Research On Coordinated Control System Of Wind Power Smoothing And Variable Speed Hydropower Unit

With the increase in the proportion of wind power installed capacity in the power system,the fluctuation of the wind power in the grid is more obvious.Fluctuant wind power is merged into the grid to cause the power quality of grid to decrease and improve the requirements of scheduling plans.The smooth integration of wind turbine power into the grid is conducive to reducing the operating costs of power system frequency regulation,voltage regulation and dispatching.The dissertation is incorporated into the power grid from the perspective of the rotor kinetic energy control of the wind turbine and coordinated control of variable speed hydropower unit.Firstly,the mathematical model of permanent magnet direct drive wind turbine and doubly fed variable speed hydropower unit are established.Using modular modeling,the mathematical model of permanent magnet direct drive wind turbine with wind speed,wind turbine,pitch system,permanent magnet synchronous generator and converter,and power smooth indicator are established.The mathematical model of doubly fed variable speed hydropower unit including hydraulic turbine and water diversion system,speed optimization,speed governor,doubly fed induction generator and converter is established,and the fast power response of doubly fed variable speed hydropower unit is simulated.Secondly,the speed fluctuation area of the rotor kinetic energy control of the wind turbine is studied.The basic principle of rotor kinetic energy control is analyzed,and the wind turbine runs at a non-optimal speed with the rotor kinetic energy control,and the speed decreases due to the rotor releasing kinetic energy,and it is easy to enter the large fluctuation area of the wind turbine’s speed.In order to avoid the wind turbine entering the area of large speed fluctuation,the optimal speed is used as the minimum value of the given value of the rotor kinetic energy control speed.Through simulation analysis and comparison of wind turbine power smooth index,the effectiveness of the proposed method in achieving power smoothing and avoiding entering the area with large speed fluctuation is verified.Then,the smooth change law of wind turbine power in different operating areas is studied.The typical operating curves of different operating areas are set according to different blade tip speed ratios,and through simulation analysis and comparison of wind turbine power smoothing indicators,the power smooth effect of the deceleration curve deteriorates with the increase of cycle due to the change law of wind turbine power with speed is the contradiction with rotor kinetic energy control power with speed.The given speed of the optimal curve rotor kinetic energy control exceeds the optimal speed,and the law of wind turbine power change with speed is the same as the law of rotor kinetic energy control power change with speed,and the power smooth effect becomes better with the increase of cycle;The change law of the power of the acceleration curve wind turbine with the speed is more obvious than the power of the optimal curve with the change of the speed,and the power smooth effect is better with the increase of the cycle.Finally,the smooth and coordinated control of power of wind power and variable speed hydropower units is studied.The power smooth effect of the wind-hydropower coordinated operation system with variable speed hydropower unit is better than that of the wind-hydropower coordinated operation system with fixed speed hydropower unit during the step wind speed and random wind speed.The power smooth effect of the wind-hydropower coordinated operation system decreases with the increase of random wind amplitude.In the random wind of the largest amplitude,the power of wind power smoothing control and wind power maximum power tracking control are introduced into the wind-hydropower coordinated operation system with variable speed hydropower unit,and through simulation analysis and comparison of the power smooth index of the wind-hydropower coordinated operation system,The power smooth effect of the wind-hydropower coordinated operation system controlled by wind power smoothing is better than the power smooth effect of the wind-hydropower coordinated operation system controlled by the maximum power tracking control of wind power.The results show that the smooth control of wind power and the coordinated control of variable speed hydropower unit achieve the smooth integration of power into the power grid,which is conducive to building a new power system and promoting low-carbon energy transformation.