CN110619443B - Active power distribution network power supply capacity calculation method based on TSC curve - Google Patents
Active power distribution network power supply capacity calculation method based on TSC curve Download PDFInfo
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Abstract
The invention discloses a method for calculating the power supply capacity of an active power distribution network based on a TSC curve.A column write security domain is restricted for a given topological structure of the power distribution network, element parameters and a specific access position of a DG; then, sampling according to a certain step length in a state space, and generating a working point set to be judged; and secondly, screening out working points meeting the security domain constraint, screening out the working points with load growth criticality and load reduction criticality according to a critical load growth criterion and a critical load reduction criterion, drawing a power supply capacity upper limit curve and a power supply capacity lower limit curve, and calculating a power supply capacity index. The method divides the active power distribution network into a safety area and a boundary-crossing area for the active power distribution network power supply through the TSC curve, establishes visual relation between the system state and the capacity, can completely reflect the capacity limit of the active power distribution network under various loads/DGs, and has important significance for guiding power distribution network planning, such as net rack construction, DG site selection and volume fixing and the like.
Description
Technical Field
The invention belongs to active power distribution network planning, and particularly relates to a method for evaluating power supply capacity limit of an active power distribution network under various load/DG distribution.
Background
After a Distributed Generation (DG) is connected to a power distribution network, a conventional passive power distribution network becomes an active power distribution network. The active power distribution network has higher flexibility, has a power supply function and realizes electric energy distribution; and the device also has a digestion function, and realizes the in-situ digestion or the collection and delivery of the DG output. In a conventional passive power distribution network, a maximum Supply capacity (TSC) is commonly used [1 []To measure the capacity limit of the distribution network load. The literature is concerned [2][3] It is pointed out that TSC is only the maximum power supply capacity that can be achieved under certain specific load distributions, and cannot be achieved under many actual load distributions, and is therefore based on the distribution network security domain boundary [4]]The concept of a power supply capability curve is presented. The power supply capacity curve can completely evaluate the power supply capacity of the passive power distribution network, and the highest point of the curve is the TSC.
Researches show that the active power distribution network also has a power supply capacity curve, and a new safety characteristic is presented [4] [5] due to the existence of reverse power flow, and the power supply capacity curve is also different from a passive network, but the existing documents do not provide a power supply capacity calculation method of the active power distribution network, and the invention provides a power supply capacity calculation method of the active power distribution network.
[ reference documents ]
[1]Xiao J，Li F，Gu W，et al.Total Supply Capability and Its Extended Indices for Distribution Systems：Definetion，Model Calculation ADN Applications[J].Generation Trasmission&Distribution Iet.5.8(2011)：869-876.
[2]Xiao J，Zhang M，Bai L，et al.Boundary Supply Capability(BSC)for Distribution Systems：Concept，Indices and Calculation[J].Generation Trasmission&Distribution Iet.10.1049/iet-gtd.2017.0725.
[3] Xiaojing, zhang Miaomiao, serendipity, et al. 3326-3335.
[4]Zu G,Xiao J,Sun K.Mathematical Base and Deduction of Security Region for Distribution Systems with DER[J].IEEE Transactions on Smart Grid，2018：1-1.
[5] Xiaojun, national strength, zhou Huan, et al. 79-85.
Disclosure of Invention
Aiming at the prior art, the invention provides a method for calculating the power supply capacity of an active power distribution network based on a TSC curve. According to a given power distribution network topological structure, element parameters and specific access positions of DGs in a network frame, a TSC Curve (Total Supply Capacity Curve) is drawn, a safety area and a boundary-crossing area for power Supply of an active network are divided, an intuitive relation between a system state and capacity is established through calculation of the TSC Curve on power Supply capacity indexes, capacity limits of the active power distribution network under various loads/DGs can be completely reflected, and the method has important significance for power distribution network guidance planning, such as network frame construction, DG site selection and capacity fixing and the like.
In order to solve the technical problems, the invention provides a method for calculating the power supply capacity of an active power distribution network based on a TSC curve, which is used for obtaining the power supply capacity of the active power distribution network according to the following steps for a given topology structure of the power distribution network, element parameters and specific access positions of DGs,
firstly, column writing security domain constraints according to network frame parameters of an active power distribution network;
sampling according to a certain step length in a state space to generate a working point set to be judged;
step three, firstly, screening out working points meeting the security domain constraint, and then respectively screening out the working points with the load increasing criticality and the working points with the load reducing criticality according to a critical load increasing criterion and a critical load reducing criterion;
step four, sequencing the power supply capacity of the working point with the load growth criticality from small to large according to the absolute value, and drawing a power supply capacity upper limit curve TSC + curve (ii) a The power supply capacity of the working point with load reduction criticality is sorted from small to large according to the absolute value, and a power supply capacity lower limit curve TSC is drawn - curve ；
Step five, calculating the power supply capacity index, including calculating the TSC according to the power supply capacity upper limit curve + curve Obtaining an upper limit power supply capacity index, and according to the TSC - curve Obtaining a lower limit power supply capacity index;
the upper limit power supply capability index includes: TSC (maximum Power System controller) with upper limit curve + Upper limit curve minimum power supply capacity TSC + min And upper limit curve average power supply capability
Wherein, the TSC with the maximum power supply capacity of the upper limit curve + Is the upper limit curve TSC of power supply capacity + curve The maximum point of (4) is called maximum power supply capacity for short, and means that the maximum power supply capacity means the load which can be supplied under the most ideal condition of a power grid, and the upper limit curve minimum power supply capacity TSC + min Is the upper limit curve TSC of power supply capacity + curve The minimum point of (4) is called minimum power supply capacity for short, and means the load which can be supplied under the condition that the power grid is least ideal, and the average power supply capacity of an upper limit curve->
The power supply energy of the working point with load growth criticality selected in the third stepThe average force value, referred to as average power supply capacity for short, means the load that the power grid can supply on average when all loads and DG output are distributed;
the lower power supply capability indicator includes: lower limit curve maximum power supply capacity TSC - Lower limit curve minimum power supply capacity TSC - min And average power supply capacity of lower limit curve
Wherein,
lower limit curve maximum power supply capacity TSC - Is a lower limit curve TSC of power supply capacity - curve The highest point of (4) means the load power required for ensuring the safety of a power grid under the maximum DG output, and the TSC (thyristor controlled rectifier) with the minimum power supply capacity of a lower limit curve - min Is a lower limit curve TSC of power supply capacity - curve The lowest point of (A) means the load power required for ensuring the safety of the power grid under the DG minimum output, and the average power supply capacity of the lower limit curve
The mean value of the power supply capacity of the working points with load reduction criticality screened in the third step means that the supporting load required by the safety mean of the power grid is guaranteed when DG output is given priority.
Further, in the first step of the method for calculating the power supply capacity of the active power distribution network, the N-0 security domain model omega of the active power distribution network ADN As shown in formula (1), the working point of the active power distribution network comprises a load node W L And DG node W DG Wherein A is L Is a load coefficient matrix; a. The DG Is a DG coefficient matrix; the formula (1) has two expression forms of formula (1-1) and formula (1-2); the safety constraint comprises a forward power flow constraint and a reverse power flow constraint, the reverse power flow constraint is a left side constraint in the formula (1-1),
in the formula (1), omega ADN Indicating N-0 security of active power distribution networksA domain; w represents a working point; s. the Ln Representing the outflow power of the nth load node; s DGn Represents the outflow power of the nth DG node; r represents a network loss coefficient; c represents a constant vector; a is ij Representing the load or DG coefficients.
In the second step of the method for calculating the power supply capacity of the active power distribution network, each variable is uniformly increased in a state space according to the step length q according to the formula (2) to generate N uniform sampling points,
in the formula (2), S Limax And S DGimax Representing the upper limits of loads i and DG i, respectively.
In the third step of the method for calculating the power supply capacity of the active power distribution network, firstly, a matrix operator | · | non-conducting phosphor is defined 1 The meaning is that each column vector of the matrix is summed first, then the maximum value is taken, the mathematical expression is as follows,
in the formula (3), A m×n Representing a matrix having m rows and n columns, a ij Represents the ith row and the jth column element in the matrix;
1) And (3) screening working points with load growth criticality:
the part of the forward power flow constraint of the formula (1-1) is taken and the like, all load variables are covered, a strict load upper limit boundary is obtained, the working points on the boundary have load growth criticality, and the mathematical model is as follows,
in the formula (4), the reaction mixture is,
represents the jth oneA load upper bound boundary; c. C e A constant vector representing an equality constraint; c. C ne A constant vector representing an inequality constraint; a. The DGe A matrix of DG coefficients representing an equality constraint; a. The DGne Representing a DG coefficient matrix without equal constraints; a. The Le A load coefficient matrix representing an equality constraint; a. The Lne Representing a load coefficient matrix without equal constraints; a. The Le + And the load coefficient matrix represents the equal taking of the forward power flow constraint.
The screening process is as follows: (1) carrying out safety constraint verification on the uniform sampling points in the state space obtained in the step two, if the safety constraint verification is passed, reserving the uniform sampling points, and if not, not reserving the uniform sampling points; (2) carrying out equal constraint check on the sampling points reserved in the step (1), if the sampling points meet partial forward power flow constraint, and the like, reserving, and if not, not reserving; (3) strict criticality check of load increase is carried out on the sampling points reserved in the step (2), and the forward power flow constraint equation coefficient matrix in the step (2) is written in a column mode
If the criterion is met>
If yes, the sampling point is a boundary point meeting the load growth criticality, and if not, the sampling point is not reserved;
the strict criticality of the load increase refers to: any load add-on force will not meet the safety constraints, and the mathematical definition is as follows: known as W i ＝[S L1 ,...,S Ln ,...,W DGi ]∈Ω ADN When the nth load is increased and the other loads and DG output are unchanged, a new working point W is formed i ＝[S L1 …S Ln +ε,…,W DGi ]If it is to
And lim ε → 0 + Have>
Then W is i With strict criticality of load increase, W i The boundary is called the upper limit of the load and is marked as ^ 4>
2) Screening operating points with load reduction criticality:
the part of the backward power flow constraint of the formula (1-1) is taken and the like, and all load variables are covered to obtain a strict load lower limit boundary, the working points on the boundary have load reduction criticality, the mathematical model is as follows,
in the formula (5), the reaction mixture is,
represents the jth lower load bound; a. The Le - And representing a load coefficient matrix of equal inverse power flow constraint.
The screening process comprises the following steps: (1) carrying out safety constraint verification on the uniform sampling points in the state space obtained in the step two, if the safety constraint verification is passed, reserving the uniform sampling points, and if not, not reserving the uniform sampling points; (2) carrying out equal constraint check on the sampling points reserved in the step (1), if the sampling points meet partial reverse power flow constraint equal constraint check, reserving the sampling points, and if not, not reserving the sampling points; (3) strict criticality check of load reduction is carried out on the sampling points reserved in the step (2), and the coefficient matrix of the reverse power flow constraint equation in the step (2) is written in a column mode
If the criterion is met>
If yes, the sampling point is a boundary point satisfying the load reduction criticality, otherwise, the sampling point is not reserved;
the strict criticality of the load reduction means: any load shedding force will not meet the safety constraints, and the mathematical definition is as follows: known as W i ＝[S L1 ,...,S Ln ,...,W DGi ]∈Ω ADN The ith load is reduced, the other loads and DG output are unchanged, and a new working point W is formed i ＝[S L1 …S Ln -ε,…,W DGi ]If, if
And lim ε → 0 + Has a->
Then W is i With strict criticality of load shedding, W i The boundary is called the lower limit of load boundary and is marked as ^ 4>
In the fourth step of the method for calculating the power supply capacity of the active power distribution network, a power supply capacity upper limit curve TSC is drawn + curve : and (3) drawing the working points with load growth criticality obtained in the step three into a curve according to the sequence of absolute values from small to large by taking the number of the sampling points as an abscissa and the sum of the loads of the sampling points as an ordinate, wherein a mathematical model is as follows,
in formula (6), val (W) Li ) Represents a boundary point W i The sum of the loads of (a).
Drawing power supply capacity lower limit curve TSC - curve : drawing the working points with load reduction criticality obtained in the step three into a curve according to the sequence of absolute values from small to large by taking the number of the sampling points as an abscissa and the sum of the loads of the sampling points as an ordinate, wherein a mathematical model is as follows,
in formula (7), val (W) Li ) Represents a boundary point W i The sum of the loads of (a).
Compared with the prior art, the invention has the beneficial effects that:
the method for calculating the power supply capacity of the active power distribution network, provided by the invention, has the advantages that the TSC curve is drawn through a uniform sampling algorithm, the power supply of the active power distribution network is divided into a safety area and a boundary-crossing area, the intuitive relation between the system state and the capacity is established, the power supply capacity limit of the active power distribution network under the distribution of various loads/DGs can be completely evaluated through the calculation of the TSC curve on the power supply capacity index, and the method has important significance for guiding the power distribution network planning, such as the network frame construction, the DG site selection and the volume fixing and the like.
Drawings
FIG. 1 is a flow chart of a power capacity calculation process for an active power distribution network of the present invention;
FIG. 2 is a schematic view of an embodiment of the present invention;
FIG. 3 is a TSC graph obtained in accordance with an exemplary embodiment of the present invention, including a TSC upper power limit curve + curve And power supply capacity lower limit curve TSC - curve 。
Detailed Description
As shown in fig. 1, the TSC curve-based method for calculating the power supply capacity of the active power distribution network according to the present invention obtains the power supply capacity of the active power distribution network according to the following steps for a given topology of the power distribution network, component parameters, and specific access positions of DG,
firstly, column writing security domain constraints according to network frame parameters of an active power distribution network;
step two, defining two empty sets C 1 And C 2 Sampling all variables in a state space according to the step length q to generate N working point sets to be judged, and enabling a counting variable k =1;
step three, safety constraint verification is carried out on the kth working point: if the safety constraint check is not satisfied, judging whether k is equal to N, if k is equal to N, turning to the fourth step, if k is not equal to N, adding 1 to a counting variable k, and continuing to return to the third step; if the safety check is met, respectively judging whether a forward power flow constraint equation or a reverse power flow constraint equation is met, wherein (1) and (2) are carried out simultaneously:
(1) if the positive power flow constraint equation is not satisfied, judging whether k is equal to N, if k is equal to N, turning to the fourth step, if k is not equal to N, adding 1 to a counting variable k, and continuing to return to the third step; if the forward power flow constraint equality is satisfied, screening all the forward power flow constraint equalities, and writing the coefficient matrix A of the forward power flow constraint equality in parallel Le + If not, ║ -A Le + ║ 1 <0, judging whether k is equal to N, if k is equal to N, turning to the fourth step, if k is not equal to N, adding 1 to a counting variable k, and continuing to return to the third step; if ║ -A is satisfied Le + ║ 1 <0 then outputs the operating point to set C 1 Judging whether k is equal to N, if k is equal to N, turning to the fourth step, if k is not equal to N, adding 1 to a counting variable k, and continuing to return to the third step;
(2) if the reverse power flow constraint equation is not satisfied, judging whether k is equal to N, if k is equal to N, turning to the fourth step, if k is not equal to N, adding 1 to a counting variable k, and continuing to return to the third step; if the reverse power flow constraint equality is satisfied, screening all the reverse power flow constraint equalities, and writing a coefficient matrix A of the reverse power flow constraint equality in parallel Le - If not, ║ -A Le - ║ 1 <0, judging whether k is equal to N, if k is equal to N, turning to the fourth step, if k is not equal to N, adding 1 to a counting variable k, and continuing to return to the third step; if ║ -A is satisfied Le - ║ 1 <0 then outputs the operating point to the set C 2 Judging whether k is equal to N, if k is equal to N, turning to the fourth step, if k is not equal to N, adding 1 to a counting variable k, and continuing to return to the third step;
step four, pair set C 1 The working points with load growth criticality are sorted from small to large according to the absolute value of the power supply capacity, and a power supply capacity upper limit curve TSC is drawn + curve To set C 2 The working points with load reduction criticality are sorted from small to large according to the absolute value of the power supply capacity, and a power supply capacity lower limit curve TSC is drawn - curve ；
Step five, calculating the power supply capacity index, including the power supply capacity indexUpper limit curve TSC + curve Obtaining an upper limit power supply capacity index, and according to the TSC - curve Obtaining a lower limit power supply capacity index;
the upper limit power supply capability index includes: TSC (maximum Power System controller) with upper limit curve + Upper limit curve minimum power capability TSC + min And upper limit curve average power supply capability
Wherein,
TSC (maximum Power System controller) with upper limit curve + Is the upper limit curve TSC of power supply capacity + curve The highest point of (A) means the load which can be supplied under the most ideal condition of the power grid,
upper limit curve minimum power supply capability TSC + min Is the upper limit curve TSC of power supply capacity + curve The lowest point of the load, meaning the load that the grid can supply in the most undesirable situation,
upper limit curve average power supply capability
The mean value of the power supply capacity of the working points with load growth criticality screened out in the third step means the load which can be supplied by the power grid on average when all loads and DG output are distributed;
the lower power supply capability indicator includes: lower limit curve maximum power supply capacity TSC - Lower limit curve minimum power supply capacity TSC - min And average power supply capacity of lower limit curve
Wherein,
lower limit curve maximum power supply capability TSC - Is a lower limit curve TSC of power supply capacity - curve The highest point of (1) means the load power required for ensuring the safety of the power grid under the maximum DG output,
lower limit curve minimum power supply capability TSC - min Is a lower limit curve TSC of power supply capacity - curve The lowest point of (A) means the load power required for ensuring the safety of the power grid under the DG minimum output,
average power supply capacity of lower limit curve
The mean value of the power supply capacity of the working points with load reduction criticality screened out in the third step means the support load required for guaranteeing the safety mean of the power grid when the DG output is given priority.
The invention will be further described with reference to the following drawings and specific examples, which are not intended to limit the invention in any way.
In the basic case of the example, as shown in fig. 2, the feeder capacity is set to 1.00pu, the power range of a single load node is [0,1.00], the power range of a single DG node is [ -1.00,0], and the network loss coefficient r is 2%.
The method for calculating the power supply capacity of the active power distribution network based on the TSC curve carries out power supply capacity calculation on the above calculation example, and the implementation steps are as follows:
1) Column write security domain expressions
First, the security domain expression of this example is written according to the column of equation (1) see equation (8), and equations (8-1) to (8-4) represent the capacity constraints of the branches B1 to B4, respectively.
2) Generating state space sampling points
Secondly, sampling the state space according to the formula (2), setting the sampling step length to be 0.02, and obtaining 6765201 (514) sampling points to be determined, wherein each state quantity has 51 sampling intervals.
3) Screening criticality operating points
Thirdly, judging the criticality of each sampling point: and judging whether the load increase/reduction criticality is met or not according to the formula (4) and the formula (5), and if the load increase/reduction criticality is met, respectively setting the boundary points as the TSC upper limit curve and the TSC lower limit curve.
Here at a certain operating point W＝[S L1 ,S L2 ,S DG1 ,S DG2 ] T ＝[0.62,0.72,-0.24,-0.12] T The description is given for the sake of example.
The working point satisfies the forward power flow constraint equation of the formula (8-2), and a load coefficient matrix A of the forward power flow constraint equation and the like can be obtained Le + Is [1,1]According to the calculation rule of formula (3), ║ -A can be obtained Le + ║ 1 <0, the operating point has load growth criticality.
The specific sampling results are detailed in tables 1 and 2.
TABLE 1 TSC Upper limit Curve sampling points
TABLE 2 TSC lower limit curve sampling points
4) Drawing a power supply capacity curve
Then, the boundary points are sorted according to equations (6) and (7) to obtain respective curves. Because the number of the sampling points of each curve is different, in order to facilitate observation and comparison, the number of the sampling points of all the curves is enlarged to be equivalent to that of the curve with the largest number of the sampling points, and the sampling points are drawn in the same coordinate system, as shown in fig. 3. As can be seen from fig. 3:
1) The power supply capacity curve of active power distribution network has 2: a TSC upper limit curve and a TSC lower limit curve.
2) The curve is the "critical line" between the power supply regions. The upper limit boundary crossing area indicates that the load is too large to cause the power flow to cross the boundary, the lower limit boundary crossing area indicates that the load is too small to support DG consumption, and the reverse power flow crosses the boundary.
3) The TSC lower limit curve is equal to 0, the power grid operates in a pure current collection state, the lifting indicates that DG output exceeds the capacity of a feeder line, and the DG output of a load balancing part is needed to ensure the safety of the power grid.
5) Calculating a power supply capability index
The power supply capacity index of the active power distribution network is shown in table 3
TABLE 3 TSC index
The method divides the active power distribution network into the safety area and the boundary crossing area for the active power distribution network power supply through the TSC curve, establishes visual relation between the system state and the capacity, can completely reflect the capacity limit of the active power distribution network under various loads/DGs, and has important significance for guiding power distribution network planning, such as net rack construction, DG site selection and volume fixing and the like.
While the present invention has been described with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are illustrative only and not restrictive, and various modifications which do not depart from the spirit of the present invention and which are intended to be covered by the claims of the present invention may be made by those skilled in the art.
Claims (5)
1. A method for calculating the power supply capacity of an active power distribution network based on a TSC curve is characterized in that for a given power distribution network topology structure, element parameters and a specific access position of a DG, the power supply capacity of the active power distribution network is obtained according to the following steps,
firstly, column writing security domain constraint is carried out according to grid frame parameters of an active power distribution network;
sampling according to a certain step length in a state space to generate a working point set to be judged;
step three, firstly, screening out working points meeting the security domain constraint, and then respectively screening out the working points with the load increasing criticality and the working points with the load reducing criticality according to a critical load increasing criterion and a critical load reducing criterion;
step four, sequencing the power supply capacity of the working points with the load growth criticality from small to large according to the absolute value, and drawing the power supply capacityLimited curve TSC + curve (ii) a The power supply capacity of the working point with load reduction criticality is sorted from small to large according to the absolute value, and a power supply capacity lower limit curve TSC is drawn - curve ；
Step five, calculating the power supply capacity index, including calculating the TSC according to the power supply capacity upper limit curve + curve Obtaining an upper limit power supply capacity index, and according to the TSC - curve Obtaining a lower limit power supply capacity index;
the upper limit power supply capability index includes: TSC (maximum Power System controller) with upper limit curve + Upper limit curve minimum power supply capacity TSC + min And upper bound curve average power supply capability
Wherein,
TSC (maximum Power System controller) with upper limit curve + Is the upper limit curve TSC of power supply capacity + curve The highest point of (A) means the load which can be supplied under the most ideal condition of the power grid,
upper limit curve minimum power supply capability TSC + min Is the upper limit curve TSC of power supply capacity + curve The lowest point of the load, meaning the load that the grid can supply in the most undesirable situation,
upper limit curve average power supply capability
The mean value of the power supply capacity of the working points with load growth criticality screened out in the third step means the load which can be supplied by the power grid on average when all loads and DG output are distributed;
the lower power supply capability indicator includes: lower limit curve maximum power supply capacity TSC - Lower limit curve minimum power supply capacity TSC - min And lower limit curve average power supply capability
Wherein,
lower limit curve maximum power supply capacity TSC - Is a lower limit curve TSC of power supply capacity - curve The highest point of (1) means the load power required for ensuring the safety of the power grid under the maximum DG output,
lower limit curve minimum power supply capability TSC - min Is a power supply capacity lower limit curve TSC - curve The lowest point of (A) means the load power required for ensuring the safety of the power grid under the DG minimum output,
average power supply capacity of lower limit curve
The mean value of the power supply capacity of the working points with load reduction criticality screened in the third step means that the supporting load required by the safety mean of the power grid is guaranteed when DG output is given priority.
2. The TSC curve-based active power distribution network power supply capacity calculation method according to claim 1, wherein in the first step,
n-0 security domain model omega of active power distribution network ADN As shown in formula (1), the working point of the active power distribution network comprises a load node W L And DG node W DG Wherein A is L Is a load factor matrix; a. The DG Is a DG coefficient matrix; the formula (1) has two expression forms of formula (1-1) and formula (1-2); the safety constraint comprises a forward power flow constraint and a reverse power flow constraint, the reverse power flow constraint is a left side constraint in the formula (1-1),
in the formula (1), omega ADN Representing an N-0 security domain of the active power distribution network; w represents the operating point; s Ln Representing the outflow power of the nth load node; s. the DGn Represents the outflow power of the nth DG node; r represents a network loss coefficient; c represents a constant vector; a is ij Representing the load or DG coefficients.
3. The TSC curve-based active power distribution network power supply capacity calculation method of claim 2, wherein in the second step, each variable is uniformly increased in a state space according to a step length q according to the formula (2) to generate N uniform sampling points,
in the formula (2), S Limax And S DGimax Representing the upper limits of loads i and DG i, respectively.
4. The TSC curve-based active power distribution network power supply capacity calculation method of claim 3, wherein in step three, first, a matrix operator | · | | | computationally is defined 1 The meaning is that each column vector of the matrix is summed firstly, then the maximum value is taken, the mathematical expression is as follows,
in the formula (3), A m×n Representing a matrix having m rows and n columns, a ij Represents the ith row and the jth column element in the matrix;
1) Screening the working points with load growth criticality:
the part of the forward power flow constraint of the formula (1-1) is taken and the like, all load variables are covered, a strict load upper limit boundary is obtained, the working points on the boundary have load growth criticality, and the mathematical model is as follows,
in the formula (4), the reaction mixture is,
represents the jth upper load limit boundary; c. C e A constant vector representing an equality constraint; c. C ne A constant vector representing an inequality constraint; a. The DGe A matrix of DG coefficients representing an equality constraint; a. The DGne Representing a DG coefficient matrix without equal constraints; a. The Le A load coefficient matrix representing an equality constraint; a. The Lne Representing a load coefficient matrix without equal constraints; a. The Le + A load coefficient matrix representing the forward power flow constraint equal selection;
the process of screening the working points with load growth criticality is as follows:
(1) carrying out safety constraint verification on the uniform sampling points in the state space obtained in the step two, if the safety constraint verification is passed, reserving, and if not, not reserving;
(2) carrying out equal constraint check on the sampling points reserved in the step (1), if the sampling points meet partial forward power flow constraint, and the like, reserving, and if not, not reserving;
(3) and (3) carrying out strict criticality check of load increase on the sampling points reserved in the step (2), and writing the coefficient matrix of the forward power flow constraint equation in the step (2) in a column mode
If the criterion is met>
If yes, the sampling point is a boundary point meeting the load growth criticality, and if not, the sampling point is not reserved;
the strict criticality of the load increase refers to: any load add-on force will not meet the safety constraints, and the mathematical definition is as follows:
known as W i ＝[S L1 ,...,S Ln ,...,W DGi ]∈Ω ADN When the nth load is increased and the other loads and DG output are unchanged, a new working point W is formed i ＝[S L1 …S Ln +ε,…,W DGi ]If it is to
And lim ε → 0 + Has a->
Then W is i With strict criticality of load growth, W i The boundary is called the upper load limit boundary and is marked as +>
2) Screening operating points with load reduction criticality:
the part of the reverse power flow constraint of the formula (1-1) is taken and the like, all load variables are covered, a strict load lower limit boundary is obtained, the working points on the boundary have load reduction criticality, and the mathematical model is as follows,
in the formula (5), the reaction mixture is,
represents the jth lower load limit boundary; a. The Le - A load coefficient matrix representing the equal taking of the reverse power flow constraint;
the process of screening the operating points with load reduction criticality is as follows:
(1) carrying out safety constraint verification on the uniform sampling points in the state space obtained in the step two, if the safety constraint verification is passed, reserving, and if not, not reserving;
(2) carrying out equal constraint check on the sampling points reserved in the step (1), if the sampling points meet partial reverse power flow constraint equal constraint check, reserving the sampling points, and if not, not reserving the sampling points;
(3) strict criticality check of load reduction is carried out on the sampling points reserved in the step (2), and the coefficient matrix of the reverse power flow constraint equation in the step (2) is written in a column mode
If the criterion is met>
If yes, the sampling point is a boundary point satisfying the load reduction criticality, otherwise, the sampling point is not reserved;
the strict criticality of the load reduction means: any load shedding output will not meet the safety constraints, and the mathematical definition is as follows:
known as W i ＝[S L1 ,...,S Ln ,...,W DGi ]∈Ω ADN The ith load is reduced, other loads and DG output are unchanged, and a new working point W is formed i ＝[S L1 …S Ln -ε,…,W DGi ]If, if
And lim ε → 0 + Has a->
Then W is i With strict criticality of load shedding, W i The boundary is called the lower limit of load boundary and is marked as ^ 4>
5. The method for calculating the power supply capacity of the active power distribution network based on the TSC curve as claimed in claim 4, wherein in the fourth step, a TSC upper limit curve is drawn + curve : and (3) drawing the working points with load growth criticality obtained in the step three into a curve according to the sequence of absolute values from small to large by taking the number of the sampling points as an abscissa and the sum of the loads of the sampling points as an ordinate, wherein a mathematical model is as follows,
in formula (6), val (W) Li ) Represents the boundary point W i The sum of the loads of (a);
in the fourth step, a power supply capacity lower limit curve TSC is drawn - curve : drawing the working points with load reduction criticality obtained in the step three into a curve according to the sequence of absolute values from small to large by taking the number of the sampling points as an abscissa and the sum of the loads of the sampling points as an ordinate, wherein a mathematical model is as follows,
in formula (7), val (W) Li ) Represents a boundary point W i The sum of the loads of (a).
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