Resources adequacy – Analysis of renewable generation variability
Czech Technical University, Faculty of Electrical Engineerin
The enormous increase in the integration of renewables (RES) into the energy system with the system of subsidies (in particular the guaranteed purchase price, ie. Feed-in tariff) had serious consequences in the energy markets and the operation of the electrical system. The current way of supporting renewable energy sources and market mechanisms caused a surge supported sources, a significant change in the mix (conventional plants and operationally expensive resource are pushed out – called merit order effect) and last but not least, a significant increase in electricity prices for end users. Intermittent and highly volatile nature of the sources based on renewable energy sources additionally causes more and more problems with the management of the electricity system.
One of very important terms related to RES integration is Resources (generation) adequacy. Generation adequacy is the ability of the sources in the power system to match the load on the power system at all times. Developing this definition more broadly and focusing on generation side, we can consider this issue as a looking for the optimal structure of sources for electricity generation considering all economic, environmental and technical aspects of all types of sources. Importance of generation adequacy analysis increases with wide RES development. Unpredictable variability of renewable production dependent on natural conditions requires adequate sources to cover so called residual load. This electricity generation should be reliable and as much as possible cost effective.
This paper presents short-term variability analysis of RES production dataset from different sources in the Czech Republic. Hourly gradients are analyzed to be used for extensive analysis of short-term variability and probability of hourly changes of renewable production. We used standard stochastic approach of data analysis and we set characteristics of hourly variability of renewable production (capacity factor, capacity credit). These results are very important for dimensioning of backup sources and also for optimization of energy sources portfolio. Finally, the results were compared to results of analysis of stochastic short-term variability of renewable production in Germany.
The main aim of this paper is a comparison of characteristics of variability of renewable production between sources in the Czech Republic and Germany. Germany as a European leader on renewable field outlines the issue how to deal with resources adequacy. Germany and the Czech Republic also as a neighbors share the issue of negative impacts of RES integration. RES integration influences Czech electricity market, grid management, etc. Due to this situation we consider the analysis of short-term variability of renewable production as a very important, mainly from resources adequacy point of view, to ensure stable and secure electricity supply.