DSpace Collection:http://hdl.handle.net/11422/902024-03-28T18:06:52Z2024-03-28T18:06:52ZRedespacho termelétrico através de avaliação de regiões de segurança em tempo realMelo, Francisco Dalmir Santiago dehttp://hdl.handle.net/11422/217782023-12-21T03:02:04Z2020-10-01T00:00:00ZTitle: Redespacho termelétrico através de avaliação de regiões de segurança em tempo real
Author(s)/Inventor(s): Melo, Francisco Dalmir Santiago de
Advisor: Lima, Antonio Carlos Siqueira de
Abstract: The optimization of the operational cost of large-scale electric power systems is the subject of academic research to improve planning and control operations in real time, in order to obtain the appropriate amounts of generation from each plant to supply demand at every moment without compromise dynamic security in the face of contingencies, what is called economic dispatch. In Brazil, a country with a privileged predominance of hydroelectricity, one of the thermoelectric dispatches occurs exclusively to increase the electrical safety of operation of the Brazilian Interconnected System (SIN), regardless of the operational cost of the thermoelectric plants. In practice, this can compromise economic dispatch, since the conditions observed in real time are often not different from those considered by the operation planning. In this context, this dissertation presents the use of the safety assessment tool to perform thermoelectric redispatch for complete grid and altered grid by contingency in real time. The calculation of dynamic safety regions in real time using ORGANON is based on the graphical estimation of new points of operation, prioritizing operational safety to increase or reduce the use of thermoelectricity. The successive analyzes of the safety regions simulated with the thermoelectric redispatches considered consist of an empirical iterative algorithm. There was satisfactory application of this methodology in a Brazilian test system of 107 bars and in an electrical area of the SIN, both for complete grid and an altered grid. This research encourages studies of new practices that converge to obtain an economic dispatch updated in real time, with the intention of using the system more efficiently and reducing tariffs to the final consumer.
Publisher: Universidade Federal do Rio de Janeiro
Type: Dissertação2020-10-01T00:00:00ZAmplificador operacional de transcondutâcia totalmente diferencial com alta linearidade e circuito de compensação de modo comumFreitas, João Pedro Gonçalveshttp://hdl.handle.net/11422/217752023-12-21T03:02:04Z2019-03-01T00:00:00ZTitle: Amplificador operacional de transcondutâcia totalmente diferencial com alta linearidade e circuito de compensação de modo comum
Author(s)/Inventor(s): Freitas, João Pedro Gonçalves
Advisor: Soares, Carlos Fernando Teodósio
Abstract: In this work, we present the design of a fully differential Operational Transcon- ductor Amplifier (OTA) with high linearity, based on the Folded Flipped Voltage Follower (FFVF) Topology. This structure was developed and applied on a 3a or- der low-pass Gm − C filter, based on the Chebyshev’s aproximation with a cutoff frequency of 300 kHz. Besides that, the OTA has low differential offset and it is integrated with a common mode feedback compensation circuit, to eliminate the common mode voltage at the output nodes. The project was implemented in a 0.35 μm Complementary Metal-Oxide-Semiconductor (CMOS) technology and op- erates at a + −1.5 V power supply.
Publisher: Universidade Federal do Rio de Janeiro
Type: Dissertação2019-03-01T00:00:00ZSimulação de máquinas supercondutoras de fluxo aprisionado com fitas de segunda geraçãoSantos, Bárbara Maria Oliveirahttp://hdl.handle.net/11422/217732023-12-21T03:02:04Z2019-03-02T00:00:00ZTitle: Simulação de máquinas supercondutoras de fluxo aprisionado com fitas de segunda geração
Author(s)/Inventor(s): Santos, Bárbara Maria Oliveira
Advisor: Andrade Junior, Rubens de
Abstract: This dissertation presents the first transient finite element simulations of two new topologies of superconducting trapped-flux machines with second generation tapes: one machine with spiral stacks and one, proposed by this work, with double crossed loops. The two computational models used, H and hybrid A-φ-H formulations, are presented and discussed. The implementation of the models is analyzed, as well as the machines work conditions in each simulation. The results obtained in the spiral stack machine are compatible with the experimental data measured in the prototype.
Publisher: Universidade Federal do Rio de Janeiro
Type: Dissertação2019-03-02T00:00:00ZControle híbrido em cascata baseado em passividadeRibeiro, Rodolpho Costahttp://hdl.handle.net/11422/217532023-12-21T03:02:04Z2019-03-02T00:00:00ZTitle: Controle híbrido em cascata baseado em passividade
Author(s)/Inventor(s): Ribeiro, Rodolpho Costa
Advisor: Costa, Ramon Romankevicius
Abstract: This dissertation presents a passivity-based cascade hybrid control law whose goal is to ensure contact stability between the end-effector of an industrial manipu- lator and an unknown compliant surface on which it performs an interaction task. The cascade control law consists on two nested control loops. In the inner loop, a joint space inverse dynamics algorithm is used to make the manipulator behave kinematically. In the outer loop, an operational space kinematic position/force hy- brid control law is used so that the end-effector follows a desired position trajectory on the surface while exerting a desired contact force on the orthogonal direction to it at all times. A kinematic orientation control law is also used so that the end-effector always stays aligned with the orthogonal direction. In theory, this control allows tracking of the position, force and orientation ref- erences. However, due to practical aspects of implementation in a real manipulator, the contact between the end-effector and the surface may become unstable and large contact forces may be exerted, damaging both the manipulator and the sur- face. Many of these destabilizing factors can be attributed to the force sensor, for example, its measurement delay. The goal of the passivity control is to prevent this instability. An energy observer is introduced to monitor the energy dissipated by the system and, if loss of passivity is detected at any time, a passivity controller acts to increase its impedance so that it dissipates a larger amount of energy until passivity, and consequently stability, is recovered.
Publisher: Universidade Federal do Rio de Janeiro
Type: Dissertação2019-03-02T00:00:00Z