CN102288820A - Harmonic detecting method based on combination of phase-locked loop and neural network - Google Patents
Harmonic detecting method based on combination of phase-locked loop and neural network Download PDFInfo
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Abstract
The invention relates to a harmonic detecting method based on combination of a phase-locked loop and a neural network. A three-phase current passes through the phase-locked loop to obtain a sinusoidal signal with amplitude value of 1 and the same phase with fundamental amplitude, the obtained sinusoidal signal is multiplied by current fundamental amplitude calculated by the neural network to obtain a fundamental harmonic current signal, and the acquired three-phase power grid current is subtracted by the fundamental harmonic current signal to obtain a pure harmonic signal. The method relates to no low pass filter component, thus system delay caused by a difference equation of a low pass filter is avoided, and composition of the neural network is basically formed by multiplication and add operations, thus being applicable to realization of a DSP (digital signal processing); besides, output of offline neural network training only requires the fundamental amplitude, and the fundamental amplitude can be calculated by adopting the traditional Fourier transformation, thus being not complex and improving accuracy and instantaneity of the harmonic detection. The method provided by the invention is also applicable to technical application.
Description
Technical field
The present invention relates to a kind of electrical technology, particularly a kind of harmonic detecting method that combines based on phaselocked loop and neural network.
Background technology
Along with the development of Power Electronic Technique, the pollution of mains by harmonics is also more and more serious.Active Power Filter-APF is a kind of electric device that harmonic wave suppresses that is specifically applied to, its principle is that control main circuit generation harmonic wave identical with the mains by harmonics current amplitude, that phase place is opposite is offset mains by harmonics after detecting the mains by harmonics electric current, thereby make power network current approach sine wave, reach prescribed level.Traditional harmonic detecting method is based on the ip-iq method of instantaneous reactive power theory, and the shortcoming of this harmonic detecting method is that accuracy of detection is low, and has the delay of certain hour, and real-time is poor.
Summary of the invention
The present invention be directed to the low problem of present harmonic detecting method precision, proposed a kind of harmonic detecting method that combines based on phaselocked loop and neural network, to improve precision and the real-time that harmonic wave detects further.
Technical scheme of the present invention is: a kind of harmonic detecting method that combines based on phaselocked loop and neural network comprises following concrete steps:
1) foundation of neural network: gather three phase network current data sample of signal, under the off-line state it is carried out Fourier transform, calculate the fundamental current amplitude, with the input as neural network of the three-phase current peak value that calculates in the three-phase current signal gathered and the last power frequency period, the three-phase current fundamental voltage amplitude that Fourier transform calculates is as the output of neural network;
2) fundamental current signal: neural network is put into the Active Power Filter-APF system, calculate the fundamental current amplitude according to input in real time; Gathering the three phase network electric current simultaneously is 1 through obtaining amplitude behind the phaselocked loop, the sinusoidal signal that phase place is identical with fundamental voltage amplitude, and the current first harmonics amplitude that this sinusoidal signal that obtains and neural network are calculated multiplies each other and obtains the fundamental current signal;
3) with step 2) the three phase network current signal gathered deducts step 2) the fundamental current signal that calculates, just can obtain pure harmonic signal.
Beneficial effect of the present invention is: the present invention is based on the harmonic detecting method that phaselocked loop and neural network combine, do not relate to the low-pass filter composition, thereby avoided because the difference equation of low-pass filter causes the delay in the system, and the formation of neural network is made of multiplication and additive operation substantially, be fit to very much the realization of DSP, in addition, the output of off-line neural metwork training only needs fundamental voltage amplitude, utilize traditional Fourier transform just can calculate, and uncomplicated, improve precision and real-time that harmonic wave detects.Also be applicable to the application on the engineering.
Description of drawings
Fig. 1 is the neural network structure synoptic diagram that the present invention is used to detect fundamental voltage amplitude;
Fig. 2 is a Harmonics Calculation FB(flow block) of the present invention;
Fig. 3 is the harmonic detecting method synoptic diagram that phaselocked loop of the present invention and neural network combine;
Fig. 4 the present invention is based on the Active Power Filter-APF workflow diagram that harmonic wave that phaselocked loop combines with neural network detects.
Embodiment
At first gather abundant three phase network current data sample of signal, under the off-line state it is carried out Fourier transform, calculate the fundamental current amplitude.With the input of the three-phase current peak value that calculates in the three-phase current signal gathered and the last power frequency period as neural network, the three-phase current fundamental voltage amplitude that Fourier transform calculates is as the output of neural network, hidden layer is got 35 neurons, this neural network is carried out off-line training, and the structure of neural network as shown in Figure 1.
The neural network that trains is put into the Active Power Filter-APF system, calculate the fundamental current amplitude according to input in real time.Simultaneously, three-phase current is 1 through obtaining amplitude behind the phaselocked loop, the sinusoidal signal that phase place is identical with fundamental voltage amplitude, the current first harmonics amplitude that this signal and neural network are calculated can obtain the fundamental current signal mutually at convenience, at this moment, three-phase current signal with former collection deducts the fundamental current signal that calculates, and just can obtain pure harmonic signal, and its Harmonics Calculation process is shown in Fig. 2,3.
Utilize the detected pure harmonic current of this method that the Active Power Filter-APF main circuit is controlled, make main circuit produce the harmonic current opposite and inject electrical network with electrical network, harmonic current is offset, make power network current reach prescribed level, thereby realized the process of inhibition of harmonic wave, the entire work process of Active Power Filter-APF as shown in Figure 4.Wherein, harmonic wave detects link and is realized that by digital signal processor DSP the main circuit controlling unit is realized by FPGA.Because the method that this paper proposes does not relate to the low-pass filter composition, thereby avoided because the difference equation of low-pass filter causes the delay in the system, and the formation of neural network is made of multiplication and additive operation substantially, be fit to very much the realization of DSP, in addition, the output of off-line neural metwork training only needs fundamental voltage amplitude, utilize traditional Fourier transform just can calculate, and uncomplicated, therefore, this cover detection method also is applicable to the application on the engineering.
Claims (1)
1. a harmonic detecting method that combines based on phaselocked loop and neural network is characterized in that, comprises following concrete steps:
1) foundation of neural network: gather three phase network current data sample of signal, under the off-line state it is carried out Fourier transform, calculate the fundamental current amplitude, with the input as neural network of the three-phase current peak value that calculates in the three-phase current signal gathered and the last power frequency period, the three-phase current fundamental voltage amplitude that Fourier transform calculates is as the output of neural network;
2) fundamental current signal: neural network is put into the Active Power Filter-APF system, calculate the fundamental current amplitude according to input in real time; Gathering the three phase network electric current simultaneously is 1 through obtaining amplitude behind the phaselocked loop, the sinusoidal signal that phase place is identical with fundamental voltage amplitude, and the current first harmonics amplitude that this sinusoidal signal that obtains and neural network are calculated multiplies each other and obtains the fundamental current signal;
3) with step 2) the three phase network current signal gathered deducts step 2) the fundamental current signal that calculates, just can obtain pure harmonic signal.
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Cited By (7)
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|---|---|---|---|---|
| CN102593862A (en) * | 2012-02-02 | 2012-07-18 | 广西师范大学 | Photovoltaic grid-connected inverter and control method thereof |
| CN103383413A (en) * | 2013-07-09 | 2013-11-06 | 温州大学 | Real-time harmonic detection method based on direct weight determination method |
| CN103424621A (en) * | 2013-08-20 | 2013-12-04 | 江苏大学 | Artificial neural network detecting method of harmonic current |
| CN107144767A (en) * | 2017-07-20 | 2017-09-08 | 云南电网有限责任公司电力科学研究院 | A kind of accident indicator and fault-signal detection method |
| CN107367647A (en) * | 2017-06-22 | 2017-11-21 | 上海理工大学 | The detection of mains by harmonics source and localization method based on EEMD SOM |
| CN108152584A (en) * | 2017-12-21 | 2018-06-12 | 中南大学 | A kind of high ferro tractive power supply system harmonic wave Multi-path synchronous rapid detection method |
| CN109030938A (en) * | 2017-06-08 | 2018-12-18 | 许继集团有限公司 | A kind of anti-harmonic wave frequency measuring method and device based on sine filtering |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102593862A (en) * | 2012-02-02 | 2012-07-18 | 广西师范大学 | Photovoltaic grid-connected inverter and control method thereof |
| CN102593862B (en) * | 2012-02-02 | 2014-11-05 | 广西师范大学 | Photovoltaic grid-connected inverter and control method thereof |
| CN103383413A (en) * | 2013-07-09 | 2013-11-06 | 温州大学 | Real-time harmonic detection method based on direct weight determination method |
| CN103424621A (en) * | 2013-08-20 | 2013-12-04 | 江苏大学 | Artificial neural network detecting method of harmonic current |
| CN109030938A (en) * | 2017-06-08 | 2018-12-18 | 许继集团有限公司 | A kind of anti-harmonic wave frequency measuring method and device based on sine filtering |
| CN109030938B (en) * | 2017-06-08 | 2021-05-11 | 许继集团有限公司 | Anti-harmonic frequency measurement method and device based on sine filtering |
| CN107367647A (en) * | 2017-06-22 | 2017-11-21 | 上海理工大学 | The detection of mains by harmonics source and localization method based on EEMD SOM |
| CN107144767A (en) * | 2017-07-20 | 2017-09-08 | 云南电网有限责任公司电力科学研究院 | A kind of accident indicator and fault-signal detection method |
| CN107144767B (en) * | 2017-07-20 | 2023-06-02 | 云南电网有限责任公司电力科学研究院 | Fault indication device and fault signal detection method |
| CN108152584A (en) * | 2017-12-21 | 2018-06-12 | 中南大学 | A kind of high ferro tractive power supply system harmonic wave Multi-path synchronous rapid detection method |
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