CN113610371A - Toughness-based freezing disaster power grid weak link evaluation method and device - Google Patents
Toughness-based freezing disaster power grid weak link evaluation method and device Download PDFInfo
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Abstract
The invention provides a toughness-based freezing disaster power grid weak link evaluation method and device, wherein the method comprises the following steps: determining the line fault probability under ice disasters according to the weather conditions; calculating a power grid evaluation toughness index according to the fault probabilities of the multiple lines; calculating an element-level toughness index under ice disasters according to the power grid evaluation toughness index; and determining the prevention priority according to the element-level toughness index under the ice disaster. To reflect the degree of contribution of different line faults to the system toughness. Can provide theoretical guidance for the working personnel to carry out pre-disaster prevention and emergency deicing work. And the damage of ice disasters to the power grid is reduced.
Description
Technical Field
The invention belongs to the technical field of power grid risk assessment, and particularly relates to a toughness-based method and device for assessing weak links of a freezing disaster power grid.
Background
The safe operation of the power grid is concerned with national economic life, and along with the development of the power industry, most power grids have high reliability, so that the power grids can be ensured to stably and reliably operate under the conventional condition. However, with frequent extreme weather events, the lines widely exposed to the external environment are exposed to the problem of insufficient preparation in the face of these High-Probability Low performance (HILP) disasters.
The ice disaster belongs to one of the extreme natural disasters which are frequent and cause great loss, and brings serious damage to the power grid worldwide. Severe icing events, such as those occurring in norway in 1961, resulted in line icing thicknesses in excess of 1400 mm. Ice and snow disasters in Ontario and Quebec provinces in the east of canada and in the northeast of the united states in 1998 have led to over 1000 high voltage transmission towers and over 30000 distribution towers being inverted, with economic losses of up to 35 billion dollars. In the end of 2004 to the beginning of 2005, severe rainy and snowy weather attacks Hunan of China, 6 500kV lines are stopped due to ice flashover, and 4 220kV lines are disconnected. The ice and snow disasters in the series warn people, and the ice and snow disasters become a great threat to the safe and stable operation of the power grid. The elements in the power grid are numerous, and multiple faults of the lines are easy to occur under the influence of extreme ice disasters, so that large-area power failure of the power grid is caused. In view of the high dependence of daily production and social services on power supply, the system performance of the power grid in the face of such disasters is reasonably evaluated, and the method has great significance for improving the resistance of the power grid to such disasters.
Disclosure of Invention
In view of the above, the invention aims to provide a toughness-based freezing disaster power grid weak link evaluation method and device, so as to solve the technical problem that the performance of a power grid in a freezing disaster is not reasonably evaluated in the prior art.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
on one hand, the embodiment of the invention provides a toughness-based freezing disaster power grid weak link evaluation method, which comprises the following steps:
determining the line fault probability under ice disasters according to the weather conditions;
calculating a power grid evaluation toughness index according to the fault probabilities of the multiple lines;
calculating an element-level toughness index under ice disasters according to the power grid evaluation toughness index;
determining a prevention priority according to the element-level toughness index under the ice disaster;
the method for calculating the power grid evaluation toughness index according to the line fault probabilities comprises the following steps:
calculating the toughness index of the power grid under ice disasters by using a state enumeration method based on all lines of the system;
the method for calculating the toughness index of the power grid under the ice disaster based on all lines of the system by using a state enumeration method comprises the following steps:
probability P of s of fault scene calculated based on all lines of systems，
Probability P of s according to the fault scenariosAnd calculating the toughness index of the power grid under the ice disaster by using a state enumeration method.
Further, the probability P of s of the fault scene is calculated based on all lines of the systemsThe method is realized based on the following steps:
in the formula, i is a fault line number in a fault scene s; p is a radical ofiRepresenting the fault probability of the ith line;
correspondingly, the power grid toughness index under ice disaster is calculated by using a state enumeration method according to the probability Ps of the s of the fault scene, and the method is realized by adopting the following mode:
wherein R issysRepresenting a system level toughness index; n represents the number of lines; a represents the set of all lines, Ωk ARepresents a k-th order subset of a; s represents omegak AOne failure of (2); psThe probability of the fault scene s is represented and calculated by a state enumeration method; i issThis indicates the influence of the fault scenario s, i.e., the amount of system load reduction caused by the fault scenario s.
Further, the calculating of the element-level toughness index under ice disaster according to the power grid evaluation toughness index includes:
calculating the toughness index increment of the power grid caused by the fault of any one line;
and calculating the element-level toughness index under the ice disaster based on the power grid toughness index increment caused by any one line fault.
Further, the calculation of the power grid toughness index increment caused by any line fault is realized by adopting the following method:
the grid toughness index increment caused by the mth line fault is expressed as:
wherein R issys|pm0 represents the system toughness index when the mth line is not in fault; rsys|pm1 represents the system toughness index when the mth line has certain faults; smRepresenting a set of all fault scenarios containing the mth line fault; delta IsmFor fault scenarios smThe resulting incremental impact;
correspondingly, the element-level toughness index under ice disaster is calculated based on the power grid toughness index increment caused by any one line fault, and the method is realized by adopting the following mode:
in the formula, pm represents the failure probability of the line m.
Further, the determining the line fault probability under the ice disaster according to the weather condition includes:
line ice wind power load L is calculated based on wind power load and ice force load of lineWI；
According to the ice wind load L of the lineWICalculating the line fault probability p per unit lengthf。。
Further, the ice wind power load L of the line is calculated based on the wind power load and the ice load of the lineWIThe method comprises the following steps:
calculating the ice load L of a line of unit lengthI；
According to the ice force load LICalculating the wind load L of the line of unit lengthW(N/m)；
Calculating ice wind load L of lineWI。
Furthermore, the load L is ice wind power according to the lineWICalculating the line fault per unit length includes the probability pfThe method is realized based on the following steps:
wherein, aWIAnd bWIRespectively a first and a second threshold value (N/m) for the ice wind load.
On the other hand, the embodiment of the invention also provides a toughness-based freezing disaster power grid weak link evaluation device, which comprises the following steps:
the line fault probability determination module is used for determining the line fault probability under ice disasters according to the weather conditions;
the power grid evaluation toughness index calculation module is used for calculating power grid evaluation toughness indexes according to the fault probabilities of the multiple lines;
the ice disaster lower element level toughness index calculation module is used for calculating an ice disaster lower element level toughness index according to the power grid evaluation toughness index;
the priority determining module is used for determining a prevention priority according to the element-level toughness index under the ice disaster;
further, the power grid evaluation toughness index calculation module includes:
the power grid toughness index calculating unit is used for calculating a power grid toughness index under ice disasters based on all lines of the system by using a state enumeration method;
the power grid toughness index calculation unit comprises:
a probability calculation subunit for calculating the probability P of s of the fault scene based on all the lines of the systems，
A power grid toughness index calculation subunit, configured to calculate a probability P of s according to the fault scenariosAnd calculating the toughness index of the power grid under the ice disaster by using a state enumeration method.
Further, the probability calculation subunit is implemented based on the following manner:
in the formula, i is a fault line number in a fault scene s; p is a radical ofiRepresenting the fault probability of the ith line;
correspondingly, the power grid toughness index calculation subunit is realized by adopting the following mode:
wherein R issysRepresenting a system level toughness index; n represents the number of lines; a represents the set of all lines, Ωk ARepresents a k-th order subset of a; s represents omegak AOne failure of (2); psThe probability of the fault scene s is represented and calculated by a state enumeration method; i issThis indicates the influence of the fault scenario s, i.e., the amount of system load reduction caused by the fault scenario s.
Further, the module for calculating the element-level toughness index in ice disaster includes:
the index increment calculating unit is used for calculating the toughness index increment of the power grid caused by the fault of any one line;
and the element-level toughness index calculating unit is used for calculating the element-level toughness index under the ice disaster based on the power grid toughness index increment caused by any one line fault.
Further, the index increment calculating unit is implemented by adopting the following mode:
the grid toughness index increment caused by the mth line fault is expressed as:
wherein R issys|pm0 represents the system toughness index when the mth line is not in fault; rsys|pm1 represents the system toughness index when the mth line has certain faults; smRepresenting a set of all fault scenarios containing the mth line fault; delta IsmFor fault scenarios smThe resulting incremental impact;
correspondingly, the element-level toughness index calculation unit is realized by adopting the following mode:
in the formula, pm represents the failure probability of the line m.
Further, the line fault probability determination module includes:
the line ice wind power load unit is used for calculating a line ice wind power load L based on the wind power load and the ice force load of the lineWI；
A line fault probability calculation unit for calculating the line fault probability according to the ice wind load LWICalculating the line fault probability p per unit lengthf。。
Further, the ice wind load cell of the route includes:
unit ice force loadA load calculating subunit for calculating the ice load L of the line per unit lengthI；
A unit wind load calculating subunit for calculating the load L according to the ice forceICalculating the wind load L of the line of unit lengthW(N/m)；
A line ice wind power load calculating subunit for calculating the line ice wind power load LWI。
Further, the line fault probability calculation unit, probability pfThe method is realized based on the following steps:
wherein, aWIAnd bWIRespectively a first and a second threshold value (N/m) for the ice wind load.
Compared with the prior art, the toughness-based freezing disaster power grid weak link evaluation method and device have the following advantages: according to the toughness-based freezing disaster power grid weak link evaluation method and device, the line fault probability under ice disasters is determined according to weather conditions; calculating a power grid evaluation toughness index according to the fault probabilities of the multiple lines; calculating an element-level toughness index under ice disasters according to the power grid evaluation toughness index; and determining the prevention priority according to the element-level toughness index under the ice disaster. The performance of the power grid in the freezing disaster is reasonably evaluated by acquiring the predicted weather data of a period of time in the future. The fault probability of a single line is considered, load reduction brought by the line is comprehensively considered, and the overall state of the system is favorably known. In order to further locate weak links of the system, an element-level toughness index is defined to reflect the contribution degree of different line faults to the toughness of the system. Can provide theoretical guidance for the working personnel to carry out pre-disaster prevention and emergency deicing work. And the damage of ice disasters to the power grid is reduced.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic flow chart of a toughness-based freezing disaster power grid weak link evaluation method according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a toughness-based evaluation device for weak links of a freezing disaster power grid according to an embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
In the description of the present invention, it is to be understood that the terms "first", "second", and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Example one
Fig. 1 is a schematic flow diagram of a toughness-based freezing disaster power grid weak link evaluation method according to an embodiment of the present invention, and the toughness-based freezing disaster power grid weak link evaluation method according to the embodiment of the present invention is applicable to a situation of evaluating a power grid weak link caused by a freezing disaster, and can be executed by a toughness-based freezing disaster power grid weak link evaluation device. Referring to fig. 1, the toughness-based freezing disaster power grid weak link assessment method includes:
and S110, determining the line fault probability under the ice disaster according to the weather condition.
The concept of "toughness" was first introduced by c.s.colling into the ecosystem of research for discussing the problem of changes in biomass therein. Thereafter, toughness has been gradually expanded for use in various fields such as psychology, social ecology, and economy. In the context of the power grid, ductility is defined as the ability of the grid to withstand abnormal and high impact-low probability events, while recovering quickly from such destructive events, to draw empirical lessons therefrom to adjust its mode of operation and structure to prevent or mitigate the effects of future similar events on the grid.
In the embodiment, the power grid line fault condition caused by ice disaster is evaluated based on the definition of "toughness". Specifically, the weather condition is first acquired. For example, weather data for a future period of time can be obtained through weather forecasts by a weather department.
For example, the determining the probability of the line fault under the ice disaster according to the weather condition may include: line ice wind power load L is calculated based on wind power load and ice force load of lineWI(ii) a . According to the ice wind load L of the lineWICalculating the line fault probability p per unit lengthf。。
In this embodiment, first, the main cause of the fault in the power grid is analyzed under the ice disaster condition, wind and ice are determined as two important influence factors, and the line fault probability is calculated according to the superposition influence of the two important influence factors.
Optionally, the ice wind power load L of the line is calculated based on the wind power load and the ice load of the lineWIThe method comprises the following steps: calculating the ice load L of a line of unit lengthI(ii) a According to the ice force load LICalculating the wind load L of the line of unit lengthW(N/m); calculating ice wind load L of lineWI
Specifically, the ice load L of the line with the bit length can be specifically determined through a line fault probability model under ice disasterI。
The icing calculation model may be specifically expressed as:
in the formula, ReqRepresentsThickness of ice coating (mm), T represents duration hours (h) of freezing rain, pi is 3.14, r represents rainfall rate (mm/h), rhoIAnd ρWRepresents the density of ice and water, respectively, v represents the wind speed (m/s), and W represents the water content in air, as represented by the formula W ═ 0.067 xr0.864And (4) calculating.
Calculating the ice load L of the line with unit length based on the ice coating thicknessI(N/m)：
LI＝9.8×10-3ρIπ(D+Req)Req
Wherein D is the wire diameter (mm).
Wind load L per unit length of lineW(N/m) is as follows:
LW＝CSvg 2(D+2Req)
wherein C is constant coefficient, 6.964 × 10-3S is a span factor, vgIs the wind speed.
Line ice wind power load L under combined action of ice wind powerWI(N/m) is as follows:
and the line fault probability pf of unit length can be calculated based on the statistical probability as follows:
wherein, aWIAnd bWIRespectively a first and a second threshold value (N/m) for the ice wind load.
And S130, calculating the power grid evaluation toughness index according to the fault probabilities of the multiple lines.
In this embodiment, the grid evaluation toughness index may be calculated according to the lengths of all lines in the area, and by combining the line fault probability per unit length calculated in the above steps.
For example, the grid evaluation toughness index may be calculated as follows. In this embodiment, an enumeration method is adopted to calculate the power grid evaluation toughness index. An enumeration of a set is a procedure that lists all members of some finite set of sequences.
In this embodiment, the toughness index of the power grid system may be calculated as follows:
in the formula, RsysRepresenting a system level toughness index; n represents the number of lines; a represents the set of all lines, Ωk ARepresents a k-th order subset of a; s represents omegak AOne failure of (2); psThe probability of the fault scene s is represented and calculated by a state enumeration method; i issThis indicates the influence of the fault scenario s, i.e., the amount of system load reduction caused by the fault scenario s.
Probability P of s for a failure scenariosCalculated by the following method:
in the formula, i is a fault line number in a fault scene s; p is a radical ofiIndicating the probability of failure of the ith line.
Correspondingly, the system-level toughness index under ice disasters can be represented as follows:
in the formula,. DELTA.IsIs the incremental contribution of the fault scenario s.
Through the formula, the system-level toughness index can be improved from static consideration to dynamic consideration, and the influence of a certain line fault on the system-level toughness index is considered.
The ice wind load and the predicted failure probability of the line can be obtained. On the basis, the element-level toughness index of each line can be calculated. According to the definition of the element-level toughness index, the larger the index value of the line is, the higher the possibility that the line brings more toughness loss to the system when the ice disaster comes is represented. By sequencing the toughness indexes of all lines, the prevention priority sequencing of all lines can be obtained, and therefore weak links of the system are positioned.
Illustratively, the element-level toughness indicator may be calculated as follows
The grid toughness index increment caused by the mth line fault is expressed as:
in the formula, Rsys|pm0 represents the system toughness index when the mth line is not in fault; rsys|pm1 represents the system toughness index when the mth line has certain faults; smRepresenting a set of all fault scenarios containing the mth line fault; delta IsmFor fault scenarios smThe resulting increase in influence.
The element-level toughness indexes under ice disasters are represented as follows:
in the formula, pmRepresenting the probability of failure of line m.
Accurately locating the weak link of the system will allow the system operator to prepare in a manner that mitigates the effects of ice damage. For example, repair and recovery personnel will be efficiently dispatched and pre-deployed with the necessary resources to be able to quickly arrive at the failure site to recover the damaged component when repairs can be taken. Or effective precautionary measures are taken on the critical line to reduce the probability of line failure. For example, hydrophobic coating is coated on the line, and ice melting equipment and the like are additionally arranged, so that the ice coating possibility of the line is reduced, and the toughness loss of the system is reduced.
2) Strategy for improving toughness in disaster
Along with the ice coating on the first line, the ice disaster enters the disaster period. In view of the fact that the design of the line generally has certain anti-icing capacity, in the early stage of a disaster, when the icing thickness of the line is far lower than the anti-icing design value of the line, the possibility of faults is basically avoided, and the power grid is completely composed of normal lines. And in the middle and later periods of the disaster, the line fails due to ice coating until the ice coating stops growing, and the ice disaster is ended.
In the period of disaster, in order to improve the toughness of the system, corrective measures can be taken for the normally running lines according to the priority sequence. Corrective action definitions are "activities deployed during natural disasters". In consideration of the severity and uncertainty of ice damage, it is very difficult to perform maintenance work on public facilities, i.e., lines. Under the condition, the more critical non-fault line is deiced to ensure that the non-fault line can normally work in the ice disaster process, and compared with the method for repairing the fault line, the method has practical significance and is easier to implement. Corrective measures are therefore referred to herein as preventive deicing measures.
To achieve this, it is necessary to perform importance evaluation on a normally operating line in advance, obtain a deicing sequence thereof, and continue to use the pre-disaster toughness index to complete the process. Notably, during this process, the meteorological data is changing in real time. As the weather conditions become more severe or lessened, the importance ranking of the lines in the system also changes, requiring the system operator to have adequate awareness of the system status. That is, the system operators should adjust their emergency plans according to the latest meteorological data and implementation of deicing measures, and therefore the deicing prioritization should be updated daily to provide the most real-time and reliable guidance to the relevant workers.
Example two
Fig. 2 is a schematic structural diagram of a toughness-based apparatus for evaluating weak links of a freezing disaster power grid according to a second embodiment of the present invention, and referring to fig. 2, the toughness-based apparatus for evaluating weak links of a freezing disaster power grid includes:
a line fault probability determination module 210, configured to determine a line fault probability in an ice disaster according to a weather condition;
the power grid evaluation toughness index calculation module 220 is used for calculating a power grid evaluation toughness index according to the line fault probabilities;
the under-ice-disaster element-level toughness index calculating module 230 is configured to calculate an under-ice-disaster element-level toughness index according to the power grid evaluation toughness index;
a priority determining module 240, configured to determine a prevention priority according to the element-level toughness index in the ice disaster;
the power grid evaluation toughness index calculation module comprises:
the power grid toughness index calculating unit is used for calculating a power grid toughness index under ice disasters based on all lines of the system by using a state enumeration method;
the power grid toughness index calculation unit comprises:
a probability calculation subunit for calculating the probability P of s of the fault scene based on all the lines of the systems，
A power grid toughness index calculation subunit, configured to calculate a probability P of s according to the fault scenariosAnd calculating the toughness index of the power grid under the ice disaster by using a state enumeration method.
According to the toughness-based freezing disaster power grid weak link evaluation device provided by the embodiment of the invention, the line fault probability under ice disasters is determined according to the weather conditions; calculating a power grid evaluation toughness index according to the fault probabilities of the multiple lines; calculating an element-level toughness index under ice disasters according to the power grid evaluation toughness index; and determining the prevention priority according to the element-level toughness index under the ice disaster. The performance of the power grid in the freezing disaster is reasonably evaluated by acquiring the predicted weather data of a period of time in the future. The fault probability of a single line is considered, load reduction brought by the line is comprehensively considered, and the overall state of the system is favorably known. In order to further locate weak links of the system, an element-level toughness index is defined to reflect the contribution degree of different line faults to the toughness of the system. Can provide theoretical guidance for the working personnel to carry out pre-disaster prevention and emergency deicing work. And the damage of ice disasters to the power grid is reduced.
On the basis of the above embodiment, the power grid evaluation toughness index calculation module includes:
the power grid toughness index calculating unit is used for calculating a power grid toughness index under ice disasters based on all lines of the system by using a state enumeration method;
the power grid toughness index calculation unit comprises:
a probability calculation subunit for calculating the probability P of s of the fault scene based on all the lines of the systems，
On the basis of the above embodiment, the probability calculation subunit is implemented based on the following manner:
in the formula, i is a fault line number in a fault scene s; p is a radical ofiRepresenting the fault probability of the ith line;
correspondingly, the power grid toughness index calculation subunit is realized by adopting the following mode:
wherein R issysRepresenting a system level toughness index; n represents the number of lines; a represents the set of all lines, Ωk ARepresents a k-th order subset of a; s represents omegak AOne failure of (2); psThe probability of the fault scene s is represented and calculated by a state enumeration method; i issThis indicates the influence of the fault scenario s, i.e., the amount of system load reduction caused by the fault scenario s.
On the basis of the above embodiment, the module for calculating the element-level toughness index in ice disaster includes:
the index increment calculating unit is used for calculating the toughness index increment of the power grid caused by the fault of any one line;
and the element-level toughness index calculating unit is used for calculating the element-level toughness index under the ice disaster based on the power grid toughness index increment caused by any one line fault.
On the basis of the above embodiment, the index increment calculating unit is implemented as follows:
the grid toughness index increment caused by the mth line fault is expressed as:
wherein R issys|pm0 represents the system toughness index when the mth line is not in fault; rsys|pm1 represents the system toughness index when the mth line has certain faults; smRepresenting a set of all fault scenarios containing the mth line fault; delta IsmFor fault scenarios smThe resulting incremental impact;
correspondingly, the element-level toughness index calculation unit is realized by adopting the following mode:
in the formula, pm represents the failure probability of the line m.
On the basis of the above embodiment, the line fault probability determining module includes:
the line ice wind power load unit is used for calculating a line ice wind power load L based on the wind power load and the ice force load of the lineWI；
A line fault probability calculation unit for calculating the line fault probability according to the ice wind load LWICalculating the line fault probability p per unit lengthf。。
On the basis of the above embodiment, the ice wind load cell comprises:
a unit ice load calculating subunit for calculating the ice load L of the line with unit lengthI；
Single windA force load calculating subunit for calculating the force load L according to the ice force loadICalculating the wind load L of the line of unit lengthW(N/m)；
A line ice wind power load calculating subunit for calculating the line ice wind power load LWI。
On the basis of the above-described embodiments, the line fault probability calculation unit, probability pfThe method is realized based on the following steps:
wherein, aWIAnd bWIRespectively a first and a second threshold value (N/m) for the ice wind load.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A toughness-based freezing disaster power grid weak link assessment method is characterized by comprising the following steps:
determining the line fault probability under ice disasters according to the weather conditions;
calculating a power grid evaluation toughness index according to the fault probabilities of the multiple lines;
calculating an element-level toughness index under ice disasters according to the power grid evaluation toughness index;
determining a prevention priority according to the element-level toughness index under the ice disaster;
the method for calculating the power grid evaluation toughness index according to the line fault probabilities comprises the following steps:
calculating the toughness index of the power grid under ice disasters by using a state enumeration method based on all lines of the system;
the method for calculating the toughness index of the power grid under the ice disaster based on all lines of the system by using a state enumeration method comprises the following steps:
probability P of s of fault scene calculated based on all lines of systems，
Probability P of s according to the fault scenariosAnd calculating the toughness index of the power grid under the ice disaster by using a state enumeration method.
2. The toughness-based freezing disaster power grid weak link assessment method according to claim 1, wherein the probability P of s of fault scene is calculated based on all lines of the systemsThe method is realized based on the following steps:
in the formula, i is a fault line number in a fault scene s; p is a radical ofiRepresenting the fault probability of the ith line;
correspondingly, the power grid toughness index under ice disaster is calculated by using a state enumeration method according to the probability Ps of the s of the fault scene, and the method is realized by adopting the following mode:
wherein R issysRepresenting a system level toughness index; n represents the number of lines; a represents the set of all lines, Ωk ARepresents a k-th order subset of a; s represents omegak AOne failure of (2); psThe probability of the fault scene s is represented and calculated by a state enumeration method; i issThis indicates the influence of the fault scenario s, i.e., the amount of system load reduction caused by the fault scenario s.
3. The method for evaluating the weak link of the freezing disaster power grid based on the toughness as claimed in claim 1, wherein the step of calculating the element-level toughness index under the ice disaster according to the evaluation toughness index of the power grid comprises the following steps:
calculating the toughness index increment of the power grid caused by the fault of any one line;
and calculating the element-level toughness index under the ice disaster based on the power grid toughness index increment caused by any one line fault.
4. The toughness-based freezing disaster power grid weak link assessment method according to claim 3, wherein the calculation of the power grid toughness index increment caused by any line fault is realized by adopting the following method:
the grid toughness index increment caused by the mth line fault is expressed as:
wherein R issys|pm0 represents the system toughness index when the mth line is not in fault; rsys|pm1 represents the system toughness index when the mth line has certain faults; smRepresenting a set of all fault scenarios containing the mth line fault; delta IsmFor fault scenarios smThe resulting incremental impact;
correspondingly, the element-level toughness index under ice disaster is calculated based on the power grid toughness index increment caused by any one line fault, and the method is realized by adopting the following mode:
in the formula, pm represents the failure probability of the line m.
5. The toughness-based freezing disaster power grid weak link assessment method according to claim 1, wherein the determining of the line fault probability under the ice disaster according to the weather condition comprises:
line ice wind power load L is calculated based on wind power load and ice force load of lineWI；
According to the ice wind load L of the lineWICalculating the line fault probability p per unit lengthf。。
6. The toughness-based freezing disaster power grid weak link assessment method according to claim 2, wherein the line ice wind power load L is calculated based on the line wind power load and ice force loadWIThe method comprises the following steps:
calculating the ice load L of a line of unit lengthI；
According to the ice force load LICalculating the wind load L of the line of unit lengthW(N/m)；
Calculating ice wind load L of lineWI。
7. The toughness-based freezing disaster power grid weak link assessment method according to claim 3, wherein the load L is based on line ice wind powerWICalculating the line fault per unit length includes: the probability pfThe method is realized based on the following steps:
wherein, aWIAnd bWIRespectively a first and a second threshold value (N/m) for the ice wind load.
8. The utility model provides a freezing calamity electric wire netting weak link evaluation device based on toughness which characterized in that includes:
the line fault probability determination module is used for determining the line fault probability under ice disasters according to the weather conditions;
the power grid evaluation toughness index calculation module is used for calculating power grid evaluation toughness indexes according to the fault probabilities of the multiple lines;
the ice disaster lower element level toughness index calculation module is used for calculating an ice disaster lower element level toughness index according to the power grid evaluation toughness index;
the priority determining module is used for determining a prevention priority according to the element-level toughness index under the ice disaster;
the power grid evaluation toughness index calculation module comprises:
the power grid toughness index calculating unit is used for calculating a power grid toughness index under ice disasters based on all lines of the system by using a state enumeration method;
the power grid toughness index calculation unit comprises:
a probability calculation subunit for calculating the probability P of s of the fault scene based on all the lines of the systems，
A power grid toughness index calculation subunit, configured to calculate a probability P of s according to the fault scenariosAnd calculating the toughness index of the power grid under the ice disaster by using a state enumeration method.
9. The toughness-based freezing disaster power grid weak link assessment device according to claim 8, wherein the probability calculation subunit is implemented based on the following manner:
in the formula, i is a fault line number in a fault scene s; p is a radical ofiRepresenting the fault probability of the ith line;
correspondingly, the power grid toughness index calculation subunit is realized by adopting the following mode:
wherein R issysRepresenting a system level toughness index; n represents the number of lines; a represents the set of all lines, Ωk ARepresents a k-th order subset of a; s represents omegak AOne failure of (2); psThe probability of the fault scene s is represented and calculated by a state enumeration method; i issThis indicates the influence of the fault scenario s, i.e., the amount of system load reduction caused by the fault scenario s.
10. The apparatus for evaluating weak link of freezing disaster electric network based on toughness as claimed in claim 8, wherein the module for calculating toughness index of element level under ice disaster comprises:
the index increment calculating unit is used for calculating the toughness index increment of the power grid caused by the fault of any one line;
and the element-level toughness index calculating unit is used for calculating the element-level toughness index under the ice disaster based on the power grid toughness index increment caused by any one line fault.
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