Simulation And Coordination Control On Large Scale Wind And Thermal Power Transmission By HVDC

Wind energy resources are distributed concentratedly in China. Most of them are in the west, north and coastal regions. Hami of xinjiang, Jiuquan of Gansu province, the western and eastern Mongol etc.are regions with the most wind energy resources. It is very suitable to develop centralizing large scale renewable energy base. Large-scale wind power integration needs power system with strong peaking balance ability for the fluctuent and randomness of winder power. While the scale for power system in the west and north regions are small. The proportion of thermal electricity is high, which causes the peak load regulation capacity is weak. To achieve large scale of wind power development and effective utilization, it is required to intensify the study on wind power digestion and comprehensively consider wind power bases and transmission channel construction. The trans-regional ultra high voltage transmission projects are needed to be constructed simultaneously to transmit wind power from the north and west regions to the load centers such as the north China, central China, east China etc. for digestion. Developing larg scale wind power and transmiting it to big network is the inevitable requirement of China.The features of the Ultra High Voltage Direct Current (UHVDC) are high transmission capacity, long distance etc. Up to date,3UHVDC projects have put into operation in China. Several UHVDC projects are in planning and construction. UHVDC will become an important method to deliver lare scale wind power in the future, which is an effective means to minigate the inadequate energy power and a essential condition to promote the construction of large scale wind power base. The flexible control function on active power and reactive power of the HVDC link could be used to adapt the fluctuation and fault characteristics of wind power to improve the safety and stability of the large scale wind power integration.The following items are the major research of this doctoral dissertation.(1) A digital-analog hybrid model of synchronous generator with direct drive wind turbine is formed based on real-time digital simulator HYPERSIM and Voltage Source Converter analog model. The dynamic behavior and responding character of the model is be studied by simulating steady and transient tests including network faults.(2) A digital-analog hybrid model of large scale wind and thermal electric power transmission by HVDC link is formed based on real-time digital simulator HYPERSIM and UHVDC analog model. The power connection technology is used to connect analog UHVDC simulator with HYPERSIM and simulate the power exchange between two systems The dynamic responding character of the model is verified by steady and transient faults simulating.(3) The interaction and cooperative control stradegy of large scale wind and thermal electric power transmission by HVDC link is studied with real time digital analog hybrid simulation system. The control strategy is validated by real time digital analog hybrid simulation test.The following items are the major innovation point of this doctoral dissertation:(1) A digital-analog hybrid model of synchronous generator with direct drive wind turbine is formed, which is able to connect with the real converter controller to research the dynamic characteristic of wind turbine integration. The real dynamic characteristic of the wind turbing controller could be responded.(2) A digital-analog hybrid model of large scale wind and thermal electric power transmission by HVDC link is formed, which could meet the research requirements from not only scale but also precision.(3) The interaction lever between ac and dc system of large scale wind and thermal electric power transmission by HVDC link is evaluated. A ac-dc coordinative control strategy is put forward to improve the fault recover features of large scale wind and thermal electric power transmission by HVDC link.This doctoral dissertation emphasizes integrate theory with practice. The main object is to solve the practical problem met in the development of China power network and put forward the feasible solutions?The technical problems of real-time simulating the dynamic character of IGBT in wind turbine exactly are solved. This model provides an indispensable technical measure to study the strategy and parameters of the real wind turbine controllers; The technology difficulty is solved to exactly simulating HVDC system dynamic responding character at the same time simulating large scale wind and thermal electric power system. This model provides an indispensable technical measure to study large scale wind and thermal electric power transmission by HVDC link and the coordination control between ac and dc system; The effective and feasible cooperative control strategy is put forward to promote power system failure recovery and improve system stability. The study results provide an indispensable technical support to the application of large scale wind power transmission by UHVDC link.