Dynamic Characterization of Typical Electrical Circuits via Structural Properties

The characterization of a class of electrical circuits is carried out in terms of both stability properties and steady-state behavior. The main contribution is the interpretation of the electrical topology (how the elements that conform the circuits are interconnected) in terms of mathematical properties derived from the structure of their models. In this sense, at what extent the topology by itself defines the dynamic behavior of the systems is explained. The study is based on the graph theory allowing capturing, departing from the well-known Kirchhoff laws, the topology of the circuits into several matrices with specific structure. The algebraic analysis of these matrices permits identifying conditions that determine whether the system is stable in the sense of Lyapunov and the kind of steady-state behavior that it exhibits. The approach is mainly focused on typical topologies widely used in practice, namely, radial, ring, and mesh networks

Distributed Energy Resources Integration in AC Grids: a Family of Passivity-Based Controllers

[EN] This paper presents the design and application of passivity–based control theory for distributed energy resources (DERs) integration through voltage source converters (VSC) in ac single–phase grids. The Hamiltonian representation of these grids facilitates the development of passive controllers that guarantee stability in the sense of Lyapunov for their closed–loop operation. The non–autonomous dynamic modeling of these systems is transformed into an incremental model, which allows solving the tracking as a regulation problem. The main contribution of this paper is in the ability to control the active and reactive power transference between DERs and the ac single–phase grid depending on the availability of the primary energy resource and the capacity of the converters. Simulations results show that all proposed controllers attain the control objective, reaching the same dynamic performance as classical proportional–integral controllers and guaranteeing asymptotic stability. All simulations are developed under the MATLAB/Simulink environment through the SimPowerSystems tool.[ES] En este artículo se presenta el diseño y la aplicación de la teoría de control basada en pasividad para la integración de recursos energéticos distribuidos (REDs) a través de convertidores controlados por voltaje en redes monofásicas de corriente alterna. La representación Hamiltoniana de estos sistemas facilita el desarrollo de controladores pasivos que garantizan estabilidad en el sentido de Lyapunov para su operación en lazo cerrado. El modelado dinámico no autónomo de estos sistemas es transformado en un modelo incremental, el cual permite resolver el problema de seguimiento de trayectorias como un problema de regulación. La principal contribución de este trabajo radica en la capacidad de controlar el flujo de potencia activa y reactiva entre los REDs y la red eléctrica en función de la disponibilidad del recurso energético primario y la capacidad de los convertidores. Los resultados de simulación muestran que todos los controladores pasivos propuestos logran el objetivo de control, alcanzando el mismo desempeño dinámico que los controladores proporcionales integrales clásicos, garantizando estabilidad asintótica. Todas las simulaciones son desarrolladas bajo el entorno MATLAB/Simulink a través de la librería SimPowerSystems.Este trabajo ha sido financiado parcialmente por la Convocatoria de Doctorados Nacionales 757 de 2015 del Departamento Administrativo de Ciencia, Tecnología en Innovación del gobierno de Colombia (COLCIENCIAS). También, parte de este trabajo ha sido financiado por DGAPA–PAPIIT con el proyecto IN116516.Montoya, OD.; Gil-González, W.; Avila-Becerril, S.; Garces, A.; Espinosa-Pérez, G. (2019). Integración de REDs en Redes AC: una Familia de Controladores Basados en Pasividad. Revista Iberoamericana de Automática e Informática. 16(2):212-221. https://doi.org/10.4995/riai.2018.10666SWORD21222116

Output-feedback global tracking control of robot manipulators with flexible joints

International audienceWe present a controller for flexible-joint robots without link velocity measurement. Our main result consists in a simple controller of the type proportional-derivative plus feedforward and a series of cascaded filters; the control design is reminiscent of classical backstepping control. To avoid the assumption that link velocities, accelerations and jerks are measured, we use approximate differentiation. The originality of our work lays in establishing uniform global asymptotic stability for the closed-loop system

A Separation Principle for Underactuated Lossless Lagrangian Systems

International audienceWe study under-actuated Lagrangian systems without dissipative forces, augmented by a chain of integrators. For such systems, we solve the open problem of global tracking control via position measurements only; strictly speaking, we establish uniform global asymptotic stability for the closed loop system. As a corollary, we obtain an original statement for flexible-joint robots, which closes a long-standing open problem of output feedback nonlinear control

A Hamiltonian control approach for electric microgrids with dynamic power flow solution

In this paper, a control scheme for islanded electric microgrids is proposed. Exhibiting a dynamical structure and based on passivity, cascaded systems, and input-to-state stability arguments, the asymptotic stability properties of the closed-loop system are formally established to guarantee that voltage regulation and a power network balance are achieved. In contrast to other approaches, the controller design considers the differential–algebraic structure of the system obtained by the explicit inclusion of the network's dynamic, the existence of both a grid-forming and grid-following nodes, and the highly nonlinear structure of the power balance equations

Consensus control of flexible joint robots

International audienceSynchronization of networks composed by fully-actuated robot manipulators has received a lot of attention from the control theory community. Unfortunately, the case of under-actuated robots has not been deeply studied. The aim of this paper is to extend previous results reported by the authors [2] addressing the particular (but of practical interest) case of networks composed by flexible-joint robots. The main feature of the contribution is to consider a change of coordinates, first introduced in [1], to solve the consensus problem assuming the existence of unknown delays in the communication channels. The extensions consist in: the presentation of a control scheme that, in contrast to the one considered in [2], does not require knowledge of the initial conditions; the proof that the controller can also be implemented in Cartesian coordinates; and the statement of the stability properties adopting a Cascaded systems perspective. The usefulness of the contribution is illustrated through numerical simulations