CN107171352A - The interval computational methods of flexible direct current steady-state operation in mixed DC system arranged side by side - Google Patents
The interval computational methods of flexible direct current steady-state operation in mixed DC system arranged side by side Download PDFInfo
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- CN107171352A CN107171352A CN201710349151.1A CN201710349151A CN107171352A CN 107171352 A CN107171352 A CN 107171352A CN 201710349151 A CN201710349151 A CN 201710349151A CN 107171352 A CN107171352 A CN 107171352A
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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
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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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
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The invention belongs to transmission ＆ distribution electro-technical field, more particularly to the interval computational methods of flexible direct current steady-state operation in a kind of mixed DC system arranged side by side, it is determined that mixing double-fed in parallel enters the maximum active power, maximum reactive power and its broad sense traffic coverage for allowing to exchange between straight-flow system and AC system；Mixing double-fed in parallel enters the operating point of straight-flow system in scanning broad sense traffic coverage, and calculate ac bus voltage magnitude and phase angle to judge whether operating point meets the trend constraint condition that mixing double-fed in parallel enters straight-flow system, VSC HVDC are solved after satisfaction to AC system transimission power, and judge whether to meet safe operation constraint, the operating point is the operating point in flexible direct current steady-state operation interval in required mixing double feed-in d. c. power transmission system in parallel if meeting, exported if scanned the traffic coverage that all operating points for meeting condition are constituted be in required mixing double feed-in d. c. power transmission system flexible direct current steady-state operation it is interval.
Description
Technical field
Transported the invention belongs to flexible direct current stable state in transmission ＆ distribution electro-technical field, more particularly to a kind of mixed DC system arranged side by side
The interval computational methods of row.
Background technology
Presented by line commutation converter type HVDC transmission system and voltage source converter based HVDC system
Enter the mixing double feed-in d. c. power transmission system in parallel of same ac bus voltage composition, you can give full play to LCC-HVDC conveying appearances
Amount is big, the low technical advantage of construction cost, and quick independent of AC network operation, active reactive power using VSC-HVDC
The technical characterstics such as independent control are to improve the operation characteristic of multi-infeed HVDC system.
Because parallel connection mixing double-fed enters VSC-HVDC and the same AC system of LCC-HVDC feed-ins in straight-flow system, and LCC-
The active power and reactive power of HVDC subsystem output are intercoupled, and LCC-HVDC Steadies are held by LCC transverters
The influence of the factor such as amount, LCC converter Controls pattern, AC system intensity is notable, and the change of LCC-HVDC subsystem operation characteristics
The Steady of VSC-HVDC subsystems will be changed by changing, therefore need to be calculated the mixing double-fed in parallel under different operating modes and entered direct current
The steady-state operation of VSC-HVDC subsystems is interval in system, and how fast and effectively to calculate steady-state operation region turns into current needs
The problem of solution.
The content of the invention
In view of the above-mentioned problems, interval the invention provides flexible direct current steady-state operation in a kind of mixed DC system arranged side by side
Computational methods, including：
Step one：It is determined that mixing double-fed in parallel enters the maximum active power for allowing to exchange between straight-flow system and AC system
PsmaxWith maximum reactive power Qsmax, so that it is determined that mixing double-fed in parallel enters broad sense the traffic coverage [- P of straight-flow systemsmax≤Ps
≤Psmax,-Qsmax≤Qs≤Qsmax], Ps、QsMixing double-fed respectively in parallel enters the active power and reactive power of straight-flow system；
Step 2：Mixing double-fed in parallel enters straight-flow system operating point (P in scanning broad sense traffic coverages,Qs), according to parallel connection
Mixing double-fed enters straight-flow system operating point (Ps,Qs) calculate ac bus voltage magnitude UpWith phase angle δp, the friendship obtained according to calculating
Flow busbar voltage Up∠δpJudge operating point (Ps,Qs) the trend constraint condition that mixing double-fed in parallel enters straight-flow system whether is met,
Enter step 3 if meeting, otherwise scan next group of operating point；
Step 3：According to Up∠δpCalculating obtains the active-power P that LCC-HVDC is transmitted to AC systemd1And reactive power
Qd1, and judge to calculate obtained ac bus voltage Up∠δpMixing double-fed in parallel is entered straight-flow system and meet quiescent voltage
Scleronomic constraint condition, enters step 4, otherwise return to step two if meeting；
Step 4：According to ac bus voltage Up∠δpThe active-power P transmitted with LCC-HVDC to AC systemd1, nothing
Work(power Qd1, and mixing double-fed in parallel enters straight-flow system operating point (Ps,Qs) calculate and obtain VSC-HVDC and passed to AC system
Defeated active-power Pd2, reactive power Qd2, judge the active-power P that VSC-HVDC is transmitted to AC systemd2And reactive power Qd2
Whether safe operation constraint, if met if operating point (P are metd2,Qd2) mix double feed-in d. c. power transmission system for required parallel connection
Operating point in middle flexible direct current steady-state operation interval, otherwise return to step two；
Step 5：Judge the operating point (P in broad sense traffic coverages,Qs) whether scanned, if scanned
All VSC-HVDC operating points (P for meeting condition of outputd2,Qd2) traffic coverage that is constituted is that required mixing in parallel is double
Flexible direct current steady-state operation is interval in infeed HVDC Systems, otherwise return to step two.
The safe operation constraint includes：Inverter circuit constraint, modulation ratio constraint, variation constraint.
The beneficial effects of the present invention are：Enter straight-flow system for parallel connection mixing double-fed and propose a kind of to determine that it is flexible straight
The computational methods in steady-state operation region are flowed, the operation for determining VSC-HVDC subsystems under different operating modes can be quickly and efficiently calculated
It is interval.
Brief description of the drawings
Fig. 1 enters flexible direct current steady-state operation interval computation method flow diagram in straight-flow system for mixing double-fed in parallel.
Fig. 2 enters straight-flow system model schematic for mixing double-fed in parallel.
Embodiment
Below in conjunction with the accompanying drawings, embodiment is elaborated.It is the flow chart of this method as shown in Figure 1.
(1) step one：It is determined that mixing double-fed in parallel enters allow to exchange between straight-flow system and AC system maximum active
Power PsmaxWith maximum reactive power Qsmax, so that it is determined that mixing double-fed in parallel enters broad sense the traffic coverage [- P of straight-flow systemsmax
≤Ps≤Psmax,-Qsmax≤Qs≤Qsmax], wherein：
Wherein UpFor ac bus voltage；E is the equivalent electromotive force of AC system, ZsFor AC system equivalent impedance, Xs、Rs
For AC system equivalent reactance and substitutional resistance.
(2) step 2：Mixing double-fed in parallel enters straight-flow system operating point (P in scanning broad sense operation areas,Qs), according to simultaneously
Connection mixing double-fed enters straight-flow system operating point (Ps,Qs) calculate ac bus voltage magnitude UpWith phase angle δp, obtained according to calculating
Ac bus voltage Up∠δpJudge operating point (Ps,Qs) whether meet the trend constraint bar that mixing double-fed in parallel enters straight-flow system
Part, detailed process is as follows：
The active-power P that straight-flow system injects AC system is entered according to mixing double-fedsAnd reactive power Qs, and will exchange mother
Line voltage is expressed as Up∠δp=Upd+jUpq, then ac bus voltage Up∠δpWith the relation root between AC system voltage E ∠ 0
According to being represented by：
The d axis components and q axis components for obtaining ac bus voltage can be calculated by formula (3)：
Mixing double-fed enters straight-flow system need to meet trend constraint to the power of AC system feed-in：
Enter step 3 if trend constraint condition is met, otherwise return to step two；
(3) step 3：LCC-HVDC rectification side constant DC current controls device keeps DC current Id1For Idref, inverter side is fixed
Hold-off angle control device maintains shut-off angle γ to be γref, so that the ac bus voltage U obtained according to calculatingp∠δpIt can calculate and obtain
The power of LCC-HVDC outputs is represented by:
Wherein N is LCC current conversion stations per 6 pulse conversion devices numbers in extremely.
Calculate obtained ac bus voltage Up∠δpMixing double-fed in parallel need to be made to enter straight-flow system and meet static voltage stability
Constraints, can set up mixing double feed-in d. c. power transmission system load flow Jacobian matrix in parallel according to Fig. 2：
Wherein JPδ, JPU, JQδ, JQUFor the element of Jacobian matrix；△ δ, △ U/U are ac bus voltage phase angle and amplitude
Correction；△ P, △ Q are ac bus active power and reactive power correction, are represented by according to Fig. 2：
Wherein △ Ps、△QsFor AC system active power and reactive power correction；△Pd1、△Qd1For LCC-HVDC
System active power and reactive power correction；△Pd2、△Qd2For VSC-HVDC subsystems active power and reactive power amendment
Amount；△Pc、△QcActive power and reactive power correction for reactive power compensator.
LCC-HVDC subsystems alternating current filter is represented by the power of ac bus feed-in：
Wherein ZcFor the equivalent impedance modulus value of reactive power compensator, θcFor reactive power compensator equivalent impedance angle.
According to Fig. 1 VSC-HVDC equivalent circuits, Pd2, Qd2It is represented by again：
Wherein XeqFor VSC-HVDC equivalent reactances, for MMC-HVDC systems Xeq=XT2+XL0/ 2, wherein XL0For bridge arm string
Join reactance；UcAnd δcFor the amplitude and phase angle of VSC inverter output voltages.
Formula (6) and formula (9-10) are substituted into formula (8), and the corresponding member in formula (7) Jacobian matrix is can obtain to its derivation
Element, so that the static voltage stability limits for obtaining mixing double feed-in d. c. power transmission system in parallel are：
Enter to enter step 4 if straight-flow system meets static voltage stability limits condition if parallel connection mixing double-fed, otherwise return
Return step 2.
(4) step 4：According to ac bus voltage Up∠δpThe active-power P transmitted with LCC-HVDC to AC systemd1、
Reactive power Qd1, and mixing double-fed in parallel enters straight-flow system operating point (Ps,Qs) calculate obtain VSC-HVDC to AC system
The active-power P of transmissiond2, reactive power Qd2：
Judge the active-power P that VSC-HVDC is transmitted to AC systemd2And reactive power Qd2Whether safe operation is met about
Beam：
1) variation is constrained
Ac bus voltage to ensure mixing double feed-in d. c. power transmission system exchanges female within the deviation range of permission
Line voltage amplitude UpNeed to meet：
Umin≤Up≤Umax (13)
Wherein UminTypically take 0.95pu, UmaxTypically take 1.05pu.
2) Inverter circuit is constrained
VSC-HVDC operation area need to consider the overcurrent capability that VSC transverters allow, that is, meet Inverter circuit about
Beam condition：
Wherein ImaxThe maximum current allowed to flow through for VSC transverters.
3) modulation ratio is constrained
MMC-HVDC systems for approaching modulator approach using nearest level, overmodulation is operated in for anti-locking system,
MMC inverter output voltages UcAlso need to meet modulation ratio constraint：
Operating point (the P if safe operation constraint is metd2,Qd2) mix double feed-in d. c. power transmission system for required parallel connection
Operating point in middle flexible direct current steady-state operation interval, otherwise return to step two.
(5) step 5：Judge the operating point (P in broad sense traffic coverages,Qs) whether scanned, if scanned
Then export all VSC-HVDC operating points (P for meeting conditiond2,Qd2) traffic coverage that is constituted is required mixing in parallel
Flexible direct current steady-state operation is interval in double feed-in d. c. power transmission system, otherwise return to step two.
Above-described embodiment is only the present invention preferably embodiment, but protection scope of the present invention is not limited to
This, any one skilled in the art the invention discloses technical scope in, the change that can readily occur in or replace
Change, should all be included within the scope of the present invention.Therefore, protection scope of the present invention should be with the protection model of claim
Enclose and be defined.
Claims (2)
1. the interval computational methods of flexible direct current steady-state operation in a kind of mixed DC system arranged side by side, it is characterised in that including：
Step one：It is determined that mixing double-fed in parallel enters the maximum active-power P for allowing to exchange between straight-flow system and AC systemsmax
With maximum reactive power Qsmax, so that it is determined that mixing double-fed in parallel enters broad sense the traffic coverage [- P of straight-flow systemsmax≤Ps≤
Psmax,-Qsmax≤Qs≤Qsmax], Ps、QsMixing double-fed respectively in parallel enters the active power and reactive power of straight-flow system；
Step 2：Mixing double-fed in parallel enters straight-flow system operating point (P in scanning broad sense traffic coverages,Qs), according to parallel connection mixing
Double-fed enters straight-flow system operating point (Ps,Qs) calculate ac bus voltage magnitude UpWith phase angle δp, it is female according to the exchange that calculating is obtained
Line voltage Up∠δpJudge operating point (Ps,Qs) the trend constraint condition that mixing double-fed in parallel enters straight-flow system whether is met, if
Meet and then enter step 3, otherwise scan next group of operating point；
Step 3：According to Up∠δpCalculating obtains the active-power P that LCC-HVDC is transmitted to AC systemd1And reactive power Qd1,
And judge to calculate obtained ac bus voltage Up∠δpMixing double-fed in parallel is entered straight-flow system and meet static voltage stability
Constraints, enters step 4, otherwise return to step two if meeting；
Step 4：According to ac bus voltage Up∠δpThe active-power P transmitted with LCC-HVDC to AC systemd1, reactive power
Qd1, and mixing double-fed in parallel enters straight-flow system operating point (Ps,Qs) calculate obtain VSC-HVDC to having that AC system is transmitted
Work(power Pd2, reactive power Qd2, judge the active-power P that VSC-HVDC is transmitted to AC systemd2And reactive power Qd2It is whether full
Sufficient safe operation constraint, the operating point (P if meetingd2,Qd2) mix flexible in double feed-in d. c. power transmission system for required parallel connection
Operating point in DC Steady traffic coverage, otherwise return to step two；
Step 5：Judge the operating point (P in broad sense traffic coverages,Qs) whether scanned, exported if scanned
All VSC-HVDC operating points (P for meeting conditiond2,Qd2) traffic coverage that is constituted is that required mixing double-fed in parallel enters
Flexible direct current steady-state operation is interval in DC transmission system, otherwise return to step two.
2. method according to claim 1, it is characterised in that the safe operation constraint includes：Inverter circuit constraint, tune
System is than constraint, variation constraint.
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| CN201710349151.1A CN107171352B (en) | 2017-05-17 | 2017-05-17 | Method for calculating stable running interval of flexible direct current in parallel hybrid direct current system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112054546A (en) * | 2019-06-05 | 2020-12-08 | 西安许继电力电子技术有限公司 | Power coordination method and device for multi-drop-point hybrid direct-current power transmission system and storage medium |
| CN113452060A (en) * | 2021-06-09 | 2021-09-28 | 华中科技大学 | Method and system for analyzing stable operation interval of VSC-LCC cascaded hybrid direct current system |
| CN115663876A (en) * | 2022-10-25 | 2023-01-31 | 国网经济技术研究院有限公司 | Method and system for designing main loop parameters of hybrid cascade extra-high voltage direct current system |
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Cited By (5)
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| CN112054546A (en) * | 2019-06-05 | 2020-12-08 | 西安许继电力电子技术有限公司 | Power coordination method and device for multi-drop-point hybrid direct-current power transmission system and storage medium |
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| CN113452060A (en) * | 2021-06-09 | 2021-09-28 | 华中科技大学 | Method and system for analyzing stable operation interval of VSC-LCC cascaded hybrid direct current system |
| CN113452060B (en) * | 2021-06-09 | 2022-08-02 | 华中科技大学 | Method and system for analyzing stable operation interval of VSC-LCC cascaded hybrid direct current system |
| CN115663876A (en) * | 2022-10-25 | 2023-01-31 | 国网经济技术研究院有限公司 | Method and system for designing main loop parameters of hybrid cascade extra-high voltage direct current system |
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