Modelling renewable energy sources into a grid simulation

Abstract

Nowadays, a reliable supply of electrical energy is essential for a modern, flourishing society and industry. Individual customers are supplied with electricity through a nationwide network consisting of several voltage levels. In view of climate change and the need to reduce CO emissions, the importance of renewable energies such as wind and solar energy is constantly increasing. These offer considerable advantages in terms of environmental friendliness and resource conservation, but also bring new challenges for the energy supply. In particular, the volatile and weather-dependent generation of these energy sources places high demands on the stability and reliability of the network. For this reason, the issue of energy storage is also becoming increasingly important in order to balance out the fluctuating generation of renewable energy sources. As the current demand must be balanced at all times by the power plants feeding into the grid, a sudden change in demand or feed-in can lead to grid instability. In addition to voltage stability, ensuring a constant frequency, which in Austria is 50 Hz, is one of the most important tasks of the grid operators. While small deviations can be tolerated by the system, excessive deviations can lead to grid failure. For these reasons, it is therefore in the interest of the individual market participants and in particular the grid operators to have reliable grid models. The type of grid model to be used depends on the phenomena to be investigated. For example, if the behaviour of the grid is to be investigated in the event of faults, e.g., short circuits, dynamic models must be used. For fault-free operation, it is sufficient to use stationary models. These are characterized by their lower complexity compared to dynamic models. Stationary grid models form a solid basis and can be expanded into a dynamic simulation if necessary. The aim of this work is to model wind power plants, photovoltaic systems and battery storage systems that are integrated into a stationary grid model. The models in turn consist of several submodels, which represent the most important components of the individual power plants. For example, the wind turbine (Type D) consists of a rotor, generator, generator- side converter and grid-side converter. All models are limited to the stationary state, which means that disturbances during operation cannot be represented. Parameters from the literature, data sheets and weather data, e.g., irradiation data and wind speeds, which can be obtained from various databases, serve as input for the models. The models are then validated and suggestions for extensions are made.The work is divided into the following sections: 1) Theoretical foundations of the renewable generators wind power, photovoltaic and battery storage, 2) Presentation of the individual models and their sub-models, 3) Validation of the models and 4) Conclusion and outlook for extensions.