CN110504681A - Consider that stability transmission power containing LCC-VSC determines method and system - Google Patents
Consider that stability transmission power containing LCC-VSC determines method and system 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
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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]
Abstract
The invention discloses a kind of consideration stability transmission powers containing LCC-VSC to determine method and system, method includes: based on power supply and load condition, the method of operation before determining the failure of transmission system containing LCC-VSC is based on Operation Mode Selection incipient fault equipment, sets faulty equipment number as Kmax；Transmission system capital equipment fault type and fault point are sampled based on Monte Carlo；The equipment fault type obtained for sampling and fault point consider Fault Control mode, carry out the transmission system probabilistic stability index containing LCC-VSC and solve；Based on the probabilistic stability index sought, the power grid maximum transmission cross-section of permission is calculated；When counts are equal to Kmax, it is based on power grid maximum transmission cross-section, solves the power of grid power transmission containing LCC-VSC for considering stability.System includes: Influence factor analysis of earth module, Operation Mode Selection module, stability analysis emulation and computing module, human-computer interaction and data storage display module.
Description
Technical field
The present invention relates to field of power system more particularly to a kind of consideration stability transmission power containing LCC-VSC determination sides
Method and system.
Background technique
Traditional direct current transportation uses phased inverter (Line Commutated Converter, LCC), although transmission
Capacity is big, reliable for operation, but such as easy commutation failure of presence, reactive power consumption are big and cannot run on extremely weak AC system
The deficiencies of.Flexible high pressure direct current transportation based on voltage source converter (Voltage Source Converter, VSC) is to exchange
System strength does not require, and flexible operation, but the deficiency that there are switching losses is larger, cost is high.Use LCC simultaneously at present
Inverter and VSC inverter, to constitute Hybrid HVDC system (Hybrid-HVDC), such system structure is theoretically
The mutual supplement with each other's advantages of the two may be implemented, while avoiding the deficiency of two class inverters to the maximum extent[1-2].In order to determine power grid
Ability to transmit electricity, can need to consider power grid under various fault ' conditions keep stable, but the power grid transient state of the structure containing LCC-VSC is steady
Qualitative analysis and traditional power grid have relatively big difference, merit attention.
The electric system transmission power containing flexible DC transmission determines that method is required to concern operation stability really at present
It is fixed, the combined hybrid system transient characterisitics being concentrated mainly under simulation analysis different application scene.As document [3] proposes current source-
The machine-electricity transient model of the DC grid of voltage source converter mixed type, by electromagnetic transient simulation verifying to the shadow of ability to transmit electricity
It rings.Document [4] has studied the marine wind electric field alternating current-direct current grid-connected through modular multilevel converter type HVDC transmission system
Mixed connection electrical power system transient characteristic and Method of Stability Analysis, and then determine ability to transmit electricity.Document [5] is to marine wind electric field through flexibility
Direct current transportation grid-connected system consider the transient characterisitics research of ability to transmit electricity.To the alternating current-direct current system of Multi-end flexible direct current transmission
System, the dynamic response under the multiclass failures such as document [6] simulation analysis AC network accident, DC line fault, impact load
Characteristic, to verify the stability characteristic (quality) after Multi-end flexible direct current transmission access AC network.
With the expansion of electric system scale and increasingly complicated, the Transient Stability Evaluation calculating based on probability of running environment
Planning and operation ability to transmit electricity analysis for electric system have more and more important meaning.On the one hand, extensive power train
The safety and stability evaluation calculation amount of system is huge, needs good simulation process method；On the other hand, to assessment in engineering practice
Speed and precision requirement it is higher and higher.Therefore method is determined using novel transmission power for power grid containing LCC-VSC, solved
The problem of certainly network load and renewable energy power generation uncertainty are brought promotes the calculating effect of grid stability assessment algorithm
Rate, alleviating the contradiction even being eliminated between computational accuracy and speed becomes a very urgent task.
Summary of the invention
The present invention provides a kind of consideration stability transmission powers containing LCC-VSC to determine method and system, can effectively mention
Stabilization of power grids analysis efficiency of the power grid containing LCC-VSC under the random cases such as renewable energy access, failure generation, load is risen,
And then the total transfer capability when guaranteeing power grid operation is obtained, it is described below:
A kind of consideration stability transmission power containing LCC-VSC determines method, the described method comprises the following steps:
Obtain DC side and the control mode for exchanging side and breaking down in the transmission system containing LCC-VSC；Based on Meng Teka
System loading and renewable energy power generation are sampled before failure occurs for sieve；
Based on power supply and load condition, the method for operation before determining the failure of transmission system containing LCC-VSC is based on the method for operation
Incipient fault equipment is selected, sets faulty equipment number as Kmax；
Transmission system capital equipment fault type and fault point are sampled based on Monte Carlo；It is obtained for sampling
Equipment fault type and fault point consider Fault Control mode, carry out the transmission system probabilistic stability index containing LCC-VSC and ask
Solution；Based on the probabilistic stability index sought, the power grid maximum transmission cross-section of permission is calculated；
When counts are equal to Kmax, it is based on power grid maximum transmission cross-section, solve consideration stability contains LCC-VSC
Grid power transmission power.
Wherein, the method also includes:
Construct the transmission system model containing LCC-VSC, the principal element of analyzing influence system stability.
Further, described based on the probabilistic stability index sought, the power grid maximum transmission cross-section for calculating permission is specific
Are as follows:
By adjusting power grid sending end and receiving end generator output, change the variation of electrical grid transmission power, verify current failure,
Transient stability is carried out to analysis, and obtains the section tidal current limit, and then obtains the transmission power of power grid；
Based on transient stability failure probability index, solves and trusted with the former dual interior point of multistep predictive modeling
Linearisation increment Delta x in domain, by xkIt is updated toAccording to each adjustable generator adjustment amount bound constraint come
Decide whether to receive new iteration point, and in pointPlace executes trend and stability Calculation, obtains inequality constraints state point xk+1；
According to Transient Stability Criterion amount adjust next iteration needed for trusted zones adjust radius, new iteration point again
Trend and stability Calculation are carried out, constantly repeats above procedure until meeting section calculation required precision, state point x is saved and exits
This subfunction.
A kind of consideration stability transmission power containing LCC-VSC determines system, the system comprises:
Operation Mode Selection module breaks down for obtaining in the transmission system containing LCC-VSC DC side with side is exchanged
Control mode；System loading and renewable energy power generation are sampled before failure is occurred based on Monte Carlo；Based on power supply
And load condition, the method for operation before determining the failure of transmission system containing LCC-VSC are set based on Operation Mode Selection incipient fault
It is standby, faulty equipment number is set as Kmax；Transmission system capital equipment fault type and fault point are taken out based on Monte Carlo
Sample；
Stability analysis emulation and ability to transmit electricity computing module, equipment fault type and failure for being obtained for sampling
Point considers Fault Control mode, carries out the transmission system probabilistic stability index containing LCC-VSC and solves；Based on the probability sought
Stability indicator calculates the power grid maximum transmission cross-section of permission；It is disconnected based on the transmission of electricity of power grid maximum when counts are equal to Kmax
Face solves the power of grid power transmission containing LCC-VSC for considering stability.
Further, the system also includes:
Influence factor analysis of earth module, the hybrid AC/DC power transmission systems original part model analysis function comprising LCC-VSC,
Parameter setting function.
Further, the system also includes:
Human-computer interaction and data store display module, include parameter and set-up function, and calculating process and result save function,
Document report generation function.
The beneficial effect of the technical scheme provided by the present invention is that:
(1) present invention is for the total transfer capability problem in the case of guaranteeing power grid operation, in implementation process, power grid
It is huge, especially containing the power grid of LCC-VSC, it is related to each class component such as alternating current-direct current, total transfer capability solves complicated；It will contain
The power grid of LCC-VSC is parsed, while the random case of network load and power supply is carried out scene reduction, according to each peace
Full problem, every accident and each element calculate, and the risk analysis to each element can be combined into whole wind
Danger assessment, increases the flexibility of analysis, and improve analysis efficiency；
(2) present invention considers the load before failure occurs and renewable energy power generation is uncertain, Operation of Electric Systems
The features such as the occurrence type of mode and fault disturbance, moment, and probability analysis is carried out based on Monte Carlo method, really with tradition
Qualitative safety evaluation method is compared: being avoided and is only paid attention to most serious, most believable accident, calculated result seems overly conservative and lacks
Point.
Detailed description of the invention
Fig. 1 is to consider that stability transmission power containing LCC-VSC determines the flow chart of method；
Fig. 2 is the both ends LCC-VSC Hybrid HVDC system main wiring diagram；
Fig. 3 is section transmission limit Interpolation Principle schematic diagram；
Fig. 4 is the structural schematic diagram for considering stability grid power transmission containing LCC-VSC power solving system.
Specific embodiment
To make the object, technical solutions and advantages of the present invention clearer, embodiment of the present invention is made below further
Ground detailed description.
On the basis of carrying out the running state analysis of transmission system containing LCC-VSC, join probability carries out the embodiment of the present invention
The uncertain Monte Carlo sampling in source, net, lotus, quantitative evaluation power system transient stability, and then obtain and guarantee stabilization of power grids fortune
Power grid maximum transmission power in row situation.
As shown in Figure 1, a kind of consideration stability transmission power containing LCC-VSC provided in an embodiment of the present invention determines method,
Specifically includes the following steps:
101: transmission system model of the building containing LCC-VSC, the principal element of analyzing influence system stability；
102；In conjunction with the principal element of system stability, determine in the transmission system containing LCC-VSC DC side with exchange side
The control mode to break down；
103: system loading and renewable energy power generation are sampled determination before failure is occurred based on Monte Carlo；
104: being based on power supply and load condition, the method for operation before determining the failure of transmission system containing LCC-VSC；
105: being based on Operation Mode Selection incipient fault equipment, set faulty equipment number as Kmax；And set counts k
=1；
106: transmission system capital equipment fault type, fault point, fault moment being sampled based on Monte Carlo；
107: the equipment fault type obtained for sampling and fault point consider Fault Control mode, carry out containing LCC-VSC
Transmission system probabilistic stability index solve；
108: based on the probabilistic stability index sought, calculating the power grid maximum transmission of electricity trend section of permission；
109: judging whether k is equal to Kmax, if so, continuing to execute step 110；Otherwise k=k+1 is enabled, and is gone to step
106；
110: each power grid maximum transmission of electricity trend section based on acquisition solves and considers that the power grid containing LCC-VSC of stability is defeated
Electrical power；
111: solution procedure terminates, and saves system stability analysis result.
What it is for important step is that embodiment and detailed process are illustrated.
One, transmission system model and control mode containing LCC-VSC are constructed
Build the transmission of electricity of the both ends containing LCC-VSC model, and with actual control protection hardware platform progress interface, to containing
The transmission system control strategy of LCC-VSC, power transmission efficiency etc. are analyzed.
Transmission system containing LCC-VSC is made of 2 two converter stations in end 1 and end in embodiment, equipment composition and measuring point arrangement
As shown in Figure 2.The design of analogue system has the following characteristics that (1) end 1 is customary DC LCC converter station, and end 2 is flexible direct current
VSC converter station.(2) Hybrid HVDC system uses complete bipolar design, and pole 1, pole 2 can individually complete power conveying.(3) it holds
1LCC converter station is only used as converting plant to export dc power, and end 2VSC converter station can work in rectification mode, inverter mode or quiet
Only synchronous compensator (Static Synchronous Compensator, STATCOM) mode.
For traditional extra-high voltage DC transmission system, inverter side is easy to happen in the case where exception occurs in alternating voltage and changes
Mutually failure, commutation failure will seriously affect AC system stability, in some instances it may even be possible to cause the large area of regional power grid disconnected
Electrification.And the flexible HVDC transmission system based on wholly-controled device, because there is no commutation failure, not needing reactive power
Compensation device and it can voluntarily turn off the features such as not needing additional commutation voltage.
The Different Effects of rectification side fault in ac transmission system and inverter side fault in ac transmission system to direct current system, implementation process
In, need to comb the influence factor of the commutation process of direct current system inverter, the mechanism of commutation failure and commutation failure, typically
It include: the reduction that (1) rectification side fault in ac transmission system will lead to DC voltage and electric current, direct current transmission power reduces, idle to disappear
Consumption increases, and serious rectification side failure may cause system shutdown；
(2) inverter side fault in ac transmission system will affect commutation voltage, and commutation voltage declined senior general and causes inverter commutation
Failure leads to DC voltage decline, DC current increase, transmission power reduction and converter transformer DC magnetic bias aggravation etc. no
Good consequence；
(3) immediate cause that commutation failure occurs is off that angle is too small to cause commutation nargin insufficient；
(4) the commutation voltage decline, DC current increase of inverter, inverter side fault in ac transmission system asymmetry, transient state mistake
Journey or harmonic wave cause Trigger Angle in commutation voltage wave distortion and control system or shutdown angle instruction value it is too small will increase it is inverse
Become the probability of side commutation failure；
(5) place and severity that the intensity of AC system, AC fault occur can all influence DC transmission system
The generation of commutation failure.
Two, the method for operation before the failure of transmission system containing LCC-VSC is determined
Grid topology and randomly selecting for Generator Status can be obtained with state sampling method.System loading is at any time
Between and change, due to the non-concurrent property of load and network constraint and other factors, maximum load on a certain route is horizontal
The system peak load period might not be appeared in.In the probability assessment of transient stability, multistage level load model can be used
Concept[7], i.e., based on the probability distribution of system loading, provide the probability of each load level.Bus should be passed through in assessment
The relations of distribution between load prepare the flow data under each system load level, and wherein the bus load relations of distribution can basis
The load curve of substation obtains.
If the common method of operation of system has nmKind, the probability that i-th kind of method of operation occurs is Pr(Ai), do not consider other
The method of operation then has:
If being only concerned system under certain method of operation keeps stable probability, there is Pr (A)=1 (that is, nm=1).
For the convenience to study a question, the uncertain of power load distributing is not considered when carrying out probabilistic transient stability index analysis
Property influence, and assume mutually indepedent and mutually exclusive between different faults (event).
In the combined hybrid system rectification side containing LCC-VSC, control by constant current control, current limiting low-voltage link and αminLimitation three
Part forms.The purpose of constant current control link is to maintain direct current system electric current constant.The effect of current limiting low-voltage link is mainly
A possibility that reduction commutation failure occurs helps to maintain alternating voltage in the system failure, and help direct current system is in exchange or directly
Fast quick-recovery after flowing failure.αminLimitation is that have enough voltage on preceding valve to guarantee to trigger.Inverter side control system is by fixed
Hold-off angle control, constant current control, current deviation controlling unit and current limiting low-voltage link composition.Under normal circumstances, angle is turned off surely
Control is the main controlling unit of inverter side, to maintain fixed shutdown angle.When rectification side jumps to α from constant current control modemin
When unrestricted model, inverter side constant current control link can be selected the controlling unit as inverter side, maintain direct current system electric current
It is constant.
Three, system loading and generating state before selection failure occurs (containing renewable energy and tradition fire, water, nuclear power)
The load of electric system has uncertainty, needs given load based on historical load situation according to different level
It is classified, and is sampled using the direct sampling technique of discreteness distribution, do not know workload demand amount LσIt can be obtained by following formula
:
Wherein, ξ is equally distributed random number on [0,1].I is the general of load level corresponding to ξ load level of sampling
Rate density classification number.δLiFor i-stage load level LiProbability, seek formula be δLi=Ti/ T, TiFor i-stage load level
Time span, T=∑ TiFor the total length of time of load curve.
Similarly, controllable class distributed generation resource uses binary states (operation and stoppage in transit) model in the power supply set of electric system,
Maximum generation output power is determined by available installed capacity, but has randomness.It generates electricity for the intermittent renewable energy, operation
S under statei=1, s under stoppage in transit statei=0.The failure rate of controlled distribution formula power supply and repair time distribution, are united by history respectively
Count acquisition.In the case of isolated island, the available total power generation P of power gridDGIt is obtained by following formula:
Wherein, PUCiFor the sampling generated energy of i-th in power grid uncontrollable distributed generation resource, GUCFor uncontrollable point in power grid
Cloth power supply set；PCiFor the power generation capacity of i-th of controllable electric power in power grid, siFor the operating status of controlled distribution formula power supply,
GCFor controllable electric power set, including thermoelectricity, Hydropower Unit etc. in power grid.
Four, transmission system capital equipment fault type is sampled based on Monte Carlo Method
By taking commutation failure as an example, Probabilistic Analysis is carried out.Factor relevant to commutation failure mainly has: change of current bus electricity
Zero crossing phase shift, transient process and the AC system of commutation voltage when pressure, DC current, gating advance angle, unbalanced fault
Spectral characteristic etc..Random sampling is carried out based on probability nature of the Monte Carlo to electric system capital equipment element
(1) during Monte-Carlo Simulation, part uncertain parameter model can be obtained by historical data, or be assumed to
One probability-distribution function.Such as assume that system is made of m element, SkThe state of representation element k, then x=(S1,…,Sk,…,
Sm).System mode x depend on system element combinations of states, as long as therefore determine each element state, system mode x
Also just corresponding to determine.
System mode can carry out random sampling by the probability nature to electric system capital equipment element to obtain, and
Being uniformly distributed to describe between [0,1] then can be used in the probability nature of element.Assuming that each element only it is faulty and
It runs two states and element fault is event independent of each other, enable PFkIndicate element k without validity, extract a value
Section is the uniform random number U of [0,1]k, then have:
Extract m random number (U1,…,Uk,…,Um), determine system mode x=(S1,…,Sk,…,Sm), it repeats above-mentioned
Process NS times can then obtain the set X=(x comprising NS system mode sample1,x2,…,xNS), the sample in X does not have
There is uniqueness, it is understood that there may be multiple duplicate system modes.
Five, the transmission system probabilistic stability index containing LCC-VSC is carried out to solve
The final goal of Probabilistic transient stability assessment is to obtain the reliability index of system quantifies, is electric power
The planning and operation of system provide data and support, specific as follows using two than major stability indicator:
(1) power system transient stability failure probability POTS (Probabilistic of Transient
Stability), calculation formula is as follows:
In formula, NS is the number of system stochastic regime, FPOTS(xi) indicate system in stochastic regime xiThe transient state of lower system is steady
Qualitative analysis unstability is as a result, F in the case of unstabilityPOTS(xi)=1, F under stable casePOTS(xi)=0.
(2) if the reliability for the system of considering, can also use loss of load probability LOLP (Loss of Load
Probability there is the probability of power-off event, calculation formula in expression system in) index are as follows:
In formula, FLOLPFor testing function corresponding with LOLP, determined as the following formula by system stochastic regime vector:
Transient stability appraisal procedure based on various methods is equally the key that entire algorithm analysis efficiency.It solves at present
The analysis method of Solving Power System Transient Stability Problem substantially there are three types of: time-domain-simulation method (Time Domain Simulation
Method), direct method (Direct Method) and the hybrid algorithm (Hybrid Method) for combining both fronts.
Hybrid algorithm is a kind of practical power system transient stability analysis method that recent two decades grow up.It basic
It is characterized in combining Method of Numerical Simulation and direct method, not only model is adaptable, but also can obtain reflection system transient modelling
The quantitative target of degree of stability.Thus it and has been developed once coming out just by the most attention of researchers at home and abroad
Applied in the online stability analysis of practical large-scale modern power systems.
In practice process, Potential Energy Boundary Surface Method can be used and carry out transient stability analysis, determine critical clearing time and stabilization
Nargin, if possible generating system unstability, then take corresponding remedial measure, dynamic cutting load caused by calculating because of Transient Instability.
After adopting remedial measures, if system is restored to stablize, system is in controllable instability status, counts dynamic cutting load amount；Such as
Fruit system still unstability after adopting remedial measures, then uncontrollable unstability occurs for system.
Six, based on the probabilistic stability index sought, the power grid maximum transmission cross-section of permission is calculated.
(1) it is constrained according to network system parameter, operating condition and operation, takes a typical operation modes, calculate working as section
Preceding trend, data-in library；
(2) it under current trend, concentrates failure to carry out multilayer output feedback network one by one catastrophe failure, finds out most serious event
Barrier, is set as most serious failure for current failure, exits and finds most serious failure subfunction.Failure in fault set is stabilization
When, visual angle radius index it is maximum be most serious failure, there is jitterbug, regard normalize minimum kinetic energy index it is maximum as
Most serious failure[8], result is stored in volatile data base.
(3) it according to the minimum kinetic energy/angular radius index obtained in step (2), generates electricity by adjusting power grid sending end and receiving end
Machine power output, changes the variation of electrical grid transmission power, verifies current failure, carries out transient stability to analysis, and obtains section tide
Flow the limit.Use the section tidal current limit calculation optimization mathematical modulo based on optimal load flow (Optimal Power Flow, OPF)
Type can be described as:
In formula, objective function is the feeding section S and active transimission power P by all interconnections between electric region RkmSummation
Maximum, the value are the function of power system transient stability failure probability POTS, and x is system control variables and state variable, and control becomes
Amount includes sending the controlled variable of the adjustable generator of receiving end (load), and state variable is the distribution of system load flow state；PkmFor take it is pre-
The Load flow calculation function for keeping system stable after anti-control and emergent control, is described as Pkm=fOPFIt (POTS), can be by solving trend
It obtains.It include power flow equation equality constraint and inequality constraints in formula (8), power flow equation equality constraint is to give in the S of sending end region
Total active (idle) adjustment amount of fixed one or a set of generator (load) node and by electric region R give generator
The adjustment amount of (load) node is equal；Inequality constraints be system transient stability security constraint and element operation limit value about
Beam.
(4) the section tidal current limit in comprehensive various situations, obtains the transmission power of power grid.
Based on power system transient stability failure probability index POTS, solved with the former dual interior point of multistep predictive modeling
The linearisation increment Delta x in trusted zones is obtained, by xkIt is updated toIt is adjusted according to each adjustable generator (load)
Bound constraint is measured to decide whether to receive new iteration point (if out-of-limit, taking its limiting value), and in pointPlace executes tide
Stream and stability Calculation, are strictly met the inequality constraints state point x of formula (8)k+1, according under the adjustment of Transient Stability Criterion amount
Trusted zones needed for an iteration adjust radius.Trend and stability Calculation are re-started in new iteration point, is constantly repeated above
Process is until meeting section calculation required precision, saving state point x and exiting this subfunction.
The signal of section transmission limit Interpolation Principle is as shown in Figure 3.The section limit is calculated using based on Trust Region Interior Point Method
OPF algorithm, the algorithm only consider the linear programming subproblem of adjustment amount in a neighborhood of current iteration point, this is to be based on
The principle that the approximate function (such as Taylor series expansion) of any model all only just coincide with original function in part well,
Therefore the Trust Region Interior Point Method being based on approaches background with very strong.
Seven, using the law of large numbers and central-limit theorem in probability theory, the power grid containing LCC-VSC for considering stability is obtained
Transmission power.
The law of large numbers guarantees that after extracting enough samples, the estimated value that Monte Carlo method obtains is converged on wait ask
The true value of amount；Central-limit theorem then provides theoretical foundation to analyze the calculating error of Monte Carlo method, if F (x) is indicated
Certain stability indicator test function using system mode x as independent variable；WithIndicate the sample standard deviation of random function F (x)
Value, valuation is available to be expressed from the next:
Uncertainty can be indicated by the sample variance of formula (9):
Wherein,Uncertainty it is directly proportional to variance V (F) of F (x), be inversely proportional with sample size NS.In reality
In, sample averageUncertainty usually indicated with coefficient of variation β:
After being often drawn into a failure system state, state sampling method updates stability indicator, while calculating coefficient of variation
β, if β is less than preparatory setting value, then it is assumed that reach computational accuracy, can stop calculating, therefore variance reduction technology is taken
It reduces V (F), it is possible to reduce sample number NS, so as to shorten the time is calculated.
Using the law of large numbers and central-limit theorem in probability theory, obtains and consider that the power grid containing LCC-VSC of stability is defeated
Electrical power.
PTrans=minmax f (β x) (12)
A kind of consideration stability transmission power containing LCC-VSC determines system, and referring to fig. 4, which includes:
Operation Mode Selection module breaks down for obtaining in the transmission system containing LCC-VSC DC side with side is exchanged
Control mode；System loading and renewable energy power generation are sampled before failure is occurred based on Monte Carlo；Based on power supply
And load condition, the method for operation before determining the failure of transmission system containing LCC-VSC are set based on Operation Mode Selection incipient fault
It is standby, faulty equipment number is set as Kmax；Transmission system capital equipment fault type and fault point are taken out based on Monte Carlo
Sample；
Stability analysis emulation and ability to transmit electricity computing module, equipment fault type and failure for being obtained for sampling
Point considers Fault Control mode, carries out the transmission system probabilistic stability index containing LCC-VSC and solves；Based on the probability sought
Stability indicator calculates the power grid maximum transmission cross-section of permission；It is disconnected based on the transmission of electricity of power grid maximum when counts are equal to Kmax
Face solves the power of grid power transmission containing LCC-VSC for considering stability.
Further, the system further include:
Influence factor analysis of earth module, the hybrid AC/DC power transmission systems original part model analysis function comprising LCC-VSC,
Parameter setting function；
Human-computer interaction and data store display module, include parameter and set-up function, and calculating process and result save function,
Document report generation function.
The embodiment of the present invention to the model of each device in addition to doing specified otherwise, the model of other devices with no restrictions,
As long as the device of above-mentioned function can be completed.
It will be appreciated by those skilled in the art that attached drawing is the schematic diagram of a preferred embodiment, the embodiments of the present invention
Serial number is for illustration only, does not represent the advantages or disadvantages of the embodiments.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all in spirit of the invention and
Within principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.
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Claims (6)
1. a kind of consideration stability transmission power containing LCC-VSC determines method, which is characterized in that the method includes following steps
It is rapid:
Obtain DC side and the control mode for exchanging side and breaking down in the transmission system containing LCC-VSC；Based on Monte Carlo pair
System loading and renewable energy power generation are sampled before failure occurs；
Based on power supply and load condition, the method for operation before determining the failure of transmission system containing LCC-VSC is based on Operation Mode Selection
Incipient fault equipment sets faulty equipment number as Kmax；
Transmission system capital equipment fault type and fault point are sampled based on Monte Carlo；The equipment obtained for sampling
Fault type and fault point consider Fault Control mode, carry out the transmission system probabilistic stability index containing LCC-VSC and solve；
Based on the probabilistic stability index sought, the power grid maximum transmission cross-section of permission is calculated；
When counts are equal to Kmax, it is based on power grid maximum transmission cross-section, solves and considers that the power grid containing LCC-VSC of stability is defeated
Electrical power.
2. a kind of consideration stability transmission power containing LCC-VSC according to claim 1 determines method, which is characterized in that
The method also includes:
Construct the transmission system model containing LCC-VSC, the principal element of analyzing influence system stability.
3. a kind of consideration stability transmission power containing LCC-VSC according to claim 1 determines method, which is characterized in that
It is described based on the probabilistic stability index sought, calculate the power grid maximum transmission cross-section of permission specifically:
By adjusting power grid sending end and receiving end generator output, change the variation of electrical grid transmission power, verify current failure, carries out
Transient stability obtains the section tidal current limit to analysis, and then obtains the transmission power of power grid；
Based on transient stability failure probability index, solve to obtain in trusted zones with the former dual interior point of multistep predictive modeling
Linearisation increment Delta x, by xkIt is updated toIt is determined according to each adjustable generator adjustment amount bound constraint
Whether new iteration point is received, and in pointPlace executes trend and stability Calculation, obtains inequality constraints state point xk+1；
Trusted zones needed for adjusting next iteration according to Transient Stability Criterion amount adjust radius, re-start in new iteration point
Trend and stability Calculation constantly repeat above procedure until meeting section calculation required precision, save state point x and exit this son
Function.
4. a kind of consideration stability transmission power containing LCC-VSC determines system, which is characterized in that the system comprises:
Operation Mode Selection module, the control for obtaining DC side in the transmission system containing LCC-VSC with exchanging side and break down
Mode processed；System loading and renewable energy power generation are sampled before failure is occurred based on Monte Carlo；Based on power supply and bear
Lotus state, the method for operation before determining the failure of transmission system containing LCC-VSC, is based on Operation Mode Selection incipient fault equipment, if
Determining faulty equipment number is Kmax；Transmission system capital equipment fault type and fault point are sampled based on Monte Carlo；
Stability analysis emulation and ability to transmit electricity computing module, equipment fault type and fault point for obtaining for sampling, are examined
Consider Fault Control mode, carries out the transmission system probabilistic stability index containing LCC-VSC and solve；Based on the probabilistic stability sought
Index calculates the power grid maximum transmission cross-section of permission；When counts are equal to Kmax, it is based on power grid maximum transmission cross-section, is asked
Solution considers the power of grid power transmission containing LCC-VSC of stability.
5. a kind of consideration stability transmission power containing LCC-VSC according to claim 4 determines system, which is characterized in that
The system also includes:
Influence factor analysis of earth module, the hybrid AC/DC power transmission systems original part model analysis function comprising LCC-VSC, parameter
Function is set.
6. a kind of consideration stability transmission power containing LCC-VSC according to claim 4 determines system, which is characterized in that
The system also includes:
Human-computer interaction and data store display module, include parameter and set-up function, and calculating process and result save function, document
Report generation function.
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