CN203133168U - Power harmonic detector - Google Patents
Power harmonic detector Download PDFInfo
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- CN203133168U CN203133168U CN 201220691916 CN201220691916U CN203133168U CN 203133168 U CN203133168 U CN 203133168U CN 201220691916 CN201220691916 CN 201220691916 CN 201220691916 U CN201220691916 U CN 201220691916U CN 203133168 U CN203133168 U CN 203133168U
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Abstract
The utility model provides a power harmonic detector which comprises a voltage sensor, a current sensor, a memory and a communication module, and further comprises a signal conditioning circuit for processing sampling signals, a phase-locked loop system, an A/D sampling circuit for acquiring signals, an embedded processor for processing data and an input and output device for man-machine interaction. The power harmonic detector meets the national standard precision requirement on harmonic test apparatuses. The fundamental amplitude error is less than 0.15%, the harmonic amplitude error is less than 3%, and the system frequency measurement error equals to or less than 0.01Hz. The power harmonic detector allows conducting harmonic tests for 2-60 times. The circuit design meets the related standard of international electronic equipment, satisfies the requirements of low power consumption, low radiation and anti-electromagnetic interference and is low in requirement on use environment. From the appearance aspect, the power harmonic detector is a hand-held device, and is small and portable. The power harmonic detector is provided with a protection device, which prevents the detector from being damaged by abnormity of extraneous environment or maloperation.
Description
Technical field
The utility model belongs to a kind of detector, specifically belongs to a kind of electric harmonic detector.
Background technology
When electric system normally moved, it supplied electric energy with rated voltage and rated frequency to the user.But in actual motion, load in the electrical network is constantly to change, include various non-linear power electronic equipments in the load, as inductance capacitance etc., particularly produce nonsinusoidal waveform inevitably at electron devices such as the extensive Switching Power Supply that adopts of electric equipment and electronic system control field, thyristors, bring disturbance to electrical network.Except these power electronic equipments, be mounted with nonlinear loads such as electric arc furnaces, frequency converter, rectifier, electric rotating machine in the electric power system, these loads are unlike the pure resistance consumer, they also consume a large amount of reactive powers and cause very big interference to electrical network when consuming active power, waveform in the power supply network is distorted, and no longer is the sine waveform of single rated frequency.Produce a large amount of frequencies in the electrical network greater than the current component of rated frequency, these frequencies are called harmonic component greater than the component of rated frequency.A large amount of generations of harmonic wave, becoming in the current power system influences one of key factor of the quality of power supply.Electric harmonic mainly shows the following aspects to the harm of electric system:
(1) harmonic wave is to the influence of circuit
(2) to the influence of power transformer
(3) to the influence of power capacitor
(4) to the influence of motor
(5) to the influence of relay protection and aut.eq.
(6) communication line is produced interference
The AC signal that electric harmonic detects mainly contains: voltage signal Ua, Ub, Uc, current signal Ia, Ib, Ic, Io(current in middle wire), the sample mode that adopts in the various monitoring instruments of electric system is generally at present: " multi-way switch+sampling maintenance+A/D conversion " pattern, this pattern hardware design is simple, cost is low.In the less demanding system of synchronism, can obtain good result.If but in frequency analysis, adopt this mode, even the situation of 128 of the samplings of ripple weekly this down, for 19 these harmonic waves, its phase place can be brought the error of 6 degree at least, this is for the system that the extraction fundametal compoment is carried out signal analysis, error can be ignored, and for the measurement of higher hamonic wave, will make measurement data not have confidence level.
Occur much about the electric harmonic pick-up unit both at home and abroad, external electric harmonic pick-up unit properties of product advanced person, applied widely, and it is durable reliable, but price is comparatively expensive, and at measurement function, measure aspects such as passage and data are complete existence defective in various degree, the home products price is lower, but manufacturing process is relatively poor, reliability and precision are generally not high and mostly can not be portable, mainly be applicable to the harmonic measure aspect, and in the analysis of higher hamonic wave, wave form analysis, the selection of sample window, data handle and as a result output facet and external product to compare gap bigger.
Summary of the invention
The purpose of this utility model provides a kind of measuring accuracy precision, can measure and handle electric power signal in real time, electric harmonic detector easy to carry.
The technical scheme that its technical matters that solves the utility model adopts is:
A kind of electric harmonic detector, comprise voltage sensor, the current sensor for detection of current signal, storer and communication module for detection of voltage signal, also comprise signal conditioning circuit, phase-locked loop systems, the A/D sample circuit that is used for gathering signal, the flush bonding processor of handling for sampled signal that is used for the data processing, the input-output device that is used for human-computer interaction;
-described signal conditioning circuit comprises the low pass anti-aliasing filter circuit that connects in turn, voltage follower circuit, signal conditioning circuit, the input end of low pass anti-aliasing filter circuit is used for receiving voltage, the current signal of gathering, the output terminal of signal conditioning circuit divides two-way, connects the input end of phase-locked loop systems, A/D sample circuit respectively;
-described phase-locked loop systems comprises phase detector, filtering circuit, level shifting circuit, function generator, described signal conditioning circuit output square wave is to an input end of phase detector, the output terminal of phase detector, through filtering circuit, level shifting circuit, to function generator, another input end that function generator output square wave turns back to phase detector constitutes phase-locked loop circuit.
Described level shifting circuit comprises voltage follower circuit and the amplifying circuit that links to each other successively, and the input end of voltage follower circuit connects the output terminal of filtering circuit, the input end of the output terminal contiguous function generator of amplifying circuit.
Described function generator comprises oscillating integrated circuit and the operational amplification circuit with multiple waveform output, the input end of function generator links to each other with level shifting circuit, the output terminal of function generator divides two-way, connects the input end of A/D sample circuit, phase detector respectively.
Described flush bonding processor comprises for the data acquisition module of reception collection signal, for the treatment of the analysis module of gathering signal, for the compression module of storage data, for the communication module of data transmission, for the display module that shows data, for the administration module of setting authority.
The beneficial effects of the utility model are, checkout equipment satisfies the accuracy requirement of GB harmonic wave testing tool, and the fundamental voltage amplitude error is less than 0.15%, and the harmonic wave amplitude error is less than 3%, and system frequency measuring error≤0.01Hz can carry out the test of 2～60 subharmonic.The circuit design aspect meets international electronic equipment relevant criterion, satisfies low-power consumption, and low radiation and anti-electromagnetic interference (EMI) requirement require low to environment for use.The outward appearance aspect is conceived to handheld device, guarantees that as far as possible volume is small and exquisite, is easy to carry about with one.Equipment has protective device, can prevent device damage unusual because of external environment or that the people causes for maloperation.
Device hardware has good extendability, and can make things convenient for according to demand increases or the removal function element.The software aspect adopts outstanding embedded OS and component technology, Application Program Interface close friend, easy operating.
Description of drawings
Below in conjunction with accompanying drawing the utility model is further specified.
Fig. 1 is hardware structure figure of the present utility model;
Fig. 2 is the required sine wave generating circuit principle assumption diagram of the utility model;
Fig. 3 is the required level shifting circuit schematic diagram of the utility model;
Fig. 4 is the utility model required input and modulate circuit schematic diagram;
Fig. 5 is the required sine wave generating circuit schematic diagram of the utility model;
Embodiment
U1, U2 operational amplifier among Fig. 3, R1-R4 resistance;
TR1 transformer among Fig. 4, U1 operational amplifier, R1-R9 resistance, C1-C3 electric capacity;
U1 function generator among Fig. 5, R1-R6 resistance, RV1-RV4 rheostat, C1 electric capacity.
Input end with reference to the described signal conditioning circuit 1 of Fig. 1 is connected with current sensor 3 with voltage sensor 2, output terminal is connected with the input end of phase-locked loop systems 4, the input end of A/D sample circuit 5 respectively, the input end of A/D sample circuit 5 is connected with the output terminal of phase-locked loop systems 4, output terminal is connected with flush bonding processor 6, and flush bonding processor 6 is connected with storer 7, input-output device 8 and communication module 9.
According to Fig. 2, voltage transformer (VT) 1 is gathered line voltage, by signal conditioning circuit 2, be input to an input end of phase detector 3, from the output terminal of phase detector 3, output signal, through filtering circuit 4, level shifting circuit 5, input function generator 6, function generator 6 output square waves 7 turn back to another input end of phase detector 3, and function generator 6 sine wave outputs are to the A/D sample circuit.
According to the described input of Fig. 4 and modulate circuit, operational amplifier U1B constitutes voltage follower circuit, operational amplifier U1A, resistance R 1-R4, capacitor C 1, C2 constitute low pass anti-aliasing filter circuit, and operational amplifier U1C, resistance R 6-R9, capacitor C 3 constitute signal conditioning circuit.
Need in the harmonic wave detection algorithm that system adopts to use with the synchronous cosine and sine signal of line voltage as reference signal, described signal obtain the method that can adopt phaselocked loop to add the sin cos functions generator, the method that adds Sine Function Generator by phaselocked loop, but the frequency of automatic real-time track line voltage and phase place, do not take soft, the hardware resource of microprocessor, greatly reduce the complexity of harmonic wave detection algorithm programming.
Case study on implementation: the voltage signal Ua that voltage sensor 2 is measured among Fig. 1, Ub, Uc, the current signal Ia that current sensor 3 is measured, Ib, Ic, neutral signal Io is directly inputted to signal conditioning circuit 1, with reference to figure 4, described signal conditioning circuit 1 can cooperate integrated transporting discharging LM2902 to form by precision resistance, by voltage transformer (VT) 2, and current transformer 3, after the low pass anti-aliasing filter processing of circuit, filtering high-frequency signal part, making the signal that is input to the back level is band-limited signal, through the voltage follower circuit in the signal conditioning circuit, circuit is to the influence of signals collecting before and after avoiding, by signal conditioning circuit, suppress to be brought by the variation of external condition the influence of circuit, the ripple in the elimination rectifier output voltage again.Added low pass anti-aliasing filter circuit in this enforcement in the signal conditioning circuit, add each passage of A/D sampling A itself and all have built-in anti-confusion filtering device, this makes this detector have good antijamming capability and anti-aliasing performance, guarantees that processor carries out the FFT computing and can take accurate result to when finishing spectrum analysis.
This signal is divided into two-way, and one the tunnel sends into phase-locked loop systems 4, for realizing frequency measurement and signal is prepared synchronously that A/D sample circuit 5 is sent on another road, signal is sampled and is kept.
Directly as an input of phase detector among Fig. 23, phase detector 3, filtering circuit 4, level shifting circuit 5 and function generator 6 are formed a phaselocked loop (PLL) circuit to one road signal.When loop-locking, the sine wave that output is synchronous with line voltage, namely with the frequency homophase, and almost do not postpone in time, described phase detector 3 uses the PDI of CD4O46, described filtering circuit 4 is made of resistance and electric capacity, by level shifting circuit 5 input function generators 6, level shifting circuit is with reference to shown in Figure 4, be composed in series by two operational amplifier OP07, function generator is with reference to Fig. 5, and the sinusoidal wave degree of distortion of function generator ICL8O38 is adjusted pin 1 and 12 by rheostat RV2, RV3, resistance R 4, R5 constitutes bridge circuit, and degree of distortion is reduced to about 0.1%.Pin 2 is sine wave output.Square wave output pin 9 meets a pull-up resistor R3 and arrives+12V, makes the square wave level of exporting between scholar 12V.The square wave process level shifting circuit of output, operational amplifier U2, resistance R 6 constitutes level shifting circuits, as another input of phase detector 3.Because 900 differ arranged between the square wave of ICL8038 output and the sine wave, when loop-locking, just in time satisfy PDI input and output waveform duty cycle and be 50% requirement, export one and the equal signal of mains frequency, namely realize frequency-tracking with phaselocked loop.This signal input A/D sample circuit as synchronous control signal, is used for the startup of control sample circuit, realizes the synchronized sampling to signal, sends into processor then, carries out frequency measurement by it.
By by having 6 tunnel 16 A/D sample circuits 5 that HIGH-SPEED HIGH-ACCURACY A ADS8364 constitutes independently, the synchronous control signal that receives from phase-locked loop systems 4 carries out behind synchronized sampling, quantification, the coding analog signal conversion of importing being become discrete signal to input signal, by analog to digital conversion, input flush bonding processor C5410.Described converter can guarantee that 6 tunnel simulating signals sample simultaneously, and in conversion process, postpone very little, thereby reduced effectively because the phase error that the sampling time difference produces, and sampling rate and input signal gain all are programmable.
Flush bonding processor receives the signal of sample circuit input earlier by signal acquisition module, carries out the analytical calculation of harmonic wave, a harmonic wave and dynamic harmonic again by analysis module.
Earlier select window width with adaptive algorithm
The best method of avoiding spectrum leakage is exactly one or more signal periods that the window width selected just in time covers signal.The spectrum leakage problem that runs into when carrying out the detection of harmonic wave and a harmonic wave under the changeable and harmonic components condition of unknown in system frequency, this adaptive algorithm based on iterative program provides a desirable solution.
Suppose a signal is arranged
, its medium frequency
It is a random number.The setting sample frequency is
, the hits of each period T is expressed as
, this is a random number and is not an integer in the ordinary course of things.If
, wherein
With
For highest common factor is two integers of 1, use
Multiply by
Obtain
,
Covered
The individual cycle (an integral multiple cycle) is in the cycle
Interior hits is expressed as
, this is a positive integer and has always covered an integral multiple period T that namely N is the sampling period signal
The discrete-time signal that obtains
(such as
, wherein
Be integer) cycle.If use
Individual sample is done the DFT conversion, does not just have the spectrum leakage effect among that result.From
Formula as can be seen,
It is the sampling period signal
The discrete-time signal that obtains
Cycle.If use
Individual sample is done the DFT conversion, does not just have the spectral leakage effect among that result.From
As can be seen, the cycle
It is signal frequency
And sample frequency
A function.
Signal
, wherein
When
Be integer, expression has a harmonic components; When
, wherein
,
Be two integers of 1 for highest common factor.It is updated to
, can obtain:
Here first-harmonic is
Two harmonic waves, the cycle of its discrete-time signal can by
Obtain.
When signal contains a harmonic wave, cycle
It is the function of signal frequency, sample frequency and a harmonic components.If a burst has
The cycle of individual sample, so this
Individual sample can repeat in the next adjacent cycle.This is the automatic searching cycle
Digital algorithm a point of penetration is provided.
Suppose the discrete-time signal S that a unlimited size is arranged:
This signal is a vector that value sequence is arranged.The correlativity of two discrete signals can be estimated with the dot product of two vectors.Based on formula
This algorithm has defined a related coefficient
, determine the similarity of two sequences with this.Correlation when parallel and direction is consistent when two signal phasors
Be maximal value 1, correlation when the parallel but direction of two signal phasors is opposite
Be minimum value.
For the automatic algorithm that calculates the window width proposition is an iteration optimum procedure, this program utilizes the local period (or local similar) of burst to search for optimal window width, and burst wherein satisfies the periodicity necessary condition of DFT.When the correlativity of two adjacent parts did not satisfy predetermined termination rules, the signal length of first part just was increased a sample, and made comparisons with the next adjacent part that equal length is arranged, and repeated continuously up to satisfying termination rules then.The setting of the termination rules of determining and searching for of the initial value of signal length is two matters of utmost importance that are directly connected to this algorithm complex.
The spectrum leakage problem that runs into when carrying out the detection of harmonic wave and a harmonic wave under the changeable and harmonic components condition of unknown in system frequency, this adaptive algorithm based on iterative program provides a desirable solution.Select this adaptive algorithm based on following some consideration, this some also be the advantage place of this algorithm simultaneously.
No matter in the signal between harmonic components how, no matter also how system frequency changes, always this algorithm is effectively and accurate.
2. the spectrum leakage error can be estimated roughly with the value of read cycle index gauge.When the way that must take to compromise or when signal during from a transition between states to another state, this period indicator provides very Useful Information.
3. when system frequency changed, this algorithm can be sought a new window width automatically according to sample frequency.
Again sampled point is adopted the FFT conversion
When utilizing iterative program to try to achieve sample number when satisfying termination rules, jump out iterative program, enter the 3rd link of algorithm, that is, do the FFT computing of sample.Shown in fft algorithm is achieved as follows:
The fast Fourier algorithm of 2 time-divisions of base is a kind of fft algorithm that is most widely used.The fast Fourier algorithm of 2 time-divisions of base is theoretical foundation with basic 2 time-division butterfly operations.
Base 2 time-division butterfly operation theorems are:
If sequence
Length is N,
,
, n, k, m are integer,
,
, if
,
Then:
The result who obtains by analysis module, show at output device by display module, the mode of taking picture to add data make the user get information about the problem that exists of the electric power that detects, can also store by compression module, or transmit by communication module.
Claims (4)
1. electric harmonic detector, comprise voltage sensor (2), the current sensor (3) for detection of current signal, storer (7) and communication module (9) for detection of voltage signal, it is characterized in that: described electric harmonic detector also comprises signal conditioning circuit (1), phase-locked loop systems (4), the A/D sample circuit (5) that is used for gathering signal, the flush bonding processor of handling for sampled signal (6) that is used for the data processing, the input-output device (8) that is used for human-computer interaction;
-described signal conditioning circuit (1) comprises signal conditioning circuit, voltage follower circuit and the filtering circuit that connects in turn, the input end of signal conditioning circuit is used for receiving voltage, the current signal of gathering, the output terminal of filtering circuit divides two-way, connects the input end of phase-locked loop systems (4), A/D sample circuit (5) respectively;
-described phase-locked loop systems (4) comprises phase detector (10), filtering circuit (11), level shifting circuit (12), function generator (13), described signal conditioning circuit (1) output waveform is to an input end of phase detector (10), the output terminal of phase detector (10), to function generator (13), another input end that function generator (13) output square wave (14) turns back to phase detector (10) constitutes phase-locked loop circuit through filtering circuit (11), level shifting circuit (12).
2. electric harmonic detector according to claim 1, it is characterized in that: described level shifting circuit (12) comprises voltage follower circuit and the amplifying circuit that links to each other successively, the input end of voltage follower circuit connects the output terminal of filtering circuit, the input end of the output terminal contiguous function generator (13) of amplifying circuit.
3. electric harmonic detector according to claim 1, it is characterized in that: described function generator (13) comprises oscillating integrated circuit and the operational amplification circuit with multiple waveform output, the input end of function generator (13) links to each other with level shifting circuit (12), the output terminal of function generator (13) divides two-way, connects the input end of A/D sample circuit (5), phase detector (10) respectively.
4. electric harmonic detector according to claim 1 is characterized in that: described flush bonding processor (6) comprise for receive the data acquisition module of gathering signal, for the treatment of the analysis module of gathering signal, be used for the storage data compression module, be used for data transmission communication module, be used for showing data display module, be used for setting the administration module of authority.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201220691916 CN203133168U (en) | 2012-12-14 | 2012-12-14 | Power harmonic detector |
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|---|---|---|---|
| CN 201220691916 CN203133168U (en) | 2012-12-14 | 2012-12-14 | Power harmonic detector |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103604990A (en) * | 2013-11-27 | 2014-02-26 | 国家电网公司 | Power harmonic wave detection and analysis equipment |
| CN103956827A (en) * | 2014-04-23 | 2014-07-30 | 国家电网公司 | Harmonic monitoring control system based on multi-source microgrid |
| CN105974179A (en) * | 2016-07-01 | 2016-09-28 | 河北箱变电器有限公司 | Secondary equipment for monitoring partial discharge and temperature monitoring device |
| CN106405411A (en) * | 2016-11-23 | 2017-02-15 | 国家电网公司 | Digital integration method breaker dielectric loss angle tangent value online monitoring system and method thereof |
| CN106771510A (en) * | 2015-11-23 | 2017-05-31 | 中国电力科学研究院 | A kind of method for improving residual current lower range certainty of measurement |
| CN108872782A (en) * | 2018-05-18 | 2018-11-23 | 江苏伊莱尔电力科技有限公司 | A kind of mains by harmonics on-line measuring device and method |
| CN109581028A (en) * | 2018-11-30 | 2019-04-05 | 国网福建省电力有限公司 | A kind of direct current transportation harmonic detecting system and its implementation |
| CN112595892A (en) * | 2020-12-24 | 2021-04-02 | 哈尔滨理工大学 | Power grid harmonic detection device |
| CN113341226A (en) * | 2021-06-21 | 2021-09-03 | 合肥美的暖通设备有限公司 | Harmonic detection method, device, frequency converter and storage medium |
-
2012
- 2012-12-14 CN CN 201220691916 patent/CN203133168U/en not_active Expired - Fee Related
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103604990A (en) * | 2013-11-27 | 2014-02-26 | 国家电网公司 | Power harmonic wave detection and analysis equipment |
| CN103956827A (en) * | 2014-04-23 | 2014-07-30 | 国家电网公司 | Harmonic monitoring control system based on multi-source microgrid |
| CN106771510A (en) * | 2015-11-23 | 2017-05-31 | 中国电力科学研究院 | A kind of method for improving residual current lower range certainty of measurement |
| CN106771510B (en) * | 2015-11-23 | 2020-01-24 | 中国电力科学研究院 | Method for improving low-range measurement precision of residual current |
| CN105974179A (en) * | 2016-07-01 | 2016-09-28 | 河北箱变电器有限公司 | Secondary equipment for monitoring partial discharge and temperature monitoring device |
| CN106405411A (en) * | 2016-11-23 | 2017-02-15 | 国家电网公司 | Digital integration method breaker dielectric loss angle tangent value online monitoring system and method thereof |
| CN106405411B (en) * | 2016-11-23 | 2023-09-22 | 国家电网公司 | Digital integration method breaker dielectric loss tangent value on-line monitoring system and method |
| CN108872782A (en) * | 2018-05-18 | 2018-11-23 | 江苏伊莱尔电力科技有限公司 | A kind of mains by harmonics on-line measuring device and method |
| CN109581028A (en) * | 2018-11-30 | 2019-04-05 | 国网福建省电力有限公司 | A kind of direct current transportation harmonic detecting system and its implementation |
| CN112595892A (en) * | 2020-12-24 | 2021-04-02 | 哈尔滨理工大学 | Power grid harmonic detection device |
| CN113341226A (en) * | 2021-06-21 | 2021-09-03 | 合肥美的暖通设备有限公司 | Harmonic detection method, device, frequency converter and storage medium |
| CN113341226B (en) * | 2021-06-21 | 2022-04-29 | 合肥美的暖通设备有限公司 | Harmonic detection method, device, frequency converter and storage medium |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130814 Termination date: 20131214 |