Research On Key Technology Of Multi-objective Optimization Control Of Wind Energy Conversion System

Accompanied by the urgent need of human to protect the ecological environment,clean energy,especially wind power get long-term development.Wind energy conversion system(WECS)has kept a continued rapid growth during the past decades,at the same time,wind turbines are facing chanllenges to reduce the levelized cost of energy,improve the reliability and fit the grid friendly request.Under this background,to promote wind power technology is very important.Centre on the optimization control of wind energy conversion system(WECS),this paper foucs on WECS modeling,power production improvement,power smoothing and load optimization control,and finally formed a multi-objective optimization control technology.In terms of WECS modeling,several WECS models with different details are built according to the research demand.The requirements of refined modeling are illustrated.A simplified model suitable for power tracking control study is established.The simplified methods for modeling the key dynamic behavior of WECS,including flexible mechanical structures,dynamic aerodynamic behavior and the influence of wind speed spatial distribution,are presented for the conventional power system simulation tools.Then the linear model of the whole turbines has been established,which can be used for designing main controller.Finally,a hardware-in-loop real-time co-simulation platform fits the refined modeling requirements is designed.The interface device of the co-simulation is developed,the stability of interfacing is analyzed and the error is evaluated.In terms of optimal power generation control,the study on optimal power production control under overall wind speed/ overall frequency band is presented.The limiting factors of the speed operation range are analyzed;the existing maximum power tracking methods are reviewed.The control strategies are proposed from both static tracking and dynamic tracking aspects to better maintain optimal tip speed ratio operation.In constant speed operation mode,an optimal pitch control is presented based on bladed-element momentum theory analysis.Finally the torque-pitch coordinated control below the rated wind speed is proposed,which is aided by the blade-installation-error elimination technique and the dynamic compensation embedded effective wind speed estimation method.Those improved control methods jointly formed the whole wind speed/ wind spectrum optimal power production control.In terms of power smoothing control,defined the key frequency band for participating in power smoothing.Then the frequency domain characteristics of electric power fluctuation have been analyzed under different operation modes,which revealed the impacts of turbine parameters,control manners and control parameters on electric power fluctuation.On this basis,the power smoothing schemes utilizing rotor inertia have been worked out,which will not lose power production and will not threaten the safe operation of WECS.In terms of optimal load control,the integrated load mitigation control on drive train and tower has been researched.A quantitative configuration method of drive train electrical damping is proposed.The key parameters influencing torsional vibration under power grid failure condition are analyzed,and an optimization control is proposed from the point of lowering the stimulation soure of torsional vibration,thus forming a comprehensive scheme to supprese the torsional vibration under grid fault.Finally,the active damping control strategies for both tower oscillation modes have been studied.In terms of multi-objective optimization control,the mutual influences between power fluctuations,maximum power point tracking ability and drive train damping have been analyzed in overall wind speed region.The frequency-distinct control and the optimized drive train damping configuration scheme have been studied to realize multi-objective optimization.The integrated optimization control technique can meet the requirement of multiple optimization objectives.The proposed control strategy have been fully simulation,the simulation results accord with the results of theoretical analysis degree is high,the simulation results show that the presented optimization control strategy to produce the desired effect,implementation capacity,smooth and reduce the load of power integrated optimization.