Hindawi Publishing Corporation Discrete Dynamics in Nature and Society Volume 2014, Article ID 761507, 8 pages http://dx.doi.org/10.1155/2014/761507 Research Article Complexity Quantification for Overhead Transmission Line Emergency Repair Scheme via a Graph Entropy Method Improved with Petri Net and AHP Weighting Method Jing Zhou,1,2 Cunbin Li,2 Weihua Shen,3 and Ye Zhang1 1 School of Control and Computer Engineering, North China Electric Power University, Beijing 102206, China 2School of Economics and Management, North China Electric Power University, Beijing 102206, China 3State Grid Shanxi Electric Power Company, Taiyuan 030001, China Correspondence should be addressed to Jing Zhou; [email protected] Received 22 September 2014; Revised 4 December 2014; Accepted 9 December 2014; Published 21 December 2014 Academic Editor: Muhammad Naveed Iqbal Copyright © 2014 Jing Zhou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. According to the characteristics of emergency repair in overhead transmission line accidents, a complexity quantification method for emergency repair scheme is proposed based on the entropy method in software engineering, which is improved by using group AHP (analytical hierarchical process) method and Petri net. Firstly, information structure chart model and process control flowchart model could be built by Petri net. Then impact factors on complexity of emergency repair scheme could be quantified into corresponding entropy values, respectively. Finally, by using group AHP method, weight coefficient of each entropy value would be given before calculating the overall entropy value for the whole emergency repair scheme. By comparing group AHP weighting method with average weighting method, experiment results for the former showed a stronger correlation between quantified entropy values of complexity and the actual consumed time in repair, which indicates that this new method is more valid. 1. Introduction nuclear power plants. Besides three basic impact factors in software engineering, the abstract hierarchical architecture Electric power industry is vital to China’seconomy and power oftaskandtheconceptofengineeringjudgmentwerepro- grid plays a very important role in transferring electricity. posed. Finally the validity of impact factors is tested using The faults of overhead transmission lines are diverse, the assessment results. In the literature [5], a graph entropy locations of faults are stochastic, and circumstances of faults method was applied in emergency maintenance for marine are complex [1, 2] so that the emergency repair of overhead power facilities, which verified the correlation between MTC transmission lines is a sophisticated task. According to the (maintenance task complexity) and the consumed time in initial assessment, emergency personnel could figure out maintenance. In the literature [6], a graphical modeling an emergency repair scheme. However, the rationality and method for the operational processes was improved. By using feasibility of the scheme are all related to the complexity of Petri net, the model of operational processes was built, from task. Therefore, to precisely quantify and comprehensively which information structure chart and action structure chart analyze the complexity of emergency repair task has been a were extracted. However, selected operational objects were hot research topic [3]. only partial of the whole task so that the quantification in that So far, with regard to complexity quantification on emer- method was limited. gency repair scheme, most overseas and domestic scholars In software engineering, software complexity measure have been focusing on factors which influence the complexity includes two kinds of methods. The first is based on source andgraphicalmodelingmethods.Intheliterature[4], quanti- code quantification and the second is based on structure and fied impact factors on emergency accident were analyzed for chart.Intheliterature[7], entropy method was selected to 2 Discrete Dynamics in Nature and Society assess the complexity of marine power facility operation after similar characteristics were compared between soft- a ware complexity and emergency process complexity. Since the complexity of source code resembles the one of logic Condition Condition structure and program maintenance which requires amount i D b c A h of source code knowledge resembles emergency maintenance that requires amount of system information and background knowledge, entropy method can reflect not only the com- plexity of information but also the complexity of logic. In the d literature [8], graph entropy method was proposed as a way to quantify the complexity based on information structure chart and process control flowchart. Condition E Condition B To improve the accuracy of complexity quantification in e f the sophisticated power grid, in this paper, Petri net will be used to model an intact emergency repair task based on Condition F Condition C graph entropy method. To improve the design of weights in g computation of complexity, group AHP method is applied to set weights based on experts’ advice so that the design of Figure 1: Process control flowchart model . weights is more pertinent and its subjective errors could be also reduced greatly. 2. Complexity Quantification Method (1) The formula to calculate the graph entropy value is shown below: 2.1. Extraction of Impact Factors on the Complexity Quantifica- tion of Emergency Repair Task. Emergency repair tasks along transmission lines are always characterized by the urgency ℎ of the time, the randomness in the form of damage, the Entropy ===−∑() log2(), =1 flexibilityofthewayofrepair,andthediversityoftherecovery (1) phase. Therefore, in the emergency repair process, faults ( )= , should be eliminated as soon as possible by making the most of resources and techniques so as to diminish economic loss andreducethreatstosecurityofpowergrid.Featuresof facilities, the damaged condition, the composition of the where is a category defined according to the structure needed equipment and professionals, and the difficulties to chart; ℎ is the total number of categories; () is the assessed assemble or disassemble components should be all taken into probability of being in category ; is the number of nodes account. Besides, the allowed time of repair, the way of locat- in category ;and is the total number of nodes. ing the damage, the isolation level after the damage, and the (2) Application of graph entropy method will be illus- requirement on tools should be also considered. trated based on the process control flowchart model Tosum up, complexity quantification in emergency repair (Figure 1). of transmission lines is a comprehensive measure about Here, operation h and operation i are the same-type needed workload, resource, consumed time, and logic struc- operations, but their results are opposite. In this model, logic ture when damages to facilities are caused by accidents and complexity (LC) can be quantified by calculating the first- emergency repair is necessary. The impact factors on com- order entropy, and scale complexity (SC) can be quantified by plexity quantification could be sorted into 3 kinds: informa- calculating the second-order entropy. While calculating the tion complexity (IC), logic structure complexity (LC), and first-order entropy, those nodes with the same number of scale complexity (SC) of operation in emergency rescue and inputs and outputs in control flowchart are classified into the repair. same category. While calculating the second-order entropy, adjacent nodes with same number and same type within an arcdistanceincontrolflowchartareclassifiedintothesame 2.2. Graph Entropy Modeling. Graph entropy method is a way category. to quantify complexity based on information structure chart Based on the above rules of classification, nodes for model and process control flowchart. By establishing graph entropy are classified and listed in Table 1. model, the abstract process information can be displayed. By taking the calculation of the first-order entropy in There are two main ways of quantification: (1) chromatic model as an example, nodes for the first-order entropy information content, that is, the first-order entropy; (2) are classified into four categories as {a}, {b, c, e, f}, {d, g}, structural information content, that is, the second-order and {h, i}. represents entropy value of each impact factor. entropy. The probabilities for each category are 1/9, 4/9, 2/9, and 2/9, Discrete Dynamics in Nature and Society 3 4 Table 1: Classification and calculation for the first- and second- P2 T2 P order entropy of model . T1 The second-order The first-order entropy 3 entropy for T 5 for model P Category model P1 Neighbor Input Output Node Node node P3 102aab,c Figure 2: Graph modeling in Petri net. b, c, e, a, d, and h 212 b, c and f (or i) 3 2 2 d,g d b,c,e,andf chart is mainly used to determine the vital path that influ- d, g, and h ences the overall situation but could not reflect the amount 430h,ie,f (or i) of information needed in emergency maintenance task. 5ge,f,h,andiThe graphical modeling in UML is relatively simple, but it 6hc,f,andgoveremphasizes the logic of operation so that the needed information in emergency maintenance task is represented 7ib,e,andg insufficiently [10]. Petri net not only could draw the logic Entropy