Disclosure of Invention
The invention aims to provide a transformer area identification instrument capable of quickly and accurately identifying a transformer area.
In order to achieve the purpose, the invention adopts the following technical solutions:
a station area identifier, comprising: the signal transmitting module is used for generating a dynamic characteristic current signal which has a variable frequency constant amplitude and cuts a power frequency sine wave on a power grid line, is arranged at an ammeter end of a power grid system and is connected with a zero line and a live line of the power grid system; with signal transmission module communication connection's signal reception module, signal reception module sets up in electric wire netting system transformer end, signal reception module includes signal acquisition unit, signal processing unit and does the power supply unit of signal acquisition unit and signal processing power supply, the signal acquisition unit sets up on the triphase line of electric wire netting circuit, the signal acquisition unit is magnetic field sensor for gather the magnetic field information that dynamic characteristic current signal produced among the electric wire netting circuit and give signal processing unit, signal processing unit is used for receiving and comes from the magnetic field information of signal acquisition unit output to calculate the pulse semaphore, carry out the platform district discernment.
As a specific embodiment of the station area identifier of the invention, the signal transmission module comprises a first main control MCU, a load switching circuit connected with the first main control MCU, a dynamic load control circuit connected with the first main control MCU, a first communication circuit connected with the first main control MCU and a power supply circuit for supplying power to the circuits, the load switching circuit is connected with a zero line and a live line of a power grid system and is used for generating dynamic characteristic current signals on the power grid line, the dynamic control circuit is connected with the load switching circuit and is used for adjusting the size of a dynamic characteristic current signal generated by the load switching circuit, the first main control MCU is used for controlling the load switching circuit to work according to the number of zero point pulse signals on a power grid, the first communication circuit is used for realizing the communication connection between the signal sending module and the signal receiving module.
As a specific embodiment of the station area identifier, the load switching circuit includes a high-pass filter circuit, a gate driver, a weak current protection circuit, an insulated gate bipolar transistor, a load resistor, and a full-wave rectifier circuit, a dc output end of the full-wave rectifier circuit is connected to a live line and a zero line of a power grid line, a high-frequency PWM signal generated by the first main control MCU is output to the high-pass filter circuit for filtering, and then sequentially passes through the gate driver and the weak current protection circuit to drive the insulated gate bipolar transistor, and then a characteristic current signal is generated by the load resistor and the full-wave rectifier circuit and output to the power grid line.
As a specific embodiment of the station area identifier according to the present invention, a gate of the insulated gate bipolar transistor is connected to an output terminal of the weak current protection circuit, an emitter of the insulated gate bipolar transistor is grounded, a collector of the insulated gate bipolar transistor is connected to the load resistor, the load resistor is composed of a plurality of resistors, the load resistor is connected to one ac input terminal of the full-wave rectification circuit, and another ac input terminal of the full-wave rectification circuit is grounded.
As a specific embodiment of the station area identifier of the present invention, the dynamic load control circuit includes at least one control branch circuit composed of a triode and a solid-state relay driven by the triode, one end of the control branch circuit is connected to the first main control MCU, and the other end is connected to the load switching circuit, and is connected between a load resistor and a full-wave rectification circuit of the load switching circuit, so as to adjust the magnitude of the dynamic characteristic current.
As a specific embodiment of the platform area identifier of the present invention, the signal acquisition unit includes multiple signal acquisition channels, each signal acquisition channel corresponds to a phase line in the power grid system, and each signal acquisition channel includes a TMR sensor, an instrument amplification circuit, a high-pass filter circuit, and a first band-pass filter circuit, which are connected in sequence.
As a specific embodiment of the station area identifier of the present invention, the signal processing unit includes a signal processing channel corresponding to the signal acquisition channel, a second main control MCU and a second communication circuit, the second main control MCU is connected to the signal processing channel and the second communication circuit, and each of the signal processing channels includes a second band-pass filter circuit, a linear amplifier circuit and a signal shaping circuit, which are sequentially connected.
As a specific embodiment of the station area identifier of the present invention, the signal shaping circuit is a voltage comparator.
As a specific embodiment of the station area identifier of the present invention, the signal transmission module further includes a buzzer circuit and a liquid crystal display circuit connected to the first main control MCU.
As a specific embodiment of the station area identifier of the present invention, the signal processing unit further includes an electric quantity display circuit and a buzzer circuit connected to the second main control MCU.
According to the technical scheme, the current signal of the characteristic current signal of the power frequency sine wave with variable frequency constant amplitude and cutting is generated on the power network line by the sending end through the signal sending module and is used as the dynamic characteristic current signal, the dynamic characteristic current signal is acquired by the receiving end through the magnetic field sensor based on the magnetic field information, the whole station area identification process can be rapidly completed through real-time communication between the signal sending module and the signal receiving module in the station area identification process, the problem of phase crosstalk can be solved by matching with a dynamic load switching mechanism, and the method can be applied to station area attribution and network topology determination of users. Especially, when the TMR sensor is used for acquiring magnetic field information generated by a current signal in a preferred technical scheme, the TMR sensor has high sensitivity, can detect a tiny magnetic field change (namely, current change), and the sensitivity and the signal-to-noise ratio of the TMR sensor are in an inverse correlation relationship, the higher the sensitivity of the TMR sensor, the lower the signal-to-noise ratio, and is especially suitable for the situation that the signal-to-noise ratio at a receiving end (a distribution room or a branch box) is lower when a sending end switches current of an electric energy meter with a larger load, a larger noise and a longer power line length, even if the switching current is small, the current signal can be accurately identified, and thus the platform area identification can be accurately carried out.
Drawings
In order to illustrate the embodiments of the present invention more clearly, the drawings that are needed in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained by those skilled in the art without inventive effort.
FIG. 1 is a block diagram of a circuit of a zone area identifier according to an embodiment of the present invention;
FIG. 2 is a block diagram of a signal transmitting module according to an embodiment of the present invention;
FIG. 3 is a circuit diagram of a strong current filter circuit according to an embodiment of the present invention;
FIG. 4 is a circuit diagram of a switching power supply circuit according to an embodiment of the present invention;
FIG. 5 is a diagram of a first MCU and its peripheral circuits according to an embodiment of the present invention;
FIG. 6 is a circuit diagram of a LORA communication circuit according to an embodiment of the present invention;
FIG. 7 is a circuit diagram of a buzzer circuit according to an embodiment of the present invention;
FIG. 8 is a circuit diagram of an LCD circuit according to an embodiment of the present invention;
fig. 9 is a circuit diagram of a load switching circuit according to an embodiment of the present invention;
FIG. 10 is a circuit diagram of a dynamic load control circuit according to an embodiment of the present invention;
FIG. 11 is a block diagram of a signal receiving module according to an embodiment of the invention;
FIG. 12 is a circuit diagram of a meter amplification circuit according to an embodiment of the present invention;
FIG. 13 is a circuit diagram of a first band pass filter circuit according to an embodiment of the present invention;
FIG. 14 is a circuit diagram of a second band-pass filter circuit according to an embodiment of the present invention;
FIG. 15 is a circuit diagram of a linear amplification circuit according to an embodiment of the present invention;
fig. 16 is a circuit diagram of a signal shaping circuit according to an embodiment of the invention.
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Detailed Description
In order to make the aforementioned and other objects, features and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
As shown in fig. 1, the station area identifier of the present embodiment includes a signal sending module 1, a signal processing unit 2, and a signal acquiring unit 3. The signal transmitting module 1 is arranged at an ammeter end of a power grid system, is connected with a live wire and a zero line in a power grid line and is used for generating dynamic characteristic current signals on the power grid line, the signal processing unit 2 and the signal acquisition unit 3 form a signal receiving module, the signal receiving module is arranged at a transformer end of the power grid system, and the signal transmitting module and the signal receiving module are in communication connection through a wireless communication module. The signal acquisition units 3 are arranged on three phase lines (A/B/C) of a power grid line at the transformer end, and the signal acquisition units 3 are used for acquiring magnetic fields generated by dynamic characteristic current signals in the power grid line and outputting the acquired magnetic field signals to the signal processing unit 2 through non-contact magnetic field induction. The signal processing unit 2 extracts pulse semaphore from the signal received from the signal acquisition unit 3, and realizes the identification of the electric meter region relation.
The dynamic characteristic current signal generated by the signal sending module is a current signal with constant frequency and variable amplitude and cutting power frequency sine wave. The constant frequency of the current signal refers to the condition that the switching frequency of a sending end is consistent with the central frequency point of a band-pass filter of a receiving end, and the variable amplitude refers to the condition that switching currents of different grades generate current signals with different amplitudes.
The zero-point signal quantities of different areas are different due to factors such as noise, load size and power line length, and the pulse signal quantities received by the receiving end of the same area are different when the same electric energy meter carries out load switching in different time periods. The power grid is a variable, and the test objects (different electric energy meters) of the station area identification instrument are also variables, so that the dynamic characteristic current signal with variable amplitude can be adapted to wider station areas and more test objects, and the switching currents with different levels can be used for avoiding that data cannot be identified (namely the data has no obvious difference) or even the phase misjudgment caused by the phenomenon of 'phase string' due to the fact that excessive current is switched in part of the station areas.
As shown in fig. 2, the signal sending module 1 of this embodiment includes a power supply circuit, a load switching circuit, a dynamic load control circuit, a first main control MCU and a first communication circuit, and in a preferred embodiment, the signal sending module 1 may further include a liquid crystal display circuit and a buzzer circuit. The power supply circuit is used for supplying power to all circuits in the signal transmitting module 1, the load switching circuit is used for generating dynamic characteristic current signals on a power grid line, the dynamic load control circuit is used for adjusting the size of the characteristic current signals, the first main control MCU is used for controlling the working state of all circuits in the signal transmitting module 1, the communication circuit is used for achieving data interaction between the signal transmitting module 1 and the signal receiving module (the signal processing unit 2), and the first main control MCU dynamically adjusts the switching current (the dynamic characteristic current signals) through the dynamic load control circuit according to the number (zero pulse signal quantity) of the zero pulse signals on the power grid detected by the signal receiving module. The liquid crystal display circuit and the buzzer circuit form a man-machine interaction unit for displaying or prompting communication state, phase information, fault information and the like.
The power supply circuit of the present embodiment is composed of a strong current filter circuit and a switching power supply circuit. The strong current filter circuit is connected with a zero line and a live line in a power grid line, the strong current filter circuit and the switching power supply circuit of the embodiment both adopt a conventional strong current filter circuit and a conventional switching power supply circuit, and specific circuit diagrams are respectively shown in fig. 3 and 4. The strong current filter circuit can meet the requirements of short-circuit protection, overcurrent protection, impact resistance, IEC 60335 (the time of power failure meets the critical voltage 34V and is less than 1 second) and EMC/EMI, and simultaneously ensures that the characteristic current signal is not interfered by high-frequency pulses generated by the switching power supply circuit, so that the waveform of the characteristic current signal is not distorted, and the signal-to-noise ratio is improved.
Fig. 5, fig. 6, fig. 7 and fig. 8 are circuit diagrams of the first main control MCU and its peripheral circuit, the communication circuit, the buzzer circuit and the liquid crystal display circuit, respectively, according to this embodiment. The communication circuit of this embodiment adopts LORA communication module, and LORA communication module and first master control MCU's signal pin links to each other to interact with first master control MCU, first master control MCU still links to each other with liquid crystal display circuit and bee calling organ circuit respectively through its signal pin, thereby control liquid crystal display circuit and bee calling organ circuit's operating condition.
Fig. 9 is a circuit diagram of the load switching circuit according to this embodiment, and as shown in fig. 9, the load switching circuit includes a high-pass filter circuit, a gate driver, a weak current protection circuit, an Insulated Gate Bipolar Transistor (IGBT), a load resistor, and a full-wave rectification circuit. The high-frequency PWM signal generated by the first main control MCU is output to the high-pass filter circuit for filtering, then sequentially passes through the gate driver and the weak current protection circuit to drive the IGBT, and then generates a high-frequency characteristic current signal through the full-wave rectification circuit and the load resistor and outputs the high-frequency characteristic current signal to the low-voltage power grid.
The high-pass filter circuit of this embodiment is composed of a first capacitor C2 and a first resistor R720, one end of the first capacitor C2 is connected to the output pin of the first main control MCU, and the other end is grounded via the first resistor R720 and is simultaneously connected to the input pin of the gate driver IC 12. The model of the gate driver IC2 of this embodiment is IR4427, pin 1, pin 4, pin 5 and pin 8 of the gate driver IC2 are blank pins, pin 2 is an input pin, pin 2 is connected to the output terminal of the high-pass filter circuit, pin 3 is grounded, pin 6 is a voltage input pin, pin 6 of this embodiment is connected to the +15V power supply terminal, pin 6 is grounded via the second capacitor C724 and the third capacitor C723, pin 7 is a signal output pin, and is connected to the input terminal of the weak current protection circuit.
The weak current protection circuit of this embodiment includes a second resistor R737, a third resistor R738, a fourth resistor R739, a fifth resistor R740, a sixth resistor R741, a first diode D707, and a zener diode D706. One end of the fourth resistor R739, which is connected in parallel with the fifth resistor R740, is connected to the output pin of the gate driver IC12, the other end is connected to the cathode of the first diode D707, and the anode of the first diode D707 is connected to the gate of the igbt Q702. One end of the second resistor R737 and the third resistor R738 which are connected in parallel is connected to the output pin of the gate driver IC12, and the other end is connected to the gate of the igbt Q702. The second resistor R737, the third resistor R738, the fourth resistor R739, the fifth resistor R740, and the first diode D707 are mainly used to eliminate gate oscillation and power loss of the transfer driver. The cathode of the zener diode D706 is connected to the gate of the igbt Q702, and the anode is connected to the emitter of the igbt Q702. The sixth resistor R741 is a bleeder resistor, and has one end connected to the gate of the igbt Q702 and the other end connected to the emitter of the igbt Q702. The emitter of the insulated gate bipolar transistor Q702 is grounded. The collector of the insulated gate bipolar transistor Q702 is connected to the load resistor, and the insulated gate bipolar transistor Q702 is used to realize the fast on/off of the load resistor, so as to generate a high-frequency current signal.
The load resistor of the embodiment comprises four groups of resistors (R14, R17, R18, R19, R23, R24, R25 and R26) which are connected in series two by two and then connected in parallel, one end of the load resistor is connected with the collector of the insulated gate bipolar transistor Q702, the other end of the load resistor is connected with one alternating current input end of the full-wave rectifying circuit, the other alternating current input end of the full-wave rectifying circuit is grounded, and the direct current output end of the full-wave rectifying circuit is connected with the live wire and the zero wire of a low-voltage power grid. The full-wave rectification circuit of the present embodiment is a rectification bridge composed of 4 diodes (D1, D2, D5, D6).
The load switching circuit of the embodiment directly short-circuits a cold Ground (GND) and a hot ground (AGND) to generate a current pulse signal, and meanwhile, an IGBT is used as a switching device, the frequency of the generated current pulse signal can reach 1MHz theoretically, the higher the frequency of the signal is, the better the transmission characteristic on a power grid is, the influence of a switching power supply can be effectively avoided, and the pollution to the power grid is reduced while the requirement of sending characteristic signals is met.
Fig. 10 is a circuit diagram of the dynamic load control circuit in this embodiment, and as shown in fig. 10, the dynamic load control circuit includes at least one control branch circuit composed of a triode and a solid-state relay, where the control branch circuit is used to control a load resistor to access a load switching circuit, so as to adjust the switching current. The dynamic load control circuit of the embodiment comprises two control branches, wherein one end of each control branch is connected with a first main control MCU, the other end of each control branch is connected with a load switching circuit and connected between a load resistor and a full-wave rectification circuit of the load switching circuit, the control branches drive solid-state relays (IC1 and IC6) through triodes (Q1 and Q30) to further control high-power load resistors to be connected into the load switching circuit, and switching signals (1 and 0) of two groups of control circuits can realize the current regulation of 00, 01, 10 and 11 in four gears.
As shown in fig. 11, the signal receiving module of the present embodiment includes a power supply unit, a signal acquisition unit 2, and a signal processing unit 3, wherein the power supply unit supplies power to the signal acquisition unit 2 and the signal processing unit 3. The signal acquisition unit 2 comprises a plurality of signal acquisition channels, each signal acquisition channel corresponds to one phase line (A/B/C phase) in the power grid system, and each signal acquisition channel comprises a TMR sensor, an instrument amplification circuit, a high-pass filter circuit and a first band-pass filter circuit which are sequentially connected. The TMR sensor is responsible for collecting weak magnetic field change information caused by characteristic current signals on a power grid line, the mixed micro signals are output to the instrument amplification circuit in a differential mode, the instrument amplification circuit amplifies the micro signals output by the TMR sensor and outputs the amplified signals to the high-pass filter, and the high-pass filter circuit filters 50HZ power frequency signals in the signals and outputs the filtered signals to the first band-pass filter circuit. Fig. 12 and 13 are circuit diagrams of a meter amplifying circuit and a first band-pass filter circuit of the present embodiment, respectively, and both the meter amplifying circuit and the first band-pass filter circuit of the present embodiment are conventional meter amplifying circuits and band-pass filter circuits. The TMR sensing technology is adopted for signal acquisition, non-contact magnetic field sensing is carried out at a receiving end (namely a power distribution room), and a rear end signal processing circuit is matched, so that a characteristic pulse current signal sent by a sending end can be effectively extracted, and the electric shock risk of power grid operation and maintenance personnel is effectively avoided.
The signal processing unit 3 comprises a signal processing channel corresponding to the signal acquisition channel, a second main control MCU and a second communication circuit, in a preferred embodiment, the signal processing unit 3 can further comprise an electric quantity display circuit and a buzzer circuit, and the second communication circuit and the buzzer circuit of the signal processing unit are the same as the first communication circuit and the buzzer circuit of the signal sending module. Each signal processing channel comprises a second band-pass filter circuit, a linear amplifying circuit and a signal shaping circuit which are sequentially connected, and the first band-pass filter circuit and the second band-pass filter circuit form a high-order band-pass filter, so that a better filtering effect can be obtained. The linear amplifying circuit is used for adjusting the input amplitude to be input to the signal shaping circuit, and the signal shaping circuit is used for converting irregular signal waveforms into pulse square waves with regular bit positions and then outputting the pulse square waves to the second main control MCU for processing. The second band-pass filter circuit and the linear amplifier circuit of this embodiment are both conventional band-pass filter circuits and linear amplifier circuits, and specific circuits are shown in fig. 14 and 15. The signal shaping circuit converts the characteristic current signal of the constant-frequency cutting power frequency sine wave which is acquired by the acquisition end and is subjected to filtering and amplification into a square wave signal. As shown in fig. 16, the signal shaping circuit employs a voltage comparator, a threshold (i.e., a reference level) is set at an inverting input terminal of the voltage comparator, and the voltage comparator outputs a square wave pulse signal when a characteristic current signal is input at a non-inverting input terminal of the voltage comparator.
When the platform area recognition instrument is used for platform area recognition, after the platform area recognition instrument is electrified, a signal acquisition unit at a receiving end acquires magnetic field information of current on a power grid line and sends the magnetic field information to a signal processing unit so as to determine zero pulse signal quantity of the current platform area power grid line; then, a signal sending module of a sending end determines the level of switching current according to the zero pulse semaphore and starts to carry out load switching; after the load is switched, the signal acquisition unit at the receiving end acquires the magnetic field information of the current on the power grid line again to determine the mixed pulse semaphore (the mixed pulse semaphore is the characteristic current semaphore generated by the switched load + the zero pulse semaphore) of the power grid line of the current transformer area, and calculates the difference between the mixed pulse semaphore and the zero pulse semaphore to perform the determination of transformer area attribution and the determination of phase attribution. The calculation of the current from the magnetic field information detected by the magnetic field sensor and the calculation of the pulse semaphore from the current information are conventional methods and are not innovative in the present invention, and the master MCU can perform the calculation by a known algorithm program, which is not described herein in detail.
Harmonic components on a power grid generally change irregularly, and harmonic components of each transformer area are different, so that the dynamic current pulse can effectively make up the defects, transformer area attribution and phase identification can be quickly and accurately made, timely dynamic current regulation can adapt to more transformer areas, and the signal-to-noise ratio is improved on data sample collection. The invention obtains the current information on the power grid line by a magnetic field detection mode, can sensitively detect the small current signal, and according to the Biot-Saval law, the magnitude of the magnetic induction intensity dB generated by the current element Idl at a certain point P in the space is in direct proportion to the magnitude of the current element Idl, after the magnitude level of the switching current is reduced, the magnetic induction intensity can be reduced, the electromagnetic radiation is reduced, the phenomenon of 'serial phase' is effectively solved, and the phenomenon that the data cannot be identified (namely the data has no obvious difference) and even the phase misjudgment caused by 'serial phase' is avoided.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.