Automatic trouble analysis apparatus and method thereof

• US 4,839,823 A
• Filed: 08/10/1988
• Issued: 06/13/1989
• Est. Priority Date: 03/20/1985
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Matsumoto, Yoshihiro
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): MELNICK, STEVEN A
• Application Number:
  US07/230,723
• Time in Patent Office: 307 Days
• Field of Search: 364/550, 364/551, 364/552, 364/554, 364/513, 364/492, 364/495
• US Class Current: 706/52
• CPC Class Codes: G05B 23/024 Quantitative history assessment, e.g. mathematical relationships between available data; Functions therefor; Principal component analysis [PCA]; Partial least square [PLS]; Statistical classifiers, e.g. Bayesian networks, linear regression or correlation analysis; Neural networks
• CPC Class Codes: Y10S 706/90 Fuzzy logic
• CPC Class Codes: Y10S 706/907 Power plant
• CPC Class Codes: Y10S 706/911 Nonmedical diagnostics

Abstract

In a trouble analysis apparatus, a cause of an accident which is empirically and statistically obtained, and a plurality of effects corresponding to the cause are entered in advance at a keyboard and stored as a data base in a magnetic disk unit. In this case, a sum of basic probabilities of the plurality of effects for the cause is set to be 1. A pre-processor calculates as upper (or lower) probability of a subset of the result by using the Dempster & Shafer probability theory. The pre-processor uses the upper or lower probability to create Fuzzy membership functions, and also creates a hypothetical proposition for corresponding the Fuzzy membership function and the cause. An inference engine matches accident phenomena with the effects when an accident occurs and infers the cause by a modified Fuzzy inference method using the hypothetical proposition.

Claims

1. An apparatus for monitoring an accident occurring in an electric power system including at least logical switches and protective relays, on the basis of a Dempster &

Shafer theory and a Fuzzy theory,

wherein, assuming that elements constituting a phenomenon occurring in the electric power system are Ai (i=1, 2, . . . ) which is a subset of a whole set A0={a1, a2, . . . an}, where a1, a2, . . . an represent states of logical switches or protective relays, the Dempster &

Shafter theory defines the following;

basic probability m(Ai) is ##EQU15## and, when relationship m(Ai)>

0 stands, lower probability P*(Ai) is ##EQU16## and upper probability P*(Ai) is ##EQU17## and, assuming that a whole set is U {u1, u2, . . . , un}, where ui (i=1, 2, . . . n) is any one of lower probability P*(Ai) and upper probability P*(Ai), and the Fuzzy set is F, the Fuzzy set defines the following;

##EQU18## where μ

F(ui) is the grade of ui in a membership function of U;

"/" is the separator and "+" means "or";

when propositions represented by

Compound Proposition;

if (X is F) then (y is G) and

Propositions;

(x if F'"'"') are given,

space="preserve" listing-type="equation">y is G'"'"'

space="preserve" listing-type="equation">for G'"'"'=F'"'"'o[(F×

G)∪

(F×

V)]

is inferred by the generalization of modus ponens, where each of F and F'"'"' is Fuzzy set in U and each of G and G'"'"' is Fuzzy set of V, which is a set of v1, v2, . . . vm, where vj (j=1, 2, . . . m) represents a cause of failure,

said apparatus comprising;

means for operating said electric power system in operating equipment types including

(1) Balanced-type dual-feeder system,

(2) Radial feeder system,

(3) Single feeder,

(4) Double bus,

(5) Single bus,

(6) Transformer,

(7) Center point grounding,

(8) Power-factor improvement and stabilizing equipment,

(9) 3-terminal balanced-type dual-feeder system, and

(10) 3-terminal single feeder;

first means for detecting operating conditions of said logical switches and said protective relays;

second means for creating a first list which lists, for each of said operating equipment types, cause/effect relationships including a plurality of causes of accidents that are empirically obtained, a plurality of effects associated with said causes, and basic probabilities of the respective effects, a sum of the basic probabilities being equal to 1;

for creating a second list which lists logical switches and protective relays whose operating conditions have changed during time period t1 after detection of an accident;

for creating a third list which lists logical switches and protective relays which are regarded as being associated with the accident among from those listed in said second list, when the occurrence of the accident is confirmed;

for determining an operating equipment type of said electric power system from the logical switches and protective relays that are listed in said third list, and creating a fourth list in which names of logical switches of facilities that are regarded as being associated with the accident are related with those of logical switches of the operating equipment type as determined;

for calculating any one of upper and lower probabilities for the cause/effect relationship listed in said first list, using the Dempster &

Shafer theory, and producing a membership function; and

for performing approximate reasoning by the use of the Fuzzy theory, on the names of the logical switches of the determined operating equipment type, using the membership function, to thereby infer facilities associated with the accident.

2. A method for monitoring an accident occurring in an electric power system including at least logical switches and protective relays, on the basis of a Dempster &

Shafer theory and a Fuzzy theory,

wherein, assuming that elements constituting a phenomenon occurring in the electric power system are Ai (i=1, 2, . . . ) which is a subset of a whole set A0={a1, a2, . . . an}, where a1, a2, . . . an represent states of logical switches or protective relays, the Dempster &

Shafer theory defines the following;

basic probability m(Ai) is ##EQU19## and, when relationshp m(Ai)>

0 stands, lower probability P*(Ai) is ##EQU20## and upper probability P*(Ai) is ##EQU21## and, assuming that a whole set is U {u1, u2, . . . , un}, where ui (i=1, 2, . . . n) is any one of lower probability P*(Ai) and upper probability P*(Ai), and the Fuzzy set is F, the Fuzzy set defines the following;

##EQU22## where μ

F(ui) is the grade of ui in a membership function of U;

"/" is the separator, and "+" means "or";

when propositions represented by

Compound Proposition;

if (X is F) then (y is G) and

Proposition;

(x is F'"'"') are given,

space="preserve" listing-type="equation">y is G'"'"'

space="preserve" listing-type="equation">for G'"'"'=F'"'"'o[(F×

G)∪

(F×

V)]

is inferred by the generalization of modus ponens, where each of F and F'"'"' is Fuzzy set in U and each of G and G'"'"' is Fuzzy set of V, which is a set of v1, v2, . . . vm, where vj (j=1, 2, . . . m) represents a cause of failure,

said method comprising;

a first step of operating said electric power system in operating equipment types including

(1) Balanced-type dual-feeder system,

(2) Radial feeder system,

(3) Single feeder,

(4) Double bus,

(5) Single bus,

(6) Transformer,

(7) Center point grounding,

(8) Power-factor improvement and stabilizing equipment,

(9) 3-terminal balanced-type dual-feeder system, and

(10) 3-terminal single feeder;

a second step of detecting operating conditions of said logical switches and said protective relays;

a third step of creating a first list which lists, for each of said operating equipment types, cause/effect relationships including a plurality of causes of accidents that are empirically obtained, a plurality of effects associated with said causes, and basic probabilities of the respective effects, a sum of the basic probabilities being equal to 1;

of creating a second list which lists logical switches and protective relays whose operating conditions have changed during time period t1 after detection of an accident;

of creating a third list which lists logical switches and protective relays that are regarded as being associated with the accident among from those listed in said second list, when the occurrence of the accident is confirmed;

of determining an operating equipment type of said electric power from the logical switches and protective relays that are listed in said third list, and creating a fourth list in which names of logical switches of facilities that are regarded as being associated with the accident are related with those of logical switches of the operating equipment type as determined;

of calculating any one of upper and lower probabilities for the cause/effect relationship listed in said first list, using te Dempster &

Shafer theory, and producing a membership function; and

of performing approximate reasoning by the use of the Fuzzy theory, on the names of the logical switches of the determined operating equipment type, using the membership function, to thereby infer facilities associated with the accident.