CN107026465A - Mixing double-fed enters the computational methods in flexible direct current steady-state operation region in straight-flow system - Google Patents

Mixing double-fed enters the computational methods in flexible direct current steady-state operation region in straight-flow system Download PDF

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CN107026465A
CN107026465A CN201710348347.9A CN201710348347A CN107026465A CN 107026465 A CN107026465 A CN 107026465A CN 201710348347 A CN201710348347 A CN 201710348347A CN 107026465 A CN107026465 A CN 107026465A
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hvdc
vsc
subsystems
power
operating point
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CN107026465B (en
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郭春义
陆翌
童凯
赵成勇
刘炜
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North China Electric Power University
Electric Power Research Institute of State Grid Zhejiang Electric Power Co Ltd
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North China Electric Power University
Electric Power Research Institute of State Grid Zhejiang Electric Power Co Ltd
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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
    • 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
    • H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
    • H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • 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
    • H02J2003/365—Reducing harmonics or oscillations in HVDC
    • 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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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention belongs to transmission ＆ distribution electro-technical field, more particularly to a kind of mixing double-fed enters the computational methods in flexible direct current steady-state operation region in straight-flow system, the maximum active power, maximum reactive power and its broad sense traffic coverage for allowing to exchange between VSC HVDC subsystems and AC system are determined；Scan the operating point of VSC HVDC subsystems in broad sense traffic coverage, and calculate ac bus voltage magnitude and phase angle to judge whether operating point meets the trend constraint condition of VSC HVDC subsystems, solution specific blend double-fed enters the subsystem power output under straight-flow system operating mode after satisfaction, 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 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

Mixing double-fed enters the computational methods in flexible direct current steady-state operation region in straight-flow system
Technical field
Enter flexible direct current stable state in straight-flow system the invention belongs to transmission ＆ distribution electro-technical field, more particularly to a kind of mixing double-fed The computational methods of operation area.
Background technology
Based on line commutation converter type D.C. high voltage transmission (line commutated converter based high Voltage direct current, LCC-HVDC) it has been widely used in long-distance and large-capacity power transmission occasion, and based on voltage Source converter type D.C. high voltage transmission (voltage source converter based high voltage direct Current, VSC-HVDC) technology quickly grows in recent years.VSC-HVDC has active reactive power independent control, independent of friendship The technical advantages such as streaming system operation, VSC-HVDC is introduced into Multi-infeed HVDC transmission system, and composition mixing multi-infeed HVDC is defeated Electric system is to improve multi-infeed HVDC system characteristic one of study hotspot as academia.
Mix by a LCC-HVDC and VSC-HVDC compositions exemplified by double-fed enters straight-flow system, because LCC-HVDC is sub Electrical distance is nearer between system and VSC-HVDC subsystems, there are electrical couplings between the two, VSC-HVDC subsystems it is steady State operation area is influenceed to change by LCC-HVDC subsystems, therefore need to be calculated the mixing double-fed under different operating modes and entered directly The steady-state operation of VSC-HVDC subsystems is interval in streaming system, and how fast and effectively to calculate steady-state operation region needs as current The problem of solving.
The content of the invention
In view of the above-mentioned problems, the present invention, which provides a kind of mixing double-fed, enters flexible direct current steady-state operation region in straight-flow system Computational methods, including：
Step one：Determine the maximum active-power P for allowing to exchange between VSC-HVDC subsystems and AC systems2maxMost Big reactive power Qs2max, so that it is determined that broad sense the traffic coverage [- P of VSC-HVDC subsystemss2max≤Ps2≤Ps2max,-Qs2max≤ Qs2≤Qs2max], Ps2、Qs2The respectively active power and reactive power of VSC-HVDC subsystems；
Step 2：Scan the operating point (P of VSC-HVDC subsystems in broad sense traffic coverages2,Qs2), according to VSC-HVDC Subsystem operating point (Ps2,Qs2) calculate VSC-HVDC subsystem ac bus voltage magnitudes V2With phase angle δ2, obtained according to calculating Ac bus voltage V2∠δ2Judge operating point (Ps2,Qs2) the trend constraint conditions of VSC-HVDC subsystems whether is met, such as Fruit, which meets, then enters step 3, otherwise scans next group of operating point；
Step 3：Straight-flow system steady-state load flow equation group and VSC-HVDC operating points (P are entered according to mixing double-feds2,Qs2), Solution specific blend double-fed enters the VSC-HVDC subsystem power outputs under straight-flow system operating mode, and judges VSC-HVDC subsystems The active-power P of outputd2And reactive power Qd2Whether safe operation constraint, if met if operating point (P are metd2,Qd2) for institute The operating point in flexible direct current steady-state operation interval in mixing double feed-in d. c. power transmission system is sought, otherwise return to step two；
Step 4：Judge the operating point (P in broad sense traffic coverages2,Qs2) whether scanned, if scanned Then export all VSC-HVDC operating points (P for meeting conditiond2,Qd2) traffic coverage that is constituted is required mixing double-fed Enter flexible direct current steady-state operation in DC transmission system interval, 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 mixing double-fed and propose a kind of to determine that its flexible direct current is steady The computational methods of state operation area, can quickly and efficiently calculate the operation area for determining VSC-HVDC subsystems under different operating modes.
Brief description of the drawings
Fig. 1 enters the computational methods flow chart that flexible direct current stable state in straight-flow system transports region to determine to mix double-fed.
Fig. 2 enters straight-flow system model schematic for mixing double-fed.
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：Determine the maximum active-power P for allowing to exchange between VSC-HVDC subsystems and AC systems2max With maximum reactive power Qs2max, so that it is determined that broad sense the traffic coverage [- P of VSC-HVDC subsystemss2max≤Ps2≤Ps2max,- Qs2max≤Qs2≤Qs2max], wherein：
Wherein V2For VSC-HVDC subsystem ac bus voltage modulus value；Vs2For the equivalent electromotive force of AC system 2, Zs2To hand over The equivalent impedance of streaming system 2, Xs2、Rs2For the equivalent reactance of AC system 2 and substitutional resistance.
(2) step 2：Scan VSC-HVDC subsystem operating points (P in broad sense operation areas2,Qs2), according to VSC-HVDC Subsystem operating point (Ps2,Qs2) calculate VSC-HVDC subsystem ac bus voltage magnitudes V2With phase angle δ2, obtained according to calculating Ac bus voltage V2∠δ2Judge operating point (Ps2,Qs2) the trend constraint conditions of VSC-HVDC subsystems whether is met, tool Body process is as follows：
The active-power P of AC system is injected according to VSC-HVDC subsystemss2And reactive power Qs2, and by ac bus Voltage is expressed as V2∠δ2=v2d+jv2q, then ac bus voltage V2∠δ2With AC system voltage Vs2∠α2Between relation root According to being represented by：
The d axis components and q axis components for obtaining ac bus voltage can be calculated by formula (3)：
VSC-HVDC subsystems 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：Double-fed is mixed according to Fig. 2 and enters the distribution of straight-flow system model trend and mix double-fed to enter direct current system Known conditions of uniting solves the active-power P of VSC-HVDC subsystems transmissiond2And reactive power Qd2, detailed process is as follows：
Mixing double-fed can be listed according to Fig. 2 and enter straight-flow system power flow equation：
Wherein Pd1,Qd1The active power and reactive power exported for LCC-HVDC subsystems, when LCC-HVDC rectification sides are fixed DC current controller keeps DC current Id1For Idref, it is γ that inverter side, which determines hold-off angle control device to maintain to turn off angle γ,refWhen, The power of LCC-HVDC subsystems output is represented by:
Wherein Ud10For the preferable floating voltage in LCC valves side, T1For LCC converter power transformer no-load voltage ratios, N is LCC current conversion stations per in extremely 6 pulse conversion devices numbers.
Pc1,Qc1And Pc2,Qc2The active power and nothing respectively consumed on LCC reactive power compensators and VSC alternating current filters Work(power, is represented by：
Z in formulac1,θc1And Zc2,θc2The respectively equivalent impedance and equivalence of LCC reactive power compensators and VSC alternating current filters Impedance angle.
The power P that LCC-HVDC subsystems are transmitted to AC system 1s1,Qs1It is represented by：
Z in formulas1,θs1Equivalent impedance and equivalent impedance angle for AC system 1, Vs1, α1It is equivalent electronic for AC system 1 The amplitude and phase angle of gesture, V1,δ1For LCC-HVDC subsystem ac bus voltage magnitudes and phase angle.
The power P that VSC-HVDC subsystems are transmitted to AC system 2s2,Qs2It is represented by：
Z in formulas2,θs2Equivalent impedance and equivalent impedance angle for AC system 2, Vs2, α2It is equivalent electronic for AC system 2 The amplitude and phase angle of gesture, V2,δ2For VSC-HVDC subsystem ac bus voltage magnitudes and phase angle.
The active-power P that LCC-HVDC is transmitted to VSC-HVDC on interconnectiontie1And reactive power Qtie1It is represented by：
Z in formulatie,θs2For interconnection equivalent impedance and equivalent impedance angle.
The active-power P that VSC-HVDC is transmitted to LCC-HVDC on interconnectiontie2And reactive power Qtie2It is represented by：
The power P of VSC-HVDC transmissiond2, 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 (13) is substituted into formula (6), and according to known conditions：1) mixing double-fed enters VSC-HVDC subsystems in straight-flow system The equivalent electromotive force V of AC system 2 connecteds2∠α2It is known；2) LCC- is kept when mixing double-fed enters straight-flow system steady-state operation HVDC subsystem ac bus voltage V1Amplitude is rated value V1n；3) power from VSC-HVDC subsystems to AC system feed-in (Ps2,Qs2) known；4) active-power P transmitted on interconnection is assumedtie1(or reactive power Qtie1) obtained, it is known that can solve VSC-HVDC subsystem power outputs Pd2And Qd2, and judge the active-power P of VSC-HVDC subsystems outputd2And reactive power Qd2Whether safe operation constraint is met：
1) variation is constrained
To ensure VSC-HVDC subsystem ac bus voltages within the deviation range of permission, ac bus voltage magnitude V2Need to meet：
V2min≤V2≤V2max (13)
Wherein V2minTypically take 0.95pu, V2maxTypically 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 VcAlso need to meet modulation ratio constraint：
U in formulad2For VSC-HVDC subsystem DC voltages.
Operating point (the P if safe operation constraint is metd2,Qd2) mix soft in double feed-in d. c. power transmission system to be required Operating point in property DC Steady traffic coverage, otherwise return to step two.
(4) step 4：Judge the operating point (P in broad sense traffic coverages2,Qs2) whether scanned, if scanned through All VSC-HVDC operating points (P for meeting condition of Bi Ze outputsd2,Qd2) traffic coverage that is constituted is that required mixing is double Flexible direct current steady-state operation is interval in infeed HVDC Systems, 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. a kind of mix the computational methods that double-fed enters flexible direct current steady-state operation region in straight-flow system, it is characterised in that including：
Step one：Determine the maximum active-power P for allowing to exchange between VSC-HVDC subsystems and AC systems2maxWith maximum nothing Work(power Qs2max, so that it is determined that broad sense the traffic coverage [- P of VSC-HVDC subsystemss2max≤Ps2≤Ps2max,-Qs2max≤Qs2≤ Qs2max], Ps2、Qs2The respectively active power and reactive power of VSC-HVDC subsystems；
Step 2：Scan the operating point (P of VSC-HVDC subsystems in broad sense traffic coverages2,Qs2), according to VSC-HVDC subsystems Operating point (Ps2,Qs2) calculate VSC-HVDC subsystem ac bus voltage magnitudes V2With phase angle δ2, the exchange obtained according to calculating Busbar voltage V2∠δ2Judge operating point (Ps2,Qs2) the trend constraint condition of VSC-HVDC subsystems whether is met, if met Then enter step 3, otherwise scan next group of operating point；
Step 3：Straight-flow system steady-state load flow equation group and VSC-HVDC operating points (P are entered according to mixing double-feds2,Qs2), solve special Surely mixing double-fed enters the VSC-HVDC subsystem power outputs under straight-flow system operating mode, and judges the output of VSC-HVDC subsystems Active-power Pd2And reactive power Qd2Whether safe operation constraint, if met if operating point (P are metd2,Qd2) mixed to be required Operating point in double feed-in d. c. power transmission system in flexible direct current steady-state operation interval, otherwise return to step two；
Step 4：Judge the operating point (P in broad sense traffic coverages2,Qs2) 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 enters direct current Flexible direct current steady-state operation is interval in 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.
CN201710348347.9A 2017-05-17 2017-05-17 Method for calculating flexible direct current steady state operation area in hybrid double-feed-in direct current system Active CN107026465B (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108110784A (en) * 2018-01-10 2018-06-01 重庆大学 Reduce the control method that mixing double-fed enters operation risk under straight-flow system electric network fault
CN113176428A (en) * 2021-03-16 2021-07-27 上海交通大学 Current distortion eliminating system and method for working condition simulation of cascaded converter
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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Publication number Priority date Publication date Assignee Title
CN105119316A (en) * 2015-08-31 2015-12-02 上海交通大学 VSC-MTDC (Voltage source converter-multi-terminal high voltage direct current) voltage control method for offshore wind farm integration
CN105762808A (en) * 2016-04-07 2016-07-13 国网福建省电力有限公司 Power grid flow online optimization control method based on flexible DC transmission technology
CN105958485A (en) * 2016-06-14 2016-09-21 中国电力科学研究院 Power flow calculation method for flexible interconnecting alternating current-direct current hybrid power distribution network
CN106655199A (en) * 2017-01-24 2017-05-10 国网福建省电力有限公司 VSC-HVDC power control method for improving voltage stability

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105119316A (en) * 2015-08-31 2015-12-02 上海交通大学 VSC-MTDC (Voltage source converter-multi-terminal high voltage direct current) voltage control method for offshore wind farm integration
CN105762808A (en) * 2016-04-07 2016-07-13 国网福建省电力有限公司 Power grid flow online optimization control method based on flexible DC transmission technology
CN105958485A (en) * 2016-06-14 2016-09-21 中国电力科学研究院 Power flow calculation method for flexible interconnecting alternating current-direct current hybrid power distribution network
CN106655199A (en) * 2017-01-24 2017-05-10 国网福建省电力有限公司 VSC-HVDC power control method for improving voltage stability

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108110784A (en) * 2018-01-10 2018-06-01 重庆大学 Reduce the control method that mixing double-fed enters operation risk under straight-flow system electric network fault
CN113176428A (en) * 2021-03-16 2021-07-27 上海交通大学 Current distortion eliminating system and method for working condition simulation of cascaded converter
CN113176428B (en) * 2021-03-16 2022-05-03 上海交通大学 Current distortion eliminating system and method for working condition simulation of cascaded converter
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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