An Uncertainty Power Flow Algorithm Based Centralized Pv Cluster

With the development of the centralized photovoltaic cluster,the problem of out-of-limit voltage in the cluster becomes more and more serious,which seriously affects its own stability.In the traditional power flow analysis of transmission network,the centralized photovoltaic cluster is regarded as a node,only considering the fluctuation of output,ignoring the internal operation of the cluster.The centralized photovoltaic cluster has a large cluster structure.Even if the port voltage is within the safe range,a large area of out-of-limit may occur in the cluster.In addition,due to the fluctuation and intermittency of output of photovoltaic power generation unit,the traditional deterministic power flow algorithm is no longer applicable.In view of above problem,this paper focuses on the study of uncertain power flow algorithm of the centralized photovoltaic cluster and analyzes the risk of out-of-limit voltage in the cluster.By using the algorithm proposed in this paper,a more constricted power flow calculation result can be obtained,which lays a foundation for solving the o ut-of-limit voltage problem of the centralized photovoltaic cluster,so as to ensure the stable operation of the centralized photovoltaic cluster,and then guarantee the safety of the grid connection.In order to solve the problem of uncertain power flow calculation in the centralized photovoltaic cluster,the Krawczyk-Moore operator is used to combine interval and affine arithmetic to solve the power flow equation,and on this basis,the out-of-limit voltage problem caused by power fluctuation in the centralized photovoltaic cluster is analyzed.The research contents of this paper mainly include:(1)Aimed at the shortcomings of current research about the internal of centralized photovoltaic cluster,this paper firstly describes the electrical structure of the centralized photovoltaic cluster,then the integrated line and the photovoltaic power generation unit is modeled.Finally,according to the established steady-state model,theoretically,there are risk of out-of-limit voltage both at the point of integration and inside the cluster.(2)Aimed at the failure of traditional deterministic power flow algorithm,based on the existing interval affine algorithm and considering that there are only load nodes and no generator nodes in the centralized photovoltaic cluster,this paper proposes a mixed power flow algorithm which can be calculated simultaneously in polar coordinates and rectangular coordinates.Through the simulation,it is proved that the algorithm in this paper can get a more constricted interval result,and does not consume too much computing resources,more in line with the needs of practical engineering.(3)This paper studied the voltage distribution under different operating conditions and the influence of power fluctuations on the voltage distribution of the centralized photovoltaic cluster,and analyzed the risk of out-of-limit voltage of each photovoltaic power generation unit in the cluster according to the power flow results.The mixed uncertain power flow algorithm proposed in this paper is used for simulation analysis,and the effectiveness and applicability of the improved algorithm are verified by the results obtained.By studying the voltage distribution under different operating conditions,the out-of-limit voltage problem caused by the fluctuation of photovoltaic power generation units in the centralized photovoltaic cluster is analyzed,and the correctness of the out-of-limit voltage mechanism analysis of the centralized photovoltaic cluster is verified.