Study On Transient Stability Of Wind-thermal-bundled Power Transmitted With AC/DC System

Wind power in Gansu province is mainly concentr ated in the Hexi corridor area.The grid is not strong enough and far away from the load center,which is a typical weak grid.With the successful operation of the Jiuhu HVDC transmission system,the large scale wind power in Hexi area passes through the near HVDC converter station to realize the wind power supply,the high proportion of wind power and the large capacity HVDC transmission will bring great risks and challenges to the safe operation of the Hexi power grid.In order to ensure security and stability of wind-thermal-bundled power system,it is necessary to carry out further study on transient stability and interaction among wind turbines,thermal generators and HVDCs in Hexi weak grid.Based on Gansu Hexi wind-thermal-bundled power energy base transmitted with AC/DC system,the transient stability problems which is easily caused by the characteristics of "large HVDC capacity,weak AC grid structure and high proportion of wind power" in the Gansu Hexi power grid,is aimed at improving the overall transient stability of the Hexi grid.A series of research is carried out on the interaction between the relationship of three characteristics.The reasons for the instability of the hybrid system are analyzed when the main AC channel faults in the wind-thermal-bundled power system.The influence of different DC capacity,location of faults and the proportion of the wind on the transient stability of the hybrid system is discussed.The impact of two typical faults of the DC system on the Hexi power grid the impact on the safe operation of the bundled wind power are analyzed.The measures to improve the Hexi hybrid power grid are proposed,the new large synchronous condenser is connected to the Jiuquan converter station,and the optimization measures can improve the transient sta bility of the hybrid system.First,on the premise of good low voltage crossi ng ability of the wind turbine,the transient stability differences of the Hexi power grid is simulated and analyzed under the different fault capacity,different DC locations and the different ratio of wind-fire bundles,and transient stability of wind power access is analyzed by the classical equal-area criterion.Secondly,based on the DC system block fault scene of the Jiuhu HVDC transmission channel,the transient stability of the Hexi hybrid power grid under the DC system block fault with different DC capacity and different by different proportions of wind power is analyzed,and the transient characteristics of the Hexi power grid are analyzed based on the Jiuhu HVDC commutation failure,the transient characteristics of Hexi power grid during the fault s are analyzed,and the cause of wind turbine failure is analyzed.Finally,based on the fault scene of wind-thermal-bundled power system,the good dynamic reactive power regulation capability of the large synchronous condenser is analyzed,transient instability risks of Hexi power grid under AC and DC faults are reduced and the simulation verification is carried out in the Hexi power grid.