CN104133968A - Correlation assessment method of power grid cascading failure accident chains - Google Patents

Abstract

A correlation assessment method of power grid cascading failure accident chains comprises the steps that (1) a system is initialized to be in a normal operation working condition; (2) initial failures happen to circuits with equal probability, circuit initial failures are circuit three-phase permanent short-circuit failures, relay protecting action failure removing in a set time is carried out, and for direct-current circuit, the initial failures are direct-current circuit single-pole locking failures; (3) based on the previous circuit failure situations, transient stability analysis is carried out on an electric system, if system transient is unstable, the step (7) is carried out; and if system transient is stable, the step (4) is carried out; and other steps are carried out. According to the method, on the basis that the correlation between cascading failures can be considered, system transient stability failures can be subjected to effective searching, searching correlation probability is given, system states and topology are considered, meanwhile, high computing efficiency is achieved, and certain guiding effect is achieved on cascading failure searching and accident chain recognition.

Description

The relevance evaluation method of power grid cascading failure accident chain

Technical field

The present invention relates to be applied in the Study of Risk Evaluation Analysis for Power System method in Operation of Electric Systems, safety monitoring system, belong to the figure computer technology of touching upon and be applied to the technical field of Operation of Electric Systems planning.

Background technology

In recent years, along with electrical network scale constantly expands, electrical equipment constantly increases, the accident of having a power failure on a large scale causes electrical network affects increasingly significant, and the complicacy breaking down increases day by day, and Chinese scholars is being carried out extensive and deep research from the angle of have a power failure on a large scale accident mechanism and model.

In world wide, the accident of having a power failure on a large scale happens occasionally, for example 2003 " U.S.A add have a power failure on a large scale ", Denmark and Sweden has a power failure on a large scale, Italy has a power failure on a large scale, for another example South Africa in 2006 and West Europe has a power failure on a large scale, India in 2012 has a power failure on a large scale etc.Take world-shaking " U.S.A add have a power failure on a large scale " be example, there is power outage on August 14th, 2003 in Northeastern United States, affected Canadian part power supply simultaneously, and power-off condition has continued at least four days, directly caused the economic loss of approximately 6,000,000,000 dollars, involved and surpassed 40,000,000 populations.The accident of having a power failure on a large scale has exposed error and the defect in U.S.'s electric network composition and configuration specifically, comprise that electromagnetic looped network, electric pressure differ, load factor is crossed the problems such as high under electrical network nominal situation, certainly, the emergency preplan of shortage reply emergency condition is also one of further factor expanding of accident.Although the initiation reason of the accident of respectively having a power failure on a large scale is different, development is also not quite similar, but the continuous expansion of accident is caused by cascading failure substantially, objectively proved the importance of research cascading failure development mechanism and the analog computation of being correlated with, simultaneously, just initiation and the development due to the accident of having a power failure on a large scale itself do not have set rule and pattern, and lacks relevant actual test case in world wide, brought certain difficulty to cascading failure modeling and simulating.The mechanism research of cascading failure is mainly divided into conventionally: take power system mesomeric state trend and transient stability analysis as modeling basis, consider the probability of happening of the system actions such as the load rate of transform, relay protection device tripping malfunction probability, line failure rate, cascading failure development model and development trend thereof and system state are analyzed, based on system state in model, provided diagnosis and corresponding control strategy; Take electric system topology as analysis foundation, topological relation with abstract is described Power grid structure, by Complex Networks Theory, system state and behavior are carried out to analysis and assessment, on a macro scale cascading failure pattern and system topological are carried out to qualitative analysis, with this, from topological angle, understand its mechanism.

On the whole, the analysis and research of cascading failure mainly launch from system state and topological structure two aspects, but wherein the relevance between cascading failure is seldom furtherd investigate, from aforementioned cascading failure pattern analysis, although the realistic model that the first kind changes for electric system state quantity can effectively be simulated cascading failure process, if but lacking the considering of cascading failure correlativity, its analog result can not accurately reflect the actual conditions of electrical network, will ignore important cascading failure pattern.

Summary of the invention

The object of the invention is some problems that exist in existing cascading failure pattern search and Analysis on Mechanism, proposed the relevance evaluation method of power grid cascading failure accident chain.Main research of the present invention is: first, set up electrical network basic framework, based on Power System Steady-state AC power flow and transient stability analysis, system state (comprising Line Flow, generator's power and angle) is carried out to computational analysis; Then, on the basis of electrical network framework, the relay protection malfunction of the failure dependency based between cascading failure and circuit, adopts the mode of roulette to develop at random cascading failure by different probability; Finally, the structure of the master routine based on C++ and calling external program are realized analogue system.

The relevance evaluation method of power grid cascading failure accident chain, comprises the following steps:

(1) by system initialization, be accidental conditions;

(2) each circuit equiprobability generation primary fault, circuit primary fault is circuit three-phase permanent short fault, relay protection action excision fault in given time.For DC line, primary fault is DC line one pole locking fault;

(3) the line fault situation based on before, carries out transient stability analysis to electric system; If system transient modelling unstability, enters (7); If power system transient stability, enters (4);

Define system transient stability index is weighed power system transient stability degree:

$\mathrm{\η}=\frac{360-{\mathrm{\δ}}_{\max }}{360+{\mathrm{\δ}}_{\max }}\×100$

Wherein, δ _maxfor system maximum work angular difference in transient state process, index be on the occasion of time, system stability, when index is negative value, system unstability, index and system maximum work angular difference correlation;

(4) according to topology distance between Line Flow variation and faulty line, judge whether to occur next stage fault;

Between failure definition circuit, topology distance is as the important indicator of weighing failure dependency, its implication be two circuits separately between two summits circuit that shortest path comprises count the mean value of sum, for circuit i and circuit j, two summits of circuit i and two summits of circuit j can obtain four shortest paths, calculate the average that each shortest path comprises number of lines sum, be:

$D=\frac{1}{4}\mathrm{\Σd}$

Wherein, D represents topology distance between circuit, and d represents number of path between summit;

Set every one-level a line fault only occurs, if exist Line Flow to surpass the certain proportion of trend under accidental conditions and less with current faulty line topology distance, be called trend out-of-limit, or trend transfer amount surpasses the certain proportion of trend before current faulty line fault and less with current faulty line topology distance, being called trend shifts, there is next stage fault, enter (5), otherwise enter (7); Topology distance between circuit, be two circuits separately between two summits shortest path count the mean value of sum;

(5) according to topology distance between Line Flow and faulty line, calculate the fault degree of correlation;

The failure definition degree of correlation is proportional to the front trend of its fault, is inversely proportional to topology distance between cascading failure,

$A=\frac{P}{P_{\mathrm{norm}}D}$

Wherein, A is the degree of correlation between faulty line, and P is meritorious trend before next stage faulty line fault, P _normfor meritorious trend under next stage faulty line accidental conditions, D is topology distance between faulty line;

(6) using the circuit degree of correlation as weight, adopt the mode of roulette to select at random next stage fault;

(7) this cascading failure circulation finishes, and records this cascading failure pattern;

After completing the cascading failure pattern search circulation of certain number of times, using each accident chain frequency to account for total simulation times and search for association probability as it.

The present invention is based on existing cascading failure searching method, the relevance evaluation method of the power grid cascading failure accident chain of proposition.The inventive method can considered on the basis of correlativity between cascading failure, effectively power system transient stability fault is searched for, and provide search association probability, taking into account system state and topological in, there is higher counting yield, the identification of the search of cascading failure and accident chain is had to certain directive function.

Accompanying drawing explanation

Fig. 1 is overall composition of the present invention;

Fig. 2 is process flow diagram of the present invention;

Fig. 3 is the topological schematic diagram between circuit of the present invention;

Fig. 4 is the system line figure of employing IEEE39 node system of the present invention;

Fig. 5 is that accident chain is arranged from small to large according to temporarily steady index, gets the accident chain tables of data of first 20.

Embodiment

Main research of the present invention is as shown in Figure 1: first, set up electrical network basic framework, based on Power System Steady-state AC power flow and transient stability analysis, system state (comprising Line Flow, generator's power and angle) is carried out to computational analysis; Then, on the basis of electrical network framework, the relay protection malfunction of the failure dependency based between cascading failure and circuit, adopts the mode of roulette to develop at random cascading failure by different probability; Finally, the structure of the master routine based on C++ and calling external program are realized analogue system.

Idiographic flow is as shown in Figure 2: first, by system initialization, be accidental conditions, and each circuit equiprobability generation primary fault.If system transient modelling unstability, this search finishes.Otherwise enter, judge whether to occur next stage fault, if do not occurred, this search finishes, otherwise according to the fault degree of correlation as weight, adopt the mode of roulette to select at random next stage fault, so circulation.After completing the cascading failure pattern search circulation of certain number of times, using each accident chain frequency to account for total simulation times and search for association probability as it.

With reference to Fig. 1, Fig. 2, the relevance evaluation method of power grid cascading failure accident chain is implemented as follows:

(1) by system initialization, be accidental conditions.

(2) each circuit equiprobability generation primary fault, circuit primary fault is circuit three-phase permanent short fault, relay protection action excision fault in given time.For DC line, primary fault is DC line one pole locking fault.

(3) the line fault situation based on before, carries out transient stability analysis to electric system.If system transient modelling unstability, enters (7).If power system transient stability, enters (4).

Define system transient stability index is weighed power system transient stability degree:

$\mathrm{\η}=\frac{360-{\mathrm{\δ}}_{\max }}{360+{\mathrm{\δ}}_{\max }}\×100$

Wherein, δ _maxfor system maximum work angular difference in transient state process, index be on the occasion of time, system stability, when index is negative value, system unstability, index and system maximum work angular difference correlation.

(4) according to topology distance between Line Flow variation and faulty line, judge whether to occur next stage fault;

Between failure definition circuit, topology distance is as the important indicator of weighing failure dependency, its implication be two circuits separately between two summits circuit that shortest path comprises count the mean value of sum, for circuit i and circuit j, two summits of circuit i and two summits of circuit j can obtain four shortest paths, calculate the average that each shortest path comprises number of lines sum, be:

$D=\frac{1}{4}\mathrm{\Σd}$

Wherein, D represents topology distance between circuit, and d represents number of path between summit, by Di Jiesitela algorithm, calculates.Topology distance is shorter, and failure dependency is better.

For example, as shown in Figure 3, topology distance between the circuit of two overstrikings of calculating:

There is d _aC=2, d _bC=1, d _aD=3, d _bD=2, D=(2+1+3+2)/4=2 so.It should be noted that the correctness that adopts assurance that Di Jiesitela algorithm can more efficient to calculate shortest path between B point and D point.

Only there is a line fault in the every one-level of model specification, if exist Line Flow to surpass trend and less with current faulty line topology distance under accidental conditions, be called trend out-of-limit, or trend transfer amount surpasses the certain proportion (30%) of trend before current faulty line fault and less with current faulty line topology distance, being called trend shifts, there is next stage fault, enter (5), otherwise enter (7); Topology distance between circuit, be two circuits separately between two summits shortest path count the mean value of sum;

(5) according to topology distance between Line Flow and faulty line, calculate the fault degree of correlation.

The failure definition degree of correlation is proportional to the front trend of its fault, is inversely proportional to topology distance between cascading failure,

$A=\frac{P}{P_{\mathrm{norm}}D}$

Wherein, A is the degree of correlation between faulty line, and P is meritorious trend before next stage faulty line fault, P _normfor meritorious trend under next stage faulty line accidental conditions, D is topology distance between faulty line.

(6) using the circuit degree of correlation as weight, adopt the mode of roulette to select at random next stage fault.

(7) this cascading failure circulation finishes, and records this cascading failure pattern.

After completing the cascading failure pattern search circulation of certain number of times, using each accident chain frequency to account for total simulation times and search for association probability as it.

Adopt IEEE39 node system as concrete enforcement example, system line figure as shown in Figure 4, by the simulation analysis of IEEE39 node system being searched to the accident chain that probability of happening is higher.

Claims (1)

1. the relevance evaluation method of power grid cascading failure accident chain, is characterized in that, comprises the following steps:

(1) by system initialization, be accidental conditions;

(2) each circuit equiprobability generation primary fault, circuit primary fault is circuit three-phase permanent short fault, relay protection action excision fault in given time; For DC line, primary fault is DC line one pole locking fault;

(3) the line fault situation based on before, carries out transient stability analysis to electric system; If system transient modelling unstability, enters (7); If power system transient stability, enters (4);

Define system transient stability index is weighed power system transient stability degree:

$\mathrm{\η}=\frac{360-{\mathrm{\δ}}_{\max }}{360+{\mathrm{\δ}}_{\max }}\×100$

Wherein, δ _maxfor system maximum work angular difference in transient state process, index be on the occasion of time, system stability, when index is negative value, system unstability, index and system maximum work angular difference correlation;

(4) according to topology distance between Line Flow variation and faulty line, judge whether to occur next stage fault;

Between failure definition circuit, topology distance is as the important indicator of weighing failure dependency, its implication be two circuits separately between two summits circuit that shortest path comprises count the mean value of sum, for circuit i and circuit j, two summits of circuit i and two summits of circuit j can obtain four shortest paths, calculate the average that each shortest path comprises number of lines sum, be:

$D=\frac{1}{4}\mathrm{\Σd}$

Wherein, D represents topology distance between circuit, and d represents number of path between summit;

Set every one-level a line fault only occurs, if exist Line Flow to surpass the certain proportion of trend under accidental conditions and less with current faulty line topology distance, be called trend out-of-limit, or trend transfer amount surpasses the certain proportion of trend before current faulty line fault and less with current faulty line topology distance, being called trend shifts, there is next stage fault, enter (5), otherwise enter (7); Topology distance between circuit, be two circuits separately between two summits circuit that shortest path comprises count the mean value of sum;

(5) according to topology distance between Line Flow and faulty line, calculate the fault degree of correlation;

The failure definition degree of correlation is proportional to the front trend of its fault, is inversely proportional to topology distance between cascading failure,

$A=\frac{P}{P_{\mathrm{norm}}D}$

Wherein, A is the degree of correlation between faulty line, and P is meritorious trend before next stage faulty line fault, P _normfor meritorious trend under next stage faulty line accidental conditions, D is topology distance between faulty line;

(6) using the circuit degree of correlation as weight, adopt the mode of roulette to select at random next stage fault;

(7) this cascading failure circulation finishes, and records this cascading failure pattern;

After completing the cascading failure pattern search circulation of certain number of times, using each accident chain frequency to account for total simulation times and search for association probability as it.