CN105353214A - Improved harmonic detection method - Google Patents
Improved harmonic detection method Download PDFInfo
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- CN105353214A CN105353214A CN201510976206.2A CN201510976206A CN105353214A CN 105353214 A CN105353214 A CN 105353214A CN 201510976206 A CN201510976206 A CN 201510976206A CN 105353214 A CN105353214 A CN 105353214A
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- phase
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/16—Spectrum analysis; Fourier analysis
Abstract
The invention relates to an improved harmonic detection method. The improved harmonic detection method comprises the following steps: whether network voltage has distortion is detected; when the distortion is detected, the detected distortion is preprocessed; the voltage is sampled; an obtained square signal which is synchronous with the network voltage is taken as input of a phase detector; a lowpass filter and a function generator constitute a PLL (phase-locked loop) circuit through the phase detector. According to the method, distortion detection of the network voltage and preprocessing are performed through a sensor and a DSP (digital signal processor) before a traditional voltage sampling link for detecting voltage phase information through PLL, so that the problem that fundamental positive-sequence active current cannot be obtained accurately due to the fact that the phase detected by the PLL is not the phase of voltage positive-sequence components when the power voltage has distortion is solved.
Description
Technical field
The present invention relates to Harmonic Detection and active reactive current processing, relate to the stability of microgrid, be specifically related to a kind of harmonic detecting method of improvement.
Background technology
Along with the proposition of micro-capacitance sensor concept, the fast development of Distributed Power Generation, traditional electric system is had very large change, electric system becomes more complicated, has meanwhile had higher requirement to the quality of power supply of electrical network.Usually detected by the harmonic wave of ip-iq detection method to electrical network, thus obtain instantaneous active electric current and instantaneous reactive current.Ip-iq detection method is actually the differentiation of p-q detection method and comes, this method needs the phase information obtaining line voltage, corresponding sinusoidal signal sin ω t and cosine signal-cos ω t is calculated according to phase information, here the acquisition of phase place is obtained by phaselocked loop exactly, according to instantaneous reactive power theory, instantaneous active ip can be calculated, instantaneous reactive iq, ip, iq can obtain their DC component after low-pass filter filtering, here DC component has three-phase fundamental current to produce, therefore inverse transformation is carried out to DC component and can calculate three-phase fundamental current, three-phase current deducts three-phase fundamental current just can obtain harmonic current, thus reach the object detecting harmonic wave.But there is line voltage aberration problems when utilizing PLL phaselocked loop to obtain electric network voltage phase information, if line voltage distorts, phase place voltage positive-sequence component being detected that phaselocked loop just can not be correct, therefore just can not accurately obtain fundamental positive sequence active current.
In sum, there is following technical matters in prior art: along with a large amount of uses of the non-linear converter plants such as power electronics, bring serious harmonic pollution to some Force system, cause very large electric energy loss, threaten the stable operation of electrical network.Therefore effective check processing must be carried out to harmonic wave.
Summary of the invention
The object of the present invention is to provide a kind of harmonic detecting method of improvement, solve when its voltage phase information of detection that distortion phaselocked loop can not be correct occurs line voltage, thus cause can not accurately obtaining fundamental active current.
When line voltage exists distortion, requirement can obtain fundamental positive sequence active current accurately, and for above above-mentioned prior art problem and goal of the invention, the present invention proposes a kind of harmonic detecting method of improvement, comprises the steps:
(1) whether network voltage detection exists distortion phenomenon;
(2) when distortion phenomenon being detected, pre-service is carried out to the distortion phenomenon detected;
(3) voltage is sampled;
(4) square-wave signal synchronous with line voltage obtained in step (3), as the input of phase detector;
(5) by phase detector, low-pass filtering sum functions generator forms a phase-locked loop circuit.
Further, in step (1), line voltage carries out the detection of distortion phenomenon by sensor and dsp processor.
Further, when loop-locking, sine wave output is synchronous with line voltage.
Further, in step (1), adopt the harmonic current of instantaneous reactive power theory, reactive current (ip-iq) detection method or p-q detection method, complete the check processing to harmonic wave.
Further, in step (3), voltage sampling just goes PLL phaselocked loop to detect voltage phase information.
Further, the ip-iq detection method calculating instantaneous active electric current and instantaneous reactive current iq comprises the steps:
A. the phase information of line voltage is gathered;
B. calculate corresponding sinusoidal signal sin ω t cosine signal-cos ω t according to phase information, phase information can have phaselocked loop to obtain;
C. instantaneous active ip is calculated, instantaneous reactive iq,
D.ip, iq obtain their DC component after low-pass filter filtering
E. the fundamental current i of shape shadow is calculated
af, i
bf, i
cf;
F. three-phase current deducts a few ripple electric current of three-phase and obtains three phase harmonic current i
af, i
bh, i
ch.
Further, detected by the harmonic wave of ip-iq detection method to electrical network, thus obtain instantaneous active electric current and instantaneous reactive current.
Further, p-q detection method comprises the steps:
1) phase information of line voltage is obtained;
2) corresponding sinusoidal signal sin ω t and cosine signal-cos ω t is calculated according to phase information;
3) instantaneous active ip, instantaneous reactive iq is calculated;
4) ip, iq obtain their DC component after low-pass filter filtering;
5) three-phase fundamental current is calculated;
6) three-phase current deducts three-phase fundamental current and obtains harmonic current, thus reaches the object detecting harmonic wave.
Further, in steps d
be produced by three-phase fundamental current, calculate through inverse transformation in step e.
Further, step 1) in phase place obtained by phaselocked loop, step 3) in calculate according to instantaneous reactive power theory, step 4) in DC component have three-phase fundamental current to produce, step 5) in inverse transformation carried out to DC component calculate three-phase fundamental current.
Compared with currently available technology, the present invention carries out Distortion Detect by sensor and DSP to line voltage and then carries out pre-service before conventional P LL phaselocked loop detects the voltage sampling link of voltage phase information, and then solve when supply voltage exist distort time, the phase place that phaselocked loop detects is not the phase place of voltage positive-sequence component and causes can not accurately obtaining the problem of fundamental positive sequence active current.
Accompanying drawing explanation
Fig. 1 is the solution of the present invention process flow diagram.
Fig. 2 is ip-iq harmonic detecting method schematic diagram.
Embodiment
Describe the present invention with reference to the accompanying drawings below, it is a kind of preferred embodiment in numerous embodiments of the present invention.
With reference to Fig. 1, in a preferred embodiment, line voltage detects whether there is distortion phenomenon by sensor and dsp processor, and pre-service is carried out to the distortion phenomenon detected, then voltage is sampled, obtain the square-wave signal synchronous with line voltage, as the input of phase detector.By phase detector, low-pass filtering sum functions generator forms a phase-locked loop circuit.When loop-locking, sine wave output is synchronous with line voltage.Preferably by the harmonic detecting method of ip-iq detection method and instantaneous reactive power theory, complete the check processing to harmonic wave.
Harmonic current based on instantaneous reactive power theory, the detection method of reactive current have two kinds: a kind of is the p-q method calculating instantaneous active power p and instantaneous reactive power q, and another kind is the ip-iq method calculating instantaneous active electric current and instantaneous reactive current iq.Ip-iq Harmonic detection is actual is a kind of method derived from by p-q detection method.Fig. 2 is the theory diagram of ip-iq harmonic detecting method, and this method needs the phase information using line voltage, and calculate corresponding sinusoidal signal sin ω t cosine signal-cos ω t according to phase information, phase information can have phaselocked loop to obtain.According to instantaneous reactive power theory, can calculate instantaneous active ip, instantaneous reactive iq, ip, iq can obtain their DC component after low-pass filter filtering
here
produced by three-phase fundamental current, therefore they are through inverse transformation, can calculate the fundamental current i of shape shadow
af, i
bf, i
cf, three-phase current deducts a few ripple electric current of three-phase just can obtain three phase harmonic current i
af, i
bh, i
ch.
Detected by the harmonic wave of ip-iq detection method to electrical network, thus obtain instantaneous active electric current and instantaneous reactive current.Ip-iq detection method is actually the differentiation of p-q detection method and comes, this method needs the phase information obtaining line voltage, corresponding sinusoidal signal sin ω t and cosine signal-cos ω t is calculated according to phase information, here the acquisition of phase place is obtained by phaselocked loop exactly, according to instantaneous reactive power theory, instantaneous active ip can be calculated, instantaneous reactive iq, ip, iq can obtain their DC component after low-pass filter filtering, here DC component has three-phase fundamental current to produce, therefore inverse transformation is carried out to DC component and can calculate three-phase fundamental current, three-phase current deducts three-phase fundamental current just can obtain harmonic current, thus reach the object detecting harmonic wave.Here pass through dsp processor by sensor detection of grid voltage, obtain mains voltage signal and whether distort, if there is distortion will carry out pre-service to line voltage, obtain the square-wave signal synchronous with line voltage, as the input of phase detector.By phase detector, low-pass filtering sum functions generator forms a phase-locked loop circuit.When loop-locking, sine wave output is synchronous with line voltage.
Above by reference to the accompanying drawings to invention has been exemplary description; obvious specific implementation of the present invention is not subject to the restrictions described above; as long as have employed the various improvement that method of the present invention is conceived and technical scheme is carried out; or directly apply to other occasion, all within protection scope of the present invention without improving.
Claims (10)
1. the harmonic detecting method improved, is characterized in that, comprise the steps:
(1) whether network voltage detection exists distortion phenomenon;
(2) when distortion phenomenon being detected, pre-service is carried out to the distortion phenomenon detected;
(3) voltage is sampled;
(4) square-wave signal synchronous with line voltage obtained in step (3), as the input of phase detector;
(5) by phase detector, low-pass filtering sum functions generator forms a phase-locked loop circuit.
2. the harmonic detecting method improved as claimed in claim 1, it is characterized in that, in step (1), line voltage carries out the detection of distortion phenomenon by sensor and dsp processor.
3. the harmonic detecting method of the improvement as described in claim 1 and 2, is characterized in that, when loop-locking, sine wave output is synchronous with line voltage.
4. the harmonic detecting method of the improvement according to any one of claim 1-3, it is characterized in that, in step (1), adopt the harmonic current of instantaneous reactive power theory, reactive current (ip-iq) detection method or p-q detection method, complete the check processing to harmonic wave.
5. the harmonic detecting method of the improvement according to any one of claim 1-4, is characterized in that, in step (3), voltage sampling just goes PLL phaselocked loop to detect voltage phase information.
6. the harmonic detecting method improved as claimed in claim 4, is characterized in that, the ip-iq detection method calculating instantaneous active electric current and instantaneous reactive current iq comprises the steps:
A. the phase information of line voltage is gathered;
B. calculate corresponding sinusoidal signal sin ω t cosine signal-cos ω t according to phase information, phase information can have phaselocked loop to obtain;
C. instantaneous active ip is calculated, instantaneous reactive iq,
D.ip, iq obtain their DC component after low-pass filter filtering
E. the fundamental current i of shape shadow is calculated
af, i
bf, i
cf;
F. three-phase current deducts a few ripple electric current of three-phase and obtains three phase harmonic current i
af, i
bh, i
ch.
7. the harmonic detecting method of the improvement as described in claim 4 and 6, is characterized in that, is detected by the harmonic wave of ip-iq detection method to electrical network, thus obtains instantaneous active electric current and instantaneous reactive current.
8. the harmonic detecting method improved as claimed in claim 4, it is characterized in that, p-q detection method comprises the steps:
1) phase information of line voltage is obtained;
2) corresponding sinusoidal signal sin ω t and cosine signal-cos ω t is calculated according to phase information;
3) instantaneous active ip, instantaneous reactive iq is calculated;
4) ip, iq obtain their DC component after low-pass filter filtering;
5) three-phase fundamental current is calculated;
6) three-phase current deducts three-phase fundamental current and obtains harmonic current, thus reaches the object detecting harmonic wave.
9. the harmonic detecting method of the improvement as described in claim 6 and 7, is characterized in that, in steps d
be produced by three-phase fundamental current, calculate through inverse transformation in step e.
10. the as claimed in claim 8 harmonic detecting method improved, is characterized in that, step 1) in phase place obtained by phaselocked loop,
Step 3) according to instantaneous reactive power theory calculate, step 4) in DC component have three-phase fundamental current to produce,
Step 5) in inverse transformation carried out to DC component calculate three-phase fundamental current.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110531138A (en) * | 2019-07-08 | 2019-12-03 | 江苏科技大学 | A kind of Active Power Filter Harmonic Currents detection method |
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| CN1079308A (en) * | 1992-05-23 | 1993-12-08 | 贺守正 | Method for monitoring harmonic wave of electric power with robot calculator |
| CN1611953A (en) * | 2003-10-27 | 2005-05-04 | 贺守正 | Method for measuring factory harmonic wave and measuring instrument |
| US7605997B2 (en) * | 2007-02-05 | 2009-10-20 | Fujitsu Limited | Head-gap calculating device, storage device, head-gap calculating method, and computer product |
| JP4883350B2 (en) * | 2006-06-29 | 2012-02-22 | アイシン精機株式会社 | Terahertz wave generator / detector |
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2015
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Patent Citations (5)
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|---|---|---|---|---|
| CN2126486U (en) * | 1992-05-07 | 1992-12-30 | 东南大学 | Harmonic factor testing apparatus for intelligence-power telephone |
| CN1079308A (en) * | 1992-05-23 | 1993-12-08 | 贺守正 | Method for monitoring harmonic wave of electric power with robot calculator |
| CN1611953A (en) * | 2003-10-27 | 2005-05-04 | 贺守正 | Method for measuring factory harmonic wave and measuring instrument |
| JP4883350B2 (en) * | 2006-06-29 | 2012-02-22 | アイシン精機株式会社 | Terahertz wave generator / detector |
| US7605997B2 (en) * | 2007-02-05 | 2009-10-20 | Fujitsu Limited | Head-gap calculating device, storage device, head-gap calculating method, and computer product |
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Application publication date: 20160224 |