| The modern energy system is moving towards a“Landscape-led,multisource coordination” direction.In North China,thermal power,wind power,solar power and other forms of power generation coexist,and wind power has been an important part of the power system can not be ignored.However,wind power is influenced by natural environment and other factors,directly integrating wind power into the grid will cause fluctuations in the grid.The grid side is affected and impacted by the wind power fluctuation.In order to reduce the impact,the curtailment rate can only be increased.Traditional grid systems have established physical and statistical prediction models based on wind power,but due to the influence of nonlinear disturbance error,the prediction ability of the model is limited to a certain extent,it is difficult to predict accurate wind power fluctuations over a period of time.The capacity of peak load regulation and valley filling of power grid system is affected,and the capacity of power grid access is also affected.FFT Fourier decomposition algorithm can be used to separate the functions of a particular frequency band,and this frequency decomposition idea can be applied to wind power decomposition to optimize the efficiency of the model.The wavelet function decomposition method is a variant of the STFT Fast Fourier decomposition,which can improve the resolution of the decomposition.In this paper,a wind energy storage system based on Daubechies Wavelet packet decomposition reconstruction algorithm is used to improve the accuracy and coverage scale of the wavelet function decomposition method for wind power generation.Wavelet algorithm itself has excellent decomposition and reconstruction ability,and can retain more frequency details,with a lower rejection of the wind power frequency reconstruction.However,the existing energy storage systems do not fully display their ability to accurately adjust the balance of power system because of the lack of a specific dispatching management method.In this paper,based on the improved wavelet packet algorithm,the original wind power is re-screened as a high,middle and low order function according to its characteristics,selecting and reconstructing the wind power frequency of three frequency bands as samples,combining with the decision-making results of energy storage dispatching system to carry out repeated feedback optimization,and selecting the reasonable reconstruction mode and reconstruction frequency,then the PSO particle swarm is trained repeatedly.Using MATLAB to build the improved multi-objective optimization Particle swarm optimization and find the optimal Pareto solution set.Based on multiobjective optimization,wavelet packet is introduced to reconstruct the signal.The Pareto solution set can be used to establish more than two optimization objectives,and the dual decision system of“Minimum curtailment and minimum operation cost” is introduced into the mixed energy storage model,it avoids the local optimization problem of PSO under single optimization objective,makes the decision-making model contain more dimensions,more diversity,and avoids falling into the problem of boundary crossing and disturbance of single dimension.The results show that the algorithm based on the improved Wavelet packet decomposition is more efficient and cost-effective in decomposition and reconstruction,and the decomposition frequency sub-band is more flexible.By reconstructing the target power signal and establishing the decision-making optimization model,the hybrid energy storage system can absorb the wind power of different frequencies according to the respective properties of the battery and the super capacitor,fully realize the accurate allocation of energy storage side resources,reduce the power system peak regulation frequency regulation pressure.The simulation results show that the control strategy adopted in this paper can ensure that the charged state of energy storage equipment can be maintained in a reasonable range through the constraint algorithm,by balancing the input and output power of the system and determining the charging and discharging state of the energy storage system,the hybrid energy storage system can significantly reduce the operation cost and improve the overall operation benefit of the power grid. |
