| Main electric connection is the main body of the substation's electric parts, and is one of the entrances through which the electric energy is passed. It plays an important role on an electric power system itself and the reliability of power supply, flexibility of operation, ease of maintenance and rationality of cost of the substation, and also has effect on the choice of the electrical devices, arrangement of switchgear, relay protection and method of controlling. So it's necessary to deal with all of the relative parts properly, establish a scientific assessment system for main electric connection, analyze the effects of relative factors roundly, assess all kinds of the economical and the technology projections and confirm a reasonable main electric connection.According to "design criterions for 35KV-110KV substation", high-voltage main electric connection of 110KV terminal substation tends to adopt line-transformer group connection, and for 110KV midway substation, the single bus-bar, subsection single bus-bar or extended bridge connection is best the choice, but main electric connections including SF6 breaker should not set standby bus-bar.All of the above connections have been adopted in engineering. But there still have been some problems, such as fallibility, diseconomy of operation etc. There isn't a affirmative conclusion to which connection suits midway substation and which one suits terminal substation.This paper presents a synthetic assessment system for main electric connection, especially for high-voltage main electric connection of 110KV substation.In this paper, assessment system data are established firstly. From allthe relative factors that will have influence on main electric connection design, the dominating ones are chosen to analyze and suppose. And then these factors are classified into three kinds: the first is the exactly quantitive data which can be directly enumerated, the second is exactly quantitive data which are indirectly enumerated, and the last is the fuzzily non-quantitive data. The first two kinds of data are acquired by drawing main electric connection diagrams, designing main plane arrangement diagrams, collecting device material data and calculating budgetary estimate of civil engineering. But for the last, we get them by Delphi Method.On the base of assessment system data, we can calculate and analyze the reliability of all the main electric connection schemes by minimal path set method. Above all, we will have some hypotheses, and then establish the elements' three-state models which including normal state, fault state, and overhaul state taking into account the calculating accuracy and the limit to the data. But most of the electric elements are mendable, and once the element has fault it must stop operating, after being repaired it must be put into operation immediately, so in calculating, we can suppose the element has two states: normal state and fault state. After establishing calculating pane diagrams we can get the reliability results of all the main electric connections by minimal path set method.By comparing the three assessment methods, namely, Analytic Hierarchy Process (AHP), Principal Component Analysis, and Fuzzy Evaluation Method, the first one is adopted. Fuzzy Evaluation Method is a synthetical evaluation process which involves the ideas of system engineering and fuzzy set theory, by taking all factors into account, establishing an assessment criterion system, getting some patterns or standard stylebooks, identifying and calculating the relative membershipgrade of each research object belonging to all the patterns, calculating relative state eigenvalue, judging the research object belonging to which pattern or standard stylebooks.Based on the above research, according to the demands of synthetical assessment method, we ascertain the evaluation objection set, namely assessment criterion. In the high-voltage main electric connection sythetical assessment system for 110KV substation, there are 6 kinds of factors concerned. Orderly they ar... |
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