CN107271772A - A kind of mains frequency quick determination method of high accuracy and anti-noise jamming - Google Patents
A kind of mains frequency quick determination method of high accuracy and anti-noise jamming Download PDFInfo
- Publication number
- CN107271772A CN107271772A CN201710437135.8A CN201710437135A CN107271772A CN 107271772 A CN107271772 A CN 107271772A CN 201710437135 A CN201710437135 A CN 201710437135A CN 107271772 A CN107271772 A CN 107271772A
- Authority
- CN
- China
- Prior art keywords
- phase
- frequency
- closed loop
- mains
- loop detection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
- G01R23/12—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage by converting frequency into phase shift
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Frequencies, Analyzing Spectra (AREA)
Abstract
The invention discloses a kind of high accuracy and the mains frequency quick determination method of anti-noise jamming, link and frequency closed loop detection are calculated including synchronized phase open loop detection, beat frequency phase, the mains voltage signal detected can be obtained into the locking phase of power network in real time through synchronized phase open loop detection, link is calculated by beat frequency phase and extracts beat frequency phase in synchronized phase, and by beat frequency phase information incoming frequency closed loop detection to obtain the real-time frequency of power network.The present invention is effectively improved the detectability of power network real-time frequency, and measurement accuracy is high, fast response time, good in anti-interference performance, can solve closed loop and survey the stability problem of phase, frequency measuring method under weak power grid environment, with good application value.
Description
Technical field：
The invention belongs to mains frequency detection technique field, the mains frequency of more particularly to a kind of high accuracy and anti-noise jamming is fast
Fast detection method.
Background technology：
Frequency is electrical energy production, consumes prerequisite quality inspection index, is also the important of measurement operation states of electric power system
Parameter, regenerative resource accesses the precision and real-time that power network detects to mains frequency and proposes higher requirement on a large scale.It is existing
Some frequency detecting methods have to rely on phaselocked loop, also referred to as soft phase-locked loop (software phase-locked loop, SPLL).
Typical SPLL mainly has 3 kinds：Single synchronous coordinate system SPLL (single synchronous reference frame SPLL,
SSRF-SPLL), the SSRF-SPLL based on symmetrical component method, the decoupling SPLL (decoupled based on double synchronous coordinate systems
Double SRF-SPLL, DDSRF- SPLL).Wherein, amplitude, frequency when SSRF-SPLL can be effectively applied to grid balance
Rate and phase-detection, its dynamic, steady-state response performance are preferable.But, when unbalanced power supply, the frequency of SSRF-SPLL outputs
There is harmonic wave in rate, therefore steady-state behaviour is bad.Improve SSRF-SPLL and positive sequence voltage component separated using symmetrical component method,
And be sent to after closed-loop regulator and can obtain the frequency of unbalanced power grid.However, the method use preset parameter
All-pass filter, when power network occurrence frequency drifts about, the accuracy of frequency detecting is poor.DDSRF-SPLL is then employed and is based on
Double synchronous coordinate architectures of positive and negative sequence, realize the decoupling of positive-negative sequence, efficiently solve frequency detecting during asymmetrical three-phase
Problem.However, the coupling between use and pi regulator and 4 low pass filters due to double synchronous coordinate architectures,
So that the dynamic process of this method is sufficiently complex, its longer response time can not meet requirement of the frequency detecting to rapidity.
In addition, SPLL loop filter nearly all employs pi regulator, therefore its dynamic response time depends mainly on adjuster
Characteristic.When power grid environment is more severe, regulator parameter is difficult to optimize design, and adjuster dynamic process it is time-consuming compared with
Long, existing SPLL response time is nearly all more than 1 power frequency period, it is impossible to meet the requirement for quick and precisely detecting frequency.
Eliminate closed loop regulation process and be then remarkably improved frequency detecting speed, this is also the starting point of open loop detection, but line voltage
When there is HF noise signal, the phase of divided ring method detection differentiate that noise signal can be amplified, and causes frequency to be examined
There is larger error in survey.
Above-mentioned method is all clearly disadvantageous in the presence of some, and preferable mains frequency detection technique should be met accurately simultaneously
Property, rapidity, noise immunity requirement, detection method should also be simple and easy to apply in addition, in order in embedded controller
Realize.
The content of the invention：
Must be realized for the detection of existing mains frequency by phaselocked loop, under weak power grid environment phaselocked loop exist it is intrinsic
Negative resistance character can cause local power system to occur low-frequency oscillation, it is impossible to accurate to obtain mains frequency information, and the present invention is disclosed
A kind of mains frequency quick determination method of high accuracy and anti-noise jamming, this method based on open loop detect it is accurate in real time
Phase information, by extracting beat frequency phase therein, and the frequency that can obtain accurate power network through difference frequency closed loop detection is believed
Breath.
The technical solution adopted in the present invention is：A kind of quick detection side of the mains frequency of high accuracy and anti-noise jamming
Method, including synchronized phase open loop detection, beat frequency phase calculate link and frequency closed loop detection, by power network
Voltage signalU a、U b、U cThe locking phase of power network can be obtained after synchronized phase open loop detection, is passed through
Difference frequency signal calculate link can extract the beat frequency phase in synchronized phase signal, by this beat frequency phase signal input to
The real-time frequency of power network can be obtained after frequency closed loop detectionf。
General principle to synchronized phase open loop detection method is described in detail herein below：
Three-phase power grid voltage can be described with following expression：
(1)
After the rotated coordinate transform of line voltageU d、U qIt is as follows：
Assuming that initial phaseθ∈ (0,2 π), according to additional angleθ exThe locking phase that selection rule can obtain power network is as follows：
(3)
Wherein, arctan (U q/U d)+ θ ex As beat frequency phase.
Frequency capture method is as follows：
（1）Mains voltage signal is gathered by voltage sensorU a、U b、U c；
（2）The mains voltage signal collected is synchronized into rotating coordinate transformation by synchronous rotating angle module, obtained
Voltage signal under to two-phase rotating coordinate systemU d 、U q；
（3）If there are high-frequency noise or harmonic components in the mains voltage signal collected, need in synchronously rotating reference frame
Increase filter module after conversion module, to step（2）In output signal be filtered, to eliminate the shadow of noise, harmonic wave
Ring；
（4）According to step（3）ObtainU d、U q, select correct by Rule of judgmentθ ex, Rule of judgment is as follows：IfU d>0 andU q>
0, thenθ ex=0；IfU d<0, thenθ ex=π；IfU d>0 andU q<0, thenθ ex=2π；
（5）According to step（3）、（4）Obtained parameterU d 、U q 、θ ex, electricity is calculated with reference to amplitude disclosed by the invention, phase formula
The real-time amplitude and phase of net voltage；Wherein, amplitude calculation formula is：, phase calculation formula is：；Wherein,ω s tAs operating frequency phase；arctan(U q/U d)+θ exAs beat frequency phase.
（6）The beat frequency phase extracted in synchronized phase is designated asx, being postponed a sampling period is designated asY,By the cycle
CounternInitial value be set to 0, the phase information of the part is exported after calculating link adjustment through beat frequency phase, is designated as phase,
Wherein phase=x+2*π*n；
（7）By step（6）Output postpone a sampling period postscript beθ, the input adjusted as closed loop, it is defeated that closed loop is adjusted
Go out it is integrated after as feedback signalθ feedback, the output that both differences are adjusted after being adjusted through PI as closed loop, by itself divided by 2
π obtains difference frequency Δf。
（8）By difference frequency ΔfThe actual frequency that can obtain power network is superimposed with power frequency (China is 50Hz)f。
In addition, the simulation model of the mains frequency quick determination method by building high accuracy and anti-noise jamming, to this
Plant frequency detecting method and carry out simulating, verifying, simulation result also confirms the correctness and validity of the program simultaneously.
By above-mentioned technical proposal, beneficial effects of the present invention are：Compared with existing frequency detecting method, the present invention is public
The grid frequency detection method opened is to be based on accurate real-time phase information, and real-time phase information can accurately be obtained, is not present
Closed loop surveys the intrinsic stability problem of phase system；Closed loop frequency measuring method based on real-time accurate phase information, which is avoided, to be believed phase
Breath carries out calculus of differences, therefore anti-noise jamming ability is strong, can obtain high-precision mains frequency information.
Brief description of the drawings：
Fig. 1 is the schematic diagram of synchronized phase open loop detection in the present invention；
Fig. 2 is the schematic diagram of beat frequency phase calculating link in the present invention；
Fig. 3 is the schematic diagram of frequency closed loop detection in the present invention；
Fig. 4 is the three-phase power grid voltage waveform of Noise；
Simulation waveform comparison diagram when Fig. 5 has high-frequency noise before and after mains frequency mutation.
Embodiment：
The present invention is described in further detail below in conjunction with the accompanying drawings.
Fig. 1-3 is frequency acquisition schematic diagram of the present invention, including：Three-phase power grid voltage signalU a、U b、U c, synchronized phase
Open loop detection, beat frequency phase calculate link, frequency closed loop detection.
Fig. 4 is the three-phase power grid voltage waveform of Noise, and voltage initial magnitude is 1p.u, is changed into 1.5p.u. during 2.5s.
Fig. 5 is that, in the case where there is high-frequency noise, simulation waveform comparison diagram before and after mains frequency mutation, line voltage is initial
Frequency is 60Hz, in 2.5s, and frequency discontinuity is 50Hz.
As Figure 1-3, the quick determination method of the mains frequency of a kind of high accuracy and anti-noise jamming, including power network are same
Walk phase open loop detection, beat frequency phase and calculate link and frequency closed loop detection, as shown in Figure 1 by line voltage
SignalU a、U b、U cThe locking phase of power network can be obtained after synchronized phase open loop detection, passes through difference frequency
Signal of change link can extract the beat frequency phase in synchronized phase signal, and this beat frequency phase signal is inputted to frequency
The real-time frequency of power network can be obtained after closed loop detectionf。
General principle to synchronized phase open loop detection method is described in detail herein below：
Three-phase power grid voltage can be described with following expression：
(1)
After the rotated coordinate transform of line voltageU d、U qIt is as follows：
Assuming that initial phaseθ∈ (0,2 π), according to additional angleθ exThe locking phase that selection rule can obtain power network is as follows：
(3)
Wherein, arctan (U q/U d)+ θ ex As beat frequency phase.
Frequency capture method is as follows：
（1）Mains voltage signal is gathered by voltage sensorU a、U b、U c；
（2）The mains voltage signal collected is synchronized into rotating coordinate transformation by synchronous rotating angle module, obtained
Voltage signal under to two-phase rotating coordinate systemU d 、U q；
（3）If there are high-frequency noise or harmonic components in the mains voltage signal collected, need in synchronously rotating reference frame
Increase filter module after conversion module, to step（2）In output signal be filtered, to eliminate the shadow of noise, harmonic wave
Ring；
（4）According to step（3）ObtainU d、U q, select correct by Rule of judgmentθ ex, Rule of judgment is as follows：IfU d>0 andU q>
0, thenθ ex=0；IfU d<0, thenθ ex=π；IfU d>0 andU q<0, thenθ ex=2π；
（5）According to step（3）、（4）Obtained parameterU d 、U q 、θ ex, electricity is calculated with reference to amplitude disclosed by the invention, phase formula
The real-time amplitude and phase of net voltage；Wherein, amplitude calculation formula is：, phase calculation formula is：；Wherein,ω s tAs operating frequency phase；arctan(U q/U d)+θ exAs beat frequency phase；
（6）The beat frequency phase extracted in synchronized phase is designated asx, being postponed a sampling period is designated asY,By cycle count
DevicenInitial value be set to 0, comparexWithySize, if (y-x) it is more than threshold value M（The M π of theoretical value 2, it is contemplated that discrete sampling
Error caused by process, M value, which should take, is slightly less than 2 π, and the sampling period is bigger, and threshold value should be smaller）, then cycle rate counternFrom increasing
1, it is otherwise not rightnAdded up, the phase information of the part is exported after calculating link adjustment through beat frequency phase, is designated as phase, its
Middle phase=x+2*π*n；
（7）By step（6）Output postpone a sampling period postscript beθ, the input adjusted as closed loop, it is defeated that closed loop is adjusted
Go out it is integrated after as feedback signalθ feedback, the output that both differences are adjusted after being adjusted through PI as closed loop, by itself divided by 2
π obtains difference frequency Δf。
（8）By difference frequency ΔfThe actual frequency that can obtain power network is superimposed with power frequency (China is 50Hz)f。
In addition, the simulation model of the mains frequency quick determination method by building high accuracy and anti-noise jamming, to this
Plant frequency detecting method and carry out simulating, verifying, simulation result also confirms the correctness and validity of the program simultaneously.
Above content is to combine specific case further description made for the present invention, it is impossible to assert that the present invention's is specific
Embodiment is only limitted to this, for general technical staff of the technical field of the invention, is not departing from present inventive concept
On the premise of, some simple deduction or replace can also be made, the claim that the present invention is submitted should be all considered as belonging to
The scope of patent protection that book is determined.
Claims (4)
1. the mains frequency quick determination method of a kind of high accuracy and anti-noise jamming, it is characterised in that：Including synchronized phase
Position open loop detection, beat frequency phase calculate link and frequency closed loop detection, by the mains voltage signal detected
The locking phase of power network can be obtained in real time through synchronized phase open loop detection, and link is calculated by beat frequency phase
Extract the beat frequency phase in synchronized phase, and by beat frequency phase information incoming frequency closed loop detection to obtain power network
Real-time frequency.
2. a kind of high-precision and jamproof mains frequency quick determination method as claimed in claim 1, it is characterised in that
Described synchronized phase open loop detection comprises the following steps：
（1）Pass through voltage sensor senses mains voltage signalU a、U b、U c；
（2）By the mains voltage signal detectedU a、U b、U cRotational coordinates is synchronized by synchronous rotating angle module
Conversion, obtains the voltage signal under two-phase rotating coordinate systemU d 、U q ；
（3）If there are high-frequency noise or harmonic components in the mains voltage signal collected, need in synchronously rotating reference frame
Increase filter module after conversion module, the output signal in step (2) is filtered, to eliminate the shadow of noise, harmonic wave
Ring；
（4）Obtained according to step (3)U d、U q, select correct by Rule of judgmentθ ex, Rule of judgment is as follows：IfU d>0 andU q>
0, thenθ ex=0；IfU d<0, thenθ ex=π；IfU d>0 andU q<0, thenθ ex=2π；
（5）The parameter obtained according to step (3), (4)U d 、U q 、θ ex , the real-time width of line voltage is calculated with reference to amplitude, phase formula
Value and phase；Wherein, amplitude calculation formula is：, phase calculation formula is：；
Wherein,ω s tAs operating frequency phase；arctan(U q/U d)+θ exAs beat frequency phase.
3. a kind of high-precision and jamproof mains frequency quick determination method as claimed in claim 1, it is characterised in that
Described beat frequency phase calculates link and comprised the following steps：
（1）The beat frequency phase extracted is designated asx, being postponed a sampling period is designated asy, by cycle rate counternInitial value set
It is set to 0；
（2）ComparexWithySize, if (y-x) it is more than threshold value M（The M π of theoretical value 2, it is contemplated that caused by discrete sampling process
Error, M value, which should take, is slightly less than 2 π, and the sampling period is bigger, and threshold value should be smaller）, then cycle rate counternIt is otherwise not right from increasing 1nAdded up, export continuous phase information and be designated as phase, wherein phase=x+2*π*n。
4. the mains frequency quick determination method of a kind of high accuracy as claimed in claim 1 and anti-noise jamming, its feature
It is, described frequency closed loop detection comprises the following steps：
（1）Output phase one sampling period of delay that beat frequency phase is calculated into link is designated asθ；
（2）By step（1）OutputθThe input signal adjusted as closed loop, feedback is used as after the output of closed loop regulation is integrated
Signalθ feedback, itself divided by 2 π obtain difference frequency Δ by the output signal that both differences are adjusted after being adjusted through PI as closed loopf；
（3）By difference frequency ΔfThe actual frequency that can obtain power network is superimposed with power frequency (China is 50Hz)f。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710437135.8A CN107271772B (en) | 2017-06-12 | 2017-06-12 | A kind of mains frequency rapid detection method of high-precision and anti-noise jamming |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710437135.8A CN107271772B (en) | 2017-06-12 | 2017-06-12 | A kind of mains frequency rapid detection method of high-precision and anti-noise jamming |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107271772A true CN107271772A (en) | 2017-10-20 |
| CN107271772B CN107271772B (en) | 2019-06-25 |
Family
ID=60066263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710437135.8A Expired - Fee Related CN107271772B (en) | 2017-06-12 | 2017-06-12 | A kind of mains frequency rapid detection method of high-precision and anti-noise jamming |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107271772B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110308326A (en) * | 2019-07-15 | 2019-10-08 | 国网山西省电力公司电力科学研究院 | A method of open loop can be improved and surveys phase algorithm noiseproof feature |
| CN110412348A (en) * | 2018-04-27 | 2019-11-05 | 精工爱普生株式会社 | Count value generative circuit, physical quantity transducer module and works monitoring arrangement |
| CN112151065A (en) * | 2019-06-28 | 2020-12-29 | 力同科技股份有限公司 | Method, device and equipment for detecting single tone signal frequency and computer storage medium |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10170563A (en) * | 1996-12-05 | 1998-06-26 | Mitsubishi Electric Corp | Frequency detection device |
| JP2010266411A (en) * | 2009-05-18 | 2010-11-25 | Mitsubishi Electric Corp | Synchronous phasor measuring device |
| CN102136716A (en) * | 2010-09-08 | 2011-07-27 | 上海岩芯电子科技有限公司 | Grid frequency detection method based on phase locked loop technology |
| CN104280610A (en) * | 2014-10-10 | 2015-01-14 | 深圳晶福源科技股份有限公司 | Phase-lock loop and grid frequency detecting method of phase-lock loop |
| CN104868909A (en) * | 2015-06-01 | 2015-08-26 | 合肥工业大学 | Floating frequency and phase lock loop based on voltage quadrature resonator (QR) and measuring method thereof |
| CN106018959A (en) * | 2016-06-23 | 2016-10-12 | 国网浙江省电力公司绍兴供电公司 | Frequency observation method for droop control of grid-connected inverter |
| CN205643513U (en) * | 2016-03-02 | 2016-10-12 | 安徽理工大学 | System for accurate unbalanced three phase output frequence that detects |
-
2017
- 2017-06-12 CN CN201710437135.8A patent/CN107271772B/en not_active Expired - Fee Related
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10170563A (en) * | 1996-12-05 | 1998-06-26 | Mitsubishi Electric Corp | Frequency detection device |
| JP2010266411A (en) * | 2009-05-18 | 2010-11-25 | Mitsubishi Electric Corp | Synchronous phasor measuring device |
| CN102136716A (en) * | 2010-09-08 | 2011-07-27 | 上海岩芯电子科技有限公司 | Grid frequency detection method based on phase locked loop technology |
| CN104280610A (en) * | 2014-10-10 | 2015-01-14 | 深圳晶福源科技股份有限公司 | Phase-lock loop and grid frequency detecting method of phase-lock loop |
| CN104868909A (en) * | 2015-06-01 | 2015-08-26 | 合肥工业大学 | Floating frequency and phase lock loop based on voltage quadrature resonator (QR) and measuring method thereof |
| CN205643513U (en) * | 2016-03-02 | 2016-10-12 | 安徽理工大学 | System for accurate unbalanced three phase output frequence that detects |
| CN106018959A (en) * | 2016-06-23 | 2016-10-12 | 国网浙江省电力公司绍兴供电公司 | Frequency observation method for droop control of grid-connected inverter |
Non-Patent Citations (1)
| Title |
|---|
| 熊连松等: "不对称电网同步相位的快速开环捕获方法研究", 《中国电机工程学报》 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110412348A (en) * | 2018-04-27 | 2019-11-05 | 精工爱普生株式会社 | Count value generative circuit, physical quantity transducer module and works monitoring arrangement |
| CN110412348B (en) * | 2018-04-27 | 2024-01-09 | 精工爱普生株式会社 | Count value generation circuit, physical quantity sensor module, and structure monitoring device |
| CN112151065A (en) * | 2019-06-28 | 2020-12-29 | 力同科技股份有限公司 | Method, device and equipment for detecting single tone signal frequency and computer storage medium |
| CN112151065B (en) * | 2019-06-28 | 2024-03-15 | 力同科技股份有限公司 | Method, device, equipment and computer storage medium for detecting single-tone signal frequency |
| CN110308326A (en) * | 2019-07-15 | 2019-10-08 | 国网山西省电力公司电力科学研究院 | A method of open loop can be improved and surveys phase algorithm noiseproof feature |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107271772B (en) | 2019-06-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102305886B (en) | Fundamental voltage synchronous signal detection method during harmonic distortion and unbalance of network voltage | |
| CN107453401B (en) | Doubly-fed wind generator parameter identification method | |
| CN107706929B (en) | Minimum variance filtering-based adaptive phase-locked loop method and system | |
| CN107045082A (en) | The synchronized phase open loop detection method of high accuracy and anti-noise jamming | |
| CN102868183B (en) | Sliding-mode variable structure control method of single phase grid-connected inverter based on multi-resonant sliding mode surface | |
| CN108761222A (en) | It is a kind of imbalance operating mode under network voltage order components quick extraction system and method | |
| CN107271772B (en) | A kind of mains frequency rapid detection method of high-precision and anti-noise jamming | |
| CN105158592B (en) | Three phase network impedance real-time detection method under power network asymmetrical | |
| CN104597320B (en) | A kind of method calculated suitable for multiple frequency alternating current signals | |
| WO2022226709A1 (en) | Power control-based method for analyzing stability of permanent magnet synchronous fan accessing weak grid | |
| CN102401858A (en) | Method for detecting fundamental component and harmonic component of voltage of power grid | |
| CN104360137B (en) | A kind of electric voltage temporary drop detecting method suitable for dynamic electric voltage recovery device | |
| CN103278686B (en) | A kind of frequency analysis filtering system and intelligent selection harmonic detecting method | |
| CN105116195B (en) | Suitable for the big method for detecting voltage drop of Voltage Harmonic content | |
| CN102221639A (en) | Positive and negative sequence current real-time detection method | |
| CN105785788A (en) | Rapid three-phase voltage phase-locked loop method and dynamic response performance analyzing method thereof | |
| CN103094924A (en) | Method and device for obtaining power grid synchronic benchmark sine based on absence of phase lock loop | |
| WO2023071672A1 (en) | Rapid and precise power grid information sensing method based on nonlinear robust estimation | |
| CN110417056A (en) | The device level oscillation source localization method and its device of double-fed blower grid-connected system | |
| CN104502707A (en) | Synchronized phasor measurement method for electrical power system based on cubic spline interpolation | |
| CN105021872A (en) | Active and passive component detection method for different current components in distorted and asymmetric voltage state of electrical network | |
| CN108414838B (en) | Method for measuring line impedance of inverter parallel system | |
| CN102062803A (en) | Active current extraction method based on orthogonal sine wave integral modulation | |
| CN101504442B (en) | Real-time detection method for double-SRF dual-feedback aerogenerator rotor current positive and negative components | |
| CN107796977A (en) | A kind of three-phase power grid voltage parameter detection method and device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20190625 Termination date: 20200612 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |