Equivalence Of Photovoltaic Cluster And Identification For Inverter Controller Parameters

In china,grid-connected photovoltaic(PV)power generation is an important way to make use of solar energy.With the large-scale development of PV generation,regional centralized PV cluster and regional decentralized PV cluster have been formed,in order to meet the needs of PV scale utilization,it is necessary to establish the equivalent model of the two types of PV clusters in a simplified way,thus their output characteristics can be conveniently studied.PV inverter is the core component of PV system,which plays a decisive role in the transient characteristics of grid-connected PV system,therefore,quickly and accurately obtaining the parameters of inverter controller has great significance in analysis of transient characteristics of PV generation system.First,the principle of two-stage PV power generation unit is described and its mathematical model is presented,and based on that,the model of regional centralized PV cluster is studied.The principle of equivalent modeling is given,according to the principle,the equivalence of PV array,collection line,transformer and inverter are studied,thus a single-machine equivalent model of regional centralized PV cluster is established,and simulation test has validated this method.Then,a multi-machine equivalent modeling method for regional decentralized PV cluster is presented.The clustering index is selected from the transient response curves of PV system,the PV systems with close dynamic characteristics are divided into the same group by clustering algorithm,and the PV systems in the same group are combined into an equivalent PV system,thus a multi-machine equivalent model of regional decentralized PV cluster is established.Simulation analysis is performed using an actual distribution network in Anhui province.Finally,the parameters of grid-connected PV:inverter controller are identified.The sensitivity analysis of the parameters is carried out,accordingly,a two-step identification strategy is proposed,the first step use a grid fault to identify all voltage loop parameters and the proportional coefficient of current loop,and the second step consider a DC voltage reference jump disturbance to identify the integral coefficient of current loop and the inductance value.The adaptive differential evolution is taken as the identification algorithm,which adopts adaptive strategies for algorithm parameters in order to speed up the convergence and enhances the balance between the global search and local mining.The identification model is verified by real-time simulation platform.