Modeling And Loss Analysis Of High Voltage Direct Current Light System

With the rapid development of electric power semiconductor technology and the application of Pulse width modulation technology, a novel High Voltage Direct Current(HVDC) based on Voltage Source Converter(VSC) has been realized. The VSC technology has many more superiorities, such as small cubage, strong function, decreasing filter device and simplifying conversation structure. For these reasons, this technology is named HVDC Light. HVDC Light technology relates to many academic fields such as electrical technology, modern power electronics technology, and automation control theory, etc. HVDC Light, which is expected to find increased use both at transmission and distribution level, has been attracted more and more attention for its favorable advantages, such as power supply to passive electrical network, quick and independent control of active and reactive power, the ability to make up easily multi-terminal network. However, because HVDC Light has emerged recently with a short period of development, especially for no practical HVDC Light project operating in our country, there are still many basic theories and application issues needing to be further studied.The main contents include:1. At first, this thesis introduces basic structure and components of HVDC Light system. Starting from the structure of single-phase circuit of VCS, the thesis briefly analyzes both the principle and control method of HVDC Light system.2. Steady state mathematical model and transient mathematical model are established. And then, the transient model in dqO frame is established through frame transformation and its decoupling controller is also designed. Simulation results realized by MATLAB show that the established model and designed controller obtain satisfying performance.3. A main part of this thesis is the AC-DC power flow calculation of HVDC Light system. Based on the deduced steady state mathematical model of HVDC Light suitable for Newton method power flow, this thesis proposes an alternative AC-DC power flow algorithm, which has the advantage of perspicuous structure, conveniently programming, and wide application. Then the validity and efficiency of this model and algorithm are verified by an example.4. The loss of HVDC Light is relative higher than traditional HVDC, which is one of the main barriers for the application of HVDC Light in bulk power transmission systems. In view of this characteristic, the thesis analyzes the loss components of HVDC Light, and then gives the loss calculation method of converter, and filter, etc.