CN109995053A - A kind of flexible direct current system converter station promotion mains frequency stability control method - Google Patents
A kind of flexible direct current system converter station promotion mains frequency stability control method Download PDFInfo
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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
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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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 present invention relates to a kind of flexible direct current system converter stations to promote mains frequency stability control method, this method is based on direct current frequency limiter FLC control and virtual synchronous control is realized, FLC controlling unit obtains active power regulation increment Delta P needed for MMC carries out frequency support by detection AC network frequency variation and additional frequency feedback control loopFLC.It is characterized in that, obtaining the frequency reference and phase reference of MMC output voltage by the active power controller loop controlled based on virtual synchronous, the voltage magnitude reference of MMC output voltage is obtained by reactive power or alternating voltage control loop；After obtaining output voltage phase reference and amplitude reference, the control of alternating voltage Closed loop track is realized by voltage and current Double-loop Control Strategy.
Description
Technical field
The present invention relates to a kind of promotion mains frequency stability control methods.
Background technique
Flexible DC transmission (voltage source converter based high-voltage DC, VSC-HVDC)
As HVDC Transmission Technology of new generation, because it has the characteristics that power factor is high, control is flexible, effect on environment is small, in the world
Broad development and application have been obtained in range[1-3].The voltage source converter that flexible DC transmission technology generallys use is main
By following form: two level converters, diode-clamped three-level converter and modularization multi-level converter
(modular multilevel converter,MMC).It is compared with two, three-level converter topology, MMC has switching frequency
The low, advantages such as harmonic characterisitic is good and is easy to expand, therefore are used widely in flexible DC transmission[4-6]。
The even asynchronous interconnection of multizone AC system of two regions is realized by flexible DC transmission technology, can be improved transregional
The safety of domain mixing bulk power grid[7].And maintain system frequency stabilization be safe and stable operation of power system main target it
One[8,9].When exchanging side system by load disturbance, system frequency can deviate, and even result in hunting of frequency, influence system
It operates normally.For flexible direct current interacted system, system frequency support is participated in by adjusting direct current system transimission power, to raising
Whole system security and stability has remarkable effect.
Additional frequency support and control method be current VSC-HVDC participate in AC system frequency support main method it
One[10-13].Direct current frequency limiter (Frequency limit controller, FLC) is commonly used to maintain weak AC system side
Frequency stability.Document [14,15] is based on frequency domain and simulation analysis, proposes that the setting dead zone FLC is less than generator primary frequency modulation
The control mode in dead zone solves the frequency periodicity oscillation problem under direct current decoupled mode.Document [16] is to exhale distant engineering
For, it analyzes operation characteristic of the FLC under normal and failure mode in direct current islanded system transmitting system and is controlled with unit, safety
The matching relationship of the various aspects such as system maintains system to stablize.Document [17] proposes through direct current frequency control, cuts machine, unit in high week
The cooperation of frequency modulation and safety stabilization control system realizes the control of sending frequency stabilization.Document [18] combines FLC real
Border control logic is analyzed with acting characteristic, elaborates the matching relationship of FLC and primary frequency modulation, and based on FLC spare capacity,
Influence of the dead time to frequency peak and FLC regulated quantity release process, proposes FLC frequency modulation optimisation strategy, effectively performance FLC
To the inhibiting effect of frequency peak.Direct current transmission power may be implemented controllably by FLC control and system frequency peak value inhibits, but
Damper Braces can not be provided for system, flexible direct current asynchronous interacted system dynamic characteristic of power frequency when improving load disturbance.
Virtual synchronous generator techniques (virtual synchronous generator, VSG) can simulate synchronous generator
The inertial properties and primary frequency modulation characteristic of machine increase system inertia, provide frequency support, therefore obtain extensive concern[19].Document
[20] propose that flexible HVDC transmission system receiving end inverter uses the chirping strategies of virtual synchronous generator VSG technology, by drawing
Enter virtual rotary inertia, so that there is receiving end inverter the Dynamic Inertia of synchronous generator to respond；By simulating synchronous generator
Active-frequency droop static characteristic, realize primary frequency function.Document [21] is virtual from the both ends VSC-HVDC are fully achieved
The angle that synchronously control and two regions mutually support, both ends VSC converter station are all made of the sagging control of outer ring and inner ring virtual synchronous
Control, both ends VSC converter station status is completely reciprocity, but needs to communicate to guarantee that value and power reference is unified.Although using VSG technology
System inertia can be increased, provide frequency support, but sensitive to the exchange equivalent stiffness coefficient of side system, the equivalent rigidity of AC system
Coefficient will affect output distribution relationship between direct current system and synchronous motor unit, and in actual conditions, system equivalent parameters is difficult to
It obtains, therefore it is controllable to cannot achieve DC transmission system power.
To solve the above problems, the present invention proposes one kind based on direct current frequency limiter (Frequency limit
Controller, FLC) and improvement virtual synchronous generator techniques (virtual synchronous generator, VSG) phase
In conjunction with receiving end MMC improve dynamic frequency support and control strategy.When receiving end power grid generation power disturbance causes frequency to change, application
The receiving end MMC transient power response of the mentioned method of the present invention automated tos respond to component comprising frequency and direct frequency controls component two
Point, power support can not only be carried out quickly to improve system damping and frequency stability, moreover it is possible to realize identical with routine FLC
Stable state transmitting power control function.
Bibliography
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Automation, 2013,37 (15): 3-14.
[2] development and application [J] China electricity of the advanced AC and DC transmission technology of Tang Guangfu, Pang Hui, He Zhiyuan in China
Machine engineering journal, 2016,36 (7): 1760-1771.
[3] Zhang Donghui, Feng Xiaodong, Sun Jingqiang wait flexible DC transmission to be applied to the south research [J] electricity of south electric network
Network technology, 2011,05 (2): 1-6.
[4] Lee visits, and Aniruddha M.Gole, Zhao Chengyong considers the modularization multi-level converter of internal dynamics
Small-signal model [J] Proceedings of the CSEE, 2016,36 (11): 2890-2899.
[5] Yang Xiaofeng, Zheng Qionglin, Xue Yao wait the topology and industrial application summary [J] electricity of modularization multi-level converter
Network technology, 2016,40 (01): 1-10.
[6] Li Wenjin, Tang Guangfu, Kang Yong, wait based on VSC-HVDC double-fed type speed changing and constant frequency Wind turbines starting and simultaneously
Network control system [J] Proceedings of the CSEE, 2014,34 (12): 1864-1873.
[7] An Ting, Bjarne, Andersen wait the Central Europe high-voltage direct current power grid technical forum to summarize [J] electric power network technique,
2017,41 (8): 2407-2416.
[8] Beijing P KUNDUR. power system stability and control [M]: China Electric Power Publishing House, 2001.
[9] quantitative analysis [J] Automation of Electric Systems of Xu Taishan, Xue Yusheng transient frequency deviation acceptability,
2002,26 (19): 7-10.
[10]Chaudhuri N.R.,Majumder R.,Chaudhuri B.System Frequency Support
through Multi-Terminal DC(MTDC)Grids[J].IEEE Transactions on Power Systems,
2013,28(1):347-356.
[11] Zhu Rui can, Li Xingyuan, Ying great Li .VSC-MTDC interacted system frequency stabilization control strategy [J] power grid skill
Art, 2014,38 (10): 2729-2734.
[12] Zhu Rui can, Wang Yuhong, Li Xingyuan, wait for VSC-HVDC interacted system additional frequency control strategy
[J] Automation of Electric Systems, 2014,38 (16): 81-87.
[13]Kirakosyan A.,El-Saadany E.F.,Moursi M.S.E.,et al.DC Voltage
Regulation and Frequency Support in Pilot Voltage Droop Controlled Multi
Terminal HVDC Systems[J].IEEE Transactions on Power Delivery,2017,PP(99):1.
[14] Chen Yiping, Cheng Zhe, Zhang Kun wait HVDC transmission system isolated operation chirping strategies [J] China motor
Engineering journal, 2013,33 (4): 96-102.
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Method [J] Proceedings of the CSEE processed, 2013,33 (16): 137-143.
[16] Wang Huawei, Han Minxiao, Fan Yuanyuan, wait exhale under distant direct current decoupled mode sending frequency characteristic and
Control strategy [J] electric power network technique, 2013,37 (5): 1401-1406.
[17] Zhao Liang, Qin Qin, Guo Qiang wait illiteracy DC transmission engineering sending end isolated island frequency control problem [J] power grid skill in
Art, 2008,32 (21): 22-25.
[18] Gao Qin, Chen Yiping, Zhu Lin wait the control strategy optimization of frequency limiter in the how DC asynchronous interacted system of
Design [J] Automation of Electric Systems, 2018,42 (12): 167-172.
[19] Xu Haizhen, Zhang Xing, Liu Fang wait VSG control strategy [J] China of the based on lead-lag link virtual inertia
Electrical engineering journal, 2017,37 (07): 1918-1927.
[20] Yao Weizheng, Yang Meijuan, Zhang Hailong, wait .VSC-HVDC receiving end inverter participate in power grid frequency modulation VSG control and
Its innovatory algorithm [J] Proceedings of the CSEE, 2017,37 (2): 525-533.
[21]Minyuan G.,Jingzhou C.,Chao W.,et al.The Frequency Regulation
Scheme of Interconnected Grids with VSC-HVDC Links[J].IEEE Transactions on
Power Systems,2017,32(2):864-872.
Summary of the invention
In view of the above-mentioned problems, the present invention provides a kind of controlling party of promotion mains frequency stability for MMC-HVDC
Method.Technical solution is as follows:
A kind of flexible direct current system converter station promotion mains frequency stability control method, this method are limited based on direct current frequency
Device processed
FLC control and virtual synchronous, which control, to be realized, FLC controlling unit is by detection AC network frequency variation and adds
Frequency feedback control loop obtains active power regulation increment Delta P needed for MMC carries out frequency supportFLC.It is characterized in that, logical
It crosses the active power controller loop based on virtual synchronous control and obtains the frequency reference and phase reference of MMC output voltage, pass through
Reactive power or alternating voltage control loop obtain the voltage magnitude reference of MMC output voltage；Obtaining output voltage phase ginseng
It examines with after amplitude reference, the control of alternating voltage Closed loop track is realized by voltage and current Double-loop Control Strategy, wherein
The method of the frequency reference of MMC output voltage is obtained by the active power controller loop controlled based on virtual synchronous
Are as follows: the active power regulation increment Delta P for obtaining FLC controlling unitFLC, active power reference Pset, and practical MMC converter station note
Enter the active-power P of AC networkmmcDifference, and with frequency set point ωpllIt is added, obtains frequency reference ωref:
In formula, HmmcAnd βmmcRespectively MMC virtual inertia and frequency droop characteristic coefficient；Frequency set point ωpllTo use
Real-time locking phase frequency values obtained are carried out to receiving end power grid after low-pass filtering treatment；S is transmission function variable.
The conventional FLC control that flexible direct current participates in frequency control refers to that soft straight MMC converter station is controlled using conventional vector, and
By detection AC network frequency variation and additional frequency feedback control loop, obtains MMC and have needed for frequency support
Function power adjustment increment, and then control MMC and inject AC network active power, reach frequency control purpose.
Using it is proposed by the present invention based on direct current frequency limiter (Frequency limit controller, FLC) and
The receiving end MMC that virtual synchronous generator techniques (virtual synchronous generator, VSG) is combined is improved to improve
Dynamic frequency support and control strategy, when receiving end power grid generation power disturbance causes frequency to change, the response of receiving end MMC transient power
Component and direct frequency control component two parts are automated toed respond to comprising frequency, can not only carry out power support quickly to improve is
System damping and frequency stability, moreover it is possible to realize stable state transmitting power control function identical with routine FLC.
Detailed description of the invention
Flexible direct current interacted system (MMC-HVDC) of the Fig. 1 based on MMC；
Fig. 2 improves frequency control structure schematic diagram；
Fig. 3 FLC Absent measures structural schematic diagram；
Fig. 4 improves control strategy receiving end MMC small-signal model；
Fig. 5 locking phase low-pass filtering link small-signal model；
Fig. 6 simulation result (when frequency is in dead zone range), (a) receiving-end system frequency respond (b) direct current system and transmit function
Rate；
Fig. 7 simulation result (FLC link normal control), (a) receiving-end system frequency respond (b) direct current system transimission power and ring
Answer (c) FLC link direct current transmission power regulation；
Fig. 8 simulation result (FLC Absent measures saturation), (a) receiving-end system frequency respond (b) direct current system transimission power and ring
Answer (c) FLC link direct current transmission power regulation.
Specific embodiment
Of the invention is described in detail with reference to the accompanying drawings and examples.
A kind of novel dynamic frequency support and control combined based on FLC and improvement virtual synchronous control proposed by the present invention
Method, as shown in Figure 2, wherein FLC controlling unit is as shown in Figure 3.Consider equivalent unit rotor characteristic, governor characteristic and vapour
The receiving end AC network frequency dynamic of wheel machine unit characteristic may be expressed as:
In formula, Δ ω, Δ Pm、ΔPLWith Δ PmmcRespectively equivalent unit output frequency, mechanical output, load and receiving end
MMC injecting power, H and D are respectively equivalent unit equivalent inertia and damping；1/R is the primary frequency modulation characteristic of equivalent unit；GM
(s) for simulating equivalent machine unit speed regulating device and the comprehensive dynamic characteristic of turbine, steady-state value 1.
From the above equation, we can see that being carried out after receiving end power grid disturbs by injecting AC network active power to receiving end MMC
Control can make MMC to participate in receiving end mains frequency stability contorting.Under stable state, frequency variation Δ ω are as follows:
β is the equivalent stiffness coefficient of AC network in formula, meets β=D+1/R.
The conventional FLC control that flexible direct current participates in frequency control refers to that soft straight MMC converter station is controlled using conventional vector, and
By detection AC network frequency variation and additional frequency feedback control loop, obtains MMC and have needed for frequency support
Function power adjustment increment, and then control MMC and inject AC network active power, reach frequency control purpose.FLC control is usually adopted
With reversed frequency difference involution model cootrol logic as shown in Figure 3.ω in figure0It is respectively frequency rated value and practical AC system with ω
Frequency；DFmaxAnd DFminIt is the upper and lower limit of system frequency difference, G respectivelyfIt (s) is first-order low-pass wave link；±FbandIt is FLC frequency
Controlling dead error；kpAnd kiIt is the proportionality coefficient and integral coefficient of PI controller respectively；PmodmaxAnd PmodminIt is MMC respectively in frequency
The upper limit value and lower limit value of dc power regulated quantity is exported during support；PsetFor MMC converter station stable state transmitting active power setting value,
ΔPFLCFor FLC link dc power regulated quantity, Pref,mmcFor MMC converter station final output active power reference value, which is sent into
MMC power closed-loop control link.When being controlled using conventional FLC, systematic steady state frequency variation and the active regulated quantity of converter station with
There are corresponding relationships shown in table 1 for load variations amount.
Corresponding relationship between 1 steady frequency variable quantity of table and the active regulated quantity of converter station and load variations amount
As the above analysis: 1) essence of FLC control is when load disturbance occurs for AC system and frequency variation is more than
It in the case of set dead zone, quicklys increase (or reduction) direct current transmission power and participates in system frequency to offset sub-load disturbance
Control；2) since FLC control without utilizing frequency change rate information, therefore also can not be just had according to frequency variation
Effect improves inertia and the damping of equivalent AC system.
Although conventional FLC control strategy can adjust receiving end converter station power output according to system frequency variable quantity and realize frequency
Rate support, but system damping and optimization frequency dynamic characteristic can not be effectively improved.For this purpose, the present invention propose it is a kind of based on FLC and
It improves virtual synchronous and controls the novel dynamic frequency support and control method combined, as shown in Figure 2.This method basic principle is such as
Under: by obtaining the frequency and phase reference of MMC output voltage based on the active power controller loop for improving virtual synchronous control,
The voltage magnitude reference of MMC output voltage is obtained by reactive power or alternating voltage control loop；Obtaining output voltage phase
After position reference and amplitude reference, voltage and current Double-loop Control Strategy can be passed through and realize the control of alternating voltage Closed loop track.
In based on the active power controller loop for improving virtual synchronous control, input as active power reference Pset、FLC
Link dc power regulated quantity Δ PFLCAnd the active-power P of practical MMC converter station injection AC networkmmcDifference, then pass through
Virtual synchronous controlling unit (wherein HmmcAnd βmmcRespectively MMC virtual inertia and frequency droop characteristic coefficient), obtain output frequency
Rate increment.Compared to traditional virtual synchronization control algorithm, frequency set point is abandoned using constant rated frequency value in the present invention,
Selection is used by carrying out real-time locking phase actual frequency values obtained to receiving end power grid, and is obtained by low-pass filtering link
ωpll, finally set as frequency.The purpose so handled is so that the final stable state output of MMC is able to satisfy Pmmc=Pset+Δ
PFLC, i.e., can reach under stable situation and the FLC completely the same power control target of routine.
It is as shown in Figure 4 that receiving end converter station improves frequency control small-signal model.It is available from figure 4, it improves and controls lower MMC progress
Power out-put characteristic when frequency response:
G in formulapllIt (s) is a-c cycle locking phase low-pass filtering link transmission function, it specifically can a-c cycle as shown in Figure 5
Locking phase low-pass filtering link small-signal model is derived by, and is expressed as follows:
In formula, kp_pllAnd ki_pllRespectively phaselocked loop PI controller proportionality coefficient and integral coefficient, Tf,pllFor single order low pass
Filter link time constant.
MMC power response includes two parts in transient process, and the present invention is referred to as direct frequency control component and frequency
Control component is automated toed respond to, wherein direct frequency control component is determined that frequency automated tos respond to control point by conventional FLC control algolithm
Amount is determined by virtual synchronous control algolithm and frequency phase lock ring low-pass filtering link dynamic characteristic.It is obvious that the low-pass filtering time
Constant is smaller, and it is more unobvious that frequency automated tos respond to control effect；As low-pass filtering time constant increases, this component frequency is automatic
The effect of response control will highlight, be conducive to improve frequency stability, increase damping to reduce frequency variation rate, when system into
After entering stable state, this part component automatic clear, so that MMC stable state control effect is finally determined by FLC.
By previous analysis it is found that load disturbance is of different sizes, for using the MMC converter station work for improving control method for frequency
Make state difference, the dynamic characteristic of control system is also different.When load disturbance very little, frequency variation is caused to be located at FLC movement dead
Area's range, the FLC controlling unit for improving frequency control strategy at this time, which participates in frequency control for MMC, not to be influenced；When load is disturbed
Dynamic to increase, when frequency variation being caused to be more than dead zone and do not result in FLC control saturation, the FLC link for improving frequency control is in
Normal control state；When load disturbance is sufficiently large, cause to improve power in the FLC controlling unit of frequency control strategy increase (or
Reduce) reach PI controller upper limit value Pmodmax(or lower limit value Pmodmin), it will be so that FLC controlling unit be saturated.Therefore, next
Dead zone range, FLC link normal control and FLC Absent measures, which are in, for frequency respectively is saturated analysis system under three kinds of operating conditions
Dynamic frequency response characteristic.
1) dynamic frequency Analysis of response
(a) frequency is in dead zone range
When frequency variation is located at the operating dead zone FLC range, FLC controlling unit Δ PFLC=0, it is controlled using conventional FLC
When, system response is as follows:
In conjunction with Δ PFLC=0 and (1) and formula (3) can obtain, it is as follows using system response when improving frequency control:
By formula (6) it is found that using frequency control, steady-state system frequency variation is improved are as follows:
By table 1 and formula (7) it is found that when frequency is in dead zone range, frequency control is controlled and improved using conventional FLC, surely
State system frequency variable quantity is identical.
(b) FLC link normal control
By taking sudden increase in load causes system frequency to decline as an example, power increases in FLC at this time, and PI controller works.By Fig. 3
It is found that FLC link dc power regulated quantity Δ PFLCFor
At this point, using the MMC active power of output Δ P of routine FLC control,mmcFor
ΔPmmc=Gcpi(s)ΔPref,mmc=Gcpi,d(s)Gc,FLC(-Δω-Fband) (9)
G in formulacpi,d(s) it is d shaft current closed loop transfer function, under dq coordinate system, is expressed as follows:
In formula, kpidAnd kiidRespectively indicate the proportionality coefficient and integral coefficient of converter station d shaft current ring PI control.
It brings formula (9) into formula (1), can obtain as follows using system frequency dynamic characteristic when routine FLC control:
It can be obtained in conjunction with (1), (3) and formula (8), as follows using system response when improving frequency control:
It is by formula (12) it is found that as follows using steady-state system frequency characteristic when improving frequency control:
Δ ω=- Fband (13)
By table 1 and formula (13) it is found that when FLC link normal control, frequency control is controlled and improved using conventional FLC, surely
State system frequency variable quantity is identical.
(c) FLC Absent measures are saturated
By taking big sudden load increase causes system frequency to decline as an example, power in FLC is caused to increase up to PI controller upper limit value
Pmodmax, i.e. Δ PFLC=Pmodmax。
At this point, using the MMC active power of output Δ P of routine FLC control,mmcFor
ΔPmmc=Gcpi(s)ΔPref,mmc=Gcpi(s)Pmodmax (14)
It brings formula (14) into formula (1), can obtain as follows using system frequency dynamic characteristic when routine FLC control:
In conjunction with Δ PFLC=Pmodmax, (1) and formula (3) can obtain, it is as follows using system response when improving frequency control:
It is by formula (16) it is found that as follows using system response when improving frequency control:
By table 1 and formula (17) it is found that when FLC link normal control, frequency control is controlled and improved using conventional FLC, surely
State system frequency variable quantity is identical.
For the validity of the mentioned control strategy of the verifying present invention, built in simulation software PSCAD/EMTDC as shown in Figure 1
Based on MMC flexible direct-current interacted system.System parameter is as shown in table 2.In simulations, sending end converter station uses constant DC voltage
Control, receiving end converter station are respectively adopted conventional FLC control and improve frequency control strategy.
2 flexible direct current system parameter of table
When being in dead zone range for verifying frequency, the validity of the mentioned control strategy of the present invention, the 50s moment puts into 50MW
Load.Receiving end AC system frequency and direct current system transimission power when being controlled using conventional FLC and improving frequency control strategy
Respectively as shown in Fig. 6 (a) and (b).As seen from the figure, it controlling compared to FLC, when using improving frequency control strategy, can quickly transfer
Direct current system transimission power provides Damper Braces for system, and system frequency fluctuation peak value is reduced by about 0.015Hz, steady-state system frequency
Rate deviation is about -0.021Hz；Direct current system stable state transimission power is 800MW.The above results with theory analysis one above
It causes.
When to verify FLC link normal control, the validity of the mentioned control strategy of the present invention, the 50s moment puts into 400MW
Load.Receiving end AC system frequency when being controlled using conventional FLC and improving frequency control strategy, direct current system transimission power and
FLC link dc power regulated quantity is respectively as shown in Fig. 7 (a)-(c).As seen from the figure, when be in FLC link normal control operating condition,
When using FLC and improving frequency control strategy, FLC controlling unit steady-state DC power adjustment is each about 180MW, direct current system
Stable state transimission power is each about 980MW, and systematic steady state frequency departure is -0.1Hz (i.e. dead zone frequency).And phase is controlled with FLC
Than using improvement control strategy to provide Damper Braces for system, frequency fluctuation peak value is reduced by about 0.06Hz.The above results are with before
Literary theory analysis is consistent.
When being saturated for verifying FLC Absent measures, the validity of the mentioned control strategy of the present invention, the 50s moment is put into
1000MW (1pu) load.Receiving end AC system frequency, direct current system when being controlled using conventional FLC and improving frequency control strategy
Such as Fig. 8 (a)-(c) is shown respectively for transimission power and FLC link dc power regulated quantity.As seen from the figure, when in FLC link
Control saturation operating condition, when using FLC and improving frequency control strategy, FLC controlling unit steady-state DC power adjustment is straight
Streaming system power adjustment upper limit 400MW, direct current system stable state transimission power are 1200MW, and systematic steady state frequency departure is absolute
Value is greater than dead zone (0.1Hz).And compared with FLC control, improvement control strategy is used to provide Damper Braces, frequency fluctuation for system
Peak value is reduced by about 0.2Hz.The above results are consistent with theory analysis above.
Claims (1)
1. a kind of flexible direct current system converter station promotes mains frequency stability control method, this method is limited based on direct current frequency
Device FLC control and virtual synchronous control realize that FLC controlling unit is anti-by detection AC network frequency variation and additional frequency
Control loop is presented, active power regulation increment Delta P needed for MMC carries out frequency support is obtainedFLC.It is characterized in that, by being based on
The active power controller loop of virtual synchronous control obtains the frequency reference and phase reference of MMC output voltage, passes through idle function
Rate or alternating voltage control loop obtain the voltage magnitude reference of MMC output voltage；Obtaining output voltage phase reference and width
After value reference, the control of alternating voltage Closed loop track is realized by voltage and current Double-loop Control Strategy, wherein
The method of the frequency reference of MMC output voltage is obtained by the active power controller loop controlled based on virtual synchronous are as follows:
The active power regulation increment Delta P that FLC controlling unit is obtainedFLC, active power reference Pset, and the injection of practical MMC converter station
The active-power P of AC networkmmcDifference, and with frequency set point ωpllIt is added, obtains frequency reference ωref:
In formula, HmmcAnd βmmcRespectively MMC virtual inertia and frequency droop characteristic coefficient；Frequency set point ωpllFor using process
Real-time locking phase frequency values obtained are carried out to receiving end power grid after low-pass filtering treatment；S is transmission function variable.
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| CN110535147A (en) * | 2019-07-31 | 2019-12-03 | 华北电力大学（保定） | A kind of alternating current-direct current mixing microgrid H∞Control method for frequency |
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| CN110336305A (en) * | 2019-07-22 | 2019-10-15 | 华北电力大学（保定） | A kind of suitable double-fed fan motor unit participates in the improvement additional frequency control method of system frequency adjusting under short trouble |
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| CN110535147B (en) * | 2019-07-31 | 2023-10-10 | 华北电力大学（保定） | AC/DC hybrid micro-grid H ∞ Frequency control method |
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| CN112564130A (en) * | 2020-11-30 | 2021-03-26 | 东北电力大学 | Method for improving stability performance of receiving end system of wind power through flexible direct current grid connection |
| CN114666200A (en) * | 2022-02-14 | 2022-06-24 | 国电南瑞科技股份有限公司 | Loop detection method and device for intelligent substation network and storage medium |
| US11641109B2 (en) | 2022-05-17 | 2023-05-02 | Zhejiang University | Grid-forming wind turbine control method for diode rectifier unit-based offshore wind power transmission system |
| CN114640141B (en) * | 2022-05-17 | 2022-08-05 | 浙江大学 | Network-building type fan control method for offshore wind power diode rectification unit sending-out system |
| CN114640141A (en) * | 2022-05-17 | 2022-06-17 | 浙江大学 | Network-building type fan control method for offshore wind power diode rectification unit sending-out system |
| CN115733141A (en) * | 2022-11-18 | 2023-03-03 | 国网江苏省电力有限公司电力科学研究院 | Frequency additional control method and device of inter-line moisture controller |
| CN115733141B (en) * | 2022-11-18 | 2024-01-23 | 国网江苏省电力有限公司电力科学研究院 | Frequency additional control method and device for inter-line power flow controller |
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