CN101752870A - Method for analysis of available power supply capacity of medium voltage distribution network - Google Patents

Abstract

The invention, belonging to the field of calculating index of distribution network, the power supply capacity, in planning distribution system, relates to a method for the analysis of available power supply capacity of a medium voltage distribution network, comprising the steps: establishing an available power supply capacity mode; analyzing the communication relationship between main transformers in research area to form a main transformer communication relationship matrix Llink; according to the differences of in-station communication and inter-station communication, partitioning the matrix Llink and correcting the main transformer communication relationship matrix Llink; defining the elements of a capacity matrix R to represent main transformer capacity of corresponding communication center and correcting matrix R; calculating the available power supply capacity of the system; positioning weak points; and acquiring critical capacity. In the method for the analysis of available power supply capacity of the medium voltage distribution network according to the invention, the available power supply capacity calculation mode and the calculation analysis method are put forward, and on the basis of the available power supply capacity, the analysis method is put forward, in which the weak points in grid, which restrict the available power supply capacity, are rapidly positioned by channel-transferring bottleneck matrix, and the minimal element capacity required by communication line is obtained via the critical capacity.

Description

The medium voltage distribution network method for analysis of available power supply capacity

Technical field

The invention belongs to power distribution network index power supply capacity calculating field in the distribution system planning, relate to a kind of medium voltage distribution network method for analysis of available power supply capacity.

Background technology

The city power distribution system is important foundation facility and the necessary energy supply system that urban modernization is built.For a long time, the electrical network in the many cities of China exists problems such as power supply capacity deficiency, the network transitions ability is uncertain, the grid equipment utilance is not high, load is unbalanced, loss is big.Along with the continuous increase of electricity needs, electrical network also needs continuous expansion.In order to adapt to the constantly soaring of rapid economy development and power load, the development of distribution construction and major network is adapted, avoid overlapping construction and invest, need carry out the optimization planning of distribution system, to eliminate safe hidden trouble according to part throttle characteristics and increasing law thereof, improve operational efficiency, improve the power supply capacity of distribution system, under the prerequisite that guarantees power grid security, reliability service, meet consumers' demand, for national security, economic development and social stability provide reliable guarantee.

The main function of distribution system is that the electric energy that the transmission system transmission comes is distributed to power consumer efficiently, reliably, and this distribution capability also can be referred to as distribution ability or power supply capacity, the present invention proposes these new ideas of available power supply capacity.The operation of distribution system has the rule that himself need satisfy, if run counter to above-mentioned rule, for example exceeds power supply capacity operation, will cause short circuit, open circuit, damages accident such as power distribution equipment, even lead to grave consequences.In addition, for the redundancy that guarantees that distribution system is certain, it still can be powered under fault condition, " urban power network planning and designing guide rule " also stipulated the safety criterion N-1 criterion that distribution system need satisfy.

Therefore, move reliably in order to make power distribution system secure, need be on the basis of distribution network, in conjunction with the operation constraint, power supply capacity is carried out reasonable assessment,, avoid occurring exceeding the dangerous situation of power supply capacity operation in the operation of power networks process, to carry out corresponding control.The assessment of the power supply capacity of distribution system has become become more meticulous key one ring of assessment and planning of current urban distribution network, for optimizing network configuration, the planning of instructing urban distribution network and operation, has huge economic benefit and social benefit.

The research of related city medium voltage distribution network power supply capacity, adopted traditionally the exploratory method of approaching and the posteriority formula of constraints being satisfied of desired value, check the ability of this load level of offered load by distribution power system load flow calculation, with the power supply capacity of definite urban distribution network, or directly calculate the power distribution network power supply capacity.Tradition power supply capacity development of method for calculating has been passed through three phases: one, with the power transformation capacity assessment distribution system power supply capacity stage, as the capacity-load ratio method.The power transformation capacity of this stage with transformer station is main foundation, estimated mains supply ability size from macroscopic view, and these class methods are calculated simple, but do not consider the effect of distribution network to power supply capacity, and computational methods lose contact with reality; Two, take into account the distribution system power supply capacity research trial stage of network power supply ability, as peak load method of multiplicity, network max-flow method, load-bearing capacity method.When this stage method is examined or check transformer station's power transformation capacity, also the foundation of feeder line capacity as the calculating of mains supply ability, it is actual more to fit, the thought blank that the network transitions power supply capacity is calculated has been proposed, but it is irrational only loading estimation network to shift power supply capacity with feeder line, the network practical structures that it is ignored is to the influence of power supply capacity, and result of calculation and physical presence are than big-difference; Three, based on N-1 safety criterion and the interconnected power supply capacity calculation stages of transformer station's topology, as based on the interconnected method of main transformer, linear programming technique, the wherein the most representative interconnected power supply capacity computational methods of main transformer that are based on are seen application for a patent for invention " the distribution system power supply capacity appraisal procedure (number of patent application 200810151314.6) of a kind of taking into account " N-1 " criterion ".The power distribution network power supply capacity computation model that this stage method proposes, can calculate in the distribution website under the N-1 condition, the computational methods of network transitions power supply capacity, these class computational methods are calculated easy, practicality is good, but assumed conditions is too desirable, and is big as the transfering channel infinite capacity.Error calculated is bigger, need be according to the actual service conditions of network to the further precision of model.

Available transfer capacity of transmission network (ATC) and maximum transmitted ability (TTC) are the important indicators that the reflection transmission system can be used for the residual capacity of transferring electric power.Two interregional TTC are meant and can satisfy the safe operation requirement of system under normal and particular incident situation in the electric power system, each zone by interconnected electric power transmission network the electric power total amount of energy reliable transmission; ATC considers transmission of electricity agreement and nargin constraint down, available transmission capacity in the electric power transmission network.

Summary of the invention

In traditional power supply capacity is calculated, the calculation assumption condition of power distribution network power supply capacity is very good, do not consider of the influence of factors such as the network operation to the power supply capacity index, the objective of the invention is, on above-mentioned patent application 200810151314.6 bases, a kind of method for analysis of available power supply capacity is proposed, in order to overcome the weak point of power supply capacity algorithm on the sharing of load problem in the past.For this reason, the present invention adopts following technical scheme:

A kind of medium voltage distribution network method for analysis of available power supply capacity comprises the following steps:

The first step: set up the available power supply capacity model

The definition available power supply capacity refers to that power supply unit satisfies under the N-1 criterion condition in certain power supply area, consider the load supply ability of the maximum under the network practical operation situation, for the power distribution network that contains a plurality of interconnected transformer stations, it satisfies the available power supply capacity of N-1 criterion, be ASC, express with following formula:

Max?ASC＝∑R _iT _i

$s.t.\left\{\begin{array}{c}{R}_i{T}_i=\underset{j\∈{\mathrm{\Ω}}_1^{\left(i\right)}}{\mathrm{\Σ}}{\mathrm{Tr}}_{\mathrm{ij}}+\underset{j\∈{\mathrm{\Ω}}_2^{\left(i\right)}}{\mathrm{\Σ}}{\mathrm{Tr}}_{\mathrm{ij}}(\∀i)\\ {\mathrm{Tr}}_{\mathrm{ij}}+R_j{T}_j\≤k{R}_j(\∀i,j\∈{\mathrm{\Ω}}_1^{\left(i\right)})\\ {\mathrm{Tr}}_{\mathrm{ij}}+R_j{T}_j\≤R_j(\∀i,j\∈{\mathrm{\Ω}}_2^{\left(i\right)})\\ {\mathrm{Tr}}_{\mathrm{ij}}\≤{\mathrm{RL}}_{\mathrm{ij}}(\∀i,j\∈{\mathrm{\Ω}}_1^{\left(i\right)}\∪{\mathrm{\Ω}}_2^{\left(i\right)})\end{array}\right.---\left(1\right)$

In the formula (1), R _i, T _iBe respectively the rated capacity of main transformer i and this regional distribution network and satisfy maximum load rate under the N-1 criterion, Tr _IjFor main transformer i takes place under the N-1 failure condition to the size of main transformer j transfer load, k is that main transformer allows overload factor, RL in short-term _IjBe the power-carrying of interconnection between main transformer i and main transformer j, Ω ₁ ⁽ⁱ⁾And Ω ₂ ⁽ⁱ⁾Represent that respectively with main transformer i be the outer contact of set of contact main transformer and station main transformer set in the station in the main transformer contact unit at center;

Second step: establish total n seat transformer station in the survey region, be numbered 1,2 respectively ..., n, the main transformer platform number of corresponding each transformer station is respectively N ₁, N ₂..., N _n, get N _∑=N ₁+ N ₂+ ...+N _n, the communication relationship in the analysis and research zone between each main transformer forms main transformer communication relationship matrix L _Link,

$L_{\mathrm{link}}=\left[\begin{array}{cccccc}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>\; </figure-callout>}}_{\mathrm{1,1}}& ...& {\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1,i}& ...& {\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1,\mathrm{<figure-callout\; id="1"\; label="j\; ...\; L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">j</figure-callout>}}& ...& L_{}{}_{{1,N}_{\mathrm{\&Sigma;}}}\\ .& & .& & .& & .\\ .& ...& .& ...& .& ...& .\\ .& & .& & .& & .\\ L_{i,1}& ...& L_{i,i}& ...& L_{i,j}& ...& L_{{i,N}_{\mathrm{\&Sigma;}}}\\ .& & .& & .& & .\\ .& ...& .& ...& .& ...& .\\ .& & .& & .& & .\\ L_{j,1}& ...& L_{j,i}& ...& L_{j,j}& ...& L_{{j,N}_{\mathrm{\&Sigma;}}}\\ .& & .& & .& & .\\ .& ...& .& ...& .& ...& .\\ .& & .& & .& & .\\ L_{N_{\mathrm{\&Sigma;}},1}& ...& L_{N_{\mathrm{\&Sigma;}},i}& ...& L_{N_{\mathrm{\&Sigma;}},j}& ...& L_{N_{\mathrm{\&Sigma;}},N_{\mathrm{\&Sigma;}}}\end{array}\right]$

L in the formula _{I, j}Represent that there are communication relationship in i platform main transformer and j platform main transformer, get L when having communication relationship _{I, j}=1, otherwise L _{I, j}=0, there is communication relationship between regulation main transformer and self, promptly get L _{I, i}=1; Under i platform main transformer breaks down situation, its on-load can be transferred to j platform main transformer by the interconnection switch action, i=1,2,3 ..., N _∑, j=1,2,3 ..., N _∑

The 3rd goes on foot: that gets in touch with between pressing the interior contact in station and standing is different, to L _LinkMatrix carries out piecemeal, and to according to formula (2) to main transformer communication relationship matrix L _LinkRevise:

$L_{\mathrm{link}}=\left[\begin{array}{ccccccccc}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>\; </figure-callout>}}_{\mathrm{1,1}}& ...& {\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1,N_1}& {\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1,{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">N</figure-callout>}}_1+1}& ...& {\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1,{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}& ...& ...& {\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1,N_{\mathrm{\&Sigma;}}}\\ ...& ...& ...& ...& ...& ...& ...& ...& ...\\ {\mathrm{<figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>\; </figure-callout>}}_{N_{}{}_{}}& ...& {\mathrm{<figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}& {\mathrm{<figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}& ...& {\mathrm{<figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}& ...& ...& {\mathrm{<figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}\\ {\mathrm{<figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}& ...& {\mathrm{<figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}& {\mathrm{<figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}& ...& {\mathrm{<figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}& ...& ...& {\mathrm{<figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}\\ ...& ...& ...& ...& ...& ...& ...& ...& ...\\ {\mathrm{<figure-callout\; id="2"\; label="L\; N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="L\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>\; </figure-callout>}}_{N_{}{}_{}}& ...& {\mathrm{<figure-callout\; id="2"\; label="L\; N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}& {\mathrm{<figure-callout\; id="2"\; label="L\; N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}& ...& {\mathrm{<figure-callout\; id="2"\; label="L\; N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}& ...& ...& {\mathrm{<figure-callout\; id="2"\; label="L\; N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">L</figure-callout>}}_{N_{}}\\ ...& ...& ...& ...& ...& ...& ...& ...& ...\\ ...& ...& ...& ...& ...& ...& ...& ...& ...\\ L_{N_{\mathrm{\&Sigma;}},1}& ...& L_{N_{\mathrm{\&Sigma;}},N_1}& L_{N_{\mathrm{\&Sigma;}},{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">N</figure-callout>}}_1+1}& ...& L_{N_{\mathrm{\&Sigma;}},{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}& ...& ...& L_{N_{\mathrm{\&Sigma;}},N_{\mathrm{\&Sigma;}}}\end{array}\right]$

In the formula (2), the submatrix S on the diagonal positions of matrix in block form _{I, i}Expression, i is the power transformation station number, S _{I, i}The contact situation of expression transformer station i inside; Non-leading diagonal submatrix is with S _{I, j}Expression, i wherein, j represents power transformation station number, S _{I, j}The expression i of transformer station, the contact situation between j, according to the inside and outside communication relationship in station L _LinkMatrix is divided into contact matrix L in the station _Link ^InWith the outer contact in station matrix L _Link ^Out, the communication relationship in being used for respectively representing standing between main transformer, the communication relationship between outer main transformer of standing;

The 4th step: definition capacity matrix

The corresponding liaison centre of each element representation of R matrix main transformer capacity, and according to formula The R matrix is revised;

R is as follows for definition sharing of load matrix T:

Tr matrix element Tr _IjChange the on-load size to j platform main transformer when representing i platform main transformer generation N-1, main transformer i need be to the main transformer j transfer load Tr that gets in touch with it _{I, j}For:

${\mathrm{Tr}}_{i,j(i\&NotEqual;j)}=R_{i,j}^{\&prime;}-R_j\&times;\frac{\underset{\underset{j\&NotEqual;i}{j=1}}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}{R}_{i,j}^{\&prime;}}{\underset{j=1}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}{R}_j\&times;L_{i,j}}---\left(4\right)$

The interconnection power-carrying matrix that definition is represented suc as formula (5):

RL matrix element RL _IjRepresent i, the maximum transmission capacity that allows between j platform main transformer;

Define main transformer maximum load rate matrix T suc as formula (6),

$T=\left[\begin{array}{ccccccccc}{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="T"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>\; </figure-callout>}}_{\mathrm{1,1}}& ...& {\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,N_1}& {\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">N</figure-callout>}}_1+1}& ...& {\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}& ...& ...& {\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,N_{\mathrm{\&Sigma;}}}\\ ...& ...& ...& ...& ...& ...& ...& ...& ...\\ {\mathrm{<figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>\; </figure-callout>}}_{N_{}{}_{}}& ...& {\mathrm{<figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}& {\mathrm{<figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}& ...& {\mathrm{<figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}& ...& ...& {\mathrm{<figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}\\ {\mathrm{<figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}& ...& {\mathrm{<figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}& {\mathrm{<figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}& ...& {\mathrm{<figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}& ...& ...& {\mathrm{<figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}\\ ...& ...& ...& ...& ...& ...& ...& ...& ...\\ {\mathrm{<figure-callout\; id="2"\; label="T\; N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="T\; N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">T</figure-callout>\; </figure-callout>}}_{N_{}{}_{}}& ...& {\mathrm{<figure-callout\; id="2"\; label="T\; N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}& {\mathrm{<figure-callout\; id="2"\; label="T\; N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}& ...& {\mathrm{<figure-callout\; id="2"\; label="T\; N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}& ...& ...& {\mathrm{<figure-callout\; id="2"\; label="T\; N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">T</figure-callout>}}_{N_{}}\\ ...& ...& ...& ...& T_{i,j}& ...& ...& ...& ...\\ ...& ...& ...& ...& ...& ...& ...& ...& ...\\ T_{N_{\mathrm{\&Sigma;}},1}& ...& T_{N_{\mathrm{\&Sigma;}},N_1}& T_{N_{\mathrm{\&Sigma;}},{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">N</figure-callout>}}_1+1}& ...& T_{N_{\mathrm{\&Sigma;}},{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HSA00000026576900022.png,HSA00000026576900023.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}& ...& ...& T_{N_{\mathrm{\&Sigma;}},N_{\mathrm{\&Sigma;}}}\end{array}\right]---\left(6\right)$

Element T in the T matrix _{I, j}Being illustrated in the i main transformer is in the contact unit of liaison centre, satisfying under the N-1 criterion, the maximum of j main transformer allows load factor, calculates the load factor of interior off-diagonal position, station main transformer, the outer main transformer of standing in liaison centre's main transformer, the T matrix respectively according to formula (7);

$T_{i,i}=\frac{\underset{\underset{j\&NotEqual;i}{j=1}}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}(1-T_{i,j})R_j{L}_{i,j}}{R_i}$

$T_{i,j}=\frac{R_{i,j}^{\&prime;}-{\mathrm{Tr}}_{i,j}-\underset{k=1}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}({\mathrm{Tr}}_{i,k}-\min [{\mathrm{RL}}_{i,k},{\mathrm{Tr}}_{i,k}\left]\right)}{R_j}---\left(7\right)$

$T_{i,j}=\frac{R_{i,j}^{\&prime;}-\min [{\mathrm{RL}}_{i,j},{\mathrm{Tr}}_{i,j}]}{R_j}$

The 5th step: system's available power supply capacity calculates

Power supply capacity, network transitions power supply capacity are respectively in the available power supply capacity of whole network, the distribution website:

$\mathrm{ASC}=\underset{i=1}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}{T}_{i(N-1)}\%R_i$

${\mathrm{ASC}}_{\mathrm{in}}=k\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(\underset{j=1,j\&Element;i}{\overset{N_i}{\text{\&Sigma;}}}{R}_j-\mathrm{Max}\{R_j\left\}\right)---\left(8\right)$

ASC _out＝ASC-ASC _in

The 6th step: location weak spot

Definition transfering channel bottleneck matrix V=Max{Tr-RL, 0}, matrix element have reflected the relation between load transfer demand and permission transfer amount, if matrix element V _Ij＞0, show i, the transfering channel capacity limit between the j main transformer electrical network available power supply capacity, this circuit is exactly the weak spot of electrical network.

The 7th step: obtain critical capacity

Definition transfering channel critical capacity matrix U=U[u _Ij]=Max (Tr, Tr ^T), matrix element u _IjExpression i, the peak load size that need shift between the j main transformer, u _IjFor the critical capacity of transfering channel, at i, when the transfering channel element is selected between the j main transformer, u _IjBe the critical value of element volume, the selection capacity reaches u _IjElement get final product.

The present invention uses for reference the notion of available transmission capacity, defined the available power supply capacity (ASC) of medium voltage distribution network, available power supply capacity computation model and computational analysis method have been proposed, and on the available power supply capacity basis, proposed to locate fast the weak spot of restriction available power supply capacity in the rack, obtained the analytical method of the required smallest elements capacity of interconnection by the critical capacity matrix by transfering channel bottleneck matrix.

Description of drawings

Fig. 1: the whole implementation flow chart of the model of medium voltage distribution network available power supply capacity of the present invention and computational methods;

Fig. 2: the main transformer interconnecting relation schematic diagram of example network;

Fig. 3: two main transformers allow interconnected transformer station seat number and main transformer maximum load rate relation curve under the overload situations;

Fig. 4: three main transformers allow interconnected transformer station seat number and main transformer maximum load rate relation curve under the overload situations;

Fig. 5: four main transformers allow interconnected transformer station seat number and main transformer maximum load rate relation curve under the overload situations.

Embodiment

At first introduce the available power supply capacity model that the present invention proposes below.

Available power supply capacity refers to that power supply unit satisfies under the N-1 criterion condition in certain power supply area, considers the load supply ability of the maximum under the network practical operation situation.The size of electrical network available power supply capacity depends on main transformer power supply capacity and mains supply transfer ability in the transformer station station.According to the basic definition of available power supply capacity of the present invention, the load of taking into account under the N-1 failure mode changes band, the power supply capacity of a certain transformer station for power supply capacity in this transformer station station add contiguous transformer station can change band the load total amount with.The voltage constraint is one of constraints of electrical network available power supply capacity calculating, but current domestic city power distribution network circuit is shorter, voltage can meet the demands, so do not consider the voltage constraint in the model, for the power distribution network that contains a plurality of interconnected transformer stations generally, its available following formula of available power supply capacity (Available Supply Capability is called for short ASC) that satisfies the N-1 criterion is expressed:

Max?ASC＝∑R _iT _i

$s.t.\left\{\begin{array}{c}{R}_i{T}_i=\underset{j\&Element;{\mathrm{\&Omega;}}_1^{\left(i\right)}}{\mathrm{\&Sigma;}}{\mathrm{Tr}}_{\mathrm{ij}}+\underset{j\&Element;{\mathrm{\&Omega;}}_2^{\left(i\right)}}{\mathrm{\&Sigma;}}{\mathrm{Tr}}_{\mathrm{ij}}(\&ForAll;i)\\ {\mathrm{Tr}}_{\mathrm{ij}}+R_j{T}_j\&le;k{R}_j(\&ForAll;i,j\&Element;{\mathrm{\&Omega;}}_1^{\left(i\right)})\\ {\mathrm{Tr}}_{\mathrm{ij}}+R_j{T}_j\&le;R_j(\&ForAll;i,j\&Element;{\mathrm{\&Omega;}}_2^{\left(i\right)})\\ {\mathrm{Tr}}_{\mathrm{ij}}\&le;{\mathrm{RL}}_{\mathrm{ij}}(\&ForAll;i,j\&Element;{\mathrm{\&Omega;}}_1^{\left(i\right)}\&cup;{\mathrm{\&Omega;}}_2^{\left(i\right)})\end{array}\right.---\left(1\right)$

In the formula (1), R _i, T _iBe respectively the rated capacity of main transformer i and this regional distribution network and satisfy maximum load rate under the N-1 criterion, Tr _IjFor main transformer i takes place under " N-1 " failure condition to the size of main transformer j transfer load, k is that main transformer allows overload factor, RL in short-term _IjPower-carrying for interconnection between main transformer i and main transformer j.Ω ₁ ⁽ⁱ⁾And Ω ₂ ⁽ⁱ⁾Represent that respectively with main transformer i be the outer contact of set of contact main transformer and station main transformer set in the station in the main transformer contact unit at center.

The target function of formula (1) is the maximum available power supply capacity of system that satisfies all main transformer N-1 criterions, is expressed as the linear forms of maximum load rate.Constraints is to be the main transformer contact unit { T at center with main transformer i _i, Ω ₁ ⁽ⁱ⁾, Ω ₂ ⁽ⁱ⁾N-1 criterion constraint, be called i group constraints, comprise the constraint of two classes, the one, load balancing constraint, the 2nd, the not out-of-limit physical constraint of loading.When the equality constraint formula was represented main transformer i fault, the normal institute of main transformer i on-load at first was transferred to all the other main transformer (Ω in the station before the accident ₁ ⁽ⁱ⁾) changeing band, remainder is transferred to the contact main transformer (Ω at other station ₂ ⁽ⁱ⁾) change band, belong to first class constraint; Institute supply to load k times that is no more than rated capacity after main transformer j accepted the transfer load of fault main transformer i in three inequality constraintss were represented respectively to stand; Contact main transformer j accepts not overload after the transfer load of fault main transformer i; Transfer load is no more than the power-carrying of interconnection between main transformer, all belongs to second class constraint.

Be the detailed description of available power supply capacity computational methods of the present invention below

If total n seat transformer station is numbered 1,2 respectively in the survey region ..., n, the main transformer platform number of corresponding each transformer station is respectively N ₁, N ₂..., N _nGet N ∑=N ₁+ N ₂+ ...+N _n, represent the total platform number of this regional main transformer.

The main transformer communication relationship is analyzed

Communication relationship in the analysis and research zone between each main transformer forms main transformer communication relationship matrix L _Link,

$L_{\mathrm{link}}=\left[\begin{array}{ccccccc}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>\; </figure-callout>}}_{\mathrm{1,1}}& ...& {\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1,i}& ...& {\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1,j}& ...& {\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{{1,N}_{\mathrm{\&Sigma;}}}\\ .& & .& & .& & .\\ .& ...& .& ...& .& ...& .\\ .& & .& & .& & .\\ L_{i,1}& ...& L_{i,i}& ...& L_{i,j}& ...& L_{{i,N}_{\mathrm{\&Sigma;}}}\\ .& & .& & .& & .\\ .& ...& .& ...& .& ...& .\\ .& & .& & .& & .\\ L_{j,1}& ...& L_{j,i}& ...& L_{j,j}& ...& L_{{j,N}_{\mathrm{\&Sigma;}}}\\ .& & .& & .& & .\\ .& ...& .& ...& .& ...& .\\ .& & .& & .& & .\\ L_{N_{\mathrm{\&Sigma;}},1}& ...& L_{N_{\mathrm{\&Sigma;}},i}& ...& L_{N_{\mathrm{\&Sigma;}},j}& ...& L_{N_{\mathrm{\&Sigma;}},N_{\mathrm{\&Sigma;}}}\end{array}\right]$

L in the formula _{I, j}Represent that there are communication relationship in i platform main transformer and j platform main transformer, get L when having communication relationship _{I, j}=1, otherwise L _{I, j}=0, there is communication relationship between regulation main transformer and self, promptly get L _{I, i}=1; Under i platform main transformer breaks down situation, its on-load can be transferred to j platform main transformer by the interconnection switch action, i=1,2,3 ..., N _∑, j=1,2,3 ..., N _∑, N _∑The total platform number of main transformer in the expression institute survey region;

According to the inside and outside communication relationship in station L _LinkMatrix is divided into contact matrix L in the station _Link ^InWith the outer contact in station matrix L _Link ^Out, the communication relationship in being used for respectively representing standing between main transformer, the communication relationship between outer main transformer of standing.By formula

Connection matrix is revised.

Contact unit maximum load rate

The definition capacity matrix

The corresponding liaison centre of each element representation of R matrix main transformer capacity, and according to formula

The R matrix is revised.

R is as follows for definition sharing of load matrix T:

Tr matrix element Tr _IjChange the on-load size to j platform main transformer when representing i platform main transformer generation N-1.According to the principle that makes full use of the main transformer redundancy capacity, main transformer i need be to the main transformer j transfer load Tr that gets in touch with it _{I, j}For:

${\mathrm{Tr}}_{i,j(i\&NotEqual;j)}=R_{i,j}^{\&prime;}-R_j\&times;\frac{\underset{\underset{j\&NotEqual;i}{j=1}}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}{R}_{i,j}^{\&prime;}}{\underset{j=1}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}{R}_j\&times;L_{i,j}}---\left(4\right)$

For analyzing of the influence of interconnection limit transmission capacity, the interconnection power-carrying matrix that definition is represented suc as formula (5) to available power supply capacity:

RL matrix element RL _IjRepresent i, the maximum transmission capacity that allows between j platform main transformer.

Define main transformer maximum load rate matrix T suc as formula (5),

Element T in the T matrix _{I, j}Being illustrated in the i main transformer is in the contact unit of liaison centre, is satisfying under the N-1 criterion, and the maximum of j main transformer allows load factor.Matrix T is divided load factor submatrix according to the outer contact relation in contact in the station and station for being deformed in formula (6) frame with the station owner.

Consider the transfering channel capacity, the outer load of standing can't change band fully and have the main transformer of load rejection, and the secondary distribution of loading is given to the N-1 main transformer with the outer load that gets rid of in station and is become band with the station owner.The load factor formula of liaison centre's main transformer (shown in the leading diagonal position main transformer, formula 6 frame of broken lines), stand interior off-diagonal position main transformer (removing diagonal positions element part in the solid box), the outer main transformer of standing (solid box external position element) is respectively:

$T_{i,i}=\frac{\underset{\underset{j\&NotEqual;i}{j=1}}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}(1-T_{i,j})R_j{L}_{i,j}}{R_i}$

$T_{i,j}=\frac{R_{i,j}^{\&prime;}-{\mathrm{Tr}}_{i,j}-\underset{k=1}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}({\mathrm{Tr}}_{i,k}-\min [{\mathrm{RL}}_{i,k},{\mathrm{Tr}}_{i,k}\left]\right)}{R_j}---\left(7\right)$

$T_{i,j}=\frac{R_{i,j}^{\&prime;}-\min [{\mathrm{RL}}_{i,j},{\mathrm{Tr}}_{i,j}]}{R_j}$

System's available power supply capacity calculates

The every column element of T matrix is represented the maximum load rate of same main transformer in difference contact unit, and the actual loading rate should be minimum value in these row.

On the basis that all main transformers contact unit available power supply capacities are analyzed, can obtain comprehensively that power supply capacity, network transitions power supply capacity are respectively in the available power supply capacity, distribution website of whole network:

$\mathrm{ASC}=\underset{i=1}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}{T}_{i(N-1)}\%R_i$

${\mathrm{ASC}}_{\mathrm{in}}=k\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(\underset{j=1,j\&Element;i}{\overset{N_i}{\text{\&Sigma;}}}{R}_j-\mathrm{Max}\{R_j\left\}\right)---\left(8\right)$

ASC _out＝ASC-ASC _in

The weak spot location

V matrix in the available power supply capacity computational process contains some very important information, can observe the reason that influences power distribution network available power supply capacity size, and the weak spot of location power distribution network is for power distribution network optimization provides foundation and basic scheme.

Definition transfering channel bottleneck matrix V=Max{Tr-RL, 0}, the element of matrix V illustrate that greater than 0 the transfering channel capacity is too little, have limited available power supply capacity, numerical values recited has shown the limited degree size; The element of matrix V equals 0, illustrates that the transfering channel capacity can not influence the network available power supply capacity.

The V matrix element has reflected the relation between load transfer demand and permission transfer amount, as matrix element V _Ij＞0 o'clock, just show i, the transfering channel capacity limit between the j main transformer electrical network available power supply capacity, this circuit is exactly the weak spot of electrical network.

Critical capacity is analyzed

Because the restriction of transfering channel capacity, the available power supply capacity of network can be affected, if what one is particularly good at knows earlier that to transfering channel amount of capacity demand excavation network potential that just can be bigger makes the available power supply capacity of network bigger.

Definition transfering channel critical capacity matrix U=U[u _Ij]=Max (Tr, Tr ^T), matrix element u _IjExpression i, the peak load size that need shift between the j main transformer, u _IjCritical capacity for transfering channel.At i, when the transfering channel element is selected between the j main transformer, u _IjBe the critical value of element volume, the selection capacity reaches u _IjElement get final product, the element of excess capacity can not increase the network power supply ability.

About the model of medium voltage distribution network available power supply capacity and the whole implementation flow process of computational methods, can be referring to Fig. 1.

Be that example is found the solution and analyzed below

Certain power distribution network is based on cable system, and built on stilts net is auxilliary.Built on stilts net generally adopts the connection type of the multi-joint network of many segmentations; Cable system mainly adopts " H " wiring.This power distribution network High Voltage Distribution Substations situation is as shown in table 1.

The contact situation of this network is as shown in the table:

Table 1 network contact situation list

Main transformer 1 title	Main transformer	2 titles	Contact power-carrying (MVA)
				Main transformer 1 of S1	No. two main transformers 2 of S1	??40
No. two main transformers 2 of S1	Main transformer	3 of S2	??6.35
				No. two main transformers 2 of S1	Main transformer	5 of S3	??11.3
Main transformer 3 of S2	No. two main transformers 4 of S2	??40
			Main transformer 3 of S2	Main transformer	5 of S3	??7.64
Main transformer 3 of S2	No. two main transformers 6 of S3	??2.055
			No. two main transformers 4 of S2	Main transformer	5 of S3	??8.83
No. two main transformers 4 of S2	No. two main transformers 6 of S3	??2.055

Main transformer 1 title	Main transformer	2 titles	Contact power-carrying (MVA)
				Main transformer 5 of S3	No. two main transformers 6 of S3	??63

One, the main transformer communication relationship is analyzed

Main transformer of S1 among Fig. 2, No. two main transformers of S1, main transformer of S2, No. two main transformers of S2, main transformer of S3, No. two main transformers in Anshan are numbered 1,2,3,4,5,6 respectively, can obtain communication relationship matrix L between the main transformer _Link:

$L_{\mathrm{link}}=\left[\begin{array}{ccccc}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>\; </figure-callout>}}_{\mathrm{1,1}}& ...& {\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1,i}& ...& {\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">\; <figure-callout\; id="6"\; label="L"\; filenames="HSA00000026576900023.png"\; state="\{\{state\}\}">L</figure-callout>\; </figure-callout>}}_{\mathrm{1,6}}\\ .& & .& & .\\ .& ...& .& ...& .\\ .& & .& & .\\ L_{i,1}& ...& L_{i,i}& ...& L_{i,6}\\ .& & .& & .\\ .& ...& .& ...& .\\ .& & .& & .\\ {\mathrm{<figure-callout\; id="6"\; label="L"\; filenames="HSA00000026576900023.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="L"\; filenames="HSA00000026576900011.png,HSA00000026576900022.png"\; state="\{\{state\}\}">L</figure-callout>\; </figure-callout>}}_{\mathrm{6,1}}& ...& {\mathrm{<figure-callout\; id="6"\; label="L"\; filenames="HSA00000026576900023.png"\; state="\{\{state\}\}">L</figure-callout>}}_{6,i}& ...& {\mathrm{<figure-callout\; id="6"\; label="L"\; filenames="HSA00000026576900023.png"\; state="\{\{state\}\}">\; <figure-callout\; id="6"\; label="L"\; filenames="HSA00000026576900023.png"\; state="\{\{state\}\}">L</figure-callout>\; </figure-callout>}}_{\mathrm{6,6}}\end{array}\right]=\left[\begin{array}{cccccc}1& 1& 0& 0& 0& 0\\ 1& 1& 1& 0& 1& 0\\ 0& 1& 1& 1& 1& 1\\ 0& 0& 1& 1& 1& 1\\ 0& 1& 1& 1& 1& 1\\ 0& 0& 1& 1& 1& 1\end{array}\right]$

$=\left[\begin{array}{cccccc}1& 1& & & & \\ 1& 1& & & & \\ & & 1& 1& & \\ & & 1& 1& & \\ & & & & 1& 1\\ & & & & 1& 1\end{array}\right]+\left[\begin{array}{cccccc}& & 0& 0& 0& 0\\ & & 1& 0& 1& 0\\ 0& 1& & & 1& 1\\ 0& 0& & & 1& 1\\ 0& 1& 1& 1& & \\ 0& 0& 1& 1& & \end{array}\right]$

$(L_{\mathrm{link}}^{\mathrm{in}}-I)k+L_{\mathrm{link}}^{\mathrm{out}}=$

$=\left[\begin{array}{cccccc}& 1.3& & & & \\ 1.3& & 1& & 1& \\ & 1& & 1.3& 1& 1\\ & & 1.3& & 1& 1\\ & 1& 1& 1& & 1.3\\ & & 1& 1& 1.3& \end{array}\right]$

$R=\left[\begin{array}{cccccc}40& & & & & \\ & 40& & & & \\ & & 40& & & \\ & & & 40& & \\ & & & & 63& \\ & & & & & 63\end{array}\right]$

$R^{\&prime;}=\{(L_{\mathrm{link}}^{\mathrm{in}}-I)k+L_{\mathrm{link}}^{\mathrm{out}}+I\}R$

$\left[\begin{array}{cccccc}1& 1.3& & & & \\ 1.3& 1& 1& & 1& \\ & 1& 1& 1.3& 1& 1\\ & & 1.3& 1& 1& 1\\ & 1& 1& 1& 1& 1.3\\ & & 1& 1& 1.3& 1\end{array}\right]\&CenterDot;\left[\begin{array}{cccccc}40& & & & & \\ & 40& & & & \\ & & 40& & & \\ & & & 40& & \\ & & & & 63& \\ & & & & & 63\end{array}\right]$

$=\left[\begin{array}{cccccc}40& 52& & & & \\ 52& 40& 40& & 63& \\ & 40& 40& 52& 63& 63\\ & & 52& 40& 63& 63\\ & 40& 40& 40& 63& 81.9\\ & & 40& 40& 81.9& 63\end{array}\right]$

It is as follows to get interconnection power-carrying matrix by table 1:

$\mathrm{RL}=\left[\begin{array}{cccccc}0& 40& & & & \\ 40& 0& 6.35& & 11.3& \\ & 6.35& 0& 40& 7.64& 2.055\\ & & 40& 0& 8.83& 2.055\\ & 11.3& 7.64& 8.83& 0& 63\\ & & 2.055& 2.055& 63& 0\end{array}\right]$

Obtain easily:

$\mathrm{Tr}=\left[\begin{array}{cccccc}0& 26& & & & \\ 18.12& 0& 6.12& & 9.64& \\ & 4.56& 0& 21.687& 7.182& 2.055\\ & & 23.953& 0& 8.568& 2.055\\ & 7.16& 7.16& 7.16& 0& 30.177\\ & & 2.055& 2.055& 45.392& 0\end{array}\right]$

It is as follows to get the maximum load rate matrix:

$T=\left[\begin{array}{cccccc}0.65& 0.65& & & & \\ 0.847& 0.847& 0.847& & 0.847& \\ & 0.886& 0.886& 0.7578& 0.886& 0.9674\\ & & 0.7012& 0.864& 0.864& 0.9674\\ & 0.821& 0.821& 0.821& 0.821& 0.821\\ & & 0.9486& 0.9486& 0.5795& 0.786\end{array}\right]$

(2) system's main transformer maximum permissible load rate is analyzed

The maximum that obtains each main transformer allows load factor column vector T _Max%:

T _max％＝[T _1(N-1)?T _2(N-1)?T _3(N-1)?T _4(N-1)?T _5(N-1)?T _6(N-1)] ^T

＝[65?65?70.12?75.78?57.95?78.6]

(3) system's available power supply capacity analysis-by-synthesis

The available power supply capacity of example network, the interior power supply capacity of standing and network transitions power supply capacity are respectively:

$\mathrm{ASC}=\underset{i=1}{\overset{6}{\mathrm{\&Sigma;}}}{T}_{i\max }\%\&times;R_i$

$=40\&times;65\%+40*65\%+40*70.12\%+40*75.78\%+63*57.95\%+63*78.6\%$

$=196.39\mathrm{MVA}$

ASC _in＝185.9MVA

ASC _out＝10.45MVA

Two, weak spot location and prioritization scheme

Example transfering channel bottleneck matrix V is as follows:

$V=\left[\begin{array}{cccccc}0& 0& & & & \\ 0& 0& 0& & 0& \\ & 0& 0& 0& 0& 5.157\\ & & 0& 0& 0& 6.513\\ & 0& 0& 0& 0& 0\\ & & 6.505& 6.505& 0& 0\end{array}\right]$

By the V matrix as can be known, the transfering channel capacity between the 2# main transformer of 2#-S3 station, 2#, S2 station, 1#-S3 station, S2 station is too small, has influenced the electrical network available power supply capacity, and these two transfering channels are the electrical network weak spot.

Three, transfering channel element critical capacity

The transfering channel critical capacity matrix U of example is as follows

$U=\left[\begin{array}{cccccc}0& 26& & & & \\ 26& 0& 6.12& & 9.64& \\ & 6.12& 0& 17.44& 7.182& 8.56\\ & & 17.44& 0& 8.568& 8.568\\ & 9.64& 7.182& 8.568& 0& 32.382\\ & & 8.56& 8.568& 32.382& 0\end{array}\right]$

Element representation critical capacity in the matrix U can be followed successively by certificate, selects each transfering channel element.With u ₂₃=6.12 is example, during transfering channel element selection between S1 station 2# main transformer and S2 station 1# main transformer, the selection capacity reaches the element of 6.12MVA.

Four, interconnected scale analysis

Supposing that each interconnected transforming plant main transformer platform counts unanimity, promptly all is that two main transformer transformer stations are interconnected, perhaps all is that three main transformer transformer stations are interconnected, and each transformer rated capacity is all consistent.

At this moment, $T_{\max }=\frac{k(N-1)P+(n-1)\mathrm{NP}}{\mathrm{nNP}}=\frac{k(N-1)+(n-1)N}{\mathrm{nN}};$

When k=1.3, $T_{\max }=1-\frac{1.3-0.3N}{\mathrm{nN}};$

Can obtain result as shown in table 2 below according to following formula.

The desirable net capability of table 2 transformer station internet and main transformer load factor and load transfer ability relation

Transformer station's (seat)	Main transformer (platform number)	Available power supply capacity (times separate unit main transformer capacity)	Main transformer maximum load rate	Transfer ability requires (times separate unit main transformer capacity)	The maximum overload factor that allows
						??1	??2	??1.3	??0.65	??0.0	??2.00
??1	??3	??2.6	??0.87	??0.0	??1.50
						??1	??4	??3.9	??0.98	??0.0	??1.33

Transformer station's (seat)	Main transformer (platform number)	Available power supply capacity (times separate unit main transformer capacity)	Main transformer maximum load rate	Transfer ability requires (times separate unit main transformer capacity)	The maximum overload factor that allows
						??2	??2	??3.3	??0.83	??0.7	??2.00
??2	??3	??5.6	??0.93	??0.4	??1.50
						??2	??4	??7.9	??0.99	??0.1	??1.33
??3	??2	??5.3	??0.88	??1.4	??2.00
						??3	??3	??8.6	??0.96	??0.8	??1.50
??3	??4	??11.9	??0.99	??0.2	??1.33
						??4	??2	??7.3	??0.91	??2.1	??2.00
??4	??3	??11.6	??0.97	??1.2	??1.50
						??4	??4	??15.9	??0.99	??0.3	??1.33
??5	??2	??9.3	??0.93	??2.8	??2.00
						??5	??3	??14.6	??0.97	??1.6	??1.50
??5	??4	??19.9	??1.00	??0.4	??1.33
						??6	??2	??11.3	??0.94	??3.5	??2.00
??6	??3	??17.6	??0.98	??2.0	??1.50
						??6	??4	??23.9	??1.00	??0.5	??1.33

Last table data march linearize is handled, studied two main transformers, three main transformers respectively, when four main transformer transformer stations are interconnected, the gradual change relation curve between interconnected transformer station seat number and the main transformer maximum load rate is shown in accompanying drawing 3, accompanying drawing 4, accompanying drawing 5.As seen from the figure, if adopt two main transformers or the interconnected mode of three main transformers, interconnected transformer station seat number should not surpass 4, and for four main transformer mutual contact modes, then interconnected transformer station should not be above 3.Surpass these values, little when increasing interconnected transformer station station number to the raising of main transformer load factor, meaningless increase the contact complexity of network.

Claims (1)

1. a medium voltage distribution network method for analysis of available power supply capacity comprises the following steps:

The first step: set up the available power supply capacity model

The definition available power supply capacity refers to that power supply unit satisfies under the N-1 criterion condition in certain power supply area, consider the load supply ability of the maximum under the network practical operation situation, for the power distribution network that contains a plurality of interconnected transformer stations, it satisfies the available power supply capacity of N-1 criterion, be ASC, express with following formula:

Max?ASC＝∑R _iT _i

$s.t.\left\{\begin{array}{c}{R}_i{T}_i=\underset{j\&Element;{\mathrm{\&Omega;}}_1^{\left(i\right)}}{\mathrm{\&Sigma;}}{\mathrm{Tr}}_{\mathrm{ij}}+\underset{j\&Element;{\mathrm{\&Omega;}}_2^{\left(i\right)}}{\mathrm{\&Sigma;}}{\mathrm{Tr}}_{\mathrm{ij}}(\&ForAll;i)\\ {\mathrm{Tr}}_{\mathrm{ij}}+R_j{T}_j\&le;k{R}_j(\&ForAll;i,j\&Element;{\mathrm{\&Omega;}}_1^{\left(i\right)})\\ {\mathrm{Tr}}_{\mathrm{ij}}+R_i{T}_j\&le;R_j(\&ForAll;i,j\&Element;{\mathrm{\&Omega;}}_2^{\left(i\right)})\\ {\mathrm{Tr}}_{\mathrm{ij}}\&le;{\mathrm{RL}}_{\mathrm{ij}}(\&ForAll;i,j\&Element;{\mathrm{\&Omega;}}_1^{\left(i\right)}\&cup;{\mathrm{\&Omega;}}_2^{\left(i\right)})\end{array}\right.---\left(1\right)$

In the formula (1), R _i, T _iBe respectively the rated capacity of main transformer i and this regional distribution network and satisfy maximum load rate under the N-1 criterion, Tr _IjFor main transformer i takes place under the N-1 failure condition to the size of main transformer j transfer load, k is that main transformer allows overload factor, RL in short-term _IjBe the power-carrying of interconnection between main transformer i and main transformer j, Ω ₁ ⁽ⁱ⁾And Ω ₂ ⁽ⁱ⁾Represent that respectively with main transformer i be the outer contact of set of contact main transformer and station main transformer set in the station in the main transformer contact unit at center;

Second step: establish total n seat transformer station in the survey region, be numbered 1,2 respectively ..., n, the main transformer platform number of corresponding each transformer station is respectively N ₁, N ₂..., N _n, get N _∑=N ₁+ N ₂+ ... + N _n, the communication relationship in the analysis and research zone between each main transformer forms main transformer communication relationship matrix L _Link,

$L_{\mathrm{link}}=\left[\begin{array}{ccccccc}{L}_{\mathrm{1,1}}& ...& L_{1,i}& ...& L_{1,i}& ...& L_{1,N_{\mathrm{\&Sigma;}}}\\ .& & .& & .& & .\\ .& ...& .& ...& .& ...& .\\ .& & .& & .& & .\\ L_{i,1}& ...& L_{i,j}& ...& L_{i,j}& ...& L_{i,N_{\mathrm{\&Sigma;}}}\\ .& & .& & .& & .\\ .& ...& .& & .& ...& .\\ .& & .& & .& & .\\ L_{j,1}& & L_{i,i}& ...& L_{j,j}& ...& L_{j,N_{\mathrm{\&Sigma;}}}\\ .& & .& & .& & .\\ .& ...& .& ...& .& ...& .\\ .& & .& & .& & .\\ L_{N_{\mathrm{\&Sigma;}},1}& ...& L_{N_{\mathrm{\&Sigma;}},i}& ...& L_{N_{\mathrm{\&Sigma;}},j}& ...& L_{N_{\mathrm{\&Sigma;}},N_{\mathrm{\&Sigma;}}}\end{array}\right]$

L in the formula _{I, j}Represent that there are communication relationship in i platform main transformer and j platform main transformer, get L when having communication relationship _{I, j}=1, otherwise L _{I, j}=0, there is communication relationship between regulation main transformer and self, promptly get L _{I, i}=1; Under i platform main transformer breaks down situation, its on-load can be transferred to j platform main transformer by the interconnection switch action, i=1,2,3 ..., N _∑, j=1,2,3 ..., N _∑

The 3rd goes on foot: that gets in touch with between pressing the interior contact in station and standing is different, to L _LinkMatrix carries out piecemeal, and to according to formula (2) to main transformer communication relationship matrix L _LinkRevise:

In the formula (2), the submatrix S on the diagonal positions of matrix in block form _{I, i}Expression, i is the power transformation station number, S _{I, i}The contact situation of expression transformer station i inside; Non-leading diagonal submatrix is with Si, and j represents, i wherein, and j represents power transformation station number, S _{I, j}The expression i of transformer station, the contact situation between j, according to the inside and outside communication relationship in station L _LinkMatrix is divided into contact matrix L in the station _Link ^InWith the outer contact in station matrix L _Link ^Out, the communication relationship in being used for respectively representing standing between main transformer, the communication relationship between outer main transformer of standing;

The 4th step: definition capacity matrix

, the corresponding liaison centre of each element representation of R matrix main transformer capacity, and according to formula

The R matrix is revised;

R is as follows for definition sharing of load matrix T:

Tr matrix element Tr _IjChange the on-load size to j platform main transformer when representing i platform main transformer generation N-1, main transformer i need be to the main transformer j transfer load Tr that gets in touch with it _{I, j}For:

${\mathrm{Tr}}_{i,j(j\&NotEqual;j)}=R_{i,j}^{\&prime;}-R_j\&times;\frac{\underset{\underset{j\&NotEqual;i}{j=1}}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}{R}_{i,j}^{\&prime;}}{\underset{j=1}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}{R}_j\&times;L_{i,j}}---\left(4\right)$

The interconnection power-carrying matrix that definition is represented suc as formula (5):

RL matrix element RL _IjRepresent i, the maximum transmission capacity that allows between j platform main transformer;

Define main transformer maximum load rate matrix T suc as formula (6),

$T=\left[\begin{array}{ccccccccc}{T}_{\mathrm{1,1}}& ...& T_{1,N_1}& T_{1,N_1+1}& ...& T_{1,N_2}& ...& ...& T_{1,N_{\mathrm{\&Sigma;}}}\\ ...& ...& ...& ...& ...& ...& ...& ...& \\ T_{N_1,1}& ...& T_{N_1,N_1}& T_{N_1,N_1+1}& ...& T_{N_1,N_2}& ...& ...& T_{N_1,N_{\mathrm{\&Sigma;}}}\\ T_{N_1+\mathrm{1,1}}& ...& T_{N_1+1,N_1}& T_{N_1+1,N_1+1}& ...& T_{N_1+1,N_2}& ...& ...& T_{N_1+1,N_{\mathrm{\&Sigma;}}}\\ ...& ...& ...& ...& ...& ...& ...& ...& \\ T_{N_2,1}& ...& T_{N_2,N_1}& T_{N_2,N_1+1}& ...& T_{N_2,N_2}& ...& ...& {T_{N_2,N_{\mathrm{\&Sigma;}}}}_{}\\ ...& ...& ...& ...& T_{i,j}& ...& ...& ...& ...\\ ...& ...& ...& ...& ...& ...& ...& ...& ...\\ T_{N_{\mathrm{\&Sigma;}},1}& ...& T_{N_{\mathrm{\&Sigma;}},N_1}& T_{N_{\mathrm{\&Sigma;}},N_1+1}& ...& T_{N_{\mathrm{\&Sigma;}},N_2}& ...& ...& T_{N_{\mathrm{\&Sigma;}},N_{\mathrm{\&Sigma;}}}\end{array}\right]---\left(6\right)$

Element T in the T matrix _{I, j}Being illustrated in the i main transformer is in the contact unit of liaison centre, satisfying under the N-1 criterion, the maximum of j main transformer allows load factor, calculates the load factor of interior off-diagonal position, station main transformer, the outer main transformer of standing in liaison centre's main transformer, the T matrix respectively according to formula (7);

$T_{i,i}=\frac{\underset{\underset{j\&NotEqual;i}{j=1}}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}(1-T_{i,j})R_j{L}_{i,j}}{R_i}$

$T_{i,j}=\frac{R_{i,j}^{\&prime;}-{\mathrm{Tr}}_{i,j}-\underset{k=1}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}({\mathrm{Tr}}_{i,k}-\min [{\mathrm{RL}}_{i,k},{\mathrm{Tr}}_{i,k}\left]\right)}{R_j}---\left(7\right)$

$T_{i,j}=\frac{R_{i,j}^{\&prime;}-\min [{\mathrm{RL}}_{i,j},{\mathrm{Tr}}_{i,j}]}{R_j}$

The 5th step: system's available power supply capacity calculates

Power supply capacity, network transitions power supply capacity are respectively in the available power supply capacity of whole network, the distribution website:

$\mathrm{ASC}=\underset{i=1}{\overset{N_{\mathrm{\&Sigma;}}}{\mathrm{\&Sigma;}}}{T}_{i(N-1)}\%R_i$

${\mathrm{ASC}}_{\mathrm{in}}=k\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(\underset{j=1,j\&Element;i}{\overset{N_i}{\mathrm{\&Sigma;}}}{R}_j-\mathrm{Max}\{R_j\left\}\right)---\left(8\right)$

ASC _out＝ASC-ASC _in

The 6th step: location weak spot

Definition transfering channel bottleneck matrix V=Max{Tr-RL, 0}, matrix element have reflected the relation between load transfer demand and permission transfer amount, if matrix element V _Ij＞0, show i, the transfering channel capacity limit between the j main transformer electrical network available power supply capacity, this circuit is exactly the weak spot of electrical network;

The 7th step: obtain critical capacity

Definition transfering channel critical capacity matrix U=U[u _Ij]=Max (Tr, Tr ^T), matrix element u _IjExpression i, the peak load size that need shift between the j main transformer, u _IjFor the critical capacity of transfering channel, at i, when the transfering channel element is selected between the j main transformer, u _IjBe the critical value of element volume, the selection capacity reaches u _IjElement get final product.

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