CN104281978A - Available transmission capacity calculation method based on probabilistic power flow - Google Patents

Abstract

The invention relates to an available transmission capacity calculation method based on the probabilistic power flow. According to the method, the probabilistic ATC of a probabilistic power flow calculating system is used, and the calculated amount of the method is greatly reduced compared with that of a simulation method, so that the calculating speed of the system probabilistic ATC is increased, and the calculating speed of AQTC is increased. The concepts of transmission element ATC and system ATC influence factors of the transmission element ATC are raised, transmission elements are sequentially added to a power system according to the sequence of the influence factors from large to small, more influences of the transmission elements are considered in a system probabilistic ATC result, the deviation between the result and actual system probabilistic ATC expectation is gradually reduced, the requirement for the probabilistic ATC calculation accuracy of the system is met, and the requirement for the AQTC calculation accuracy is met. Thus, the available transmission capacity calculation method can be widely applied to the fields of probabilistic available electric quantity transmission capacity calculation and probabilistic available transmission capacity calculation.

Description

A kind of Calculation of Available Transfer Capability method based on Probabilistic Load Flow

Technical field

The present invention relates to a kind of available conveying electricity computing method, particularly about a kind of Calculation of Available Transfer Capability method based on Probabilistic Load Flow.

Background technology

Wind-powered electricity generation, as clean regenerative resource, in today that energy crisis is increasingly serious, obtains development energetically.But, along with the continuous expansion of wind-electricity integration scale, wind energy turbine set abandons the universal phenomenon that wind becomes operation of power networks just gradually.Because the interregional resource complementation of China is with the obvious advantage, by coordinating on a large scale to give full play to the complementary effect that interregional load avoids the peak hour between wrong paddy effect, power supply architecture, thus the regenerative resources such as wind-powered electricity generation of farthest dissolving, so wind-powered electricity generation needs to carry out long-distance sand transport across multi-region electric network.Generally speaking, the production schedule of electricity power enterprise is in the mode of annual electricity, is provided by higher authority; And wind power is very strong in short-term uncertainty, but there is certain rule on long terms, can more adequately be predicted.Therefore, wind-powered electricity generation transaction is more suitable for signing contract with long period yardstick.The quantity of wind-powered electricity generation transaction, not only relevant with received quantity with the wind energy quantity that both parties can provide, also depend on the transport capacity of approach electrical network.Therefore, how to determine the quantity of the available conveying wind-powered electricity generation of electrical network between both parties, namely determining the available power transport capacity (Available Quantity Transfer Capability, AQTC) between both parties, is one of key issue urgently to be resolved hurrily before both sides conclude the business.

So-called available power transport capacity (AQTC), refers to actual physics power transmission network at the appointed time residue and can be used for the electricity transport capacity that business uses in section.The concept of existing available transmission capacity (Available Transfer Capability, ATC) refers to remaining in actual physics power transmission network, to can be used for business use transmission capacity.Both compare, although the two is all available transport capacitys of reflection electrical network, what ATC reflected is power, and AQTC refers to electricity.

The influence factor of AQTC is a lot, the generation schedule in the such as cycle, load prediction, Unit Combination, turnaround plan etc., therefore its computing method are comparatively complicated, and is difficult to accurate Calculation, does not also have the calculating AQTC method of relative maturity at present.And use for reference existing ATC algorithm, a thinking can be provided for the calculating of AQTC: within the minor cycle that changes of operating modes is little, choose a typical way, the uncertainty of discontinuity surface when utilizing each in this cycle of probability simulation of ATC.Once larger change occurs the method for operation, just again choose typical way, calculate the probability ATC under new typical way.Finally, the probability ATC under each typical way and time scale are weighted, obtain macrocyclic available conveying electricity.

Choose typical way obtained good application in Practical Project, staff rule of thumb, finds out and comparatively ripe, easy chooses mode, such as summer maximum mode, summer minimum mode, winter maximum mode, winter minimum mode.But the calculating of probability ATC still also exists some shortcomings.At present, the computing method for probability available transmission capacity (probability ATC) mainly comprise following a few class:

(1) based on the algorithm of stochastic programming: in the process calculating ATC, first use SPR (two-stage Stochastic Programming with Recourse) method by discrete variable serialization, subsequently according to the result of calculation of SPR, use CCP (Chance Constrained Programming) method process continuous variable, try to achieve the ATC value under probability meaning.Because the method has used the process of discrete variable and continuous variable in computation process, so computing velocity is not very desirable.

(2) enumerative technique; The enumerative technique that later stage proposes is that enumerating of system state is combined calculating ATC with optimized algorithm.When calculating ATC, if the catastrophic failure of this system is less, then the method is relatively effective, but for the electric system of reality, the exponential time characteristic of enumerative technique still limits its application, and the medium-term and long-term ATC that really effectively cannot process Iarge-scale system calculates.

(3) based on the algorithm of Monte-Carlo Simulation: application Monte Carlo method is sampled to system state.The method can process the uncertain factor of huge number in actual electric network easily, and its computing time does not connect the increase of complexity with system scale or network and sharply increases, and is apply a kind of computing method very widely.But, in order to ensure precision, frequency in sampling during emulation is thousands of, and institute is very consuming time in this way, is difficult to ensure counting yield.

(4) based on the algorithm of Bootstrap: this method is applied to during long-term ATC calculates, the market information (the exerting oneself of such as generator, node load level etc.) that can make full use of nearest a period of time removes the sample as estimating.But, as a kind of emerging algorithm, the uncertainty (random fault etc. of such as power transmission line) of some network parameter can't be processed well, need further improvement.

(5) based on the ATC computing method of probability: document Lei Dong, Saifeng Li, Yihan Yang, Hai Bao.Asia-Pacific Power and Energy Engineering Conference (APPEEC2010), utilize Probabilistic Load Flow in 2010 " The Calculation of Transfer Reliability Margin Based on the Probabilistic Load Flow ", after taking into full account TRM and CBM two kinds of nargin, calculate to obtain ATC.Although speed significantly improves, only considered a bottleneck circuit, have ignored the probability impact of other transmission of electricity element, make the computational accuracy of this algorithm be difficult to be met.

In sum, in existing probability ATC computing method, method (1)-(4) model is too complicated, calculates too consuming time; (5) although computing velocity ensured, consider bottleneck condition very few, precision is inadequate.If probability ATC computing velocity is too slow, then the counting yield of AQTC can be made to be difficult to be protected, also just be difficult in engineering be used; If the precision that probability ATC calculates is inadequate, then can make the follow-up AQTC that calculates and actual value deviation excessive, do not have the directive function to both parties, cause waste or the shortage of electric power resource.

Summary of the invention

For the problems referred to above, the object of this invention is to provide a kind of Calculation of Available Transfer Capability method based on Probabilistic Load Flow taking into account accuracy and runtime.

For achieving the above object, the present invention takes following technical scheme: a kind of Calculation of Available Transfer Capability method based on Probabilistic Load Flow, it comprises the following steps: 1) to needing the electric system calculating AQTC, several typical way are chosen within the cycle, this typical way comprises typical way 1, typical way 2,, typical way n, and set the duration of each typical way within the cycle; 2) successively using the method for operation of each typical way as this electric system, calculate the probability ATC of this electric system under each method of operation to expect, it comprises the following steps: 2-1) read in the data of electric system under a certain method of operation that will calculate, this electric power system data comprises the parameters of each transmission of electricity element; And set this electric system accuracy requirement required under this method of operation; 2-2) respectively to transmit electricity according to gained the parameter of element, calculate the determinacy ATC of this electric system, be designated as ATC _c; 2-3) make the ATC of gained _cfor power is flowed out in feeder section injecting power, powered region, calculate the Probabilistic Load Flow distribution of now this electric system, it comprises the power distribution of transmission line of electricity and the voltage's distribiuting of transmission of electricity bus; 2-4) distribute according to the Probabilistic Load Flow of this electric system, calculate each transmission of electricity element to the factor of influence of system ATC, and from big to small transmission of electricity element is sorted according to factor of influence; 2-5) choose the initial transmission of electricity element of the sets of elements that the maximum transmission of electricity element of factor of influence is formed for interpolation transmission of electricity element as this electric system, calculate its transmission of electricity element ATC using the initial distribution curve of the probability distribution curve of the transmission of electricity element ATC of gained as this Probabilistic ATC, using the initial expectation of the expectation of initial distribution curve as this Probabilistic ATC; 2-6) according to factor of influence ranking results from big to small, add transmission of electricity element successively in sets of elements; 2-7) judge that whether the transmission of electricity element for adding is separate with each transmission of electricity element added; If independent, then carry out next step; If not independent, then reject, turn back to step 2-6) add next transmission of electricity element; 2-8) calculate institute and add the probability ATC of element of transmitting electricity, its distribution curve and this electric system original probability ATC distribution curve are carried out matching, obtains the probability ATC distribution curve that this electric system is new, and calculate the expectation of new probability ATC distribution curve; If 2-9) difference of the new expectation of this electric system gained and the former expectation of last gained meets the accuracy requirement preset, then using new probability ATC distribution curve as the final distribution curve of this electric system; If do not meet, then return step 2-6) continue to add new transmission of electricity element, until meet the accuracy requirement preset; 3) the probability ATC under each typical way is expected that correspondence was multiplied with the duration of each typical way, and the AQTC obtained in the cycle that each product of gained is sued for peace.

Described step 2) 2-4) comprise following content: transmission of electricity element factor of influence μ on system probability ATC affect as follows: establish transmission line of electricity i to the factor of influence μ of system probability ATC _ifor: wherein, P _imaxfor the peak power of the permission of transmission line of electricity i; P _ifor the probability power of transmission line of electricity i; If bus j is to the factor of influence μ of system probability ATC _jfor: wherein, V _jminfor the lower limit of busbar voltage; V _jmaxfor the upper limit of busbar voltage; V _jfor the voltage of bus j; By the size of factor of influence μ value, can sort to the influence degree of each transmission of electricity element to electric system, it represents μ _iand μ _jbe referred to as factor of influence μ, μ value is larger, and influence degree is larger, and vice versa.

Described step 2) 2-5) comprise following content: transmission of electricity element ATC, comprise transmission line of electricity available transmission capacity LATC and transmission of electricity bus available transmission capacity BATC; 1. the available transmission capacity LATC of transmission line of electricity: set with any transmission line of electricity i as bottleneck factor, it is the available transmission capacity LATC of this transmission line of electricity i that electric system can be used further to the transmission capacity that business uses _i; If Δ LATC _ifor under the system state of the determination of known all parameters, during with transmission line of electricity i for bottleneck factor, the power that feed, powered two regions also can increase or reduce; If P _i, Δ LATC _iboth relation with increases are positive correlation, then have: ${\mathrm{LATC}}_i={\mathrm{ATC}}_c+\mathrm{\&Delta;}{\mathrm{LATC}}_i={\mathrm{ATC}}_c+\frac{P_{i\max }-P_i}{S_{\mathrm{Ai}}-S_{\mathrm{Bi}}};$ Wherein, P _imaxfor the peak power of the permission of transmission line of electricity i; P _ifor the probability power of transmission line of electricity i; S _aifor feeder section power increases the sensitivity to transmission line of electricity i power; S _bifor powered area power increases the sensitivity to transmission line of electricity i power; If P _i, Δ LATC _iboth relation with increases are negative correlation, then think LATC now _ifor infinite, do not consider that this transmission line of electricity i is on the impact of probability results; 2. transmit electricity the available transmission capacity BATC of bus: set with any one bus j as bottleneck factor, and electric system can be used further to the available transmission capacity BATC that transmission capacity that business uses is bus j _j; If Δ BATC _jfor under the system state of the determination of known all parameters, during with bus j for bottleneck factor, the power that feed, powered two regions also can increase or reduce; If V _j, Δ BATC _jboth relation with increases are positive correlation, then have: work as V _j< V _jmintime: ; Work as V _j> V _jmintime: ${\mathrm{BATC}}_j={\mathrm{ATC}}_c+\mathrm{\&Delta;}{\mathrm{BATC}}_j={\mathrm{ATC}}_c+\frac{V_{j\max }-V_j}{S_{\mathrm{Aj}}-S_{\mathrm{Bj}}};$ Wherein, V _jminfor the lower limit of busbar voltage; V _jmaxfor the upper limit of busbar voltage; S _ajfor feeder section power increases the voltage sensitivity to bus j; S _bjfor powered area power increases the voltage sensitivity to bus j; S during positive correlation _aj-S _bj> 0; If V _j, Δ BATC _jboth relation with increases are negative correlation, then have: work as V _j> V _jmaxtime: ; Work as V _j< V _jmaxtime: ${\mathrm{BATC}}_j={\mathrm{ATC}}_c+\mathrm{\&Delta;}{\mathrm{BATC}}_j={\mathrm{ATC}}_c+\frac{V_j-V_{j\min }}{S_{\mathrm{Aj}}-S_{\mathrm{Bj}}}.$

Described step 2) 2-7) in the relevant condition of any two transmission lines of electricity as follows: if two transmission lines of electricity can meet following three requirements numerically simultaneously, then these two transmission lines of electricity are relevant: dominate degree of correlation β _dbe greater than maximum relation degree S _max75%: ; Total relevance β is greater than 75% of the leading degree of correlation: jack per line number λ is greater than 75% of total node number N or is less than 25% of total node number N: or

The present invention is owing to taking above technical scheme, it has the following advantages: 1, the present invention utilizes the probability ATC of probabilistic load flow system, compare simulation and greatly reduce calculated amount, thus improve the computing velocity of system probability ATC, and then improve the computing velocity of AQTC.2, transmission of electricity element ATC and the concept to system ATC factor of influence thereof are proposed, in electric system, transmission of electricity element is added successively according to factor of influence order from big to small, in the middle of the probability ATC result impact of more transmission of electricity elements being considered system, reduce the deviation expected with system actual probabilities ATC step by step, and then the probability ATC computational accuracy met required by system, meet the computational accuracy of AQTC simultaneously.In view of above reason, the present invention can be widely used in probability available power transport capacity and calculate and probability Calculation of Available Transfer Capability field.

Accompanying drawing explanation

Fig. 1 is that typical way chooses schematic diagram

Fig. 2 is the schematic flow sheet that in the present invention, probability ATC calculates

Fig. 3 is the probability distribution schematic diagram of transmission line of electricity i power

Fig. 4 is the power P of transmission line of electricity i _iwith Δ LATC _ibetween qualitative relationships schematic diagram

Fig. 5 is the probability distribution schematic diagram of transmission of electricity bus j voltage

Fig. 6 is the voltage V of transmission of electricity bus j _jwith Δ BATC _jbetween qualitative relationships schematic diagram

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in detail.

1) as shown in Figure 1, first needs are calculated to the electric system of AQTC (Available Quantity Transfer Capability, available power transport capacity), several typical way are chosen within the cycle, i.e. typical way 1, typical way 2 ..., typical way n.Set the duration of each typical way within the cycle, selection principle is as follows: within the minor cycle that changes of operating modes is little, choose a typical way representatively, once larger change occurs the method for operation, just again chooses typical way.In practical power systems, staff has found out comparatively ripe typical way choosing method according to the experience run for many years, can directly apply into.

2) successively using the method for operation of each typical way as this electric system, and calculate the expectation of the probability ATC of this electric system under each method of operation, it comprises the following steps:

It should be noted that, the step that probability ATC expectation is asked in this electric system under different running method is consistent, and therefore no longer repeat specification is only representatively described with the process of asking for of this kind of method of operation lower probability ATC.

2-1) as shown in Figure 2, read in the data of electric system under this method of operation that will calculate, this electric power system data comprises the parameters of the transmission of electricity such as generator, transmission line of electricity, transformer, the reactive power compensator element commonly used this area, to calculate determinacy ATC and the Probabilistic Load Flow of this electric system according to these existing parameters.Utilize the result of Probabilistic Load Flow can obtain the probability ATC of transmission of electricity element, be the available transmission capacity of transmission of electricity element, it comprises the available transmission capacity LATC (Line Available Transfer Capability) of transmission line of electricity and the available transmission capacity BATC (Bus Available Transfer Capability) of transmission of electricity bus.The transmission of electricity element that refering in particular in the present invention affects Probabilistic ATC size is transmission line of electricity and generator, and the ATC of transmission line of electricity is LATC, and the ATC of generator is BATC.

2-2) respectively transmit electricity according to gained the parameter of element, the ATC algorithm based on continuous tide utilizing this area to commonly use calculates the determinacy ATC of electric system, is designated as ATC _c;

2-3) make the ATC of gained _cfor power is flowed out in feeder section injecting power, powered region, adopt the Probabilistic Load Flow algorithm in conjunction with cumulant and Gram-Charlier series expansion that this area is commonly used, calculate the Probabilistic Load Flow distribution of now this electric system, it comprises the power distribution of transmission line of electricity and the voltage's distribiuting of transmission of electricity bus;

2-4) distribute according to the Probabilistic Load Flow of this electric system, calculate each transmission of electricity element to the factor of influence of system ATC, and from big to small transmission of electricity element is sorted according to factor of influence;

System probability ATC is limited by the transmission of electricity element of out-of-limit (having exceeded operational limit) at first, so operate in from the transmission of electricity element close to ultimate limit state, may be larger on the impact of system probability ATC, therefore propose transmission of electricity element factor of influence μ in order to respectively transmit electricity element to the size of system probability ATC influence degree.

If transmission line of electricity i is to the factor of influence μ of system probability ATC _ifor:

${\mathrm{\&mu;}}_i=1-{\&Integral;}_0^{P_{i\max }}{P}_i\left(x\right)\mathrm{dx}---\left(1\right)$

If bus j is to the factor of influence μ of system probability ATC _jfor:

${\mathrm{\&mu;}}_j=1-{\&Integral;}_{V_{i\min }}^{V_{i\max }}{V}_j\left(x\right)\mathrm{dx}---\left(2\right)$

By factor of influence μ (μ _iand μ _jbe referred to as factor of influence μ) size of value, can sort to the influence degree of each transmission of electricity element to electric system: μ value is larger, and influence degree is larger, and vice versa.So, when interpolation transmission of electricity element carries out probability simulation iteration, the less transmission of electricity element of influence degree can just be ignored when meeting precision.For the real system that, bottleneck transmission of electricity element comparatively large for system scale is comparatively concentrated, greatly reduce calculated amount.

2-5) choose the initial transmission of electricity element of the sets of elements that the maximum transmission of electricity element of factor of influence is formed for interpolation transmission of electricity element as this electric system, calculate its transmission of electricity element ATC using the initial distribution curve of its probability distribution curve as this Probabilistic ATC, using the initial expectation of the expectation of initial distribution curve as this Probabilistic ATC;

1. the available transmission capacity LATC of transmission line of electricity

If with any transmission line of electricity i for bottleneck factor, it is the available transmission capacity LATC of this transmission line of electricity i that electric system can be used further to the transmission capacity that business uses _i.

As shown in Figure 3, Figure 4, if Δ LATC _ithe power that under the system state of the determination of known all parameters, during with transmission line of electricity i for bottleneck factor, feed, powered two regions also can increase (or minimizing), wherein, Δ LATC _i>0 illustrates under this system state, and transmission line of electricity i does not also reach itself operational limit; Δ LATC _i=0 illustrates under this system state, and transmission line of electricity i just reaches operational limit; Δ LATC _i<0 illustrates under this system state, and transmission line of electricity i has exceeded operational limit already.If P _ifor the probability power of transmission line of electricity i.

If along with Δ LATC _iincrease, power (absolute value) P of transmission line of electricity i _ialso increase, i.e. Δ LATC _iwith P _irelation with increase be positive correlation, then both sides relation is as follows:

$\begin{array}{cc}\mathrm{\&Delta;}{\mathrm{LATC}}_i=\frac{P_{i\max }-P_i}{S_{\mathrm{Ai}}-S_{\mathrm{Bi}}}& S_{\mathrm{Ai}}-S_{\mathrm{Bi}}>0---\left(3\right)\end{array}$

Wherein, P _imaxfor the maximum transmission power that transmission line of electricity i allows; S _aifor feeder section power increases the sensitivity to transmission line of electricity i power; S _bifor powered area power increases the sensitivity to transmission line of electricity i power, owing to being load growth, so band negative sign; S _ai-S _bi> 0 is equivalent to Δ LATC _iwith P _ibetween relation with increase be positive correlation.

If along with Δ LATC _iincrease, the power (absolute value) of transmission line of electricity i reduces, i.e. Δ LATC _iwith P _irelation with increase be negative correlation (S _ai-S _bi< 0), so can think Δ LATC now _ifor just infinite.Under normal circumstances, if along with Δ LATC _iincrease, the power (absolute value) of transmission line of electricity i reduces, and is so constantly increasing Δ LATC _iprocess in, transmission line of electricity i does not reach oneself the limit forever, because the limit of circuit is an inaccessiable maximal value, does not have lower limit, so can think Δ LATC _ifor just infinite, in other words when negative correlation, do not consider that this transmission line of electricity i is on the impact of probability results.

Formula (4) is utilized to calculate the available transmission capacity LATC of transmission line of electricity i _i:

${\mathrm{LATC}}_i={\mathrm{ATC}}_c+\mathrm{\&Delta;}{\mathrm{LATC}}_i={\mathrm{ATC}}_c+\frac{P_{i\max }-P_i}{S_{\mathrm{Ai}}-S_{\mathrm{Bi}}}---\left(4\right)$

2. transmit electricity the available transmission capacity BATC of bus

If with any one bus j for bottleneck factor, electric system can be used further to transmission capacity that business the uses available transmission capacity BATC that is bus j _j.

As shown in Figure 5, Figure 6, if Δ BATC _jthe power that under the system state of the determination of known all parameters, during with bus j for bottleneck factor, feed, powered two regions also can increase (or minimizing), wherein, Δ BATC _j>0 illustrates under this system state, and bus j does not also reach operational limit; Δ BATC _j=0 illustrates under this system state, and bus j just reaches operational limit; Δ BATC _j<0 illustrates under this system state, and bus j has exceeded operational limit already.

If V _j, Δ BATC _jboth relation with increases are positive correlation, then have:

Work as V _j< V _jmintime: BATC _j=0 (5)

Work as V _j> V _jmintime: ${\mathrm{BATC}}_j={\mathrm{ATC}}_c+\frac{V_{j\max }-V_j}{S_{\mathrm{Aj}}-S_{\mathrm{Bj}}}---\left(6\right)$

Wherein, V _jfor the voltage of bus j; V _jminfor the lower limit of the voltage of bus j; V _jmaxfor the upper limit of the voltage of bus j; S _ajfor feeder section power increases the voltage sensitivity to bus j; S _bjfor powered area power increases the voltage sensitivity to bus j; S during positive correlation _aj-S _bj> 0.

If V _j, Δ BATC _jboth relation with increases are negative correlation, then have:

Work as V _j> V _jmaxtime: BATC _j=0 (7)

Work as V _j< V _jmaxtime: ${\mathrm{BATC}}_j={\mathrm{ATC}}_c+\frac{V_j-V_{j\min }}{S_{\mathrm{Aj}}-S_{\mathrm{Bj}}}---\left(8\right)$

It should be noted that, due to the power P of transmission line of electricity i _i, transmission of electricity bus j voltage V _jfor probable value, so the available transmission capacity LATC of transmission line of electricity i _iwith the available transmission capacity BATC of transmission of electricity bus j _jbe probabilistic ATC.

2-6) according to factor of influence ranking results from big to small, add transmission of electricity element successively in sets of elements, owing to multiple transmission of electricity element can be considered in the middle of probability results successively according to factor of influence size, so can think, add transmission of electricity element more, from exact value more close to, precision is higher, while meeting computing velocity, accomplish the control in precision;

2-7) judge that whether the transmission of electricity element for adding is separate with each transmission of electricity element added; If independent, then carry out next step; If relevant (not independent), then reject, turn back to step 2-6) add next transmission of electricity element, judge that independently process is as follows:

If be bus for the transmission of electricity element added, because be independently between bus and transmission line of electricity, then directly add and carry out next step, not needing to judge the mutual independence with the transmission of electricity element added; If the transmission of electricity element added is transmission line of electricity, then carries out the calculating of the degree of correlation with the transmission line of electricity that added in sets of elements, judge mutual independence with this, do not need to carry out independence judgement with the transmission of electricity bus that added in sets of elements.

Correlativity determination methods between transmission line of electricity is as follows:

If any two transmission lines of electricity are m-n, p-q, define the total relevance (Line Relevancy, LR) of these two transmission lines of electricity for they are to the sum of products of each node injection sensitivity, then the total relevance β between any two transmission lines of electricity:

$\mathrm{\&beta;}=\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}{S}_{m-n,j}\&times;S_{p-q,j}---\left(9\right)$

Wherein, β is the total relevance between transmission line of electricity m-n, p-q; N is calculated electric system interior joint number; S _{m-n, i}power for calculated electric system median generatrix j injects the sensitivity to transmission line of electricity m-n; S _{p-q, i}power for calculated electric system median generatrix j injects the sensitivity to transmission line of electricity p-q.

In view of generally, transmission line of electricity power has the greatest impact by transmission line of electricity two-end-point injecting power, be embodied in the middle of the l-w sensitivity matrix between transmission line of electricity power l and node injecting power w, show as end points injecting power to the sensitivity number of transmission line of electricity at all node powers to maximum among its sensitivity.

So the injecting power sensitivity of transmission line of electricity end points is considered separately, the sensitivity sum of products of definition transmission line of electricity end points to two transmission lines of electricity takes the degree of correlation (Dominant Relevancy as the leading factor, DR), if two transmission lines of electricity have same endpoints, then coincidence node is only calculated once:

${\mathrm{\&beta;}}_D=\underset{j=m,n,p,q}{\mathrm{\&Sigma;}}{S}_{m-n,j}\&times;S_{p-q,j}---\left(10\right)$

Wherein, β _dfor the leading degree of correlation of transmission line of electricity m-n and transmission line of electricity p-q.

Defining the sensitivity sum of products of all the other nodes to two transmission lines of electricity is the non-dominant degree of correlation (Non-Dominant Relevancy, NDR):

${\mathrm{\&beta;}}_N=\underset{j\&NotEqual;m,n,p,q}{\mathrm{\&Sigma;}}{S}_{m-n,j}\&times;S_{p-q,j}---\left(11\right)$

Wherein, β _nfor the non-dominant degree of correlation of transmission line of electricity m-n and transmission line of electricity p-q.

Add up the jack per line number λ of two transmission lines of electricity to each node sensitivity, and calculate the maximal value of sensitivity product, i.e. maximum relation degree S _max:

S _max＝max{S _m-n,j×S _p-q,j} (12)

The leading degree of correlation embodies each Pilot bus (transmission line of electricity end points) random fluctuation affects sum to two transmission line of electricity power.If two transmission lines of electricity are correlated with, then the product of each Pilot bus sensitivity keeps jack per line (or contrary sign nodal values is very little) substantially, and the leading degree of correlation is larger.

Total relevance embodies each node random fluctuation to two transmission line of electricity power influences sums.If two transmission lines of electricity are correlated with, then the Pilot bus degree of correlation can be comparatively large, the non-dominant degree of correlation should with leading degree of correlation jack per line, or with its contrary sign but numerical value is very little, the total relevance that both add up can be larger.

Jack per line number embodies each node random fluctuation affects direction to two transmission line of electricity power.If two transmission line of electricity positive correlations, then jack per line nodes will much larger than contrary sign nodes; If two transmission line of electricity negative correlation, then jack per line nodes will much smaller than contrary sign nodes.

Three requirements numerically below if two transmission lines of electricity can meet simultaneously, then these two transmission lines of electricity are relative to each other, namely independent: leading degree of correlation β _dbe greater than maximum relation degree S _max75%: total relevance β is greater than leading degree of correlation β _d75%: jack per line number λ is greater than 75% of total node number N or is less than 25% of total node number N: or

2-8) calculate institute and add the probability ATC of element of transmitting electricity, its distribution curve and this electric system original probability ATC distribution curve are carried out matching, obtain the probability ATC distribution curve that this electric system is new, and calculate the expectation of new probability ATC distribution curve, fit procedure is as follows:

P _AB(x)＝P _A(x)×P _B(B≥x)+P _A(A≥x)×P _B(x)-P _A(x)×P _B(x) (13)

Wherein, AB is the system be made up of any two transmission of electricity elements A, B; P _aBfor the distribution of the probability ATC of AB system; P _afor the probability ATC of transmission of electricity element A distributes; P _bfor the probability ATC of transmission of electricity element B distributes; X ∈ (0 ,+∞).

Introduce cumulative function $F_A\left(x\right)=\underset{-\&infin;}{\overset{x}{\&Integral;}}{P}_A\left(x\right)\mathrm{dx},F_B\left(x\right)=\underset{-\&infin;}{\overset{x}{\&Integral;}}{P}_B\left(x\right)\mathrm{dx},$ Then have:

P _AB(x)＝P _A(x)×(1-F _B(x))+(1-F _A(x))×P _B(x)+P _A(x)×P _B(x) (14)

If 2-9) difference of the new expectation of this electric system gained and the former expectation of last gained meets the accuracy requirement preset, then using new probability ATC distribution curve as the final distribution curve of this electric system; If do not meet, then return step 2-6) continue to add new transmission of electricity element, until meet the accuracy requirement preset.

3) the probability ATC under each typical way is expected that correspondence was multiplied with the duration of each typical way, and the AQTC obtained in the cycle that each product of gained is sued for peace.

The above; be only the present invention's preferably embodiment; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses; be equal to according to technical scheme of the present invention and inventive concept thereof and replace or change, all should be encompassed within protection scope of the present invention.

Claims (5)

1., based on a Calculation of Available Transfer Capability method for Probabilistic Load Flow, it comprises the following steps:

1) to needing the electric system calculating AQTC, within the cycle, choose several typical way, this typical way comprises typical way 1, typical way 2 ..., typical way n, and set the duration of each typical way within the cycle;

2) successively using the method for operation of each typical way as this electric system, calculate the probability ATC of this electric system under each method of operation and expect, it comprises the following steps:

2-1) read in the data of electric system under a certain method of operation that will calculate, this electric power system data comprises the parameters of each transmission of electricity element; And set this electric system accuracy requirement required under this method of operation;

2-2) respectively to transmit electricity according to gained the parameter of element, calculate the determinacy ATC of this electric system, be designated as ATC _c;

2-3) make the ATC of gained _cfor power is flowed out in feeder section injecting power, powered region, calculate the Probabilistic Load Flow distribution of now this electric system, it comprises the power distribution of transmission line of electricity and the voltage's distribiuting of transmission of electricity bus;

2-4) distribute according to the Probabilistic Load Flow of this electric system, calculate each transmission of electricity element to the factor of influence of system ATC, and from big to small transmission of electricity element is sorted according to factor of influence;

2-5) choose the initial transmission of electricity element of the sets of elements that the maximum transmission of electricity element of factor of influence is formed for interpolation transmission of electricity element as this electric system, calculate its transmission of electricity element ATC using the initial distribution curve of the probability distribution curve of the transmission of electricity element ATC of gained as this Probabilistic ATC, using the initial expectation of the expectation of initial distribution curve as this Probabilistic ATC;

2-6) according to factor of influence ranking results from big to small, add transmission of electricity element successively in sets of elements;

2-7) judge that whether the transmission of electricity element for adding is separate with each transmission of electricity element added; If independent, then carry out next step; If not independent, then reject, turn back to step 2-6) add next transmission of electricity element;

2-8) calculate institute and add the probability ATC of element of transmitting electricity, its distribution curve and this electric system original probability ATC distribution curve are carried out matching, obtains the probability ATC distribution curve that this electric system is new, and calculate the expectation of new probability ATC distribution curve;

If 2-9) difference of the new expectation of this electric system gained and the former expectation of last gained meets the accuracy requirement preset, then using new probability ATC distribution curve as the final distribution curve of this electric system; If do not meet, then return step 2-6) continue to add new transmission of electricity element, until meet the accuracy requirement preset;

3) the probability ATC under each typical way is expected that correspondence was multiplied with the duration of each typical way, and the AQTC obtained in the cycle that each product of gained is sued for peace.

2. a kind of Calculation of Available Transfer Capability method based on Probabilistic Load Flow as claimed in claim 1, is characterized in that: described step 2) 2-4) comprise following content:

The factor of influence μ of transmission of electricity element affects as follows on system probability ATC:

If transmission line of electricity i is to the factor of influence μ of system probability ATC _ifor:

${\mathrm{\&mu;}}_i=1-{\&Integral;}_0^{P_{i\max }}{P}_i\left(x\right)\mathrm{dx}$

Wherein, P _imaxfor the peak power of the permission of transmission line of electricity i; P _ifor the probability power of transmission line of electricity i;

If bus is to the factor of influence μ of system probability ATC _jfor:

${\mathrm{\&mu;}}_j=1-{\&Integral;}_{V_{i\min }}^{V_{i\max }}{V}_j\left(x\right)\mathrm{dx}$

Wherein, V _jminfor the lower limit of busbar voltage; V _jmaxfor the upper limit of busbar voltage; V _jfor the voltage of bus j;

By the size of factor of influence μ value, can sort to the influence degree of each transmission of electricity element to electric system, it represents μ _iand μ _jbe referred to as factor of influence μ, μ value is larger, and influence degree is larger, and vice versa.

3. a kind of Calculation of Available Transfer Capability method based on Probabilistic Load Flow as claimed in claim 1, is characterized in that: described step 2) 2-5) comprise following content:

The ATC of transmission of electricity element, comprises the available transmission capacity LATC of transmission line of electricity and the available transmission capacity BATC of transmission of electricity bus;

1. the available transmission capacity LATC of transmission line of electricity

If with any transmission line of electricity i for bottleneck factor, it is the available transmission capacity LATC of this transmission line of electricity i that electric system can be used further to the transmission capacity that business uses _i; If Δ LATC _ifor under the system state of the determination of known all parameters, during with transmission line of electricity i for bottleneck factor, the power that feed, powered two regions also can increase or reduce;

If P _i, Δ LATC _iboth relation with increases are positive correlation, then have:

${\mathrm{LATC}}_i={\mathrm{ATC}}_c+\mathrm{\&Delta;}{\mathrm{LATC}}_i={\mathrm{ATC}}_c+\frac{P_{i\max }-P_i}{S_{\mathrm{Ai}}-S_{\mathrm{Bi}}}$

Wherein, P _imaxfor the peak power of the permission of transmission line of electricity i; P _ifor the probability power of transmission line of electricity i; S _aifor feeder section power increases the sensitivity to transmission line of electricity i power; S _bifor powered area power increases the sensitivity to transmission line of electricity i power;

If P _i, Δ LATC _iboth relation with increases are negative correlation, then think LATC now _ifor infinite, do not consider that this transmission line of electricity i is on the impact of probability results;

2. transmit electricity the available transmission capacity BATC of bus

If with any one bus j for bottleneck factor, electric system can be used further to transmission capacity that business the uses available transmission capacity BATC that is bus j _j; If Δ BATC _jfor under the system state of the determination of known all parameters, during with bus j for bottleneck factor, the power that feed, powered two regions also can increase or reduce;

If V _j, Δ BATC _jboth relation with increases are positive correlation, then have:

Work as V _j< V _jmintime: BATC _j=0

Work as V _j> V _jmintime: ${\mathrm{BATC}}_j={\mathrm{ATC}}_c+\mathrm{\&Delta;}{\mathrm{BATC}}_j={\mathrm{ATC}}_c+\frac{V_{j\max }-V_j}{S_{\mathrm{Aj}}-S_{\mathrm{Bj}}}$

Wherein, V _jminfor the lower limit of busbar voltage; V _jmaxfor the upper limit of busbar voltage; S _ajfor feeder section power increases the voltage sensitivity to bus j; S _bjfor powered area power increases the voltage sensitivity to bus j; S during positive correlation _aj-S _bj> 0;

If V _j, Δ BATC _jboth relation with increases are negative correlation, then have:

Work as V _j> V _jmaxtime: BATC _j=0

Work as V _j< V _jmaxtime: ${\mathrm{BATC}}_j={\mathrm{ATC}}_c+\mathrm{\&Delta;}{\mathrm{BATC}}_j={\mathrm{ATC}}_c+\frac{V_j-V_{j\min }}{S_{\mathrm{Aj}}-S_{\mathrm{Bj}}}.$

4. a kind of Calculation of Available Transfer Capability method based on Probabilistic Load Flow as claimed in claim 2, is characterized in that: described step 2) 2-5) comprise following content:

The ATC of transmission of electricity element, comprises the available transmission capacity LATC of transmission line of electricity and the available transmission capacity BATC of transmission of electricity bus;

1. the available transmission capacity LATC of transmission line of electricity

If with any transmission line of electricity i for bottleneck factor, it is the available transmission capacity LATC of this transmission line of electricity i that electric system can be used further to the transmission capacity that business uses _i; If Δ LATC _ifor under the system state of the determination of known all parameters, during with transmission line of electricity i for bottleneck factor, the power that feed, powered two regions also can increase or reduce;

If P _i, Δ LATC _iboth relation with increases are positive correlation, then have:

${\mathrm{LATC}}_i={\mathrm{ATC}}_c+\mathrm{\&Delta;}{\mathrm{LATC}}_i={\mathrm{ATC}}_c+\frac{P_{i\max }-P_i}{S_{\mathrm{Ai}}-S_{\mathrm{Bi}}}$

Wherein, P _imaxfor the peak power of the permission of transmission line of electricity i; P _ifor the probability power of transmission line of electricity i; S _aifor feeder section power increases the sensitivity to transmission line of electricity i power; S _bifor powered area power increases the sensitivity to transmission line of electricity i power;

If P _i, Δ LATC _iboth relation with increases are negative correlation, then think LATC now _ifor infinite, do not consider that this transmission line of electricity i is on the impact of probability results;

2. transmit electricity the available transmission capacity BATC of bus

If with any one bus j for bottleneck factor, electric system can be used further to transmission capacity that business the uses available transmission capacity BATC that is bus j _j; If Δ BATC _jfor under the system state of the determination of known all parameters, during with bus j for bottleneck factor, the power that feed, powered two regions also can increase or reduce;

If V _j, Δ BATC _jboth relation with increases are positive correlation, then have:

Work as V _j< V _jmintime: BATC _j=0

Work as V _j> V _jmintime: ${\mathrm{BATC}}_j={\mathrm{ATC}}_c+\mathrm{\&Delta;}{\mathrm{BATC}}_j={\mathrm{ATC}}_c+\frac{V_{j\max }-V_j}{S_{\mathrm{Aj}}-S_{\mathrm{Bj}}}$

Wherein, V _jminfor the lower limit of busbar voltage; V _jmaxfor the upper limit of busbar voltage; S _ajfor feeder section power increases the voltage sensitivity to bus j; S _bjfor powered area power increases the voltage sensitivity to bus j; S during positive correlation _aj-S _bj> 0;

If V _j, Δ BATC _jboth relation with increases are negative correlation, then have:

Work as V _j> V _jmaxtime: BATC _j=0

Work as V _j< V _jmaxtime: ${\mathrm{BATC}}_j={\mathrm{ATC}}_c+\mathrm{\&Delta;}{\mathrm{BATC}}_j={\mathrm{ATC}}_c+\frac{V_j-V_{j\min }}{S_{\mathrm{Aj}}-S_{\mathrm{Bj}}}.$

5. a kind of Calculation of Available Transfer Capability method based on Probabilistic Load Flow as claimed in claim 1 or 2 or 3 or 4, is characterized in that: described step 2) 2-7) in the relevant condition of any two transmission lines of electricity as follows:

Three requirements numerically below if two transmission lines of electricity can meet simultaneously, then these two transmission lines of electricity are relevant: leading degree of correlation β _dbe greater than maximum relation degree S _max75%: total relevance β is greater than 75% of the leading degree of correlation: jack per line number λ is greater than 75% of total node number N or is less than 25% of total node number N: $\mathrm{\&lambda;}>\frac{3}{4}N$ Or $\mathrm{\&lambda;}<\frac{1}{4}N.$