CN110165695A - A kind of method and system for hierarchical control multi-terminal direct current transmission system - Google Patents
A kind of method and system for hierarchical control multi-terminal direct current transmission system Download PDFInfo
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- CN110165695A CN110165695A CN201910411958.2A CN201910411958A CN110165695A CN 110165695 A CN110165695 A CN 110165695A CN 201910411958 A CN201910411958 A CN 201910411958A CN 110165695 A CN110165695 A CN 110165695A
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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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- 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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The invention discloses a kind of method and system for hierarchical control multi-terminal direct current transmission system, belong to multi-terminal HVDC transmission control technology field.The method of the present invention includes: a kind of method for hierarchical control multi-terminal direct current transmission system, the method, comprising: tier I acquires multi-terminal direct current transmission system alterating and direct current network data；Tier ii obtains the real work point and reference work point of the sagging control of multi-terminal direct current transmission system；Layer III obtains the sagging control parameter of optimization aim converter station according to the reference work of optimization aim point；Section IV layer obtains converter station signalWith the voltage signal V of converter station DC side real-time measurementi‑com, according to optimization aim real work point (Pi,Vi) and optimization aim reference work pointAnd control parameter, execute the sagging control of MTDC transmission system.Lifting system is received the ability of intermittent new energy power station transient output, the ability of lifting system reply DC system fault and reasonably optimizing DC line and is lost by invention.
Description
Technical field
The present invention relates to multi-terminal HVDC transmission control technology fields, and are used for hierarchical control more particularly, to one kind
The method and system of multi-terminal direct current transmission system.
Background technique
DC power transmission control system layered structure (hierarchy structure of DC transmission
Control system) whole control functions of direct-current transmission converter station and DC power transmission line are divided into several layers time by grade
And the Control system architecture formed.
Each level separates in structure, and the high control function of the high control function level of hierarchy of level of hierarchy can act on
Inferior grade level belonging to it, and action direction be it is unidirectional, i.e., inferior grade level cannot act on high-grade level；Level etc.
The identical each control function of grade and its corresponding hardware and software are separated as far as possible in structure, are influenced each other with reducing；Be directly facing by
The control function of control equipment is arranged in lowest hierarchical level, control system related execution link and also belongs to this level etc.
Grade, their general settings nearby are near controlled device；The major control function of system is distributed to lower level as much as possible
Grade, to improve system availability；When high-rise secondary control breaks down, each lower layer's secondary control can according to the instruction before failure after
Continuous work, and retain control function as much as possible.Complicated control system uses layered structure, and the reliable of operation can be improved
Property, keep influence caused by any controlling unit failure and the extent of injury minimum, while operation operation and maintenance also can be improved
Convenience and flexibility.
DC voltage control is the research emphasis of multi-terminal direct current transmission system control method.In point-to-point high-voltage dc transmission
In electric system, DC voltage usually is controlled with a converter station, another converter station controls active power.And works as and be expanded into multiterminal
DC transmission system, the control of DC grid voltage and the distribution of grid power will be cooperated by multiple converter stations to be completed, control method
Also it will become complicated.Currently, the control method of direct current system mainly includes master & slave control, voltage Boundary Control and the sagging control of voltage
System.
In recent years current research both domestic and external is also based on three of the above control program, and emphasis is directed to sagging control, expansion
Research work to the control of multi-terminal direct current transmission system converter station.Master & slave control is big in current multi-terminal HVDC transmission Practical Project
The method all used, its working principle is that the voltage of entire DC grid is controlled with a main converter station, other converter station controls
The power of port where making it.However, master & slave control to the performance requirement of main converter station and coupled AC network very
Height, power unusual fluctuation will all be undertaken by main converter station and its connected AC network in entire DC grid.When unusual fluctuation is excessive, hold
(1) easily occurs and exceeds converter station maximum capacity, (2) change the converter station power transmission direction, influence connected AC network.
And when main converter station breaks down, the voltage of entire DC grid will collapse immediately.Voltage Boundary Control is considered a kind of
Optimal control method based on master & slave control.It is equally that voltage is controlled by a converter station, other converter stations control power.Work as control
After the converter station of voltage processed reaches peak power output, this converter station will no longer control DC voltage, and will control voltage
Task transfers to another spare converter station to execute.However, in all only one converter stations of each moment in control DC grid
Voltage, it is limited to the ability for resisting the change of current station failure.Simultaneously as needing multiple changes of current when exchanging power voltage control
It is communicated between standing, the concussion of low frequency trend can be generated, easily cause more serious DC grid stability problem.Voltage it is sagging control be
In recent years the new method of one kind that industry experts scholar proposes, can solve asking in above-mentioned master & slave control and voltage Boundary Control
Topic.Voltage droop control method is a kind of control method for going to center, and the control of each converter station is mutually indepedent, does not need to communicate.
Its working principle is similar with the control of the frequency droop of AC network, and DC voltage will no longer be controlled so as to a fixed value, but
It is automatically adjusted within the scope of one according to the feedback of system.Each converter station will according to droop characteristic, co- controlling DC grid
Voltage, meanwhile, the power unusual fluctuation that each converter station will be shared in DC grid.When change of current station failure occurs, normal work is changed
Stream station can share the imbalance power generated by failure.And master & slave control is compared, the sagging control of voltage eliminates DC grid
Dependence to single converter station.Comparison with voltage Boundary Control, the sagging control of voltage will not generate the concussion of low frequency trend.However, with
Unlike the control of AC network frequency droop, the DC voltage of the sagging control of multi-terminal direct current transmission system voltage is not one
Global variable, DC voltage can be slightly different in each port of DC grid.The direct current of each converter station of multi-terminal direct current transmission system
Voltage is limited by topological structure and each DC line conductance of direct current system, need to meet Kirchhoff's second law (KVL).
The power transmitted through converter station, equal to the algebraical sum for each DC line delivering power being connected with the converter station.Therefore, design is each
The sagging control parameter of converter station is relatively difficult, it is common practice to referring to the working condition that converter station is stable under master & slave control
It designs one group of reference work point, the sagging control parameter of each converter station is designed further in accordance with reference work point.Each converter station
Sagging control is mutually indepedent, and sagging control parameter will not be adjusted according to the variation of system mode.Therefore, when the shape of DC grid
After state changes, the sagging control program before each converter station can change according to electric network state is continued to run, each converter station
It will be then in " inferior health " state with DC line, DC line overload is also easy to produce, copes with the problems such as failures are not strong.
Summary of the invention
The present invention provides a kind of methods for hierarchical control multi-terminal direct current transmission system regarding to the issue above, comprising:
Tier I acquires multi-terminal direct current transmission system alterating and direct current network data, according to electric network data to multi-terminal HVDC transmission system
System frequency auxiliary is supported and carries out concussion inhibition to multi-terminal direct current transmission system low frequency power；
Tier ii obtains the real work point and reference work point of the sagging control of multi-terminal direct current transmission system, comprising:
It determines multi-terminal direct current transmission system optimization aim and restrictive condition, conductance is determined according to optimization aim and restrictive condition
Matrix G and DC grid voltage vector V；
According to conductance matrix G and DC grid voltage vector V, the sagging control planning of the voltage of optimization aim is determined, indicate:
Wherein, ViVirtual voltage, P for optimization aim converter station iiActual power, β for optimization aim converter station iiFor
The sagging coefficient of optimization aim converter station i,For optimization aim converter station i the sagging control of voltage reference power andFor
Optimization aim converter station i the sagging control reference voltage of voltage；
Real work point (the P of optimization aim is determined according to formula (1)i,Vi) and reference work point
Layer III, according to the reference work of optimization aim pointObtain the sagging control of optimization aim converter station i
Parameter；
The control parameter includes: the upper voltage limit of optimization aim converter station iOptimization aim converter station i's
Lower voltage limitThe upper limit of the power of optimization aim converter station iWith the lower limit of the power of optimization aim converter station i
Formula (1) is extended to the sagging control formula of MTDC transmission system by Section IV layer, and formula is as follows:
Wherein, FiFor monotonic function；
Obtain converter station i signalWith the voltage signal V of converter station i DC side real-time measurementi-com, according to optimization aim reality
Border operating point (Pi,Vi) and optimization aim reference work pointAnd control parameter, execute the sagging control of MTDC transmission system
System.
Optionally, optimization aim includes: system maximal received power, minimum wire loss and maximum each component nargin.
Optionally, restrictive condition include: the current topological structure of system, each node power balance, each DC port voltage,
The output power of each new energy power station, the maximum power of each converter station, each AC system receive or issue the ability of power, respectively change
Flow the voltage restrictive condition at station and the maximum transfer capacity of each DC line.
Optionally, conductance matrix G is indicated are as follows:
Wherein, gijFor the direct current cables for connecting MTDC transmission system DC port i and MTDC transmission system DC port j
Electric conductivity value.
Optionally, conductance matrix G and DC grid voltage vector V can be used for indicating MTDC transmission system parameter；
The parameter includes: total line loss of MTDC transmission system, and formula is as follows:
Ploss=∑ gij·(Vi-Vj)2=VT·G·V (4)
The power of MTDC transmission system DC port and, formula is as follows:
The electric current of the DC line of MTDC transmission system, formula are as follows:
iij=gij·(Vj-Vi)。 (6)
The present invention also provides a kind of systems for hierarchical control multi-terminal direct current transmission system, comprising:
Acquisition module acquires multi-terminal direct current transmission system alterating and direct current network data, defeated to multiterminal element according to electric network data
Electrical system frequency auxiliary is supported and carries out concussion inhibition to multi-terminal direct current transmission system low frequency power；
First determining module obtains the real work point and reference work point of the sagging control of multi-terminal direct current transmission system, packet
It includes:
It determines multi-terminal direct current transmission system optimization aim and restrictive condition, conductance is determined according to optimization aim and restrictive condition
Matrix G and DC grid voltage vector V；
According to conductance matrix G and DC grid voltage vector V, the sagging control planning of the voltage of optimization aim is determined, indicate:
Wherein, ViVirtual voltage, P for optimization aim converter station iiActual power, β for optimization aim converter station iiFor
The sagging coefficient of optimization aim converter station i,For optimization aim converter station i the sagging control of voltage reference power andFor
Optimization aim converter station i the sagging control reference voltage of voltage；
Real work point (the P of optimization aim is determined according to formula (1)i,Vi) and reference work point
Second determining module, according to the reference work of optimization aim pointIt is sagging to obtain optimization aim converter station i
Control parameter；
The control parameter includes: the upper voltage limit of optimization aim converter station iOptimization aim converter station i's
Lower voltage limitThe upper limit of the power of optimization aim converter station iWith the lower limit of the power of optimization aim converter station i
Formula (1) is extended to the sagging control formula of MTDC transmission system by control module, and formula is as follows:
Wherein, FiFor monotonic function；
Obtain converter station i signalWith the voltage signal V of converter station i DC side real-time measurementi-com, according to optimization aim reality
Border operating point (Pi,Vi) and optimization aim reference work pointAnd control parameter, execute the sagging control of MTDC transmission system
System.
Optionally, optimization aim includes: system maximal received power, minimum wire loss and maximum each component nargin.
Optionally, restrictive condition include: the current topological structure of system, each node power balance, each DC port voltage,
The output power of each new energy power station, the maximum power of each converter station, each AC system receive or issue the ability of power, respectively change
Flow the voltage restrictive condition at station and the maximum transfer capacity of each DC line.
Optionally, conductance matrix G is indicated are as follows:
Wherein, gijFor the direct current cables for connecting MTDC transmission system DC port i and MTDC transmission system DC port j
Electric conductivity value.
Optionally, conductance matrix G and DC grid voltage vector V can be used for indicating MTDC transmission system parameter；
The parameter includes: total line loss of MTDC transmission system, and formula is as follows:
Ploss=∑ gij·(Vi-Vj)2=VT·G·V
The power of MTDC transmission system DC port and, formula is as follows:
The electric current of the DC line of MTDC transmission system, formula are as follows:
iij=gij·(Vj-Vi)。
Lifting system is received the ability of intermittent new energy power station transient output by the present invention, lifting system copes with direct current
The ability of the system failure and the loss of reasonably optimizing DC line.
The present invention solves extensive new energy power station and goes out fluctuation and each port receiving (supply) of AC/DC Power System
The nargin assignment problem of electric power, realizes in the same multi-terminal direct current transmission system, each converter station function based on hierarchical control
Rate-voltage dynamic adjustment performance.
Detailed description of the invention
Fig. 1 is a kind of method tier I schematic diagram for hierarchical control multi-terminal direct current transmission system of the present invention；
Fig. 2 is a kind of method tier ii schematic diagram for hierarchical control multi-terminal direct current transmission system of the present invention；
Fig. 3 is a kind of method layer III schematic diagram for hierarchical control multi-terminal direct current transmission system of the present invention；
Fig. 4 is a kind of method Section IV layer schematic diagram for hierarchical control multi-terminal direct current transmission system of the present invention；
Fig. 5 is a kind of analysis evaluation scheme of the method proposed adoption for hierarchical control multi-terminal direct current transmission system of the present invention
Figure；
Fig. 6 is a kind of method flow diagram for hierarchical control multi-terminal direct current transmission system of the present invention；
Fig. 7 is a kind of system construction drawing for hierarchical control multi-terminal direct current transmission system of the present invention.
Specific embodiment
Exemplary embodiments of the present invention are being described referring to the appended drawings, however, the present invention can use many different forms
Implement, and be not limited to the embodiment described herein, providing these embodiments is at large and fully disclose this
Invention, and the scope of the present invention is sufficiently conveyed to person of ordinary skill in the field.For the example being illustrated in the accompanying drawings
Term in property embodiment is not limitation of the invention.In the accompanying drawings, identical cells/elements use identical attached drawing
Label.
Unless otherwise indicated, term (including scientific and technical terminology) used herein has person of ordinary skill in the field
It is common to understand meaning.Further it will be understood that with the term that usually used dictionary limits, should be understood as and its
The context of related fields has consistent meaning, and is not construed as Utopian or too formal meaning.
The present invention provides a kind of methods for hierarchical control multi-terminal direct current transmission system, as shown in Figure 6, comprising:
Tier I acquires multi-terminal direct current transmission system alterating and direct current network data, according to electric network data to multi-terminal HVDC transmission system
System frequency auxiliary is supported and carries out concussion inhibition to multi-terminal direct current transmission system low frequency power；
As shown in Figure 1, the tier I of the method for the hierarchical control of multi-terminal direct current transmission system, effect is to realize alternating current-direct current system
System miscellaneous function, such as the auxiliary of AC system frequency is supported, the concussion of AC system low frequency power is inhibited etc., tier I needs
The data of alternating current-direct current power grid long period are acquired, are postponed higher.
Tier ii obtains the real work point and reference work point of the sagging control of multi-terminal direct current transmission system, comprising:
As shown in Fig. 2, the tier ii of the method for the hierarchical control of multi-terminal direct current transmission system, target is to pass through optimization
Algorithm calculates the reference work point of sagging control, and the data that tier ii needs to acquire full DC grid carry out analytical calculation, can produce
Raw communication delay.
Wherein, the optimal algorithm of tier ii of the present invention will fully consider the actual conditions of system operation, current according to system
State restrictive condition, establish calculate it is sagging control reference work point dynamic optimization algorithm, it is sagging to calculate each converter station
The reference work point of control.Its basic ideas is as follows.
Optimization aim is drafted are as follows: system maximal received power, minimum wire loss and maximum each component nargin.
Restrictive condition includes: the current topological structure of system, each node power balances, each DC port voltage need to meet base
That Hough voltage law, the output power of each new energy power station, the maximum power of each converter station, each AC system receive (sending)
The ability of power, the voltage restrictive condition of each converter station, the maximum transfer capacity of each DC line and other restrictive conditions.
Tier ii will use conductance matrix G and DC grid voltage vector V, establish the objective function and limit of optimization algorithm
Condition processed.Wherein, conductance matrix G for trace system topological structure and each DC line conductance, DC grid voltage to
It measures V and is used for each DC port voltage of trace system.
Conductance matrix:
Wherein, gijIndicate the electric conductivity value of the direct current cables of connection DC port i and DC port j.
Many parameters of MTDC transmission system can be described by G and V, such as:
Total line loss of direct current system:
Ploss=∑ gij·(Vi-Vj)2=VT·G·V (2)
Be input to each DC port power and:
The electric current of each DC line:
iij=gij·(Vj-Vi) (4)
Plan of the present invention uses MATLAB Optimization Toolbox optimization computation tool, calculates DC grid
The optimum operating voltage of each converter station, and thus calculate the reference work point of the sagging control of each converter station.
The sagging control established according to the above calculated reference work point, the voltage that will lead to controlled converter station are close
It or is more than rated maximum；Dynamic optimization algorithm needs the voltage for sagging control, and there are surpluses.Multi-terminal direct current transmission system
Voltage droop control method, the frequency droop control method from AC network.It is controlled in the frequency droop of AC network
In, as the power demand of node changes, frequency can be adjusted to corresponding big according to sagging control by the governor of generator
It is small, to adapt to the changed power of node.Similarly, in the sagging control of the voltage of DC grid, with the power of DC port
Demand changes, and voltage can be adjusted to response magnitude according to sagging control by inverter, is become with adapting to the power of DC port
Change.
But unlike AC network frequency, each port voltage of MTDC transmission system is all not quite similar: by direct current
The limitation of topological structure of electric and DC line conductance, the voltage of each DC port need to meet Kirchhoff's second law (KVL),
To guarantee current flowing.It therefore, will be extremely difficult if the reference voltage of the sagging control of mode design voltage with constant voltage.
Usual way is to allow system first according to master & slave control scheme, obtains one group of stable working condition, and be designed into as voltage
The reference work point of sagging control designs the other parameters of the voltage droop characteristic of each converter station further in accordance with reference work point.Most
The sagging control planning of the voltage mentioned in recent studies on development trend can be indicated greatly with the total relation of formula (1):
Wherein Vi、PiAnd βiIt respectively indicates: virtual voltage, actual power and the sagging coefficient of converter station i.WithPoint
Not Biao Shi: the reference power and reference voltage of the sagging control of the voltage of change of current i.
Real work point (the P of optimization aim is determined according to formula (1)i,Vi) and reference work point
Layer III, according to the reference work of optimization aim pointObtain the sagging control of optimization aim converter station i
Parameter；
The control parameter includes: the upper voltage limit of optimization aim converter station iOptimization aim converter station i's
Lower voltage limitThe upper limit of the power of optimization aim converter station iWith the lower limit of the power of optimization aim converter station i
Formula (1) is extended to the sagging control formula of MTDC transmission system by Section IV layer, and formula is as follows:
Wherein, FiFor monotonic function；
Obtain converter station i signalWith the voltage signal V of converter station i DC side real-time measurementi-com, according to optimization aim reality
Border operating point (Pi,Vi) and optimization aim reference work pointAnd control parameter, execute the sagging control of MTDC transmission system
System.
Section IV layer, the execution level including the sagging control of converter station, the layer are real-time control, are timely responded to.
Wherein, sagging Controlling model includes establishing according to each converter station under sagging control reference work point, current state
The restrictive condition of voltage and power establishes the optimization algorithm for calculating non-linear sagging control parameter.Non-linear sagging control mould
Type includes being bonded the characteristic of multi-terminal direct current transmission system, considers the feature that each converter station cooperates under different working condition.
As shown in figure 4, illustrate the sagging control total relation of the voltage of formula (1),Indicate reference work point,
(Pi,Vi) indicate that real work point, real work point would operate on established sag characteristics figure,AndThe respectively bound of the voltage of converter station i and power, these parameters need to meet ac and dc systems and the change of current
The restrictive condition of device.Real work point is in the sagging control line work of voltage that have passed through reference work point.Such as formula (1) and Fig. 4
Shown in power in the sagging control of voltage and voltage established according to linear relationship.
The present invention plans formula (1) and is extended to more general expression formula:
Wherein, FiIt is not limited to a control parameter, is also possible to a nonlinear control function.It is noted that
For the feedback control principle for meeting system, FiIt must be a monotonic function in its control range.
The present invention will propose the non-linear sagging controlling party of control multi-terminal direct current transmission system each converter station voltage and power
Method will be used as basic representation using formula (2).Reference work pointIt will be using by upper one layer of dynamic optimization
The result that algorithm calculates.
The minimum and maximum power operating point that can be transmitted according to reference work point and the converter station, sets up non-thread respectively
Property sagging control right half-court between characteristic equation between left half-court.Upper and lower two parts operation interval, sets up nonlinear function.With reference to
Operating pointFor upper one layer of optimization computation result.
As shown in figure 4, illustrating to establish the basic ideas of nonlinear droop control method, in the voltage and function of each converter station
Within the scope of the restriction of rate, it will be divided into according to reference work point and establish sagging control program between right half-court between left half-court, for knot
The dynamic optimization scheme of sagging control reference work point, the working performance of further lifting system are closed, proposed adoption is closely referring to
The variation of operating point, the variation corresponding voltage of power is smaller, and remote reference work point, the variation corresponding voltage of power changes greatly
Nonlinear Control scheme.
As shown in figure 4, generating control converter stationSignal, Vi-comTo believe in the voltage of converter station DC side real-time measurement
Number.
As shown in figure 5, the present invention utilizes calculating and emulation tool, to the dynamic of the sagging control reference work point of converter station
Optimization computation, proposed adoption MATLAB Optimization Toolbox optimization computation tool, to AC/DC Power System tide
Stream calculation proposed adoption PowerWorld simulation software, and it is imitative to be established in conjunction with Practical Project data according to calculation of tidal current for transient state
True to calculate, the Transient State Simulation Software of proposed adoption is PSCAD/EMTDC.
The present invention also provides a kind of systems 200 for hierarchical control multi-terminal direct current transmission system, as shown in fig. 7, packet
It includes:
Acquisition module 201 acquires multi-terminal direct current transmission system alterating and direct current network data, according to electric network data to multiterminal element
Transmission system frequency auxiliary is supported and carries out concussion inhibition to multi-terminal direct current transmission system low frequency power；
First determining module 202 obtains the real work point and reference work point of the sagging control of multi-terminal direct current transmission system,
Include:
It determines multi-terminal direct current transmission system optimization aim and restrictive condition, conductance is determined according to optimization aim and restrictive condition
Matrix G and DC grid voltage vector V；
Optimization aim includes: system maximal received power, minimum wire loss and maximum each component nargin.
Restrictive condition includes: the current topological structure of system, each node power balance, each DC port voltage, each new energy
The output power in source power station, the maximum power of each converter station, each AC system receive or issue the ability of power, each converter station
The maximum transfer capacity of voltage restrictive condition and each DC line.
The conductance matrix G of optimization aim is indicated are as follows:
Wherein, gijFor the direct current cables for connecting MTDC transmission system DC port i and MTDC transmission system DC port j
Electric conductivity value.
Conductance matrix G and DC grid voltage vector V can be used for indicating MTDC transmission system parameter；
The parameter includes: total line loss of MTDC transmission system, and formula is as follows:
Ploss=∑ gij·(Vi-Vj)2=VT·G·V
The power of MTDC transmission system DC port and, formula is as follows:
The electric current of the DC line of MTDC transmission system, formula are as follows:
iij=gij·(Vj-Vi)。
According to conductance matrix G and DC grid voltage vector V, the sagging control planning of the voltage of optimization aim is determined, indicate:
Wherein, ViVirtual voltage, P for optimization aim converter station iiActual power, β for optimization aim converter station iiFor
Sagging coefficient, the P of optimization aim converter station ii *For optimization aim converter station i the sagging control of voltage reference power andFor
Optimization aim converter station i the sagging control reference voltage of voltage；
Real work point (the P of optimization aim is determined according to formula (1)i,Vi) and reference work point
Second determining module 203, according to the reference work of optimization aim pointObtain optimization aim converter station i
Sagging control parameter；
The control parameter includes: the upper voltage limit of optimization aim converter station iOptimization aim converter station i's
Lower voltage limitThe upper limit of the power of optimization aim converter station iWith the lower limit of the power of optimization aim converter station i
Formula (1) is extended to the sagging control formula of MTDC transmission system by control module 204, and formula is as follows:
Wherein, FiFor monotonic function；
Obtain converter station i signalWith the voltage signal V of converter station i DC side real-time measurementi-com, according to optimization aim reality
Border operating point (Pi,Vi) and optimization aim reference work pointAnd control parameter, execute the sagging control of MTDC transmission system
System.
Lifting system is received the ability of intermittent new energy power station transient output by the present invention, lifting system copes with direct current
The ability of the system failure and the loss of reasonably optimizing DC line.
The present invention solves extensive new energy power station and goes out fluctuation and each port receiving (supply) of AC/DC Power System
The nargin assignment problem of electric power, realizes in the same multi-terminal direct current transmission system, each converter station function based on hierarchical control
Rate-voltage dynamic adjustment performance.
Claims (10)
1. a kind of method for hierarchical control multi-terminal direct current transmission system, the method, comprising:
Tier I acquires multi-terminal direct current transmission system alterating and direct current network data, according to electric network data to multi-terminal direct current transmission system frequency
Rate auxiliary is supported and carries out concussion inhibition to multi-terminal direct current transmission system low frequency power；
Tier ii obtains the real work point and reference work point of the sagging control of multi-terminal direct current transmission system, comprising:
It determines multi-terminal direct current transmission system optimization aim and restrictive condition, conductance matrix is determined according to optimization aim and restrictive condition
G and DC grid voltage vector V；
According to conductance matrix G and DC grid voltage vector V, the sagging control planning of the voltage of optimization aim is determined, indicate:
Wherein, ViVirtual voltage, P for optimization aim converter station iiActual power, β for optimization aim converter station iiFor optimization
The sagging coefficient of target converter station i,For optimization aim converter station i the sagging control of voltage reference power andFor it is excellent
Change the sagging control reference voltage of voltage of target converter station i；
Real work point (the P of optimization aim is determined according to formula (1)i,Vi) and reference work point
Layer III, according to the reference work of optimization aim pointObtain the sagging control parameter of optimization aim converter station i；
The control parameter includes: the upper voltage limit of optimization aim converter station iUnder the voltage of optimization aim converter station i
LimitThe upper limit of the power of optimization aim converter station iWith the lower limit of the power of optimization aim converter station i
Formula (1) is extended to the sagging control formula of MTDC transmission system by Section IV layer, and formula is as follows:
Wherein, FiFor monotonic function；
Obtain converter station i signalWith the voltage signal V of converter station i DC side real-time measurementi-com, according to the practical work of optimization aim
Make point (Pi,Vi) and optimization aim reference work pointAnd control parameter, execute the sagging control of MTDC transmission system.
2. according to the method described in claim 1, the optimization aim includes: system maximal received power, minimum line path loss
Consumption and maximum each component nargin.
3. according to the method described in claim 1, the restrictive condition includes: the current topological structure of system, each node function
Rate balance, each DC port voltage, the output power of each new energy power station, the maximum power of each converter station, each AC system connect
By or issue power ability, the voltage restrictive condition of each converter station and the maximum transfer capacity of each DC line.
4. according to the method described in claim 1, the conductance matrix G, indicates are as follows:
Wherein, gijFor the conductance of the direct current cables of connection MTDC transmission system DC port i and MTDC transmission system DC port j
Value.
5. according to the method described in claim 1, the conductance matrix G and DC grid voltage vector V can be used for indicating more
Hold direct current system parameter；
The parameter includes: total line loss of MTDC transmission system, and formula is as follows:
Ploss=∑gij·(Vi-Vj)2=VT·G·V (4)
The power of MTDC transmission system DC port and, formula is as follows:
The electric current of the DC line of MTDC transmission system, formula are as follows:
iij=gij·(Vj-Vi) (6) 。
6. a kind of system for hierarchical control multi-terminal direct current transmission system, the system, comprising:
Acquisition module acquires multi-terminal direct current transmission system alterating and direct current network data, according to electric network data to multi-terminal HVDC transmission system
System frequency auxiliary is supported and carries out concussion inhibition to multi-terminal direct current transmission system low frequency power；
First determining module obtains the real work point and reference work point of the sagging control of multi-terminal direct current transmission system, comprising:
It determines multi-terminal direct current transmission system optimization aim and restrictive condition, conductance matrix is determined according to optimization aim and restrictive condition
G and DC grid voltage vector V；
According to conductance matrix G and DC grid voltage vector V, the sagging control planning of the voltage of optimization aim is determined, indicate:
Wherein, ViVirtual voltage, P for optimization aim converter station iiActual power, β for optimization aim converter station iiFor optimization
The sagging coefficient of target converter station i,For optimization aim converter station i the sagging control of voltage reference power andFor it is excellent
Change the sagging control reference voltage of voltage of target converter station i；
Real work point (the P of optimization aim is determined according to formula (1)i,Vi) and reference work point
Second determining module, according to the reference work of optimization aim pointObtain the sagging control of optimization aim converter station i
Parameter；
The control parameter includes: the upper voltage limit of optimization aim converter station iUnder the voltage of optimization aim converter station i
LimitThe upper limit of the power of optimization aim converter station iWith the lower limit of the power of optimization aim converter station i
Formula (1) is extended to the sagging control formula of MTDC transmission system by control module, and formula is as follows:
Wherein, FiFor monotonic function；
Obtain converter station i signalWith the voltage signal V of converter station i DC side real-time measurementi-com, according to the practical work of optimization aim
Make point (Pi,Vi) and optimization aim reference work pointAnd control parameter, execute the sagging control of MTDC transmission system.
7. system according to claim 6, the optimization aim includes: system maximal received power, minimum line path loss
Consumption and maximum each component nargin.
8. according to right want 6 described in system, the restrictive condition includes: the current topological structure of system, each node power
Balance, each DC port voltage, the output power of each new energy power station, the maximum power of each converter station, each AC system receive
Or issue ability, the voltage restrictive condition of each converter station and the maximum transfer capacity of each DC line of power.
9. system according to claim 6, the conductance matrix G are indicated are as follows:
Wherein, gijFor the conductance of the direct current cables of connection MTDC transmission system DC port i and MTDC transmission system DC port j
Value.
10. system according to claim 6, the conductance matrix G and DC grid voltage vector V can be used for indicating more
Hold direct current system parameter；
The parameter includes: total line loss of MTDC transmission system, and formula is as follows:
Ploss=∑ gij·(Vi-Vj)2=VT·G·V
The power of MTDC transmission system DC port and, formula is as follows:
The electric current of the DC line of MTDC transmission system, formula are as follows:
iij=gij·(Vj-Vi)。
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