CN105896534B - Meter and the transmission system malfunction collection screening technique of circuit importance and the degree of association - Google Patents

Abstract

The invention relates to a fault state screening method in the field of electric power technology, in particular to a fault state set screening method for a power transmission system taking into account line importance and correlation, including step 1, determining line importance and correlation; step 2, determining line The probability factor of ; Step 3, determine the importance factor of the line; Step 4, determine the first-order fault set of the system; Step 5, determine the n -order fault set of the system. The invention takes into account the influence of the dual factors of criticality and reliability of the line, and screens fault sets that seriously affect the reliability of the system. The invention has fast convergence speed and short calculation time, can reflect the reliability level of the system more realistically, and is a very promising fast screening method for fault state sets of power system reliability evaluation.

Description

Transmission system fault state set screening method considering line importance and correlation

technical field

The invention relates to a method for screening a fault state set in the field of electric power technology, in particular to a method for screening a fault state set for a power transmission system taking into account the importance and correlation of lines.

Background technique

As the scale of the power grid continues to expand, the number of components increases rapidly in a geometric progression, and the possibility of random failures in the power system increases accordingly. With the development of electrification, electricity has been related to all aspects of the national economy. If random events cause the loss of power system functions, it will bring huge economic and social losses. It is the key to ensure the reliable operation of the system to truly evaluate the reliability level of the power system and use it as a basis to guide the planning and dispatching of the power grid.

The power system can generally be divided into power generation system, power transmission system and power distribution system. Due to the large scale of the power grid, reliability evaluation is usually divided into power generation system reliability evaluation, power transmission system reliability evaluation, power distribution system reliability evaluation, etc. Reliability assessment generally includes system failure state set selection, failure consequence analysis and reliability index calculation. Among them, when selecting the fault state set, generally to simplify the calculation, the components are usually equivalent to a two-state model, that is, the components are considered to have only two states of working and shutdown. Assuming that the system includes n components, there may be 2 ⁿ types of systems Operating state, limited by computing resources and computing time, it is impossible to evaluate all fault states. Therefore, it is necessary to design a reasonable algorithm to evaluate the fault states that have a great impact on system reliability, such as using technologies such as fault multiplicity limitation, truncation probability, and fault classification to reduce the amount of calculation. However, the general failure state selection only considers the impact of the probability of failure on reliability, and high-probability events in the actual power system may not necessarily cause a large impact, but some low-probability events may cause large-scale blackouts and even cause system failures. collapse. Only considering the probability of failure to analyze the reliability of power system may cause the evaluation result to be too optimistic. For example, the high-voltage transmission line of the power system, because it plays a very important role in the system, usually the power company will take various measures to improve its reliability, and its outage rate is generally low. If you simply consider the failure probability, you may ignore this type The system failure state caused by the transmission line cannot take into account the impact of this part of the failure consequences on the system reliability. Similarly, if only the severity of the consequences of the event is considered, the evaluation result may be too pessimistic, especially with the development of ultra-high voltage and ultra-high voltage transmission technology, once the long-distance high-power transmission line fails, it will cause a huge power imbalance, and even cause The system is unstable. At this time, if we only consider the consequences of the failure and do not take into account the probability of the occurrence of the event to arrange the scheduling strategy, the economical efficiency of the system operation will be greatly reduced.

For the power transmission system, due to more influencing factors and complex nonlinear relationships between lines, it is more difficult to make a reasonable assessment of the reliability of the system taking into account the influence of lines, such as line capacity, actual power flow, topological location , trend weight, etc. Moreover, once the system fails, due to changes in the grid structure, the importance of all lines in the new grid will be different from that of the original grid, which will also have an impact on the determination of multiple faults in the reliability assessment, and the lines in the original grid will still be used It will lose the effect of sorting the importance of the line to determine the importance of the line, and recalculating the importance of the line every time the power grid changes will make the calculation time too long, increase the cost of reliability evaluation, and even make the scheme Not feasible due to computational resource constraints. In order to balance the economy and reliability of the power system, it is necessary to design a reasonable fault state set screening method to reflect the reliability level of the power system as truly as possible. Therefore, when evaluating the reliability of the transmission system, the probability of occurrence of events and the position of the line in the power system must be taken into consideration, and the fault state set of the transmission system must be determined comprehensively.

Contents of the invention

In order to solve the problem of large evaluation errors caused by single consideration factors in the existing power system reliability evaluation method, the present invention provides a transmission system fault state set screening method considering line importance and correlation. This method uses line importance to determine first-order faults, and determines multi-order faults according to correlation degree, so as to improve the efficiency and accuracy of reliability evaluation.

The present invention is realized by adopting the following technical scheme: a method for screening the fault state set of the power transmission system taking into account the line importance and correlation degree, comprising the following steps:

Step 1: Determine the line importance and relevance:

(1) Determine the absolute power flow factor of line i That is, the ratio of the absolute power flow of line i to the upper limit of transmission capacity of line i, where l is the number of system lines, q is the number of system units, is the absolute power flow on line i, P _imax is the upper limit of the transmission capacity of line i, P _ks is the active power generated by generator k, is the generator branch power distribution factor, that is, the ratio of the active power emitted by generator k and injected into line i to the active power emitted by generator k;

(2) Determine the weight factor of line i G is the set of lines directly connected to the generator, and P _i is the actual active power flow in line i. That is, for ordinary lines, its weight factor is the line load rate; for generator direct connection lines, its weight factor is the sum of the line load rate and the ratio of line transmission power to the total system power generation;

(3) Determine the criticality factor of line i The greater the criticality factor of the line, the greater the absolute power flow factor of the line or the greater the weight factor of the line, that is, the higher the importance of the line in the system;

(4) Determine the correlation factor between lines And j≠i. The greater the correlation factor between any two lines i and j, the closer their roles in transmission power are. Once they fail at the same time, the power carried on them is likely to be unable to be transmitted due to transmission capacity constraints, resulting in system Load shedding reduces reliability;

Step 2: Determine the probability factor θ _i =p _di /p _ui of line i, where p _di is the outage probability of line i, and p _ui is the operation probability of line i;

Step 3: Determine the importance factor φ _i = θ _i F _i of the line i, that is, the line criticality factor weighted by the line probability factor, considering the line criticality factor and the line probability factor comprehensively, the greater the probability and the more important the line fault The greater the impact on the reliability of the system in the end;

Step 4: Determine the first-order fault set of the system: the fault of a single component of the system is called the first-order fault. According to the sequence of the line importance factor φ _i = θ _i F _i from large to small, the line i fault is set in sequence, as a system fault state;

Step 5: Determine the n-order fault set of the system: the state with n component faults in the system is called n-order fault, 1<n<l. On the basis of the first-order fault set, the correlation factors of the remaining lines and the faulty lines are determined, and the remaining lines are sorted according to the correlation factors to obtain the second-order fault set. On the basis of the second-order fault set, determine the correlation factors of the remaining lines and the two fault lines, and select the largest correlation factor multiplied by the correlation factor of the second-order state line as the line of the third-order fault state The correlation degree factor of , the fault states are sorted according to the correlation degree factor, and the third-order fault set is obtained. By analogy, on the basis of the k (k>2) order fault set, determine the correlation factor of the remaining lines and the k fault lines, and select the largest correlation factor among them and multiply it with the correlation factor of the kth order state line As the correlation degree factor of the line in the state of the k+1-order fault, the fault states are sorted according to the correlation degree factor to obtain the k+1-order fault set. Using quick sorting technology, the n-order fault state of the system is determined in turn, thereby determining the n-order fault set of the system, and finally the first-order to n-order fault sets are obtained.

This method takes into account the influence of line criticality and line probability factors, and proposes line importance factors. By sorting the line importance factors, the first-order fault set of the power system is determined, and on the basis of the first-order fault set, according to The line correlation factor determines the n-order fault state set of the system. The fault set rapid screening method selects the state that has a greater impact on system reliability for evaluation, which can evaluate the reliability level of the system more reasonably and provide feasible suggestions for power system planning and dispatching operation.

Detailed ways

A transmission system fault state set screening method that takes into account line importance and correlation includes the following steps:

Step 1: Determine the line importance and relevance:

(1) Determine the absolute power flow factor of line i Where l is the number of lines in the system, q is the number of units in the system, is the absolute power flow on line i, P _imax is the upper limit of the transmission capacity of line i, P _ks is the active power generated by generator k, is the power distribution factor of the generator branch.

(2) Determine the weight factor of line i G is the set of lines directly connected to the generator, and P _i is the actual active power flow in line i.

(3) Determine the criticality factor of line i

(4) Determine the correlation factor between lines And j≠i.

Step 2: Determine the probability factor θ _i =p _di /p _ui of line i, where p _di is the outage probability of line i, and p _ui is the operation probability of line i.

Step 3: Determine the importance factor φ _i =θ _i F _{i of the line i} .

Step 4: According to the order of line importance factors φ _i = θ _i F _i from large to small, sequentially set line i faults, and determine the first-order fault state set of the system.

Step 5: Determine the n-order fault set of the system: the state with n component faults in the system is called n-order fault, 1<n<l. On the basis of the first-order fault set, the correlation factors of the remaining lines and the faulty lines are determined, and the remaining lines are sorted according to the correlation factors to obtain the second-order fault set. On the basis of the second-order fault set, determine the correlation factors of the remaining lines and the two fault lines, and select the largest correlation factor multiplied by the correlation factor of the second-order state line as the line of the third-order fault state The correlation degree factor of , the fault states are sorted according to the correlation degree factor, and the third-order fault set is obtained. For example, the second-order fault includes the fault line (1, 2), then when determining the third-order fault, select the larger correlation factor between line 3 and line 1 and line 2, then the third-order fault (1, 2, 3) The correlation factor is On the basis of the k (k>2) order fault set, determine the correlation factor of the remaining lines and the k fault lines, and select the largest correlation factor multiplied by the correlation factor of the kth order state line as the k The correlation factor of the line in the state of the +1-order fault, sort the fault states according to the correlation factor, and obtain the k+1-order fault set. Using quick sorting technology, the n-order fault state of the system is determined in turn, thereby determining the n-order fault set of the system, and finally the first-order to n-order fault sets are obtained.

The transmission system fault state set screening method of the present invention, which takes into account the line importance and correlation, comprehensively considers the role of the line in the system and the probability of reliable operation of the line, and can take into account both high-probability non-serious events and low-probability serious consequence events. A more comprehensive evaluation of the reliability level of the power system, with fast convergence speed and relatively short calculation time, is a promising method for rapid screening of fault state sets for power system reliability evaluation.

Claims (1)

1. meter and the transmission system malfunction collection screening technique of circuit importance and the degree of association, it is characterised in that including following step Suddenly：

Step 1：Determine circuit importance and the degree of association：

(1) the absolute trend factor of circuit i is determinedWherein l is system line Number, q is system unit number,For the absolute trend on circuit i, P_imaxFor the transmission capacity upper limit of circuit i, P_ksFor generator k The active power sent,For generator branch power distribution factor；

(2) weight factor of circuit i is determinedG be and the direct-connected line set of generator, P_iFor line Actual effective power flow in the i of road；

(3) the criticality factor of circuit i is determined

(4) degree of association factor between circuit is determinedJ=1,2 ... ..., l, and j ≠ i；

Step 2：Determine the probability factor θ of circuit i_i=p_di/p_ui：Wherein p_diFor the stoppage in transit probability of circuit i, p_uiFor circuit i's Run probability；

Step 3：Determine the importance factors φ of circuit i_i=θ_iF_i；

Step 4：According to circuit importance factors φ_i=θ_iF_iOrder from big to small, sets circuit i failures successively, determines system The single order malfunction collection of system；

Step 5：On the basis of single order malfunction collection, the degree of association factor of remaining circuit and faulty line is determined, by remaining Circuit sorts by the degree of association factor, using fast sorting technique is improved, determines the n rank malfunctions of system successively, determines system N rank malfunction collection, 1<n<L, finally obtains single order to n rank malfunction collection.