output an inter-line insulation fault alarm according to the abnormal time when the judgment module 4062 determines that the abnormal time is greater than the preset abnormal time.

[0104] In this embodiment, the device may further include a first generating unit 407 and a second generating unit 408 .

[0105] The first generating unit 407 is configured to generate a line insulation fault record.

[0106] The second generating unit 408 is configured to generate a line-to-ground fault record.

[0107] The collecting unit 401 is further configured to recollect the three-phase voltage, the line current and the three-phase voltage phase angle when the judging module 4062 determines that the abnormal time is not greater than the preset abnormal time.

[0108] In this embodiment, when the station AC power supply system is running, the collection unit 401 collects the three-phase voltage, line current and three-phase voltage phase angle, and sends the three-phase voltage, line current and three-phase voltage phase angle to the calculation unit 402. The calculation unit 402 calculates the line current vector sum according to the line current, and calculates the line apparent power according to the three-phase voltage and the three-phase voltage phase angle; sends the line current vector sum to the first judgment unit 403, and sends the line apparent power to the second judgment unit 405; the first judgment unit 403 judges whether the line current vector sum is 0; when the first judgment unit 403 determines that the line current vector sum is not 0, the first generation unit 407 generates an inter-line insulation fault record and the first output unit 404 A line-to-ground insulation fault alarm is output based on the line current vector sum; when the first judgment unit 403 determines that the line vector sum is 0, it determines whether the line apparent power is greater than the preset line apparent power; when the second judgment unit 405 determines that the line apparent power is greater than the preset line apparent power, the recording module 4061 records the abnormal time when the line apparent power is greater than the preset line apparent power, and then sends the abnormal time to the judgment module 4062, and the judgment module 4062 determines whether the abnormal time is greater than the preset abnormal time; when the judgment module 4062 determines that the abnormal time is greater than the preset abnormal time, the second generation unit 408 generates a line-to-ground fault record and the output module 4063 outputs a line-to-ground insulation fault alarm based on the abnormal time.

[0109] The following is a detailed description of the device for monitoring the insulation failure of the AC power system of the present application. Figure 5 Another embodiment of the device for detecting insulation failure of an AC power system for a monitoring station in the embodiment of the present application includes:

[0110] Processor 501, memory 502, input and output unit 503, bus 504;

[0111] The processor 501 is connected to the memory 502, the input and output unit 503 and the bus 504;

[0112] The processor 501 performs the following operations:

[0113] Collect three-phase voltage, line current and three-phase voltage phase angle;

[0114] Calculate the line current vector sum based on the line current, and calculate the line apparent power based on the three-phase voltage and the three-phase voltage phase angle;

[0115] Determine whether the line current vector sum is 0;

[0116] If not, an alarm is issued based on the line current vector and the output line-to-ground insulation fault;

[0117] If so, determine whether the line apparent power is equal to the preset line apparent power;

[0118] If not, an insulation alarm will be issued based on the apparent power output of the line.

[0119] In this embodiment, the function of the processor 501 is the same as that of the aforementioned Figures 1 to 2 The steps in the illustrated embodiment will not be repeated here.

[0120] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0121] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0122] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0123] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0124] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, read-only memory), random access memory (RAM, random access memory), disk or optical disk, and other media that can store program code.

Claims

1. A method for monitoring insulation faults in an AC power supply system for a monitoring station, characterized in that: include: Collect three-phase voltage, line current and three-phase voltage phase angle; Calculating a line current vector sum according to the line current, and calculating a line apparent power according to the three-phase voltage and the three-phase voltage phase angle; Determining whether the line current vector sum is 0; If not, an alarm is issued based on the line current vector and the output line ground insulation fault; If so, determining whether the line apparent power is greater than a preset line apparent power; If so, an insulation fault alarm is issued between the apparent power output lines according to the line; The outputting of an insulation fault alarm between lines according to the apparent power of the lines includes: Recording the abnormal time when the apparent power of the line is greater than the preset apparent power of the line; Determine whether the abnormal time is greater than a preset abnormal time; If so, outputting an inter-line insulation fault alarm according to the abnormal time; After determining whether the line apparent power is equal to the preset line apparent power, the method further includes: if so, re-collecting the three-phase voltage, line current and three-phase voltage phase angle.

2. The method according to claim 1, characterized in that Before the insulation fault alarm between the power output lines is generated according to the line, the method further includes: Generates insulation fault records between lines.

3. The method according to any one of claims 1 to 2, characterized in that Before issuing an alarm based on the line current vector and the output line ground insulation fault, the method further includes: Generates line-to-ground fault records.

4. A circuit for monitoring insulation failure of AC power supply system for a monitoring station, characterized in that: include: Three-phase line, neutral line, first load circuit, second load circuit, third load circuit; the three-phase line and the neutral line are respectively connected to the first load circuit; the three-phase line and the second load circuit phase line; any phase line of the three-phase line is connected to the third load circuit, and the circuit for detecting insulation failure of the AC power supply system used in the monitoring station is applied to the method described in claim 1.

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