Felix Berkel

Load-frequency control, economic dispatch and unit commitment in smart microgrids based on hierarchical model predictive control

This paper presents an energy management system for smart microgrids (MGs) based on hierarchical model predictive control (HiMPC). The HiMPC comprises two levels. On the lower level load-frequency control is realized on a short time scale while on the upper level economic dispatch and unit commitment are implemented on a long time scale. HiMPC allows integrating these functionalities over different time scales while regarding constraints (e.g. power ratings) and predictions (e.g. on renewable generation and load) as well as rejecting disturbances (e.g. due to volatile renewable generation) based on a systematic model- and optimization-based design. The HiMPC problem is formulated as a mixed-integer linear program which can be solved efficiently using standard solvers. The energy management system is evaluated for a smart MG of a company with a focus on grid integration of electric vehicles.

Event-based distributed control of dynamically coupled and constrained linear systems

In this paper, a novel event-based distributed control strategy for a set of dynamically coupled discrete-time LTI plants is proposed. To avoid unnecessary communication among the distributed control system, each plant with its local controller is equipped with an event generator deciding locally whether new state measurements must be sent or not. Via a tuning parameter and a codesign of event generator and controller, the designer can adjust an eligible trade-off between control performance and communication utilization. Further state and input constraints as well as constraints on the communication topology can be included into the codesign. With a quadratic event-triggering law and the socalled S-procedure the codesign can be formulated as an LMI optimization problem which guarantees asymptotical stability of the closed-loop system and compliance with the constraints. The effectiveness of the approach is evaluated for distributed control of a set of mechanically coupled inverted pendulums.

A privacy preserving negotiation-based control scheme for low voltage grids

In this paper a voltage control strategy based on the integration of dynamic optimal power flow into the model predictive control framework is presented. An approximated power flow model for radial distribution systems is introduced to incorporate it into an online control method. Moreover, the two main problems arising from distributed generation in low voltage grids are addressed. These are the overvoltages at the end of long lines and the overcurrents due to high load and generation. The voltage control problem is solved with a distributed model predictive control approach where different local controller negotiate an optimal power dispatch subject to voltage and current constraints. The main advantage is that although the negotiation approach keeps sensitive data private, the communication effort is low and limited.

Distributed control of constrained linear systems using a resource aware communication strategy for networks with MAC

In order to apply distributed control for practical applications, some important aspects must be taken under consideration. First, the communication network is subject to transmission delays and to medium access constraints. Second, it can also be utilized for other non-control tasks. Therefore, a resource-aware control and scheduling codesign strategy for a set of dynamically coupled and input/state constrained subsystems is proposed in this paper. Each subsystem is described by a discrete-time linear state equation plus an additional term that represents the coupling with other subsytems. The associated input and state constraints are expressed in a more general form as linear inequalities including box constraints as a special case. The codesign problem is formulated for the entire collection of all subsytems as an LMI optimization problem with the objective of maximizing the set of admissible initial state values. The effectiveness of the codesign strategy is evaluated for distributed control of a set of mechanically coupled inverted pendulums.

Integrated energy and parking management for parking areas with electric vehicles

On the one hand electric vehicles are seen as a key technology for an environmentally friendly and carbon neutral mobility, while on the other hand they impose new challenges on todays electric power grid. This paper deals with a combination of energy and parking management for a parking area with electric vehicles to reduce the impact of EVs on the electric power grid and efficiently use charging infrastructure. In total two different operation methods are proposed both using mixed integer programming.