Research On The Method Of Data Integration Based On Ontology In The Power System

With the development of the network and requirement of power system management, a large number of heterogeneous data sources have been built at the historic moment. But what is needed in the process of constructing the power system is to integrate the distributed, heterogeneous data. The traditional data integration methods are lack of formal semantics of the description. The thesis focuses on how to establish a semantics-preserving data integration system.Firstly this thesis discusses the current research situation about our country and abroad, several traditional integration technologies are introduced in this part, at the same time, we also compare the disadvantages and advantages among them. Then the data integration concept is illustrated, based on this, the concept and theory of ontology are raised.Using ontology technology, this thesis designs a data integration model in power system. This model is mainly divided into three layers:the application layer, query processing layer, data source layer. The application layer mainly completes the task of display the querying result, query processing layer is responsible to transfer the query which is from the application layer into each independent query of every data sources, processes the result of each independent query, data sources layer contains various data sources which are needed to integrate.In this thesis, we use Protege to build the data model. In order to integrate the data sources better, we build the global ontology. According to local ontology, we first extract the data schema, discuss the methods of learning OWL ontology from the database, give the algorithm about the translation from ER schema to OWL ontology, and discuss how to realize the mapping between the global ontology and the local ontology. The analysis shows that the plan can solve most problems of the semantic heterogeneity, and can construct ontology automatically. For query processing, we use language OQL to build the query of the global ontology and transfer it into each of the data source query.At last this thesis realizes the integration system and tests it, which verifies the data integrated model based on Ontology in the Power System is feasibility.