UPCommons - E-prints UPC Universitat Politècnica de Catalunya
E-prints UPC cobreix dues finalitats: per una banda, és el dipòsit institucional de la UPC que recull els articles de revista, les comunicacions de congrés i els reports de recerca generats en les activitats de recerca del personal docent i investigador de la universitat; per l'altra, és una eina que permet accelerar la producció científica, allotjant versions de documents prèvies a la publicació en una revista o a les actes d’un congrés.
Ponències/Comunicacions de congressos
Mostrando recursos 1 - 18 de 18
An alternative discrete-time model for networked control systems with time delay less than the sampling period - Torres Guerrero, Gina; Velasco García, Manel; Martí Colom, Pau; Martín Rull, Enric Xavier; Fuertes Armengol, José Mª
The majority of existing Networked Control Systems (NCS) models are discrete-time formulations based on the exact discretization of the continuous-time linear plant over a sample interval. In the state-space formalism, standard control
textbooks suggest that a simple approach to model discrete-time LTI systems with time delay shorter or equal than the sampling
period is to extend the state vector with a new state variable representing the last control signal, which implies increasing the
order of the model by one. In this paper an alternative state-space model for discrete-time LTI systems with time delay is introduced that does not require increasing the order of...
Mixing local and distributed reactive power control for balancing inverters’ effort in grid-connected photovoltaic systems - Velasco García, Manel; Martí Colom, Pau; Camacho Santiago, Antonio; Miret Tomàs, Jaume; Castilla Fernández, Miguel
Reactive power control methods have been proven to be a successful technique for maintaining voltages of photo-voltaic (PV) distributed generators (DG) within the admissible limits without enforcing to reduce the production of active power. Usually the control goal is achieved at the expenses of stressing PV inverters unequally. As a consequence, inverters
deteriorate at different velocities. This paper presents a mixed local and distributed control strategy that aims at balancing the
effort posed by each inverter while achieving the control goal.
The local control is a drop-like method that locates inverters’voltages within the permissible voltage levels. Simultaneously,
the distributed control, making use of a...
Control strategies based on effective power factor for distributed generation power plants during unbalanced grid voltage - Camacho Santiago, Antonio; Castilla Fernández, Miguel; Miret Tomàs, Jaume; Matas Alcalá, José; Guzmán Solà, Ramon; de Sousa Pérez, Óscar; Martí Colom, Pau; García de Vicuña Muñoz de la Nava, José Luis
Unbalanced voltages in three-phase power systems is a common perturbation propagated along the grid. Distributed Generation plants have gained widespread attention due to their capability to improve power quality in a distributed manner, including voltage unbalance mitigation. A conventional control strategy to command power plants during balanced grid voltages, is the use of power factor to inject/absorb reactive power depending on grid conditions. Advanced control strategies during unbalanced grid voltages can be selected prioritizing positive or negative sequence active and reactive power. This selection determines the voltage support service and therefore can improve the voltage profile, i.e. phase-voltages can be...
Power sharing control in islanded microgrid using event driven communication - de Sousa Pérez, Óscar; Miret Tomàs, Jaume; Camacho Santiago, Antonio; Martí Colom, Pau; Guzmán Solà, Ramon
This paper presents a novel power sharing control
strategy for islanded mode microgrids (MG). The goal is to
enable renewable power sources connected to the point of com-
mon coupling (PCC) through three-phase three-wire inverters to
cooperatively feed linear and non-linear local loads. The strategy
contribution is two-fold. First, a centralized controller is designed
to facilitate the power sharing capability of all inverters by means
of data communications regardless of load changes and inverter
faults. Second, a communication protocol is designed following
an event-driven paradigm in such a way that the consumed
bandwidth is reduced. Selected simulation results show the main
features of the power sharing control strategy.
Distributed reactive power control methods to avoid voltage rise in grid-connected photovoltaic power generation systems - Martí Colom, Pau; Velasco García, Manel; Fuertes Armengol, José Mª; Camacho Santiago, Antonio; Miret Tomàs, Jaume; Castilla Fernández, Miguel
A high density of grid-connected photovoltaic (PV)
power generation systems is expected to occur in urban areas.
The connection of distributed generation (DG) may cause serious
problems in the distribution system such as voltage rise. Several
voltage control strategies exist to avoid the over-voltage at
the power grid. In particular, reactive power control methods
have been proved to successfully bring DGs voltages within the
admissible voltage range without reducing the production of
active power. In addition, the possible use of communication
infrastructure to link DGs opens up the development of new
reactive power control methods where control actions at each
DG may be decided using both local and global information.
Desarrollo integral de las competencias genéricas mediante mapas competenciales - Sánchez Carracedo, Fermín; Ageno Pulido, Alicia; Belanche Muñoz, Luis Antonio; Cabré Garcia, José M.; Cobo Valeri, Erik; Farré Cirera, Rafael; García Almiñana, Jordi; López Álvarez, David; Marès Martí, Pere; Martín Escofet, Carme; Soler Cervera, Antonia
Los planes de estudio del EEES deben diseñarse a partir de las competencias de la titulación, tanto específicas como genéricas. La universidad española tiene una amplia experiencia en trabajar y evaluar las competencias específicas, pero las competencias genéricas suponen un nuevo reto
que es preciso abordar. En este trabajo se hace una propuesta sobre cómo trabajar y evaluar, de forma global, las competencias genéricas en una titulación de Grado. La propuesta se está implantando en los estudios de Grado en Ingeniería Informática de la Facultat d’Informàtica de Barcelona. En lugar de establecer diversos niveles de competencia y asignar cada uno...
Designing a practical course in networked control systems - Fuertes Armengol, José Mª; Villa Millaruelo, Ricardo; Ayza Graells, Jordi; Marès Martí, Pere; Martí Colom, Pau; Velasco García, Manel; Yépez Castillo, José Gregorio; Torres Guerrero, Gina; Perelló, Miquel
This paper presents a hands-on course in networked control systems (NCS) to be integrated in the education of embedded control systems engineers. The course activities have a strong practical component and most of them are applied exercises to be implemented in a NCS setup. The paper describes the experimental setup and then proposes several activities that can be shaped into a course program according to the needs and diverse background of the targeted audience.
Hands-on course in networked control systems - Fuertes Armengol, José Mª; Villa Millaruelo, Ricardo; Ayza Graells, Jordi; Marès Martí, Pere; Martí Colom, Pau; Velasco García, Manel; Yepez, J.; Torres Guerrero, Gina; Perello, M.
In many industrial robotic applications there is a need to
track periodic reference signals and/or reject periodic disturbances. This
paper presents a novel repetitive control design for systems with constant
time-delays in both forward and feedback control channels. An additional
delay is introduced together with plant delays to construct an internal
model for periodic signals, and a simple proportional control is utilized
to stabilize the closed-loop system. Sufficient stability conditions of the
closed-loop system and the robustness analysis under modeling uncertainties
are studied. Experimental results are included to evaluate the
validity and effectiveness of the proposed method.
Lowering traffic without sacrificing performance in networked control systems - Martí Colom, Pau; Velasco García, Manel; Yépez Castillo, José Gregorio; Martín Rull, Enric Xavier
In Networked Control Systems (NCS), the amount of
control data exchanged between sensors, controllers and
actuators nodes highly depends on the control performance
specifications given to each networked control
loop. The periodic execution of each loop helps meeting
the control specifications while imposing a static network
traffic. This paper presents an alternative execution
mechanism for each networked control loop that permits
to dynamically lower the traffic while ensuring the same
or better control performance than the achieved by the
periodic case. Simulation results illustrate the theoretical
Qualitative analysis of a one-step finite-horizon boundary for event-driven controllers - Velasco García, Manel; Martí Colom, Pau; Yépez Castillo, José Gregorio; Ruiz Vegas, Francisco Javier; Fuertes Armengol, José Mª; Bini, Enrico
Performance optimization for networked and embedded
control systems refers to the ability of minimizing controllers’
resource utilization and/or improving control performance.
Event-driven control has been shown to be a promising
technique for minimizing controllers’ computational demands.
However, optimization of control performance for event-driven
control has not been fully addressed. For LTI plants, this
paper presents a boundary for event-driven controllers that
determines at each job execution when the next job execution
should occur in order to minimize a continuous-time quadratic
cost function while minimizing controllers’ computational demand.
Simulation results illustrate the qualitative shape of this
Networked sliding mode control of the double integrator system using the event-driven self-triggered approach - Martí Colom, Pau; Velasco García, Manel; Camacho Santiago, Antonio; Martín Rull, Enric Xavier; Fuertes Armengol, José Mª
Sliding mode control (SMC) methods rely on applying a high-frequency switching control. In networked control systems (NCS), high-frequency operations/transactions are not desirable because communication bandwidth consumption increases dramatically. This paper studies the application of event-driven self-triggered techniques to sliding mode control over networks as a means for reducing the bandwidth utilization. To this end, sliding mode control with hysteresis is adopted and control updates are forced to only occur at the hysteresis band boundary. This paper elaborates on the conditions that must be fulfilled in order to ensure such operation for the case of the double integrator system. Simulation results...
Synchronizing sampling and actuation in the absence of global time in networked control systems - Martí Colom, Pau; Camacho Santiago, Antonio; Velasco García, Manel; Marès Martí, Pere; Fuertes Armengol, José Mª
The successful operation of Networked Control Sys-
tems (NCS) requires employing appropriate approaches
for dealing with network induced time delays, i.e. time
intervals elapsed from consecutive sampling and actua-
tion operations. Effective approaches often require to im-
pose periodic execution for the sampling and/or actuation
operations, enforcing synchronized constant time delays.
And considering that sampling and actuation is performed
in different nodes, global time between nodes achieved by
clock synchronization is the standard assumption or strat-
egy that enables such synchronized operations. This pa-
per presents a technique that permits to implement these
synchronized operations in NCS in the absence of global
time. Experimental results corroborate the effectiveness
of the presented approach.
Efficient utilization of bus idle times in CAN-based networked control systems - Martí Colom, Pau; Camacho Santiago, Antonio; Velasco García, Manel; El Mongi Ben Gaid, Mohamed
This paper presents a novel approach to networked control systems (NCS) analysis
and design that provides increased control performance for a set of control loops that exchange control data over the Controller Area Network (CAN). This is achieved by enabling the following functionality for each control loop: first, standard periodic messaging is guaranteed to ensure stability, and second, non-periodic additional messaging is added whenever the bus is idle in such a way that the aggregated control performance for all control loops is improved. The proposed approach, named Maximum Difference (MD) policy, is computable in a distributed manner, and is practically feasible...
One-step finite horizon boundary with varying control gain for event-driven networked control systems - Yépez Castillo, José Gregorio; Velasco García, Manel; Martí Colom, Pau; Martín, Enric Xavier; Fuertes Armengol, José Mª
Recent research has shown that event-driven control requires less samples than time-driven (periodic) control. Consequently, event-driven control applied to Networked Control Systems (NCS) is a good approach for alleviating controllers bandwidth demands and reducing overall network traffic. Following this trend, this paper presents an execution rule for event-driven networked controllers that at each job
execution aims at postponing the next job execution while applying an appropriated controller gain considering each varying sampling interval that applies at run time. This method permits to dynamically lower the generated traffic for each networked control loop while ensuring the same or better
control performance than the...
Invariant manifolds as boundaries for event-driven control systems - Velasco García, Manel; Martí Colom, Pau
In event-driven control approaches, control updates are triggered by event conditions that are often characterized by different types of boundaries defined in the state-space domain. In this paper we define an event-driven control approach where boundaries are manifolds characterized as invariant sets. With such a boundary, a control update will only be activated when the system trajectory intersects the
boundary. And the system trajectory must intersect again the boundary to activate the next control update. For linear systems, we derive an scaling property for these boundaries that permit to regulate the accuracy of the control without altering the timing offered by...
Self-triggered networked control systems: an experimental case study - Camacho Santiago, Antonio; Martí Colom, Pau; Velasco García, Manel; Lozoya, Camilo; Villa Millaruelo, Ricardo; Fuertes Armengol, José Mª; Griful Ponsati, Eulàlia
A self-triggered controller is characterized, in general, by a non-periodic sequence of job activations. And each job
execution, apart from performing sampling, control algorithm computation and actuation, calculates the next job activation time as a function of the plant state. This paper describes the implementation of self-triggered controllers in networked
control systems (NCS). The implementation corroborates that self-triggered control can be used for minimizing bandwidth utilization while providing similar control performance than periodic controllers.
Embedding Kalman techniques in the one-shot task model when non-uniform samples are corrupted by noise - Lozoya, Camilo; Romero, Julio; Martí Colom, Pau; Velasco García, Manel; Fuertes Armengol, José Mª
The performance of several closed-loop systems whose controllers concurrently execute in a multitasking realtime
system may be deteriorated due to timing uncertainties in tasks´executions, problem known as scheduling jitters. Recently,
the one-shot task model, that combines irregular sampling, a predictor observer, and strictly periodic actuation, was presented in order to remove the negative effects of jitters. However, its successful application required noise-free samples.
In this paper we extend the one-shot task model to the case of noisy measurements. In particular, we embed a Kalman filter into the model taking into account that the available measurements are not periodic. This poses the problem of...
Minimizing control cost in resource-constrained control systems: from Feedback scheduling to event-driven control - Lozoya, Camilo; Martí Colom, Pau; Velasco García, Manel
This paper evaluates approaches aimed at minimizing aggregated control cost of a set of controllers that concurrently execute sharing limited computing resources. The
evaluation focuses on feedback scheduling and event-driven control methods. The performance results drive the analysis to
explore self-triggered controllers in the context of minimizing control cost when given a fixed amount of computing resources.
This leads to the formulation of an optimization problem, that for given example, is numerically solved. The solution helps understanding the behavior of self-triggered controllers.