JP2966001B2 - Distribution line accident diagnosis method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a distribution line accident diagnosis method capable of efficiently searching for an accident section using multi-point sensor information and performing quick load interchange processing.

[Conventional technology]

Conventionally, protection and accident diagnosis in the event of a failure in the distribution system
Basically, this has been done with distribution line protection relays installed at each distribution substation.

In addition, the search for the accident section has been carried out by opening the circuit breakers of the substation, opening the circuit breakers of the substation in sequence by time-sequential transportation, and then opening the circuit breakers of the substation again.

On the other hand, if sensors are installed not only in substations but also in various parts of the distribution system, the information is collected, and the results are collected in one place through an information transmission network using optical fiber cables, it will be possible to search for the accident section And rapid load interchange processing (Togami, et al., “Load interchange processing method by two-step operation in case of power outage in distribution system,” IEEJ Power Technology Research Group, PE-89-151
(See Hiramoto-7)). Therefore, by opening the switch or circuit breaker during the accident section before the circuit breaker of the substation shuts down, accident processing can be performed without power interruption except in the accident section. This means that high quality electricity can be supplied to consumers today in the information society. Also, by collecting micro-grounding information and analyzing its waveform, it is possible to estimate the cause of the accident or predict the accident (Kubo, et al. “Correlation between distribution line accident cause and zero-phase component”, Showa) 59 IEEJ National Convention, No.993, Togami,
In addition, the “accident diagnosis expert system based on distribution line multipoint information” (see Hiramoto (first term) IPSJ National Convention, No. 3D-7) is also possible.

In this case, knowledge engineering approach is effective. The first reason is from the viewpoint of achieving a higher degree of automation. Automation is aimed at efficient and rational automation of large-scale systems by introducing system technology.
However, in the planning, design, realization, and operation of systems, it is becoming increasingly difficult to secure a large number of experienced engineers and technicians. There is a problem of realizing a flexible system that can respond to such needs, and it is to meet such needs.

Second, from the perspective of overcoming the software crisis. There are issues such as improving the productivity of large-scale software and reducing software maintenance costs. It is expected to contribute to improving the actual situation of labor-intensive software production and adjusting the gap between the level of the user's required specifications and the level of the programming language that realizes it.

Third, from the viewpoint of a new approach to the bad structure problem. FA (Factory Automation), OA (Office Au
The demands on tomation) or LA (laboratory automation) are becoming more complex and large-scale, but most of the related issues are badly structured and difficult to handle with conventional systems science methodologies. is there. Here is a need to solve this problem.

[Problems to be solved by the invention]

However, knowledge such as accident section determination and estimation of the cause of the accident has not been completely obtained at present, and the performance of the system must be improved while accumulating and correcting the knowledge in the future.

Accordingly, it is required to use an extract system having high modularity, high knowledge correction and high knowledge readability for the accident diagnosis.

The accident detection and accident type judgment system and the accident section judgment system need to perform the accident section judgment and the accident section separation before the substation circuit breaker opens. Therefore, efficient accident detection and accident type determination are desired.

Various disconnection accidents have been proposed in the past, but cannot be completely detected, and a more reliable method is desired.

The problem to be solved by the present invention is to solve such a conventional problem.

[Means for solving the problem]

In order to solve this problem, the present invention provides an accident detection and accident type determination, an accident section search, and an accident cause diagnosis using a multipoint sensor information distribution line accident diagnosis and extraction system and a conventional procedural expression (procedural algorithm). , Hierarchized into four small systems of accident frequency data collection, facilitating the construction, verification, and correction of knowledge, increasing the reliability of accident section search by comprehensively judging various data, and each element of accident waveform Is expressed fuzzy, an accident cause diagnosis is performed based on the expression, and accident frequency data is collected to enable accident prediction.

[Action]

By doing so, the information of substations and various parts of distribution lines are measured by sensors, and the results are collected and processed at one place through an information transmission network using optical fiber cables,
Comprehensive protection and accident diagnosis can be performed for the entire distribution system.

〔Example〕

 Hereinafter, the present invention will be specifically described based on examples.

The graph representation of the distribution system and sensor arrangement are described.
In general, the power distribution system has a loop distribution, and the normally open switch on the system is open. Therefore, the circuit breaker and the switch can be represented in a tree-like form with a branch and a branch point as a node.

 FIG. 5 shows an example of a distribution system represented by a graph.

In general, the distribution system uses a bank breaker B from a transformer T (T ₁ , T ₂ ) that reduces a transmission voltage to a distribution voltage at a substation P.
Powered on (B ₁ ~B ₄₎ through the bank bus Q (Q ₁ ~Q _4). A tie-bank breaker TB (TB _{1 to} TB ₃ ) is provided between the bank buses Q ₁ and Q _2, between Q ₂ and Q _{3, and} between Q ₃ and Q _4. Power can be exchanged from the transformer T.

At this time, power, from each bank bus via a feeder breaker F (F ₁ ~F ₁₂₎ is supplied to each feeder. Section switch K to separate the section (K ₁ ~K ₂₆₎ is provided in each feeder.

In general, each feeder is provided with a normally open switch connected to other supply points or other routes and usually open at key points of the feeder. By closing the normally open switch, power is supplied from another supply point or another route, and the load in the power failure section is accommodated to eliminate or reduce the power failure section. The distribution system is tree-shaped because the interconnected normally open switch is always open. For simplicity, the illustration of this interconnected normally open switch is omitted in the figure. In addition, some feeders are specifically described, and other feeders are the same, so description is omitted.

Sensors TS, BS, FS, and KS for detecting and sending distribution line information are provided at the outlets of the distribution equipment such as the transformer T, the bank breaker B, the feeder breaker F, and the sectional switch K, respectively. When the distribution line is long, a sensor PS is provided at a necessary position at a position where the section divided by the division switch K is further divided, for example, on a support of a distribution line.

Is the open state of the segment switch, Indicates the closed state of the segment switch, and indicates the branch point of the distribution line.

FIG. 5 is a graphical representation of the arrangement of sensors arranged in the distribution system of FIG.

A sensor TS installed on the power supply side of the substation installed inside the substation mainly for accident detection and accident type judgment
And a sensor BS to be installed in the bank breaker and a sensor FS to be installed in the feeder breaker are arranged hierarchically, and further, a sensor KS to be installed at each switch of the distribution line mainly for searching for an accident section, Power is distributed to the sensor PS installed in such as. Since then, the sensor installed on the power supply side of the substation is TS, the sensor installed on the bank breaker is BS, the sensor installed on the feeder breaker is FS, the sensor installed on each switch is KS, the sensor installed on the utility pole etc. Is PS.

FIG. 1 shows the input information of the system and the system configuration. As shown in the figure, this system is hierarchized by function into four small systems 11 to 14: accident detection and accident type judgment, accident section search, accident cause diagnosis, and accident frequency data collection. And facilitates verification and correction.

The small system 11 for detecting an accident and determining the type of an accident mainly detects a zero-phase voltage, a zero-phase current, a line current, and the like by a sensor installed in a substation, and performs the detection of the accident and the determination of the type of the accident.

The accident detection is performed using signals from substation sensors or feeder sensors, and depending on the type of accident, detection is performed by combining signals from sensors in various parts of the distribution line. A bank sensor that captures less sensor signals has a higher scanning frequency and faster detection. However, the threshold value must be set higher, and the detection accuracy may be reduced, resulting in missed detection. In a feeder sensor having a large number of sensor signals to be captured, the scanning frequency is low and detection is slow. However, the detection accuracy can be increased by lowering the threshold value.

Accident section search system activated by this system
In step 12, an accident section is searched based on the polling information such as the zero-phase voltage and the zero-phase current phase angle at various points in the distribution line. In the accident cause diagnosis system 13 started after the judgment of the accident section, the zero-sequence voltage,
The cause of the accident is inferred using the integrated distortion factor, DC component and harmonic component of each zero-phase current as elements. The accident frequency data collection system 14 is useful for accident prediction by collecting data on accident sections and their causes from the accident section search system 12 and the accident cause diagnosis system 13.

 Each system content will be described in more detail.

Accident Detection and Accident Type Judgment (11) The accident detection and accident type judgment expresses the sensor information and the threshold value for the accident type judgment in a frame, and performs detection and judgment based on the frame data and the accident type judgment rule. Table 1 shows an example of the sensor information frame. In addition, even if the same sensor information is used, the threshold value may be different depending on the type of accident and the type of accident, and the threshold value for each is expressed using different slots. Second
The table shows an example of the accident type determination rule.

Table 1 Sensor information frame (FS (ako (value (BS))) (I _0s (default (0.5))) (I _b0s (default (0.3))) (V _c0s (default (100))) (V _b0s (default (50))) ( V d0s (default (200))) (φ s (range (-60 120))) (I as (default (2000))) (I bs (default (2000))) ( I _cs (default (2000))) (I _das (default (400))) (I _dbs (default (400))) (I _dcs (default (400))) (FS1 (ako (value (FS))) (I ₀ (value (0.04))) (V ₀ (value (30))) (V _c0s (value (90))) (φ (value (20))) (I _a (value (400))) ( I _as (value (1500))) (I _b (value (400))) (I _bs (value (1500))) (I _c (value (400))) (I _cs (value (1500))) (FS2 (ako (value (FS ))) (I 0 (value (0.01))) (I 0s (value (0.4))) (V 0 (value (20))) V c0s (value (80) ) (Φ (value (20) )) (I a (value (550))) (I as (value (1800))) (I b (value (550))) (I bs (value (1800))) (I _c (value (550))) (I _cs (value (1800)))) (KS (ako (value (FS))) (I _0s (default (0.4))) (I _b0s (default (0.2) )) (V _c0s (default (80))) (V _b0s (default (40))) (V _d0s (default (200))) (φ _s (range (−60 120))) (I _as (default ( 1800))) (I _bs (default (1800))) (I _cs (default (1800))) (I _das (default (200))) (I _dbs (default (200))) (I _dcs (default ( 200)))) (KS1 (ako (value (KS))) (I ₀ (value (0.01))) (I _0s (value (0.4))) (V ₀ (value (20))) (V _cos ( value (80))) (φ (value (20))) (I _a (value (350))) (I _as (value (1300))) (I _b (value (350)))) (I _bs (value (1300)) ) (I _c (value (350))) (I _cs (value (1300)))) (KS2 (ako (value (KS))) (I ₀ (value (0.01)))) (I _0s (value (0.4 ))) (V ₀ (value (20))) V _c0s (value (80))) (φ (value (20))) (I _a (value (300))) (I _as (value (1200)) ) (I _b (value (300))) (I _bs (value (1200))) (I _c (value (300))) (I _cs (value (1200)))) where I ₀ : zero phase Current current value I _os : Zero-phase current ground fault threshold I _bos : Zero-phase current minute ground fault threshold V ₀ : Zero-phase voltage current value V _c0s : Zero-phase voltage ground fault threshold V _b0s : Zero phase Voltage micro ground fault threshold V _d0s : Zero-phase voltage disconnection threshold φ: Current phase angle φ _s : Current phase angle threshold I _a : Current a phase current I _as : Current a short circuit threshold I _b : Current b-phase current value I _bs : Short-circuit threshold value of b-phase current I _c : Current value of c-phase current I _cs : Short-circuit threshold value of c-phase current I _das : Threshold value of disconnection of a-phase current I _dbs : b-phase Current Line Threshold I _dcs: c-phase current disconnection threshold FS, FS1, FS2, KS, KS1, KS2 is a frame name. The meaning of each signal is as follows.

ako: kind (a kind of) value: slot value (slot value) default: default value (default value) range: range that data can take Table 2 Accident Type Judgment Rules Rule 1) If _I0 is _{I0s in the} sensor SX If V ₀ is _greater than or _equal to V _c0s and the phase angle is within the phase angle threshold, it is a ground fault.

Rule 2) if and phase angle in the sensor SX I ₀ is and I ₀ is and V ₀ is V _B0s more is less than V _C0S V ₀ or I _B0s less than I _{0 s} is the phase angle within a threshold if This is a micro ground fault.

Rule 3) if the sensor SX in I _a is if a, b-phase two-wire short-circuit fault in the and I _b is I _bs more than I _{the as.}

Rule 4) if and I _c is I _b by the sensor SX is I _bs above is I _cs or more at if b, c-phase two-wire short-circuit fault.

Rule 5) If I _c is _{equal to} or greater than I _cs and I _a is _{equal to} or greater than I _{as in the} sensor SX, it is a c, a two-wire short circuit accident.

Rule 6) if the sensor SX in I _a is I _b is and I _o is if 3-wire short-circuit fault or more I _os or more I _bs above I _{the as.}

Rule 7) If V ₀ is _{equal to} or more than V _d0s with the sensor SX, it is a disconnection accident.

Frame representation is a form of knowledge representation proposed as a framework for modeling the processes of human memory and cognition.
It is one of the structural expressions of knowledge.
It is intended to efficiently understand specific situations, phenomena and objects, and solve problems efficiently, using conceptual descriptions of objects and the description of hierarchical relationships between them.

The most basic data structure of the frame representation is defined as follows.

<Frame> :: = <frame name><slot> ... <slot> That is, a frame is defined as a set of a frame name and a slot.

A slot is represented by a slot name and a slot value as follows, and the slot value is represented as follows.

<Slot> :: = <slot name><slotvalue><slotvalue> :: = <numerical value> | <character string> | <frame name> | <procedure name> | others where "|" Or "".

In the hierarchical relation between frames defined by the slot value, “a kind of”, “an instance of”, “a subs
The “is a” relationship such as “et of” has a property of inheriting the property, and the lower frame can inherit the property of the upper frame.

The basis of inference in the frame system is to determine the value of a slot whose value is unknown for the frame of interest.

As described above, in the frame, when the value of the slot is unknown, it is basically based on inheriting the property of the upper frame, but when that is not possible, an alternative method for determining the value of the slot is used. And a descriptor for it is required.

Regarding the value of the slot, when the type of data, the range that the data can take, and the value are unknown, the value is implicitly assumed unless there is a contradiction. This is called a default value. Various similar descriptors are required for expression.

To that end, many frame systems introduce subslots called facets.
The general data structure of a slot in which a facet is introduced is as follows.

<Slot> :: = <slot name> <facet> <facet value> ... <facet> <facet value> The following are typical facets.

(1) value facet: represents a value of a slot.

(2) data-type facet: indicates the data type of the slot.

(3) range facet: represents the range that the slot value can take.

(4) default facet: represents the default value of the slot.

When protecting and diagnosing the distribution system, it is usually sufficient to sequentially monitor the sensors TS on the power supply side of the substation. If an abnormality is detected in the TS sensor at the time of the accident, the BS and FS sensors below it may be checked. To represent the hierarchical structure of such a sensor, a frame as shown in Table 3 is used. Therefore,
In actual operation, extract the TS sensor name described at the beginning of the struct slot of the Net frame, read the necessary data from the frame storing the sensor information,
Activate the accident type determination rule. If this sensor is not determined to be abnormal, the frame data of the next TS sensor is read and the accident type determination rule is activated. If there is no list of sensors to be checked, return to the first TS sensor and repeat the same process. When an accident is detected, the accident type determination rule is similarly activated for the lower sensor BS. In this way, if the feeder in which the accident has occurred is determined as a result of sequentially examining the state of each of the TS, BS, and FS sensors, the accident type and the name of the feeder in which the accident has occurred are determined by the accident search system. Hand over to

 Table 3 Frame representation of sensor hierarchical structure (Net (struct (value (TS1 TS2))))) (TS1 (struct (value (BS1 BS2))))) (BS1 (struct (value (FS1 FS2 FS3)))) (BS2 (struct (value (FS4 FS5 FS6)))) (TS2 (struct (value (BS3 BS4))))) (BS3 (struct (value (FS7 FS8 FS9))))) (BS4 (struct (value (FS10 FS11) FS12)))) The meanings of the symbols are as follows.

Net: Frame name representing the entire substation sensor struct: Slot name meaning the structure The threshold for determining the type of accident is determined in consideration of the line constant, sensitivity coordination between the upper and lower sensors, and the like. In addition, an artificial ground fault test or the like must be performed to determine the line constant, which is very troublesome. Therefore, as in the case of a power outage, the power distribution system may change, or in the case of a newly installed power distribution system, the line constant may not be known. However, a threshold is required in the event of an accident.

In order to cope with such a case, if there is no sensor threshold value, the problem is solved by reading the default value of the same layer. If there is no default value at the same level, the default value at a higher level is read. In fact, as shown in Table 1, when the sensor FS1 no zero-phase current threshold _{I 0s (ako (value (FS} ))) zero sequence than the frame FS current threshold I default value of _0s See If there is no designation in the frame FS, the upper frame BS is referred to.

Accident section search (12) In the accident detection and accident type judgment, the accident type and accident feeder name were found. The search may be performed using information from the switch KS sensor connected to the accident feeder and the PS sensor of the telephone pole. The accident section search is performed according to the sensor information frame shown in Table 1 and the accident section search rule shown in Table 4.

However, it takes time to search the entire tree connected to the feeder. Therefore, an efficient accident search is performed based on the accident type determined by the host system. For example, in the ground fault accident search, the branch point can determine whether the accident is on the power supply side of the branch or at which branch on the load side.

Further, in an arbitrary section, it can be determined whether the accident has occurred on the power supply side or the load side in the section. In the short-circuit fault search, it is possible to determine at the branch point whether the fault has occurred on the current side of the branch or at which branch on the load side. It can be determined in which of the cases occurs. In the event of a disconnection accident, it is sufficient to preferentially search for a tree in which the zero-sequence voltage on one of the distribution line terminals and the power supply side is different. If the zero-sequence voltage on either end of the distribution line and the power supply side does not change much, the line current detection method is used to determine where the zero-phase impedance on the power supply side and the zero-phase impedance on the load side do not change much from the accident section. What is necessary is to search with priority.

In order to perform such an efficient search, the structure relating to the feeder and the switch is considered as a graph as shown in FIG. 4 and is represented as a frame as shown in Table 5. For example, the frame of the sensor KS3 in Table 5 has a sensor FS1 as a parent tree, sensors KS5 and KS9 at a lower branch point as a child tree, a sensor KS3 as a top node in the tree, and a sensor KS4 as an end node. The points on the branch include the sensors KS3 and KS4 and the end nodes of the tree, that is, the sensors KS8 and KS12 at the ends of the tree. Also, slots KS8, KS12, KS18, KS2 are used to represent trees from the distribution line end to the power supply side for searching for breaks.
In addition, there is a line current as a slot to be searched for preferentially when the zero-phase current on the power supply side does not change at any distribution line end.

In any of the above ground fault, short circuit, and disconnection accidents, in an arbitrary section, a binary search is an efficient method for determining whether the accident has occurred on the power supply side or the load side in that section.

The method of determining an accident section by the dichotomy will be specifically described with reference to FIG. In the figure, when a tree connected to the sensor FS7 is considered, for example, if an accident occurs between KS22 and KS23, first, the KS2 near the center of the tree as viewed from the whole tree
Refer to 3,24 sensors. In this case, it can be seen that the accident is closer to the power supply than KS23.

Next, referring to the sensors of FS7 and KS22, it is found that it is on the load side of KS22. Then, referring to KS22 and KS23, the accident section is determined.

This method is applied when there are no or few branches in the distribution line or when the distribution line is long.First, pay attention to the middle of the tree, and halve the section where the accident is considered to have occurred. Limited. By further dividing the half-limited section into two, the half is limited to one-fourth of the half. Thus, the search can be efficiently performed by sequentially limiting the sections to half.

As described above, the search is performed efficiently by incorporating the tree structure of the sensor into the knowledge of the accident section search rule.

Table 1 1 Accident search rules (in case of ground fault) Rule 1) If the fault type is determined as the ground fault in the accident type determination, the end node of the frame FS of the feeder determined to be ground fault and the child tree accident See the search frame.

Rule 2) If the accident search frame of the end node and the child tree is referenced, and the phase angle of the end node is not within the phase angle threshold value (the ground fault direction is the power supply side), and all phases of the child tree If the angle is not within the phase angle threshold (ground fault direction is the power side), see the first and next list of points on the branch.

Rule 3) If the accident search frame of the end node and the child tree is referenced, and the phase angle of the end node is within the phase angle threshold (the ground fault direction is the load side), and all phases of the child tree If the angle is not within the phase angle threshold (ground fault direction is the power supply side), the fault section is determined, and the fault section is the section surrounded by the end node and the child tree sensor.

Rule 4) If the accident search frame of the end node and the child tree is referred to, and the phase angle of the end node is within the phase angle threshold (the ground fault direction is the load side), and any phase of the child tree If the angle is within the phase angle threshold (the ground fault direction is on the load side), the end node of the frame of the child tree whose child's phase angle is within the phase angle threshold and the child tree accident search frame See

Rule 5) If the accident search frame of the list on the branch is referenced and the phase angle of the first list referenced on the branch is within the phase angle threshold (the ground fault direction is the load side) and the branch If the list phase angle after the above reference is not within the phase angle threshold (ground fault direction is the power supply side), the fault section is determined, and the fault section is surrounded by the sensors in the referenced list. In the section.

Rule 6) If the reference list on the branch refers to the accident search frame, and the reference list on the branch has a phase angle within the phase angle threshold (ground fault direction is the load side) and the branch If the above-referenced list after the phase angle is not within the phase angle threshold (the ground fault direction is on the load side), the list of the currently referenced list and the list of the currently referenced list See the following list.

Table 4-2 Accident search rules (in case of short circuit) Rule 1) If it is judged as short circuit by accident type judgment, the accident search frame of the end node and the child tree of the frame FS of the feeder frame judged as short circuit accident Please refer.

Rule 2) If the accident search frame of the end node and the child tree is referenced and the current of two or more phases of the end node is less than the short-circuit threshold, and the current of two or more phases of all child trees is short-circuited If it is below the threshold, see the first and next list of points on the branch.

Rule 3) If the accident search frame of the end node and the child tree is referenced and the current of two or more phases of the end node is equal to or more than the short-circuit threshold, and the current of two or more phases of all child trees is short-circuited If it is below the threshold, the accident section is determined, and the accident section is the section surrounded by the end node and the child tree sensor.

Rule 4) If the accident search frame of the end node and the child tree is referred to, and the current of two or more phases of the end node is greater than the threshold value, and the current of any two or more phases of the child tree is short-circuited If it is above the threshold, refer to the end node of the child tree frame and the child tree accident search frame where the current of two or more phases of the child tree is above the short circuit threshold.

Rule 5) If the currents of two or more phases in the first list referencing the branch on the branch are above the short circuit threshold and refer to the accident search frame in the list on the branch If the current of two or more phases in the list is less than the short circuit threshold, the fault section is determined, and the fault section is in a section surrounded by the sensors in the referenced list.

Rule 6) If the current of two or more phases in the first list that refers to the branch on the branch is greater than the short-circuit threshold and refers to the accident search frame in the list on the branch. If the current of two or more phases in the list is above the short-circuit threshold, refer to the list after the current reference and the list following the list after the current reference.

Table 4-3 Accident search rules (in case of disconnection) Rule 1) If the disconnection is determined in the accident type determination, refer to the frame FS of the feeder determined to be the disconnection accident and the last end node of the frame FS.

Rule 2) If the difference between the zero-sequence voltage of the frame FS of the feeder and the zero-sequence voltage of any of the last end nodes is 100 V or more, if the frame FS of the feeder and the final end node of the frame FS are referred to Refer to the first list of slots at the last end node where the difference between the zero-sequence voltage of the frame FS and the zero-sequence voltage at any of the last end nodes is 100 V or more, and the following list.

Rule 3) If the difference between the zero-sequence voltage of the frame FS of the feeder and the zero-sequence voltage of any of the last end nodes is less than 100 V, if the frame FS of the feeder and the final end node of the frame FS are referred to FS
And the final-node zero-phase voltage is 850V
If so, please refer to the first list of line current detection slots in frame FS of the feeder.

Rule 4) If the difference between the zero-sequence current in the first list and the zero-sequence current in the next list referring to the slot at the last end node is 100 V or more, the accident section is determined and the accident section is It is in a section surrounded by the sensor of the first list to be referred to and the sensor of the next list.

Rule 5) If the difference between the zero-sequence current in the first list that refers to the slot at the last end node and the zero-sequence current in the next list is less than 100 V, the list after the current reference See the next list in the list after the one you are currently referring to.

Rule 6) If the list of slots for line current detection is referenced and any of the interphase currents in the list of slots for line current detection is below the disconnection threshold, the fault section is determined and the fault section is referenced. It is in the section before the sensor in the list.

Rule 7) If the list of slots for line current detection is referenced and any of the interphase currents in the list of slots for line current detection is greater than or equal to the disconnection threshold, refer to the next list currently referenced. do it.

Table 5 Frame representation of sensor arrangement (FS1 (parent tree (value (BS1))) (child tree (value (KS3 KS13))) (top node (value (FS1))) (end node (value (KS2) ))) (Point on branch (value (FS1 KS1 KS2))) (final end node (value (KS8 KS12 KS18 KS2
1))) (KS8 (value (FS1 KS1 KS2 KS3 KS4 KS5 KS6 KS7 KS
8))) (KS12 (value (FS1 KS1 KS2 KS3 KS4 KS9 KS10 KS11 K
S12))) (KS18 (value (FS1 KS1 KS2 KS13 KS14 KS15 KS16 KS1
7 KS18))) (KS21 (value (FS1 KS1 KS2 KS13 KS14 KS15 KS19 KS2
0 KS21))) (Line current detection (value (KS3 KS4 KS5 KS9 KS13 KS14 KS1
5)))) (KS3 (parent tree (value (FS1))) (child tree (value (KS5 KS9))) (top node (value (KS3))) (end node (value (KS4))) (Point on branch (value (KS3 KS4))) (final end node (value (KS8 KS12)))) (KS5 (parent tree (value (KS3))) (child tree (value (ni1))) ( (Top node (value (KS5))) (End node (value (KS8))) (Point on branch (value (KS5 KS6 KS7 KS8))) (Last end node (value (KS8)))) (KS9 (parent Tree (value (KS3))) (child tree (value (ni1))) (top node (value (KS9))) (end node (value (KS12))) (point on branch (value (KS9 KS10) (KS11 KS12))) (Last End Node (value (KS12)))) (KS13 (Parent Tree (value (FS1))) (Child Tree (value (KS16 KS19))) (Top Node (value (KS13) )) (End node (value (KS15))) (point on branch value (KS13 KS14 KS15))) (final end node (value (KS18 KS21)))) (KS16 (parent tree (value (KS13))) (child tree (value (ni1))) (top node (value (KS16))) (end node (value (KS18))) (point on branch (value (KS16 KS17 KS18))) (final end node (value (KS18)))) (KS19 (parent tree (value (KS18)) (KS13))) (Tree of child (ni1))) (Top node (value (KS19))) (End node (value (KS21))) (Point on branch (value (KS19 KS20 KS21))) (Final end Node (value (LS21)))) Here, we consider that the whole distribution line tree is divided into small trees at branch points. Top node: Slot name representing the sensor on the most power supply side of the divided tree End contact: Split Slot name representing the sensor on the most load side of the tree Final end node: Slot name representing the sensor at the end of the distribution line nil: Applicable sensor Which means that there is no.

For example, if a ground fault occurs between KS14 and KS15,
According to the accident search rules shown in Table 4, first, the accident search frames KS2, KS3, and KS13 are referred to by rule 1). Next, rule 4) is activated and the accident search frames KS15, KS16, KS19
Is referred to. Next, rule 2) is activated, and KS13, KS14
Is referred to. Next, rule 6) is activated, KS14, KS15
Is referred to. Next, rule 5) is activated, and an accident between KS14 and KS15 is determined.

When a short circuit accident occurs between KS14 and KS15, the accident search frames KS2, KS3, and KS13 are referred to according to rule 1). Next, rule 4) starts, and the accident search frame KS15,
Reference is made to KS16 and KS19. Next, rule 2) is activated,
Reference is made to KS13 and KS14. Next, rule 6) is activated and KS
14, KS15 is referenced. Next, rule 5) is activated and KS14
It is judged as an accident during KS15.

If the disconnection accident is between KS10 and KS11, first rule 1) is activated, and FS1 and KS8, KS12, KS18, KS21 are referred to. Next, rule 2) is activated, and FS1 and KS1 are referred to.

Next, rule 5) is activated, and KS1 and KS2 are referred to. Next, rule 5) is activated, and KS2 and KS3 are referred to. Next, rule 5) is activated, and KS3 and KS4 are referred to. Next, rule 5) is activated, and KS4 and KS9 are referred to. Then rule 5)
Starts, and KS9 and KS10 are referenced. Next, rule 5) is activated, and KS10 and KS11 are referred to. Next, rule 4) was activated and the accident section was determined.

If the zero-phase impedance on the power supply side and the zero-phase impedance on the load side do not change from the fault section, as in the fault section between KS3 and KS4, Rule 1) is activated and FS1
And KS8, KS12, KS18, KS21, then Rule 3)
Starts up and KS3 is referenced.

Next, rule 6) is activated and the section before KS4, that is, KS3
The accident section was decided between KS4.

If the disconnection point is between KS3 and KS4, the slots at the final end nodes are KS8 and KS12, but either slot may be searched. The result is the same regardless of which slot is searched.

The method of searching for an accident section when there is a branch in the accident section is as follows (see FIGS. 8 and 9).

○ In case of line current change (decrease) 1) If the next sensor is branched more than two, and if all the next sensors are abnormal, the one near the normal sensor from the branch point is the accident section.

2) When two or more branches following the normal sensor are branched, and when one of the next sensors is abnormal, the one closer to the abnormal sensor from the branch point is the accident section.

○ In the case of the difference in zero-phase voltage before and after the accident section, 3) When the sensor next to the P or M sensor is branched into two or more, and when all the following sensors are M or P, the power supply side from the branch point The section closer to is the disconnection accident section.

4) When the sensor next to the P or M sensor is branched into two or more, and one of the next sensors is M or P, a portion closer to the sensor from the branch point is a disconnection accident section.

According to such a method, a more detailed search can be performed.

Here, P represents the case where the zero-phase voltage is large, and M represents the case where the zero-phase voltage is small.

In the accident search including the sensor PS, after performing an accident section search using only the KS sensor, FS is replaced with KS and KS is replaced with PS in the above, or KS and PS are performed on the same rank.

The concept of the default value when there is no threshold value is the same as in the case of accident detection and accident type determination.

A specific method of accident detection, accident type determination, and accident section search will be described.

A sensor is provided for each of the distribution substation buses, distribution circuit breakers, sectional switches, and distribution lines divided by the circuit breakers and the sectional switches, etc., and information of these sensors is collected at one place through an information transmission network. Has a control system that searches for an accident section and issues an open / close command to a circuit breaker or a sectional switch to separate the accident section.The control system includes at least accident detection and accident type determination, accident section search, (1) For ground faults and short circuit accidents, the accident type determination system uses the zero-phase current, zero-phase voltage, phase angle, line current, etc. of sensors in the substation. Detected by signal, in the accident section search system, select an appropriate division point such as a branch point of the distribution line, determine its power supply side, load side, which branch side has an accident section, To explore the fault section by repeating the record.

(2) The 1 and 2 line disconnection accidents are detected by the accident type determination system by the signal of the sensor in the substation and by comparing the signal with the zero-phase voltage signal of the distribution line terminal sensor. In the search system, a tree having a difference between the zero-phase voltage signals of the substation sensor and the distribution line end sensor is searched with priority.

In particular, in the case of a single-line or two-line disconnection accident, when the accident section is located at the end of the distribution line, the zero-phase voltage on the power supply side is smaller than that in the accident section. Therefore, considering the detection sensitivity and residual voltage of the sensor, there is a possibility that an accident cannot be detected only by the substation sensor, and the detection can be reliably performed by comparison with the distribution line end sensor.

(3) Regarding the above items (1) and (2), for the 1-line and 2-line disconnection ground faults, the ground fault accident section is searched first by detecting the ground fault accident, and then the disconnection fault section is searched.

(4) For line 1, 2, and 3 line disconnection accidents, the accident type judgment system and accident section search system determine the accident type based on the changing tendency of the line current signals of the sensors in substations and distribution lines at various points in the system. And search for the accident section. In this case, it is preferable to search in order from the power supply side to the load side.

For example, in FIG. 4, TS1, BS1, FS1, KS1, KS2
・ ・ ・ ・ ・ In this order, KS20, KS21, FS2 ...
If a decrease in line current is observed, the section before the sensor is an accident section.

(5) In the event of a disconnection accident at the point where the zero-phase impedance on the power supply side and the load side in the accident section are approximately equal in the center of the distribution line system, the signal (line current) of the substation sensor and distribution line sensor in the system Search the accident section according to the changing tendency.

As described above, the accident type and the accident section can be accurately and efficiently determined.

Hereinafter, a method of comparing the detection values of the sensors at various points in the distribution line in the system to determine the accident section will be described.

(1) Judgment method for fault section in case of ground fault (direction comparison method) (a) As shown in Fig. 6 (a), when both ground fault directions at the dividing points on both sides of the track section are in the load side direction , That section is not an accident section. Therefore, the section on the load side is further determined.

(B) As shown in FIG. 6 (b), when the ground fault direction is different in the section points on both sides of the track section, the section is determined to be an accident section.

(C) As shown in FIG. 6 (c), in the multi-branch circuit,
When the power supply side and the load side are in the same direction, the power supply side and the load side are in the different directions, and the power supply side and the load side are in the different directions, it is determined that there is an accident on the load side further on the load side in the accident section.

(D) As shown in FIG. 6 (d), in the multi-branch circuit,
When the power supply side and the load side are in different directions, it is assumed that the accident section is the section.

(2) Method of judging an accident section in the event of a short circuit accident (detection value vs. set value comparison method) A method of detecting a short circuit accident and a setting method in each sensor are as follows, for example.

The overcurrent set value shall be 150% of the maximum load current at each point. Here, the maximum load current refers to a value obtained by adding the maximum load current to the adjacent line to the annual maximum load current.

The overcurrent set value at the terminal may be set to be equal to or less than the terminal minimum short-circuit current × 75%. This is not an absolute requirement.

The accident determination based on the detection information at each point will be described with reference to FIG. In the drawing, P indicates a case where the detected value is equal to or larger than the set value, and M indicates a case where the detected value is equal to or smaller than the set value.

(A) As shown in FIG. 7 (a), when the power supply side is sequentially followed from the load side and changes from P to M, it is determined that there is an accident between P and M.

(B) As shown in FIG. 7 (b), even if the power supply side is M, it becomes P in the middle, and when it changes from P to M, the P and M
It is determined that there is an accident between the two.

(C) As shown in FIG. 7 (c), when there is a branch point, if there is P after the branch point and it changes to M, it is determined that there is an accident between P and M.

(D) As shown in FIG. 7 (d), when there is a branch point, if P is before the branch point and M is all after the branch point, it is determined that there is an accident at the branch point.

 In summary, i) There is an accident section on the load side from P.

ii) If there is P on the load side even for M, it is after that.

iii) If the next section is branched into two or more sections, the accident section is on the side with P (in the case of a single accident). In the case of all M, it is in the branching section.

(3) fault section determination method in the case of accidental disconnection (line current detection method) the load side of I _a of fault section, I _b, utilized to break intervals that decrease or abnormally not flow either I _c is Is determined. For example, as shown in FIG. 8 (a), the line current shows a normal value (represented by a symbol N) on the power supply side from the fault point, and no current flows or an abnormal value (represented by the symbol D) on the load side. Show. The point that changes from N to D is the accident section.

If there is an accident around the junction, Fig. 8 (b),
When one side of the branch changes from N to D as in (c), the branch section on the changing side is the accident section.

When both branch sides change to D as shown in FIG. 8 (d), the branch section from the branch point to the power supply side is an accident section.

To summarize: 1) If there is an abnormal sensor next to the normal sensor, the section between the normal sensor and the abnormal sensor is the accident section.

2) When there are two or more branches following the normal sensor, if one or more of the sensors has an abnormality, the section after the normal sensor is an accident section.

3) If there is more than one branch next to the normal sensor, and if all the next sensors are abnormal, the accident section is closer to the normal sensor from the branch point.

4) When there is more than one next to the normal sensor, and when one of the next sensors is abnormal, the one closer to the abnormal sensor from the branch point is the accident section.

Note that in this case, if the inductive load is large,
Current continues to flow to the disconnection load side due to the back induced voltage, and N
Since the distinction between D and D is not always clear, it is not reliable with this method to detect a disconnection or determine a section.

(4) fault section determination process (zero-phase voltage detection system) in the case of accidental disconnection V ₀ is generated when disconnected. However, since the zero-phase impedance is not known, it cannot be calculated in practice. However figures V ₀ to the fault point to the boundary fault section is found by different. In this case, it determines the value of V ₀ at the power supply side and the load side by the position of the fault point to the overall distribution line by using the difference.

The zero-phase voltage V ₀ of the above 2) is given by the following equation.

However, V _OA1 is the zero-phase voltage in the case of one-wire break V _OA2 is the zero-phase voltage in the case of two-wire break E is the phase voltage Z _OB is the zero-phase impedance after the break point Z _OA is zero on the power supply side from the break point Phase impedance Zero-phase voltage V _{0 at the} terminal is given by the following equation.

However, V _OB1 is 1 line in case of disconnection zero-phase voltage V _OB2 is Z _OA a more zero-phase impedance of the power supply-side zero-phase voltage disconnection point for the two-wire disconnection, the zero-phase impedance of the load side and Z _OB, P, V ₀ when V ₀ is large
Is represented by M when is small.

(B) Assuming that _ZOA : _ZOB = 1: 10 near the end of the distribution line, the voltage distribution is as shown in FIG. 9 (a). M on the power supply side at the fault point, P on the load side
And the point where M changes to P is the accident section.

(B) Assuming that _ZOA : _ZOB = 10: 1 at the power supply end of the distribution line, the voltage distribution is as shown in FIG. 9 (b). P on the power supply side, M on the load side,
The point that changes from P to M is the accident section.

(C) Assuming that _ZOA : _ZOB = 1: 1 at the center of the distribution line, the voltage distribution becomes uniform as shown in FIG. 9 (c), and the fault point cannot be determined. It is necessary to use other determination means together.

(D) When there is a branch other than the accident point, the determination can be made by the above (a) or (b). In the case of FIG. 9 (d), the determination is made in the same manner as in FIG. 9 (b).

(E) When there is a branch at the fault point, as shown in FIG.
_OA , Z _OB and Z
_This will be described below as _OC .

In FIG. 9 _{(e), Z OA: Z} OB: Z OC = 1: 1/10: shows the voltage distribution assuming 1/2. M on power supply side from distribution point, 1st
If the branch side is M and the second branch side is P, the first branch side branch section that changes from P to M is the accident section.

(F) In the case of FIG. 9 (f), the power supply side is P,
The first branch side is M, the second branch side is M, and the branch section on the power supply side from the branch point is the accident section. (G) In the case of FIG. 9 (g), the power supply side from the branch point is M,
The first branch side is M, the second branch side is P, and the branch section on the second branch side is the accident section.

As described above, when there is a branch as in (e) to (g), the section is divided around the branch, and the accident section has a different numerical value.

To summarize the above, 1) If there is a sensor indicating M or P next to a sensor indicating P or M, a section between them is a disconnection accident section.

2) If the sensor next to the P or M sensor is branched into two or more, and if all of the next sensors are M or P, the one closer to the power supply side from the branch point is the disconnection accident section.

3) When the sensor next to the P or M sensor is branched into two or more, and when one of the next sensors is M or P, the one closer to the sensor from the branch point is the disconnection accident section.

Until now, it was explained by performing accident detection and accident type judgment and accident section search using a knowledge engineering approach.
It is also possible to carry out with a conventional procedural algorithm.
For example, accident detection is performed according to a flowchart as shown in FIG.

Diagnosis of accident cause (13) The waveform of zero-phase current or zero-sequence voltage differs depending on the cause of the accident. In addition, since the waveform is slightly different due to line impedance, ground capacitance, ground fault resistance, and the like, it is difficult to describe a diagnostic rule in a normal production system.

Therefore, in a system as shown in FIG. 2, the degree of involvement of each input data in the accident determination is expressed in a fuzzy manner,
Inference based on this enables the diagnosis of the cause of the accident, and also provides flexibility for correction and change. In the waveform analysis, the waveforms of the zero-phase voltage and the zero-phase current are decomposed into an integrated distortion factor, a DC component, a harmonic component, and the like.

In FIG. 2, an accident waveform input step 21, a waveform analysis step
22, Fuzzy expression process 23 of the degree of accident involvement of each element, Inference process 24 using production rules, Accident cause diagnosis process 2
5. An inference step 26 using a conventionally used procedural program and an inference step 27 using a fuzzy expression of evaluation results. The part obtained by combining the steps 23, 24 and 27 belongs to the fuzzy inference F in general, and can be referred to as fuzzy inference F as a general expression.

 In addition, as a diagnosis method, in addition to the A route (31 → 32 → 33 → 34 → 35), the B route (31 → 32 → 33 → 37 → 35) and the C route (31 → 32 → 34 → 35) ), D route (31 → 32 → 33 → 36 → 35), E route (31 → 32 → 36 → 35), F route (31 → 32 → 34 → 37 → 35).

These can be selected at any time depending on the complexity of the accident phenomenon. When the accident phenomenon is simple, the diagnosis processing becomes simpler and faster as A → E. → If the version is not upgraded to A, the diagnosis process will be erroneous or difficult. The F route is equivalent to the B route.

FIG. 3 shows an example of a fuzzy expression relating to the degree of accident involvement from the waveform analysis result in step 22 in step 23.

Here, S _HVG the insulator accident involvement of the membership function of the defective during zero-phase voltage integrated strain rate, S _HVJ is a membership function of an accident involving a degree of zero-phase voltage integration distortion during tree contact, vertical The axis is the value of the membership function, and the horizontal axis is the value of the precondition.

Similarly, a fuzzy expression regarding the degree of accident involvement is made for the integrated distortion factor of the zero-phase current, the DC component of the zero-phase current, and the DC component of the zero-phase current. Table 6 shows the membership functions.

The membership function of the fuzzy coefficient can have a normal distribution if the number of data is large, but it is generally difficult to collect a large amount of data, and the margin of judgment is quite large. Not so necessary, an approximation is sufficient. In this case, it is represented by a chevron triangle.

Next, an accident possibility evaluation function for each accident cause is defined as the sum of the membership functions related to the accident involvement degree. _{That, f g = S hvg + S} hig + S dvg + S dig ...... (1) f j = S hvj + S hij + S dvj + S dij ...... (2) by using this, the production rule as shown in Table 7, Diagnose the cause of the accident.

If such a method is used, in the case of a micro-ground fault or the like, it becomes possible to predict an accident before the circuit breaker of the substation develops into an accident.

The above formulas (1) and (2) show an example of the evaluation function. As another example, weighting can be performed.
_{That, f g '= k 11 S} hvg + k 12 S hig + k 13 S dvg + k 14 S dig ...... (3) f j' = k 21 S hvj + k 22 S hij + k 23 S dvj + k 24 S dij ...... ( 4) _{where, k 11 ~k 14, k 21} ~k 24 is the coefficient of the weighting.

The way to determine these coefficients is determined by experimentation to suit the actual situation. In addition, various definitions of the evaluation function can be selected according to the actual situation such as a simulation result.

The above expressions (3) and (4) are general expressions of the evaluation function, but the expression of the evaluation function is not limited to this. In addition, the expressions (1) and (2) and the individual membership functions are derived from the expressions (3) and (4) in a manner of counting the weights, and are each considered to be a kind of an evaluation function. Can be generally expressed as an “evaluation function”.

In the above, when using a production rule, a rule (rule) can be set in such a manner that information is used effectively. The model is then grown from the perspective of how well the model fits in reality or how easy it is to make it closer to human judgment. In that case, considering a fuzzy rule-type model, if the number of rules is not so large, specifically, if it is only several dozen, the fuzzy inference method can be applied well in the field. The production rule using fuzzy is characterized in that it essentially narrows down to a small number of rules.

In a normal production system of, for example, an expert system, the number of rules is large. Because, in the expert system, since it is represented by a threshold, it is divided somewhere, and the boundary becomes a contact point. This is because, if flexibility is to be provided in order to prevent this, one parameter is divided into a large number by a threshold value and rules are applied to each parameter, thereby increasing the number of rules.

Accident frequency data collection (24) By collecting accident frequency data of accident sections and their causes, it is possible to predict the risk of micro-ground faults and the occurrence of accidents, and to predict lightning. Specifically, in the case of a micro ground fault due to a cable, etc., about ten micro ground faults may be detected within about 10 minutes, and collecting accident frequency data is useful for preventive maintenance.

〔The invention's effect〕

 The present invention has the following effects by the above configuration.

Since the accident diagnosis method of the present invention is structured such that the four small systems of accident detection and accident type determination, accident section search, accident cause diagnosis, and accident frequency data collection are hierarchized by function, knowledge construction and verification, Modification is easy.

Since the accident detection and the accident type judgment are performed according to a predetermined judgment rule using predetermined information from among sensor information of various parts of the distribution line, quick and accurate judgment can be made.

The accident section search uses the sensor information of each part of the distribution line,
At the midway point of the distribution line, it is determined whether the accident section is on the power supply side or the branch side of the load side, and this is repeated to search for the accident section, or Comparing signals at each location with each other to extract and possibly search for a sequence that may include an accident section, or compare signals at various locations within the distribution line system to search for changes in the system The search can be performed efficiently and quickly.

Before shutting down the distribution circuit breaker (bank breaker, feeder breaker), the accident type judgment, accident section search and accident cause diagnosis are performed in a short time, and the switch related to the accident section is opened and closed, and the healthy section The accident section can be separated without power outage.

By detecting an accident and judging the type of accident by the sensor information frame and a predetermined judgment rule, and searching for an accident section by a predetermined search rule, accident detection and
Accident section search can be performed accurately and quickly.

In the accident cause diagnosis, each element of the waveform data is expressed in a fuzzy expression, and the cause of the accident can be accurately and quickly diagnosed by inference based on the elements.

Accident frequency data collection enables uncertain accident phenomena, such as intermittent ground faults and incomplete ground faults, to be identified, to prevent accidents that may develop into future ground faults, and to prevent accidents. did.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a system configuration of the present invention;
FIG. 2 is a block diagram of the accident cause diagnosis system according to the present invention, FIG. 3 is an explanatory diagram showing a fuzzy expression of the degree of accident involvement,
FIG. 4 is a power distribution system diagram, FIG. 5 is a configuration diagram in which the arrangement of sensors installed in the power distribution system of FIG. 4 is represented in a graph, and FIGS.
FIG. 9 is an explanatory diagram illustrating various accident section determination methods, and FIG.
The figure is a flowchart of accident detection.

Continuation of the front page (56) References JP-A-60-216732 (JP, A) JP-A-58-86825 (JP, A) JP-A-59-47923 (JP, A) JP-A-59-94018 (JP) , A) JP-A-59-59015 (JP, A) JP-B-49-34098 (JP, B1) "Protection control method based on distribution system multipoint information (part 2)-Operation algorithm by system recognition method", Report of Central Research Institute, NO. TZ6070 (July 1987), Yukihira, et al. Haruki Ueno, "Expert System-Knowledge Engineering and Its Applications-" (December 25, 1986) Ohmsha, P.S. 47-70J. KIM and B. DON R USSELL, "Harmonia Behavior dueling Arcing Faults on Power Distribution Feeders", Electric Power Systems Reservation, Vol. 14 (1988), no. 3, p. 219−225

Claims (12)

(57) [Claims] A sensor is provided for each of a distribution substation bus, a distribution circuit breaker, a section switch, and distribution lines separated by the circuit breaker, the section switch, and the like, and information of these sensors is transmitted through an information transmission network. It has a control system that collects data at one location, searches for accident sections, and issues switching commands to circuit breakers and sectional switches to separate accident sections.The control system includes at least accident detection and accident type judgment. A distribution line accident diagnosis method, which is hierarchized into a small system for searching for an accident section and diagnosing an accident cause. 2. The distribution line fault diagnosis method according to claim 1, wherein a small system for collecting fault frequency data is added to the control system in a hierarchical manner. 3. A ground fault fault and a short circuit fault are detected in a small fault type determination system by using a zero-phase current of a sensor in a substation.
Detected by signals such as zero-phase voltage, phase angle, line current, etc., in the fault section search system, select an appropriate section point such as a branch point of the distribution line, and select the fault section on the power supply side, load side, or any branch side. 3. The distribution line fault diagnosis method according to claim 1, wherein it is determined whether or not there is, and the fault is repeatedly searched for the fault section. 4. A single-wire or two-wire disconnection accident is detected by a signal from a sensor in a substation and a comparison between the signal and a zero-phase voltage signal from a terminal sensor of a distribution line in a small accident type determination system. 3. The distribution line fault diagnosis according to claim 1, wherein in the fault section searching small system, a tree having a difference between the zero-phase voltage signals of the substation sensor and the distribution line terminal sensor is preferentially searched. Method. 5. In the case of the single-line and two-line ground faults, when the fault detection and accident type determination small system detects a ground fault and a disconnection accident, the ground fault accident section is searched first, and then the ground fault accident is detected. The method according to any one of claims 1 to 4, wherein if a section is not known, a disconnection accident section is searched thereafter. 6. In the accident detection and accident type judgment small system and the accident section searching small system, regarding the line 1, 2, and 3 line disconnection accidents, in the substation and in the system of the line current signal of the sensor in each distribution line. 3. The distribution line accident diagnosis method according to claim 1, wherein the accident detection, the accident type judgment, and the accident section search are performed based on the change tendency. 7. In the event of a one-line or two-line disconnection accident, if there is not much difference in the zero-phase voltage between the sensor in the substation and the terminal sensor in the distribution line, an accident detection and accident type judgment small system and an accident section searching small system are integrated. 6. The distribution line according to claim 1, wherein the two systems detect an accident, determine an accident type, and search for an accident section based on a change tendency in a system of a line current signal of a sensor in a substation and various points in a distribution line. Accident diagnosis method. 8. If there is no significant difference between the zero-phase voltage of the sensor in the substation and the zero-phase voltage of the sensor at the end of the distribution line in a one-line or two-line disconnection accident, the zero-phase impedance on the load side and the zero-phase impedance on the power source in the accident section. 6. The distribution line fault diagnosis method according to claim 1, wherein priority is given to a zone in which the line current does not change much, and the fault zone is searched for based on a change tendency of the line current signal in the system. 9. The accident search and accident type judgment small system comprises:
9. The method according to claim 1, wherein the sensor information and the threshold value for determining the type of accident are represented by a frame, and the frame data and the rule for determining the type of accident are used to detect and determine the type of accident. The described distribution line accident diagnosis method. 10. An accident section searching small system uses a sensor information frame and an accident section searching rule incorporating a sensor tree structure into knowledge based on an accident type and an accident feeder name found by the accident type judging system. And judging an accident section.
The distribution line accident diagnosis method according to any one of the above items. 11. The fault section search system, when searching for a section of a break fault by a method of observing a change in line current, when two or more nodes following a normal sensor are branched at a branch point of a distribution line, all of the following: If one of the sensors is abnormal, it is determined that the area closer to the normal sensor from the branch point is the accident section, and if one of the next sensors is abnormal, the area closer to the abnormal sensor from the branch point is the accident section. 11. The distribution line fault diagnosis method according to claim 1, wherein the method has a rule. 12. An accident section search system for detecting an accident section of a disconnection accident by checking a difference in zero-phase voltage before and after the accident section.
When the next sensor of the P or M sensor is branched into two or more at the branch point of the distribution line, all the next sensors are M
In the case of P or P, the one closer to the power supply side from the branch point is the disconnection accident section, and if one of the sensors next to the P or M sensor is M or P, the one closer to that sensor from the branch point is broken. The distribution line fault diagnosis method according to any one of claims 1, 2, 5, and 9 to 10, further comprising a determination rule that the fault is a fault section.