CN104022522B - A kind of coordination control method of multiterminal flexible direct current power transmission system - Google Patents
A kind of coordination control method of multiterminal flexible direct current power transmission system Download PDFInfo
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- CN104022522B CN104022522B CN201410253118.5A CN201410253118A CN104022522B CN 104022522 B CN104022522 B CN 104022522B CN 201410253118 A CN201410253118 A CN 201410253118A CN 104022522 B CN104022522 B CN 104022522B
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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
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses a kind of coordination control method of multiterminal flexible direct current power transmission system, DC transmission system comprises leading current conversion station, wind energy turbine set current conversion station, assist exchanging circuit station and active power controller current conversion station; Leading current conversion station is used for the control of whole system direct voltage; Wind energy turbine set current conversion station is responsible for the active power collecting wind farm group; Assist exchanging circuit station is used for the auxiliary control realizing system dc voltage; Active power controller current conversion station is used for the constant active power of its AC electrical grid transmission; Described assist exchanging circuit station and active power controller current conversion station all introduce the control based on improving direct voltage-active power decline regulating characteristics.Beneficial effect of the present invention: distribute for the DC voltage control under any operating condition between each current conversion station of Multi-end flexible direct current transmission system and active power, ensures Multi-end flexible direct current transmission system seamlessly transitting between each running status.
Description
Technical field
The present invention relates to electric field, particularly relating to a kind of coordination control method of multiterminal flexible direct current power transmission system based on improving decline regulating characteristics.
Background technology
Under energy scarcity and the increasingly serious situation of environmental pollution, the input of countries in the world in the renewable energy power generation such as wind energy, solar energy constantly expands, and wherein the exploitation of extensive offshore wind farms has become the main trend of Wind Power Utilization in the world.Because marine wind electric field is away from seashore, the bank land electrical network that it connects is also much weaker, wind-electricity integration all has considerable influence to the stability of connected electrical network and the quality of power supply etc., when developing offshore wind farm on a large scale, Multi-end flexible direct current transmission becomes optimal selection, and therefore its correlative study receives and pays close attention to widely.DC voltage control strategy is the importance of Multi-end flexible direct current transmission technology, and it directly determines stability and the reliability of plant running.
For the DC voltage control and active power that ensure transmission system under normal operation, abnormal running and fault condition distribute, need the coordination control strategy developing a kind of Multi-end flexible direct current transmission system in a hurry.The patent No. is the Chinese patent of 201310585802: " a kind of control system of Multi-end flexible direct current transmission system and control method thereof "; disclose a kind of control system and control method thereof of Multi-end flexible direct current transmission system, this patent realizes control method by calculating multiterminal element network trend and carrying out analyzing and formulate control & protection strategy.The patent No. is the Chinese patent of 201210442336: " a kind of coordination control method of multiterminal flexible direct current power transmission system ", disclose a kind of coordination control method of multiterminal flexible direct current power transmission system, this patent to give between station communication effectively and between station in communication failures situation leading station switch to the control method for coordinating of DC voltage control because of slave station when fault is stopped transport.The defect that above patent and prior art exist is:
1.201310585802 Chinese patents only give a kind of optimal load flow according to DC network and carry out analyzing and formulate control & protection strategy thus the method for realization control; the DC voltage control of Multi-end flexible direct current transmission system under all operating conditions cannot be ensured, especially cannot ensure the system safety under the extreme operating conditions such as current conversion station stoppage in transit.
2.201210442336 Chinese patents to only give between a kind of station communication effectively and between station in communication failures situation leading station switch to the control method for coordinating of DC voltage control because of slave station when fault is stopped transport.The method realizes the DC voltage control under fault condition by the control mode switch of standby station, its defect is that the system concussion in control mode switch process is comparatively large, cannot realize seamlessly transitting of system running state; Meanwhile, the method does not provide detailed calculating and the system of selection of system parameters.
Summary of the invention
Object of the present invention is exactly to solve the problem, provide a kind of coordination control method of multiterminal flexible direct current power transmission system based on improving decline regulating characteristics, the method designs the advanced control strategy of current conversion station based on local controller, ensure normal to run, the DC voltage control of Multi-end flexible direct current transmission system and active power balance under abnormal running and fault condition, and realize seamlessly transitting of system running state.
To achieve these goals, the present invention adopts following technical scheme:
A kind of coordination control method of multiterminal flexible direct current power transmission system, described DC transmission system at least comprises leading current conversion station, assist exchanging circuit station and active power controller current conversion station; Described leading current conversion station is used for the control of whole system direct voltage; Assist exchanging circuit station is used for the auxiliary control realizing system dc voltage; Active power controller current conversion station is used for the constant active power of its AC electrical grid transmission;
Under nominal situation, described assist exchanging circuit station and leading current conversion station cooperation realize the DC voltage control of Multi-end flexible direct current transmission system jointly; Active power controller current conversion station adopts to be determined active power controller and determines Reactive Power Control;
When leading current conversion station enters current-limit mode or stops transport, assist exchanging circuit station adopts based on improving the DC voltage control of direct voltage-active power decline regulating characteristics and determining Reactive Power Control;
When leading current conversion station and assist exchanging circuit station cannot maintain DC transmission system power-balance, active power controller current conversion station introduces for subsequent use control of control as DC voltage control based on improving direct voltage-active power decline regulating characteristics.
Described assist exchanging circuit station is specially based on the DC voltage control mode improving direct voltage-active power decline regulating characteristics:
When assist exchanging circuit station alternating current-direct current exchanges power P in [-δ, δ] scope during fluctuation, introducing dead zone function; By regulating the direct voltage dead band value U at assist exchanging circuit station
dzsize, the cooperation control with leading current conversion station can be realized, realize DC network optimal load flow control; Wherein, δ gets 0 ~ 0.02p.u.;
If the direct voltage reference value at assist exchanging circuit station is U
dcref,
DC voltage value when assist exchanging circuit station is greater than (U
dcref-U
dz) and be less than (U
dcref+ U
dz) time, assist exchanging circuit station is 0 to the direct current power of DC side feed-in; Now, the operational mode at assist exchanging circuit station is STATCOM pattern;
Direct voltage when assist exchanging circuit station is less than (U
dcref-U
dz) or be greater than (U
dcref+ U
dz) time, the slope that assist exchanging circuit station enters based on direct voltage-active power is k
assdecline control model, realize direct voltage have difference control;
When direct voltage is greater than maximum direct voltage limit value U when assist exchanging circuit station is normally run
dcmor the minimum direct current voltage limits U be less than when assist exchanging circuit station is normally run
dcntime, assist exchanging circuit station enters current-limit mode, runs on non-normal operation mode.
The described direct voltage reference value U choosing assist exchanging circuit station
dcrefwith the direct voltage dead band value U at assist exchanging circuit station
dzaccording to be:
(1) direct voltage reference value U
dcrefleading current conversion station direct voltage command value should be got;
(2) dead zone voltage U
dzshould guarantee to avoid the zero crossing in active power to produce vibration.
Described assist exchanging circuit station enters the slope value k of the decline control model based on direct voltage
asschoosing method be:
(1) ensure that the DC voltage value of each current conversion station of DC transmission system under each operating mode is not out-of-limit, and leave certain margin of safety;
(2) under guarantee stable situation, the active power fluctuation scope at assist exchanging circuit station is 0.5% ~ 5%, i.e. slope value k
assbe less than k
%P, k
%Poutput for assist exchanging circuit station be specified active power and active power value fluctuates in 0.5% ~ 5% scope time control characteristic slope of a curve value;
(3) under the enough operating mode of total change of current capacity at minimax operational mode, leading current conversion station and assist exchanging circuit station, slope value k
asschoose and should ensure that leading current conversion station does not enter current-limit mode;
(4) slope value k
assbe less than min{k
eqM, k
eqN, k
eqM, k
eqNbe respectively maximum, assist exchanging circuit station control characteristic slope of a curve value when leading current conversion station enters current-limit mode prior to assist exchanging circuit station just under minimum operational mode.
Described active power controller current conversion station is specially based on the DC voltage control improving direct voltage-active power decline regulating characteristics:
During normal operation, active power controller current conversion station transmits constant active power value, and its operating voltage range is [U
dcm, U
dcn];
When the leading current conversion station of direct current system and assist exchanging circuit station cannot maintain system power balance, the direct voltage of all current conversion stations exceeds normal operation range;
Maximum direct voltage limit value U under active power controller current conversion station direct voltage is greater than active power controller current conversion station nominal situation
dcmor be less than minimum direct current voltage limits U under active power controller current conversion station nominal situation
dcntime, the slope that active power controller current conversion station enters based on direct voltage-active power is k
apcdecline control model, get involved the DC voltage control of direct current system;
The maximum direct voltage limit value U of slope characteristics section under direct voltage is greater than decline control model
dcMor be less than the minimum direct current voltage limits U of slope characteristics section under decline control model
dcNtime, active power controller current conversion station enters current-limit mode, restriction active power and active current value.
Maximum, the minimum direct current voltage U of described active power controller current conversion station nominal situation
dcm, U
dcnchoose and depend on the DC voltage value of active power controller current conversion station under maximum, minimum operational mode, and leave certain nargin.
The slope k that described active power controller current conversion station decline controls
apcchoosing method be:
(1) under guarantee damage, the direct voltage of each current conversion station of DC transmission system is not out-of-limit, and leaves certain margin of safety;
(2) under guarantee stable situation, the active power fluctuation scope at assist exchanging circuit station is 0.5% ~ 5%, i.e. slope value k
assbe less than k
%P, k
%Poutput for assist exchanging circuit station be specified active power and active power value fluctuates in 0.5% ~ 5% scope time control characteristic slope of a curve value.
The present invention completes a kind of Multi-end flexible direct current transmission system coordination control strategy based on improving decline regulating characteristics, the improvement decline control strategy at assist exchanging circuit station and the improvement control strategy of active power controller current conversion station is given based on improvement direct voltage-active power decline regulating characteristics, analyze the mode of operation of two current conversion stations, give the foundation of assist exchanging circuit station and active power controller current conversion station Selecting parameter according to the distribution of the trend of DC network and minimax operational mode.
Beneficial effect of the present invention:
1. the present invention is for the design of the coordination control strategy of Multi-end flexible direct current transmission system in the grid-connected situation of large-scale wind power, the perfect hierarchy of control of Multi-end flexible direct current transmission system, realizes it based on the control strategy improving decline regulating characteristics for assist exchanging circuit station and active power controller current conversion station.
2. the present invention distributes for the DC voltage control between each current conversion station of Multi-end flexible direct current transmission system under any operating condition and active power, ensures Multi-end flexible direct current transmission system seamlessly transitting between each running status.
3. the present invention gives the improvement decline control strategy at assist exchanging circuit station and the improvement control strategy of active power controller current conversion station for based on improvement direct voltage-active power decline regulating characteristics, analyze the mode of operation of two current conversion stations, give the foundation of assist exchanging circuit station and active power controller current conversion station Selecting parameter according to the distribution of the trend of DC network and minimax operational mode.
Accompanying drawing explanation
Fig. 1 is the improvement direct voltage-active power decline regulating characteristics at assist exchanging circuit station;
Fig. 2 (a) is the improvement direct voltage under active power controller current conversion station bidirectional power operational mode-active power decline regulating characteristics;
Fig. 2 (b) is the improvement direct voltage under active power controller current conversion station unidirectional power operational mode-active power decline regulating characteristics;
Fig. 3 is the safe range reference diagram of the slope characteristics slope over 10 at assist exchanging circuit station;
Fig. 4 (a) is the safe range reference diagram of slope characteristics slope over 10 under active power controller current conversion station bidirectional power operational mode;
Fig. 4 (b) is the safe range reference diagram of slope characteristics slope over 10 under active power controller current conversion station unidirectional power operational mode;
Fig. 5 is the control system schematic diagram at assist exchanging circuit station;
Fig. 6 is the control system schematic diagram of APC current conversion station.
Embodiment
Below in conjunction with accompanying drawing and embodiment, the invention will be further described.
Based on the coordination control method of multiterminal flexible direct current power transmission system improving decline regulating characteristics, comprise the control strategy of each current conversion stations such as leading current conversion station, wind energy turbine set current conversion station, assist exchanging circuit station and active power controller (APC) current conversion station;
Each current conversion station adopts the advanced control strategy based on local controller; Leading current conversion station is responsible for the control of direct voltage, adopts constant DC voltage control and determines Reactive Power Control strategy; Wind energy turbine set current conversion station is responsible for the active power collecting wind farm group, adopts FREQUENCY CONTROL and alternating voltage to control; Assist exchanging circuit station is auxiliary realizes DC voltage control, adopts the DC voltage control of band falling characteristic and determines Reactive Power Control strategy; Active power controller current conversion station is used for the constant active power of its AC electrical grid transmission, adopt and determine active power controller and determine Reactive Power Control strategy, and introduce for subsequent use control of control strategy as DC voltage control based on improving direct voltage-active power decline regulating characteristics;
The converter of each current conversion station adopts inner ring current decoupled control device; Inner ring Current Control adopts current feedback and voltage feed-forward control, to improve the tracking individual features of current controller; Current inner loop controller adopts pi regulator to eliminate the steady-state error of current tracking; Each current conversion station adopts vector control and pulse modulation (PWM) technology, controls with the quick independence realizing meritorious and reactive power.
First as follows to each parameter declaration:
U
dcnminimum direct current voltage limits during long-play normal for assist exchanging circuit station, U
dcmfor maximum direct voltage limit value during the normal long-play in assist exchanging circuit station, 2U
dzfor the dead zone voltage at assist exchanging circuit station, U
dcreffor the direct voltage reference value at assist exchanging circuit station, P
mAXfor the maximum active power limit value at assist exchanging circuit station, P
mINfor the minimum active power limit value at assist exchanging circuit station, k
assfor the slope that the decline of assist exchanging circuit station controls, U
dcNfor the minimum direct current voltage limits of bidirectional power operational mode under active power controller current conversion station damage, U
dcMfor the maximum direct voltage limit value of bidirectional power operational mode under active power controller current conversion station damage, U
dcn1for the minimum direct current voltage limits of bidirectional power operational mode under active power controller current conversion station normal operation, U
dcm1for the maximum direct voltage limit value of bidirectional power operational mode under active power controller current conversion station normal operation, P
reffor active power controller current conversion station flows into the AC active power reference value of DC network, P
mIN1for the minimum active power limit under active power controller current conversion station bidirectional power operational mode, P
mAX1for the maximum active power limit under active power controller current conversion station bidirectional power operational mode, k
apcfor the slope that the decline of active power controller current conversion station bidirectional power operational mode controls, U
dcN1for the minimum direct current voltage limits of unidirectional power mode of operation under active power controller current conversion station damage, U
dcM1for the maximum direct voltage limit value of unidirectional power mode of operation under active power controller current conversion station damage, U
dcn2for the minimum direct current voltage limits of unidirectional power mode of operation under active power controller current conversion station normal operation, U
dcm2for the maximum direct voltage limit value of unidirectional power mode of operation under active power controller current conversion station normal operation, P
mAX2for the maximum active power limit under active power controller current conversion station unidirectional power operational mode, P
mIN2for the minimum active power limit under active power controller current conversion station unidirectional power operational mode, k
apc1for the slope that the decline of active power controller current conversion station unidirectional power operational mode controls.
As shown in Figure 1, for preventing the active power at assist exchanging circuit station out-of-limit, the threshold limit value U of active power in the characteristic curve at this assist exchanging circuit station, is introduced
dcmwith minimum limit value U
dcn.This group limit value U
dcmand U
dcnflow restricter acting in conjunction with vector control strategy, prevents converter from causing damage because running on overload to equipment.
When assist exchanging circuit station alternating current-direct current exchanges power P in [-δ, δ] (δ gets 0 ~ 0.02p.u.) scope during fluctuation, for preventing active power value P from vibrating, simultaneously more reasonable for making DC power flow distribute, dead zone function introduced by controller.By regulating direct voltage dead band value U
dzsize, the cooperation control with leading current conversion station can be realized, realize DC network optimal load flow control.
There are three kinds of control models at assist exchanging circuit station: (1) STATCOM pattern: when direct voltage is greater than (U
dcref-U
dz) and be less than (U
dcref+ U
dz) time, assist exchanging circuit station is 0 to the direct current power of DC side feed-in, and now, operational mode and the STATCOM at assist exchanging circuit station are similar, are mainly AC electrical network and provide dynamic reactive voltage support; (2) decline control model (normal operation mode): when direct voltage is less than (U
dcref-U
dz) or be greater than (U
dcref+ U
dz) time, the slope that current conversion station enters based on direct voltage is k
assdecline control model, realize direct voltage have difference control.Above two kinds of operational modes are the normal operation mode of auxiliary station; (3) current-limit mode: when direct voltage is greater than U
dcmor be less than U
dcntime, auxiliary station enters current-limit mode, runs on non-normal operation mode.Based on vector control and pulse modulation technique, the control system schematic diagram of sub-control station as shown in Figure 5.Current conversion station DC voltage through first-order low-pass ripple link, via U
dc-P characteristic curve obtains active power reference value P
ref.
The reference voltage U at assist exchanging circuit station
dcrefwith the U of dead zone voltage
dzdetermine the startup of falling controller, namely the startup DC voltage value of assist exchanging circuit station slope characteristics section is U
dcref+ U
dz, its basis for selecting is:
(1) direct voltage reference value U
dcrefleading stream voltage instruction value of standing erectly should be got;
(2) dead zone voltage U
dzthe vibration of avoiding producing at active power zero crossing should be guaranteed.
Determine U
dcref, U
dzafterwards, assist exchanging circuit station slope characteristics slope over 10 k
asswith converter active power limit value P
mAX, P
mINdetermine U
dcm, U
dcnsize, thus the power stage size determined under decline control model and DC voltage range.
Slope k
asssystem of selection as follows:
(1) select according to the guarantee each current conversion station of DC transmission system DC voltage value under each operating mode is not out-of-limit, and leave certain margin of safety, in Fig. 3, shadow region is the k that can ensure direct voltage safety
assscope;
(2) under guarantee stable situation, the active power fluctuation scope at assist exchanging circuit station is 0.5% ~ 5%, i.e. slope value k
assbe less than k
%P, k
%Poutput for assist exchanging circuit station be specified active power and active power value fluctuates in 0.5% ~ 5% scope time control characteristic slope of a curve value;
(3) under the enough operating mode of total change of current capacity of minimax operational mode, leading station and auxiliary station, this Selecting parameter should ensure that leading station does not enter current-limit mode; Characteristic curve value k
assbe less than min{k
eqM, k
eqN, k
eqM, k
eqNbe respectively maximum, assist exchanging circuit station control slope value when leading station enters current-limit mode prior to assist exchanging circuit station just under minimum operational mode.
As shown in Figure 2; when grid side voltage fall for a long time, the large disturbances such as change of current fault of stop occur time; the active power transfer at leading current conversion station or assist exchanging circuit station is restricted; cause direct current system cannot continue to maintain its active power balance; thus direct voltage is out of hand, final current conversion station because of protection act out of service.Active power controller current conversion station is designed to the standby station of DC voltage control, introduces slop control as the control strategy under damage.
Improvement direct voltage-active power decline the regulating characteristics of active power controller current conversion station as shown in Figure 2, comprises the operational mode allowing bidirectional power transmission and the operational mode two kinds allowing unidirectional power transfer.Bidirectional power pattern allows current conversion station under abnormal operation condition, to pass through reverse transfer active power to suppress the further rising of DC voltage, it is for maintaining the use capacity of direct voltage apparently higher than unidirectional power operational mode, but simultaneously, the peak modulation capacity of active power vacancy in power switching process to APC current conversion station AC system proposes certain requirement, therefore this kind of control model is applicable to the APC current conversion station that is connected with the medium-and-large-sized electric power system with enough stand-by heat capacity.One-way transmission power mode does not allow effective power flow to overturn, and is applicable to the APC current conversion station be connected with small electrical system.
For bidirectional power operational mode:
Active power controller current conversion station has three kinds of control models:
(1) determine active power controller (normal operation mode): when normally running, active power controller current conversion station transmits constant active power value, and its operating voltage range is [U
dcm1, U
dcn1];
(2) decline control model: when the leading station of direct current system and auxiliary station cannot maintain system power balance, each current conversion station direct voltage exceeds normal operation range; When active power controller current conversion station direct voltage is greater than U
dcm1or be less than U
dcn1time, the slope that active power controller current conversion station enters based on direct voltage-active power is k
apcdecline control model, get involved the DC voltage control of direct current system;
(3) current-limit mode: when direct voltage is greater than U
dcMor be less than U
dcNtime, active power controller current conversion station enters current-limit mode, restriction active power and active current value.Based on vector control and pulse modulation technique, the control system schematic diagram of APC current conversion station as shown in Figure 6.Current conversion station DC voltage through first-order low-pass ripple link, via U
dc-P characteristic curve obtains the correction value P of active power reference value
delta, by P
deltawith original active power reference value P
refand as revised active power reference value.
The minimax direct voltage U of active power controller current conversion station nominal situation
dcm1, U
dcn1determine the startup of falling controller, choosing of this class value depends primarily on the DC voltage value of active power controller current conversion station under minimax operational mode, and should leave certain nargin.
As parameter U
dcm1, U
dcn1after determining, the slope k that the decline of active power controller current conversion station controls
apcwith active power limit P
mAX1, P
mIN1jointly determine U
dcM, U
dcNsize, thus determine active power under decline control model and export and direct voltage range of operation.Slope k
apcsystem of selection as follows:
(1) under guarantee damage, the direct voltage of each current conversion station of DC transmission system is not out-of-limit selects, and leaves certain margin of safety, as shadow region in Fig. 4 is the k that can ensure direct voltage safety
apcscope;
(2) under guarantee stable situation, the active power fluctuation scope at assist exchanging circuit station is 0.5% ~ 5%, i.e. slope value k
assbe less than k
%P, k
%Poutput for assist exchanging circuit station be specified active power and active power value fluctuates in 0.5% ~ 5% scope time control characteristic slope of a curve value.
By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.
Claims (6)
1. a coordination control method of multiterminal flexible direct current power transmission system, described DC transmission system at least comprises leading current conversion station, assist exchanging circuit station and active power controller current conversion station; Described leading current conversion station is used for the control of whole system direct voltage; Assist exchanging circuit station is used for the auxiliary control realizing system dc voltage; Active power controller current conversion station is used for the constant active power of its AC electrical grid transmission; It is characterized in that,
Under nominal situation, described assist exchanging circuit station and leading current conversion station cooperation realize the DC voltage control of Multi-end flexible direct current transmission system jointly; Active power controller current conversion station adopts to be determined active power controller and determines Reactive Power Control;
When leading current conversion station enters current-limit mode or stops transport, assist exchanging circuit station adopts based on improving the DC voltage control of direct voltage-active power decline regulating characteristics and determining Reactive Power Control;
When leading current conversion station and assist exchanging circuit station cannot maintain DC transmission system power-balance, active power controller current conversion station introduces for subsequent use control of control as DC voltage control based on improving direct voltage-active power decline regulating characteristics;
Assist exchanging circuit station is specially based on the DC voltage control mode improving direct voltage-active power decline regulating characteristics:
When assist exchanging circuit station alternating current-direct current exchanges power P in [-δ, δ] scope during fluctuation, introducing dead zone function; By regulating the direct voltage dead band value U at assist exchanging circuit station
dzsize, the cooperation control with leading current conversion station can be realized, realize DC network optimal load flow control; Wherein, δ gets 0 ~ 0.02p.u.;
If the direct voltage reference value at assist exchanging circuit station is U
dcref,
DC voltage value when assist exchanging circuit station is greater than U
dcref-U
dzand be less than U
dcref+ U
dztime, assist exchanging circuit station is 0 to the direct current power of DC side feed-in; Now, the operational mode at assist exchanging circuit station is STATCOM pattern;
Direct voltage when assist exchanging circuit station is less than U
dcref-U
dzor be greater than U
dcref+ U
dztime, the slope that assist exchanging circuit station enters based on direct voltage-active power is k
assdecline control model, realize direct voltage have difference control;
When direct voltage is greater than maximum direct voltage limit value U when assist exchanging circuit station is normally run
dcmor the minimum direct current voltage limits U be less than when assist exchanging circuit station is normally run
dcntime, assist exchanging circuit station enters current-limit mode, runs on non-normal operation mode.
2. a kind of coordination control method of multiterminal flexible direct current power transmission system as claimed in claim 1, is characterized in that, chooses the direct voltage reference value U at assist exchanging circuit station
dcrefwith the direct voltage dead band value U at assist exchanging circuit station
dzaccording to be:
(1) direct voltage reference value U
dcrefleading current conversion station direct voltage command value should be got;
(2) direct voltage dead band value U
dzshould guarantee to avoid the zero crossing in active power to produce vibration.
3. a kind of coordination control method of multiterminal flexible direct current power transmission system as claimed in claim 1, is characterized in that, the slope that described assist exchanging circuit station enters based on direct voltage-active power is k
assthe choosing method of decline control model be:
(1) ensure that the DC voltage value of each current conversion station of DC transmission system under each operating mode is not out-of-limit, and leave certain margin of safety;
(2) under guarantee stable situation, the active power fluctuation scope at assist exchanging circuit station is 0.5% ~ 5%, i.e. slope value k
assbe less than k
%P, k
%Poutput for assist exchanging circuit station be specified active power and active power value fluctuates in 0.5% ~ 5% scope time control characteristic slope of a curve value;
(3) under the enough operating mode of total change of current capacity at maximum, minimum operational mode, leading current conversion station and assist exchanging circuit station, slope value k
asschoose and should ensure that leading current conversion station does not enter current-limit mode;
(4) slope value k
assbe less than min{k
eqM, k
eqN, k
eqM, k
eqNbe respectively maximum, assist exchanging circuit station control characteristic slope of a curve value when leading current conversion station enters current-limit mode prior to assist exchanging circuit station just under minimum operational mode.
4. a kind of coordination control method of multiterminal flexible direct current power transmission system as claimed in claim 1, is characterized in that, described active power controller current conversion station is specially based on the DC voltage control improving direct voltage-active power decline regulating characteristics:
During normal operation, active power controller current conversion station transmits constant active power value, and its operating voltage range is [U
dcn, U
dcm];
When the leading current conversion station of direct current system and assist exchanging circuit station cannot maintain system power balance, the direct voltage of all current conversion stations exceeds normal operation range;
Maximum direct voltage limit value U under active power controller current conversion station direct voltage is greater than active power controller current conversion station nominal situation
dcmor be less than minimum direct current voltage limits U under active power controller current conversion station nominal situation
dcntime, the slope that active power controller current conversion station enters based on direct voltage-active power is k
apcdecline control model, get involved the DC voltage control of direct current system;
The maximum direct voltage limit value U of slope characteristics section under direct voltage is greater than decline control model
dcmor be less than the minimum direct current voltage limits U of slope characteristics section under decline control model
dcntime, active power controller current conversion station enters current-limit mode, restriction active power and active current value.
5. a kind of coordination control method of multiterminal flexible direct current power transmission system as claimed in claim 4, is characterized in that, maximum, the minimum direct current voltage limits U of described active power controller current conversion station nominal situation
dcm, U
dcnchoose and depend on the DC voltage value of active power controller current conversion station under maximum, minimum operational mode, and leave certain nargin.
6. a kind of coordination control method of multiterminal flexible direct current power transmission system as claimed in claim 4, is characterized in that, the slope k that described active power controller current conversion station decline controls
apcchoosing method be:
(1) under guarantee damage, the direct voltage of each current conversion station of DC transmission system is not out-of-limit, and leaves certain margin of safety;
(2) under guarantee stable situation, the active power fluctuation scope at assist exchanging circuit station is 0.5% ~ 5%, i.e. slope value k
assbe less than k
%P, k
%Poutput for assist exchanging circuit station be specified active power and active power value fluctuates in 0.5% ~ 5% scope time control characteristic slope of a curve value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410253118.5A CN104022522B (en) | 2014-06-09 | 2014-06-09 | A kind of coordination control method of multiterminal flexible direct current power transmission system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410253118.5A CN104022522B (en) | 2014-06-09 | 2014-06-09 | A kind of coordination control method of multiterminal flexible direct current power transmission system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104022522A CN104022522A (en) | 2014-09-03 |
| CN104022522B true CN104022522B (en) | 2016-01-13 |
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