Power Pulse Evaluation And Optimization Of Wind Turbine Based On Matching Characteristics

With the world's attention to renewable energy,the wind power industry has developed rapidly.However,the fluctuation of wind power output power causes potential safety hazards to the power grid and electrical appliances,at the same time it reduces the quality of output power,thus the development of the wind power industry is restricted.In this paper,the problem of dynamic output power ripple of independent permanent magnet wind turbines was addressed,and the exploratory research was carried out by combining experimental testing,theoretical analysis and optimization evaluation.Firstly,the matching experiments between different airfoil wind turbines and generators with different structures were carried out to disscuss the output parameters of each unit under different operating conditions,while the power pulsation evaluation indexes,power fluctuation amount?P and power fluctuation rate P_R,were put forward.Secondly,the influencing factors,causes and mechanisms of power pulsation were explored combined with the unit's own structure,operation status and dynamic harmonic response.Then,a two-level game optimization model was established to minimize power fluctuation,and the multi-objective optimization model of power fluctuation was constructed based on the comprehensive weighting method.Finally,the optimization effect of a power fluctuation optimization method for units in different operating conditions was evaluated,while a feasible guidance scheme for optimizing power pulsation was proposed.In order to solve the problem of power ripple optimization,the specific research contents were showed as follows:(1)Matching experiment test and analysis.Through the output information of matching experiment between wind turbine and generator,this paper intended to explore the trend of power fluctuation related evaluation indicators with the main influencing factors.The influence mechanism of each factor on power pulsation was clarified.Separation and acquisition experiments of electrical parameters for different airfoil wind turbines and generator orthogonal matching units with different structures were carried out and compared with the whole machine.In the time domain,the curves of each index and its influencing parameters were fitted.The aerodynamic output characteristics of different airfoil wind turbines were compared,and the best airfoil wind turbine and output characteristic generator were selected to form a matching unit.(2)Analysis of spectrum characteristics of electrical signals.Inductive control was added to the demagnetizing unit and the non-demagnetizing unit respectively by changing the operating state of the best matching unit respectively.By performing spectrum analysis on signals such as voltage,torque,and power,respectively,the signal pulsating component frequency band and the pulsating amplitude were identified in the frequency domain range.The purpose of this paper was to explore the mechanism of power pulsation by comparing the spectrum characteristics of output signals under four operating conditions and propose a power ripple suppression strategy.(3)The determination of power fluctuation minimization bilevel game optimization model.The minimization of power fluctuation was regarded as a game problem and a natural-artificial non-cooperative game model was established by taking the nature of changing the incoming wind speed and the artificial side of changing the tip speed ratio as the game participants.Under the constraints,the decision variables were changed to reach Nash equilibrium and the optimal solution of each index was obtained.A cooperative game model with minimization of power fluctuation as optimization objective was established,and the Pareto optimal solution satisfying the minimization of power fluctuation was obtained by taking the power fluctuation amount?P and power fluctuation rate P_R as decision variables.(4)A power ripple optimization and evaluation model was proposed based on weight analysis.Considering the coupling relationship and the degree of influence difference of many evaluation indicators,the combined weight analysis method based on entropy method and analytic hierarchy process was used to solve the influence weight of each evaluation index on the overall power pulsation of the system.Based on the comprehensive weighting method,a multi-objective optimization model was established to comprehensively evaluate the output power characteristics of generating units.The main optimization objective was power fluctuation evaluation index,which took into account voltage harmonic distortion rate,wind energy utilization coefficient and other voltage indices and aerodynamic indices as power fluctuation related evaluation index.The target values of four typical operating states were analyzed and a power ripple minimization optimization scheme was proposed in this paper.