Controllability | EPFL Graph Search

Controllability is an important property of a control system and plays a crucial role in many control problems, such as stabilization of unstable systems by feedback, or optimal control. Controllability and observability are dual aspects of the same problem. Roughly, the concept of controllability denotes the ability to move a system around in its entire configuration space using only certain admissible manipulations. The exact definition varies slightly within the framework or the type of models applied. The following are examples of variations of controllability notions which have been introduced in the systems and control literature:

State controllability
Output controllability
Controllability in the behavioural framework

State controllability The state of a deterministic system, which is the set of values of all the system's state variables (those variables characterized by dynamic equations), completely describes the system at any given time. In particular, n

From the electrical shunting of a loudspeaker to active impedance control

Hervé Lissek, Florian Sandoz

Variable acoustic properties can be obtained on an electroacoustic transducer’s voicing face by very basic control strategies, among which are the shunting of the loudspeaker (shortcut, variable electric load, or negative resistance disposals). It is proven that enhanced controllability and better performances can be obtained by way of hybrid feedback control, consisting in a double feedback loop, one on acoustic pressure at the diaphragm and the other on its velocity, leading to a global acoustic impedance control. The present work will describe the theory of the hybrid feedback control, by way of block diagrams aiming at visualizing the control principle, starting from the shunted loudspeaker. Simulations of performances obtained on Matlab/Simulink will then be presented, and compared to experimental results obtained on analog prototypes mounted at the end of a dedicated impedance tube. A discussion on stability will then follow, leading to concluding remarks on the disposal behavior and possible means of enhancements.

2008

Structure-preserving eigenvalue solvers for robust stability and controllability estimates

Daniel Kressner

Structured eigenvalue problems feature a prominent role in many algorithms for the computation of robust measures for the stability or controllability of a linear control system. Structures that typically arise are Hamiltonian, skew-Hamiltonian, and symplectic. The use of eigenvalue solvers that preserve such structures can enhance the reliability and efficiency of algorithms for robust stability and controllability measures. This aspect is the focus of the present work, which summarizes and extends existing structure-preserving eigenvalue solvers. Also, a new method for estimating the distance to uncontrollability in a cheap manner is presented. The structured eigenvalue algorithms described in this paper are intented to become part of HAPACK, a software package for solving structured eigenvalue problems and applications.

IEEE2006

White paper on DC technologies for Switzerland’s electricity transmission and distribution

Alexandre François Christe, Drazen Dujic, Stefan Milovanovic, Mario Paolone, Farhad Rachidi-Haeri, Reza Razzaghi, Milan Utvic, Zhaoyang Wang

Existing AC power systems, established more than a century ago, are increasingly challenged by DC technologies, enabled by significant advancements in the power electronics and related scientific fields. Three major application areas for DC transmission are established: transferring bulk power over long distances, interconnecting grids and connecting offshore wind. Medium and low voltage DC application become more appealing based on the improved controllability, more effective integration of renewable energy sources, higher power density and better compatibility with underground cables. Such technologies will be attractive for the Swiss energy transition as they might provide more effective solutions for the densification of power systems, the integration of converter-based renewable energy sources and pumped-storage plants. In order to achieve this, several research challenges, however, need to be overcome and standardization must further advance. Several academic partners from Switzerland contribute to these research problems in WP3: “Multi-Terminal AC-DC Grids and Power Electronics” within the SCCER FURIES. In this paper six major topics are presented: -“General overview of DC options” where present and future applications of DC technologies as wells as MVDC grids development issues are discussed. -“MMC-based MVDC converters” where a selection of modular multilevel converter as a platform in order to provide flexibility in addressing a multitude of applications and conversion needs is shown. Several topological adaptations are proposed, leading to novel converter topologies. -“AC/DC resonance analysis” where analysis allowing to find the resonance location and to analyzeres-onance nodes contribution to critical mode. These frequency analysis methods permit to foresee net-work frequency behavior that is becoming an important issue due to the growing number of power electronics converters in the network. -“Overview of HVDC breaker technologies” where basic requirements for fast and reliable HVDC circuit breakers as well as the differences to HVAC technology are introduced. -“HVDC circuit breakers: testing methods and challenges” where the limits of HVDC circuit breakers are explored. In this section, a flexible, modular high current source is presented. The source is intended to act as a hardware-in-the-loop test benchfor future HVDC circuit breakers, by driving highly dynamic and arbitrary current waveforms through dynamic loads (e.g. DC arc). -“Fault location principles” where the significant influence of fault location on the network security of supply and quality is drawn. A newly-developed technique which is based on the electromagnetic time reversal (EMTR) theory that can be applied to radial/meshed AC/DC power transmission or distribution networks is presented and compared to other Travelling Wave –based methods. The outputs and outlooks are drawn in order to conclude the paper.

Work Package 3 of the SCCER-FURIES2019

White paper on DC technologies for Switzerland’s electricity transmission and distribution

Alexandre François Christe, Drazen Dujic, Stefan Milovanovic, Mario Paolone, Farhad Rachidi-Haeri, Reza Razzaghi, Milan Utvic, Zhaoyang Wang

Work Package 3 of the SCCER-FURIES2019