CN104734176A - Island detection method and device - Google Patents
Island detection method and device Download PDFInfo
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- CN104734176A CN104734176A CN201310724144.7A CN201310724144A CN104734176A CN 104734176 A CN104734176 A CN 104734176A CN 201310724144 A CN201310724144 A CN 201310724144A CN 104734176 A CN104734176 A CN 104734176A
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- 238000001514 detection method Methods 0.000 title claims abstract description 112
- 238000004364 calculation method Methods 0.000 claims abstract description 31
- 230000001360 synchronised effect Effects 0.000 claims abstract description 9
- 238000005070 sampling Methods 0.000 claims description 66
- 238000001914 filtration Methods 0.000 claims description 13
- 238000009825 accumulation Methods 0.000 claims description 9
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- H02J3/383—
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
- G01R25/005—Circuits for comparing several input signals and for indicating the result of this comparison, e.g. equal, different, greater, smaller, or for passing one of the input signals as output signal
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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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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Abstract
The invention discloses an island detection method and device. According to the method, a real time voltage angle is obtained according to power grid three-phase voltage calculation, a synchronous voltage angle is further determined according to a phase-locked loop based on the real time voltage angle; under normal circumstances, the real time voltage angle is approximately equal to the synchronous voltage angle; when an island and phase jump of grid point voltage occur, the real time voltage angle also changes suddenly with the phenomenon to enable a phase jump value to exist between the real time voltage angle and the synchronous voltage angle; if the average value of the voltage phase jump value of the grid point is larger than a preset jump threshold value in one circulation period, then the occurrence of the island is determined. The island detection method and device are simple in control process and convenient to achieve; the island can be detected in the one circulation detection period after occurrence, and therefore the detection efficiency is high; disturbance quantity is not needed to be added into the output of an inverter, and the output electric energy quality of the inverter can not be influenced; determination is conducted according to the average value of the phase jump, all interference factors are excluded, and the detection precision is improved; detection dead zones are reduced.
Description
Technical field
The application relates to grid monitoring techniques field, particularly relates to a kind of island detection method and device.
Background technology
Island effect, namely when the electric power system of Utilities Electric Co. quits work because of failure accident or the reasons such as maintenance that have a power failure, the grid-connected photovoltaic system being arranged on each user side fails to detect power down mode in time and rapidly self can not be cut off electricity network, causes the self-energizing island phenomenon cannot controlled by a kind of Utilities Electric Co. of grid-connected photovoltaic system load supplying towards periphery.Island effect may cause adverse influence to the equipment of whole power distribution system equipment and user side, as life security, the protection switch operation program etc. affected in distribution system of harm power equipment maintaining personnel; Therefore, island effect must be detected in time,
Endanger to avoid it.Conventional island detection method comprises initiatively islanding detect and passive islanding detect.
Initiatively islanding detect and control inverter, there is certain disturbance in the electric current making it export, frequency or phase place, when electrical network is normal, due to the balanced action of electrical network, can't detect these disturbances, when electrical network disconnects, the effect that these disturbances bring that inverter exports will accelerated accumulation, finally make voltage or frequency exceed allowed band, thus detect the generation of isolated island; Although this class methods accuracy of detection is high, control method is complicated, and the disturbance increased reduces the quality that inverter exports electric energy.
Passive islanding detect is namely according to inverter output end voltage during grid cut-off, and island effect detection is carried out in the change of frequency; There is larger check frequency in these class methods, as mistake/under-voltage and mistake/under-frequency detection method, when inverter with local load with its power output close to when mating, then the skew general of voltage and frequency is very little is even zero, cannot detect isolated island.
Summary of the invention
In view of this, the application's object is to provide a kind of island detection method and device, with under the prerequisite not reducing the quality of power supply, reduces the complexity of islanding detect, improves accuracy of detection.
For achieving the above object, the application provides following technical scheme:
A kind of island detection method, comprising:
Periodic samples is carried out to the three-phase voltage of grid-connected inverters point;
The real-time voltage angle θ of described also site in each sampling period is calculated according to described three-phase voltage;
Build a phase-locked loop based on described real-time voltage angle θ, and determine the synchronizing voltage angle Φ of described real-time voltage angle θ in each sampling period according to described phase-locked loop
avg;
Calculate described real-time voltage angle θ and synchronizing voltage angle Φ in each sampling period
avgdifference, obtain described in each sampling period and the phase hit value Ψ of site;
As described synchronizing voltage angle Φ
avgwhen being greater than 2 π, calculate the mean value Ψ of described phase hit value Ψ within a cycle detection cycle
avg;
If the mean value of described phase hit value is greater than default saltus step threshold value, then judge that isolated island occurs.
Preferably, describedly build a phase-locked loop based on described real-time voltage angle θ, comprising:
To the phase-locked angle Φ that described real-time voltage angle and described phase-locked loop export
plldifference carry out PI adjustment;
The output regulated according to described PI and electrical network nominal reference frequency ω
stepcalculate the frequency of phase locking ω of described phase-locked loop in each sampling period
pll;
To described frequency of phase locking ω
plladd up, obtain described phase-locked angle Φ
pll.
Preferably, the described synchronizing voltage angle Φ determining described real-time voltage angle θ in each sampling period according to described phase-locked loop
avg, comprising:
According to the mean value Ψ of described phase hit value in the upper cycle detection cycle
avgdetermine described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value and the mean value ω of described frequency of phase locking
avg;
At described synchronizing voltage angle Φ
avginitial value basis on, to the mean value ω of described frequency of phase locking
avgadd up, obtain described synchronizing voltage angle Φ
avg.
Preferably, the described mean value Ψ according to described phase hit value in the upper cycle detection cycle
avgdetermine described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value and the mean value ω of described frequency of phase locking
avg, comprising:
Judge the mean value Ψ of described phase hit value
avgabsolute value whether be greater than preset upgrade threshold value;
If so, then by the synchronizing voltage angle Φ in the upper cycle detection cycle
avgsubtract each other with 2 π, obtain described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value, and by the mean value ω of the frequency of phase locking in the upper cycle detection cycle
avgas the mean value ω of the frequency of phase locking in previous cycle sense cycle
avg;
If not, then by described phase-locked angle Φ
pllas synchronizing voltage angle Φ described in previous cycle sense cycle
avginitial value, and to described frequency of phase locking ω
pllin a power frequency period, carry out cumulative and average calculating operation, obtain the mean value ω of described frequency of phase locking
avg.
Preferably, described default renewal threshold value is 0.1 ~ 0.4 times of described default saltus step threshold value.
Preferably, the described real-time voltage angle θ calculating described also site in each sampling period according to described three-phase voltage, comprising:
Clarke coordinate transform is carried out to described three-phase voltage, obtains described grid-connected point voltage at the α axle component of two-phase rest frame and beta-axis component;
High-pass filtering is carried out, to filter DC component to described α axle component and beta-axis component;
The real-time voltage angle θ of described also site is calculated according to filtered described α axle component and beta-axis component.
A kind of isolated island detecting device, comprising:
Sampling unit, for carrying out periodic samples to the three-phase voltage of grid-connected inverters point;
Real-time voltage angle calculation unit, for calculating the real-time voltage angle θ of described also site in each sampling period according to described three-phase voltage;
Synchronizing voltage angle calculation unit, for building a phase-locked loop based on described real-time voltage angle θ, and determines the synchronizing voltage angle Φ of described real-time voltage angle θ in each sampling period according to described phase-locked loop
avg;
Phase hit value computing unit, for calculating described real-time voltage angle θ and synchronizing voltage angle Φ in each sampling period
avgdifference, obtain described in each sampling period and the phase hit value Ψ of site;
Phase hit average calculation unit, for working as described synchronizing voltage angle Φ
avgwhen being greater than 2 π, calculate the mean value Ψ of described phase hit value Ψ within a cycle detection cycle
avg;
Isolated island identifying unit, for judging whether the mean value of described phase hit value is greater than default saltus step threshold value, if so, then judges that isolated island occurs.
Preferably, described synchronizing voltage angle calculation unit comprises: phase-locked loop module and synchronous angle calculation module; Wherein,
Described phase-locked loop module comprises:
PI adjustment module, for the phase-locked angle Φ exported described real-time voltage angle and described phase-locked loop
plldifference carry out PI adjustment, and export PI regulate result;
Frequency of phase locking computing module, for regulating result and electrical network nominal reference frequency ω according to described PI
stepcalculate the frequency of phase locking ω of described phase-locked loop in each sampling period
pll;
Phase-locked angle computing module, for described frequency of phase locking ω
plladd up, obtain described phase-locked angle Φ
pll;
Described synchronous angle calculation module comprises:
Initial value determination module, for the mean value Ψ according to described phase hit value in the upper cycle detection cycle
avgdetermine described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value and the mean value ω of described frequency of phase locking
avg;
Accumulation calculating module, at described synchronizing voltage angle Φ
avginitial value basis on, to the mean value ω of described frequency of phase locking
avgadd up, obtain described synchronizing voltage angle Φ
avg.
Preferably, described initial value determination module comprises:
Upgrade judge module, for judging the mean value Ψ of described phase hit value
avgabsolute value whether be greater than preset upgrade threshold value;
First initial value determination module, for when the judged result of described first judge module is for being, by the synchronizing voltage angle Φ in the upper cycle detection cycle
avgsubtract each other with 2 π, obtain described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value, and by the mean value ω of the frequency of phase locking in the upper cycle detection cycle
avgas the mean value ω of the frequency of phase locking in previous cycle sense cycle
avg;
Second initial value determination module, for when the judged result of described first judge module is no, by described phase-locked angle Φ
pllas synchronizing voltage angle Φ described in previous cycle sense cycle
avginitial value, and to described frequency of phase locking ω
pllin a power frequency period, carry out cumulative and average calculating operation, obtain the mean value ω of described frequency of phase locking
avg.
Preferably, described real-time voltage angle calculation unit comprises:
Coordinate transformation module, for carrying out clarke coordinate transform to described three-phase voltage, obtains described grid-connected point voltage at the α axle component of two-phase rest frame and beta-axis component;
High-pass filtering module, for carrying out high-pass filtering, to filter DC component to described α axle component and beta-axis component;
Real-time angular computing module, for calculating the real-time voltage angle θ of described also site according to filtered described α axle component and beta-axis component.
As can be seen from above-mentioned technical scheme, the application, by the mean value of point voltage phase hit value grid-connected in the cycle detection cycle and default saltus step threshold value being compared, judges isolated island occurs when the mean value of described phase hit value is greater than described default saltus step threshold value; This island detection method control procedure is simple, is convenient to realize; Can detect in the cycle detection cycle after isolated island occurs, detection efficiency is high; Do not need the output to inverter to add disturbance quantity, can not have an impact to the output quality of power supply of inverter; Mean value according to phase hit judges, eliminates various disturbing factor, improves accuracy of detection; Reduce check frequency.Therefore, the embodiment of the present application solves the problem of prior art.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present application or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the application, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
The island detection method flow chart that Fig. 1 provides for the embodiment of the present application one;
The island detection method flow chart that Fig. 2 provides for the embodiment of the present application two;
Phase-locked loop schematic diagram in the island detection method that Fig. 3 provides for the embodiment of the present application;
The structured flowchart of the isolated island detecting device that Fig. 4 provides for the embodiment of the present application three;
The structured flowchart of the isolated island detecting device that Fig. 5 provides for the embodiment of the present application four;
The structured flowchart of synchronizing voltage angle calculation unit in the former checkout gear that Fig. 6 provides for the embodiment of the present application four.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present application, be clearly and completely described the technical scheme in the embodiment of the present application, obviously, described embodiment is only some embodiments of the present application, instead of whole embodiments.Based on the embodiment in the application, those of ordinary skill in the art are not making the every other embodiment obtained under creative work prerequisite, all belong to the scope of the application's protection.
The embodiment of the present application discloses a kind of island detection method and device, with under the prerequisite not reducing the quality of power supply, reduces the complexity of islanding detect, improves accuracy of detection.
With reference to Fig. 1, the island detection method that the embodiment of the present application one provides, comprises the steps:
S1, periodic samples is carried out to the three-phase voltage of grid-connected inverters point;
S2, calculate described in each sampling period and the real-time voltage angle θ of site according to described three-phase voltage;
The phase place of described real-time voltage angle θ and grid-connected point voltage.
S3, build a phase-locked loop based on described real-time voltage angle θ, and determine the synchronizing voltage angle Φ of described real-time voltage angle θ in each sampling period according to described phase-locked loop
avg;
Synchronizing voltage angle Φ
avgobtain based on the phase-locked loop of θ according to one; In stabilization of power grids situation, Φ
avgwith θ close to equal; When electric network voltage phase saltus step, due to the effect Φ of phase-locked loop
avgcan show as without line voltage angle in the same time in phase hit situation as far as possible.
S4, calculate described real-time voltage angle θ and synchronizing voltage angle Φ in each sampling period
avgdifference, obtain described in each sampling period and the phase hit value Ψ of site;
Phase hit value Ψ, namely under the interference of various factors, the virtual voltage angle θ of electrical network departs from fiducial value Φ
avgsize.
S5, as described synchronizing voltage angle Φ
avgwhen being greater than 2 π, calculate the mean value Ψ of described phase hit value Ψ within a cycle detection cycle
avg;
AC network phase place 2 π ft(f is mains frequency) change within the scope of 0 ~ 2 π, namely from Φ
avg=0 moment rose until Φ
avg=2 π, the time interval is a power frequency period, therefore can set and work as Φ
avgduring>=2 π, a cycle detection end cycle, and then start the mean value Ψ calculating phase hit value Ψ
avg.
If the mean value of S6 described phase hit value is greater than default saltus step threshold value, then judge that isolated island occurs.
The principle of above-mentioned island detection method is: the input of the described phase-locked loop based on real-time voltage angle θ inputs described real-time voltage angle θ, and output exports phase-locked angle Φ
plland feed back to input; Under normal circumstances, by this phase lock loop locks also record also site phase place, i.e. described synchronizing voltage angle Φ
avg; When the phase hit of isolated island generation, grid-connected point voltage, the real-time voltage angle θ that sampling obtains over time rule offsets, and makes the synchronizing voltage angle Φ of θ and locking
avgbetween there is a difference, i.e. phase hit value Ψ; If the mean value Ψ of the grid-connected point voltage phase hit value in the cycle detection cycle
avgbe greater than default saltus step threshold value, namely the phase hit of grid-connected point voltage is not the fortuitous phenomena in certain sampling period, but continues to occur within a cycle detection cycle, therefore judges that isolated island occurs; Otherwise, if Ψ
avgbe not more than default saltus step threshold value, then judge island effect does not occur, proceed the phase hit in next cycle detection cycle, and keep electricity generation system to be incorporated into the power networks.
From said method step, the island detection method control procedure that the embodiment of the present application provides is simple, is convenient to realize; Can detect in the cycle detection cycle after isolated island occurs, detection efficiency is high; Do not need the output to inverter to add disturbance quantity, can not have an impact to the output quality of power supply of inverter; Mean value according to phase hit judges, eliminates various disturbing factor, improves accuracy of detection; Reduce check frequency.Therefore, the embodiment of the present application solves the problem of prior art.
Preferably, in the embodiment of the present application, above-mentioned default saltus step threshold value is generally set to 3 ~ 10 degree, specifically determines according to actual conditions, improves the flexibility of islanding detect.
With reference to Fig. 2, for the embodiment of step described in embodiment one, the embodiment of the present application two provides another kind of island detection method, comprises the steps:
S1, periodic samples is carried out to the three-phase voltage of grid-connected inverters point;
S2, by successively carrying out coordinate transform and high-pass filtering to described three-phase voltage, calculate described in each sampling period and the real-time voltage angle θ of site;
Concrete, to described three-phase voltage u
a, u
b, u
ccarry out clarke coordinate transform, obtain the α axle component u of described grid-connected point voltage in two-phase rest frame (alpha-beta coordinate system)
αwith beta-axis component u
β; To described α axle component u
αwith beta-axis component u
βcarry out high-pass filtering, with filtering DC component wherein, get rid of humorous wave interference; According to filtered α axle component u
αwith beta-axis component u
βalpha-beta coordinate system calculates the real-time voltage angle θ of described also site, i.e. θ=atan (u
β/ u
α).
S3, build a phase-locked loop based on described real-time voltage angle θ, to carry out phase-locked to grid-connected point voltage phase place;
Concrete, as shown in Figure 3, the above-mentioned phase-locked loop based on described real-time voltage angle θ, comprising:
PI governing loop, namely to the phase-locked angle Φ that described real-time voltage angle and described phase-locked loop export
plldifference carry out PI adjustment;
Frequency of phase locking calculates link, the angle step ω of the output namely regulated according to described PI and each sampling period change corresponding to electrical network nominal reference angular frequency
stepcalculate the frequency of phase locking ω of described phase-locked loop in each sampling period
pll;
Phase-locked angle calculates link, namely to described frequency of phase locking ω
plladd up, obtain described phase-locked angle Φ
pll.
Wherein, angle step ω
stepoccurrence by electrical network nominal reference frequency f and sample frequency f
sdetermine, i.e. ω
step=2 π f/f
s.
The frequency of phase locking ω of described phase-locked loop in S4, a calculating power frequency period
pllmean value ω
avg;
Namely
wherein, n is the sampling number (sampling period number) in a power frequency period; ω
plli () is the frequency of phase locking in i-th sampling period.
S5, according to previous cycle sense cycle inter-sync level angle Φ
avginitial value Φ
avg_0with the mean value ω of described frequency of phase locking
avgcalculate each sampling period inter-sync level angle Φ in previous cycle sense cycle
avg;
Namely pass through at Φ
avg_0to ω on basis
avgadd up, obtain the Φ in each sampling period
avg, the synchronizing voltage angle Φ in i-th sampling period is represented by following formula
avg_ifor:
wherein, t is the sampling period.
In first cycle detection cycle (power frequency period can be a cycle detection cycle) of cycle detection, Φ
avg_0value is the phase-locked angle Φ of phase-locked loop
pll.
S6, calculate described real-time voltage angle θ and synchronizing voltage angle Φ in each sampling period
avgdifference, obtain described in each sampling period and the phase hit value Ψ of site;
Namely the phase hit value Ψ in i-th sampling period
ifor: Ψ
i=θ
i-Φ
avg_iwherein, θ i is the real-time voltage angle in i-th sampling period.
S7, when the synchronizing voltage angle of current sample period is greater than 2 π, calculate the mean value Ψ of described phase hit value Ψ in previous cycle sense cycle
avg, and perform step S8 and S9 respectively;
Namely for each sampling period, current synchronizing voltage angle Φ is being determined
avgafter, judge whether it is greater than 2 π, if so, then illustrate that accumulation periods has reached a cycle detection cycle, can carry out Ψ
avgcalculating; Otherwise do not reach a cycle detection cycle, continue to detect the phase hit value Ψ determining the next sampling period.
The mean value Ψ of phase hit value Ψ
avgcomputing formula be:
If the mean value Ψ of the described phase hit value of S8
avgbe greater than default saltus step threshold value B, then judge that isolated island occurs;
S9, judge the mean value Ψ of described phase hit value
avgabsolute value whether be greater than preset upgrade threshold value A, if so, then perform step S10, otherwise perform step S11;
S10, in the next cycle detection cycle, the initial value of synchronizing voltage angle is that in the previous cycle detection cycle, the synchronizing voltage angle in last sampling period deducts 2 π, the mean value of frequency of phase locking continues to use the mean value of the frequency of phase locking in previous cycle detection cycle, and returns step S5;
Namely | Ψ
avg| during >A, Φ
avg_0(x+1)=Φ
avg_n(x)-2 π; Wherein, Φ
avg_0(x+1) be the initial value of the synchronizing voltage angle in a (x+1)th cycle detection cycle, Φ
avg_nx () is the synchronizing voltage angle Φ in last sampling period in the xth cycle detection cycle
avg_n;
ω
avg(x+1)=ω
avg(x); Wherein, ω
avg(x+1) be the mean value of the frequency of phase locking in a (x+1)th cycle detection cycle, ω
avgthe mean value of the frequency of phase locking in an x xth cycle detection cycle that () calculates for step S4.
After the initial value of synchronizing voltage angle and the mean value of frequency of phase locking are determined, namely realize the islanding detect in next cycle detection cycle by step S5 and subsequent step.
S11, by the phase-locked angle Φ of phase-locked loop
pllas the initial value of the synchronizing voltage angle in next cycle detection cycle, and return step S4.
Namely | Ψ
avg| during≤A, the initial value Φ of the synchronizing voltage angle in a (x+1)th cycle detection cycle
avg_0(x+1)=Φ
pll; By the mean value of the frequency of phase locking in a method determination (x+1)th cycle detection cycle described in step S4, and then execution subsequent step realizes cycle detection successively.
The embodiment of the present application the detection data according to previous cycle sense cycle, to be judged whether that by step S8 island effect occurs while, also according to the mean value Ψ of described phase hit value
avg, determined the synchronizing voltage angle Φ in next cycle detection cycle by step S10 or S11
avginitial value Φ
avg_0and the mean value ω of described frequency of phase locking
avg, for the islanding detect in next cycle detection cycle is ready, achieve cycle detection.
Above-described embodiment two provides the preferred forms of the embodiment of the present application: by coordinate transform and high-pass filtering, obtains the real-time grid angle of the grid-connected point voltage without DC component interference; By phase-locked loop to and the level angle of site is carried out phase-locked, and according to the frequency of phase locking determination synchronizing voltage angle of phase-locked loop; According to phase hit value, the i.e. difference of described real-time voltage angle and synchronizing voltage angle, mean value within a cycle detection cycle judges whether island effect occurs, determine next cycle detection cycle correlation computations initial value according to the mean value of this phase hit value simultaneously, realize cycle detection.Visible, the island detection method control procedure that the embodiment of the present application provides is simple, is convenient to realize; Can detect in the cycle detection cycle after isolated island occurs, detection efficiency is high; Do not need the output to inverter to add disturbance quantity, can not have an impact to the output quality of power supply of inverter; Mean value according to phase hit judges, eliminates various disturbing factor, improves accuracy of detection; Reduce check frequency.
Concrete, in the embodiment of the present application, default renewal threshold value A and default saltus step threshold value B all set according to practical situations; General default saltus step threshold value B is set to 3 ~ 10 degree, presets and upgrades 0.1 ~ 0.4 times that threshold value A is set to described default saltus step threshold value B.
The island detection method that the embodiment of the present application provides, essence is passive islanding detect method; It judges the default saltus step threshold value B whether isolated island occurs, conversion is voltage threshold or frequency threshold, passed through under same environment/under-voltage and mistake/under-frequency detection method detect set by judgment threshold, therefore the check frequency of island detection method that the embodiment of the present application provides is much smaller than existing passive islanding detect method; On the other hand, relative to existing active islanding detect method, the embodiment of the present application adds disturbance quantity without the need to the output to inverter, can not have an impact to the output quality of power supply of inverter.Therefore, the embodiment of the present application has taken into account accuracy of detection and the quality of power supply, well overcomes the drawback of existing island detection method.
Accordingly, the embodiment of the present application three additionally provides a kind of isolated island detecting device; As shown in Figure 4, this device comprises sampling unit 100, real-time voltage angle calculation unit 200, synchronizing voltage angle calculation unit 300, phase hit value computing unit 400, phase hit average calculation unit 500 and isolated island identifying unit 600.
Wherein, sampling unit 100, for carrying out periodic samples to the three-phase voltage of grid-connected inverters point;
Real-time voltage angle calculation unit 200, for calculating the real-time voltage angle θ of described also site in each sampling period according to described three-phase voltage;
Synchronizing voltage angle calculation unit 300, for building a phase-locked loop based on described real-time voltage angle θ, and determines the synchronizing voltage angle Φ av of described real-time voltage angle θ in each sampling period according to described phase-locked loop
g;
Phase hit value computing unit 400, for calculating described real-time voltage angle θ and synchronizing voltage angle Φ in each sampling period
avgdifference, obtain described in each sampling period and the phase hit value Ψ of site;
Phase hit average calculation unit 500, for working as described synchronizing voltage angle Φ
avgwhen being greater than 2 π, calculate the mean value Ψ of described phase hit value Ψ within a cycle detection cycle
avg;
Isolated island identifying unit 600, for judging whether the mean value of described phase hit value is greater than default saltus step threshold value, if so, then judges that isolated island occurs.
The specific works principle of said apparatus can refer to foregoing embodiments one, repeats no more herein.Visible, the isolated island detecting device control procedure that the embodiment of the present application provides is simple, is convenient to realize; Can detect in the cycle detection cycle after isolated island occurs, detection efficiency is high; Do not need the output to inverter to add disturbance quantity, can not have an impact to the output quality of power supply of inverter; Mean value according to phase hit judges, eliminates various disturbing factor, improves accuracy of detection; Reduce check frequency.
Corresponding to foregoing embodiments two, the embodiment of the present application four provides another kind of isolated island detecting device; As shown in Figure 5, this device comprises: sampling unit 100, real-time voltage angle calculation unit 200, synchronizing voltage angle calculation unit 300, phase hit value computing unit 400, phase hit average calculation unit 500 and isolated island identifying unit 600.
Concrete, sampling unit 100, for carrying out periodic samples to the three-phase voltage of grid-connected inverters point.
Real-time voltage angle calculation unit 200 at least comprises following 3 modules:
Coordinate transformation module 201, for carrying out clarke coordinate transform to described three-phase voltage, obtains described grid-connected point voltage at the α axle component of two-phase rest frame and beta-axis component;
High-pass filtering module 202, for carrying out high-pass filtering, to filter DC component to described α axle component and beta-axis component;
Real-time angular computing module 203, for calculating the real-time voltage angle θ of described also site according to filtered described α axle component and beta-axis component.
Synchronizing voltage angle calculation unit 300 comprises: phase-locked loop module 310 and synchronous angle calculation module 320; Wherein, with reference to Fig. 6, the Digital Implementation of phase-locked loop module 310 corresponds to phase-locked loop shown in Fig. 3, comprising: PI adjustment module 311, frequency of phase locking computing module 312 and phase-locked angle computing module 313; Synchronous angle calculation module 320 obtains the synchronizing voltage angle in each sampling period by accumulation calculating, comprises initial value determination module 321 and accumulation calculating module 322.
More specifically, PI adjustment module 311, for the phase-locked angle Φ exported described real-time voltage angle and described phase-locked loop
plldifference carry out PI adjustment, and export PI regulate result.
Frequency of phase locking computing module 312, for regulating the angle step ω of result and each sampling period change corresponding to electrical network nominal reference angular frequency according to described PI
stepcalculate the frequency of phase locking ω of described phase-locked loop in each sampling period
pll.
Phase-locked angle computing module 313, for described frequency of phase locking ω
plladd up, obtain described phase-locked angle Φ
pll.
Initial value determination module 321, for the mean value Ψ according to described phase hit value in the upper cycle detection cycle
avgdetermine described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value and the mean value ω of described frequency of phase locking
avg.
Accumulation calculating module 322, at described synchronizing voltage angle Φ
avginitial value basis on, to the mean value ω of described frequency of phase locking
avgadd up, obtain described synchronizing voltage angle Φ
avg.
Phase hit value computing unit 400, for calculating described real-time voltage angle θ and synchronizing voltage angle Φ in each sampling period
avgdifference, obtain described in each sampling period and the phase hit value Ψ of site;
Phase hit average calculation unit 500, for working as described synchronizing voltage angle Φ
avgwhen being greater than 2 π, calculate the mean value Ψ of described phase hit value Ψ within a cycle detection cycle
avg;
Isolated island identifying unit 600, for judging whether the mean value of described phase hit value is greater than default saltus step threshold value, if so, then judges that isolated island occurs.
Preferably, in the embodiment of the present application cyclic process, according to the synchronizing voltage angle Φ in the next cycle detection cycle that phase hit average calculation unit 500 calculates
avginitial value and the mean value ω of described frequency of phase locking
avg; Accordingly, initial value determination module 321 comprises:
Upgrade judge module 3211, for judging the mean value Ψ of described phase hit value
avgabsolute value whether be greater than preset upgrade threshold value.
First initial value determination module 3212, for when the judged result of described first judge module is for being, the synchronizing voltage angle obtain last sampling period of a upper cycle detection cycle (i.e. cycle detection cycle) and 2 π subtract each other, and obtain described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value, and by the mean value ω of the frequency of phase locking in upper one-period
avgas the mean value ω of the frequency of phase locking in previous cycle sense cycle
avg; And then trigger the synchronizing voltage angle that accumulation calculating module 322 calculates each sampling period in previous cycle sense cycle.
Second initial value determination module 3213, for when the judged result of described first judge module is no, by described phase-locked angle Φ
pllas synchronizing voltage angle Φ described in previous cycle sense cycle
avginitial value, and by the frequency of phase locking ω that calculates frequency of phase locking computing module 312
pllin a power frequency period, carry out cumulative and average calculating operation, obtain the mean value ω of frequency of phase locking in previous cycle sense cycle
avg; And then trigger the synchronizing voltage angle that accumulation calculating module 322 calculates each sampling period in previous cycle sense cycle.
It should be noted that, when cycle detection starts, due to Ψ
avgwithout initial value, its absolute value is considered as 0, therefore determines the initial value of synchronizing voltage angle and the mean value of frequency of phase locking in first cycle detection cycle by the second initial value determination module 3213.
The isolated island detecting device provided from above-described embodiment four, the application, by coordinate transform and high-pass filtering, obtains the real-time grid angle of the grid-connected point voltage without DC component interference; By phase-locked loop to and the level angle of site is carried out phase-locked, and according to the frequency of phase locking determination synchronizing voltage angle of phase-locked loop; According to phase hit value, the i.e. difference of described real-time voltage angle and synchronizing voltage angle, mean value within a cycle detection cycle judges whether island effect occurs, determine next cycle detection cycle correlation computations initial value according to the mean value of this phase hit value simultaneously, realize cycle detection.Therefore, the isolated island detecting device control procedure that the embodiment of the present application provides is simple, is convenient to realize; Can detect in the cycle detection cycle after isolated island occurs, detection efficiency is high; Do not need the output to inverter to add disturbance quantity, can not have an impact to the output quality of power supply of inverter; Mean value according to phase hit judges, eliminates various disturbing factor, improves accuracy of detection; Reduce check frequency.
One of ordinary skill in the art will appreciate that all or part of flow process realized in above-described embodiment method, that the hardware that can carry out instruction relevant by computer program has come, described program can be stored in a computer read/write memory medium, described program, when performing, can comprise the flow process of the embodiment as above-mentioned each side method.Wherein, described storage medium can be magnetic disc, CD, read-only store-memory body (Read-Only Memory, ROM) or random store-memory body (Random Access Memory, RAM) etc.
It should be noted that, in this article, the such as relational terms of first and second grades and so on is only used for an entity or operation to separate with another entity or operating space, and not necessarily requires or imply the relation that there is any this reality between these entities or operation or sequentially.
Each embodiment in this specification all adopts the mode of going forward one by one to describe, between each embodiment identical similar part mutually see, what each embodiment stressed is the difference with other embodiments.To the above-mentioned explanation of the disclosed embodiments, professional and technical personnel in the field are realized or uses the application.To be apparent for those skilled in the art to the multiple amendment of these embodiments, General Principle as defined herein when not departing from the spirit or scope of the application, can realize in other embodiments.Therefore, the application can not be restricted to these embodiments shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.
Claims (10)
1. an island detection method, is characterized in that, comprising:
Periodic samples is carried out to the three-phase voltage of grid-connected inverters point;
The real-time voltage angle θ of described also site in each sampling period is calculated according to described three-phase voltage;
Build a phase-locked loop based on described real-time voltage angle θ, and determine the synchronizing voltage angle Φ of described real-time voltage angle θ in each sampling period according to described phase-locked loop
avg;
Calculate described real-time voltage angle θ and synchronizing voltage angle Φ in each sampling period
avgdifference, obtain described in each sampling period and the phase hit value Ψ of site;
As described synchronizing voltage angle Φ
avgwhen being greater than 2 π, calculate the mean value Ψ of described phase hit value Ψ within a cycle detection cycle
avg;
If the mean value of described phase hit value is greater than default saltus step threshold value, then judge that isolated island occurs.
2. island detection method according to claim 1, is characterized in that, describedly builds a phase-locked loop based on described real-time voltage angle θ, comprising:
To the phase-locked angle Φ that described real-time voltage angle and described phase-locked loop export
plldifference carry out PI adjustment;
The output regulated according to described PI and electrical network nominal reference frequency ω
stepcalculate the frequency of phase locking ω of described phase-locked loop in each sampling period
pll;
To described frequency of phase locking ω
plladd up, obtain described phase-locked angle Φ
pll.
3. island detection method according to claim 2, is characterized in that, the described synchronizing voltage angle Φ determining described real-time voltage angle θ in each sampling period according to described phase-locked loop
avg, comprising:
According to the mean value Ψ of described phase hit value in the upper cycle detection cycle
avgdetermine described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value and the mean value ω of described frequency of phase locking
avg;
At described synchronizing voltage angle Φ
avginitial value basis on, to the mean value ω of described frequency of phase locking
avgadd up, obtain described synchronizing voltage angle Φ
avg.
4. island detection method according to claim 3, is characterized in that, the described mean value Ψ according to described phase hit value in the upper cycle detection cycle
avgdetermine described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value and the mean value ω of described frequency of phase locking
avg, comprising:
Judge the mean value Ψ of described phase hit value
avgabsolute value whether be greater than preset upgrade threshold value;
If so, then by the synchronizing voltage angle Φ in the upper cycle detection cycle
avgsubtract each other with 2 π, obtain described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value, and by the mean value ω of the frequency of phase locking in the upper cycle detection cycle
avgas the mean value ω of the frequency of phase locking in previous cycle sense cycle
avg;
If not, then by described phase-locked angle Φ
pllas synchronizing voltage angle Φ described in previous cycle sense cycle
avginitial value, and to described frequency of phase locking ω
pllin a power frequency period, carry out cumulative and average calculating operation, obtain the mean value ω of described frequency of phase locking
avg.
5. island detection method according to claim 4, is characterized in that, described default renewal threshold value is 0.1 ~ 0.4 times of described default saltus step threshold value.
6. the island detection method according to any one of Claims 1 to 5, is characterized in that, the described real-time voltage angle θ calculating described also site in each sampling period according to described three-phase voltage, comprising:
Clarke coordinate transform is carried out to described three-phase voltage, obtains described grid-connected point voltage at the α axle component of two-phase rest frame and beta-axis component;
High-pass filtering is carried out, to filter DC component to described α axle component and beta-axis component;
The real-time voltage angle θ of described also site is calculated according to filtered described α axle component and beta-axis component.
7. an isolated island detecting device, is characterized in that, comprising:
Sampling unit, for carrying out periodic samples to the three-phase voltage of grid-connected inverters point;
Real-time voltage angle calculation unit, for calculating the real-time voltage angle θ of described also site in each sampling period according to described three-phase voltage;
Synchronizing voltage angle calculation unit, for building a phase-locked loop based on described real-time voltage angle θ, and determines the synchronizing voltage angle Φ of described real-time voltage angle θ in each sampling period according to described phase-locked loop
avg;
Phase hit value computing unit, for calculating described real-time voltage angle θ and synchronizing voltage angle Φ in each sampling period
avgdifference, obtain described in each sampling period and the phase hit value Ψ of site;
Phase hit average calculation unit, for working as described synchronizing voltage angle Φ
avgwhen being greater than 2 π, calculate the mean value Ψ of described phase hit value Ψ within a cycle detection cycle
avg;
Isolated island identifying unit, for judging whether the mean value of described phase hit value is greater than default saltus step threshold value, if so, then judges that isolated island occurs.
8. isolated island detecting device according to claim 7, is characterized in that, described synchronizing voltage angle calculation unit comprises: phase-locked loop module and synchronous angle calculation module; Wherein,
Described phase-locked loop module comprises:
PI adjustment module, for the phase-locked angle Φ exported described real-time voltage angle and described phase-locked loop
plldifference carry out PI adjustment, and export PI regulate result;
Frequency of phase locking computing module, for regulating result and electrical network nominal reference frequency ω according to described PI
stepcalculate the frequency of phase locking ω of described phase-locked loop in each sampling period
pll;
Phase-locked angle computing module, for described frequency of phase locking ω
plladd up, obtain described phase-locked angle Φ
pll;
Described synchronous angle calculation module comprises:
Initial value determination module, for the mean value Ψ according to described phase hit value in the upper cycle detection cycle
avgdetermine described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value and the mean value ω of described frequency of phase locking
avg;
Accumulation calculating module, at described synchronizing voltage angle Φ
avginitial value basis on, to the mean value ω of described frequency of phase locking
avgadd up, obtain described synchronizing voltage angle Φ
avg.
9. isolated island detecting device according to claim 8, is characterized in that, described initial value determination module comprises:
Upgrade judge module, for judging the mean value Ψ of described phase hit value
avgabsolute value whether be greater than preset upgrade threshold value;
First initial value determination module, for when the judged result of described first judge module is for being, by the synchronizing voltage angle Φ in the upper cycle detection cycle
avgsubtract each other with 2 π, obtain described synchronizing voltage angle Φ in previous cycle sense cycle
avginitial value, and by the mean value ω of the frequency of phase locking in the upper cycle detection cycle
avgas the mean value ω of the frequency of phase locking in previous cycle sense cycle
avg;
Second initial value determination module, for when the judged result of described first judge module is no, by described phase-locked angle Φ
pllas synchronizing voltage angle Φ described in previous cycle sense cycle
avginitial value, and to described frequency of phase locking ω
pllin a power frequency period, carry out cumulative and average calculating operation, obtain the mean value ω of described frequency of phase locking
avg.
10. the isolated island detecting device according to any one of claim 7 ~ 9, is characterized in that, described real-time voltage angle calculation unit comprises:
Coordinate transformation module, for carrying out clarke coordinate transform to described three-phase voltage, obtains described grid-connected point voltage at the α axle component of two-phase rest frame and beta-axis component;
High-pass filtering module, for carrying out high-pass filtering, to filter DC component to described α axle component and beta-axis component;
Real-time angular computing module, for calculating the real-time voltage angle θ of described also site according to filtered described α axle component and beta-axis component.
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