CN111193246B - Fault removal method considering operation mode and switching characteristics - Google Patents

Abstract

The invention relates to a fault removal method considering an operation mode and switching characteristics, which comprises the following steps: 1) Selecting a fault element, 2) calculating the size of a fault resistor, and restoring the size of the fault resistor through electric acquisition information; 3) Selecting a breaker free of expansion action; 4) Selecting a breaker needing to consider the expansion action; 5) And forming a breaker action time sequence coordination based on the action conditions. The fault cutting method considering the operation mode and the switching characteristic establishes the action time limit of the circuit breaker, ensures that the circuit breaker can act within the breaking current, and reduces the cutting range and the action time of the fault as far as possible.

Description

Fault removal method considering operation mode and switching characteristics

Technical Field

The invention relates to the field of separating fault points in a circuit breaker cutting scheme, in particular to a fault cutting method considering an operation mode and switching characteristics.

Background

The large number of grid-connected accesses of the distributed power supply makes the fault current possibly exceed the requirement of interruption current capacity of the switching equipment of the power distribution network, so that the circuit breaker cannot separate the fault point according to the originally customized cutting scheme. On the other hand, the complexity and the variability of the operation modes of the network wiring also make the fault removal strategy to be changed along with the changes of the wiring and the operation modes. Therefore, when considering the action strategy of the circuit breaker of the new background condition of the operation of the power distribution network, the operation mode of the network and the action characteristic of the switch need to be considered.

The current breaker can act, and when actually measured fault current and interruption current are compared, the breaker is locked to act, and the protection of the upper level failure is relied on to expand and cut off, so that an action strategy is blind, an action range is possibly overlarge, action time is possibly overlong, and the power supply reliability of the power distribution network is reduced. Aiming at the problems, the invention provides an action breaker searching algorithm starting from a fault point, which comprises the steps of firstly selecting breaker combinations adjacent to the fault point according to the fault point, deducing the approximate range of fault resistance, forming a fault network under various working conditions including the fault resistance, judging whether the selected breaker combinations can realize fault removal under the breaking characteristics in the fault network under various working conditions, and if so, customizing the action time limit of the breaker; if not, a circuit breaker expansion operation scheme is formed. Thus, the circuit breaker action strategy adjustment according to the operation mode and the switch action characteristic is realized.

According to the first technical scheme, fault removal is carried out through independent work of the circuit breaker, the problem that whether interrupt current and fault current can be matched under the distributed power supply access condition is less considered in the current distribution network circuit breaker configuration, a locking link is added in the action process of the circuit breaker in the traditional scheme, when the actually measured fault current is larger than the interrupt current, a locking strategy is adopted, and fault removal is achieved through the mode that the circuit breaker fails to protect, namely, the protection is expanded.

The first disadvantage of the prior art is: by means of the failure protection method of the circuit breakers, the circuit breakers lack of coordination, the fault removal capability of the circuit breakers is not fully exerted, when fault currents larger than interruption currents occur, all the circuit breakers adopt an enlarged removal method, so that an action interval is overlarge, and on the other hand, the failure protection needs larger time sequence coordination, so that the fault removal time is overlong.

In the second technical scheme, the action combination of the circuit breaker is obtained in a network mode, the action-capable circuit breaker combination is selected according to the breaking capacity of the circuit breaker, and the action is managed in a unified mode by starting action strategies under the centralized mode of the network.

Drawbacks of the second prior art: when a fault strategy is issued, the problem of fault transfer current caused by network structure change in the fault removal process is not considered, and the problem of action current out-of-limit caused by overlarge transfer current can occur, so that serious operation accidents are caused.

Disclosure of Invention

In order to overcome the problems in the prior art, the invention provides a fault removal method considering the operation mode and the switching characteristics, establishes the action time limit of the circuit breaker, ensures that the circuit breaker can act within the breaking current, and reduces the fault removal range and the action time as far as possible.

The technical scheme adopted for solving the technical problems is as follows: a fault removal method considering operation modes and switching characteristics comprises the following steps:

1) Selecting a fault element, determining the fault element by the protection substation according to the electrical quantity information and the switching value information acquired by the terminal, and determining a breaker initial action combination A without considering breaker breaking characteristics according to the position of the fault element ₀ ；

2) Calculating the size of a fault resistor, and restoring the size of the fault resistor through electric acquisition information;

3) Selecting a circuit breaker without expansion;

31 From an initial action breaker combination a ₀ Starting from, judge A ₀ The related breaker can normally act under the current running condition, and A is judged ₀ Whether the N groups of circuit breakers can normally act and separate; the equivalent fault resistance and the fault point obtained through calculation form N groups of fault networks; in the ith group of fault network, except for the closing of the circuit breaker i, the rest circuit breakers are opened;

32 Judging that under the operation condition, the breaker i can cut off the fault current, and if so, the breaker i can be used as a breaker for cutting off the fault current at the last time; breaker combination capable of isolating fault current as a final, expressed as B ₀ ；

33 When B) ₀ Not equal to A ₀ When the fault current is isolated, all the circuit breakers can be used as the circuit breaker for isolating the fault current at last, and at the moment, the circuit breaker for isolating the fault current at the next time is selected; the need to form N-N ₀ Group failure network, n ₀ Is B ₀ The number of circuit breakers, at this time, the formed fault network is B-divided ₀ And the rest of N-N except for the closing of the breaker j ₀ -group 1 circuit breakers open; judging that under the operation condition, the breaker j can cut off the fault current, and if so, the breaker j can be used as a breaker for cutting off the fault current after the next time; breaker combination capable of isolating fault current after secondary, expressed as B ₁ ；

33 When B) ₁ Not equal to B ₀ Step 33) is then looped to form B ₀ 、B ₁ …B _mb Until B _mb +1 is null.

4) Selecting a breaker considering the expansion action;

41 When B) ₀ 、B ₁ …B _mb The union of not equal to A ₀ When A is ₀ The formed breaker action combination cannot realize fault removal under action conditions; formation of a novel breaker combination A ₁ ，A ₁ Is equivalent to B ₀ 、B ₁ …B _mb At A ₀ Complement the below, will A ₁ Instead of A ₀ Substituting into the step 3), a new action breaker combination C is formed ₀ 、C ₁ …C _mc ；

42 Judgment of C) ₀ 、C ₁ …C _mc Whether the union of A is equal to ₁ If equal, completing the extension action breaker selection, if not, further forming A according to the method in step 33) ₂ And forming a breaker combination D through the step 3) ₀ 、D ₁ …D _md The method comprises the steps of carrying out a first treatment on the surface of the And so on until the set equality is satisfied.

5) Time sequence matching of circuit breakers based on action conditions, and the circuit breaker with the highest action time limit is B ₀ Giving maximum action delay and guaranteeing B ₀ The circuit breaker in (a) is subjected to an isolating operation after the other circuit breakers are operated.

The scheme of the invention is realized by combining a communication network, is arranged on intelligent terminal equipment of a breaker, and collects the state of the breaker and the breaking characteristic of the breaker into a topology analysis and protection substation, wherein a function realization part of the scheme is loaded into the protection substation, and the protection substation needs to be completed: fault point positioning, transitional resistance calculation, fault network generation, action capability judgment, breaker combination determination, time sequence determination and other processes, and finally, the protection substation sends a breaker action instruction to a terminal, and the terminal acts on the breaker to realize final fault isolation.

The beneficial effects of the invention are as follows: a fault removal method considering the operation mode and the switching characteristic can be effectively applied to the distributed power supply access and the circuit breaker action condition judgment and action coordination method under the complex operation mode (such as ring network operation and multi-power supply system). The circuit breaker is ensured to be capable of operating within the interruption current, and the cutting range and the operation time of faults can be reduced as much as possible.

Drawings

The invention will be further described with reference to the drawings and examples.

FIG. 1 is a flow chart of a fault removal method accounting for operating mode and switching characteristics according to the present invention;

FIG. 2 is a flow chart of step 3) of the fault removal method accounting for operating mode and switching characteristics of the present invention;

fig. 3 is a flow chart of step 4) of the fault removal method according to the present invention, which takes into account the operation mode and the switching characteristics.

Detailed Description

The invention will now be described in further detail with reference to the accompanying drawings. The drawings are simplified schematic representations which merely illustrate the basic structure of the invention and therefore show only the structures which are relevant to the invention.

In the method of the invention, as shown in fig. 1, the implementation flow of the method is as follows:

1) And selecting a fault element.

The protection substation determines the fault element according to the electrical quantity information and the switching value information acquired by the terminal. Further, according to the position of the fault element, determining a breaker initial action combination A without considering breaker breaking characteristics ₀ ；

2) And calculating the size of the fault resistance.

And the size of the fault resistor is restored through electrical collection information. It should be noted that, the specific position of the current fault and the magnitude of the fault resistance do not need to be accurately calculated, and when the fault occurs on the line and the specific position of the fault cannot be specifically known, the fault point can be assumed to be located in the middle of the line so as to calculate the equivalent fault transition resistance. The reason is that the existence of the equivalent fault resistance is only used for analyzing the effect of the external current drawing and the auxiliary current under the fault condition, so that an accurate calculation result is not needed, on the other hand, the distribution network line is shorter, and the influence caused by the difference of the fault positions is relatively smaller.

3) Expansion-free circuit breaker selection

From initial action breaker combination a ₀ Starting from, judge A ₀ The circuit breaker involved can normally operate under the current running condition. Suppose A ₀ And N groups of circuit breakers are shared, so that the N groups of circuit breakers are required to be opened, and the fault points can be effectively cut off. It is determined whether the N groups of circuit breakers can be normally operated to be separated, and the operation sequence is as shown in fig. 2.

And forming N groups of fault networks according to the calculated equivalent fault resistance and the fault points. Judging that the ith breaker can be isolated from a fault, analyzing that when other breakers are separated, the fault current is transferred to the breaker at the moment, and the working condition of the breaker is the worst at the moment, so that the formed fault network is that the rest N-1 groups of breakers are disconnected except the breaker i which is closed, under the operation condition, the breaker i can cut off the fault current, and if the breaker i can be used as the breaker which cuts off the fault current at the last time; breaker combination capable of isolating fault current as a final, expressed as B ₀ ；

When B is ₀ Not equal to A ₀ When not all the circuit breakers can be used as the circuit breaker for isolating fault current finally, the circuit breaker for isolating fault current after the next time is selected. At this time, N-N needs to be formed ₀ Group failure network, n ₀ Is B ₀ The number of circuit breakers, at this time, the formed fault network is B-divided ₀ And the rest of N-N except for the closing of the breaker j ₀ -1 group of circuit breakers open. Judging that under the operation condition, the breaker j can cut off the fault current, and if so, the breaker j can be used as a breaker for cutting off the fault current after the next time; breaker combination capable of isolating fault current after secondary, expressed as B ₁ ；

And so on can form B ₀ 、B ₁ …B _mb Up to B _mb+1 Is empty.

4) Circuit breaker selection with consideration of enlarging action

When B is ₀ 、B ₁ …B _mb The union of not equal to A ₀ In this case, it can be considered that A ₀ The resulting circuit breaker action combination is incapable of achieving fault removal under action conditions. That is, there will always be a fault current of the circuit breaker during the entire set of actions that exceeds its own interrupting current capacity. At this time, a new breaker operation combination needs to be formed by expanding.

When selecting the enlarged breaker to cut off the fault current, the breaking capacity of the next level breaker is required to be as large as possible, therefore, the next level breaker with the maximum breaking capacity is taken as a preferential selection scheme, and the breaker p is assumed to replace the breaker q to form a new breaker combination A ₁ 。A ₁ Is equivalent to B ₀ 、B ₁ …B _mb At A ₀ Complement the below, will A ₁ Instead of A ₀ Substituting into the step 3), a new action breaker combination C is formed ₀ 、C ₁ …C _mc The method comprises the steps of carrying out a first treatment on the surface of the As shown in fig. 3.

Judgment C ₀ 、C ₁ …C _mc Whether the union of A is equal to ₁ If the current is equal to the current, the selection of the expansion action breaker is completed, if the current is not enough, the similar further formation A ₂ And forming a breaker combination D through the step 3) ₀ 、D ₁ …D _md The method comprises the steps of carrying out a first treatment on the surface of the And so on until the set equality is satisfied.

5) Circuit breaker timing sequence matching based on action conditions

The last action breaker has the highest action time limit of B ₀ Giving maximum action delay and guaranteeing B ₀ The circuit breaker in (a) is subjected to an isolating operation after the other circuit breakers are operated. And so on.

The implementation of the invention can be effectively suitable for the distributed power supply access and the circuit breaker action condition judgment and action coordination method under the complex operation modes (such as ring network operation and multi-power supply system). The circuit breaker is ensured to be capable of operating within the interruption current, and the cutting range and the operation time of faults can be reduced as much as possible.

With the above-described preferred embodiments according to the present invention as an illustration, the above-described descriptions can be used by persons skilled in the relevant art to make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of claims.

Claims (1)

1. A fault removal method considering operation modes and switching characteristics is characterized in that: the method comprises the following steps:

1) Selecting a fault element, determining the fault element by the protection substation according to the electrical quantity information and the switching value information acquired by the terminal, and determining a breaker initial action combination A without considering breaker breaking characteristics according to the position of the fault element ₀ ；

2) Calculating the size of a fault resistor, and restoring the size of the fault resistor through electric acquisition information;

3) Selecting a circuit breaker without expansion;

31 Judgment of A) ₀ The related breaker can normally act under the current running condition, and A is judged ₀ Whether the N groups of circuit breakers can normally act and separate; the equivalent fault resistance and the fault point obtained through calculation form N groups of fault networks; for the i-th group fault network, the rest of the circuit breakers are opened except for the circuit breaker i which is closed;

32 Judging the breaker i as the breaker for finally isolating the fault current according to the fault current of the isolating breaker i, and expressing the breaker combination for finally isolating the fault current as B ₀ ；

33 When B) ₀ Not equal to A ₀ When the fault current is isolated, all the circuit breakers can be used as the circuit breaker for isolating the fault current at last, and at the moment, the circuit breaker for isolating the fault current at the next time is selected; the need to form N-N ₀ Group failure network, n ₀ Is B ₀ The number of circuit breakers, at this time, the formed fault network is B-divided ₀ And the rest of N-N except for the closing of the breaker j ₀ -group 1 circuit breakers open; judging that under the operation condition, the breaker j can cut off the fault current, and if so, the breaker j can be used as a breaker for cutting off the fault current after the next time; breaker combination capable of isolating fault current after secondary, expressed as B ₁ ；

34 When B) ₁ Not equal to B ₀ Step 33) is then looped to form B ₀ 、B ₁ …B _mb Until B _mb+1 Is empty;

4) Selecting a breaker considering the expansion action;

41 When B) ₀ 、B ₁ …B _mb The union of not equal to A ₀ When A is ₀ The formed breaker action combination cannot realize fault removal under action conditions; formation of a novel breaker combination A ₁ ，A ₁ Is equivalent to B ₀ 、B ₁ …B _mb At A ₀ Complement the below, will A ₁ Instead of A ₀ Substituting into the step 3), a new action breaker combination C is formed ₀ 、C ₁ …C _mc ；

42 Judgment of C) ₀ 、C ₁ …C _mc Whether the union of A is equal to ₁ If equal, completing the extension action breaker selection, if not, further forming A according to the method in step 33) ₂ And forming a breaker combination D through the step 3) ₀ 、D ₁ …D _md The method comprises the steps of carrying out a first treatment on the surface of the And so on until set equality is satisfied;

5) Time sequence matching of circuit breakers based on action conditions, and the circuit breaker with the highest action time limit is B ₀ Giving maximum action delay and guaranteeing B ₀ The circuit breaker in (a) is subjected to an isolating operation after the other circuit breakers are operated.

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