CN107870285A - Grid voltage sags fast algorithm of detecting based on phase offset - Google Patents
Grid voltage sags fast algorithm of detecting based on phase offset Download PDFInfo
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- CN107870285A CN107870285A CN201610859477.4A CN201610859477A CN107870285A CN 107870285 A CN107870285 A CN 107870285A CN 201610859477 A CN201610859477 A CN 201610859477A CN 107870285 A CN107870285 A CN 107870285A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
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Abstract
The invention discloses a kind of grid voltage sags fast algorithm of detecting based on phase offset, utilize single order all-pass filter phase delay algorithm, the algorithm is by realizing 90 degree of phase delays, and then the cosine amount that new symmetrical voltage occurs that constructs can be calculated, conventional dq algorithms can be utilized quickly to judge that grid voltage three-phase asymmetrical voltage falls on this basis, this method examines high sensitivity, speed is fast, detection arbitration functions are all realized by software, securely and reliably, simplify design cycle, reduce design cost, no matter symmetrically fall for three-phase voltage, or any one phase or two-phase can quickly judge, it is versatile, flexible design.
Description
Technical field
The present invention relates to distribution and power control technology field, is calculated more particularly to a kind of grid voltage sags quick detection
Method.
Background technology
1. technical background：
Grid voltage sags and power failure are than more serious power quality problem[1], power network once breaks down, right
Power grid enterprises and user can cause very big loss.Fast and accurately detect line voltage falls failure, is that equipment is carried out
Protect the precondition of control.In some important application scenarios, when Voltage Drop failure occurs, it need to be quickly switched into and answer urgent telegram
Source or timely shut-off equipment are protected.And it is that equipment carries out protection act fast and accurately to detect grid voltage sags failure
Precondition.For grid voltage three-phase symmetrical falls, conventional dq algorithms disclosure satisfy that quick judgement demand, but for three
Phase asymmetry is fallen just inapplicable.Article proposes on the basis of the three-phase symmetric voltage method new using phase voltage construction is fallen
It is a kind of to utilize single order all-pass filter phase delay algorithm, by realizing 90 degree of phase delays, and then construction can be calculated
The cosine amount that new symmetrical voltage occurs, conventional dq algorithms can be utilized quickly to judge grid voltage three-phase not on this basis
Symmetrical voltage falls.Simulation analysis result shows that the algorithm accuracy of detection is high, and real-time is good.
2. the prior art directly related with the present invention：
Algorithm at present on grid voltage sags detection is a lot, and conventional Voltage Drop algorithm includes：Conventional dq conversion
Method[2-4], α β change detection algorithms[5-7], virtual value calculating method.
The content of 2.1 prior arts one
Conventional dq converter techniques
For symmetrical three-phase power grid voltage, line voltage only has positive-sequence component and zero-sequence component.Conventional at present is conventional
The dq converter techniques based on three-phase symmetrical, if symmetrical three-phase voltage is
The relational expression that abc three-phase voltages are transformed to dq coordinate systems is
[Ud, Uq]T=C [ua, ub, uc]T (2)
C is the three phase static left side to two-phase rotating coordinate transformation matrix in above formula
Voltage after dq is converted
The d shaft voltages of progress dq conversion gained direct to voltage are a DC quantities (such as Fig. 1), and ABC three-phase voltages are in 0.2S
When bust to the 20% of rated value, recover corresponding Ud values to 0.4S；When three-phase power grid voltage asymmetry, line voltage can be present
Of ac (such as Fig. 2), ABC three-phases be present in negative sequence component and zero-sequence component, the d shaft voltages of progress dq conversion gained direct to voltage
A phases bust in 0.2S to the 20% of rated value, recovers corresponding Ud values to 0.4S in voltage.
The shortcomings that 2.2 prior art one
The dq of conventional three-phase voltage is converted when three-phase voltage balances, and it is its crest voltage that can calculate Ud, Uq 0,
The program judges that Voltage Drop is more effective when symmetrical to ABC three-phase voltages, but single-phase voltage is fallen or two-phase voltage is fallen
When just no longer be applicable, when imbalance of three-phase voltage, there is negative phase-sequence and zero-sequence component in line voltage, and dq changes are directly carried out to voltage
Change, Ud voltages have of ac, and inverter can not fast and accurately judge Voltage Drop according to the change of Ud voltages.
The content of 2.3 prior arts two
During for Voltage Drop, conventional virtual value judges, crest voltage judges and α β change detection algorithms.
The shortcomings that 2.4 prior art two
Conventional virtual value judges that crest voltage judges to need the sampled data with a cycle (or half period) to carry out
Judge, larger delay be present[8], real-time is bad；α β change detections algorithms at the Voltage Drop moment due to there may be high frequency
Harmonic components, influence accuracy of detection.
The content of the invention
In order to overcome the above-mentioned deficiencies of the prior art, the invention provides a kind of grid voltage sags based on phase offset
Fast algorithm of detecting.The present invention can effectively overcome the shortcomings of existing scheme, while implementation is simple, it is not necessary to increase additionally into
This.
The technical problems to be solved by the invention be mainly power network occur falling process in quick detection go out voltage change, it is right
Fall or two-phase falls and three-phase falls and can quickly detected in single-phase.
The technical solution adopted in the present invention is：Fall the deficiency that can not be judged to single-phase for traditional scheme, give
A kind of detection sensitivity is high, and corresponding speed is fast, the Voltage Drop detection algorithm of strong applicability.
In the algorithm such as Fig. 3, the respective new balanced three-phase voltage of A, B, C phase voltage construction is taken respectively, then by each
From phase offset after can construct respectively on the basis of A, B, C phase voltage corresponding to three groups of new balanced three-phase voltages,
By taking A phase voltages as an example, if the symmetrical three-phase voltage constructed is respectively Uasa, Uasb, Uasc, this three-phase voltage becomes by dq
It is Uda that change, which calculates d shaft voltages, thus can fast and accurately detect that A phase voltages are fallen.
Equally by taking B phase voltages as an example, if the symmetrical three-phase voltage constructed is respectively Ubsa, Ubsb, Ubsc, this three-phase
It is Udb that voltage calculates d shaft voltages by dq changes, thus can fast and accurately detect that B phase voltages are fallen.
By taking C phase voltages as an example, if the symmetrical three-phase voltage constructed is respectively Ucsa, Ucsb, Ucsc, this three-phase voltage
It is Udc to calculate d shaft voltages by dq changes, thus can fast and accurately detect that c phase voltages are fallen.
In above-mentioned algorithm, either three-phase falls, and still wherein any one phase is fallen, and can fast and accurately judge electricity
Pressure is fallen, and ensures that equipment is acted in time.
From upper section background technology, when asymmetrical three-phase falls, of ac be present inside d shaft voltages, system can not
Fast and accurately Voltage Drop is judged according to the change of d shaft voltages, therefore structure can be come by using the voltage for falling phase
New balanced three-phase voltage is made, is then passing through dq computings, so can be obtained by stable d shaft voltages, so as to three-phase not
Symmetrical voltage carries out falling detection judgement.If it is A phase voltages are fallen, because A phase voltages are
Ua=U sin (wt) (5)
Then constructing B on the basis of A phase voltages, C two-phase voltages, if posttectonic A, B, C three-phase voltages are Uasa, Uasb,
Uasc then has
Uasa=ua=U sin (wt) (6)
The virtual three-phase system that A phase voltages can construct according to (6) (7) (8) formula, as long as now Uasb, Uasc values
Calculate can using the dq computings progress Voltage Drop of routine to judge, from (7) and (8), as long as U therein
Cos (wt) is obtained.
A coefficient is multiplied by because cos (wt) is sin (wt) derivative, conventional way [4] is to utilize discrete numeral
Amount seeks difference to replace derivative, but this precision of method is not high, therefore we can obtain cos (wt) by phase offset.
From mathematics triangle formula：
Therefore, (7), (8) can be changed to following form
Wherein ua is actual A phase voltages, ua90For the value of A phase voltage quadrature laggings, as long as obtaining ua90It can obtain
Uasb, Uasc.Understand that single order all pass circuit can produce fixed phase delay by mould electricity knowledge, by joining to single order all pass circuit
Several selections, makes the phase delay of 90 degree of generation, and Fig. 4 is single order all-pass wave filtering circuit theory diagrams.
90 degree of phase delays are realized, take R1=R2, then can be obtained
It is so as to release its transmission function
Wherein, f=50Hz
Above transmission function discretization can be obtained
Can obtain difference equation by (13) formula is
Y (k)=0.98425*y (k-1)+u (k-1) -0.98425u (k) (14)
The function of single order all-pass digital filter, phase delay 90 can be achieved by C language by difference equation above
Degree.Fig. 5 is waveform before and after phase delay, as can be seen from the figure realizes 90 degree of phase delay.
Phase offset Voltage Drop quick judgment method is emulated using Matlab7.8.0, such as Fig. 6.
If phase voltage virtual value is 220V in simulations, frequency 50Hz, in 0.2~0.4S, A phase voltages drop into volume
20%, Fig. 7 of tentering value is asymmetrical three-phase Voltage Drop figure, is followed successively by three-phase voltage from top to bottom, and A phase voltages construction is virtual
Three-phase system d shaft voltages are Uda, and it is Udb that B phase voltages, which construct virtual three-phase system d shaft voltages, and C phase voltages construct virtual three-phase
System d shaft voltages are Udc, it can be seen that when generation asymmetrical voltage falls, can be according to Uda, Udb, Udc values
The voltage for judging to fall is judged.
As seen from Figure 8, fall from A phase voltages by 1/4 sinusoidal cycles it may determine that out falling, the time exists
It can determine and after 5mS.
Compared with prior art, the beneficial effects of the invention are as follows utilize voltage and then construction three on the basis of one phase voltage of selection
Phase equalizing voltage, this method examine high sensitivity, and speed is fast, and detection arbitration functions are all realized by software, quick action, peace
It is complete reliable, design cycle is simplified, reduces design cost, can be used for different capacity grade equipment, to different type
Voltage Drop can use, versatile, flexible design.
The algorithm has high sensitivity, faster response speed, is supplied power with double circuit suitable for intelligent power distribution and quickly judges electricity
Pressure, which is fallen, carries out timely action processing to select high-quality power supply；Strong applicability, either three-phase voltage are fallen simultaneously, also
It is that any one phase or two-phase can quickly judge；Realized completely by software, it is not necessary to any hardware circuit, good economy performance, side
Just it is easily modified.
Brief description of the drawings
Fig. 1 converts for balanced three-phase voltage dq；
Fig. 2 is that single-phase voltage falls Ud waveforms；
Fig. 3 is to judge block diagram based on phase offset Voltage Drop；
Fig. 4 is single order all-pass filter circuit；
Fig. 5 is single order numeral all-pass wave filtering design sketch；
Fig. 6 is phase offset Voltage Drop detection algorithm analogous diagram；
Fig. 7 is that asymmetrical three-phase Voltage Drop judges analogous diagram；
Fig. 8 is A phase voltage drop-out time analogous diagrams.
Embodiment
Content described in this specification be the present invention preferable specific implementation case, the above case study on implementation side of being merely to illustrate
The technical scheme of case and the limitation of non-invention.All those skilled in the art's thinkings under this invention, by analysis, reasoning or have
Limit tests available technical scheme, all should be within the scope of the invention.
Claims (2)
- A kind of 1. grid voltage sags fast algorithm of detecting based on phase offset, it is characterised in that：Using falling phase voltage structure On the basis of making new three-phase symmetric voltage method, it is proposed that one kind utilizes single order all-pass filter phase delay algorithm, passes through reality Existing 90 degree of phase delays, and then the cosine amount that new symmetrical voltage occurs that constructs can be calculated, it can utilize on this basis Conventional dq algorithms quickly judge that grid voltage three-phase asymmetrical voltage falls.
- 2. the grid voltage sags fast algorithm of detecting according to claim 1 based on phase offset, it is characterised in that：Carry Gone out the algorithm that phase offset judges Voltage Drop, the algorithm using choose a phase voltage on the basis of voltage so that construct three-phase it is equal Weigh voltage, calculates the cosine amount occurred by phase offset, this method examines high sensitivity, and speed is fast, and detection arbitration functions are complete Portion is realized by software, securely and reliably, simplifies design cycle, is reduced design cost, no matter is symmetrically fallen for three-phase voltage, Or any one phase or two-phase can quickly judge, versatile, flexible design.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020128493A1 (en) * | 2018-12-20 | 2020-06-25 | Bowman Power Group Limited | Method and apparatus for identifying a grid fault |
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| CN102185330A (en) * | 2011-05-10 | 2011-09-14 | 中国电力科学研究院 | Device and method for compensating symmetrical voltages of power grid based on high-temperature superconducting energy storage |
| CN203732579U (en) * | 2013-12-20 | 2014-07-23 | 上海市质量监督检验技术研究院 | Voltage drop simulation generator used for measuring wind driven generator |
| CN104836503A (en) * | 2015-05-14 | 2015-08-12 | 贵州电网公司电力调度控制中心 | Double-feed wind power generator stator short circuit current calculating method under the condition of asymmetric faults |
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2016
- 2016-09-23 CN CN201610859477.4A patent/CN107870285A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102185330A (en) * | 2011-05-10 | 2011-09-14 | 中国电力科学研究院 | Device and method for compensating symmetrical voltages of power grid based on high-temperature superconducting energy storage |
| CN203732579U (en) * | 2013-12-20 | 2014-07-23 | 上海市质量监督检验技术研究院 | Voltage drop simulation generator used for measuring wind driven generator |
| CN104836503A (en) * | 2015-05-14 | 2015-08-12 | 贵州电网公司电力调度控制中心 | Double-feed wind power generator stator short circuit current calculating method under the condition of asymmetric faults |
Non-Patent Citations (2)
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| 罗劲松 等: "基于dq锁相环的改进型光伏电站并网点电压跌落检测方法研究", 《电测与仪表》 * |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020128493A1 (en) * | 2018-12-20 | 2020-06-25 | Bowman Power Group Limited | Method and apparatus for identifying a grid fault |
| US11867740B2 (en) | 2018-12-20 | 2024-01-09 | Bowman Power Group Limited | Method and apparatus for identifying a grid fault |
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Application publication date: 20180403 |