STABEEL2: Stability of decentralized generators in the electrical power supply network when providing ancillary services - extension

• Applicants: Professor Dr.-Ing. Klaus Röbenack; Professor Dr.-Ing. Peter Schegner
• Subject Area: Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 442893506

With the goal of CO2-neutral energy provision and the resulting high dynamics in the growth of decentralized energy resources (DERs) based on wind and solar energy, high challenges are facing grid operation - especially taking into account the current tense background of energy policy. All operating strategies associated with this, or more specifically with voltage regulation, must satisfy stability requirements. In today's normal operation, different types of voltage support can be found in parallel; for example, the specification of centrally optimized setpoints and Q(V)-characteristic control as a form of indirect voltage control. The main idea here is the adaptive provision of reactive power in order to be able to influence the grid voltage locally on the one hand and to provide the reactive power required to operate the grid on the other. However, the impact of all control interventions on the grid is not taken into account by the individual DERs. Possible interactions of Q(V)-characteristic controls are classified as aspects of (short-term) voltage stability or as slow- interaction converter-driven stability. The decentralized control approach leads to theoretically interesting and challenging control engineering issues, which could already be addressed in parts in the previous project. Based on the research work of the STABEEL project, the following research areas are formulated: a) the usage of the degree of freedom in the Q(V) control by considering the negative sequence to improve the voltage quality; b) the combination of superimposed Q(V) control and subordinated current control to a novel I(V) control for more efficient voltage support and simplified analysis of the resulting control loops; c) the replacement of communication channels by observer-based state estimates for the implementation of modern distributed control approaches in current networks. The project is structured in three thematic complexes (TC). At the beginning, the applicants will address the completion of the TC "Detection of inconsistencies in control systems". The evaluation of control inconsistencies of DERs by pattern recognition is performed.The search for error patterns is to be supported, among other things, with the help of neural networks. The second TC is dedicated to the further development of Q(V) control. Starting from a transformation of the classical Q(V)-characteristic into a "linearizing" one, the concept of the I(V)-control shall be developed. The interaction between Q(V) and I(V) control is to be considered, evaluated and experimentally verified. The third TC focuses on networked controller structures. Here, the design of controller structures under the assumption of ideal as well as disturbed communication conditions is in the interest. The final part is an investigation on the replacement of communication channels by an observer-based estimation.

• DFG Programme: Research Grants