GR-DCS - Sistemes Distribuïts de Control
http://hdl.handle.net/2117/7275
2015-10-04T03:37:48ZToward new controller design paradigms in networked control systems
http://hdl.handle.net/2117/27568
Toward new controller design paradigms in networked control systems
Torres Guerrero, Gina; Velasco García, Manel; Martí Colom, Pau; Fuertes Armengol, José Mª
One of the main concerns in the design of networked control systems (NCS’s) is the inherent delays induced by the networking infrastructure. Rather than considering delays as a threat, delays may be considered as an opportunity for novel controller design procedures, where delays become a design parameter. The benefits may range from easier and cheaper implementations to improved performance. To enable procedures where the explicit specification of a delay may be profitable, al- ternative models for a discrete-time LTI system with an arbitrary delay used for controller design must be investigated. This paper presents a modeling effort different than the common approach of extending the state-space model with new state variables. The new model is also capable of representing the same system with a delay but using a state-space modeling structure that keeps the original system order. The focus of the paper is to show that both models are equivalent. A direct consequence is that it will be possible to design a controller for a system without delay in such a way that the closed loop system behaves like having a delay. In other words, a relation between desired control performance (via e.g. closed-loop system poles), controller, and delay is established, which provides a new design criterion for NCS
2014-01-01T00:00:00ZDeveloping professional skills at tertiary level: A model to integrate competencies across the curriculum
http://hdl.handle.net/2117/25103
Developing professional skills at tertiary level: A model to integrate competencies across the curriculum
Sánchez Carracedo, Fermín; Soler Cervera, Antonia; López Álvarez, David; Martín Escofet, Carme; Ageno Pulido, Alicia; Belanche Muñoz, Luis Antonio; Cabré Garcia, José M.; Cobo Valeri, Erik; Farré Cirera, Rafael; García Almiñana, Jordi; Marès Martí, Pere
In the context of the European Higher Education Area, curriculum design needs to be based on the defined competencies of each degree programs, including both domain specific and professional competencies. In this educational context, developing students’ professional skills poses a new challenge we need to face. The present work proposes a model to globally develop professional skills in an Engineering degree program. Based on competency maps, this model allows careful analysis, revision and iteration for an effective integration of professional skills. We define each competency in terms of “dimensions” (or sub-skills), which are further defined according to three-level objectives. Competency maps are built showing the specific graded objectives, which allows to integrate them most finely into degree subjects. A global competency map is also designed including the objectives to be achieved throughout the degree. This global map becomes a useful tool for curriculum designers and coordinators. It allows them to optimize the workload, and to make adjustments most effectively, helping students develop the defined competencies as a global comprehensive experience. To illustrate our model, we explain how it has been implemented to integrate “Communication skills” into subjects, and how the model has been applied to assess “Appropriate attitude towards work” skills.
2014-01-01T00:00:00ZLTI ODE-valued neural networks
http://hdl.handle.net/2117/24573
LTI ODE-valued neural networks
Velasco García, Manel; Martín Rull, Enric Xavier; Angulo Bahón, Cecilio; Martí Colom, Pau
A dynamical version of the classical McCulloch & Pitts’ neural model is introduced in this paper. In this new approach, artificial neurons are characterized by: i) inputs in the form of differentiable continuous-time signals, ii) linear time-invariant ordinary differential equations (LTI ODE) for connection weights, and iii) activation functions evaluated in the frequency domain. It will be shown that this new characterization of the constitutive nodes in an artificial neural network, namely LTI ODE-valued neural network (LTI ODEVNN), allows solving multiple problems at the same time using a single neural structure. Moreover, it is demonstrated that LTI ODEVNNs can be interpreted as complex-valued neural networks (CVNNs). Hence, research on this topic can be applied in a straightforward form. Standard boolean functions are implemented to illustrate the operation of LTI ODEVNNs. Concluding the paper, several future research lines are highlighted, including the need for developing learning algorithms for the newly introduced LTI ODEVNNs.
2014-05-01T00:00:00ZMixing local and distributed reactive power control for balancing inverters' effort in grid-connected photovoltaic systems
http://hdl.handle.net/2117/24370
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 photovoltaic (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 communication infrastructure, is in charge of driving the DG system to the point where all connected inverters inject the same current, thus balancing the stress between them.
2013-01-01T00:00:00ZDe la farola urbana hacia un elemento urbano multifuncional
http://hdl.handle.net/2117/24181
De la farola urbana hacia un elemento urbano multifuncional
Ruiz, Fèlix; Farré, Josep; Martí Colom, Pau; Martínez Antúnez, Nora Isabel; Llorens Garcia, Ariadna
Se està produciendo un cambio de paradigma, un cambio de concepto de la farola tradicional, transformándose en otra cosa diferente, en el nodo urbano. Esto supone un nuevo paso en la línea de las smart cities. Los autores de este artículo nos describen cómo funcionan estas nuevas farolas
2014-01-01T00:00:00ZHolistic indices for productivity control assessment, applied to the comparative analysis of PID and fuzzy controllers within an Isasmelt furnace
http://hdl.handle.net/2117/23378
Holistic indices for productivity control assessment, applied to the comparative analysis of PID and fuzzy controllers within an Isasmelt furnace
Ojeda Sarmiento, Juan Manuel; Fuertes Armengol, José Mª; Griful Ponsati, Eulàlia
This research aims to contribute to the analysis of control performance assessment in extractive metallurgy. Productivity-based indices are proposed in addition to current measuring techniques. Such criteria are employed to compare conventional PID and fuzzy-based controllers in copper smelting. This process is mathematically modeled in order to be simulated. The comparison confirms a better performance of the fuzzy controller in dealing with the molten bath temperature within an Isasmelt furnace. In normal operating conditions (online tests), the proposed controller achieves a consistent mean square relative error reduction of 72% between measured values and the temperature setpoint and standard deviation of approximately 60% (from 27.8 degrees C to 11.1 degrees C). The productivity criteria establish a lower consumption of raw materials (13%) and energy supply (29%).
2014-02-01T00:00:00ZEl Node urbà : Canvi de concepte del fanal cap a element urbà multifuncional en smart cities
http://hdl.handle.net/2117/23284
El Node urbà : Canvi de concepte del fanal cap a element urbà multifuncional en smart cities
Ruiz, Fèlix; Farré, Josep; Martí Colom, Pau; Martínez Antúnez, Nora Isabel; Llorens Garcia, Ariadna
2014-06-01T00:00:00ZAn alternative discrete-time model for networked control systems with time delay less than the sampling period
http://hdl.handle.net/2117/22838
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 the model. The relation between both the standard model and the new model
is established, and the potential benefits of the new model with respect to the standard one are discussed. Numerical examples illustrate the concepts discussed throughout the paper.
2013-01-01T00:00:00ZMixing local and distributed reactive power control for balancing inverters’ effort in grid-connected photovoltaic systems
http://hdl.handle.net/2117/21470
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 communication infrastructure, is in charge of driving the DG system to the point where all connected inverters inject the same current, thus balancing the stress between them.
2013-01-01T00:00:00ZControl strategies based on effective power factor for distributed generation power plants during unbalanced grid voltage
http://hdl.handle.net/2117/21151
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 properly supported and voltage imbalance simultaneously corrected. Based on the definition of effective power factor in IEEE 1459 Standard, the reactive power needed for any control strategy is obtained and the resulting effects are described.
2013-01-01T00:00:00Z