Fuzzy Logic Based Approach for Power System Fault Section Analysis

2. Literature Review

Over the last ten decades a larger number of papers have published in the area of fault section identification in power network. Here in this chapter, an attempt has been made review some of major contribution in this area.

(Zhu, Yang, Hogg, Zhang & Gao 1994) have described the development of an expert system for estimating fault section in control cEnter based on protective system simulation. They have presented as a principle for stable power supply, any fault sections in a power system must be disconnected quickly, to meet this principle, utilities are making effort to educate and train their operators for recovering power supply in proper manners. System operation and protective relay actions, but also accurate and extremely quick judgment based on the knowledge. Because of the importance of system restoration, development of an expert system efficiently supporting operators is eagerly awaited. Therefore, fault section judgment has been studied a some of the major themes in the field of artificial intelligence application to electric power systems .In many studies in this field, knowledge about cause and effect between the fault section and relay action is represented. There are many devices in power system and therefore, in order to describe a power system and its protective system accurately, a great numbers of consistent rules are required. This makes acquisition and verification of the knowledge difficult.

To overcome this problem, they proposed a method for estimating fault section including protective system simulation; the authors have developed a practical expert system which infers the protective coordination of relays on the bas is of the protection zone and time setting of the relays.

They proposed expert system features

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  Relay operation functions are represented by protection zone and time setting with numerical figures, which service as database provided outside the expert system.

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  The explanation facility of many other expert systems displays only the inference chain of rules applied, requiring the operators to comprehend the rules and their knowledge representation structure totally.

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  Separating teleological knowledge and non-teleological knowledge

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  Judgment for “single”, “multiple”, “phase to phase” and “phase to earth” as well as “malfunction” of relays, “failure to operate” of relays and circuit breakers.