¡À 800kv Yun Guang Hvdc Transmission System Reliability Studies

Direct Current Transmission is the most suitable project when the distance is long or bulk capacity is transmitted.With the implementation of the stratagem of the electric power West to East Transmission in our courtry,this program is widely adpoted.A passel of HVDC transmission systems covering long distance,carrying bulk capacity and higher voltage projects were set up and put into service.YunNan-GuangDong Ultra High DC is first±800kV direct current transmission project in the world.As an unprecedented project, it is insistent and necessary to evaluate its reliability.Based on YunNan-GuangDong Ultra High±800kV DC,its reliability is implemented and researched.For the sake of reasonable reliability model,the trait of UHVDC transmission was analysed before evaluation.At the same time,the reasonable original parameter and reliability index system are made.Compare with EHVDC transmission system,UHVDC transmission system features largely in its complex structure and various states.The precondition and dificulty of the system reliability evaluation is that how to establish the mathematical formulas under the practical operation condition,which should not only satisfy the request of engineering practice,but also be simple and feasible.Based on the theory of Markov Processes and the properties of transitional frequencies among cumulative states.Then through analysis of the operation conditions of system,the space situation and the logical relations of the elements,the whole converter system are divided to several subsystems,and their equivalent models are made by reducing the state space diagrams of subsystems,The state space diagrams of whole converter system are made by combining the equivalent models of the subsystems after fully studied their inner characteristics and wholly considering their relations.Not only every exact state or accumulating state but also the influence of the random shifting frequency between the states are considered when analysis of the operation states of the system by Frequency and Duration(FD)Method.At last the reliability evaluation of whole converter system are calculated and analyzed.Based on the result,different element parameter or different space situation has different influence the result of reliability evaluation,the weakness calculation is made.After analyzing the reliability results,a series of enhancing means are gived.The DC reliability management information system based on component software design is developed.The functions are implanted by component,which much enhances the quality of software,shortens exploit time.The data is analyzed using expert system component,which realizes the aptitude of DC reliability analyzing.This thesis introduces the DC system states and indices,the database components of the system,the system structure and component functions.