Instal·lacions elèctriques

Presentem un text d'instal·lacions elèctriques pensat com a eina d'estudi per a estudiants universitaris de titulacions no elèctriques. S'inicia el desenvolupament amb temes referents al càlcul i protecció de les instal·lacions; tot seguit s'introdueixen conceptes bàsics de luminotècnia aplicats a l'enllumenat elèctric viari i finalitzat amb una visió general de problemes, cada cop més freqüents, causats per la presència de càrregues no lineals en les instal·lacions.3a ed

Màquines elèctriques

S'ha volgut donar un tractament tan simple com ha estat possible intentant abastar les tipologies de màquines més freqüents. Així s'han obviat les demostracions conduents a l'obtenció d'alguns esquemes equivalents pensant que aquest text està adreçat a usuaris d'aquestes màquines i no a dissenyadors de sistemes elèctrics. S'ha cregut convenient tractar amb més profunditat els transformadors, tant per la seva àmplia difusió en tot tipus d'instal·lacions com perquè serveix de base per a la comprensió d'altres màquines.2a ed

Understanding the three and four-leg inverter Space Vector

This paper shows a new point of view of the classical voltage space vectors and its implications on three and four-leg converters. It is easy to find in the literature, authors using bi-dimensional and threedimensional representations of the converter states. Nonetheless, the literature rarely specifies what these spaces represent. Therefore, this paper proposes a wide analysis of the state voltages and its references for three-leg, three-leg four-wire and four-leg inverters, in favour of understanding the space vector behaviour under three and four-wire scenarios.Postprint (published version

Sensorless control of a power converter for a cluster of small wind turbines

This study presents a new sensorless control for small wind turbine clusters with a single power converter with a direct torque control algorithm. The proposed system consists of a wind farm connected to a back-to-back power converter that interfaces the wind farm with the AC grid. The studied wind turbines are based on fixed-speed wind turbines equipped with squirrel cage induction generators with individual pitch control. The presented structure permits to reduce the number of converters and allows to accomplish the grid codes (fault ride through capability and reactive power support). Furthermore, the generated active power can be reduced according to grid operator requirements. The presented control scheme can be applied to wind turbine repowering projects, wind farms connected to a microgrid, even, new small onshore and offshore power plants. The system performance and stability is studied and validated by means of dynamic simulations.Postprint (author's final draft

Circuits elèctrics

Descripció del recurs: 23 de setembre de 2014Reimpressions: 2013Presentem un text de teoria de circuits pensat com a eina d'estudi per a estudiants universitaris de titulacions no elèctriques. El contingut comprèn des de circuits en corrent continu fins a sistemes trifàsics en règim permanent. En tractar els sistemes trifàsics es fa un èmfasi especial en els sistemes equilibrats amb consums simètrics atès que aquesta és la situació més freqüent

Circuits elèctrics

Aquest text de teoria de circuits ha estat concebut com a eina d'estudi per a estudiants universitaris de titulacions no elèctriques. El contingut comprèn des de circuits en corrent continu fins a sistemes trifàsics en règim permanent. Quan es tracten els sistemes trifàsics es fa èmfasi especialment en els sistemes equilibrats amb consums simètrics, atès que aquesta és la situació més freqüent.3a e

Composed Index for the Evaluation of Energy Security in Power Systems within the Frame of Energy Transitions—The Case of Latin America and the Caribbean

Energy transitions are transforming energy systems around the globe. Such a shift has caused the power system to become a critical piece of infrastructure for the economic development of every nation on the planet. Therefore, guaranteeing its security is crucial, not only for energy purposes but also as a part of a national security strategy. This paper presents a multidimensional index developed to assess energy security of electrical systems in the long term. This tool, named the Power System Security Index (PSIx), which has been previously used for the evaluation of a country in two different time frames, is applied to evaluate the member countries of the Latin American Energy Organization, located within the Latin America and the Caribbean region, to measure its performance on energy security. Mixed results were obtained from the analysis, with clear top performers in the region such as Argentina, while there are others with broad areas of opportunity, as is the case of Hait

Performance of fixed speed wind turbines under system frequency deviations

This paper studies the impact of system frequency deviations on the operation of fixed speed induction generators used in wind turbine generation systems(WTGS). It presents an analytic method to predict the angular speed, torque and current during and after a frequency disturbance. The proposed method can be used to evaluate the operation limits of the WTGS during frequency deviations.Postprint (published version

Passive and Active Methods of Islanding for PV systems

This paper presents a review of some techniques for islanding detection, especially by using inverter based DG applications and it also focuses on several islanding detection methods for a single- phase current-control voltage inverter working with a PV system connected into the grid. It is deliberated a single-phase inverter with maximum power of 5 kW. Islanding detection methods are investigated, simulated and evaluated in MATLAB / SIMULINK.Peer ReviewedPostprint (author’s final draft

A hybrid energy storage solution based on supercapacitors and batteries for the grid integration of utility scale photovoltaic plants

This paper presents a 2-level controller managing a hybrid energy storage solution (HESS) for the grid integration of photovoltaic (PV) plants in distribution grids. The HESS is based on the interconnection of a lead-acid battery pack and a supercapacitor pack through a modular power electronics cabinet. The inclusion of the HESS into the PV plant –and not an state-of-the-art energy storage system based on a single technology–, is motivated by the diversity of technical requirements for the provision of the services of grid peak power shaving and PV output power ramp limitation. The 2-level controller ensures a synergistic exploitation of the two storage technologies aiming for an optimal service level of the HESS and minimum battery degradation. The higher level of the controller is based on a mathematical optimization problem that solves with the optimal schedule of the storage technologies for peak power shaving purposes. The power setpoints of this optimization are then complemented by a real time controller managing PV plant output ramp limitation. The HESS performance and associated controller has been proved effective through two case studies. The first one adopts a 6.6 MW PV plant including a HESS solution combining a 5.5 MWh and 2.64 MW lead-acid battery pack with a 0.25 MWh and 1.32 MW supercapacitor pack. The second one reports experimental data from an analogous scenario scaled down to kW level and using a laboratory scale prototype for the HESS. All in all, the hardware and software solutions proposed in this paper contribute to a feasible exploitation of multi-purpose energy storages targeting the needs of renewables' and distribution system operators.Peer ReviewedPostprint (published version