| Large-scale connection of new energy is always accompanied by a large number of power electronic equipment.With the rapid growth of wind power,photovoltaic power and other new energy grid-connected installed capacity,the traditional power system based on synchronous machines has begun to undergo structural changes,developing towards to a “double high”power system.With a high proportion of new energy sources and a high proportion of power electronic equipment,modern power system presents the characteristics of high fluctuations,high randomness and the fast-changing operating environments.At present,large-scale interconnected power grid generally adopts digital simulation to evaluate the operation performance of power grid and carry out system planning and design.Therefore,in order to accurately describe and analyze the structure and characteristics of the “double high” power system,it is necessary to establish an accurate mathematical model of new energy generation system.In recent years,the WAMS is widely used in power system,which makes it possible to obtain high precision real-time operation data of power grid,which makes it possible for the on-line dynamic modeling of power system components.In order to give full play to the role of WAMS data in the modeling of new energy power generation systems,this dissertation proposes an online parameters identification method for DFIG and photovoltaic power generation systems based on WAMS data.The main contributions of this dissertation are as follows.1.Aiming at the problem of new energy modeling and grid connected structure,the electromechanical transient model of doubly fed wind power system and photovoltaic power generation system are established.The models can represent the model of a single unit,or the equivalent model of wind farm or photovoltaic farm.Then,the structural characteristics of the closed-loop system formed by the grid connected equivalent model are analyzed,including the different effects of forward channel disturbance and feedback channel disturbance on the closed-loop identification.And the reason why biased estimation can be obtained by directly using the open-loop identification method to solve the closed-loop identification problem is discussed.Finally,a method to solve the closed-loop identification problem based on the prediction error method is proposed,and the estimation consistency of the prediction error method is analyzed.2.Aiming at the online parameter identification of DFIG,a parameter identification method based on WAMS data is proposed.Firstly,the identification conditions of DFIG parameters are analyzed.Then,a parameter identification method based on Kalman filter is proposed.Then,a single machine infinite bus simulation model of DFIG based on Matlab/Simulink is built,and the identification results of prediction error method and equation error method are compared.Finally,an example of parameter identification based on the measured data of wind farm WAMS in Guangdong Yangjiang power grid is given to prove the effectiveness and feasibility of the proposed method.3.Aiming at the problem of online parameter identification of photovoltaic power generation system,a parameter identification method of photovoltaic power generation system based on WAMS data is proposed.Firstly,the identification conditions of PV system parameters are analyzed,including the unique identifiability of parameters and the order selection of polynomial model based on L-curve.Then,a method of parameter identification of prediction error method based on Box-Jenkins model are proposed.Then,a simulation model of single machine infinite bus power grid with photovoltaic power generation system based on Matlab/Simulink is built,and the identification results of BJ model and ARX model are compared.Finally,an example of parameter identification based on WAMS data of photovoltaic power plant in Ningxia power grid is given to prove the effectiveness and feasibility of the proposed method. |
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