CN107749626A - A kind of background harmonic voltage that can exclude influences to detect the detection method of true filter effect - Google Patents
A kind of background harmonic voltage that can exclude influences to detect the detection method of true filter effect Download PDFInfo
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- CN107749626A CN107749626A CN201711257473.XA CN201711257473A CN107749626A CN 107749626 A CN107749626 A CN 107749626A CN 201711257473 A CN201711257473 A CN 201711257473A CN 107749626 A CN107749626 A CN 107749626A
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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
- H02J3/01—Arrangements for reducing harmonics or ripples
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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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/16—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for capacitors
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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
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
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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
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
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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
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
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- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- General Physics & Mathematics (AREA)
- Supply And Distribution Of Alternating Current (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
The invention discloses a kind of background harmonic voltage that can exclude to influence to detect the detection method of true filter effect.This can exclude background harmonic voltage and influence to detect detection method of true filter effect can to detect the Current Voltage of fundamental wave and power parameter and selectively detect predetermined each harmonic voltage x current; and the overcurrent-overvoltage coefficient of each input filter branch capacitor is calculated according to each filter branch parameter and current each harmonic voltage, so as to substitute unreasonable method of the total harmonic distortion all used at present as protection definite value.The actual filter effect that user's exclusion background harmonic voltage influence in user's zero load and the predetermined individual harmonic current parameter that PCC points are flowed through during the whole filter branch of fully loaded lower input, is calculated according to measurement result twice can be detected.Controller allows Large Copacity low order filter branch being subdivided into multiple branch roads, ensures filtering and reactive-load compensation effect in load wide variation.
Description
Technical field
The present invention relates to the detection method field for excluding background harmonicses, more particularly to one kind can exclude background harmonic voltage shadow
Ring the detection method for detecting true filter effect.
Background technology
Harmonic wave refers to whole more than fundamental frequency obtained by being decomposed to periodicity non-sine of ac progress Fourier space
Each component of degree n n of several times, commonly referred to as higher hamonic wave, and fundamental wave refers to its frequency and power frequency (50Hz) identical component.High order is humorous
The interference of ripple is that one big " public hazards " of the quality of power supply are influenceed in current power system, it would be highly desirable to is taken some countermeasures.With industrial technology
Rapid development and a large amount of uses of power electronic devices, harmonic load or referred to as active load in power system increasingly increase
More, harm is more serious caused by harmonic wave.In addition some cause specifics, scene operation is nearly all filter effect extreme difference
" detuning (also known as detune, anti-tuning, off resonance) filtering " device so that some partial electric grid harmonic pollutions are already close to even
Beyond the index of national regulations.Increasingly attracted attention for the research and extension use of this harmonic reactive-load compensation equipment.
Harmonic reactive-load compensation equipment is divided into active and passive two major class at present, and active performance is good but price is with respect to mistake
Height, so still accounting for main flow with passive class in market.Divide according to filter effect, tuning filtering and anti-tuning filtering can be divided into
(also known as detuning filtering), tuning filtering are to filter out harmonic current caused by load in order to as far as possible more, and higher level is flowed into reduce
The harmonic current of power network；It is to enter filter branch to reduce harmonic current as far as possible to ensure the safety of capacitor to detune filtering,
Actually filter action very little." the Static Filtering compensation equipment " that is divided into again using controllable silicon as switch of passive class connects with to exchange
Tentaculum is " the dynamic filter compensation equipment " of switch, static quick action but controllable silicon both ends leading in the presence of 1~2V or so
Logical pressure drop is so as to produce certain thermal losses, and cost is slightly higher, does not dynamically have additional heating losses but responsiveness is slow, cost
It is low.Either dynamic or static device, it is required for controller accurately to measure the power harmony wave parameter of system at a high speed, with
Guarantee correctly balance it is idle, filter out harmonic current；To ensure capacitor safe operation, controller allows for detecting each input
Filter branch capacitor real-time overcurrent-overvoltage coefficient；Capacitor capacity reduction factor must be detected in longtime running, and is repaiied
The capacitance parameter of positive filter branch is to ensure to detect the correctness of overcurrent-overvoltage coefficient.
Up to the present, all documents and materials there is no the controller for being capable of the overvoltage of detection filter capacitor over-current with product.
Due to the presence of a large amount of harmonic loads, and what is largely run is " detuning filter ", causes most partial electric grids all to exist
Background harmonic voltage.Higher level's power network of most users is all 10kV, and the voltage harmonic of national regulations 10kV power networks is always abnormal
Variability should be less than being equal to 4%, but it is actual some already close to even substantially exceeding 4%！But even if this 4% background harmonics is electric
Pressure, it is not harmonic load for itself, only by the user for having filled conventional capacitive cabinet, can causes capacitor in certain system sometimes yet
The amplified harmonic current effect that can not be ignored under parameter and input state, causes the serious excessively stream of capacitor and damage, even
It is on fire from explosion！This example is rare absolutely not.For the user by dress tuning filtering device, background harmonic voltage can be become by user
The harmonic impedance of depressor is by a large amount of harmonic current injection filters, first, increase the overcurrent-overvoltage pressure of filter condenser, two
Be power supply department check and accept when flow through PCC points individual harmonic current be far longer than national standard defined " i-th at points of common connection
The h subharmonic current permissible values I of individual userhi", it is unqualified filter effect to be judged to！Although this be user it is free for higher level
Power network filters！Influence of the background harmonic voltage to filter effect how is removed, draws true filter effectOn some scholarly journals
Also have a discussion much to this problem, but all it is simple and easy it is accurate rationally, especially with controller Solve on site this problem
Method, user's harmonic effect can not correctly be judged by ultimately causing power supply department.
The more full controller of function can measure the fundamental current voltage and power parameter of customer charge system at present, measurement
Individual harmonic current voltage parameter, total harmonic distortion THDu and current harmonics total harmonic distortion THDi is measured, and with THDu
Protection act definite value as filter overcurrent-overvoltage.THDu be each harmonic voltage squared and again evolution and divided by fundamental wave
The percentage that voltage is drawn, its increase can only illustrate that filter branch capacitor over-current crosses the trend for being pressed with increase, be actually
Which subharmonic voltage increase causes which bar branch road overcurrent-overvoltage unknown again, so it is not an accurate rational protection
Definite value.To further illustrate THDu irrationality, a simple case is lifted：
It is assumed that the three-phase filter branch capacitor of certain unit design is 50kVAR/0.48kV, rated current 72.17A.Series connection
Reactor ignores the resistance of reactor according to the 6% of capacitive reactance.Run the fundamental voltage U1=400V at scene；
The first state：[4,5,7,11,13] subharmonic voltage containing ratio is HRu={ 0,4,3,2,1 } %, can calculate electricity
Press total harmonic distortion THDu=5.477%, excessively stream coefficient=95.19% of capacitor；Over-pressed coefficient=96.97%；
Second of state：[4,5,7,11,13] subharmonic voltage containing ratio is HRu={ 2,3,2,1,1 } %, can calculate electricity
Press total harmonic distortion THDu=4.359%, excessively stream coefficient=190.53% of capacitor；Over-pressed coefficient=136.40%；
Why second of state THDu is smaller and excessively stream coefficient is very bigReason be increase only 2% 4 subharmonic electricity
Pressure, but generates 100.23A 4 subharmonic currents, and is in amplification section！Because 5 subharmonic impedances of branch road be induction reactance+
J0.4608 Europe, and 4 subharmonic impedances are capacitive reactance and only-j0.04608 Europe, differ 10 times！This example further illustrates THDu and done
Protect the irrationality of definite value.
The harmonic load of general most users uses the pulse wave rectifier circuit of three-phase six, and caused is 6n ± 1 time spy
Levy harmonic current, i.e., 5,7,11,13 ... subharmonic currents, set filter branch is generally 5,7,11 times, or is added
13 times or 13 high-pass filtering branch roads.The total reactive compensation capacity of each branch road will reach the reactive requirement of busy hour, and each
The capacity distribution of branch road, about according to the subharmonic current amplitude is proportional to, the overtone order for being inversely proportional to it is allocated.Although
High reps filter branch is also contemplated that the amplification factor to low order number harmonic current, can suitably heighten its capacity in design,
But because the lower harmonic current of number is bigger, so the capacity that last result is often 5 filter branch can typically account for
40% or more of total capacity.According to conventional need no matter amount of capacity, each secondary filter branch can only be set all the way, input filtering
The order of branch road must be from low order to high order, and the order of excision is opposite.The load of user is typically by power harmony wave property phase
Same or different multiple loads are formed in parallel, and as the amount of going into operation and production technology are different, put into the power harmony wave property of load
All different, this results in that 5 times maximum filter branch of capacity can not be put at all under normal Smaller load.If 5 times branch road is thin
It is divided into if multiple loops with regard to that can solve the problems, such as reactive-load compensation.But because controller can not measure each loop overcurrent-overvoltage ginseng
Number, can not judge whether each loop is safe for operation, so traditional design does not allow subdivision group.
In order to solve this contradiction, some producers take increase is a set of can be similar to 5 filter branch with fine control, capacity
Anti- tuning filtering branch road, as the reactive-load compensation before 5 filter branch can be put into, that is to say, that 5 times filtering branch
Before the input of road, much filter actions are there is no；Such a process increases filter effect under investment and Smaller load is poor.Look into
The patent No. 200720120625.7 and patent No. 200820189387.X files, all specially there is provided the filtering branch of 3 times of low capacity
Road, and No. 200720120625.7 patents are mentioned, when 5 filter branch of Large Copacity can not be put into, according to 3 times 11 times and
The sequential selection input branch road of 7 times；Certainly 3 branch roads are first put into and do not have overcurrent-overvoltage danger, but are first put into 11 times or 7
Secondary branch road, for having not been put to 5 filter branch filtering and 5 larger subharmonic currents, more serious amplification can be produced,
And cause the overcurrent-overvoltage of the branch road capacitor of input.The two other patents, which are all mentioned employing, can measure harmonic parameters
Comprehensive control instrument RVT and control switching programmable controller PLC, undoubtedly add customer investment.
At present largely run detune filter design it is very simple, according to estimation customer charge size determine compensation hold
Amount, estimation scene have harmonic wave just to connect 6%~7% reactor, and capacitor selects 450V or 480V；Used controller function letter
It is single.Some call parameters can not be measured in operation so as to judge whether operation is abnormal, repairing can not be provided after failure or changed
The scientific basis made.
For professional filter manufacturer, when especially producing tuning filtering device, it typically can all arrive first user and show
Field measures, even thousands of kilometers, then integrate all parameters and carry out design of Simulation, determines final scheme, and each side
The reason for case is all " case ", and this is also that such filter is expensive, and most designing units never design it.
The purpose for detuning filtering is to prevent harmonic current from entering capacitor to ensure the safety of capacitor, and purpose is exactly not filter in other words
Ripple！Exactly because also a large amount of operations for detuning filter, turn into the high original of many partial electric grid background harmonic voltages
Cause.
If the mentality of designing to disaccustom, multiple are subdivided into by 5 times of capacity maximum or including 7 filter branch
Road, it is put into operation under Smaller load, play filter action, must just solve 1) each branch road filter condenser whether
Overcurrent-overvoltage；2) follow-up loop can be put into according to power factor under overcurrent-overvoltage state, if reverse-blocking tetrode thyristor is quiet
State filter can be put into immediately certainly, if how the dynamic filter device of A.C. contactor switch is according to overcurrent-overvoltage journey
Degree determines follow-up input speed；3) it is some in short-term or long-time High Power Factor high harmonic content load condition, filter capacity
When having thrown foot but also filter capacitor overcurrent-overvoltage state, how as early as possible the problem of neutralizing capacitor pressure；4) needing
Protection act is wanted to determine excision speed according to overcurrent-overvoltage degree when cutting off.5) background harmonicses be present in higher level's power network of user
When, the actual filter effect of user's filter can be measured；6) after condenser capacity reduces in longtime running, necessarily cause
The change of compensation capacity, filter effect and capacitor over-voltage and over-current.Controller should be able to detect this change, and take corresponding
Control measure.
Because harmonic measure meter specially is expensive and professional very strong, general user includes very big company not
It can buy；It can measure that the current price of filtering compensation controller of each harmonic is also all expensive, and this is resulted in after going wrong, use
Pulled between family, equipment manufacturer and component supplier unclear " lawsuit ".So can not analyze accident true cause and really
Surely the corrective measure that should be taken.
The content of the invention
Accurate, cheap, energy sensing capacitor over-voltage and over-current is measured it is an object of the invention to provide one kind and can be arranged
Except background harmonic voltage influences to detect the detection method of true filter effect.
The above-mentioned purpose of the present invention is achieved through the following technical solutions：
A kind of background harmonic voltage that can exclude influences to detect the detection method of true filter effect, and implementation steps are as follows：
(1) harmonic wave of corresponding different numbers reads sampled data using different address pointer table：Only detection has the present invention
2,3,4,5,7,11,13,17,19,23,25 subharmonic parameters of practical value, each times harmonic are separately provided a spy
Determine sampled data address pointer form, calculate and be used as in fixed array write-in program according to Fourier's Computing Principle, press
The address pointer of form directly reads sampled data from sampled data, calculates the harmonic parameters of corresponding number；
(2) overcurrent-overvoltage of detection filter branch road filter capacitor：By each branch road capacitor, reactor and reactor resistance
Parameter input controller, controller calculate the fundamental wave and each harmonic harmonic wave Y of the branch road according to their parameterLh(h=1,2,
3rd, 4,5,7,11,13,17,19,23,25, wherein h=1 is fundamental wave), controller detects the fundamental wave and each harmonic electricity of bus
Press Uh, then the fundamental wave and individual harmonic current I of the branch road are flowed throughh=Uh*YLh, and then individual harmonic current is calculated in capacitor
Fundamental wave and each harmonic pressure drop U caused by upperCh=Ih*XC/ h, including the individual harmonic current including fundamental current
Evolution is exactly the current effective value for flowing through capacitor to quadratic sum again, divided by rated capacitor electric current is exactly excessively stream coefficient, same electricity
Each harmonic voltage drop sum on container including fundamental voltage is exactly the peak voltage that capacitor is born, and peak voltage removes
It is exactly over-pressed coefficient with rated capacitor voltage, the overcurrent-overvoltage coefficient of capacitor is only the accurate definite value of capacitor protection；
(3) volume reduction of detection filter capacitor：Because present used filter condenser is all self-healing, in operation
Capacity can slowly reduce, XCIncrease, thus for it is each can independent switching loop, carry out in each input and respectively when cutting off
The measurement of single compensation capacity and record, with the result measured several times to XCIt is modified, and with revised XCRecalculate
Its harmonic admittance YLh, the foundation as the measurement of overcurrent-overvoltage coefficient；
(4) influence of the background harmonic voltage to filter effect is removed：When background harmonic voltage is not present in user, load institute
A caused harmonic current part is to flow into filter branch ZLhIFLh, remainder IFShSystem, i.e. I are flowed into by PCC pointsPCC
=IFShIf IPCC≤Ihi, then illustrate that user's filter effect is up to standard.Background harmonic voltage U be present in userShAnd in load
Z is acted solely under Light ConditionLhWhen, flow through the electric current I of PCC pointsPh.0=ISh, and IShPurely it is the background harmonicses by system
Voltage causes；The background harmonic voltage U under load full load conditionShWith Load harmonic electric current IFhCollective effect is in ZLhWhen, now flow
Electric current through PCC points is I according to phasor relationPh.1=IFSh+ISh, due to IShPresence, can typically cause IPCCMuch larger than IFSh,
Cause the underproof illusion of filter effect；Accurate measurement IPh.0And IPh.1The amplitude of two phasors and their relative angle, then
I is drawn by phasor computingFSh, i.e. IFSh=IPCC-ISh；IFShExactly need the I examinedhi。
(5) user is allowed to be finely divided group to low order Large Copacity filter branch：It is finely divided by 5 times or together with 7 times to be several
Individual loop, minimum packets capacity disclosure satisfy that reactive-load compensation during normal minimum load；
(6) flexible switching definite value is set and coordinated with overcurrent-overvoltage：Power factor switching definite value is setWithWhen loadIt is less thanOr it is higher thanAlso to calculate the actual shortcoming of load or cross what is mended
Reactive power Q, and be compared with the branch road that will put into or the to be cut off actual compensation capacity under current fundamental voltage, such as
After fruit inputOr after excisionThen allow to act, it is then inactive to be unsatisfactory for above-mentioned condition
Make.
In order to adapt to more users requirement, can be adjusted as needed for different or special loads in the step (1)
Whole measured overtone order.
In order to obtain I in the step (4)Ph.0And IPh.1Amplitude and angle of two phasors on same time shaft, it is necessary to
, using system side USFundamental voltage US1Reference data of the angle as the harmonic current angle of measurement.
When being finely divided in the step (5) to low order Large Copacity filter branch group, it the capacity such as can use, by 8:4:2:
The method of 1 coding or both mixing is grouped, and controller adapts to.
Preferably, controller is put into power factor and approached in the step (6)State.
Beneficial effects of the present invention：This, which can exclude background harmonic voltage, influences to detect the detection method of true filter effect,
The Current Voltage of fundamental wave can be detected and power parameter and selectively detect predetermined each harmonic voltage x current, and according to
Each filter branch parameter and current each harmonic voltage calculate the overcurrent-overvoltage coefficient of each input filter branch capacitor, so as to
Unreasonable method of the total harmonic distortion that substitution all uses at present as protection definite value.Can detection user it is unloaded and
The predetermined individual harmonic current parameter of PCC points is flowed through during the whole filter branch of fully loaded lower input, according to measurement result meter twice
Calculate user and exclude the actual filter effect that background harmonic voltage influences.Controller allows to segment Large Copacity low order filter branch
For multiple branch roads, ensure filtering and reactive-load compensation effect in load wide variation.Controller can be thrown according to each branch road
The change for cutting front and rear System Reactive Power calculates the actual capacitance after the branch road capacitor volume reduction, corrects its capacitor parameters,
Ensure correct detection overcurrent-overvoltage coefficient.
The patented technology of the present invention can be not only used for the compensating controller of tuning filtering, can be used for anti-tuning filtering to control again
Device, its capacitor over-current overvoltage detection technique can be additionally used in ordinary capacitor compensating controller.
Brief description of the drawings
The equivalent circuit that accompanying drawing 1 is made when being and background harmonic voltage be present according to low-pressure side voltage；
Accompanying drawing 2 is the schematic diagram according to the principle of stacking in circuit counting to Fig. 1 circuit decoupled methods；Wherein figure (a) is
Background harmonic voltage UShSchematic diagram during independent role, figure (b) is Load harmonic electric current IFhSchematic diagram during independent role.
Accompanying drawing 3 is fundamental voltage US1With fundamental current IS1And fundamental wave busbar voltage UM1Measuring principle figure, wherein (a) is
Schematic diagram during zero load input, schematic diagram when (b) is fully loaded input, load has not been Z on bus hereL1, but ZLF1,
It is ZL1With load impedance of fundamental frequency ZF1Parallel impedance.How this brief description of the drawings obtains U in two pacing amountsS1Amplitude and angle
Degree, and with US1Angle on the basis of, by second step measure IPh.1Gone on the time shaft that reduction measures to the first step.
Accompanying drawing 4 is ISh、IPh.0And IPh.1Between phasor relation figure；
Accompanying drawing 5 be using on the basis of fundamental voltage angle calculate individual harmonic current Angle Method schematic diagram, it is humorous with 5 times
Exemplified by ripple, wherein：(a) it is fundamental voltage U1With 5 subharmonic voltage U5Graph of a relation between same abscissa upper angle；(b) it is
In T0Moment, to fundamental voltage and 5 subharmonic current I5.0Carry out sample graph；(c) it is in T1It is moment, humorous to fundamental voltage and 5 times
Ripple electric current I5.1Carry out sample graph.
Embodiment
To describe the technology contents of the present invention in detail, realizing target effect, it is explained in detail below in conjunction with embodiment.
The present embodiment, which provides a kind of background harmonic voltage that can exclude, to be influenceed to detect the detection method of true filter effect, is implemented
Step is as follows：
(1) harmonic wave of corresponding different numbers reads sampled data using different address pointer table：Corresponding 2,3,4,5,7,
11st, 13,17,19,23,25 times each times harmonic is separately provided a particular sample data address pointer table, form
It is to calculate and be used as in fixed array write-in program according to Fourier's Computing Principle, by the address pointer of form from hits
Sampled data is directly read in, calculates the harmonic parameters of corresponding number, so as to eliminate in fast Flourier butterfly computation
Sequence calculates one after another, time-consuming to shorten dramatically although program code is longer, can basis for different or special loads
Need to adjust measured overtone order；.
(2) overcurrent-overvoltage of detection filter branch road filter capacitor：By each branch road capacitor and the input control of reactor parameter
Device processed, the parameter of capacitor include the specified total capacity Q of three-phaseCeWith rated voltage UCe, the parameter of reactor includes the filtering of this branch road
Number h, the amplification coefficient K of reactorL, X shared by D.C. resistanceLK reciprocalR.Controller calculates equivalence according to capacitor parameters
The single-phase fundamental capacitive reactance X of Y wiringC=UCe 2/QCe；According to XCCalculate the fundamental wave induction reactance X of reactorL=KL*XC/h2；D.C. resistance
R=XL/KR；And calculate the h subharmonic impedance Zs of each branch roadLh=[(h*XL-XC/h)2+R2]0.5；(h=1,2,3 ... 25),
Wherein h=1 is fundamental wave parameter, and remaining h parameter is predetermined each harmonic with practical value, it is described below herewith.
Quickly calculated for ease of CPU, by harmonic impedance ZLhIt is transformed to harmonic admittance YLh=1/ZLh；R, X of each branch roadL、XCAnd admittance
YLhIt is stored in as definite value in CPU.
Controller it is measurable go out bus on fundamental wave and each harmonic phase voltage Uh, then each harmonic of filter branch is flowed through
Electric current ILh=Uh*YLh, and then calculate individual harmonic current caused each harmonic pressure drop U on the capacitorCh=ILh*XC/
h.Flow through total virtual value electric current I of capacitorCRMS=[Σ (ILh 2)]0.5, Σ (I in formulaLh 2) represent individual harmonic current square it
With excessively stream coefficient GLxs=ICRMS/ICE；Total phase voltage that capacitor is born is UCΣ=Σ (UCh), Σ (U in formulaCh) represent
Each harmonic phase voltage sum, over-pressed coefficient Gyxs=√ 3UCΣ/UCE；Here ICEAnd UCEIt is the corresponding volume of capacitor respectively
Determine electric current and rated line voltage.The overcurrent-overvoltage coefficient of capacitor is only the accurate definite value of capacitor protection；
(3) volume reduction of detection filter capacitor：For it is each can independent switching loop, in each input and excision
Each measurement for carrying out single compensation capacity and record.Sensing capacitor can be reached using the change of reactive power and reactive current
The purpose of volume reduction, but it is slightly simple using reactive current program, take slightly shorter.By using exemplified by reactive current, it is assumed that put into certain
System Reactive Power electric current is I before filter branchQO, fundamental wave phase voltage is U1O, after input moment be changed into IQNAnd U1N, input moment bear
The impedance parameter of lotus is constant, then in new voltage U1NOriginal I downQOStrain as IQON=QO*U1N/U1O, the actual reactive current of system
Change turn to Δ IQ=IQN- IQON；The actual fundamental wave admittance Y of the filter branch newly put into can then be calculatedL1N=Δ IQ/U1N, this
In U1NIt is fundamental wave phase voltage, the detection process of excision is the inverse process of input.
Controller all carries out admittance measurement and record in each switching to the branch road of action, the result repeatedly measured again and
Originally the definite value stored compares, and illustrates it must is that capacitance reduces if diminishing, because reactor parameter will not change.Subtract
The computational methods of capacity after small：First by new admittance YL1NIt is changed into impedance parameter ZL1N=1/YL1N, there is what is stored to be somebody's turn to do originally
Road R and XL, it is assumed that new capacitive reactance is XCN, because ZL1N=[(XL-XCN)2+R2]0.5, by XCNAs unknown number, One- place 2-th Order side is solved
Journey can obtain XCN；Then with original R, XLWith new XCNRecalculate the new fundamental wave admittance Y of the branch roadL1NHarmonious waveguide admittance
YLhN, the new foundation as detections such as its overcurrent-overvoltages.
(4) influence of the background harmonic voltage to filter effect is removed：Referring to the drawings 1, this is made according to low-pressure side voltage
The equivalent circuit diagram gone out.Z in figureShIt is fundamental wave and each harmonic impedance of transformer, ZLhIt is total after all filter branch parallel connections
Fundamental wave and each harmonic impedance；UShIt is system background harmonic voltage, IFhIt is individual harmonic current caused by load.Wherein USh
Caused harmonic current IShFlow through ZShInto ZLh；And Load harmonic electric current IFhMost of IFLhFlow into filter branch ZLh, it is remaining
Lower part IFShFlow through ZShEnter system with PCC points, and that power supply department needs to examine is exactly IFSh.It is humorous that background is not present in user
During wave voltage, IPCC=IFShIf IPCC≤Ihi(permissible value of i-th of user's individual harmonic current), then illustrate that user filters effect
Fruit is up to standard.When background harmonic voltage be present in user, IPCC=IFSh+ISh, due to IShPresence, can typically cause IPCCIt is much larger than
IFSh, cause the underproof illusion of filter effect, especially 5 background harmonic voltage USh, may 1% containing ratio will make detection
As a result it is significantly exceeded！Directly result in the state of it background harmonic voltage be present, power supply department can not examine user truly to filter
Effect.
Accompanying drawing 2 is the schematic diagram for carrying out frequency analysis calculating to accompanying drawing 1 using principle of stacking.Wherein (a) be voltage source i.e.
Background harmonic voltage UShIndependent role schematic diagram, caused harmonic current IPh.0∠θPh.0Flow through ZShInto ZLh；Figure (b) is electricity
Stream source is Load harmonic electric current independent role schematic diagram, Load harmonic electric current IFhMost of IFLhAbsorbed by filter branch, it is remaining
Part
IFSh∠θFSh=IFh∠θFh*ZLh∠θFSh/(ZLh∠θFSh+ZSh∠θSh), it flows through PCC points and enters system.According to
Principle of stacking, flow through the harmonic current of PCC points
IPh.1∠θPh.1=IPh.0∠θPh.0+IFSh∠θFSh；
It is the graph of a relation between these three phasors referring to the drawings 4.So
IFSh∠θFSh=IPh.1∠θPh.1-IPh.0∠θPh.0………………(4-1)
As long as it can thus be appreciated that can accurate measurement to IPh.0∠θPh.0And IFSh∠θFSh, just can accurately calculate removal background
The real I of user after harmonic effectsFSh∠θFSh。
Accompanying drawing 1 is user's filter branch schematic diagram under input state entirely at full capacity, can only be measured in this case
IPh.1, and IPh.0And IFShIt can not measure at all.So it can only measure in two steps：
Whole filter branch are put under first step Light Condition, are equivalent to (a) of accompanying drawing 2, measurable IPh.0∠θPh.0；
Second step puts into whole filter branch in a fully loaded state, is equivalent to accompanying drawing 1, measurable IPh.1∠θPh.1.The mesh of two pacing amounts
, the amplitudes of two harmonic currents is not only obtained, also to obtain the relative angle of two harmonic currents.It is due to measuring twice
What artificial random times started, so harmonic current angle measured twice is wide of the mark, in order that two angles
" correlation ", the angle measured twice must have one it is stable and accurate refer to angle, by they to refer to angle relative angle,
And draw the relative angle between them.And reference quantity the most stable in system only has the U of system fundamental voltage i.e. PCC pointsS1。
So in measuring twice, " necessary " also to measure bus-i.e. the fundamental voltage U of M pointsM1∠θUM1, and flow through bus
Fundamental current IM1∠θIM1.Because controller is arranged on M points, M point busbar voltages and fundamental current can only be measured, and PCC points also every
Transformer impedance of fundamental frequency ZS1∠θZS1, a pressure drop Δ U can be produced on it1=IM1∠θIM1*ZS1∠θZS1, and US1∠
θUS1=UM1∠θUM1+ΔU1, transformer impedance Z is flowed through during due to measuring twiceS1Current amplitude and angle be different from, so
The fundamental voltage and electric current of bus will be measured twice, so as to the fundamental voltage U of PCC points when accurately calculating each measurementS1。
According to principles above, measurement for the first time obtains IPh.0∠θPh.0And US1.0∠θUS1.0, measure obtain I for the second timePh.1∠
θPh.1And US1.1∠θUS1.1.In order to illustrate how that the relative angle between harmonic current is drawn on the basis of fundamental voltage angle,
Referring to referring to accompanying drawing 5, by taking 5 subharmonic voltage electric currents as an example, (a) indicates the fundamental voltage U on same time shaft in figure1With 5
Subharmonic voltage U5Relative angular relationship, in 180 ° of fundamental voltage, the angle of 5 subharmonic voltages is 900 °, that is, the time
A certain segment length is fundamental wave angle, θ on axle1, then 5 subharmonic angle, θs corresponding to it5=5* θ1.If h subharmonic, then h times it is humorous
Ripple angle, θh=h* θ1.(b) is in T in accompanying drawing0Moment is to 5 subharmonic current I5.0Sampled, moment θ1.0=36 °, and
θ5.0=30 °；(c) it is in T1Moment is to I5.1Sampled, moment θ1.1=72 °, and θ5.1=90 °；It can be seen that I5.0With
I5.1, between angular difference be not 90 ° -30 °=60 °！Therefore calculating harmonic current must be according to relative to the angle of fundamental voltage
The time shaft of harmonic current calculates, so, first time measurement result IPh.0To US1.0Angle, θh1.0=θPh.0-h*θUS1.0, second
Secondary measurement result IPh.1To US1.1Angle, θh1.1=θPh.1-h*θUS1.1.For accompanying drawing 5, θ51.0=θP5.0-5*θUS1.0=
30 ° -5*36 °=- 150 °；θ51.1=θP5.1-5*θUS1.1=90 ° -5*72 °=- 270 °；So IP5.0To IP5.1Relative angular difference
For θ5=θ51.0-θ51.1=120 °, this really I that can be seen that on the diagram5.0Advanced I5.1For 120 °.This step is calculated with regard to energy
I is calculated with formula (4-1)FSh∠θFSh, but to make θPh.0=0；θPh.1=θh1.1, i.e. IFSh∠θFSh=IPh.1∠θh1.1-
IPh.0∠0。
Scene sometimes for the related each harmonic current of analysis angle and its harmonic voltage angle, and it and
Relation or harmonic power flow direction of fundamental voltage angle etc., so should be come out in measuring twice together with harmonic voltage angular surveying,
Finally measurement result reduction twice is calculated to analysis on same time shaft.Below according to by second of measurement result reduction to
Carry out analysis calculation method on the time shaft of one-shot measurement：
First time measurement result is US1.0∠θUS1.0And IPh.0∠θPh.0, second of measurement result is US1.1∠θUS1.1With
IPh.1∠θPh.1；The angular difference Δ θ of fundamental voltage is calculated first1=θUS1.1-θUS1.0, then it is converted to harmonic wave angle delta θh=h* Δs
θ1, then it is θ on the time shaft of the harmonic current angle reduction of second of measurement to first time measurementPh.1N=θPh.1-Δθh, finally
Calculate IFSh∠θFSh=IPh.1N∠θPh.1-IPh.0∠θPh.0.This method equivalent in accompanying drawing 5 in T0Moment is simultaneously to IPh.0With
IPh.1The result measured.It is to the example calculations result in accompanying drawing 5 according to said method：US1.036 ° of ∠, IPh.030 ° of ∠, IPh.1
∠-90°.It is identical that the rule of harmonic voltage angle calculate method harmonic current angle rule calculation method.
Due to being required in survey calculation twice according to bus fundamental voltage, fundamental current and transformer impedance ZS1Calculate
PCC dot system fundamental voltages, so controller input transformer parameter and must calculate impedance of fundamental frequency ZS1∠θZS1。
(5) controller is finely divided the control mode of group to low order Large Copacity filter branch：Allow user by 5 times or together with
It is finely divided for 7 times for several loops, such as in order to which minimum packets capacity disclosure satisfy that normal minimum load input, 5 total capacities
For 330KVAR, be subdivided into 30,60,120,120KVAR.No matter when the branch road of controller always preferential switching Large Copacity,
Because this can comparatively fast balance it is idle, it is especially larger in idle breach, when 5 subharmonic currents are larger, first put into Large Copacity branch road ratio
The overcurrent-overvoltage pressure for putting into low capacity branch road capacitor is smaller.Controller using power factor as switching definite value, with input be
Example, when detecting power factor less than input definite value, calculated first according to current active power from current power factor
How many reactive capability Q can be accommodated between excision power factor definite valuemax, then from the Large Copacity having not been put to low capacity
Branch road, calculate the branch road to be put into reactive power Q caused by energy under current fundamental voltageB, only QB<QmaxIn the case of just permit
Perhaps put into, so as to avoid switching repeatedly and be stepped up according to coded system from minimum capacity to maximum capacity repeatedly dynamic
Make.Above-mentioned packet mode is 1:2:4:4 hybrid coding modes, be also suitable for wait capacity packet, such as 110,110,110kVAR.
It is grouped and acts according to endless form Deng capacity, in hybrid coding mode, waits capacity portions to be acted by endless form.
(6) flexible switching definite value is set and coordinated with overcurrent-overvoltage：Two sets of power factor switching definite values are setWithThe scope of second set of definite value is wider.Such as first setSecond setWork as load under normal circumstances
'sIt is less thanOr it is higher thanController will judge according to the method in specific implementation (5) and action.
In particular cases.Such as not yet finished after 5 filter branch are grouped, a High Power Factor higher harmonic current has been put into suddenly
Load so that the capacitors of 5 branch roads put into produces overcurrent-overvoltage, if cosq1 definite values will be exceeded by continuing input,
At this moment second set of definite value is used automatically, as long as being no more than after inputCan is put into, and alleviation, which has put into branch road and crossed, to be flowed through
Pressure pressure.For using A.C. contactor as switch, the speed of input can be more severe according to inverse time lag mode, i.e. overcurrent-overvoltage
It is faster to put into speed.
Specific embodiment：
In the present embodiment, why the embodiment (1) will calculate 2,3,4 subharmonic parameters, be because, if
2,3,4 subharmonic occur when having powerful one-way commutation bridge or three-phase commutation bridge to break down in user；And for conventional
The filter based on 5,7,11,13 filter branch for, occurring 2,3,4 inferior low-order harmonic voltages on bus, have can
Some filter branch can be caused to produce serious overcurrent-overvoltage.
Such as certain 7 filter branch, capacitor 350kVAR/525V, KL=1.10, KR=40, can calculate it 2,
3rd, 4,5,7 subharmonic admittance YLh, as shown in table (1), if bus harmonic voltage is Uh, then its electric current I is flowed throughLh=Uh*YLh, can
Although it is 7 filter branch to see it, 2,3,4,5 subharmonic currents can be flowed through in the same old way, then see its admittance radian, in addition to 7 times
All it is "+" value, shows to these low orders
Table (1)：The each harmonic admittance Y of 7 filter branchLh
| Overtone order | 2 | 3 | 4 | 5 | 7 |
| Admittance modulus value | 2.79023 | 4.77407 | 7.92635 | 14.4700 | 88.8203 |
| Admittance radian | 1.56956 | 1.56869 | 1.56720 | 1.56440 | -1.53153 |
Capacitive reactances is presented in harmonic wave, i.e., not only filters but also amplify harmonic wave.
In the present embodiment, in the step (2), in order to detect each filter branch capacitor over-current overvoltage coefficient, it is necessary to defeated
Access customer filter branch initial parameter, controller will calculate the fundamental wave harmony waveguide admittance of each branch road according to this, and according on bus
Fundamental wave and each harmonic voltage calculate the fundamental wave for flowing through capacitor and individual harmonic current and on the capacitor caused base
Ripple and each harmonic voltage drop, so as to calculate the overcurrent-overvoltage coefficient of each branch road capacitor.
Such as certain user sets 5,7,11 three filter branch, capacity QCeRespectively 400,200 and 160kVAR, voltage
UCeAll it is 560V, KLAll it is 1.15, KRAll it is 40, shown in each branch road fundamental wave and each harmonic admittance such as table (2-1)：In table (2-
2) the bus fundamental wave measured and each harmonic phase voltage U are listed inhWhen the individual harmonic current that flows through of each branch road；In table
Caused voltage drop on each branch road capacitor is listed in (2-3).The final overcurrent-overvoltage coefficient for calculating capacitor.Below
Because 23 and 25 subharmonic voltages are zero in embodiment, only calculate to 19 subharmonic parameters.
Table (2-1)：The modulus value Y of each branch road each harmonic admittanceLh：H=1 is defined as fundamental wave
| H | Fundamental wave 1 | 5 | 7 | 11 | 13 | 17 | 19 |
| 5 YL5.h | 1.33701 | 42.4858 | 7.11993 | 3.07283 | 2.44783 | 1.76376 | 1.55291 |
| 7 YL7.h | 0.65308 | 7.71586 | 29.7508 | 3.81307 | 2.79597 | 1.87489 | 1.62160 |
| 11 YL11.h | 0.51510 | 3.34605 | 6.68431 | 37.4093 | 10.9413 | 4.96564 | 3.98762 |
Table (2-2) is under bus fundamental wave and each harmonic phase voltage Uh (V), each branch road individual harmonic current (A),
| h | Fundamental wave 1 | 5 | 7 | 11 | 13 | 17 | 19 |
| Bus Uh (V) | 224.589 | 5.92916 | 3.99769 | 2.51540 | 2.51540 | 1.59458 | 1.39245 |
| 5 IC5.h(A) | 300.278 | 251.905 | 28.4632 | 7.72940 | 6.15727 | 2.81246 | 2.16235 |
| 7 IC7.h(A) | 146.675 | 45.7485 | 118.934 | 9.59138 | 7.03046 | 2.98966 | 2.25800 |
| 11 IC11.h(A) | 115.686 | 19.8393 | 26.7218 | 94.0994 | 27.5216 | 7.91812 | 5.55257 |
Each branch current virtual value：Irms5=393.121A；Irms7=194.698A；Irms11=155.552A；
Each branch road excessively stream coefficient：GLxs5=95.3267%；GLxs7=94.4236%；GLxs11=94.2986%；
Each branch road individual harmonic current of table (2-3) caused phase voltage pressure drop (V) on capacitor C
| h | Fundamental wave 1 | 5 | 7 | 11 | 13 | 17 | 19 |
| 5 UC5.h(V) | 235.418 | 39.4987 | 3.18788 | 0.55090 | 0.37133 | 0.12970 | 0.08923 |
| 7 UC7.h(V) | 229.987 | 14.3467 | 26.6413 | 1.36721 | 0.84798 | 0.27575 | 0.18634 |
| 11 U11.h(V) | 226.744 | 7.77699 | 7.48210 | 16.7668 | 4.14941 | 0.91291 | 0.57279 |
Each branch road capacitor pressure drop superposition value is maximum peak pressure：
Phase voltage peak value：UC5=279.246V；UC7=273.652V；UC11=264.405V；
Each branch road capacitor overvoltage coefficient：GYxs5=86.3694%；GYxs7=84.6392%；GYxs11=
81.7792%；
Controller described above can calculate each branch road harmonic admittance according to the parameter of user's filter branch, and according to survey
The bus harmonic voltage measured calculates the overcurrent-overvoltage coefficient of capacitor.The important meaning of the present invention has three：First, can be with
Exclude in a manner of unreasonable using total harmonic distortion THDu as capacitor protection definite value, reasonable accurately electric capacity can be obtained
Device protected mode；Second, after low order Large Copacity filter branch is subdivided into several each branch roads, it is not necessary to worry so-called equal flow problem, i.e.,
Each branch current should be proportional to its condenser capacity, even if but as long as uneven flow each branch road overcurrent-overvoltage in safe range with regard to energy
Normal operation；Third, controller can handle the delay of subsequent action according to overcurrent-overvoltage degree using inverse time lag mode, it is so-called
Inverse time lag is exactly that overcurrent-overvoltage degree more responsiveness is faster, including needs the speed of trip protection, including has put into branch road
Producing overcurrent-overvoltage needs to put into the input speed that follow-up homogeneous filter branch alleviation has put into branch pressure.
In the present embodiment, in the step (3), the detection method of filter branch capacitor volume reduction is illustrated.Such as certain use
The filter branch of family 5 times is equally divided into 4 each branch roads, and each branch road configures 180kVAR/525V capacitors, KLAll it is 1.10, KRAll it is
40, it can calculate shown in each branch road harmonic admittance such as table (3-1)；
Table (3-1)：Originally 4 branch road harmonic admittance YLhEqually, it is as shown in the table
| Overtone order h | 1 fundamental wave | 5 | 7 | 11 | 13 | 17 | 19 |
| Admittance modulus value | 0.6831177 | 32.603737 | 3.9544315 | 1.6613414 | 1.3191065 | 0.9475946 | 0.8336565 |
In the case where above-mentioned 4 branch road does not have volume reduction state.The detection data of input process, as shown in table (3-2)
Table (3-2)：Progressively put into (progressively excision result is identical) YL1
| Put into way | 0 | 1 | 2 | 3 | 4 |
| Put into capacity | ----------- | 5 times, 180 | 5 times, 180 | 5 times, 180 | 5 times, 180 |
| The Y of inputL1 | 0.0000000 | 0.6831179 | 0.6831179 | 0.6831179 | 0.6831179 |
| IQN | 1188.9493 | 1038.7556 | 887.68274 | 735.72296 | 582.86914 |
| U1O | 224.28770 | 224.28770 | 224.94193 | 225.59981 | 226.26147 |
| U1N | 224.28770 | 224.94193 | 225.59981 | 226.26147 | 226.92694 |
| IQO | -------- | 1188.9493 | 1038.7556 | 887.68274 | 735.72296 |
| IQON | -------- | 1192.4175 | 1041.7937 | 890.28625 | 734.88684 |
| ΔIQ | -------- | 153.99187 | 154.11096 | 154.56329 | 155.01770 |
| The Y of calculatingL1N | 0.0000000 | 0.6831179 | 0.6831166 | 0.6831180 | 0.6831172 |
Each row are parameters measured when putting into this branch road in table, include the admittance definite value Y of input branch roadL1, it is
Reactive current I before and after system inputQOAnd IQN, bus fundamental voltage U before and after input1OAnd U1N, I is calculated by above parameterQON=QO*
U1N/U1O, the change of the actual reactive current of system turns to Δ IQ=IQN- IQON；Then the fundamental wave admittance Y actually measured is calculatedL1N
=Δ IQ/U1N.The detection process of excision is identical with the detection process of input, and result is the same.
If find that the 2nd road and the 3rd roadbed waveguide admittance survey calculation value are Y in detectionL1N.2=0.6617505, YL1N.3=
0.5871775, it is respectively X by the capacitive reactance for calculating two branch roads already less than definite value 0.6831177C2.N=1.5786090,
XC3.N=1.7704368；Condenser capacity is reduced to 174.6 and 167.4kVAR respectively.Controller is counted again according to new capacity
Calculate the harmonic admittance of this two-way.Table (3-3) is each road harmonic admittance together with the first via common list of no volume reduction, facilitates ratio
Compared with.
Table (3-3)：The fundamental wave on the 1st~3 tunnel and each harmonic admittance
| Overtone order h | 1 fundamental wave | 5 | 7 | 11 | 13 | 17 | 19 |
| YL1.h | 0.6831177 | 32.603737 | 3.9544315 | 1.6613414 | 1.3191065 | 0.9475946 | 0.8336565 |
| YL2.h | 0.6617505 | 47.124588 | 4.0631332 | 1.6733099 | 1.3254759 | 0.9501028 | 0.8353924 |
| YL3.h | 0.5871775 | 57.822273 | 4.5722170 | 1.7236058 | 1.3519176 | 0.9603991 | 0.8424983 |
By table (3-3) it can be found that although the fundamental wave admittance on 2~3 tunnels reduce it is few, but harmonic admittance-especially they
5 admittance changes filtered out are very big, and are increased and a lot, illustrate their filter effect " having got well a lot ", as a result
5 subharmonic currents for causing them to filter out greatly increase, and overcurrent-overvoltage coefficient greatly increases.So only measured by volume reduction,
Their harmonic admittance could be corrected, accomplishes the correctness of capacitor over-voltage and over-current detection.
In the present embodiment, in the step (4), when in the absence of system background harmonic voltage, directly in the detection of PCC points just
The real filter effect I of user can be obtainedFSh.And when background harmonic voltage be present in system, it is necessary to be carried out in two steps measurement.One
Typically with the example of the measurement true filter effect of 5 subharmonic currents：
Known transformer impedance of fundamental frequency ZS1∠θZS1=0.0045000 ∠ 1.3680097；5 background harmonic voltages of system
US5=5.7735023V, equivalent to 5 subharmonic voltage containing ratio HRU5=2.522%：
It is unloaded for the first time to put into whole filter branch, measure：
Flow through PCC 5 subharmonic current IP5.0∠θP5.0=190.53708 ∠ 0.1048521；Flow through the fundamental wave electricity of bus
Flow IM1.0∠θIM1.0=1124.2328 ∠ 2.1937623, bus fundamental voltage UM1.0∠θUM1.0=233.87158 ∠
0.6238486；Calculate fundamental current IM1.0∠θIM1.0In ZS1Pressure drop dU caused by upper1.0=5.0590472 ∠ -2.7214134,
And then calculate system fundamental voltage US1.0=228.91942 ∠ 0.6283185；
Second of fully loaded whole filter branch of input, is measured：
Flow through PCC 5 subharmonic current IP5.1∠θP5.1=203.25096 ∠ 2.3037069；Flow through the fundamental wave electricity of bus
Flow IM1.1∠θIM1.1=1992.7046 ∠ 1.1149846, bus fundamental voltage UM1.1∠θUM1.1=226.95750 ∠
1.1135274；Fundamental current I is calculatedM1.1∠θIM1.1In ZS1Pressure drop dU caused by upper1.1=8.9671707 ∠
2.4829943 and then calculate system fundamental voltage US1.1=228.91937 ∠ 1.1519173；
Controller in order to by second of measurement result reduction to first time measurement time shaft on, first calculate measurement base twice
Wave voltage US1Angular difference, Δ θ1=θUS1.1-θUS1.0=1.1519173-0.6283185=0.5235988, then 5 subharmonic angular difference
Δθ5=5* Δs θ1=2.6179941.Then by IP5.1∠θP5.1Angle subtract Δ θ5, reduction is obtained to first time time shaft
IP5.1N∠θP5.1N=203.20596 ∠ -0.3124872.
Finally calculated according to formula (4-1)：
IFS5∠θFS5=IP5.1N∠θP5.1N-IP5.0∠θP5.0=82.861740 ∠ -1.5248671.
Result of calculation illustrates that 5 subharmonic currents that PCC points are actually entered after user's filtering are only 82.861740A, and
The 5 subharmonic current 203.25096A that PCC points measure differ greatly.
In the present embodiment, why group is finely divided to low order Large Copacity filter branch in the step (5), is because using
The low order filter branch capacity at family is excessive, can not be put into normal Smaller load.Such as certain subharmonic current of user 5,7,11 contains
There is rate HRi={ 16,11,7 } %；Fundamental current 1800A, then individual harmonic current is { 288,198,126 } (A)；Regular filtering
Device manufacturer can design in accordance with the following methods：First calculate three COEFFICIENT Ksh=Ih/h：K5=288/5=57.6；K7=198/
7=28.29；K11=126/11=11.45；Then K=K5+K7+K11=97.34.Reactive power if necessary to compensation is Q=
1000kVAR/400V, then each secondary branch road compensation capacity be about：5 Q5=Q*K5/ K=592, Q7=Q*K7/ K=291；Q11=
Q*K11/ K=118；
If using 560V capacitors, Qh.1=Qh*5602/4002=1.96Qh；Then Q5.1=1160；Q7.1=570；
Q11.1=231.Be respectively finally 900 by suitably adjusting each appearance of a street amount, 660,360kVAR.Can be with average mark for 5 branch roads
For 300+300+300,180+360+360 can also be divided into, 82+164+328+328 can also be divided into.It is grouped anyway in a word
Controller can adapt to；Plus over-voltage and over-current and volume reduction detection can be carried out to each individually branch road, subdivision group more can guarantee that
Safe operation afterwards.
In the present embodiment, in the step (6), if 5 times of user and 7 filter branch have all carried out subdivision group,
When reactive load can only put into 5 branch roads, controller as far as possible can put into 5 branch roads more, allow power factor close to excision definite valueState, main purpose is reduces the harmonic pressure of filter condenser, because the more pressure of input are smaller；If 5 times
All put into, it will be less than when power factorWhen put into 7 branch roads, once 7 branch roads have an input, and throw
Enter consideration the same during 5 branch roads as far as possible can put into 7 branch roads more.
In the present embodiment, in the step (6), to be calculated under current fundamental voltage before throwing or cutting each filter branch action
The actual compensation capacity of the branch road, in order to which controller quickly calculates, it is necessary to calculate a penalty coefficient K of each filter branchQ
=3YL1If current fundamental wave phase voltage is U1, then compensation capacity is QB=KQ*U1 2；Such as certain 5 filter branch has been computed
Go out fundamental wave admittance YL1=0.6831177, then KQ=2.0493531, current fundamental wave phase voltage=230V is measured, then it is sent
Reactive power QB=108.41kVAR.
In the present embodiment, in the step (6), higher harmonic current high power may be put at random in Smaller load operation
The high-power load of factor, such as high-power standard configuration (no input reactance, no filter reactance, no output reactance) frequency converter, it
Power factor>0.97, and THDi>60% so that the capacitor for the filter branch having been put into produces overcurrent-overvoltage.Now if
5 times or 7 filter branch are without all putting into after subdivision group, then should continue input could mitigate the pressure of capacitor, but by
Power factor in it is too high, and the capacity that can be accommodated is too small, and continuing input can causeNeed to set for this
Put second set of switching power factor definite valueWithAnd the second group of scope of definite value than first group is big.Such asAndSuch as load initial parameter is
500kW, 310kVAR, compensation capacity 210kVAR now has been put into, actual power factor 0.9806, has met first set
The requirement of switching definite value, but because harmonic current content is very big, has there is overcurrent-overvoltage in capacitor, and 5 filter branch are still
Do not finish, if according to second set of definite value additional input 210kVAR capacity, power factor can reach -0.9766, and filter
The overcurrent-overvoltage pressure of capacitor can greatly reduce.This state is typically occurred under Smaller load, in peak load highest harmonic wave
Under current status, the design of filter manufacturer, which should ensure that, occurs without above-mentioned condition.And required according to the power rate of regulation,
- 0.9766 is compensated still in the range of reward highest, and thrown one times of filter capacity more, dissolved overcurrent-overvoltage pressure
Power.Other low side power factor is -0.9766, and high-pressure side power factor can be more nearly 1.00, because high-low pressure
Side is across a transformer emotional resistance ZS1, a part of reactive power can be consumed.
In the present embodiment, in the step (6), near power factor 1.00, the little excursion of power factor is just
Very big filter capacity can be accommodated, such as in the range of 0.90~0.95, scope 0.05, the reactive capability of receiving is Q=
0.1556*P, wherein P are active power at that time；In the range of 0.95~1.00, and 0.05 scope, then Q=0.3287*
P；In the range of 0.98~-0.98, then Q=0.4061*P.Last power factor scope is only 0.04, and Q reaches
0.4061*P.Very big filtering can be but put into power factor very little excursion here it is second set of switching definite value is set
Capacity, and then alleviate the principle and method of capacitor over-current overvoltage stress.
The detection method that the true filter effect of background harmonic voltage influence detection can be excluded can detect the electric current of fundamental wave
Voltage and power parameter and predetermined each harmonic voltage x current is selectively detected, and according to each filter branch parameter and worked as
Preceding each harmonic voltage calculates the overcurrent-overvoltage coefficient of each input filter branch capacitor, so as to substitute what is all used at present
Unreasonable method of the total harmonic distortion as protection definite value.Energy detection input all filtering in the case where user is unloaded and fully loaded
The predetermined individual harmonic current parameter of PCC points is flowed through during branch road, it is humorous to calculate user's exclusion background according to measurement result twice
The actual filter effect that wave voltage influences.Controller allows Large Copacity low order filter branch being subdivided into multiple branch roads, in load
Ensure filtering and reactive-load compensation effect during wide variation.Controller can be according to the change of System Reactive Power before and after each branch road switching
Change calculates the actual capacitance after the branch road capacitor volume reduction, corrects its capacitor parameters, ensures that correct detected is flowed through
Press coefficient.I
Embodiments of the invention are the foregoing is only, are not intended to limit the scope of the invention, it is every to utilize this hair
The equivalent transformation that bright specification and accompanying drawing content are made, or other related technical areas are directly or indirectly used in, similarly
It is included within the scope of the present invention.
Claims (6)
1. a kind of background harmonic voltage that can exclude influences to detect the detection method of true filter effect, apply to filtering compensation control
In device, it is characterised in that implementation steps are as follows：
(1) harmonic wave of corresponding different numbers reads sampled data using different address pointer table：Corresponding fundamental wave and 2,3,4,5,
7th, 11,13,17,19,23,25 times each times harmonic is separately provided a particular sample data address pointer table, should
Form is calculated and is used as in fixed array write-in program according to Fourier's Computing Principle, by the address pointer of form from sampling
Sampled data is directly read in data, calculates the harmonic parameters of corresponding number；
(2) overcurrent-overvoltage of detection filter branch road filter capacitor：By each branch road capacitor and reactor parameter input controller,
Controller calculates the fundamental wave capacitive reactance X of capacitorC, reactor fundamental wave induction reactance XLAnd the resistance R of reactor, and calculate each
The fundamental wave and each harmonic admittance Y of branch roadLh, it is stored in as definite value in CPU.Controller can measure bus fundamental wave and each time it is humorous
Ripple phase voltage Uh, then the individual harmonic current I of filter branch is flowed throughh=Uh*YLh, and then individual harmonic current is calculated in electric capacity
Caused harmonic wave pressure drop U on deviceCh=Ih*XC/ h, including the individual harmonic current including fundamental current quadratic sum again
Evolution is exactly the current effective value for flowing through capacitor, divided by rated capacitor electric current is exactly excessively stream coefficient, is wrapped on same capacitor
It is exactly the peak voltage that capacitor is born, peak voltage divided by capacitor to include each harmonic voltage drop sum including fundamental voltage
Rated voltage is exactly over-pressed coefficient, and the overcurrent-overvoltage coefficient of capacitor is only the accurate definite value of capacitor protection；
(3) volume reduction of detection filter capacitor：For it is each can independent switching loop, it is each before and after each action to carry out one
The measurement and amendment of secondary compensation capacity, it is characterised in that every time action before and after will measure record bus fundamental voltage and system without
Work(electric current (or reactive power), and the actual fundamental wave admittance Y of the branch road is calculated accordinglyL1N, repeatedly measure obtained YL1NDefinite value again
In YL1Compare, the illustrated capacitor volume reduction if diminishing, controller is according to YL1NCalculate the X after volume reductionCN, and it is and former
Come the X storedLThe Y of the branch road is recalculated with RLhN, and with new YLhNFoundation as the measurement of overcurrent-overvoltage coefficient；
(4) influence of the background harmonic voltage to filter effect is removed：When background harmonic voltage is not present in user, produced by load
A harmonic current part be to flow into filter branch ZLhIFLh, remainder IFShSystem, i.e. I are flowed into by PCC pointsPCC=
IFShIf IPCC≤Ihi, then illustrate that user's filter effect is up to standard.Background harmonic voltage U be present in userShWhen, if for the first time
Whole filter branch, i.e. U are put under load Light ConditionShAct solely on ZLhWhen, flow through the electric current I of PCC pointsPh.0=ISh,
And IShPurely it is to be caused by the background harmonic voltage of system；Whole filter branch are put under load full load condition for the second time, are carried on the back
Scape harmonic voltage UShWith Load harmonic electric current IFhCollective effect is in ZLhWhen, the electric current for now flowing through PCC points is according to phasor relation
IPh.1=IFSh+ISh, due to IShPresence, can typically cause IPCCMuch larger than IFSh, cause the underproof illusion of filter effect；It is accurate
Really measurement IPh.0And IPh.1The amplitude of two phasors and their relative angle, then draw I by phasor computingFSh, i.e. IFSh=
IPCC-ISh；Exactly need the I examinedhi.Due to being random, measured I at the time of measuring beginning twicePh.0And IPh.1Two
The angle of phasor is also unrelated, must detect the fundamental voltage and fundamental current of bus simultaneously in being measured twice for this, and count
The system for calculating PCC points surveys fundamental voltage US1Angle and base using its angle as the harmonic current angle measured twice
It is accurate.If U twiceS1Angular difference be Δ θ1, then the I that measures twicePh.0And IPh.1Angular difference be Δ θh=h* Δs θ1As long as with Δ θh
Correct any one angle in two vectors, it is possible to by the same time shaft of its reduction to another phasor, so as to accurate
Really calculate IFSh=IPCC-ISh。
(5) group is finely divided to low order Large Copacity filter branch：It is finely divided by 5 times or together with 7 times as several loops, minimum point
Pool-size disclosure satisfy that normal minimum load input；
(6) flexible switching definite value is set and coordinated with overcurrent-overvoltage：Power factor switching definite value is setWithWhen
LoadIt is less thanOr it is higher thanAlso to calculate the actual shortcoming of load or cross the reactive power Q mended,
And and the branch road that will be put into or to be cut off actual compensation capacity under current fundamental voltage is compared, if after inputOr after excisionThen allow to act, be unsatisfactory for above-mentioned condition then akinesia.
2. the background harmonic voltage according to claim 1 that can exclude influences to detect the detection method of true filter effect, its
It is characterised by, measured overtone order can be adjusted in the step (1) as needed for different or special loads.
3. the background harmonic voltage according to claim 1 that can exclude influences to detect the detection method of true filter effect, its
It is characterised by, sensing capacitor volume reduction in the step (3), record bus fundamental voltage will be measured before and after action every time and be
Reactive current of uniting (or reactive power), and the actual fundamental wave admittance Y of the branch road is calculated accordinglyL1NWith each harmonic admittance YLhN。
4. the background harmonic voltage according to claim 1 that can exclude influences to detect the detection method of true filter effect, its
It is characterised by, when being detected using zero load input and the fully loaded whole filter branch of input, it is necessary to survey fundamental voltage U with systemS1Angle
Spend the reference data of the harmonic current angle as measurement.
5. the background harmonic voltage according to claim 1 that can exclude influences to detect the detection method of true filter effect, its
It is characterised by, controller allows user to be finely divided group to low order Large Copacity filter branch in the step (5), can use etc.
Capacity, by 8:4:2:The method of 1 coding or both mixing is grouped.
6. the background harmonic voltage according to claim 1 that can exclude influences to detect the detection method of true filter effect, its
It is characterised by, controller is put into power factor and approached in the step (6)State.
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| CN111832243A (en) * | 2020-07-25 | 2020-10-27 | 无锡特力堡电气有限公司 | Design simulation tool and method for introducing passive filtering compensation of actually measured electric energy parameters |
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