Modeling And Simulation Of HVDC System

With the development of power electronic componets, direct current transmission technology is widely used in electric power transmission system. Half controlled thyristor is limited in the use of traditional high voltage direct transmission system because of the limitation of power electronic technology. Direct current transmission technology whose major technique is voltage source converter technology does not play a main role in electronic power transmission system until the invention of all control type of insulated gate bipolar transistor. Pulse width modulation technology is used in this new transmission technology, besides, all control of bipolar transistors works as voltage source converters. This direct current transmission system is also called flexible direct current transmission system or light direct current transmission because of the simple structure and small occupation of land. This transmission technology is much better than traditional high voltage direct current transmission system, which can play an important role in distributed power supply, passive load power supply, city power supply and so on.The selection of ac and dc power transmission has always been the focus of the debate. HVDC and ac power each have advantage, for a long time, ac power play aleading role, But a with the advance of power electronics technology and emergence of new mode of power supply, dc power transmission mode again brought to the attention of the people. Especially long-distance transmission system, the dc transmission system has much advantage.The mode of Light dc transmission is a new kind of transmission mode that uses the voltage source inverter. As retain the advantages of traditional dc transmission problem and overcome a lot of the power system transmission problem, the Light dc transmission system get the favour of many scholars. Mang scientific research institutions have done research so many in this area.This dissertation talks about the structure of light direct current transmission system, the operation mode, the technical superiority and the field of application. A mathematical modeling is taken to make power flow calculation, to make system simulation. Choosing appropriate control methods, taking a verity of action protecting in method, simulating according to all kinds of working situation by SIMULINK. The reliability and stability of this light current transmission can be tested through common obstacle’s trial. At the same time, the development of light direct current transmission system in the future is included in this dissertation.