Research On Dynamic Equivalent Model For Wind-photovoltaic-storage Hybrid Power System

With the increasing capacity of grid connected wind-photovoltaic-storage hybrid power, the impact on the stable operation of power system, which be caused by intermittency and randomness of wind power and solar power, is becoming more and more obvious. Therefore, dynamic equivalent modeling for hybrid power system have become important as a tool to analyze the active power output characteristics, provide guidance for active power control algorithm and evaluate the influence of power grid stability with large-scale grid-connected wind-photovoltaic-storage hybrid power system.Considering the structure and operational performance, this paper proposes a dynamic equivalent modeling method for wind-photovoltaic-storage hybrid power system based on fuzzy clustering algorithm. The details are as follows:1. According to the structure and dynamic operational performance of hybrid power system and the subsystems, an overall equivalent modeling method for hybrid power system is studied. Firstly, unit-level models are established on the basis of the composition and operational principle of power unit. Secondly, three plant-level equivalent models are built separately in accordance with the three parts of hybrid power system – wind farm, photovoltaic power system and battery energy storage system. Finally, the dynamic equivalent model of wind-photovoltaic- storage hybrid power system is set up by combining plant-level models together.2. In plant-level equivalent modeling, in view of large differences of operational performance between wind generators and photovoltaic power generation units, this paper proposes a multi-machine representation equivalent modeling method based on fuzzy clustering algorithm used for analyzing the active power output characteristics of wind farm and photovoltaic power system. Firstly, indicators which can characterize the active power output performance of doubly-fed induction wind generator(DFIG) and photovoltaic power generation unit are researched. Secondly, fuzzy C-means clustering algorithm(FCM) is first applied to the modeling of wind farm and photovoltaic power system. Clustering results are obtained after analysing the indicator data by using FCM. Finally, the parameters calculating methods of equivalent models are provided. Owing to consistent operational state of energy storage units, single-machine representation method is chosen for the equivalent modeling of battery energy storage system.3. Using Matlab/Simulink platform, plant-level dynamic equivalent models of wind farm, photovoltaic power system and battery energy storage system are established. Then, dynamic equivalent model of wind-photovoltaic-storage hybrid power system is built by putting plant-level equivalent models together. Simulation results show that the established dynamic equivalent model can reflect the active power dynamic characteristics of hybrid power system effectively. The model is simplified and the computation complexity is reduced. The dynamic equivalent model is suitable for analyzing the active power of wind-photovoltaic-storage hybrid power system.