CN111239599A - On-line monitoring device and method for opening and closing time of circuit breaker - Google Patents
On-line monitoring device and method for opening and closing time of circuit breaker Download PDFInfo
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Abstract
The invention provides a device and a method for monitoring the opening and closing time of a circuit breaker on line. The device comprises a three-phase current sensor, a three-phase voltage sensor, an analog quantity acquisition unit, a state quantity acquisition unit, a signal processing and storage unit, a central processing unit, a display unit, an operation unit and a communication unit; the three-phase current sensor and the three-phase voltage sensor are respectively connected with the analog quantity acquisition unit, the analog quantity acquisition unit is connected with the signal processing and storage unit, the signal processing and storage unit is connected with the central processing unit, and the state quantity acquisition unit, the display unit, the operation unit and the communication unit are connected with the central processing unit. The method can carry out on-line monitoring through the monitoring device. The on-line monitoring device and the method can eliminate the influence of interference such as inrush current, power transmission, sudden change of large load, instantaneous single-phase earth fault, other breaker switching-on and switching-off and the like, are not influenced by low voltage, overvoltage and load size, and have accurate and reliable monitoring time.
Description
Technical Field
The invention belongs to the technical field of power equipment testing, and relates to a device and a method for online monitoring the opening and closing time of a circuit breaker.
Background
As the operating voltage class of the power system is continuously improved, the capacity and the number of the high-voltage circuit breakers are continuously increased, and therefore, it is very important to judge the operation reliability of the high-voltage circuit breakers. The switching-on and switching-off operation of the high-voltage circuit breaker is completed by controlling all parts to sequentially move by an operating mechanism, and whether the circuit can be successfully switched on or switched off or not is determined. Besides the key function of the operating mechanism, the opening and closing time of the circuit breaker is also an important index for considering the characteristics of the circuit breaker, and the shorter the opening and closing time is, the smaller the impact on the power transmission and distribution line and the power equipment is. Therefore, the performance index of the opening and closing time of the circuit breaker is required to be generally within tens of milliseconds. At present, the measurement of the opening and closing time of the circuit breaker is generally completed under an off-line condition, namely, rated voltage is applied to the circuit breaker, the opening and closing time of the circuit breaker is indirectly measured by using a displacement sensor, the measured opening and closing time is measured under the condition of no load current, the error is large, and the reliability is low. Compared with a circuit breaker actually put into operation on a circuit, the larger the circuit load is, the longer the arc discharge generated during switching on and off, and the longer the switching on and off time is. Therefore, due to the fact that the opening and closing time of the circuit breaker under different load current conditions has a large difference due to the manufacturing process of the circuit breaker and the like, at present, there is no method for monitoring the actual opening and closing time of the circuit breaker on line, and the actual performance of the circuit breaker is not considered. If the opening and closing time of the circuit breaker can not be monitored in real time during actual operation, the following problems can be caused:
1. when a fault occurs, the circuit breakers at all levels from the fault point to the power supply point feel the fault. When the opening time of the upper-stage circuit breaker is less than that of the lower-stage circuit breaker, the upper-stage circuit breaker in a fault line can be tripped in priority over the lower-stage circuit breaker, and therefore override tripping is caused, and fault section isolation fails.
2. In actual operation, whether the time performance of opening and closing of the circuit breaker exceeds the standard or not is irrespectively considered, so that the service life of the circuit breaker cannot be evaluated.
The invention provides a technical solution, which aims to realize a device and a method for monitoring the on-line time of a circuit by acquiring and recording high-speed data of a high-frequency voltage signal, a high-frequency current signal and a switching-on and switching-off state signal of the circuit which are acquired on line in real time, and then calculating, analyzing and processing a voltage/current waveform and the state signal to obtain the switching-on and switching-off time.
Disclosure of Invention
In view of the deficiencies in the prior art, it is an object of the present invention to address one or more of the problems in the prior art as set forth above. For example, one of the objectives of the present invention is to provide an online monitoring device and method for the opening and closing time of a circuit breaker.
In order to achieve the above object, an aspect of the present invention provides an on-line monitoring device for opening and closing time of a circuit breaker, wherein the device comprises a three-phase current sensor, a three-phase voltage sensor, an analog quantity acquisition unit, a state quantity acquisition unit, a signal processing and storage unit, a central processing unit, a display unit, an operation unit, a communication unit, etc.; the three-phase current sensor and the three-phase voltage sensor are respectively connected with the analog quantity acquisition unit; the analog quantity acquisition unit is connected with the signal processing and storage unit; the signal processing and storing unit is connected with the central processing unit; the state quantity acquisition unit, the display unit, the operation unit and the communication unit are respectively connected with the central processing unit.
Furthermore, the analog quantity acquisition unit comprises an overvoltage protection module, a signal conditioning module and a plurality of high-speed analog-to-digital conversion A/Ds formed by a plurality of high-speed analog-to-digital conversion A/Ds; the three-phase voltage sensor and the three-phase current sensor transmit voltage/current signals detected on line to a plurality of high-speed analog-to-digital conversion A/Ds through the overvoltage protection module and the signal conditioning module respectively; the high-speed analog-to-digital conversion A/D respectively converts the voltage/current analog signals into digital signals and transmits the digital signals to the signal processing and storing unit.
Further, the three-phase voltage sensor is an A/B/C three-phase high-frequency voltage sensor, the three-phase current sensor is an A/B/C three-phase high-frequency current sensor, and the plurality of high-speed analog-to-digital conversion A/Ds are 6 high-speed analog-to-digital conversion A/Ds.
Further, the overvoltage protection module receives voltage/current signals from a three-phase high-frequency voltage sensor and a three-phase high-frequency current sensor respectively, and comprises a voltage-stabilized power supply, a current-expanding triode, a voltage-stabilized diode, a light-emitting diode and a fuse; the regulated power supply consists of a three-terminal regulator and a current-expanding triode, and the regulating end potential of the regulated power supply is raised by the voltage drop of a voltage-stabilizing diode and a light-emitting diode in series connection; the overvoltage protection adopts a silicon controlled short circuit power supply mode to force the fuse to be rapidly fused so as to protect the safety of a later-stage circuit.
Further, the fusing time of the fuse is 1-3 microseconds; the voltage-stabilized power supply is 12V/5A; the voltage stabilizing range of the overvoltage protection module is 12V +/-2%.
Furthermore, the signal conditioning module is a ZCM2301D module, and the signal conditioning module can convert +/-3-5V voltage signals from the overvoltage protection module into +/-2-3 mA current signals.
Furthermore, the high-speed analog-to-digital conversion A/D adopts 1.8V single power supply for power supply, 8-channel, 14-bit and 50MSPS analog-to-digital converters are provided with built-in sampling and holding circuits and are packaged by 64-pin LFCSP which accords with the RoHS packaging standard, and the rated temperature range is-40 ℃ to +85 ℃.
Furthermore, the signal processing and storing unit carries out data preprocessing and pre-operation on the received signal, and the signal processing and storing unit internally comprises an 8-channel digital sampling interface; the unit performs data preprocessing and logic pre-operation on the received signals; the unit also comprises a programmable input/output unit, a programmable logic unit, clock management, an embedded block RAM, an embedded bottom layer functional unit, an embedded special hardware module and the like; the high-precision clock of the synchronous clock code in the unit can generate a time signal with the precision reaching the mu s level, and the time signal is sent to the FPGA for the FPGA to accurately calibrate the trigger time, so that the recorded and stored waveform has an accurate time mark; the time signal input is in a 1PPS mode, and the synchronous signal receiving circuit directly receives 1PPS pulses from a GPS synchronous clock; and the SRAM 1-4 in the FPGA is a static random access memory, and caches the acquired high-frequency voltage and current waveforms.
Further, the signal processing and storing unit sends the data signals after preprocessing and preprocessing operation to the central processing unit for further operation and processing through an internal CAN bus interface.
Furthermore, the central processing unit is an STM32f407VG type DSC chip and is connected with the state quantity acquisition unit, the display unit, the operation unit and the communication unit; the ARM chip is provided with a wireless communication interface and an Ethernet communication interface, can generate PWM waves, and can quickly process and output analog quantity, picture signals, control signals and alarm signals.
Furthermore, the state quantity acquisition unit is connected with the central processing unit through optical coupling isolation, can acquire on-column switch on-off state signals in real time and sends the state signals to the central processing unit; the optical coupling isolation adopts a photoelectric coupler; the central processing unit is connected with the remote combat-assisting system through a network card.
Further, the display unit comprises an indicator light and a liquid crystal display screen, and is respectively connected with the central processing unit through optical coupling isolation; the indicating lamp comprises a state indicating lamp, a power supply indicating lamp, a communication indicating lamp, a fault indicating lamp, an operation indicating lamp and a self-checking indicating lamp; the liquid crystal display is a human-computer interaction interface and can display the opening and closing time, the opening and closing state and the fault signal of the on-column switch in real time.
Furthermore, the operation unit is connected with the central processing unit through optical coupling isolation and comprises an upper button, a lower button, a left button, a right button, a cancel button and a confirm button.
Further, the communication unit comprises a remote communication network port and a USB debugging interface which are connected with the remote master station system; the remote communication network port is connected with the remote master station system, sends signals of the remote communication network port to the master station system and receives various instructions from the master station system; the USB debugging interface is connected with an external computer, and monitors program updating or constant value parameter setting.
The invention provides a method for monitoring the opening and closing time of a circuit breaker on line, which comprises the following steps:
comparing the detected line voltage value with a preset voltage value and a preset duration threshold value to judge whether to record waves or not;
step two, simultaneously comparing the detected and collected high-frequency transient current signal value with a preset current integral threshold value and a preset duration value to judge whether wave recording is carried out or not;
step three, transmitting the wave recording waveform data to a central processing unit, and simultaneously acquiring and processing opening and closing state signals by the central processing unit;
and step four, the central processing unit sends signals to the master station system/receives various instructions from the master station system.
Further, in the step one, when the line voltage value is detected>8kV and duration>Starting wave recording when the time is 10 s; when the detected line voltage>8kV and duration T1<At 10s, no recording is performed.
Further, the high frequency transient current signal in the second step>AsetAnd for a time duration<3s, begin recording, locking and storing current>AsetThe voltage/current waveforms in the pre-and post-periods of the time point. When the duration is>At 3s, the recording is not performed, wherein AsetIs a preset threshold value.
Further, in the second step, the front time period and the rear time period are 1s and 2s, respectively.
Further, in the third step, the status signal is collected by the sensor and transmitted to the central processing unit at a high speed.
Further, the status signals collected in step three include:
when the collected state signal is unchanged, judging that the circuit has transient single-phase earth fault or inrush current or interference caused by other switching-on/off switches at a lower stage;
when the collected state signal is collected and changed from 0 to 1, switching on and switching off at the moment, and calculating the time of the high-frequency voltage waveform recorded at the switching on starting moment, wherein the time window from the voltage initial mutation moment to the voltage stabilization moment is the switching on and switching off time;
and when the acquired state signal changes from 1 to 0, switching on and switching off at the moment, and performing time calculation on a high-frequency current waveform recorded at the starting moment of switching off, wherein the time window from the initial sudden change moment of the current to the current stabilization moment is the switching on and switching off time.
Further, in the third step, time calculation is performed on the high-frequency voltage waveform recorded at the switching-on and switching-off starting time and/or the high-frequency current waveform recorded at the switching-off and switching-on starting time, and the following formula and conditions are followed:
when a certain collected primary current signal meets the condition that i is more than or equal to isetThen, the current sampling values of the voltage/current waveform data 1s before and 2s after the trigger time are integrated:
wherein i is the value of the collected current signal, isetFor the preset current threshold value, j is the sampling sequence number of the current at the initial moment of each integration period, i.e. the sampling point from the first current is i1The second current sampling point is i2J current sampling point is ijSampling until the Nth sampling point iNAt the end, N is the number of sampling points included in each integration period.
If the absolute value of the numerical integration is larger than or equal to the set value, the opening and closing operation of the circuit breaker can be carried out, namely, the following conditions are met:
|A|≥Aset
wherein A issetTo preset threshold value, when the amplitude of the given high-frequency current is greater than the set value, locking is started and the current greater than A is storedsetVoltage current waveform data of the first 1s and the second 2s of the time point, AsetFor a range of current thresholds reached in the event of a fault, AsetThe selection is between 10A and 6300A.
Further, the instructions in step three include an opening/closing instruction, and the opening/closing instruction is determined according to the following equation and conditions:
if the switching-off time is the switching-off time, the switching-off time is as follows:
Tf＝TIn-TI1
if the switching-on is carried out, the switching-on time is as follows:
Th＝TUn-TU1
wherein, TfFor calculated circuit breaker opening time, ThFor calculated closing time of the circuit breaker, TInThe current recording end time T during openingI1The starting time of current recording during openingUnFor the end time of voltage recording at closing time, TU1The starting time of voltage recording during closing.
Compared with the prior art, the invention has the beneficial effects that:
according to the on-line monitoring device and method for the opening and closing time of the circuit breaker, three-dimensional signals are monitored on line, high-speed processing is acquired in real time, the influences of interference such as inrush current, power transmission, sudden change of large load, instantaneous single-phase earth fault and other circuit breaker opening and closing are eliminated, meanwhile, the influences of low voltage, overvoltage and load size are avoided, and the monitoring time is accurate and reliable; by alarming, the generation of misoperation or override trip is avoided.
Drawings
The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic structural diagram of an on-line monitoring device for the opening and closing time of a circuit breaker according to the invention;
FIG. 2 is a schematic structural diagram of an on-line monitoring device for the opening and closing time of a circuit breaker according to the invention;
FIG. 3 is a logic and wave recording judgment flow chart of the on-line monitoring device for the opening and closing time of the circuit breaker of the invention;
FIG. 4 is a control chart of on-line monitoring of opening and closing time of the breaker according to the invention;
fig. 5 is a recording diagram of the opening and closing waveforms of the circuit breaker on-line monitoring of the opening and closing time, wherein the diagram (a) is a recording diagram of the opening waveforms, and the diagram (b) is a recording diagram of the closing waveforms.
Description of reference numerals:
the system comprises a 1-three-phase current sensor, a 2-three-phase voltage sensor, a 3-analog quantity acquisition unit, a 4-signal processing and storage unit, a 5-central processing unit, a 6-state quantity acquisition unit, a 7-display unit, an 8-operation unit and a 9-communication unit.
Detailed Description
Hereinafter, the on-line monitoring device and method for the opening and closing time of the circuit breaker according to the present invention will be described in detail with reference to the accompanying drawings and exemplary embodiments.
Example 1
As shown in fig. 1, the on-line real-time monitoring device for the switching-on and switching-off time of the pole-mounted switch of the high-voltage circuit breaker, provided by the invention, comprises a three-phase current sensor 1, a three-phase voltage sensor 2, an analog quantity acquisition unit 3, a signal processing and storage unit 4, a central processing unit 5, a state quantity acquisition unit 6, a display unit 7, an operation unit 8, a communication unit 9 and the like; the three-phase current sensor 1 and the three-phase voltage sensor 2 respectively transmit current and voltage signals detected on line to the analog quantity acquisition unit 3; the analog quantity acquisition unit 3 respectively converts the current analog signals into digital signals and transmits the digital signals to the signal processing and storage unit 4; the signal processing and storage unit 4 is used for preprocessing and pre-calculating input signal data and sending signals to the central processing unit 5; the central processing unit 5 further operates and processes the input signal data; the central processing unit 5 is respectively connected with the state quantity acquisition unit 6, the display unit 7, the operation unit 8 and the communication unit 9, and can rapidly process and output analog quantity, picture signals, control signals, alarm signals and the like. The central processing unit 5 is connected with a remote main station system through a network card.
As shown in fig. 3, the method for monitoring the opening and closing time of the pole top switch of the high-voltage circuit breaker on line in real time provided by the invention. The on-line real-time monitoring method of the invention can carry out on-line real-time monitoring based on the on-line real-time monitoring device, and comprises the following steps,
comparing the detected line voltage value with a preset voltage value and a preset duration threshold value to judge whether to record waves or not;
step two, simultaneously comparing the detected and collected high-frequency transient current signal value with a preset current integral threshold value and a preset duration value to judge whether wave recording is carried out or not;
step three, the wave recording waveform data is sent to a Central Processing Unit (CPU)5, and the CPU5 collects and processes switching-on and switching-off state signals at the same time;
and step four, a Central Processing Unit (CPU)5 sends signals to/receives various instructions from the master station system.
Example 2
As shown in fig. 1 and 2, the on-line real-time monitoring device for the switching-on and switching-off time of the pole-mounted switch of the high-voltage circuit breaker provided by the invention comprises a three-phase current sensor 1, a three-phase voltage sensor 2, an analog quantity acquisition unit 3, a signal processing and storage unit 4, a central processing unit 5, a state quantity acquisition unit 6, a display unit 7, an operation unit 8, a communication unit 9 and the like; the three-phase current sensor 1 and the three-phase voltage sensor 2 respectively transmit current and voltage signals detected on line to the analog quantity acquisition unit 3; the analog quantity acquisition unit 3 respectively converts the current analog signals into digital signals and transmits the digital signals to the signal processing and storage unit 4; the signal processing and storage unit 4 is used for preprocessing and pre-calculating input signal data and sending signals to the central processing unit 5; the central processing unit 5 further performs logical operation and processing on the input signal data; the central processing unit 5 is respectively connected with the state quantity acquisition unit 6, the display unit 7, the operation unit 8 and the communication unit 9, and can rapidly process and output analog quantity, picture signals, control signals, alarm signals and the like.
Further, as shown in fig. 2, the analog quantity acquisition unit 3 includes an overvoltage protection module, a signal conditioning module, and a high-speed analog-to-digital conversion a/D; the voltage sensor 1 and the current sensor 2 transmit online detected voltage/current signals to a plurality of high-speed analog-to-digital conversion A/Ds through an overvoltage protection module and a signal conditioning module respectively; the high-speed analog-to-digital conversion A/D respectively converts the voltage/current analog signals into digital signals and transmits the digital signals to the signal processing and storing unit 4.
Furthermore, the voltage sensor is an A/B/C three-phase high-frequency voltage sensor, the current sensor is an A/B/C three-phase high-frequency current sensor 2, and the plurality of high-speed analog-to-digital conversion A/Ds are 6 high-speed analog-to-digital conversion A/Ds.
Furthermore, the overvoltage protection module respectively receives voltage/current signals from a three-phase high-frequency voltage sensor and a three-phase high-frequency current sensor, and comprises a voltage-stabilized power supply, a current-expanding triode, a voltage-stabilized diode, a light-emitting diode, a fuse and the like; the regulated power supply consists of a three-terminal regulator and a current-expanding triode, and the regulating end potential of the regulated power supply is raised by the voltage drop of a voltage-stabilizing diode and a light-emitting diode in series connection; the overvoltage protection adopts a silicon controlled short circuit power supply mode to force the fuse to be rapidly fused so as to protect the safety of a later-stage circuit.
Furthermore, the fusing time of the fuse is 1-3 microseconds; the voltage-stabilized power supply is 12V/5A; the overvoltage protection module has the following voltage stabilization ranges: 12V, ± 1%.
Furthermore, the signal conditioning module adopts a ZCM2301D module to convert a +/-3-5V voltage signal from the overvoltage protection module into a +/-2-3 mA current signal.
Furthermore, the high-speed analog-to-digital conversion A/D module adopts a 1.8V single power supply to supply power, and is provided with an 8-channel, 14-bit and 50MSPS analog-to-digital converter (ADC) and an in-chip sampling and holding circuit; the package is realized by adopting 64-pin LFCSP (Long-lead chip Package) which meets the RoHS (RoHS) package standard, and the rated temperature range is-40 ℃ to +85 ℃.
Further, the signal processing and storage unit (FPGA)4 is mainly used for preprocessing and pre-operating collected signal data, an 8-channel digital sampling interface is arranged in the signal processing and storage unit, and the FPGA receives digital signals and performs data preprocessing and logic pre-operation. The FPGA is composed of a programmable input/output unit, a programmable logic unit, a clock management unit, an embedded block RAM, an embedded bottom layer functional unit and an embedded special hardware module 6, and integrates functions of the RAM, the clock management unit, the DSP and the like. The FPGA internal synchronous clock codes, and the time signals with the precision reaching the mu s level generated by the high-precision clock are sent to the FPGA for the FPGA to accurately calibrate the trigger time, so that the recorded and stored waveform has an accurate time scale. The time signal input is in a 1PPS mode, and the synchronous signal receiving circuit directly receives 1PPS pulses from a GPS synchronous clock. And the SRAM 1-4 in the FPGA is a static random access memory, and caches the acquired high-frequency voltage and current waveforms.
Furthermore, the signal processing and storage unit (FPGA)4 pre-operates and pre-processes signal data through an internal CAN bus interface, and then sends the signal data to the Central Processing Unit (CPU)5 for further logical operation and processing. The FPGA4 may also include static memory cells that store data. The FPGA4 is a programmable logic array.
Further, the Central Processing Unit (CPU)5 is a DSC chip of STM32f407VG type, and is connected to the state quantity acquisition unit 6, the display unit 7, the operation unit 8, and the communication unit 9. The ARM chip is provided with a wireless communication interface and an Ethernet communication interface, can generate PWM waves, and can quickly process and output analog quantity, picture signals, control signals, alarm signals and the like.
Further, the state quantity acquisition unit 6 is connected with a Central Processing Unit (CPU)5 through optical coupling isolation, acquires opening and closing state signals of a switch on a column of the circuit breaker in real time, and sends the state signals to the CPU 5. The optical coupling isolation adopts a photoelectric coupler; the CPU5 is connected to the remote master station system through a network card.
Furthermore, the display unit 7 comprises an indicator light and a liquid crystal display screen which are respectively connected with the Central Processing Unit (CPU)5 through optical coupling isolation; the indicating lamp comprises a state indicating lamp, a power supply indicating lamp, a communication indicating lamp, a fault indicating lamp, an operation indicating lamp, a self-checking indicating lamp and the like. The liquid crystal display is a human-computer interaction interface and displays the opening and closing time, the opening and closing state, the fault signal and the like of the switch on the column of the circuit breaker in real time.
Further, the operation unit 8 is connected to the CPU5 through optical coupling isolation, and includes operation keys such as "up, down, left, right, cancel, determine", and the like.
Further, the communication unit 9 includes a remote communication network port and a USB debug interface connected to the remote master station system; the remote communication network port is connected with the remote master station system, sends signals of the remote communication network port to the master station system, and receives various instructions from the master station system. The USB debugging interface is connected with an external computer, and is used for monitoring program updating or setting fixed value parameters and the like.
As shown in fig. 3, the method for on-line real-time monitoring of the opening and closing time of the pole-mounted switch of the high-voltage circuit breaker provided by the invention comprises the following steps,
comparing the detected line voltage value with a preset voltage value and a preset duration threshold value to judge whether to record waves or not;
step two, simultaneously comparing the detected and collected high-frequency transient current signal value with a preset current integral threshold value and a preset duration value to judge whether wave recording is carried out or not;
step three, the wave recording waveform data is sent to a Central Processing Unit (CPU)5, and the CPU5 collects and processes switching-on and switching-off state signals at the same time;
and step four, a Central Processing Unit (CPU)5 sends signals to/receives various instructions from the master station system.
Further, in the step one, when the line voltage value is detected>8kV and duration>Starting wave recording when the time is 10 s; when the detected line voltage>8kV and duration T1<At 10s, no recording is performed.
Further, the high frequency transient current signal in the second step>AsetAnd for a time period T2<3s, begin recording, locking and storing current>AsetThe front time period and the rear time period of the time point are poweredVoltage/current waveforms. When the duration T is>At 3s, no recording is performed.
Further, in the second step, the front time period and the rear time period are 1s and 2s, respectively.
Further, in the third step, the status signal is collected by a sensor and transmitted to a Central Processing Unit (CPU) at a high speed.
Further, the status signals collected in step three include:
when the collected state signal is unchanged, judging that the circuit has transient single-phase earth fault or inrush current or interference caused by other switching-on/off switches at a lower stage;
when the acquired state signal changes from 0 → 1, switching on and switching off the brake at the moment, and performing time calculation on the high-frequency voltage waveform recorded at the starting moment of switching on the brake; the time window from the voltage initial mutation moment to the voltage stabilization moment is the opening and closing time of the switch;
when the collected state signal changes from 1 → 0, the brake is switched on and off at the moment, and time calculation is carried out on the high-frequency current waveform recorded at the starting moment of the brake division; and the time window from the initial sudden change moment of the current to the current stabilization moment is the opening and closing opening time.
Furthermore, in the third step, time calculation is performed on the high-frequency voltage wave/high-frequency current wave recorded at the closing/opening starting time of the opening/closing switch, and the following formula and conditions are followed:
when a certain collected primary current signal meets the condition that i is more than or equal to isetThen (c) is performed. Integrating the current sampling values of the voltage/current waveform data 1s before and 2s after the trigger time:
in the above formula, i is the value of the collected current signal, isetIs a preset current threshold value. j is the sampling number of the current at the initial moment of each integration period, i.e. i is the sampling point from the first current1The second current sampling point is i2J current sampling point is ijSampling until the Nth sampling point iNFinishing; n is the number of sampling points included in each integration period (50M sampling frequency, N is the 100 th ten thousand sampling points).
If the absolute value of the numerical integration is larger than or equal to the set value, the opening and closing operation of the circuit breaker can be carried out, namely, the following conditions are met:
|A|≥Aset(2)
in the above formula, AsetFor presetting a threshold value, when the amplitude of the given high-frequency current is greater than a set value, the FPGA starts to lock and stores the current greater than AsetVoltage and current waveform data of the first 1s and the second 2s of the time point. A. thesetOne range reached for the current threshold in the event of a fault: 10A to 6300A, A may be provided in this intervalsetThe value of (c). When | A | ≧ AsetThe circuit breaker switching-on and switching-off state signals collected by the CPU can be used for judging whether the circuit breaker is switched on or switched off.
Further, as shown in fig. 4, the switching-off/switching-on command determination in step three follows the following equation and conditions:
if the switching-off time is the switching-off time, the switching-off time is as follows:
Tf＝TIn-TI1(3)
if the switching-on is carried out, the switching-on time is as follows:
Th＝TUn-TU1(4)
in the above formula, TfFor calculated circuit breaker opening time, ThCalculating the closing time of the breaker; t isInThe current recording end time T during openingI1The starting time of current recording during opening; t isUnFor the end time of voltage recording at closing time, TU1The starting time of voltage recording during closing.
The on-line monitoring opening and closing waveform recording chart of the opening and closing time of the circuit breaker is shown in fig. 5. Wherein, the graph (a) is a switching-off waveform recording graph, and the graph (b) is a switching-on waveform recording graph.
In conclusion, the on-line monitoring device and the method for the opening and closing time of the circuit breaker eliminate the influences of interference such as inrush current, power transmission, sudden large load, transient single-phase grounding fault and other circuit breaker opening and closing by on-line monitoring of three-dimensional signals and real-time acquisition and high-speed processing, are not influenced by low voltage, overvoltage and load size, and have accurate and reliable monitoring time; by alarming, the generation of misoperation or override trip is avoided.
Although the present invention has been described above in connection with exemplary embodiments, it will be apparent to those skilled in the art that various modifications and changes may be made to the exemplary embodiments of the present invention without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (22)
1. The on-line monitoring device for the opening and closing time of the circuit breaker is characterized by comprising a three-phase current sensor, a three-phase voltage sensor, an analog quantity acquisition unit, a state quantity acquisition unit, a signal processing and storage unit, a central processing unit, a display unit, an operation unit and a communication unit; the three-phase current sensor and the three-phase voltage sensor are respectively connected with the analog quantity acquisition unit; the analog quantity acquisition unit is connected with the signal processing and storage unit; the signal processing and storing unit is connected with the central processing unit; the state quantity acquisition unit, the display unit, the operation unit and the communication unit are respectively connected with the central processing unit.
2. The on-line monitoring device for the opening and closing time of the circuit breaker according to claim 1, wherein the analog quantity acquisition unit comprises an overvoltage protection module, a signal conditioning module and a plurality of high-speed analog-to-digital conversion A/Ds; the three-phase voltage sensor and the three-phase current sensor transmit voltage/current signals detected on line to a plurality of high-speed analog-to-digital conversion A/Ds through the overvoltage protection module and the signal conditioning module respectively; the high-speed analog-to-digital conversion A/Ds respectively convert the voltage/current analog signals into digital signals and transmit the digital signals to the signal processing and storage unit.
3. The on-line monitoring device for the opening and closing time of the circuit breaker according to claim 2, wherein the three-phase voltage sensor is an A/B/C three-phase high-frequency voltage sensor; the three-phase current sensor is an A/B/C three-phase high-frequency current sensor; the plurality of high-speed analog-to-digital conversion A/Ds are 6 high-speed analog-to-digital conversion A/Ds.
4. The on-line circuit breaker opening and closing time monitoring device according to claim 3, wherein the overvoltage protection module receives voltage/current signals from a three-phase high-frequency voltage sensor and a three-phase high-frequency current sensor respectively; the overvoltage protection module comprises a voltage-stabilized power supply, a current-expanding triode, a voltage-stabilizing diode, a light-emitting diode and a fuse; the regulated power supply is composed of a three-terminal regulator and a current-expanding triode, and the regulating end potential of the regulated power supply is raised by the voltage drop of the series connection of a voltage-stabilizing diode and a light-emitting diode; the overvoltage protection adopts a silicon controlled short circuit power supply mode to force the fuse to be rapidly fused so as to protect the safety of a later-stage circuit.
5. The on-line monitoring device for the opening and closing time of the circuit breaker according to claim 4, wherein the fusing time of the fuse is 1-3 microseconds; the voltage-stabilized power supply is 12V/5A; the voltage stabilizing range of the overvoltage protection module is 12V +/-2%.
6. The on-line monitoring device for the opening and closing time of the circuit breaker according to claim 2, wherein the signal conditioning module is a ZCM2301D module; the signal conditioning module can convert a +/-3-5V voltage signal from the overvoltage protection module into a +/-2-3 mA current signal.
7. The on-line monitoring device for the opening and closing time of the circuit breaker according to claim 2, wherein the high-speed analog-to-digital conversion A/D is powered by a 1.8V single power supply, the high-speed analog-to-digital conversion A/D is an 8-channel, 14-bit and 50MSPS analog-to-digital converter, an in-chip sampling and holding circuit is built in, 64-pin LFCSP packaging which meets the RoHS packaging standard is adopted, and the rated temperature range is-40 ℃ to +85 ℃.
8. The on-line monitoring device for the opening and closing time of the circuit breaker according to claim 1, wherein the signal processing and storing unit performs data preprocessing and pre-operation on the received signals and comprises an 8-channel digital sampling interface inside; the signal processing and storing unit can perform data preprocessing and logic pre-operation on the received signals; the signal processing and storing unit also comprises a programmable input/output unit, a programmable logic unit, a clock management unit, an embedded block RAM, an embedded bottom layer functional unit and an embedded special hardware module; the signal processing and storing unit can synchronize clock coding inside, a high-precision clock can generate a time signal with the precision reaching the level of mu s, the signal processing and storing unit can accurately calibrate the trigger time according to the time signal, and the recorded and stored waveform is provided with an accurate time scale; the time signal input is in a 1PPS mode, and the synchronous signal receiving circuit directly receives 1PPS pulses from a GPS synchronous clock; and the signal processing and storing unit is internally provided with SRAM 1-4 which are static random access memories for caching the collected high-frequency voltage and current waveforms.
9. The on-line circuit breaker opening and closing time monitoring device according to claim 8, wherein the signal processing and storing unit sends the preprocessed and preprocessed data signals to the central processing unit for further operation and processing through an internal CAN bus interface.
10. The on-line monitoring device for the opening and closing time of the circuit breaker according to claim 8, wherein the central processing unit is an STM32f407VG type DSC chip and is connected with a state quantity acquisition unit, a display unit, an operation unit and a communication unit; the ARM chip arranged in the central processing unit is provided with a wireless communication interface and an Ethernet communication interface, can generate PWM waves, and can quickly process and output analog quantity, picture signals, control signals and alarm signals.
11. The on-line monitoring device for the opening and closing time of the circuit breaker according to claim 1, wherein the state quantity acquisition unit is connected with the central processing unit through optical coupling isolation, can acquire opening and closing state signals of the on-pole switch in real time and sends the state signals to the central processing unit; the optical coupling isolation adopts a photoelectric coupler; the central processing unit is connected with the remote combat-assisting system through a network card.
12. The on-line monitoring device for the opening and closing time of the circuit breaker according to claim 1, wherein the display unit comprises an indicator lamp and a liquid crystal display screen, and the indicator lamp and the liquid crystal display screen are respectively connected with the central processing unit through optical coupling isolation; the indicating lamp comprises a state indicating lamp, a power supply indicating lamp, a communication indicating lamp, a fault indicating lamp, an operation indicating lamp and a self-checking indicating lamp; the liquid crystal display screen is a human-computer interaction interface and can display the opening and closing time, the opening and closing state and the fault signal of the on-column switch in real time.
13. The on-line circuit breaker opening and closing time monitoring device according to claim 1, wherein the operating unit is connected with the central processing unit through optical coupling isolation, and comprises an upper button, a lower button, a left button, a right button, a cancel button and a confirm button.
14. The on-line monitoring device for the opening and closing time of the circuit breaker according to claim 1, wherein the communication unit comprises a remote communication network port and a USB debugging interface which are connected with a remote master station system; the remote communication network port is connected with the remote master station system, sends signals of the remote communication network port to the master station system and receives various instructions from the master station system; the USB debugging interface is connected with an external computer, and monitors program updating or constant value parameter setting.
15. The on-line monitoring method for the opening and closing time of the circuit breaker is characterized by comprising the following steps of:
comparing the detected line voltage value with a preset voltage value and a preset duration threshold value to judge whether to record waves or not;
step two, simultaneously comparing the detected and collected high-frequency transient current signal value with a preset current integral threshold value and a preset duration value to judge whether wave recording is carried out or not;
thirdly, transmitting the wave recording waveform data to a central processing unit, and simultaneously acquiring and processing opening and closing state signals by the central processing unit;
and step four, the central processing unit sends signals to the master station system/receives various instructions from the master station system.
16. The method for on-line monitoring of closing and opening time of circuit breaker according to claim 15, wherein the first step is performed when the detected line voltage value is detected>8kV and duration>Starting wave recording when the time is 10 s; when the detected line voltage value>8kV and duration T1<At 10s, no recording is performed.
17. The method for on-line monitoring of opening and closing time of circuit breaker according to claim 15, wherein in the second step, the high-frequency transient current signal value>AsetAnd for a time duration<3s, begin recording, locking and storing current>AsetVoltage/current waveforms of a front time period and a rear time period of the time point; when the duration is>At 3s, the recording is not performed, wherein AsetIs a preset threshold value.
18. The method for monitoring the opening and closing time of the circuit breaker according to claim 17, wherein the previous time period and the subsequent time period in the second step are 1s and 2s respectively.
19. The on-line monitoring method for circuit breaker opening and closing time according to claim 15, wherein in the third step, the state signal is collected by a sensor and transmitted to a central processing unit at a high speed.
20. The on-line monitoring method for circuit breaker opening and closing time according to claim 15, wherein the processing of the opening and closing state signals collected in the third step comprises:
when the collected state signal is unchanged, judging that the circuit has transient single-phase earth fault or inrush current or interference caused by other switching-on/off switches at a lower stage;
when the collected state signal is collected and changed from 0 to 1, switching on and switching off at the moment, and calculating the time of the high-frequency voltage waveform recorded at the switching on starting moment, wherein the time window from the voltage initial mutation moment to the voltage stabilization moment is the switching on and switching off time;
and when the collected state signal is collected and changed from 1 to 0, switching on and switching off at the moment, and performing time calculation on the high-frequency current waveform recorded at the starting moment of switching off, wherein the time window from the initial sudden change moment of current to the current stabilization moment is the switching on and switching off time.
21. The method for online monitoring of the opening and closing time of the circuit breaker according to claim 20, wherein in the third step, time calculation is performed on the high-frequency voltage waveform recorded at the opening starting time and the high-frequency current waveform recorded at the opening starting time according to the following equations and conditions:
when a certain collected primary current signal meets the condition that i is more than or equal to isetThen, the current sampling values of the voltage/current waveform data 1s before and 2s after the trigger time are integrated:
wherein i is the value of the collected current signal, isetFor the preset current threshold value, j is the sampling sequence number of the current at the initial moment of each integration period, i.e. the sampling point from the first current is i1The second current sampling point is i2J current sampling point is ijSampling until the Nth sampling point iNEnding, wherein N is the number of sampling points contained in each integration period;
if the absolute value of the numerical integration is larger than or equal to the set value, the opening and closing operation of the circuit breaker can be carried out, namely, the following conditions are met:
|A|≥Aset
wherein A issetFor presetting threshold, when the amplitude of the given high-frequency current is greater than the set threshold, the signal processing and storage unit starts to lock and store the current greater than AsetVoltage current waveform data of the first 1s and the second 2s of the time point, AsetFor a range of current thresholds reached in the event of a fault, AsetThe selection is between 10A and 6300A.
22. The method for monitoring the opening and closing time of the circuit breaker according to claim 15 or 21, wherein the command in step four comprises an opening/closing command, and the opening/closing command is determined according to the following equation and conditions:
if the switching-off time is the switching-off time, the switching-off time is as follows:
Tf＝TIn-TI1
if the switching-on is carried out, the switching-on time is as follows:
Th＝TUn-TU1
wherein, TfFor calculated circuit breaker opening time, ThFor calculated closing time of the circuit breaker, TInThe current recording end time T during openingI1The starting time of current recording during openingUnFor the end time of voltage recording at closing time, TU1The starting time of voltage recording during closing.
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