CN115714377A - Online identification method and system for key power transmission section of power grid and storage medium - Google Patents

Abstract

The invention discloses a method, a system and a storage medium for online identification of a key power transmission section of a power grid, which comprises the steps of respectively calculating the electrical betweenness of each line in each power supply area contained in the power grid as importance weight of the line based on a line electrical betweenness algorithm; screening out the lines with the number of electrical mediators larger than a set threshold value in each power supply area as initial sections of each power supply area; and obtaining the key sections of each power supply area based on each initial section by combining a preset line screening method. The method can effectively identify the important power transmission lines in the current power grid and obtain the power transmission section in the critical position.

Description

Online identification method and system for key power transmission section of power grid and storage medium

Technical Field

The invention belongs to the technical field of electric power system dispatching automation, and particularly relates to a method and a system for identifying a key power transmission section of a power grid on line based on a power distribution betweenness and a storage medium.

Background

With the expansion of the scale of the power grid and the access of new energy, the operation mode of the power grid is increasingly changeable, particularly with the access of large-scale intermittent new energy, the randomness of the power grid tide mode is remarkably increased, and the safety characteristics of the power grid tide mode can be frequently changed. The traditional transmission section is obtained by a power grid operation expert through off-line analysis and manual selection. Due to the limitation of human computing power, the manually found section usually only reflects weak links of the power grid in extreme operation modes, and all potential weak operation modes cannot be dynamically identified. Therefore, the traditional method for manually finding the section of the power grid cannot adapt to the rapid change of the operation mode of the power grid, the omission of the key section can be caused, even the safe and stable operation of the power grid is endangered, the formulation of the limit of the key section is too conservative, and the high requirements of the intelligent and fine operation of the modern power grid are difficult to meet.

Disclosure of Invention

Aiming at the problems, the invention provides a method, a device and a system for identifying the key power transmission section of the power grid on line based on the electrical medium number, which can effectively identify the important power transmission line in the current power grid and obtain the power transmission section in the key position.

In order to achieve the technical purpose and achieve the technical effects, the invention is realized by the following technical scheme:

in a first aspect, the invention provides an online identification method for a key power transmission section of a power grid, which comprises the following steps:

respectively calculating the electric betweenness number of each line in each power supply area contained in the power grid as the importance weight of the line based on a line electric betweenness algorithm;

screening out the lines with the number of electrical mediators larger than a set threshold value in each power supply area as initial sections of each power supply area;

and based on each initial section, combining a preset line screening method to obtain the key sections of each power supply area.

Optionally, each supply region is obtained by:

based on the power grid operation mode data, carrying out full-network structure topology on the power grid to obtain a power supply path between the nodes of the power grid equipment;

and dividing the power grid into a plurality of power supply areas according to the power supply path and the equipment voltage grade after the topology and the principle that the equipment voltage grade is smaller than the preset voltage grade and the power supply path exists between the equipment.

Optionally, the obtaining the key sections of the power supply regions based on the initial sections by combining a preset line screening method includes:

and aiming at each power supply area, sequentially setting one line in the initial section to be in a fault state, recalculating the power flow of the power grid, calculating the electrical medians of all other lines in the power supply area where the line in the fault state is located based on the calculation result of the power flow of the power grid, screening out the lines with the electrical medians larger than a set threshold value, adding the lines into a line fault set, and finally combining the line fault set and the initial section into a key section.

Optionally, the method for online identification of the key power transmission section of the power grid further includes:

and aiming at each power supply area, judging the attribute of each line node based on the power inflow and outflow direction of each line node, and carrying out single-loop processing on the double-loop lines.

Optionally, after the step of recalculating the grid power flow, the method further includes:

according to the power grid operation mode data after the power grid load flow calculation, carrying out full-network structure topology on the power grid to obtain full-network structure topology after fault setting; comparing the topology of the whole network structure after the fault setting with the topology of the whole network structure before the fault setting, and if the electric island is disconnected or partial node loss points are caused, taking the line in the fault state as an independent key section.

Optionally, the calculation formula of the electrical permittivity is:

I ^ij (m,n)＝I ⁱ (m,n)-I ^j (m,n)

wherein, B _e (m, n) is the electrical permittivity of the line (m, n), I ^ij (m, n) is a unit current element injected between a power generation-load node pair (i, j) in a power supply area where the line (m, n) is locatedThe resulting current on the line (m, n); w _i Is the actual output of the power generation node i, W _j G is the actual load capacity of the load node j, G is the power generation node set of the power grid, and L is the load node set of the power grid; i is ⁱ (m,n)、I ^j (m, n) are currents induced on the lines (m, n) when the unit current element is injected at the power generation node i and the load node j, respectively;

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the generating node i _mn Is the admittance of the line (m, n),

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the load node j _mn Is the admittance of the line (m, n),

R _mn is the resistance of the line (m, n); x _mn Is the reactance of the line (m, n).

Optionally, the

Are calculated by the following steps:

calculating the voltage of each node caused by injecting unit current elements into a power generation node i by using a node voltage calculation formula, wherein the node voltage calculation formula is as follows:

factorizing an admittance matrix Y to obtain Y = LDU, wherein L is a lower triangular matrix, D is a diagonal matrix, and U is an upper triangular matrix;

at the node voltmeterSimultaneous left and right multiplication of formula by Y ^-1 Obtaining:

wherein N is the total number of line nodes, e _A The unit current element is injected at the power generation node i or the load node j, and A is the power generation node i or the load node j.

In a second aspect, the present invention provides an online identification system for a key power transmission section of a power grid, including:

the electric medium number calculation module is configured to be used for calculating the electric medium number of each line in each power supply area contained in the power grid as a line importance weight based on a line electric medium number algorithm;

the initial section construction module is configured to screen out lines with the number of electrical mediators larger than a set threshold in each power supply area as initial sections of each power supply area;

and the key section construction module is configured to obtain the key sections of the power supply areas based on the initial sections by combining a preset line screening method.

Optionally, the system for online identification of the key power transmission section of the power grid further includes: a power supply area obtaining module including:

the topology unit is configured to perform full-network structure topology on the power grid based on the power grid operation mode data and acquire power supply paths among the nodes of the power grid equipment;

and the partitioning unit is configured to partition the power grid into a plurality of power supply areas according to the power supply path and the device voltage level after the topology, on the basis that the device voltage level is smaller than a preset voltage level and the power supply path exists between the devices.

Optionally, the obtaining the key sections of the power supply regions based on the initial sections by combining a preset line screening method includes:

and aiming at each power supply area, sequentially setting one line in the initial section to be in a fault state, recalculating the power flow of the power grid, calculating the electrical medians of all other lines in the power supply area where the line in the fault state is located based on the calculation result of the power flow of the power grid, screening out the lines with the electrical medians larger than a set threshold value, adding the lines into a line fault set, and finally combining the line fault set and the initial section into a key section.

Optionally, after the step of recalculating the grid power flow, the method further includes:

and performing full-network structure topology on the power grid according to the power grid operation mode data after the load flow calculation to obtain full-network structure topology after the fault setting, comparing the full-network structure topology after the fault setting with the full-network structure topology before the fault setting, and taking the line in the fault state as an independent key section if the power grid has electric island disconnection or causes partial node failure points.

Optionally, the calculation formula of the electrical permittivity is:

I ^ij (m,n)＝I ⁱ (m,n)-I ^j (m,n)

wherein, B _e (m, n) is the electrical permittivity of the line (m, n), I ^ij (m, n) is the current caused on the line (m, n) after the unit current element is injected between the power generation-load node pair (i, j) in the power supply area where the line (m, n) is located; w _i Is the actual output of the generating node i, W _j The actual load capacity of the load node j is G, G is a power generation node set of the power grid, and L is a load node set of the power grid; i is ⁱ (m,n)、I ^j (m, n) are respectively at the time of injecting unit current element into the power generation node i and the load node jThe current induced on the line (m, n);

the voltage, y, caused at the line nodes m, n after the unit current element is injected into the generating node i _mn Is the admittance of the line (m, n),

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the load node j _mn Is the admittance of the line (m, n),

R _mn is the resistance of the line (m, n); x _mn Is the reactance of the line (m, n).

Optionally, the

Are calculated by the following steps:

calculating the voltage of each node caused by injecting a unit current element into a power generation node i by using a node voltage calculation formula, wherein the node voltage calculation formula is as follows:

factorizing an admittance matrix Y to obtain Y = LDU, wherein L is a lower triangular matrix, D is a diagonal matrix, and U is an upper triangular matrix;

multiplying Y simultaneously to the left and right of the node voltage calculation formula ^-1 Obtaining:

wherein N is the total number of line nodes，e _A The unit current element is injected at the power generation node i or the load node j, and A is the power generation node i or the load node j.

A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements a method for online identification of a critical transmission section of a power grid according to any one of the first aspect.

Compared with the prior art, the invention has the beneficial effects that:

the method solves the problems that the traditional method has high difficulty in manually establishing the key section, has low adaptability to the change of the power grid mode, causes omission of the key section and over-conservative transmission limit. The method has the advantages that the operation line is subjected to empowerment by taking the electrical medium number as the line importance weight, the line with high key degree is searched, the power supply characteristics of the power grid in the subareas are considered, the key section is automatically screened out, the analysis efficiency is improved, the important links of the system can be rapidly identified when the randomness of the output of new energy is enhanced, the stability of the key section is dynamically improved, and the operation safety of the power grid is improved.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which:

fig. 1 is a schematic flow chart of a method for identifying a key power transmission section of a power grid on line according to an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of the invention.

The following detailed description of the principles of the invention is provided in connection with the accompanying drawings.

Example 1

The invention provides an online identification method for a key power transmission section of a power grid, which comprises the following steps of:

respectively calculating the electrical betweenness of each line in each power supply area contained in a power grid as line importance weight based on a line electrical betweenness algorithm;

screening out the lines with the electrical betweenness larger than a set threshold in each power supply area as initial sections of each power supply area;

and (3) obtaining the key sections of the power supply areas based on the initial sections by combining a preset line screening method.

In a specific implementation of an embodiment of the invention, each supply area is obtained by:

based on the power grid operation mode data, carrying out full-network structure topology on the power grid to obtain a power supply path between the nodes of the power grid equipment;

according to the power supply path and the equipment voltage grade after the topology, dividing the power grid into a plurality of power supply areas on the basis that the equipment voltage grade is smaller than a preset voltage grade and the power supply path exists between the equipment;

for convenience of analysis, the embodiment of the present invention further provides a simplified processing for each power supply area, specifically: and aiming at each power supply area, judging the attribute of each line node based on the power inflow and outflow direction of each line node, and carrying out single-loop processing on the double-loop lines.

In a specific implementation manner of the embodiment of the present invention, the obtaining, based on each initial section and in combination with a preset line screening method, a key section of each power supply region includes: sequentially setting one line in the initial section to be in a fault state and recalculating the power flow of the power grid aiming at each power supply area; and calculating the electrical betweenness of all other lines in the power supply area of the line in the fault state based on the power grid load flow calculation result, screening out the lines with the electrical betweenness number larger than a set threshold value, adding the lines into a line fault set, and finally combining the line fault set and the initial section into a key section.

In a specific implementation manner of the embodiment of the present invention, the calculation formula of the electrical permittivity is:

I ^ij (m,n)＝I ⁱ (m,n)-I ^j (m,n)

I ⁱ (m,n)＝(U ⁱ (m)-U ^j (n))y _mn

wherein, B _e (m, n) is the electrical permittivity of the line (m, n), I ^ij (m, n) is the current caused on the line (m, n) after the unit current element is injected between the power generation-load node pair (i, j) in the power supply area where the line (m, n) is located; w is a group of _i Is the actual output of the generating node i, W _j The actual load capacity of the load node j is G, G is a power generation node set of the power grid, and L is a load node set of the power grid; i is ⁱ (m,n)、I ^j (m, n) are currents induced on the lines (m, n) when the unit current element is injected into the power generation node i and the load node j, respectively;

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the generating node i _mn Is the admittance of the line (m, n),

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the load node j _mn Is the admittance of the line (m, n),

R _mn is the resistance of the line (m, n); x _mn Is the reactance of the line (m, n).

The above-mentioned

Are calculated by the following steps:

calculating the voltage of each node caused by injecting a unit current element into a power generation node i by using a node voltage calculation formula, wherein the node voltage calculation formula is as follows:

factorizing an admittance matrix Y to obtain Y = LDU, wherein L is a lower triangular matrix, D is a diagonal matrix, and U is an upper triangular matrix;

multiplying Y simultaneously to the left and right of the node voltage calculation formula ^-1 Obtaining:

wherein N is the total number of line nodes, e _A The unit current element is injected at the power generation node i or the load node j, and A is the power generation node i or the load node j.

The method in the examples of the present invention will be described in detail with reference to a specific embodiment. The method for identifying the key power transmission section of the power grid on line in the embodiment of the invention comprises the following steps:

s1: the method comprises the steps that a real-time power dispatching monitoring system based on a target power grid obtains a real-time operation mode of the power grid and real-time measurement data of relevant equipment; the real-time measurement data of the related equipment comprises equipment voltage levels and connection relations of a station, a bus, a line, a main transformer, a circuit breaker and a disconnecting link of the current power grid, remote measurement values (active values and reactive values) of the line and the main transformer and remote signaling values (on/off) of the circuit breaker and the disconnecting link;

s2: carrying out structural topology on the power grid based on the real-time operation mode data of the power grid, and acquiring power supply paths among the nodes of the power grid equipment; according to the power supply path and the equipment voltage grade after the topology, on the principle that the equipment voltage grade is smaller than a preset voltage grade (namely equipment with the same voltage grade is subjected to topology) and the power supply path exists between the equipment, a power grid is divided into a plurality of power supply areas, and simplification processing is performed, wherein the simplification processing specifically comprises the following steps: judging the attribute of each node (power outflow: power generation node; power inflow: load node; power total sum is 0: transmission node) according to the power inflow and outflow direction, carrying out single-loop processing on the double-loop lines and adding the power values;

s3: based on a circuit electrical medium number algorithm, calculating the electrical medium number of each circuit in each power supply area as a circuit importance weight, and screening out the circuits with the electrical medium numbers larger than a set threshold value in each power supply area as initial sections; the method specifically comprises the following steps:

defining the electrical permittivity of the line (m, n) as B _e (m, n) which is calculated by the formula:

in the formula: i is ^ij (m, n) is the current induced on the line (m, n) after injecting the unit current element between the pair of "generating-load" nodes (i, j) in the power supply area where the line (m, n) is located, W _i Is the actual output of the generating node i, W _j And G is the actual load capacity of the load node j, G is the power generation node set of the power grid, and L is the load node set of the power grid.

According to the superposition of linear circuits, I ^ij (m, n) can be represented as:

I ^ij (m,n)＝I ⁱ (m,n)-I ^j (m,n) (2)

in the formula I ⁱ (m,n)、I ^j The (m, n) are currents induced in the lines (m, n) when the unit current element is injected into the power generation node i and the load node j, respectively.

And I ⁱ (m,n)、I ^j (m, n) can be represented as:

I ⁱ (m,n)、I ^j (m, n) are respectively injecting sheets at a power generation node i and a load node jThe current induced on the line (m, n) when the current cell is in place;

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the generating node i _mn Is the admittance of the line (m, n),

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the load node j _mn Is the admittance of the line (m, n).

For the power grid model with N line nodes, a power generation node i can be selected as a reference node, a reduced order admittance matrix Y (NxN) is obtained according to a node voltage equation, and a unit current element e is injected into the power generation node i _i The resulting voltage at each node can be represented as YU ⁱ ＝e ⁱ Namely:

in the formula:

for ease of calculation, the admittance matrix Y (N × N) may be factorized, i.e., Y = LDU, where L is the lower triangular matrix, D is the diagonal matrix, and U is the upper triangular matrix, and further multiplying equation (4) simultaneously from left to right by Y ^-1 The conversion can be obtained as:

by solving the above equation, one can obtain

Calculate out with the same principle

And

in the practical application process, the voltage of each node of the whole network caused by injecting unit current elements into the power generation node and the load node is calculated firstly, and then the current value I of each line of the whole network caused by the unit current elements can be obtained _(m,n) ＝y _mn (U _m -U _n ) (ii) a Then, the current values of all lines caused by all 'power generation-load' node pairs are calculated in sequence, and the power weight of 'power generator-load' is combined

Calculating the electrical dielectric coefficient B of the circuit according to the formula (1) _e (m, n) and screening for B _e (m,n)>K _min Is an initial section of _min The betweenness threshold value is artificially set.

S4: based on each initial section, combining a preset line screening method to obtain a key section of each power supply area; the method for obtaining the key sections of the power supply areas based on the initial sections by combining a preset line screening method comprises the following steps: setting one line in the initial section to be in a fault state in sequence aiming at each power supply area, and recalculating the power flow of the power grid; and calculating the electrical betweenness of all other lines in the power supply area of the line in the fault state based on the power grid load flow calculation result, screening out the lines with the electrical betweenness number larger than a set threshold value, adding the lines into a line fault set, and finally combining the line fault set and the initial section into a key section. Specifically, the method comprises the following steps:

setting a fault of one line K according to the initial section obtained in the step S3, recalculating the flow of the whole network to obtain a new power grid state, and repeating the steps S2 and S3 to calculate that the number of the electric medium is more than K _min And (4) forming a key section by the line fault set K and the initial section.

Example 2

Based on example 1, the inventive example differs from example 1 in that: after the step of recalculating the grid power flow, the method further comprises the following steps:

according to the power grid operation mode data after the power grid load flow calculation, carrying out full-network structure topology on the power grid to obtain full-network structure topology after the fault is set; comparing the full-network topology after the fault setting with the full-network topology before the fault setting, and if the electric island disconnection or partial node missing point is caused in the power grid, taking the line in the fault state as an independent key section.

Other parts of this embodiment are the same as those of the above embodiment, and are not described again here.

Example 3

Based on the same inventive concept as embodiment 1, the embodiment of the present invention provides an online identification system for a key power transmission section of a power grid, including:

the electric medium number calculation module is configured to be used for calculating the electric medium number of each line in each power supply area contained in the power grid as a line importance weight based on a line electric medium number algorithm;

the initial section construction module is configured to screen out lines with the number of electrical mediators larger than a set threshold in each power supply area as initial sections of each power supply area;

and the key section construction module is configured to obtain key sections of the power supply areas based on the initial sections by combining a preset line screening method.

In a specific implementation manner of the embodiment of the present invention, the obtaining, based on each initial section and in combination with a preset line screening method, a key section of each power supply region includes: sequentially setting one line in the initial section to be in a fault state and recalculating the power flow of the power grid aiming at each power supply area; and calculating the electrical betweenness of all other lines in the power supply area of the line in the fault state based on the power grid load flow calculation result, screening out the lines with the electrical betweenness number larger than a set threshold value, adding the lines into a line fault set, and finally combining the line fault set and the initial section into a key section.

In a specific implementation manner of the embodiment of the present invention, the system for online identifying a key power transmission section of a power grid further includes: a power supply area obtaining module including:

the topology unit is configured to perform full-network structure topology on the power grid based on the power grid operation mode data and acquire power supply paths among the nodes of the power grid equipment;

and the partitioning unit is configured to partition the power grid into a plurality of power supply areas according to the power supply path and the device voltage level after the topology, on the basis that the device voltage level is smaller than a preset voltage level and the power supply path exists between the devices.

In a specific implementation manner of the embodiment of the present invention, the method for online identifying a key power transmission section of a power grid further includes:

and judging the attribute of each line node based on the power inflow and outflow direction of each line node for each power supply area, and carrying out single-loop processing on the double-loop.

In a specific implementation manner of the embodiment of the present invention, the calculation formula of the electrical permittivity is:

I ^ij (m,n)＝I ⁱ (m,n)-I ^j (m,n)

I ⁱ (m,n)＝(U ⁱ (m)-U ^j (n))y _mn

wherein, B _e (m, n) is the electrical permittivity of the line (m, n), I ^ij (m, n) is the current caused on the line (m, n) after the unit current element is injected between the power generation-load node pair (i, j) in the area where the line (m, n) is located; w _i Is the actual output of the generating node i, W _j The actual load capacity of the load node j is G, G is a power generation node set of the power grid, and L is a load node set of the power grid; i is ⁱ (m,n)、I ^j (m, n) are respectively led up on the line (m, n) when unit current elements are injected into the power generation node i and the load node jThe current of the capacitor;

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the generating node i _mn Is the admittance of the line (m, n),

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the load node j _mn Is the admittance of the line (m, n),

R _mn is the resistance of the line (m, n); x _mn Is the reactance of the line (m, n).

The above-mentioned

Are calculated by the following steps:

calculating the voltage of each node caused by injecting a unit current element into a power generation node i by using a node voltage calculation formula, wherein the node voltage calculation formula is as follows:

factorizing an admittance matrix Y to obtain Y = LDU, wherein L is a lower triangular matrix, D is a diagonal matrix, and U is an upper triangular matrix;

multiplying Y simultaneously to the left and right of the node voltage calculation formula ^-1 And obtaining:

wherein N is the total number of line nodes, e _A For generating electric poweri or a load node j, and A is a power generation node i or the load node j.

The method in the examples of the present invention will be described in detail with reference to a specific embodiment. In the implementation process of the power grid key power transmission section online identification system in the embodiment of the invention, the method comprises the following steps:

s1: the method comprises the steps that a real-time power dispatching monitoring system based on a target power grid obtains a real-time operation mode of the power grid and real-time measurement data of relevant equipment; the real-time measurement data of the related equipment comprises equipment voltage levels and connection relations of a station, a bus, a line, a main transformer, a circuit breaker and a disconnecting link of the current power grid, remote measurement values (active values and reactive values) of the line and the main transformer and remote signaling values (on/off) of the circuit breaker and the disconnecting link;

s2: carrying out structural topology on the power grid based on the real-time operation mode data of the power grid, and acquiring power supply paths among the nodes of the power grid equipment; according to the power supply path and the equipment voltage grade after the topology, on the principle that the equipment voltage grade is smaller than a preset voltage grade (namely equipment with the same voltage grade is subjected to topology) and the power supply path exists between the equipment, a power grid is divided into a plurality of power supply areas, and simplification processing is performed, wherein the simplification processing specifically comprises the following steps: judging the attribute of each node according to the power inflow and outflow direction (power outflow: power generation node; power inflow: load node; power sum is 0: transmission node), carrying out single-loop processing on the double-loop lines and adding the power values;

s3: based on a circuit electrical medium number algorithm, calculating the electrical medium number of each circuit in each power supply area as a circuit importance weight, and screening out the circuits with the electrical medium numbers larger than a set threshold value in each power supply area as initial sections; the method specifically comprises the following steps:

defining the electrical permittivity of the line (m, n) as B _e (m, n) which is calculated by the formula:

in the formula: i is ^ij (m, n) is the power supply of the line (m, n)Current, W, induced on line (m, n) after unit current element is injected between "generation-load" node pair (i, j) in area _i Is the actual output of the generating node i, W _j And G is the actual load capacity of the load node j, G is the power generation node set of the power grid, and L is the load node set of the power grid.

According to the superposition of linear circuits, I ^ij (m, n) can be represented as:

I ^ij (m,n)＝I ⁱ (m,n)-I ^j (m,n) (2)

in the formula I ⁱ (m,n)、I ^j (m, n) are currents induced on the lines (m, n) when the unit current element is injected into the power generation node i and the load node j, respectively.

And I ⁱ (m,n)、I ^j (m, n) can be represented as:

I ⁱ (m,n)、I ^j (m, n) are currents induced on the lines (m, n) when the unit current element is injected at the power generation node i and the load node j, respectively;

the voltage, y, caused at the line nodes m, n after the unit current element is injected into the generating node i _mn Is the admittance of the line (m, n),

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the load node j _mn Is the admittance of the line (m, n).

For the power grid model with N line nodes, a power generation node i can be selected as a reference node, a reduced order admittance matrix Y (NxN) is obtained according to a node voltage equation, and a unit current element e is injected into the power generation node i _i The resulting voltage at each node can be represented as YU ⁱ ＝e ⁱ Namely:

in the formula:

for ease of calculation, the admittance matrix Y (N × N) may be factorized, i.e., Y = LDU, where L is the lower triangular matrix, D is the diagonal matrix, and U is the upper triangular matrix, and further multiplying equation (4) by Y simultaneously from left to right ^-1 The conversion can be obtained as:

by solving the above equation, one can obtain

Calculate out with the same principle

And

in the practical application process, the voltage of each node of the whole network caused by injecting unit current elements into the power generation node and the load node is calculated, and then the current value I of each line of the whole network caused by the unit current elements can be obtained _(m,n) ＝y _mn (U _m -U _n ) (ii) a Then, the current values of all lines caused by all 'power generation-load' node pairs are calculated in sequence, and the power weight of 'power generator-load' is combined

Calculating the electrical dielectric coefficient B of the circuit according to the formula (1) _e (m, n) and screening for B _e (m,n)>K _min Is an initial section of _min The betweenness threshold value is set manually.

S4: based on each initial section, combining a preset line screening method to obtain a key section of each power supply area; the method for obtaining the key sections of the power supply areas based on the initial sections by combining a preset line screening method comprises the following steps: setting one line in the initial section to be in a fault state in sequence aiming at each power supply area, and recalculating the power flow of the power grid; and calculating the electrical betweenness of all other lines in the power supply area of the line in the fault state based on the power grid load flow calculation result, screening out the lines with the electrical betweenness number larger than a set threshold value, adding the lines into a line fault set, and finally combining the line fault set and the initial section into a key section. Specifically, the method comprises the following steps:

setting a fault of one line K according to the initial section obtained in the step S3, recalculating the flow of the whole network to obtain a new power grid state, repeating the steps S2 and S3 to calculate that the electrical medium number is more than K _min And (4) forming a key section by the line fault set K and the initial section.

Example 4

Based on example 3, the inventive example differs from example 3 in that: after the step of recalculating the grid power flow, the method further comprises the following steps:

according to the power grid operation mode data after the power grid load flow calculation, carrying out full-network structure topology on the power grid to obtain full-network structure topology after the fault is set; comparing the full-network topology after the fault setting with the full-network topology before the fault setting, and if the electric island disconnection exists in the power grid or partial node failure is caused, taking the line in the fault state as an independent key section.

Other parts of this embodiment are the same as those of the above embodiment, and are not described again here.

Example 5

Based on the same inventive concept as embodiment 1, an embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the method for online identification of a critical transmission section of a power grid according to any one of embodiment 1 or embodiment 2.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (8)

1. A method for online identification of a key power transmission section of a power grid is characterized by comprising the following steps:

respectively calculating the electric betweenness of each line in each power supply area contained in the power grid as line importance weight based on a line electric betweenness algorithm;

screening out the lines with the number of electrical mediators larger than a set threshold value in each power supply area as initial sections of each power supply area;

and obtaining the key sections of each power supply area based on each initial section by combining a preset line screening method.

2. The method for on-line identification of the key power transmission section of the power grid according to claim 1, characterized by comprising the following steps: each power supply region is obtained by the following steps:

based on the power grid operation mode data, carrying out full-network structure topology on the power grid to obtain a power supply path between the nodes of the power grid equipment; and dividing the power grid into a plurality of power supply areas according to the power supply path and the equipment voltage grade after the topology and the principle that the equipment voltage grade is smaller than the preset voltage grade and the power supply path exists between the equipment.

3. The method for on-line identification of the key power transmission section of the power grid according to claim 1, characterized by comprising the following steps: the step of obtaining the key sections of the power supply areas based on the initial sections by combining a preset line screening method comprises the following steps: setting one line in the initial section to be in a fault state in sequence aiming at each power supply area, and recalculating the power flow of the power grid; and calculating the electrical betweenness of all other lines in the power supply area of the line in the fault state based on the power grid load flow calculation result, screening out the lines with the electrical betweenness number larger than a set threshold value, adding the lines into a line fault set, and finally combining the line fault set and the initial section into a key section.

4. The method for on-line identification of key transmission sections of the power grid according to claim 3, wherein after the step of recalculating the power flow of the power grid, the method further comprises:

according to the power grid operation mode data after the power grid load flow calculation, carrying out full-network structure topology on the power grid to obtain full-network structure topology after the fault is set; comparing the full-network topology after the fault setting with the full-network topology before the fault setting, and if the electric island disconnection exists in the power grid or partial node failure is caused, taking the line in the fault state as an independent key section.

5. The method for on-line identification of the key power transmission section of the power grid according to claim 1, characterized by comprising the following steps: the calculation formula of the electrical permittivity is as follows:

I ^ij (m,n)＝I ⁱ (m,n)-I ^j (m,n)

wherein, B _e (m, n) is the electrical permittivity of the line (m, n), I ^ij (m, n) is the current caused on the line (m, n) after the unit current element is injected between the power generation-load node pair (i, j) in the power supply area where the line (m, n) is located; w _i Is the actual output of the generating node i, W _j The actual load capacity of the load node j is G, G is a power generation node set of the power grid, and L is a load node set of the power grid; i is ⁱ (m,n)、I ^j (m, n) are currents induced on the lines (m, n) when the unit current element is injected at the power generation node i and the load node j, respectively;

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the generating node i _mn Is the admittance of the line (m, n),

for the voltage, y, induced at the line nodes m, n after the unit current element is injected at the load node j _mn Is the admittance of the line (m, n),

R _mn is the resistance of the line (m, n); x _mn Is the reactance of the line (m, n).

6. The method for on-line identification of the key power transmission section of the power grid according to claim 5, characterized by comprising the following steps: the above-mentioned

Are calculated by the following steps:

calculating the voltage of each node caused by injecting unit current elements into a power generation node i by using a node voltage calculation formula, wherein the node voltage calculation formula is as follows:

factorizing an admittance matrix Y to obtain Y = LDU, wherein L is a lower triangular matrix, D is a diagonal matrix, and U is an upper triangular matrix;

multiplying Y simultaneously to the left and right of the node voltage calculation formula ^-1 Obtaining:

wherein N is the total number of line nodes, e _A The unit current element is injected at the power generation node i or the load node j, and A is the power generation node i or the load node j.

7. The utility model provides a key transmission of electricity section online identification system of electric wire netting which characterized in that includes:

the power supply system comprises a power supply area calculation module, a power distribution medium calculation module and a power distribution medium calculation module, wherein the power supply area calculation module is configured to be used for calculating the power distribution medium of each line in each power supply area contained in a power grid based on a line power distribution medium algorithm as a line importance weight;

the initial section construction module is configured to screen out lines with the number of electrical mediators larger than a set threshold in each power supply area as initial sections of each power supply area;

and the key section construction module is configured to obtain the key sections of the power supply areas based on the initial sections by combining a preset line screening method.

8. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out a method for online identification of a critical transmission section of a power grid according to any one of claims 1 to 6.

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