Research On Evaluation Method Of Grid-Connected Photovoltaic Power Station's Location And Capacity And Access Mode

With the increasing demand of the global energy crisis on the development of new energy,the access of photo-voltaic power stations has become a necessary trend of research.How to overcome the impact of grid connected photo-voltaic(PV)has also become a problem to be solved.In this paper,a practical engineering model of photo-voltaic cells is established and its implementation in simulation software is completed.A maximum power point tracking algorithm based on reference current is proposed in view of the advantages and disadvantages of existing approaches for maximum power point tracking of photo-voltaic power sources,a maximum power point tracking algorithm based on reference current is proposed.By setting the reference current,an accurate discrimination of the influence factors of light intensity mutation is realized,and the calculation speed is guaranteed under the condition of improving the accuracy of the algorithm.In view of the large scale of modeling and simulation of large-scale photo-voltaic power plant,a method of large-scale photo-voltaic power station equivalent modeling is given.This method can greatly reduce the scale of the photo-voltaic power station model and significantly reduce the calculation amount on the premise of ensuring the accuracy of the simulation results.For photo-voltaic grid connected location and capacity problem,this paper gives out a method of locating and sizing photo-voltaic power generation considering harmonic index.In this method,the grid inverter is regarded as a harmonic current source with infinite internal resistance and superimposed by multiple frequency harmonics.On this basis,the fundamental wave flow and the wave flow of the system are calculated.Taking comprehensive optimum of voltage index,power losses and harmonic index as objective of the algorithm,considering the upper limit of the voltage harmonic content of the node as the constraint,while improving the system voltage distribution and reducing the net loss,it avoids the problem of high harmonic content in all parts of the system because of the photo-voltaic access.The multi-objective optimization algorithm based on improved genetic algorithm is used to solve the model operation.The results on the IEEE-33 node system prove the validity of the proposed model and method.Based on the study of different photo-voltaic access modes,a set of complete photo-voltaic access index system is established on the basis of the research of different photo-voltaic access modes.This index system takes into account the actual technical requirements of photo-voltaic grid connection,and realizes comprehensive evaluation of the data of indicators of upper level indexes(voltage,frequency,harmonic,net loss)of a certain power grid;in terms of index weighting,the two level weighting method is adopted to combine Delphi method and entropy weight method to empower all indexes in the index system established.In the evaluation of access mode,the characteristics of the technique for order preference by similarity to ideal solution and the gray correlation method are analyzed.Following that,the evaluation method combining these two methods is proposed.This method considers the influence of PV grid connected to the different level of the grid and determines the optimal way for photo-voltaic power stations to enter the grid.Finally,using the evaluation method of the photo-voltaic power station access scheme,this paper evaluates the different schemes of the access of the photo-voltaic power station to the grid in a certain area and sorts the evaluation results,and finally gives the best way of grid connection of the photo-voltaic power station in this area.