CN213181987U - Secondary circuit wiring calibration system of electric energy metering device - Google Patents
Secondary circuit wiring calibration system of electric energy metering device Download PDFInfo
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- CN213181987U CN213181987U CN202021102462.1U CN202021102462U CN213181987U CN 213181987 U CN213181987 U CN 213181987U CN 202021102462 U CN202021102462 U CN 202021102462U CN 213181987 U CN213181987 U CN 213181987U
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Abstract
The utility model discloses a secondary circuit wiring calibration system of an electric energy metering device, which comprises a shell, a sine wave signal generating circuit, a signal sampling circuit, a man-machine interaction circuit and a main control circuit, wherein the sine wave signal generating circuit, the signal sampling circuit, the man-machine interaction circuit and the main control circuit are arranged in the shell; the sine wave signal generating circuit comprises a digital-to-analog conversion circuit and a power amplifying circuit, and the signal sampling circuit comprises a signal conditioning circuit and a sampling circuit; the main control circuit is respectively connected with the digital-analog conversion circuit, the signal conditioning circuit and the human-computer interaction circuit, the digital-analog conversion circuit is further connected with the power amplification circuit, two output ends of the power amplification circuit are respectively connected with two ends of the secondary side of the mutual inductor of the electric energy metering device, the signal conditioning circuit is further connected with the sampling circuit, and the sampling circuit is connected with two output ends of the power amplification circuit. Adopt the utility model discloses, need not to adorn meter personnel and get into load current and gather voltage signal in the electric energy measurement cabinet, and have higher detection precision.
Description
Technical Field
The utility model relates to a circuit check out test set especially relates to an electric energy metering device secondary circuit wiring check-up system.
Background
In the meter installation and power connection link in the test and reception of the 10kV electric energy metering device, meter installation and power connection personnel must confirm whether the secondary side wires of the voltage transformer and the current transformer are correctly laid out before installing the meter, otherwise, the wiring is found to be wrong after the meter installation, and the wiring is inconvenient to change. In the actual acceptance work, the wiring from the secondary side of the mutual inductor to the test junction box is already tied, and the direct wiring is inconvenient.
Therefore, the secondary connection of the mutual inductor is generally checked by using a direct current method, namely, one meter assembling person loads direct current voltage on the primary side of the mutual inductor by using a battery to generate transient current, and simultaneously, the other meter assembling person contacts the tail ends of secondary side lines of the current mutual inductor by using two meter pens of the universal meter which is used for striking a voltage level, and whether the connection is reversely connected is judged by observing the swinging of a pointer in the meter.
Because of the limitation of the installation structure of the mutual inductor of the electric energy metering cabinet, meter installation personnel are inconvenient to drill the electric energy metering cabinet and even have the danger of being shocked by electricity when the secondary side of the current mutual inductor is in an open circuit state. In addition, when the transformation ratio of the current transformer is large, the swinging of the multimeter pointer is very weak when the method is used for testing, and the polarity is difficult to judge.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem that a secondary circuit wiring calibration system of electric energy metering device is provided, need not to adorn table personnel and get into load current and gather voltage signal in the electric energy metering cabinet, and have higher detection precision.
In order to solve the technical problem, the utility model provides an electric energy metering device secondary circuit wiring calibration system, which comprises a shell, a sine wave signal generating circuit, a signal sampling circuit, a man-machine interaction circuit and a main control circuit, wherein the sine wave signal generating circuit, the signal sampling circuit, the man-machine interaction circuit and the main control circuit are arranged in the shell; the sine wave signal generating circuit comprises a digital-to-analog conversion circuit and a power amplifying circuit, and the signal sampling circuit comprises a signal conditioning circuit and a sampling circuit; the main control circuit is respectively connected with the digital-analog conversion circuit, the signal conditioning circuit and the human-computer interaction circuit, the digital-analog conversion circuit is further connected with the power amplification circuit, two output ends of the power amplification circuit are respectively connected with two ends of the secondary side of the mutual inductor of the electric energy metering device, the signal conditioning circuit is further connected with the sampling circuit, and the sampling circuit is connected with two output ends of the power amplification circuit.
As an improvement of the scheme, the signal conditioning circuit comprises a blocking capacitor, a voltage follower, a high-precision power resistor, an instrument amplifier and a conditioning digital-to-analog conversion circuit which are sequentially connected, the conditioning digital-to-analog conversion circuit is connected with the main control circuit, and the blocking capacitor is connected with two output ends of the power amplification circuit.
As an improvement of the above scheme, the human-computer interaction circuit comprises an LCD circuit.
As an improvement of the scheme, the human-computer interaction circuit further comprises a display instrument and a key, and the display instrument and the key are connected with the LCD circuit.
As an improvement of the scheme, the device also comprises a power supply source which is arranged in the shell and is connected with the main control circuit.
As an improvement of the above, the power amplifying circuit includes a protection circuit.
As a modification of the above, the main control circuit includes a timer circuit.
As an improvement of the scheme, the shell is provided with a grounding point, and the grounding point is connected with the grounding wire.
Implement the utility model has the advantages that:
implement the utility model discloses electric energy metering device secondary circuit wiring calibration system need not to adorn table personnel and gets into load current and gather voltage signal in the electric energy metering cabinet, and has higher detection precision.
Specifically, the function of the sine wave signal generating circuit is to generate a sine wave voltage signal, and the function of the signal sampling circuit is to collect a voltage signal of a secondary side line of the transformer. The main control circuit is respectively connected with the two circuits, so that sine wave voltage signals can be loaded to the secondary side of the mutual inductor according to control signals of the main control circuit, voltage signals at two ends of the secondary side of the mutual inductor are collected, after the voltage signals are collected, the main control circuit can judge whether lines of the secondary side of the mutual inductor are reversely connected according to the voltage signals at the two ends, and meter installation personnel perform manual detection.
The sine wave signal generating circuit comprises a digital-to-analog conversion circuit and a power amplifying circuit, wherein the power amplifying circuit amplifies the sine wave signal so as to improve the load carrying capacity of the secondary side of the mutual inductor. The digital-to-analog conversion circuit is used for converting the analog signals into digital signals, and the digital signals of the main control circuit are conveniently converted into sine wave voltage signals to be output.
The signal sampling circuit comprises a signal conditioning circuit and a sampling circuit, the sampling circuit transmits voltage signals at two ends of the secondary side of the acquired transformer to the signal conditioning circuit, the signal conditioning circuit performs signal amplification and other processing on the signals to improve detection precision when the transformation ratio of the current transformer is large, the processed voltage signals are transmitted to the main control circuit, and the main control circuit performs verification processing on the voltage signals.
Drawings
Fig. 1 is a schematic diagram of the overall structure of the secondary circuit wiring calibration system of the electric energy metering device of the present invention;
fig. 2 is a schematic structural diagram of a signal sampling circuit of the secondary circuit wiring calibration system of the electric energy metering device of the present invention;
FIG. 3 is a circuit diagram of a chip of the AD5453 type of the secondary circuit wiring checking system of the electric energy metering device of the present invention;
FIG. 4 is a circuit diagram of an OPA551 type chip of the electric energy metering device secondary circuit wiring verification system of the present invention;
FIG. 5 is a circuit diagram of the AD 7606-4A/D conversion chip of the secondary circuit wiring calibration system of the electric energy metering device of the present invention;
FIG. 6 is a typical design wiring diagram of the 10kV electric energy metering device of the secondary circuit wiring calibration system of the electric energy metering device of the present invention;
fig. 7 is a positive wiring diagram of the secondary side of the mutual inductor of the secondary circuit wiring calibration system of the electric energy metering device of the present invention;
fig. 8 is a secondary side reversed polarity wiring diagram of the mutual inductor of the secondary circuit wiring calibration system of the electric energy metering device of the utility model;
fig. 9 is a conventional detection circuit diagram of the secondary circuit wiring calibration system of the electric energy metering device of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings. Only this statement, the utility model discloses the upper and lower, left and right, preceding, back, inside and outside etc. position words that appear or will appear in the text only use the utility model discloses an attached drawing is the benchmark, and it is not right the utility model discloses a concrete restriction.
Fig. 1 is the general structure schematic diagram of the secondary circuit wiring calibration system of the electric energy metering device of the present invention. Fig. 2 is the structure schematic diagram of the signal sampling circuit of the secondary circuit wiring calibration system of the electric energy metering device of the utility model. The utility model discloses a secondary circuit wiring calibration system of an electric energy metering device comprises a shell 1, a sine wave signal generating circuit, a signal sampling circuit 3, a man-machine interaction circuit 4 and a main control circuit 5, wherein the sine wave signal generating circuit, the signal sampling circuit, the man-machine interaction circuit and the main control circuit are arranged in the shell; the sine wave signal generating circuit comprises a digital-to-analog conversion circuit 21 and a power amplifying circuit 22, and the signal sampling circuit 3 comprises a signal conditioning circuit 31 and a sampling circuit 32; the main control circuit 5 is respectively connected with the digital-to-analog conversion circuit 21, the signal conditioning circuit 31 and the human-computer interaction circuit 4, the digital-to-analog conversion circuit 21 is further connected with the power amplification circuit 22, two output ends a and b of the power amplification circuit 22 are respectively connected with two ends of the secondary side of the mutual inductor of the electric energy metering device, the signal conditioning circuit 31 is further connected with the sampling circuit 32, and the sampling circuit 32 is connected with two output ends a and b of the power amplification circuit 22.
In fig. 1, two sampling circuits 32 are connected to two output terminals a, b of the power amplifier circuit 22, respectively. The sampling circuit is connected with the output end a and used for collecting voltage signals of the output end a, and the sampling circuit is connected with the output end b and used for collecting voltage signals of the output end b.
Implement the utility model discloses electric energy metering device secondary circuit wiring calibration system need not to adorn table personnel and gets into load current and gather voltage signal in the electric energy metering cabinet, and has higher detection precision.
Specifically, the function of the sine wave signal generating circuit 2 is to generate a sine wave voltage signal, and the function of the signal sampling circuit 3 is to collect a voltage signal of a secondary side line of the transformer. The main control circuit 5 is respectively connected with the two circuits, so that sine wave voltage signals can be loaded to the secondary side of the transformer according to control signals of the main control circuit 5, voltage signals at two ends of the secondary side of the transformer are collected, after the voltage signals are collected, the main control circuit 5 can judge whether lines of the secondary side of the transformer are reversely connected according to the voltage signals at the two ends, and meter installation personnel carry out manual detection.
The sine wave signal generating circuit 3 comprises a digital-to-analog conversion circuit 21 and a power amplifying circuit 22, wherein the power amplifying circuit 22 amplifies the sine wave signal to improve the loading capacity of the secondary side of the transformer. The digital-to-analog conversion circuit 21 is used for converting digital signals and analog signals into each other, and is convenient for converting the digital signals of the main control circuit into sine wave voltage signals for output.
The signal sampling circuit 3 comprises a signal conditioning circuit 31 and a sampling circuit 32, the sampling circuit 32 transmits the collected voltage signals at two ends of the secondary side of the transformer to the signal conditioning circuit, the signal conditioning circuit 31 amplifies the signals and the like to improve the detection precision when the transformation ratio of the current transformer is large, the processed voltage signals are transmitted to the main control circuit 5, and the main control circuit 5 performs data operation, verification and the like on the voltage signals.
Additionally, the utility model discloses electric energy metering device secondary circuit wiring check-up system response is rapid when the test, and the output voltage is low, and the wiring is simple, and is safe guaranteed, and product application scope is wide, can use under multiple environment such as electricity generation, transmission of electricity, transformer, distribution, low cost moreover.
The digital-to-analog conversion circuit 21 may be a chip of an AD5453 type.
Fig. 3 is a circuit diagram of a chip of an AD5453 model, the precision of which is 14 bits, the setup time is only 1.5 microseconds, parallel bus input and dual power output are supported, and the related functional requirements of the utility model are satisfied.
The power amplifier circuit 22 may be a chip of type OPA551 by TI.
Fig. 4 is a circuit diagram of an OPA551 model chip. The chip of the type can continuously output 5A large current, the peak current can reach 10A, and the chip is internally provided with a protection circuit.
The signal conditioning circuit 31 includes a blocking capacitor 311, a voltage follower 312, a high-precision power resistor 313, an instrument amplifier 314, and a conditioning digital-to-analog conversion circuit 315, which are connected in sequence. The conditioning digital-to-analog conversion circuit 315 is connected to the main control circuit, and the blocking capacitor 311 is connected to the two output terminals a, b of the power amplification circuit 22.
After passing through the blocking capacitor 311, the current signals at the two output terminals a, b pass through the voltage follower 312 which is composed of an operational amplifier and can further provide the loading capacity, and finally are converted into voltage signals through the high-precision power resistor 313, and then are amplified and transmitted to the conditioning digital-to-analog conversion circuit 315 through the instrument amplifier 314.
The operational amplifier can adopt a TL062 signal circuit.
The conditioning digital-to-analog conversion circuit can adopt an AD7606-4 analog-to-digital conversion chip of ADI company.
FIG. 5 is a circuit diagram of an AD7606-4 analog-to-digital conversion chip, which is powered by a single power supply 5V and supports bipolar signal sampling of +/-5V or +/-10V. This may greatly simplify the design of the power supply. While it supports 4-channel simultaneous sampling, each channel can sample at a rate up to 200 KSPS.
The human-computer interaction circuit 4 comprises an LCD circuit 41.
The human-computer interaction circuit 4 further comprises a display 42 and a key 43, and the display 42 and the key 43 are connected with the LCD circuit 41.
The man-machine interaction circuit 4 can adopt a crystal union communication type 128128G-338-BN monochrome liquid crystal, the product is provided with a word stock, the operation instruction is simplified, the interface mode is flexible, and the development cost is saved. And simultaneously, four independent keys are used for inputting so as to meet the requirements of testing, data checking and the like. The meter installing personnel test through the keys and can check the test result of the display instrument.
The utility model discloses electric energy metering device secondary circuit wiring check-up system still includes power supply 6, and power supply 6 installs in shell 1 to be connected with main control circuit 5.
The power supply can adopt a lithium battery with the specification of 12V and 1800mA, the weight of the whole equipment is reduced, the lithium battery is connected with a main control circuit, and the main control circuit can convert the voltage of the lithium battery into the voltage type grade required by the test.
The power amplification circuit includes a protection circuit.
The protection circuit is used for protecting the power amplification circuit from being damaged due to voltage transient.
The main control circuit includes a timer circuit.
The timer circuit is used for controlling the generation frequency and the time of the sine wave signal and controlling the sampling frequency and the sampling time.
Preferably, the main control circuit may adopt a chip of a DSP2812 model, which integrates an EVA timer of a time manager, and may implement the functions of sine wave signal generation, frequency control of signal sampling, and the like.
The housing 1 is provided with a grounding point 11, and the grounding point 11 is connected with a grounding wire.
After the grounding point is connected with the ground wire, if the circuit arranged in the shell generates electric leakage, the current can be effectively led to the ground from the shell, and the meter installing personnel is prevented from electric shock.
The following explains the principle of the test.
FIG. 6 is a wiring diagram of a typical design of a 10kV electric energy metering device. A, B, C is a three-phase busbar, A410 and A411 are secondary outgoing lines of the phase-A current transformer, C410 and C411 are secondary outgoing lines of the phase-C current transformer, and A630, B630 and C630 are three-phase outgoing lines of a secondary side A, B, C of the transformer. The ends of the current transformer sides A411 and C411 are grounded, and the end of the voltage transformer B630 is grounded. Generally, the secondary lines A410, A411, C410, C411, A630, B630 and C630 are arranged along the trunking from the secondary terminal of the transformer to the front of the electric energy meter in the instrument room through the transformer room. In actual wiring, A, B, C three phases are yellow-green-red, because a410 and a411 and C410 and C411 are the same color, wrong connection is easy to occur at the front end of the electric energy meter to cause reverse polarity, and because the voltage transformers are connected in a V/V mode, wrong connection occurs at a630 and a B630, and a B630 and a C630 at a certain probability.
As can be seen from fig. 6, the terminals a411, C411, and B630 on the secondary side of the transformer are grounded. Under the condition that the primary side of the transformer is not electrified, if a grounded wire end can be detected on the secondary side of the transformer, the wiring correctness can be effectively verified.
However, the direct current resistance of the current transformer and the voltage transformer is very small, and is in the milliohm level, and the secondary side impedance is also a very small value under the power frequency condition. Because the resistance value is too small, it is not easy to judge that the end is the grounding point by directly measuring the resistance of the a ', b' point and the grounding point by using the ohmic contact of the multimeter.
Fig. 7 and 8 are wiring diagrams of positive polarity connection and reverse polarity connection of the secondary side of the transformer, respectively. In order to reliably judge the grounding point, a high-frequency sine wave is conducted on the secondary winding side of the mutual inductor, the potentials between the a 'and b' points of the side and the grounding point are detected in real time, the point potential connected with the grounding point is always in a low potential, and the non-grounding point has sine wave output with certain frequency and amplitude. Thus, it can be determined that the terminal is grounded.
Fig. 9 is a conventional detection circuit diagram. Neglecting the direct current resistance of the transformer, under the condition that the secondary side of the transformer is open-circuited, the potentials of a 'and b' are simply calculated to obtain the following expression:
UB＝0 (1)
wherein, UAVoltage signal detected for point a', UBThe voltage signal detected for the point b', f is the frequency of the sine wave signal, L is the length of the transformer, R is the resistance of the sampling resistor of the series circuit, U is the output voltage of the power supply generating the high frequency alternating sine wave signal, and I is the current passing through the transformer.
As shown in the formula (2), for better judgment of polarity, the larger the frequency and amplitude of the sine wave signal outputted from the power supply, the better the obtained UAThe amplitude is close to the input voltage of the power supply, so that the signal is easier to detect, but the input frequency is not too high in the actual process, and the amplitude is not too large. When the secondary side of the transformer is open-circuited, a voltage with a transformation ratio of k times can be induced on the primary side of the transformer, so that potential safety hazards are generated. Similarly, the frequency is too high, the divided voltage of the sampling resistor is very small, and the misjudgment of the open circuit state of the circuit is easily caused. In practical application, the value should be reasonably taken according to the practical mutual inductor.
The criterion of the wiring state of the secondary circuit of the mutual inductor is shown in the table 1:
| measured quantity | State of connection |
| I>0，UA＝U，UB＝0 | Positive polarity |
| I>0，UA＝0，UB＝U | Reversed polarity |
| I>0，UA＝0，UB＝0 | Short circuit |
| I＝0，UA＝0，UB＝0 | Open circuit |
TABLE 1
The following is the utility model discloses electric energy metering device secondary circuit wiring calibration system's operation process explains, and the operation process can divide into initialization, production sine wave signal, signal sampling, data operation and human-computer interaction.
First, the main control circuit 5 initializes control parameters, and then the meter loader inputs a control signal for starting verification through the key 43, and the LCD circuit 41 transmits the control signal to the main control circuit 5.
Then, the main control circuit 5 drives the digital-to-analog conversion circuit 21 to generate a sine wave signal, generally, an array obtained by sampling the sine wave at regular intervals in sequence is set in the digital-to-analog conversion circuit 21 as a sine wave table, and then the digital-to-analog conversion circuit 21 generates the sine wave signal by using a table look-up method. According to a data manual of an AD5453 chip adopted by the digital-to-analog conversion circuit 21, a 128-bit sine wave table function for outputting positive and negative voltages is prepared as follows:
Y＝ceil((214/2-1)*sin(0:π·2/128:2·π)+213)
wherein ceil denotes an integer function. Sine waves with different frequencies can be obtained by outputting the sine wave table at different equal intervals through the digital-to-analog conversion circuit 21. For a sine wave table with a specific fixed length, the shorter the equal interval time, the higher the output frequency. Then the sine wave signal can be obtained by using the timer circuit of the main control circuit to time and output the signals in turn through the digital-to-analog conversion circuit. The sine wave signal is amplified by the power amplifying circuit 22 and then output to the secondary side of the transformer through the output terminals a, b of the power amplifying circuit.
Then the signal sampling circuit 3 samples the signal, because the sine wave signal is sampled, the amplitude and the frequency of the sine wave signal need to be obtained, and according to the shannon sampling theorem, the sampling frequency must be more than twice of the sampled frequency. In order to realize the accuracy and rapidness of the judgment, the number of sampling points is 128, and the sampling frequency of an AD7606-4 type chip adopted by the conditioning digital-to-analog conversion circuit 315 is set to be 30 Khz. The sampling frequency of the AD7606-4 model chip is also controlled by a time manager EVA timer integrated with the DSP2812 model chip adopted by the main control circuit 5. The AD7606-4 type chip adopts a serial SPI communication mode for communication, so that fewer signal lines are needed for communication, and only two isolation chips are needed.
And finally, the main control circuit 5 performs data operation processing on the sampling signals, wherein a Fast Fourier Transform (FFT) algorithm is mainly used. The fast fourier transform algorithm is an efficient algorithm for fourier transform. Therefore, the sampled time domain signal can be converted into a frequency domain signal, and the frequency and the amplitude of the fundamental wave of the sampled sine wave can be obtained. The grounding condition of the secondary side mutual inductor can be judged through the parameter of the fundamental wave of the sampled signal, so that the polarity and other wiring states of the mutual inductor are further judged.
In addition, during the operation process, the man-machine interaction circuit 4 displays the data processing result on the display instrument 42 in real time.
The foregoing is a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations are also considered as the protection scope of the present invention.
Claims (8)
1. A secondary circuit wiring calibration system of an electric energy metering device is characterized by comprising a shell, a sine wave signal generating circuit, a signal sampling circuit, a man-machine interaction circuit and a main control circuit, wherein the sine wave signal generating circuit, the signal sampling circuit, the man-machine interaction circuit and the main control circuit are arranged in the shell;
the sine wave signal generating circuit comprises a digital-to-analog conversion circuit and a power amplifying circuit, and the signal sampling circuit comprises a signal conditioning circuit and a sampling circuit;
the main control circuit is respectively connected with the digital-analog conversion circuit, the signal conditioning circuit and the human-computer interaction circuit, the digital-analog conversion circuit is further connected with the power amplification circuit, two output ends of the power amplification circuit are respectively connected with two ends of a secondary side of a mutual inductor of the electric energy metering device, the signal conditioning circuit is further connected with the sampling circuit, and the sampling circuit is connected with two output ends of the power amplification circuit.
2. The secondary circuit wiring verification system of the electric energy metering device as claimed in claim 1, wherein the signal conditioning circuit comprises a blocking capacitor, a voltage follower, a high-precision power resistor, an instrument amplifier and a conditioning digital-to-analog conversion circuit which are connected in sequence, the conditioning digital-to-analog conversion circuit is connected with the main control circuit, and the blocking capacitor is connected with two output ends of the power amplification circuit.
3. The secondary circuit wiring verification system of the electric energy metering device as claimed in claim 1, wherein the human-computer interaction circuit comprises an LCD circuit.
4. The secondary circuit wiring verification system of the electric energy metering device as claimed in claim 3, wherein the human-computer interaction circuit further comprises a display instrument and a key, and the display instrument and the key are connected with the LCD circuit.
5. The secondary circuit wiring verification system of the electric energy metering device as claimed in claim 1, further comprising a power supply source installed in the housing and connected to the main control circuit.
6. The secondary circuit wiring verification system of the electric energy metering device as claimed in claim 1, wherein the power amplification circuit includes a protection circuit.
7. The secondary circuit wiring verification system of an electric energy metering device according to claim 1, wherein said main control circuit includes a timer circuit.
8. The secondary circuit wiring verification system of an electric energy metering device according to claim 1, wherein said housing is provided with a grounding point, and said grounding point is connected to a grounding line.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202021102462.1U CN213181987U (en) | 2020-06-15 | 2020-06-15 | Secondary circuit wiring calibration system of electric energy metering device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021102462.1U CN213181987U (en) | 2020-06-15 | 2020-06-15 | Secondary circuit wiring calibration system of electric energy metering device |
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| CN213181987U true CN213181987U (en) | 2021-05-11 |
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| CN202021102462.1U Active CN213181987U (en) | 2020-06-15 | 2020-06-15 | Secondary circuit wiring calibration system of electric energy metering device |
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