CN110829372A - Intelligent anti-harmonic-eliminating PT comprehensive protection device and protection method thereof - Google Patents
Intelligent anti-harmonic-eliminating PT comprehensive protection device and protection method thereof Download PDFInfo
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- CN110829372A CN110829372A CN201911096897.1A CN201911096897A CN110829372A CN 110829372 A CN110829372 A CN 110829372A CN 201911096897 A CN201911096897 A CN 201911096897A CN 110829372 A CN110829372 A CN 110829372A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
- H02H7/05—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers for capacitive voltage transformers, e.g. against resonant conditions
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
- H02H7/262—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations involving transmissions of switching or blocking orders
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
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Abstract
The invention discloses an intelligent anti-harmonic and harmonic-eliminating PT comprehensive protection device and a protection method thereof, and relates to the technical field of anti-harmonic and harmonic-eliminating protection control of electromagnetic voltage transformers. The invention adopts the vacuum switch connected in parallel with the silicon carbide nonlinear resistor on the primary side of the anti-saturation PT and the silicon carbide nonlinear resistor and the silicon controlled rectifier on the secondary side of the anti-saturation PT, and realizes the combination of the primary anti-harmonic current limiting and the secondary harmonic elimination, thereby being capable of quickly and effectively inhibiting various PT faults of the system, such as low-frequency resonance, PT inrush current, system resonance and the like.
Description
Technical Field
The invention relates to the technical field of anti-harmonic elimination and protection control of electromagnetic voltage transformers, in particular to an intelligent anti-harmonic elimination PT comprehensive protection device and a protection method thereof.
Background
In a 6-35 kV system with a neutral point not grounded, an electromagnetic voltage transformer (PT for short) for insulation monitoring is connected with a primary winding of the PT into a star shape, and when the system is operated after asynchronous switching-on or ground fault disappears and the like, the excitation impedance of the PT and the ground capacitance of the system form a nonlinear resonance loop. Due to the difference of loop parameters and external excitation conditions, high-frequency, power-frequency and frequency-division resonance overvoltage can be caused, and further frequent faults of PT are caused. For this reason, standards and specifications relating to the power system make clear demands on the protection of PT, such as "overvoltage protection and insulation coordination of DL/T620-1997 ac electrical devices", and "overvoltage protection and insulation coordination design specifications of GB/T50064-2014 ac electrical devices". Even if the power cable is used in a large amount, the single-phase grounding capacitance current is increased, and the PT fault tends to rise, so that the PT fault is a great hidden trouble for safe operation of a power grid.
PT faults mainly manifest in two forms, namely high voltage (primary) winding burn-out and high voltage fuse blow-out. In early researches, PT faults are attributed to PT ferromagnetic resonance, but simulation calculation and laboratory resonance excitation of PT prove that currents in resonance cannot fuse a PT high-voltage fuse, and capacitor discharge impact inrush currents in recovery of single-phase earth faults are the main reasons for fuse fusing.
In order to prevent PT faults from occurring as much as possible, many protection schemes have been proposed in the past several decades. In addition to improving the performance parameters of the PT itself, these protective measures are mainly classified into primary anti-harmonic current limiting and secondary harmonic elimination. The primary anti-harmonic current limiting mainly comprises a 4PT method and a nonlinear resistance method; the second harmonic elimination mainly comprises two methods of open-delta resistance damping and direct short circuit. The methods are based on different principles, have respective advantages and irreplaceable functions, are widely applied to power systems, but have respective defects and problems in operation practice, and cannot be effectively integrated to achieve advantage complementation to form a complete solution.
Disclosure of Invention
In order to solve the problems, the invention provides an intelligent anti-harmonic and harmonic-eliminating PT comprehensive protection device and a protection method thereof, and the specific technical scheme is as follows:
an intelligent anti-harmonic and harmonic-eliminating PT comprehensive protection device comprises a signal conditioning unit, a micro-processing unit, a protection control unit, a state indicating unit, a remote communication unit, an external storage unit, a power management unit and a silicon carbide nonlinear resistor, wherein the protection control unit comprises a vacuum switch, an intermediate relay and a silicon controlled rectifier; the vacuum switch is connected with the controllable silicon through an intermediate relay,
the signal conditioning unit, the protection control unit, the state indicating unit, the remote communication unit, the external storage unit and the power management unit are respectively connected with the micro-processing unit, and the silicon carbide nonlinear resistor is connected with the protection control unit;
the signal conditioning unit is used for conditioning a voltage signal output by a secondary side of an electromagnetic voltage transformer PT to a proper range and then sending the voltage signal to the micro-processing unit, the micro-processing unit is used for acquiring the voltage signal output by the signal conditioning unit in real time, transmitting the acquired voltage signal to the external storage unit, outputting a corresponding control signal after calculating and analyzing according to the acquired voltage signal, and transmitting the control signal to the protection control unit, the external storage unit is used for storing the voltage signal transmitted by the micro-processing unit, the protection control unit controls the on or off of the vacuum switch and the controllable silicon according to the control signal transmitted by the micro-processing unit, and the state indicating unit is used for displaying the running state, the communication mode and the fault type of the device and sending an alarm signal. And alarm output is carried out on corresponding abnormal conditions; the remote communication unit is used for receiving an instruction of a remote system, transmitting the instruction to the micro-processing unit and sending monitoring data of the micro-processing unit to the remote system; the power management module is used for supplying power to the signal conditioning unit, the micro-processing unit, the protection control unit, the state indicating unit, the remote communication unit and the external storage unit.
Furthermore, the signal conditioning unit comprises a current type voltage transformer, and the current type voltage transformer is used for converting and adjusting the three-phase voltage signals and the open-delta voltage to a proper range, and transmitting the three-phase voltage signals and the open-delta voltage in the proper range to the micro-processing unit for sampling.
Further, the microprocessor unit adopts an STM32F103VGT6 microprocessor based on a CORTEX-M332 bit RISC core.
Further, the state indicating unit comprises an LED indicating lamp and a buzzer, the LED indicating lamp and the buzzer are connected with the microprocessor unit in a resistance pull-up mode, the LED indicating lamp is used for displaying the running state, the communication mode and the fault type of the device, and the buzzer is used for sending out an alarm signal.
Further, the remote communication unit comprises an RS-485 serial protocol module, a WIFI module and a remote communication module, wherein the RS-485 serial protocol module adopts a +3.3V low-power-consumption half-duplex transceiver with the model number of SP3485EN, the WIFI module adopts an E103-W01 module, and the remote communication module adopts an ml5510 module.
Further, the external storage unit comprises a TF card slot and an SD card, the SD card is inserted into the TF card slot, and the SD card is used for storing all fault information and events transmitted by the micro-processing unit.
Further, the power management unit converts the alternating current 220VAC voltage into 12V and 5V voltage through the voltage conversion module for use by the device.
The invention also comprises a protection method of the intelligent anti-harmonic and harmonic-eliminating PT comprehensive protection device, which comprises the following steps:
step S1, an electromagnetic voltage transformer PT monitors open triangle voltage and three-phase voltage, and outputs the open triangle voltage and the three-phase voltage to a signal conditioning unit through a secondary side of the electromagnetic voltage transformer PT;
step S2, the signal conditioning unit conditions the open triangle voltage and the three-phase voltage output by the secondary side of the electromagnetic voltage transformer PT to a proper range and then sends the regulated open triangle voltage and the three-phase voltage to the micro-processing unit;
step S3, the micro-processing unit collects the open delta voltage and the three-phase voltage output by the signal conditioning unit in real time, transmits the collected open delta voltage and the collected three-phase voltage to an external storage unit, calculates and analyzes the collected open delta voltage and the collected three-phase voltage, and outputs a corresponding control signal to the protection control unit;
step S4, the external storage unit stores the open triangle voltage and the three-phase voltage transmitted by the micro-processing unit, the protection control unit controls the on or off of the vacuum switch and the controllable silicon according to the control signal transmitted by the micro-processing unit, the state indication unit displays the running state, the communication mode and the fault type of the micro-processing unit, and alarms and outputs corresponding abnormal conditions;
and step S5, the data transmission of the remote communication unit is bidirectional transmission, receives the instruction of the remote system, transmits the instruction to the micro-processing unit, and sends the monitoring data of the micro-processing unit to the remote system.
Further, the three-phase grid system is protected by the following method:
1) if the system runs normally, the three-phase voltage and the open triangular voltage are normal, the micro-processing unit starts the input vacuum switch, bypasses the silicon carbide nonlinear resistor and provides a high-power quality voltage signal for the metering and measuring and controlling device;
2) if the system has single-phase earth fault, the voltage drop of the fault phase is zero, the voltage of the non-fault phase is increased to the line voltage, the voltage of 100V is measured at the opening triangle, and the device judges that PT inrush current occurs, the micro-processing unit starts to disconnect a vacuum switch, a silicon carbide nonlinear resistor is put into the vacuum switch, the ground recovery inrush current is inhibited, and the system is waited to run normally and automatically reset;
3) if the voltage transformer generates ferromagnetic resonance, a neutral point generates displacement to enable three-phase voltage to be asymmetric, the voltage transformer is saturated ferromagnetically and generates zero-sequence magnetic flux, a high-voltage winding flows through zero-sequence current, zero-sequence voltage can be induced at two ends of an opening triangle, the micro-processing unit judges that low-frequency resonance occurs, the micro-processing unit starts secondary 0-300 Hz silicon controlled full-frequency resonance elimination, the demagnetization effect is achieved through the established magnetic flux, when the silicon controlled is conducted, zero-sequence current flows, the larger the secondary zero-sequence current is, the better the demagnetization effect is, the best effect is achieved in short circuit, and the voltage transformer is in a short circuit state for a long time and; when the short circuit state runs for more than 1s, the silicon controlled rectifier resonates, the micro-processing unit collects data, the silicon controlled rectifier is conducted after the normal voltage value is exceeded, the resonance is eliminated instantly, and the silicon controlled rectifier restores the blocking state after the resonance disappears;
4) if the silicon controlled rectifier is conducted and operated for more than 1s, the resonance is still not eliminated, the micro-processing unit judges that the system is in resonance, the micro-processing unit starts to disconnect a vacuum switch, a silicon carbide nonlinear resistor is put into the micro-processing unit, the silicon controlled rectifier keeps a blocking state, the system resonance is inhibited, and the system is waited to operate normally and automatically reset;
5) if the voltage transformer has a disconnection fault, the voltage of a fault phase is reduced to zero, the voltage of a non-fault phase is normal, the voltage exists in the opening triangle, and the microprocessing unit judges that the disconnection fault occurs, and does not perform any operation.
The invention has the beneficial effects that:
the invention adopts the vacuum switch connected in parallel with the silicon carbide nonlinear resistor on the primary side of the anti-saturation PT and the silicon carbide nonlinear resistor and the silicon controlled rectifier on the secondary side of the anti-saturation PT, and realizes the combination of the primary anti-harmonic current limiting and the secondary harmonic elimination, thereby being capable of quickly and effectively inhibiting various PT faults of the system, such as low-frequency resonance, PT inrush current, system resonance and the like.
Drawings
Fig. 1 is a schematic diagram of the structure of the present invention.
Fig. 2 is a schematic diagram of a signal conditioning unit of the present invention.
Fig. 3 is a schematic diagram of the protection control unit of the present invention.
FIG. 4 is a schematic diagram of the "electro-optic-electro" conversion of the present invention.
Detailed Description
For a better understanding of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings in which:
as shown in fig. 1, an intelligent anti-harmonic and harmonic-eliminating PT comprehensive protection device includes a signal conditioning unit, a microprocessor unit, a protection control unit, a state indication unit, a remote communication unit, an external storage unit, a power management unit, and a silicon carbide nonlinear resistor;
as shown in fig. 3, the protection control unit includes a vacuum switch, an intermediate relay, and a thyristor, the vacuum switch is connected with the thyristor through the intermediate relay, the silicon carbide nonlinear resistor is connected with the protection control unit,
the device comprises a signal conditioning unit, a protection control unit, a state indicating unit, a remote communication unit, an external storage unit and a power management unit which are respectively connected with a micro-processing unit, wherein the signal conditioning unit is used for conditioning a voltage signal output by a secondary side of an electromagnetic voltage transformer PT to a proper range and then sending the voltage signal to the micro-processing unit, the micro-processing unit is used for acquiring the voltage signal output by the signal conditioning unit in real time, transmitting the acquired voltage signal to the external storage unit, calculating and analyzing the acquired voltage signal and then outputting a corresponding control signal, and transmitting the control signal to the protection control unit, the external storage unit is used for storing the voltage signal transmitted by the micro-processing unit, the protection control unit controls the on or off of a vacuum switch and a controllable silicon according to the control signal transmitted by the micro-processing unit, and the state indicating unit is used for outputting the running state of the device, the indication lamp is used for displaying and alarming and outputting corresponding abnormal conditions; the remote communication unit is used for receiving an instruction of a remote system, transmitting the instruction to the micro-processing unit and sending monitoring data of the micro-processing unit to the remote system; the power management module is used for supplying power to the signal conditioning unit, the micro-processing unit, the protection control unit, the state indicating unit, the remote communication unit and the external storage unit.
As shown in fig. 2, the signal conditioning unit of the invention includes a resistor R50, a resistor R51, a resistor R52, a resistor R53, a current-type voltage transformer, a capacitor C50, a resistor R50, a resistor R51, a resistor R52, and a resistor R53, which are respectively connected with the current-type voltage transformer, a capacitor C50 is connected with the resistor R53, the resistors R50 and R51 are both 56k Ω, the resistor R52 is 470 Ω, the resistor R53 is 1.2k Ω, the current-type voltage transformer adopts a current-type voltage transformer TV31B02 from samsung electronics company, the microprocessor unit of the invention adopts an STM32F103VGT6 microprocessor based on a core x-M332 bit core RISC, the operating frequency is 72 MHz, a high-speed embedded memory (FLASH is up to 1 MB, SRAM is up to 96 KB), and various enhanced I/O and peripheral devices connected with two APB buses, the STM32F 103F 6 provides three-bit input channel converters (multiple ADC 21-ADC), the ADC converter is for AD sampling, ten general 16-bit timers and two PWM timers, and standard and advanced communication interfaces: a maximum of two I2C, three SPIs, two I2S, one SDIO, five USARTs, one USB and one CAN.
A voltage signal Ua output by a secondary side of the electromagnetic voltage transformer PT of the invention is subjected to signal conversion and low-pass filtering to reach an appropriate range A1 and is sent to the microprocessing unit for AD sampling, and the signal conditioning unit is used for performing signal conversion and low-pass filtering on three-phase voltage and open-delta voltage signals.
The protection control unit controls a vacuum switch connected in parallel with a silicon carbide nonlinear resistor and a silicon controlled rectifier added in an open triangular loop, the alternating current type vacuum switch is driven by an intermediate relay, the relay is driven by a triode 8050, the silicon controlled rectifier is driven by an optical coupler MOC3081, light is used as a medium to transmit an electric signal, when an input end is powered on with a signal, a light emitter emits light, and a light receiver generates photocurrent after receiving the light and flows out from an output end, so that 'electricity-light-electricity' conversion is realized.
The state indicating unit comprises 8 LED indicating lamps and 1 buzzer, wherein the LED indicating lamps and the buzzer are all in a resistance pull-up mode, the micro-processing unit can be driven correspondingly by adopting low voltage, the 8 LED indicating lamps and the 1 buzzer have the specific functions shown in table 1, the LED indicating lamps and the buzzer are both connected with the micro-processing unit in a resistance pull-up mode, the LED indicating lamps are used for displaying the running state, the communication mode and the fault type of the device, and the buzzer is used for sending out an alarm signal.
Function table with 18 LED indicator lamps and 1 buzzer
The remote communication unit comprises an RS-485 serial protocol module, a WIFI module and a remote communication module, wherein the RS-485 serial protocol module adopts a +3.3V low-power consumption half-duplex transceiver with the model number of SP3485EN, the WIFI module adopts an E103-W01 module developed by Espriff corporation based on an ESP8266EX chip of Chengdu Baite electronics technology company Limited, and the remote communication module adopts a ml5510 module of low-power consumption wide area internet of things technology of Qi Jun corporation;
the RS-485 serial protocol module function is used for networking with other equipment or systems and is isolated by an optocoupler chip TLP 785; the WIFI module is used for connecting a handheld special PDA or a tablet personal computer with the device, checking the running state and historical data of the device, realizing the functions of displaying real-time data and the current state, counting information, browsing events, inquiring historical data, setting parameters and the like, and integrates a transparent transmission function, namely, the function of taking and using the WIFI module, supporting a serial port AT instruction set and a server AT instruction set, and a user can use a network access function through a serial port and simultaneously supports AirKiss; the remote communication module is connected to a remote background through 2G/3G/4G remote communication, so that data can be viewed at a remote end, various communication modes of 2G GPRS/NB-IOT/4G LET can be realized, and the application requirements of the Internet of things of the intelligent anti-harmonic-elimination PT comprehensive protection device can be met.
The external storage unit comprises a TF card slot and an SD card, wherein the SD card is inserted into the TF card slot and used for storing all fault information and events transmitted to the external storage unit by the micro-processing unit, so that power failure loss is prevented.
The power management unit is used for managing a working power supply of the whole device and needs to manage various voltage grades, including direct current 1.8V, 3.3V, 5V, 12V and alternating current 220VAC, alternating current 220V voltage is provided outside and is converted into 12V and 5V voltage through a voltage conversion module for use by the device, AMS1117-3.3 chip is adopted to convert 5V voltage into 3.3V voltage, XC6206-1.8V chip is adopted to convert 5V voltage into 1.8V voltage, wherein 1.8V is used as reference voltage for AD sampling, 5V voltage and 3.3V voltage are used for a micro-processing unit, an AMS1117-3.3 chip and an XC6206-1.8V chip, 12V voltage is used for a relay and a remote communication circuit, and a built-in battery is used for supplying power for the micro-processing unit and the remote communication unit so as to ensure that the device can still send and receive data in a short time after power failure.
The invention adopts the vacuum switch connected in parallel with the silicon carbide nonlinear resistor on the primary side of the anti-saturation PT and the silicon carbide nonlinear resistor and the silicon controlled rectifier on the secondary side of the anti-saturation PT, and realizes the combination of the primary anti-harmonic current limiting and the secondary harmonic elimination, thereby being capable of quickly and effectively inhibiting various PT faults of the system, such as low-frequency resonance, PT inrush current, system resonance and the like.
The invention also comprises a protection method of the intelligent anti-harmonic and harmonic-eliminating PT comprehensive protection device, which comprises the following steps:
and step S1, the electromagnetic voltage transformer PT monitors the open triangular voltage and the three-phase voltage, and outputs the open triangular voltage and the three-phase voltage to the signal conditioning unit through the secondary side of the electromagnetic voltage transformer PT.
And step S2, the signal conditioning unit conditions the open triangle voltage and the three-phase voltage output by the secondary side of the electromagnetic voltage transformer PT to a proper range and then sends the regulated open triangle voltage and the three-phase voltage to the micro-processing unit.
And step S3, the micro-processing unit collects the open delta voltage and the three-phase voltage output by the signal conditioning unit in real time, transmits the collected open delta voltage and the collected three-phase voltage to an external storage unit, calculates and analyzes the collected open delta voltage and the collected three-phase voltage, and outputs a corresponding control signal to the protection control unit.
And step S4, the external storage unit stores the open-delta voltage and the three-phase voltage transmitted by the micro-processing unit, the protection control unit controls the on or off of the vacuum switch and the controllable silicon according to the control signal transmitted by the micro-processing unit, and the state indicating unit displays the output running state of the micro-processing unit and gives an alarm for outputting corresponding abnormal conditions.
And step S5, the data transmission of the remote communication unit is bidirectional transmission, receives the instruction of the remote system, transmits the instruction to the micro-processing unit, and sends the monitoring data of the micro-processing unit to the remote system.
The invention relates to a protection method of an intelligent anti-harmonic and harmonic-eliminating PT comprehensive protection device, which judges the nature of a fault according to the characteristics of fault voltage and sends out corresponding control for protection, and the protection method specifically comprises the following steps:
1) if the system runs normally, the three-phase voltage and the open triangular voltage are normal, the micro-processing unit starts the input vacuum switch, bypasses the silicon carbide nonlinear resistor and provides a high-power quality voltage signal for the metering and measuring and controlling device.
2) If the system has single-phase earth fault, the voltage drop of the fault phase is zero, the voltage of the non-fault phase is increased to the line voltage, the voltage of 100V is measured at the opening triangle, and the device judges that PT inrush current occurs, the micro-processing unit starts to disconnect the vacuum switch, a silicon carbide nonlinear resistor is put into the vacuum switch, the earth recovery inrush current is restrained, and the system is waited to run normally and automatically reset.
3) If the voltage transformer generates ferromagnetic resonance, a neutral point generates displacement to enable three-phase voltage to be asymmetric, the voltage transformer is saturated ferromagnetically and generates zero-sequence magnetic flux, a high-voltage winding flows through zero-sequence current, zero-sequence voltage can be induced at two ends of an opening triangle, the micro-processing unit judges that low-frequency resonance occurs, the micro-processing unit starts secondary 0-300 Hz silicon controlled full-frequency resonance elimination, the demagnetization effect is achieved through the established magnetic flux, when the silicon controlled is conducted, zero-sequence current flows, the larger the secondary zero-sequence current is, the better the demagnetization effect is, the best effect is achieved in short circuit, and the voltage transformer is in a short circuit state for a long time and; when the short circuit state runs for more than 1s, the silicon controlled rectifier resonates, the micro-processing unit collects data, the silicon controlled rectifier is conducted after the data exceed a normal voltage value, the resonance is eliminated instantly, and the silicon controlled rectifier restores the blocking state after the resonance disappears.
4) If the silicon controlled rectifier is conducted and operated for more than 1s, the resonance is still not eliminated, the micro-processing unit judges that the system is in resonance, the micro-processing unit starts to disconnect the vacuum switch, the silicon carbide nonlinear resistor is put into use, the silicon controlled rectifier keeps a blocking state, the system resonance is restrained, and the system is waited to operate normally and automatically reset.
5) If the voltage transformer has a disconnection fault, the voltage of a fault phase is reduced to zero, the voltage of a non-fault phase is normal, the voltage exists in the opening triangle, and the microprocessing unit judges that the disconnection fault occurs, and does not perform any operation.
The present invention is not limited to the above embodiments, which are merely preferred embodiments of the present invention, and the present invention is not limited thereto, and any modifications, equivalents and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. An intelligent anti-harmonic and harmonic-eliminating PT comprehensive protection device is characterized by comprising a signal conditioning unit, a micro-processing unit, a protection control unit, a state indicating unit, a remote communication unit, an external storage unit, a power management unit and a silicon carbide nonlinear resistor, wherein the protection control unit comprises a vacuum switch, an intermediate relay and a silicon controlled rectifier; the vacuum switch is connected with the controllable silicon through an intermediate relay,
the signal conditioning unit, the protection control unit, the state indicating unit, the remote communication unit, the external storage unit and the power management unit are respectively connected with the micro-processing unit, and the silicon carbide nonlinear resistor is connected with the protection control unit;
the signal conditioning unit is used for conditioning a voltage signal output by a secondary side of an electromagnetic voltage transformer PT to a proper range and then sending the voltage signal to the micro-processing unit, the micro-processing unit is used for acquiring the voltage signal output by the signal conditioning unit in real time, transmitting the acquired voltage signal to the external storage unit, outputting a corresponding control signal after calculation and analysis according to the acquired voltage signal and transmitting the control signal to the protection control unit, the external storage unit is used for storing the voltage signal transmitted by the micro-processing unit, the protection control unit controls the on or off of the vacuum switch and the controllable silicon according to the control signal transmitted by the micro-processing unit, and the state indicating unit is used for displaying the running state, the communication mode and the fault type of the device and alarming and outputting corresponding abnormal conditions; the remote communication unit is used for receiving an instruction of a remote system, transmitting the instruction to the micro-processing unit and sending monitoring data of the micro-processing unit to the remote system; the power management module is used for supplying power to the signal conditioning unit, the micro-processing unit, the protection control unit, the state indicating unit, the remote communication unit and the external storage unit.
2. The intelligent anti-harmonic-eliminating PT comprehensive protection device as claimed in claim 1, wherein the signal conditioning unit comprises a current type voltage transformer for transforming and adjusting three-phase voltage signals and open delta voltage to a proper range, and transmitting the three-phase voltage signals and the open delta voltage of the proper range to the micro processing unit for sampling.
3. An intelligent anti-harmonic PT comprehensive protection device as claimed in claim 1, wherein said microprocessor unit adopts an STM32F103VGT6 microprocessor based on CORTEX-M332 bit RISC kernel.
4. The intelligent anti-harmonic-eliminating PT comprehensive protection device as claimed in claim 1, wherein said status indication unit comprises an LED indicator light and a buzzer, both of said LED indicator light and said buzzer are connected with said microprocessor unit in a resistance pull-up manner, said LED indicator light is used for displaying the operation status, communication manner and fault type of the device, and said buzzer is used for sending an alarm signal.
5. The intelligent anti-harmonic-elimination PT comprehensive protection device as claimed in claim 1, wherein the remote communication unit comprises an RS-485 serial protocol module, a WIFI module and a remote communication module, the RS-485 serial protocol module adopts a +3.3V low-power consumption half-duplex transceiver with model number SP3485EN, the WIFI module adopts an E103-W01 module, and the remote communication module adopts a ml5510 module.
6. An intelligent anti-harmonic PT comprehensive protection device according to claim 1, characterized in that said external storage unit comprises TF card slot, SD card, said SD card is inserted into TF card slot, said SD card is used to store all fault information and events transmitted by micro-processing unit.
7. The intelligent anti-harmonic PT comprehensive protection device as claimed in claim 1, wherein the power management unit converts an alternating current 220VAC voltage into 12V and 5V voltages for use by a device through a voltage conversion module.
8. A protection method of an intelligent anti-harmonic and harmonic-eliminating PT comprehensive protection device is characterized by comprising the following steps:
step S1, an electromagnetic voltage transformer PT monitors open triangle voltage and three-phase voltage, and outputs the open triangle voltage and the three-phase voltage to a signal conditioning unit through a secondary side of the electromagnetic voltage transformer PT;
step S2, the signal conditioning unit conditions the open triangle voltage and the three-phase voltage output by the secondary side of the electromagnetic voltage transformer PT to a proper range and then sends the regulated open triangle voltage and the three-phase voltage to the micro-processing unit;
step S3, the micro-processing unit collects the open delta voltage and the three-phase voltage output by the signal conditioning unit in real time, transmits the collected open delta voltage and the collected three-phase voltage to an external storage unit, calculates and analyzes the collected open delta voltage and the collected three-phase voltage, and outputs a corresponding control signal to the protection control unit;
step S4, the external storage unit stores the open triangle voltage and the three-phase voltage transmitted by the micro-processing unit, the protection control unit controls the on or off of the vacuum switch and the controllable silicon according to the control signal transmitted by the micro-processing unit, the state indication unit displays the running state, the communication mode and the fault type of the micro-processing unit, and alarms and outputs corresponding abnormal conditions;
and step S5, the data transmission of the remote communication unit is bidirectional transmission, receives the instruction of the remote system, transmits the instruction to the micro-processing unit, and sends the monitoring data of the micro-processing unit to the remote system.
9. The protection method of the intelligent anti-harmonic and harmonic-eliminating PT comprehensive protection device according to claim 8,
the three-phase grid system is protected by the following method:
1) if the system runs normally, the three-phase voltage and the open triangular voltage are normal, the micro-processing unit starts the input vacuum switch, bypasses the silicon carbide nonlinear resistor and provides a high-power quality voltage signal for the metering and measuring and controlling device;
2) if the system has single-phase earth fault, the voltage drop of the fault phase is zero, the voltage of the non-fault phase is increased to the line voltage, the voltage of 100V is measured at the opening triangle, and the device judges that PT inrush current occurs, the micro-processing unit starts to disconnect a vacuum switch, a silicon carbide nonlinear resistor is put into the vacuum switch, the ground recovery inrush current is inhibited, and the system is waited to run normally and automatically reset;
3) if the voltage transformer generates ferromagnetic resonance, a neutral point generates displacement to enable three-phase voltage to be asymmetric, the voltage transformer is saturated ferromagnetically and generates zero-sequence magnetic flux, a high-voltage winding flows through zero-sequence current, zero-sequence voltage can be induced at two ends of an opening triangle, the micro-processing unit judges that low-frequency resonance occurs, the micro-processing unit starts secondary 0-300 Hz silicon controlled full-frequency resonance elimination, the demagnetization effect is achieved through the established magnetic flux, when the silicon controlled is conducted, zero-sequence current flows, the larger the secondary zero-sequence current is, the better the demagnetization effect is, the best effect is achieved in short circuit, and the voltage transformer is in a short circuit state for a long time and; when the short circuit state runs for more than 1s, the silicon controlled rectifier resonates, the micro-processing unit collects data, the silicon controlled rectifier is conducted after the normal voltage value is exceeded, the resonance is eliminated instantly, and the silicon controlled rectifier restores the blocking state after the resonance disappears;
4) if the silicon controlled rectifier is conducted and operated for more than 1s, the resonance is still not eliminated, the micro-processing unit judges that the system is in resonance, the micro-processing unit starts to disconnect a vacuum switch, a silicon carbide nonlinear resistor is put into the micro-processing unit, the silicon controlled rectifier keeps a blocking state, the system resonance is inhibited, and the system is waited to operate normally and automatically reset;
5) if the voltage transformer has a disconnection fault, the voltage of a fault phase is reduced to zero, the voltage of a non-fault phase is normal, the voltage exists in the opening triangle, and the microprocessing unit judges that the disconnection fault occurs, and does not perform any operation.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111813000A (en) * | 2020-06-11 | 2020-10-23 | 广西电网有限责任公司电力科学研究院 | Method and device for simulating ferromagnetic resonance of power distribution network real-time test platform |
| CN111856205A (en) * | 2020-06-19 | 2020-10-30 | 南方电网科学研究院有限责任公司 | Power distribution network fault indication system and method |
| CN112039038A (en) * | 2020-08-24 | 2020-12-04 | 国网河北省电力有限公司邯郸供电分公司 | Voltage transformer resonance active elimination method based on energy release |
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2019
- 2019-11-11 CN CN201911096897.1A patent/CN110829372A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111813000A (en) * | 2020-06-11 | 2020-10-23 | 广西电网有限责任公司电力科学研究院 | Method and device for simulating ferromagnetic resonance of power distribution network real-time test platform |
| CN111856205A (en) * | 2020-06-19 | 2020-10-30 | 南方电网科学研究院有限责任公司 | Power distribution network fault indication system and method |
| CN112039038A (en) * | 2020-08-24 | 2020-12-04 | 国网河北省电力有限公司邯郸供电分公司 | Voltage transformer resonance active elimination method based on energy release |
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