CN112595892A - Power grid harmonic detection device - Google Patents
Power grid harmonic detection device Download PDFInfo
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- CN112595892A CN112595892A CN202011550014.2A CN202011550014A CN112595892A CN 112595892 A CN112595892 A CN 112595892A CN 202011550014 A CN202011550014 A CN 202011550014A CN 112595892 A CN112595892 A CN 112595892A
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
The invention provides a power grid harmonic detection device, which comprises a Hall sensor, a storage, a communication module, a signal detection and conditioning circuit for signal processing, a phase-locked loop PLL circuit, an AD conversion circuit for signal acquisition, a phase voltage capturing and conditioning circuit for synchronous sampling, a high-precision processor for data processing, an LCD display circuit for observation and input and output equipment for man-machine interaction.
Description
Technical Field
The utility model provides a power grid harmonic detection device belongs to the detection device field, concretely relates to power grid harmonic detection device.
Background
When the power system normally operates, the power system supplies electric energy to users at rated voltage and rated frequency, but in actual operation, the load in the power grid is constantly changed, the load comprises various nonlinear power electronic devices such as inductance and capacitance, and particularly, electronic devices such as a switching power supply, a thyristor and the like widely adopted in the field of control of electrical equipment and electronic systems inevitably generate non-sinusoidal waveforms to cause disturbance to the power grid. In addition to these power electronic devices, the power supply system is loaded with non-linear loads such as arc furnace, frequency converter, rectifier, rotating electrical machine, etc. these loads, unlike pure resistance electric devices, consume a large amount of reactive power while consuming active power, which causes great disturbance to the power grid, and the waveform in the power supply network is distorted and is no longer a single sine wave waveform of rated frequency. The method is characterized in that a large number of current components with frequencies higher than the rated frequency are generated in a power grid, the components with frequencies higher than the rated frequency are called harmonic components, the generation of a large number of harmonics becomes one of important factors influencing the quality of electric energy in the current power system, and the harm of the power harmonics to the power system is mainly shown in the following aspects:
(1) effects of harmonics on the line
(2) Influence on power transformers
(3) Influence on Power capacitors
(4) Influence on Power capacitors
(5) Influence on the electric machine
(6) Effects on relay protection and automation
(7) Interference to communication line
The sampling mode adopted in various monitoring instruments of the current power system is generally as follows: the mode of 'multi-way switch + sampling hold + A/D conversion' has simple hardware design and low cost, and can obtain good results in a system with low requirement on synchronism, but if the mode is adopted in harmonic analysis, even under the condition that 128 points are sampled per cycle, the phase of 19 times of harmonic can bring 6-degree errors at least, the errors can be ignored for a system which extracts fundamental wave components for signal analysis, and the measurement of higher harmonics can make the measured data have no credibility.
The electric power harmonic detection device appears at home and abroad, the electric power harmonic detection device at home and abroad has advanced performance, wide application range, durability and reliability, but the price is expensive, and the defects of different degrees exist in the aspects of measurement function, measurement channel and data uniformity and the like, the price of domestic products is low, but the manufacturing process is poor, the reliability and precision are generally not high, most of the products cannot be portable, the device is mainly suitable for harmonic measurement, and the gap is larger compared with foreign products in the aspects of analysis of higher harmonics, waveform analysis, selection of sampling windows, data processing and result output.
Disclosure of Invention
In order to solve the problems, the invention provides the power harmonic detection device which is high in measurement accuracy, can measure and process electric energy signals in real time and is convenient to carry, has the advantages of enriching the functions of the harmonic detection device, particularly the synchronous sampling and data storage or transmission functions, improving the accuracy, obtaining the original power grid data and further analyzing the power grid quality. The invention discloses a power grid harmonic detection device, which is realized by the following technical scheme:
a power grid harmonic detection device comprises a voltage Hall sensor for detecting a voltage signal, a current Hall sensor for detecting a current signal, a storage and a communication module, a signal detection and conditioning circuit for sampling signal processing, a phase voltage capturing and conditioning circuit for synchronous sampling, a phase-locked loop PLL circuit, an AD conversion circuit for acquiring signals, a high-precision processor for data processing, input and output equipment for man-machine interaction and an LCD display circuit for a display part;
furthermore, the signal detection and conditioning circuit comprises a low-pass filtering circuit, a voltage amplifying circuit and an output clamping circuit which are sequentially connected, wherein the input end of the signal processing circuit is used for receiving the acquired voltage and current signals, and is connected with the input end of the AD conversion circuit after being filtered;
the phase voltage capturing and conditioning circuit for synchronous sampling comprises a voltage reduction circuit, a low-pass filter circuit, a phase shift circuit, a zero-crossing comparison circuit, a voltage amplification circuit and an optical coupling isolation circuit, wherein the phase voltage capturing circuit is used for connecting a phase voltage signal which is synchronously acquired to a phase-locked loop PLL circuit after voltage reduction, filtering, phase shift, zero-crossing comparison and amplification as a signal synchronous sampling mark;
furthermore, the phase-locked loop PLL circuit adopts a CD4046 chip to realize the phase-locked function;
furthermore, the AD conversion circuit for acquiring signals completes the function of acquiring and converting the power grid data with high precision;
further, the processor for data processing adopts a data processor, and comprises a data acquisition module for receiving acquired signals, an analysis module for processing the acquired signals, a compression module for storing data, a communication module for data transmission, a display module for displaying data, and a management module for setting authority.
As described above, the power grid harmonic detection device provided by the present invention has the following effects:
according to the power grid harmonic detection device, detection equipment meets the accuracy requirement of a national standard harmonic test instrument, the circuit design aspect meets the relevant standard of international electronic equipment, the requirements of low power consumption, low radiation and electromagnetic interference resistance are met, and the requirement on the use environment is low. The appearance is focused on the handheld equipment, the volume is ensured to be small as much as possible, and the handheld equipment is easy to carry. The equipment is provided with a protection device, so that the equipment can be prevented from being damaged due to external environment abnormity or manual misoperation; the hardware of the equipment has good expansibility, and functional devices can be conveniently added or removed according to requirements. And in the aspect of software, an excellent operating system and a component technology are adopted, and an application program interface is friendly and easy to operate.
Drawings
FIG. 1 is a hardware architecture diagram of the present invention;
FIG. 2 is a schematic diagram of a sensor circuit required by the present invention;
FIG. 3 is a schematic diagram of the desired signal detection and conditioning circuit of the present invention;
FIG. 4 is a schematic diagram of the phase voltage capture conditioning circuit required by the present invention;
FIG. 5 is a schematic diagram of a phase locked loop circuit required by the present invention;
FIG. 6 is a schematic diagram of the AD conversion and driving circuit required by the present invention;
FIG. 7 is a schematic diagram of an LCD driving circuit required by the present invention;
FIG. 8 is a schematic diagram of the SD card link required by the present invention;
fig. 9 is a schematic diagram of the communication interface required by the present invention.
Detailed Description
The present invention may be embodied or carried out in other specific forms without departing from the spirit or essential attributes thereof, and it is to be understood that all matter contained in the specification is to be interpreted as illustrative and not in a limiting sense. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
In the voltage Hall circuit in fig. 2, a Hall voltage sensor CHV-50P is adopted to realize the purpose of voltage sampling, a primary side is connected with a resistor Ru1 in series, current flowing into a 1-end is introduced, two capacitors are connected in parallel on an alternating current input side for suppressing common mode interference, according to input rated current 10mA and measured voltage 220V, Ru1 is selected to be 2.2k, output current is in direct proportion to primary side voltage, in order to convert the output current into voltage, a resistor Ru2 is connected in series on an output side of the voltage sensor, and the output voltage is U1Its rated output current is 50mA, theoretically U1Less than or equal to 0.5V. The current Hall circuit adopts a LA25-NP Hall sensor produced by Lyme company, a sampling resistor Rm is connected to a voltage output end, and a voltage U is generated at the voltage output end after the current flows through the Rm0Then the collection of current signals is completed, the output rated current is 25mA, Rm is 20 omega, and theoretically U is0≤0.5V。
The voltage signal collected by the sensor is connected to the AD conversion part via the conditioning circuit of fig. 3. The conditioning circuit is formed by sequentially cascading a low-pass filter, a voltage amplifying circuit and an output clamp, wherein the low-pass filter mainly plays a role in filtering signals, aiming at higher harmonic signals, R1 is a 10k resistor, C1 is a 0.01 mu F capacitor, and at the moment, the critical sampling frequency is
Higher than f0The high-order harmonic signals are filtered, and the voltage amplification part mainly comprises the following parts: voltage follower, amplifying circuit and proportional circuitThe output clamp circuit has the function of setting the upper limit and the lower limit of an output signal, and the range of the ADS1278 converter is-2.5V to +2.5V, so that the output signal must be limited between-2.5V to +2.5V, the damage of the AD converter is avoided, and a voltage clamp is used for protecting sensitive circuit devices.
Fig. 4 shows that the phase voltage capturing and conditioning circuit is composed of five links, namely a voltage reduction circuit, a low-pass filter circuit, a phase shift circuit, a zero-crossing comparison circuit, a voltage amplification circuit and a photo-coupler isolation circuit in sequence, and captured phase voltages are connected with a phase-locked loop circuit after passing through the circuits, so that the purpose of synchronous sampling is achieved.
Fig. 5 is a phase-locked loop circuit, and only rectangular waves obtained by a capture circuit are used, and after the circuit is powered on and driven, a large number of pulses may be contained, and a strict rectangular wave signal cannot be obtained, so that the starting time is inaccurate, the purpose of synchronous sampling is difficult to achieve, and the harmonic detection precision is reduced to a great extent. In order to accurately track the phase voltage signal of the power grid, a PLL circuit is added behind the capturing and conditioning circuit, and then the PLL circuit is connected with a central processor to be used as a synchronous sampling signal.
The collected and processed signals are transmitted to the AD conversion circuit of FIG. 6, the ADS1278 converts the analog quantity into the digital quantity after the signals pass through the driving circuit, and then the collected signals are transmitted to the Exynos 4412 central processor. Fig. 7, fig. 8 and fig. 9 are respectively connected with the processor as a display, storage and communication part, GM82 8285C is used as the drive of the LCD display panel, the SD card is connected with the SPI of the processor as the removable data storage, and the MAX3232 is used to complete the signal transmission and communication with the upper computer.
The foregoing descriptions of embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and their practical applications, to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is, therefore, to be understood that the invention is intended to cover all modifications and the like within the scope of the following claims.
Claims (6)
1. The utility model provides a power grid harmonic detection device, includes voltage hall sensor, current hall sensor, accumulator and the communication module that is used for detecting voltage signal, is used for detecting current signal, its characterized in that: the power grid harmonic detection device further comprises a signal detection and conditioning circuit for sampling signal processing, a phase voltage capturing and conditioning circuit for synchronous sampling, a phase-locked loop PLL circuit, an AD conversion circuit for signal acquisition, a high-precision processor for data processing, input and output equipment for man-machine interaction and an LCD display circuit for a display part.
2. The grid harmonic detection device of claim 1, wherein: the signal detection and conditioning circuit comprises a low-pass filtering circuit, a voltage amplifying circuit and an output clamping circuit which are sequentially connected, wherein the input end of the signal processing circuit is used for receiving collected voltage and current signals, and is connected with the input end of the AD conversion circuit after filtering.
3. The grid harmonic detection device of claim 1, wherein: the phase voltage capturing and conditioning circuit for synchronous sampling comprises a voltage reduction circuit, a low-pass filter circuit, a phase shift circuit, a zero-crossing comparison circuit, a voltage amplification circuit and a light coupling isolation circuit, wherein the phase voltage capturing circuit is used for connecting a phase voltage signal which is synchronously acquired to a phase-locked loop PLL circuit after voltage reduction, filtering, phase shift, zero-crossing comparison and amplification to be used as a signal synchronous sampling mark.
4. The grid harmonic detection device of claim 1, wherein: the phase-locked loop PLL circuit adopts a CD4046 chip to realize the phase-locked function.
5. The grid harmonic detection device of claim 1, wherein: the AD conversion circuit for acquiring signals completes the function of acquiring and converting power grid data with high precision.
6. The grid harmonic detection device of claim 1, wherein: the processor for data processing adopts a data processor and comprises a data acquisition module for receiving acquired signals, an analysis module for processing the acquired signals, a compression module for storing data, a communication module for data transmission, a display module for displaying data and a management module for setting authority.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011550014.2A CN112595892A (en) | 2020-12-24 | 2020-12-24 | Power grid harmonic detection device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011550014.2A CN112595892A (en) | 2020-12-24 | 2020-12-24 | Power grid harmonic detection device |
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| CN112595892A true CN112595892A (en) | 2021-04-02 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203133168U (en) * | 2012-12-14 | 2013-08-14 | 浙江师范大学 | Power harmonic detector |
| JP2014023175A (en) * | 2012-07-12 | 2014-02-03 | Fuji Electric Co Ltd | Grid-connection device |
| CN209148771U (en) * | 2018-08-31 | 2019-07-23 | 国网江苏省电力有限公司徐州供电分公司 | A kind of Measurement of Harmonics in Power System device based on synchronized sampling complete cycle |
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2020
- 2020-12-24 CN CN202011550014.2A patent/CN112595892A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014023175A (en) * | 2012-07-12 | 2014-02-03 | Fuji Electric Co Ltd | Grid-connection device |
| CN203133168U (en) * | 2012-12-14 | 2013-08-14 | 浙江师范大学 | Power harmonic detector |
| CN209148771U (en) * | 2018-08-31 | 2019-07-23 | 国网江苏省电力有限公司徐州供电分公司 | A kind of Measurement of Harmonics in Power System device based on synchronized sampling complete cycle |
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Application publication date: 20210402 |