Simulation Analysis Of Back-to-back Converter Station

Along with the development of power electronic device (such as mercury arc valve, thyristor, GTR, GTO, IGBT and so on) since last century 50', HVDC(high voltage direct current) has demonstrated unique superiority in the long-distance large-capacity power transmission, submarine cable power transmission and the asynchronous networking of AC system, HVDC and its correlation technology obtained more and more widespread value.In our country, energy distribution is not uniformity and the load development is unbalanced, long-distance large-capacity power transmission becomes imperative. On the other hand, interconnection between electrical networks is also inevitable in the electric power industry development. Interconnection among big area networks and independent province networks is entering the implementation stage. Lingbao BTB HVDC engineering is the first BTB HVDC networking (Central China electrical network and Northwest electrical network) project in our country. It is also a demonstration project independently designed and manufactured in our country. It accumulated the experience of HVDC project designing, manufacturing and operation for our country.In order to obtain satisfaction performance, it is necessary to estimate the performance, questions and measures of the HVDC system. Because the HVDC system has certain particularity in the operation mode and recovery processing, requirement for the polar control system is much high. Therefore, it comes to significative to research the transient and steady state performance of the HVDC system by using the simulation tool.In this thesis, the simulation model of Lingbao BTB Converter Station is built using simulation software PSCAD/EMTDC(power system computer aided design/electro-magnetic transient in dc system) according to the Lingbao BTB HVDC project. The transient state and steady state of this system are analyzed. This thesis mainly including below content:(1) The HVDC system type and BTB HVDC characteristic are discussed. The constitution of the HVDC system and the principle of converter and the basic control mode of HVDC are introduced. (2) According to the Lingbao BTB Converter Station, the simulation model of transmission system and polar control system are built using the simulation software PSCAD/EMTDC. Based on this model the general faults of HVDC system , including three-phase fault and single-phase fault of AC system, are simulated. The dynamic behavior and recovery processing in fault are analyzed.(3) The mechanism and the detect method of HVDC commutation failure are discussed. The measures for avoiding commutation failure are introduced. Take Lingbao BTB Converter Station as the example, the factors causing commutation failure and relations between each factor are analyzed. The process of commutation failure is emulated. The simulation results are contrasted with the field record. Two groups wave are similar.