Advanced power converters for universal and flexible power management in future electricity network -  Report on Control Strategies

The present document summarizes the work that has been done in Work Package 5 (WP5) where the focus is on modelling and control of the Uniflex-PM system. The models used in the WP5 are described in detail. Since the grid synchronization and monitoring techniques play an important role in the control of the Uniflex-PM system, a special attention is paid to this topic. The events in the electrical networks are treated in detail in terms of definitions and classifications from standards, origins, and surveys in different countries. A summary of the grid synchronization and monitoring methods is also given with a special focus on Phase Locked Loop systems. The response of the single and three phase PLLs is analyzed under different grid events. Four control strategies are studied in the WP5, namely: synchronous reference frame control, predictive control stationary reference frame control with Proportional Resonant current controllers and natural reference frame control with Proportional Resonant current controllers. These control strategies are evaluated under different grid conditions such as voltage excursions, voltage unbalances, phase jumps and shortcircuits in the Point of Common Coupling. Finally, some conclusions and recommendations for future work are given.