CN105552899A - Method for calculating recovery capability of power grid after blackout - Google Patents

Abstract

The invention discloses a method for calculating the recovery capability of a power grid after blackout. The method comprises the following steps: (1), identifying the specific state of a system after power failure, and obtaining data for calculating; (2), screening out available black-start machine sets in the system, and calculating the sum of capacities of all the black-start machine sets and the corresponding per-unit value; (3), calculating the average shortest distance from various machine sets to be recovered to the black-start machine sets and the average shortest distance from load nodes to various machine set nodes in the system, and calculating the average distance between the two; and (4), taking the per-unit value of the sum of the capacities of the black-start machine sets and the quotient of the average distance in the step (3) as the recovery capability of the power grid after blackout. The method disclosed by the invention has the benefits that: a quantitative means is provided for evaluating and analyzing the recovery capability of the power after blackout; the weak point of the power grid in the aspect of increasing the recovery capability is convenient to search; and the corresponding improved means is provided.

Description

Method for calculating power grid recovery force after blackout

Technical Field

The invention relates to a power grid index calculation method, in particular to a calculation method for calculating power grid resilience after a blackout.

Background

With the rapid development of economic society, the scale of a power system is larger and larger, and with the construction of an extra-high voltage alternating current-direct current power grid and the access of large-scale renewable energy bases such as large-scale wind power plants, photovoltaic power stations and the like to the power grid, the dynamic behavior of the power system becomes more and more complex, and the operating point of the power grid is closer to the safety limit point of the power grid by considering environmental problems and economic factors in the operation process of the power grid, so that the complexity of the operation and maintenance of the power grid is greatly increased. Therefore, when the local fault of the system is not properly processed, a large-area power failure accident of the system is likely to occur. For example, in 14 days 8 and 8 months in 2003, the most serious power failure accident in north america historically occurs, the power failure accident reaches many areas in the united states and canada, the load loss is 61.8GW, the number of affected people is 5000 ten thousand, and the occurrence reason is that short-circuit fault processing of a 345kV power transmission line is improper, so that the power flow is transferred in a large range, multiple power transmission lines are tripped in a chain manner due to overload, and finally a major power failure accident occurs; in 2006, 11/4 days, the European interconnected network has a major power failure accident, the national common loss load of Germany, French, ideation and the like is about 1600 ten thousand kW, and 1500 universal households are affected; in 11 months and 10 days in 2009, the brazil and Paraguay power grids have major power failure accidents, so that three 750kV lines trip, two +/-600 kV direct current lines are locked, the brazil power grid loses about 1700 ten thousand kW of power, the power failure range reaches 12 states in the Past and most areas of the neighboring country Paraguay, and 5000 to 6000 million people are affected; in 2012, 30 days and 31 days, two large-area power failure accidents occur continuously in northern and eastern areas of India, which cover more than half of the territory and directly influence the lives of 6 hundred million people. The operation experience of domestic and foreign power systems shows that although the stability and reliability of the system operation can be improved by applying a large amount of new technologies and new equipment in the power systems, the occurrence of heavy power failure still cannot be avoided.

The dependence degree of the modern society on reliable power supply is higher and higher, and once a large-area power failure accident happens, the influence and huge economic loss on social production and life can be brought. The data analysis of multiple major power failure accidents at home and abroad shows that the loss caused by the power failure accidents is in an exponential relation with the power failure time. The longer the system power off time, the more serious the adverse effect. After a power failure accident occurs, under the guidance of a corresponding recovery scheme, corresponding recovery operation is carried out as soon as possible, so that the recovery process of the system is accelerated, the power failure time of the system is shortened, and the influence and loss caused by the power failure accident of the system are reduced. The duration of the system recovery process is related to factors such as whether the recovery scheme is complete and the proficiency of dispatching personnel, and also related to the self rapid recovery capability of the power grid after the power grid is subjected to external disturbance, namely the recovery force of the power grid. The power grid restoration capability mainly considers the capability of the system for rapidly restoring various resources under the condition that the power grid has large-area power failure and other extreme accidents, which is not related to the traditional power system planning. The restoring force is an important characteristic of the smart grid, and the research on the restoring force of the power grid is a necessary trend of the development of the smart grid. The power grid restoring force is related to various factors such as a grid structure of a system, a power supply and load distribution, and the like, so that the power grid restoring force can be improved, the power grid development planning can be guided, the existing power grid can be analyzed, and corresponding improvement measures can be provided.

At present, research on the resilience of the power grid is just started, the evaluation theory and method research of the resilience of the power grid is yet to be carried out on further systematic results, the analysis of related factors is still in a qualitative analysis stage, and a tool for quantitative analysis is lacked.

Disclosure of Invention

The invention aims to solve the problems and provides a method for calculating the recovery force of a power grid after a blackout. The method for quantitatively calculating the restoring force of the power grid is provided by comprehensively considering the capacity and distribution of the black start unit and the unit to be restored, the grid structure, the distribution of the load stations and other factors which can be used in the power grid after the major power failure accident occurs, and provides a basis for guiding the planning of the power grid and the improvement of the restoring force of the power grid.

In order to achieve the purpose, the invention adopts the following specific scheme:

a method for calculating a power grid recovery force after a blackout comprises the following steps:

(1) the method comprises the steps that availability diagnosis is conducted on all power generation, transmission and transformation equipment in a system, and the number of black-start units and units to be recovered in the system and the corresponding unit capacity, the connection relation of available power transmission lines in the system and corresponding line parameters are obtained;

(2) establishing a weighted network connection matrix corresponding to the system according to the acquired data;

(3) screening out available black start units in the system, and calculating the sum of the capacities of all the available black start units and corresponding per unit values;

(4) calculating the average shortest distance from each unit to be recovered to the black start unit and the average shortest distance from the load node to each unit node in the system, and calculating the average distance between the two average shortest distances;

(5) and (4) according to the per unit value of the sum of the capacities of all the available black start units obtained in the step (3) and the average distance calculated in the step (4), obtaining the restoring force of the power grid after the blackout, and providing a reference basis for the development planning of the power grid.

In the step (1), the method for diagnosing the availability of all the power generation, transmission and transformation equipment in the system comprises the following steps:

and identifying and judging the operating states of all the power generation, transmission and transformation equipment in the system, and screening out the equipment in a fault state or a maintenance state, namely the equipment which is unavailable in the recovery process.

In the step (2), when a weighted network connection matrix M corresponding to the system is established, M is a square matrix, and the number of rows and columns is equal to the number of available power plant and substation nodes in the system;

when available transmission line l exists between node i and node j in system_ijWhen it is set up, the line l_ijPer unit value of line reactance of x_ijWhose corresponding element in the connection matrix M is M_ijAnd has M_ij＝M_ji＝x_ij(ii) a On the contrary, if no available transmission line exists between the node i and the node j in the system, M is used for judging whether the available transmission line exists between the node i and the node j_ij＝M_ji＝∞。

In the step (3), the average shortest distance from each unit to be recovered to the black-start unit in the system is determined according to the minimum value of the shortest distance from each unit to be recovered to each black-start unit.

Further, the shortest distance Dis from the unit i to be recovered to the black start unit j is calculated_ijIn the process, a node where a black start unit j is located is taken as a source point S, a node where a unit i to be recovered is located is taken as a target node t, and nodes in a weighting network connection matrix M are divided into two types, namely a set S and a set U: the set S is a set of target nodes which have already found the shortest path to the source point S, and the set U is a set of target nodes which have not calculated the shortest path to the source point S.

Further, the shortest distance Dis from the unit i to be recovered to the black start unit j is calculated by adopting a shortest path method_ijThe specific method comprises the following steps:

1) during initial calculation, the set S only contains the source point S, the set U contains all nodes except the source point S, and any point x, D [ x ] in the set U]Is the distance from the source point s to the point x, i.e. the value M of the corresponding element of the line between the source point s and the node x in the connection matrix M_sx；

2) Selecting a point x with the minimum D [ x ] from the set U, and then moving the point x from the set U to the set S;

3) for any node y in the remaining nodes of the set U, if there is D [ y [ ]]>D[x]+M_xyThen the distance D [ y ] from the source point s to the point y]Is set as D [ x ]]+M_xyWherein M is_xyThe numerical value of the corresponding element of the line between the node x and the node y in the connection matrix M;

4) selecting a point y with the minimum D [ y ] from the rest nodes, and then moving the point y from the set U to the set S;

5) repeating the step 3) and the step 4) until all the nodes in the set U are moved to the set S;

6) the shortest distance from the source point s to the target node t is D [ t ].

In the step (4), the average shortest distance from the load node to each unit node is determined according to the minimum value of the shortest distances from the unit i to be recovered to all the unit nodes.

Further, when the average shortest distance from the load node to each unit node is calculated, the load nodes are divided into two types: the load nodes are contained in the recovery paths corresponding to the minimum value of the shortest distance from each unit to be recovered to each black-start unit; the other class is not included in the load nodes in the path;

and clustering the nodes contained in the recovery paths corresponding to the minimum value of the shortest distance from each unit to be recovered to each black-start unit.

And further, calculating the shortest distance from the unit i to be recovered to all the unit nodes by adopting a shortest path method.

In the step (5), the restoring force of the power grid after the blackout is as follows: and (4) the quotient of the per unit value of the sum of the capacities of all the available black start units and the average distance calculated in the step (4).

The invention has the beneficial effects that:

firstly, the method for calculating the power grid restoring force after the blackout can conveniently calculate the restoring force of different power grids after the blackout accident and compare the restoring force with each other.

Secondly, the method for calculating the power grid restoring force after the blackout provides a quantitative means for evaluating and analyzing the restoring force of the power grid after the blackout, can conveniently find the weak point of the power grid in the aspect of improving the restoring force, and provides corresponding improvement measures.

Thirdly, the quantitative calculation method for calculating the power grid restoring force after the blackout provided by the invention can guide the power grid planning to be more visual and effective by taking the maximum power grid restoring force as a target.

Fourthly, when the restoring force of the power grid after the blackout is calculated, factors such as the capacity and the position of the black start unit in the power grid are comprehensively considered, so that the calculation result of the restoring force of the power grid is more objective, and the method can be used for guiding the distribution optimization and the capacity optimization of the black start unit.

Fifthly, the position relation between the unit to be recovered and the black start unit is considered, the starting process of the unit to be recovered in the black start process can be effectively reflected, and the actual recovery capability of the power grid after the fault occurs can be effectively reflected by the recovery force of the power grid.

Sixth, when the restoring force of the power grid after the power failure is calculated, the load nodes are classified, and the actual restoring process of the power grid after the power failure accident is more met.

Drawings

FIG. 1 is a flow chart of a method for calculating the recovery force of a power grid after a blackout according to the present invention;

fig. 2 is a diagram illustrating an IEEE30 node system according to an embodiment of the present invention.

Detailed Description

The invention is described in detail below with reference to the accompanying drawings:

a method for calculating a grid restoration force after blackout, as shown in fig. 1, includes the following steps:

(1) the method comprises the steps that availability diagnosis is conducted on all power generation, transmission and transformation equipment in a system, and the number of black-start units and units to be recovered in the system and the corresponding unit capacity, the connection relation of available power transmission lines in the system and corresponding line parameters are obtained;

(2) establishing a weighted network connection matrix corresponding to the system according to the acquired data;

when a weighted network connection matrix M corresponding to the system is established, M is a square matrix, and the number of rows and columns is equal to the number of available stations in the system. When there is a call line l available between node i and node j in the system_ijAnd line l_ijPer unit value of line reactance of x_ijThen connect the elements M in the matrix M_ij＝M_ji＝x_ij(ii) a On the contrary, if there is no available tie line between node i and node j in the system, M_ij＝M_jiInfinity. For a system with n sites, the corresponding connection matrix M is of the form as follows.

$M=\left[\begin{array}{ccccccc}{M}_{11}& M_{12}& \mathrm{...}& M_{1i}& M_{1j}& \mathrm{...}& M_{1n}\\ M_{21}& M_{22}& \mathrm{...}& M_{2i}& M_{2j}& \mathrm{...}& M_{2n}\\ .& .& & .& .& & .\\ .& .& & .& .& & .\\ .& .& \mathrm{...}& .& .& \mathrm{...}& .\\ M_{i1}& M_{i2}& \mathrm{...}& M_{ii}& M_{ij}& \mathrm{...}& M_{in}\\ M_{j1}& M_{j2}& \mathrm{...}& M_{ji}& M_{jj}& \mathrm{...}& M_{jn}\\ .& .& & .& .& & .\\ .& .& & .& .& & .\\ .& .& \mathrm{...}& .& .& \mathrm{...}& .\\ M_{n1}& M_{n2}& \mathrm{...}& M_{ni}& M_{nj}& \mathrm{...}& M_{nn}\end{array}\right]$

In the formula, for an arbitrary element M_ijAnd M_jiIn the presence of M_ij＝M_ji。

(3) Screening out available black start units in the system, and calculating the sum of the capacities of all the available black start units and corresponding per unit values;

the recovery process of the system after a large-area power failure accident comprises a black start stage, a net rack reconstruction stage and a load recovery stage. In the black start phase, the black start unit available in the system is started first. And after the black start unit is successfully started, providing required starting power for the rest units without self-starting capability to restart the grid connection. In the net rack reconstruction stage, important power transmission lines and important load stations in the system are gradually restored, a strong net rack is established to lay a foundation for subsequent load restoration, and in the load restoration stage, on the basis of early restorationAnd large-scale load recovery is carried out, the power failure load is recovered as soon as possible, and the power failure time of the system is shortened. The successful start of the black start unit is the start of the whole recovery process, and the capacity of the black start unit represents the capability of rapidly recovering after a large-area power failure accident occurs to the system and can be used as an important index for reflecting the recovery force of the power grid. After all available black start units in the system are screened out, the sum P of the capacities of all the black start units_blackThe calculation formula is shown below

$P_{blck}=\underset{i=1}{\overset{n}{\Σ}}{P}_i$

In the formula, n is the number of black start units available in the system; p_iThe capacity of the unit is black-start for the ith station. P_blackThe formula for calculating the per unit value of (A) is shown below

$P_{black}^{*}=\frac{P_{black}}{S_B}$

In the formula, S_BThe power base value selected in step S1.

(4) Calculating the average shortest distance from each unit to be recovered to the black start unit and the average shortest distance from the load node to each unit node in the system, and calculating the average distance between the two average shortest distances;

average shortest distance from each unit to be recovered to black start unitThe calculation formula is as follows:

$\stackrel{\‾}{L_S}=\frac{\underset{i=1}{\overset{m}{\Σ}}{L}_{Si}}{m}$

L_Si＝min(Dis_ij),j＝1,2,...,n

wherein m is the number of units to be recovered, n is the number of black start units, Dis_ijIs the shortest distance from the unit i to be recovered to the black start unit j, L_SiThe minimum value of the shortest distance from the unit i to be recovered to each black start unit.

Calculating the shortest distance Dis from the unit i to be recovered to the black start unit j_ijAnd taking the node where the black start unit j is located as a source point s, taking the node where the unit i to be recovered is located as a target node t, and calculating by using a shortest path algorithm. For the weighted network connection matrix M, the shortest path algorithm divides the nodes in M into two classes, which are respectively marked as a set S and a set U. Set S is a set of points for which the shortest path to source point S has been found, and set U is a set for which the shortest path to source point S has not been calculated. The shortest path algorithm comprises the following calculation steps:

1. during initial calculation, the set S only contains the source point S, the set U contains all nodes except the source point S, and any point x, D [ x ] in the set U]Is the distance from the source point s to the point x, i.e. the value M of the corresponding element of the line between the source point s and the node x in the connection matrix M_sx；

2. Selecting a point x with the minimum D [ x ] from the set U, and then moving the point x from the set U to the set S;

3. for any node y in the remaining nodes of the set U, if there is D [ y [ ]]>D[x]+M_xyThen the distance D [ y ] from the source point s to the point y]Is set as D [ x ]]+M_xy；

4. Repeating the step 2 and the step 3 until all the nodes in the set U are moved to the set S;

5. the shortest distance from the source point s to the target node t is D [ t ].

When the shortest distance from the load node to all the unit nodes is calculated, the load node is divided into two types: the load nodes are contained in the recovery paths corresponding to the minimum value of the shortest distance from each unit to be recovered to each black-start unit; the other class does not contain load nodes in the path. And for the first type of load nodes which are already included in the recovery path, the first type of load nodes are not considered, only the second type of load nodes are considered here, and the nodes included in the recovery path corresponding to the minimum value of the shortest distance from each unit to be recovered to each black-start unit are clustered. Average shortest distance from load node to each unit nodeIs calculated by the formula

$\stackrel{\‾}{L_{ld}}=\frac{\underset{i=1}{\overset{nld}{\Σ}}{L}_{ldi}}{nld}$

L_ldi＝min(Dis_ij),j＝1,2,...,nut

Wherein nld is the number of second type load nodes; nut is the number of all nodes in the group; dis (disease)_ijThe shortest distance from the load node i to the unit node j is obtained; l is_ldiThe minimum value of the shortest distance from the unit i to be recovered to all the unit nodes is obtained. In calculating Dis_ijThe shortest path algorithm is also used.

Andaverage value of (2)Is composed of

$\stackrel{\‾}{L}=\frac{\stackrel{\‾}{L_S}+\stackrel{\‾}{L_{ld}}}{2}$

(5) And (4) according to the per unit value of the sum of the capacities of all the available black start units obtained in the step (3) and the average distance calculated in the step (4), obtaining the restoring force of the power grid after the blackout, and providing a reference basis for the development planning of the power grid.

Power grid restoring force R after heavy power failure_esThe calculation method is

$R_{es}=\frac{P_{black}^{*}}{\stackrel{\‾}{L}}$

Wherein,is a per unit value of the sum of the capacities of all available black start units,is composed ofAndaverage value of (a).

In one embodiment, the present invention is a simulation calculation performed on an IEEE30 node system, and describes a flow of a method for calculating a grid restoration force after a power failure accident. The structure of the IEEE30 node system is shown in fig. 2. According to the method for calculating the power grid restoring force after the blackout, the specific steps of calculating the power grid restoring force after the blackout accident of the IEEE30 node system are as follows:

s1: and identifying the specific state of the system, acquiring data used for calculation, and establishing a weighted network connection matrix corresponding to the system.

Identifying the state of the system refers to performing availability diagnosis on all power generation, transmission and transformation equipment in the system, namely identifying and judging the state of the equipment, and screening out the equipment in a fault state or a maintenance state (equipment unavailable in a recovery process); the data required for the calculation are: the number and the unit capacity of the black start unit and the unit to be recovered in the system, the connection relation of the available power transmission lines in the system and the corresponding line parameters.

Calculating line l_ijPer unit value x of line reactance of_ijTime, reference value S_BTaken as 100MVA, U_BAnd taking the standard voltage of each voltage class.

In the IEEE30 node system, the unit on node 1 is a black start unit, and the capacity is 50 MW. The units on the nodes 2, 13, 22, 23 and 27 are to-be-recovered units, and the unit capacities are 60MW, 25MW, 45MW, 50MW and 55MW respectively. The voltage class of the IEEE30 node system is 220 kV.

In this step, after a power failure accident occurs to the IEEE30 node system, the availability of various devices in the power grid is diagnosed, and the following conclusion is drawn: various devices in the IEEE30 node system may be available for use during the recovery process. And acquiring the number and the unit capacity of the black start unit and the unit to be recovered in the system, the connection relation of the power transmission lines in the system and corresponding line parameters, and calculating the per unit value of each line reactance. And establishing a connection matrix M corresponding to the IEEE30 node system according to the system topology of the IEEE30 node and the calculated per unit value of each line reactance.

S2: selecting available black start units in the system, and calculating the sum of the capacities of all the black start units and corresponding per unit values;

in the black start phase, the black start unit available in the system is started first. And after the black start unit is successfully started, providing required starting power for the rest units without self-starting capability to restart the grid connection. The capacity of the black start unit represents the capability of rapidly recovering after a large-area power failure accident occurs to the system, and can be used as an important index for reflecting the power grid restoring force.

In the step, only the unit on the node 1 in the IEEE30 node system is a black start unit, and the sum P of the capacities of the black start units in the system is easy to calculate_blackIs 50MW, corresponding to a per unit value of

$P_{black}^{*}=\frac{P_{black}}{S_B}=\frac{50}{100}=0.5$

S3: and calculating the average shortest distance from each unit to be recovered to the black start unit and the average shortest distance from the load node to each unit node in the system, and calculating the average distance between the load node and each unit node.

According to a connection matrix M corresponding to an IEEE30 node system, firstly, the shortest distance from nodes 2, 13, 22, 23 and 27 where a unit to be recovered is located to a node 1 where a black start unit is located is calculated. The shortest path algorithm comprises the following calculation steps:

1. during initial calculation, the set S only contains a node 1, the set U contains all nodes except the node 1, and for any point x in the set U, D [ x ] is the distance from the node 1 to the point x;

2. the point x with the minimum D [ x ] in the set U is a node 2, and the node 2 is moved from the set U to the set S;

3. for any node y in the remaining nodes of the set U, if there is D [ y [ ]]>D[x]+M_xyThen the distance D [ y ] from the node 1 to the point y]Is set as D [ x ]]+M_xy；

4. Repeating the step 2 and the step 3 until all the nodes in the set U are moved to the set S;

5. the shortest distances from the nodes 2, 13, 22, 23 and 27 to the node 1 where the black start unit is located are D2, D13, D22, D23 and D27.

Average shortest distance from unit to be recovered to black start unit on nodes 2, 13, 22, 23 and 27The calculation formula is as follows:

$\stackrel{\‾}{L_S}=\frac{\underset{i=1}{\overset{5}{\Σ}}{L}_{Si}}{5}$

L_Si＝Dis[i]

the shortest distance path from the unit to be recovered on the node 2 to the black start unit on the node 1 is as follows: 1-2, and the shortest distance is 0.0575.

The shortest distance path from the unit to be recovered on the node 13 to the black start unit on the node 1 is as follows: 1-3, 3-4, 4-12, 12-13, and its shortest distance is 0.6191.

The shortest distance path from the unit to be recovered on the node 22 to the black start unit on the node 1 is as follows: 1-2, 2-6, 6-9, 9-10, 10-21, 21-22, and the shortest distance is 0.6503.

The shortest distance path from the unit to be recovered on the node 23 to the black start unit on the node 1 is as follows: 1-3, 3-4, 4-12, 12-15, 15-23, and the shortest distance is 0.8115.

The shortest distance path from the unit to be recovered on the node 27 to the black start unit on the node 1 is as follows: 1-2, 2-6, 6-28, 28-27, and its shortest distance is 0.6897.

Average shortest distance from unit to be recovered to black start unit on nodes 2, 13, 22, 23 and 27Is 0.5656.

Load nodes can be divided into two categories: the first type is nodes included in the shortest path from node 2, 13, 22, 23 and 27 to node 1, and the total included nodes are: 3. 4, 6, 9, 10, 15, 21, 28.

The second type is a residual load node, and the total contained nodes are as follows: 5. 7, 8, 11, 14, 16, 17, 18, 19, 20, 24, 25, 26, 29, 30. When the shortest distance from the second type node to each unit is calculated, the lines 1-2, 1-3, 3-4, 4-12, 12-13, 2-6, 6-9, 9-10, 10-21, 21-22, 12-15, 15-23, 2-6, 6-28, 28-27 and the nodes connected with the lines are clustered into a point 1, and the shortest distance from the second type node to each unit node is the shortest distance to the clustered point 1. The shortest distance from the second class stage to each unit node is calculated by using the shortest path algorithm and is shown in table 1.

TABLE 1 shortest distance from the second type node to each unit node

Node number	Shortest distance	Node number	Shortest distance
				5	0.1980	19	0.2770
7	0.0820	20	0.2090
				8	0.0420	24	0.1790
11	0.2080	25	0.2087
				14	0.1997	26	0.5887
16	0.1987	29	0.4153
				17	0.0845	30	0.6027
18	0.2185

Average shortest distance from load node to each unit nodeIs 0.2475. Therefore, it isAndaverage value of (2)Is composed of

$\stackrel{\‾}{L}=\frac{\stackrel{\‾}{L_S}+\stackrel{\‾}{L_{ld}}}{2}=0.4065$

S4: and taking the quotient of the per unit value of the sum of the capacities of the black start unit and the average distance in the S3 as a method for quantitatively calculating the recovery force of the power grid after the blackout.

Power grid restoring force R after heavy power failure_esThe calculation method is

$R_{es}=\frac{P_{black}^{*}}{\stackrel{\‾}{L}}$

$R_{es}=\frac{0.5}{0.4065}=1.23$

The power grid resilience of the IEEE30 node system after a blackout is 1.23.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.

Claims (10)

1. A method for calculating a power grid recovery force after a blackout is characterized by comprising the following steps:

(1) the method comprises the steps that availability diagnosis is conducted on all power generation, transmission and transformation equipment in a system, and the number of black-start units and units to be recovered in the system and the corresponding unit capacity, the connection relation of available power transmission lines in the system and corresponding line parameters are obtained;

(2) establishing a weighted network connection matrix corresponding to the system according to the acquired data;

(3) screening out available black start units in the system, and calculating the sum of the capacities of all the available black start units and corresponding per unit values;

(4) calculating the average shortest distance from each unit to be recovered to the black start unit and the average shortest distance from the load node to each unit node in the system, and calculating the average distance between the two average shortest distances;

(5) and (4) according to the per unit value of the sum of the capacities of all the available black start units obtained in the step (3) and the average distance calculated in the step (4), obtaining the restoring force of the power grid after the blackout, and providing a reference basis for the development planning of the power grid.

2. The method for calculating the grid restoration force after blackout according to claim 1, wherein in the step (1), the method for diagnosing the availability of all the power generation, transmission and transformation equipment in the system comprises the following steps:

and identifying and judging the operating states of all the power generation, transmission and transformation equipment in the system, and screening out the equipment in a fault state or a maintenance state, namely the equipment which is unavailable in the recovery process.

3. The method according to claim 1, wherein in the step (2), when the weighted network connection matrix M corresponding to the system is established, M is a square matrix, and the number of rows and columns is equal to the number of available power plant and substation nodes in the system;

when available transmission line l exists between node i and node j in system_ijWhen it is set up, the line l_ijPer unit value of line reactance of x_ijWhose corresponding element in the connection matrix M is M_ijAnd has M_ij＝M_ji＝x_ij(ii) a On the contrary, if no available transmission line exists between the node i and the node j in the system, M is used for judging whether the available transmission line exists between the node i and the node j_ij＝M_ji＝∞。

4. The method for calculating the grid restoration force after the blackout according to claim 1, wherein in the step (3), the average shortest distance from each unit to be restored to the black-start unit in the system is determined according to the minimum value of the shortest distance from each unit to be restored to each black-start unit.

5. The method according to claim 4, wherein the shortest distance Dis between the unit i to be recovered and the black start unit j is calculated_ijIn the process, a node where a black start unit j is located is taken as a source point S, a node where a unit i to be recovered is located is taken as a target node t, and nodes in a weighting network connection matrix M are divided into two types, namely a set S and a set U: the set S is a set of target nodes which have already found the shortest path to the source point S, and the set U is a set of target nodes which have not calculated the shortest path to the source point S.

6. The method as claimed in claim 5, wherein the shortest distance Dis between the unit i to be recovered and the black start unit j is calculated by using the shortest path method_ijThe specific method comprises the following steps:

1) during initial calculation, the set S only contains the source point S, the set U contains all nodes except the source point S, and any point x, D [ x ] in the set U]Is the distance from the source point s to the point x, i.e. the value M of the corresponding element of the line between the source point s and the node x in the connection matrix M_sx；

2) Selecting a point x with the minimum D [ x ] from the set U, and then moving the point x from the set U to the set S;

3) for any node y in the remaining nodes of the set U, if there is D [ y [ ]]>D[x]+M_xyThen the distance D [ y ] from the source point s to the point y]Is set as D [ x ]]+M_xyWherein M is_xyThe numerical value of the corresponding element of the line between the node x and the node y in the connection matrix M;

4) selecting a point y with the minimum D [ y ] from the rest nodes, and then moving the point y from the set U to the set S;

5) repeating the step 3) and the step 4) until all the nodes in the set U are moved to the set S;

6) the shortest distance from the source point s to the target node t is D [ t ].

7. The method for calculating the grid restoration force after the blackout as claimed in claim 1, wherein in the step (4), the average shortest distance from the load node to each unit node is determined according to the minimum value of the shortest distances from the unit i to be restored to all the unit nodes.

8. The method for calculating the grid restoration force after the blackout as claimed in claim 7, wherein when the average shortest distance from the load node to each unit node is calculated, the load node is divided into two types: the load nodes are contained in the recovery paths corresponding to the minimum value of the shortest distance from each unit to be recovered to each black-start unit; the other class is not included in the load nodes in the path;

and clustering the nodes contained in the recovery paths corresponding to the minimum value of the shortest distance from each unit to be recovered to each black-start unit.

9. The method as claimed in claim 7, wherein the shortest distance between the unit i to be recovered and all the unit nodes is calculated by using a shortest path method.

10. The method for calculating the grid restoration force after blackout as claimed in claim 1, wherein in the step (5), the grid restoration force after blackout is: and (4) the quotient of the per unit value of the sum of the capacities of all the available black start units and the average distance calculated in the step (4).