Grid Codes Certification by Simulation

Abstract

Reliance on fossil fuels as the primary source of energy has led to a significant rise in greenhouse emissions, which has become an environmental threat. Therefore, there has been an increasing trend towards utilizing alternative inverter-based distributed energy resources in recent years. Incorporating distributed energy resources is the key to a sustainable energy sector. However, integrating distributed energy sources into the grid presents a major challenge because of their fluctuating and intermittent nature, which can lead to grid instability. Therefore, grid codes and standards have been developed to ensure the reliability and safety of the grid. The current certification tests and on-site commissioning are costly, time-consuming, and may not cover all grid code requirements. In addition, compliance certification tests by a third party within a short time are highly required. Therefore, simulation tests help bridge the gap between their type tests and on-site tests. This study aims to establish standardized, efficient compliance testing for grid code simulation using MATLAB Simulink. By improving the testing process and narrowing the gap between type tests and on-site testing, this thesis paves the way. This master’s thesis provides a method for testing grid code compliance based on EN50549-1, EN50549-2, and EN50549-10 standards. The study focuses on key aspects such as under voltage- ride-through and over-voltage ride-through. Two grid code tests were conducted by MATLAB Simulink. The first test assesses the ability of the inverter to withstand over-voltage and under- voltage events, by dividing the OVRT and UVRT curves into three zones and then creating voltage rise and dip scenarios. Two tests were conducted for each zone, and the simulation model showed that the inverter is compatible with the standards. The second test evaluates the com- patibility of the inverter with frequency variations. The test was conducted by increasing the frequency to a value higher than the acceptable thresholds to ensure that the frequency relay would operate and disconnect the grid. The model was executed in real-time using the OPAL-RT simulator, and related grid code compliance testing conducted using HIL system was highlighted in this master thesis.