CN106981880A - In a kind of distribution system at point of common coupling uneven responsibility quantitative calculation method - Google Patents
In a kind of distribution system at point of common coupling uneven responsibility quantitative calculation method Download PDFInfo
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- CN106981880A CN106981880A CN201710408798.7A CN201710408798A CN106981880A CN 106981880 A CN106981880 A CN 106981880A CN 201710408798 A CN201710408798 A CN 201710408798A CN 106981880 A CN106981880 A CN 106981880A
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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
- H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase 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
- Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks
Abstract
The invention discloses the quantitative calculation method of uneven responsibility at point of common coupling in a kind of distribution system, comprise the following steps：Step 1, set up in distribution system at point of common coupling the quantitative calculating of uneven responsibility equivalent circuit diagram；Step 2, when imbalance is entirely from system side, calculate the relation obtained between the voltage and current unbalance factor of system point of common coupling；Step 3, when imbalance is entirely from user side, calculate the relation obtained between the voltage and current unbalance factor of system point of common coupling；Step 4, the uneven contribution quantitative values for obtaining system side and user side；Step 5, the main uneven disturbing source for identifying system point of common coupling.Three-phase voltage, current data and the load capacity that point of common coupling measurement that can be in system is obtained effectively calculate the ration contribution of uneven disturbing source in distribution system and identify the position of main uneven disturbing source.
Description
Technical field
The present invention relates to main uneven disturbing source identification technology field, more particularly to public coupling in a kind of distribution system
The quantitative calculation method of uneven responsibility at point.
Background technology
In power system, three-phase voltage complete equipilibrium in the ideal case.The amplitude of three-phase voltage is equal, and phase angle is successively
120 degree of difference.However, the virtual voltage of system is generally uneven, reason has a lot, such as the uneven distribution of threephase load, three
Phase load is uneven, asymmetric transfer impedance and asymmetrical Transformer Winding impedance etc..Due to large capacity single phase load number
The increase of amount, energy imbalance compared to becoming increasingly severe in the past.Imbalance of three-phase voltage can be led in power system
Cause many detrimental effects.For example, unbalanced supply voltage will threaten the security and economy of Operation of Electric Systems.For
Some electric power terminal devices, such as induction machine and adjustable-speed driver, the influence of Voltage unbalance are also more serious.Particularly, such as
The uneven degree of fruit supply voltage is more than 2.5%, and some electronic equipments are likely to be broken.Therefore, it can be seen that the balance of voltage
To the importance of power system.Therefore, International Electrotechnical Commission has delivered a report for being directed to three-phase imbalance standard：IEC/
TR61000-3-13-2008.This report is pointed out, when the PCC Voltage unbalances under normal running conditions exceed setting, to find out
Main uneven source is the prerequisite of imbalance mitigation measure.
With the propulsion of energy conservation and polymorphic type, renewable energy power generation technology and high-speed railway will welcome the height of development
Tide, wind-power electricity generation, solar power generation, substantial amounts of nonlinear-load accesses power network, and a series of voltage imbalance will certainly be brought to ask
Topic.Meanwhile, present industrial production and life automaticity scale is very high, and the mass dependence to voltage is higher, therefore is
Reduce inconvenience and economic loss that supply voltage imbalance is brought, it is necessary to Voltage unbalance is furtherd investigate, looked for
To main Voltage unbalance source, the responsibility of Voltage unbalance contribution is specified, rational slow down is implemented to main uneven source and arranged
Apply, safe and stable supply voltage is finally provided for Electricity customers, be power department increase benefit, be the safe operation of power network
Necessary ensure is provided.
The content of the invention
The invention aims to solve the above problems to blame there is provided uneven at point of common coupling in a kind of distribution system
The quantitative calculation method appointed, three-phase voltage that point of common coupling measurement that can be in system is obtained, current data and bears
Lotus capacity effectively recognizes in distribution system the position of main imbalance disturbing source, and quantifies calculating its harmonic contributions.
To achieve these goals, the present invention is adopted the following technical scheme that：
In a kind of distribution system at point of common coupling uneven responsibility quantitative calculation method, comprise the following steps：
Step 1, set up in distribution system at point of common coupling the quantitative calculating of uneven responsibility equivalent circuit diagram；
Step 2, when imbalance is entirely from system side, calculate and obtain the voltage and current of point of common coupling in system
Relation between unbalance factor；
Step 3, when imbalance is entirely from user side, calculate and obtain the voltage and current of point of common coupling in system
Relation between unbalance factor；
Step 4, the uneven contribution quantitative values for obtaining system side and user side；
Step 5, the main uneven disturbing source for identifying system point of common coupling.
Equivalent circuit diagram in the step 1 includes three branch roads between common point and ground, and every branch road is corresponded to respectively
The equivalent unbalance voltage source of system side of the phase, system side equiva lent impedance, load are sequentially connected in series on A, B, C three-phase, every branch road
Equiva lent impedance.
In the step 2, user side load is the mixing load that passive load and induction-motor load are constituted, in systems
It is in parallel at point of common coupling.
The specific method of the step 2 is：
Step 2.1, the point of common coupling represented using the intrinsic relation existed between electric current, impedance and voltage in system
The forward-order current and negative-sequence current at place；
Step 2.2, the positive and negative sequence impedance of passive load are equal, therefore carry out abbreviation to the relation in step 2.1,
Obtain the relation between Voltage unbalance rate and current imbalance rate；
Step 2.3, with the capacity of load represent the relation between Voltage unbalance rate and current imbalance rate.
In the step 3, when imbalance is entirely from user side, the equivalent negative sequence voltage source of system side is 0.
The specific method of the step 3 is：
Step 3.1, according to the equivalent circuit obtained in step 1, be using the relation between voltage, electric current and impedance
Positive sequence voltage and negative sequence voltage in system at point of common coupling；
Step 3.2, the equivalent negative sequence voltage source of system side are 0, therefore carry out abbreviation to the formula in step 3.1, are obtained
The relation of Voltage unbalance rate and current imbalance rate；
Step 3.3, with the capacity of load represent the relation between Voltage unbalance rate and current imbalance rate.
The specific method of the step 4 is；
Step 4.1, make in the same coordinate system at system point of common coupling in the case of two kinds of step 2 and step 3
Relation curve between voltage and current unbalance factor, abscissa is current imbalance rate, and ordinate is Voltage unbalance rate；
Step 4.2, actual Voltage unbalance rate ε is marked out in the accompanying drawingsU；
Step 4.3, corresponding actual current unbalance factor marked out according to virtual voltage unbalance factor, mark out actual electricity
Flow the Voltage unbalance rate at the corresponding system point of common coupling in the case of two kinds of step 2 and step 3 of unbalance factorWith
Step 4.4, calculating obtain system side imbalance contribution SUC and user side imbalance contribution CUC.
The specific method of the step 4.4 is：
According to formula S UC=DeltC/(DeltS+DeltC) × 100% calculates system side imbalance contribution SUC, wherein
DeltCRepresent εUWithThe distance between, DeltSRepresent εUWithThe distance between；
According to formula CUC=DeltS/(DeltS+DeltC) × 100% calculates user side imbalance contribution CUC.
The specific method of the step 5 is：
Work as SUC>>During CUC, main imbalance disturbing source is in system side；
As SUC ＜ ＜ CUC, main imbalance disturbing source is in user side.
Beneficial effects of the present invention：
(1) three-phase voltage, current data and load capacity that point of common coupling measurement that can be in system is obtained
The position of main uneven disturbing source effectively in identification distribution system；
(2) based on the imbalance research under two kinds of different situations, the system side under actual conditions and user can be calculated
The uneven contribution of side, method simple practical.
(3) according to the size of imbalance contribution, based on will the identification of uneven disturbing source provide the standard of a quantization,
The position of main uneven disturbing source can fast and accurately be identified.
Brief description of the drawings
Fig. 1 is the flow chart of the inventive method.
Fig. 2 is equivalent circuit diagram of the invention.
The schematic diagram that Fig. 3 quantitatively calculates for the present invention.
Fig. 4 is the one-line diagram of the present embodiment.
Uneven contribution comparison diagram that Fig. 5 calculates for the present invention and based on emulation.
Embodiment
The present invention is further illustrated with embodiment below in conjunction with the accompanying drawings.
As shown in figure 1, the present invention proposes a kind of quantitative calculating of uneven responsibility at point of common coupling in distribution system
Method, idiographic flow is as follows：
1st, set up for uneven responsibility is quantitatively calculated at point of common coupling in distribution system equivalent circuit diagram.
As shown in Fig. 2 the equivalent circuit diagram of the quantitative calculating of uneven responsibility at point of common coupling in distribution system is set up,
The three-phase imbalance voltage source of system side is equivalent toThe three-phase equivalent impedance of system side is ZSA, ZSB, ZSC,
PCC (Point of Common Coupling) is the point of common coupling in system,Represent the A phases at PCC points
Voltage-to-ground, B phase-to-ground voltages, C phase-to-ground voltages, ZLA, ZLB, ZLCRepresent A respectively, B, the equiva lent impedance of C three-phase loads,A phases, B phases and C phase currents are represented respectively.
2nd, obtain when imbalance is entirely from system side, the voltage and current unbalance factor of system point of common coupling it
Between relation.
To Fig. 2 circuit analysis is carried out to understand, when imbalance is entirely from system side, user side load be passive load and
The mixing load of induction-motor load composition, the parallel connection PCC at, therefore forward-order current and negative-sequence current at PCC points are represented by：
WhereinFor the positive sequence voltage at PCC points,For the negative sequence voltage at PCC points,For the positive sequence electricity at PCC points
Stream,For the negative-sequence current at PCC points, Z1_IMFor the positive sequence impedance of three phase induction motor, Z2_IMFor three phase induction motor
Negative sequence impedance, Z1_PLFor the positive sequence impedance of passive load, Z2_PLFor the negative sequence impedance of passive load.It is positive and negative due to passive load
Sequence impedance is equal, i.e. Z1_PL=Z2_PL, therefore above formula is simplified, obtain Voltage unbalance rate and current imbalance rate
Between relation：
WhereinBe imbalance entirely from system side, Voltage unbalance rate when load is mixing load,For electricity
Flow unbalance factor.
In order that expression formula can be showed with the capacity of load, formula is simplified, be can obtain：
Wherein kIMThe ratio of positive sequence impedance and negative sequence impedance for three phase induction motor,For being total to for load total capacity
Yoke,For the conjugation of passive load capacity.
3rd, obtain when imbalance is entirely from user side, the voltage and current unbalance factor of system point of common coupling it
Between relation.
As shown in Fig. 2 when imbalance is entirely from the state that user side load, system side are complete equipilibriums, PCC points
Positive sequence voltage and negative sequence voltage be：
WhereinFor the equivalent positive sequence voltage source of system side,For the equivalent negative sequence voltage source of system side, due to all
Imbalance both be from user side, soThe relation that can obtain Voltage unbalance rate and current imbalance rate is：
WhereinVoltage unbalance rate during for imbalance entirely from user side load,Represent system side positive sequence
Equivalent voltage source,The forward-order current at PCC is represented,Represent the negative-sequence current at PCC, ZSSRepresent the equivalent from resistance of system side
It is anti-, ZSMRepresent the equivalent mutual impedance of system side.
4th, the uneven contribution quantitative values of system side and user side are obtained.
As shown in figure 3, its described step (4) is, it is different entirely from two kinds of system side and user side according to imbalance
The calculation formula of situation, obtains the relation between current imbalance rate and Voltage unbalance rate, as shown in Figure 3.In actual conditions
In, actual Voltage unbalance rate can fall between both limiting cases, the C points in such as Fig. 3, be labeled as εU.Work as imbalance
During entirely from system side, the A points in Voltage unbalance rate such as Fig. 3 are labeled asWhen imbalance is entirely from user side
When, the B points in Voltage unbalance rate such as Fig. 3 are labeled asIn order to define the uneven contribution of system side and user side, so：
Wherein DeltSRepresent εUWithThe distance between, DeltCRepresent εUWithThe distance between.
Therefore system side imbalance contribution (SUC), which can be obtained, is：SUC=DeltC/(DeltS+DeltC) × 100%；
User side imbalance contribution (CUC) be：CUC=DeltS/(DeltS+DeltC) × 100%；
5th, the main uneven disturbing source of system point of common coupling is identified.
The contribution of system side imbalance and user side imbalance contribution obtained according to calculating, it is uneven by comparison system side
Contribution judges the position of main uneven disturbing source with the size of user side imbalance contribution；
As SUC ＞ ＞ CUC, illustrate that main uneven disturbing source is in system side；
As SUC ＜ ＜ CUC, illustrate that main uneven disturbing source is in user side.
Embodiment：
The system schematic of the present embodiment is as shown in Figure 4.Wherein, PCC points are points of common connection,For electric power system etc.
Threshold voltage source, ZSystemFor the equivalent impedance of system side, ZLineFor line impedance, ZPLRepresent passive load, ZIMRepresent three-phase induction
Induction-motor load.
The basic parameter of Fig. 4 systems is：
Electric power system：10kV, 50Hz, phase three-wire three
System impedance：ZSystem=(0.0365+j0.1966) Ω
Transmission line of electricity：Length is 5km, and line impedance matrix (per km) is：
Passive load：Total capacity is 5MVA, and power factor is 0.95
Induction motor load：Total capacity is 2.4MVA
The parameter of induction conductivity：6.0kV,200kW,50Hz,Rs=0.0464p.u., Xs=0.0585p.u., Rr=
0.0132p.u.,Xr=0.0585p.u., Xm=1.2056p.u. and J=398.0kg/m2.
Change the degree of unbalancedness of load and equivalent electric power system respectively, obtain one and obtained with method proposed by the present invention
Uneven contribution margin, then the uneven contribution margin obtained with emulation mode are contrasted.
Case 1：
The degree of unbalancedness of user side keeps constant, and the load capacity for setting A phases is 90%, the B phases and C phases of rated capacity
Capacity is rated capacity, produces 6 sub- examples by changing the amplitude of system side A phase voltages, excursion for (0.95,
1.00) p.u., amplitude of variation is each 0.01p.u., and the amplitude of B phases and C phases keeps constant.
Case 2：
The degree of unbalancedness of system side keeps constant, and the amplitude for setting A phase voltages source is 0.95, the B phases and C phases of rated value
Voltage source amplitude is rated value.6 sub- examples are produced by changing the capacity of A phase loads, excursion is (0.75,1.0)
P.u., amplitude of variation is each 0.05p.u., and the load capacity of B phases and C phases is rated value.
Constituted for load under the mixing load condition for passive load and three phase induction motor load, case 1 is obtained
Result it is as shown in table 1：
Table 1
The result that case 2 is obtained is as shown in table 2：
Table 2
The method that case 1 and case 2 are carried by the present invention is calculated and emulation result of the comparison is as shown in Figure 5.
Although above-mentioned the embodiment of the present invention is described with reference to accompanying drawing, not to present invention protection model
The limitation enclosed, one of ordinary skill in the art should be understood that on the basis of technical scheme those skilled in the art are not
Need to pay various modifications or deform still within protection scope of the present invention that creative work can make.
Claims (9)
1. in a kind of distribution system at point of common coupling uneven responsibility quantitative calculation method, it is characterized in that, including following step
Suddenly：
Step 1, set up in distribution system at point of common coupling the quantitative calculating of uneven responsibility equivalent circuit diagram；
Step 2, when imbalance is entirely from system side, calculate obtain point of common coupling in system voltage and current it is uneven
Relation between weighing apparatus rate；
Step 3, when imbalance is entirely from user side, calculate obtain point of common coupling in system voltage and current it is uneven
Relation between weighing apparatus rate；
Step 4, the uneven contribution quantitative values for obtaining system side and user side；
Step 5, the main uneven disturbing source for identifying system point of common coupling.
2. in a kind of distribution system as claimed in claim 1 at point of common coupling uneven responsibility quantitative calculation method, it is special
Levying is, the equivalent circuit diagram in the step 1 includes three branch roads between common point and ground, every branch road difference corresponding A, B,
The equivalent unbalance voltage source of system side of the phase, system side equiva lent impedance, load are sequentially connected in series on C three-phases, every branch road equivalent
Impedance, is the point of common coupling in system between system side equiva lent impedance and load equiva lent impedance.
3. in a kind of distribution system as claimed in claim 1 at point of common coupling uneven responsibility quantitative calculation method, it is special
Levying is, in the step 2, and user side load is the mixing load that passive load and induction-motor load are constituted, public affairs in systems
It is in parallel at Coupling point altogether.
4. in a kind of distribution system as claimed in claim 3 at point of common coupling uneven responsibility quantitative calculation method, it is special
Levying is, the specific method of the step 2 is：
Step 2.1, represented at the point of common coupling in system using the intrinsic relation existed between electric current, impedance and voltage
Forward-order current and negative-sequence current；
Step 2.2, using the positive and negative sequence impedance of passive load it is that the equal relational expression in step 2.1 carries out abbreviation, obtains
Relation between Voltage unbalance rate and current imbalance rate；
Step 2.3, with the capacity of load represent the relation between Voltage unbalance rate and current imbalance rate.
5. in a kind of distribution system as claimed in claim 1 at point of common coupling uneven responsibility quantitative calculation method, it is special
Levying is, in the step 3, when imbalance is entirely from user side, and the equivalent negative sequence voltage source of system side is 0.
6. in a kind of distribution system as claimed in claim 5 at point of common coupling uneven responsibility quantitative calculation method, it is special
Levying is, the specific method of the step 3 is：
Step 3.1, according to the equivalent circuit diagram obtained in step 1, be using the relation between voltage and electric current and impedance
Positive sequence voltage and negative sequence voltage at point of common coupling in system；
Step 3.2, using the equivalent negative sequence voltage source of system side for the formula in 0 pair of step 3.1 abbreviation is carried out, obtain voltage not
The relation of balanced ratio and current imbalance rate；
Step 3.3, with the capacity of load represent the relation between Voltage unbalance rate and current imbalance rate.
7. in a kind of distribution system as claimed in claim 1 at point of common coupling uneven responsibility quantitative calculation method, it is special
Levying is, the specific method of the step 4 is；
Step 4.1, make in the same coordinate system voltage at system point of common coupling in the case of two kinds of step 2 and step 3
Relation curve between current imbalance rate, abscissa is current imbalance rate, and ordinate is Voltage unbalance rate；
Step 4.2, actual Voltage unbalance rate ε is marked out in the accompanying drawingsU；
Step 4.3, corresponding actual current unbalance factor marked out according to virtual voltage unbalance factor, mark out actual current not
Voltage unbalance rate at the corresponding system point of common coupling in the case of two kinds of step 2 and step 3 of balanced ratioWith
Step 4.4, calculating obtain system side imbalance contribution SUC and user side imbalance contribution CUC.
8. in a kind of distribution system as claimed in claim 7 at point of common coupling uneven responsibility quantitative calculation method, it is special
Levying is, the specific method of the step 4.4 is：
According to formula S UC=DeltC/(DeltS+DeltC) × 100% calculates system side imbalance contribution SUC, wherein DeltC
Represent εUWithThe distance between, DeltSRepresent εUWithThe distance between；
According to formula CUC=DeltS/(DeltS+DeltC) × 100% calculates user side imbalance contribution CUC.
9. in a kind of distribution system as claimed in claim 8 at point of common coupling uneven responsibility quantitative calculation method, it is special
Levying is, the specific method of the step 5 is：
Work as SUC>>During CUC, main imbalance disturbing source is in system side；
Work as SUC<<During CUC, main imbalance disturbing source is in user side.
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| CN110135039A (en) * | 2019-05-07 | 2019-08-16 | 国网冀北电力有限公司电力科学研究院 | Wind-powered electricity generation collects regional non-equilibrium among three phase voltages and determines method and device |
| CN110231546A (en) * | 2019-07-19 | 2019-09-13 | 广东电网有限责任公司 | A kind of Fault Section Location of Distribution Network, device and equipment |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110135039A (en) * | 2019-05-07 | 2019-08-16 | 国网冀北电力有限公司电力科学研究院 | Wind-powered electricity generation collects regional non-equilibrium among three phase voltages and determines method and device |
| CN110231546A (en) * | 2019-07-19 | 2019-09-13 | 广东电网有限责任公司 | A kind of Fault Section Location of Distribution Network, device and equipment |
| CN110231546B (en) * | 2019-07-19 | 2022-03-29 | 南方电网电力科技股份有限公司 | Power distribution network fault section positioning method, device and equipment |
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