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- Simulation of offshore wind system with two-level converters: HVDC power transmissionPublication . Seixas, Mafalda; Melício, Rui; Mendes, Victor; Pousinho, Hugo Miguel InácioA new integrated mathematical model for the simulation of offshore wind energy conversion system performance is presented in this paper. The mathematical model considers an offshore variable-speed turbine in deep water equipped with a permanent magnet synchronous generator using full-power two-level converter, converting the energy of a variable frequency source in injected energy into the electric network with constant frequency, through a high voltage DC transmission submarine cable. The mathematical model for the drive train is a concentrate two mass model which incorporates the dynamic for the structure and tower due to the need to emulate the effects of the moving surface. Controller strategy considered is a proportional integral one. Also, pulse width modulation using space vector modulation supplemented with sliding mode is used for trigger the transistor of the converter. Finally, a case study is presented to access the system performance. © 2014 IEEE.
- Simulation by discrete mass modeling of offshore wind turbine system with DC linkPublication . Seixas, Mafalda; Melicio, R.; Mendes, VictorThis paper presents an integrated model for an offshore wind turbine taking into consideration a contribution for the marine wave and wind speed with perturbations influences on the power quality of current injected into the electric grid. The paper deals with the simulation of one floating offshore wind turbine equipped with a permanent magnet synchronous generator, and a two-level converter connected to an onshore electric grid. The use of discrete mass modeling is accessed in order to reveal by computing the total harmonic distortion on how the perturbations of the captured energy are attenuated at the electric grid injection point. Two torque actions are considered for the three-mass modeling, the aerodynamic on the flexible part and on the rigid part of the blades. Also, a torque due to the influence of marine waves in deep water is considered. Proportional integral fractional-order control supports the control strategy. A comparison between the drive train models is presented.
- Fifth harmonic and sag impact on PMSG wind turbines with a balancing new strategy for capacitor voltagesPublication . Seixas, Mafalda; Melício, Rui; Mendes, VictorThis paper deals with the computing simulation of the impact on permanent magnet synchronous generator wind turbines due to fifth harmonic content and grid voltage decrease. Power converter topologies considered in the simulations are the two-level and the three-level ones. The three-level converters are limited by unbalance voltages in the DC-link capacitors. In order to lessen this limitation, a new control strategy for the selection of the output voltage vectors is proposed. Controller strategies considered in the simulation are respectively based on proportional integral and fractional-order controllers. Finally, a comparison between the results of the simulations with the two controller strategies is presented in order to show the main advantage of the proposed strategy. (C) 2014 Elsevier Ltd. All rights reserved.
- Offshore wind turbine simulation: multibody drive train. Bacl-to-back NPC (Neutral Point Clamped) converters: Fractional-order controlPublication . Seixas, Mafalda; Melício, Rui; Mendes, VictorThis paper is on offshore wind energy conversion systems installed on the deep water and equipped with back-to-back neutral point clamped full-power converter, permanent magnet synchronous generator with an AC link. The model for the drive train is a five-mass model which incorporates the dynamic of the structure and the tower in order to emulate the effect of the moving surface. A three-level converter and a four-level converter are the two options with a fractional-order control strategy considered to equip the conversion system. Simulation studies are carried out to assess the quality of the energy injected into the electric grid. Finally, conclusions are presented. (C) 2014 Elsevier Ltd. All rights reserved.
- Comparison of offshore and onshore wind systems with MPC five-level converter under 3Energy 4.0Publication . Seixas, Mafalda; Melício, R; Mendes, VictorThis paper is about offshore/onshore wind systems under energy 4.0. A consideration is taken to account for the action of the floating motion given by the stiffness torque acting on the drive-train. The drive-train incorporates the dynamics of the floating platform and tower, resulting from the motion of the surface due to the marine wave perturbation. The performance of the multiple point clamped five-level converter is considered mainly from electrical power perspective. The simulation considers a blade pitch control fault causing an instantaneous cutoff on the capture of the wind energy to unveil the impact on the systems performance. Particularly, the fault influence on the behavior of the voltages in the capacitor banks is mitigated by selection of the suitable vectors. The multiple point clamped five-level converter with the conveniently proposed control strategy is able to recover normal operation after fault clearing.
- HVDC power transmission simulation for offshore wind system with three-level converterPublication . Seixas, Mafalda; Melicio, Rui; Mendes, VictorAn integrated mathematical model for the simulation of an offshore wind system performance is presented in this paper. The mathematical model considers an offshore variable-speed turbine in deep water equipped with a permanent magnet synchronous generator using multiple point full-power clamped three-level converter, converting the energy of a variable frequency source in injected energy into the electric network with constant frequency, through a HVDC transmission submarine cable. The mathematical model for the drive train is a concentrate two mass model which incorporates the dynamic for the blades of the wind turbine, tower and generator due to the need to emulate the effects of the wind and the floating motion. Controller strategy considered is a proportional integral one. Also, pulse width modulation using space vector modulation supplemented with sliding mode is used for trigger the transistors of the converter. Finally, a case study is presented to access the system performance.
- Offshore wind energy system with DC transmission discrete mass: modeling and simulationPublication . Seixas, Mafalda; Melicio, Rui; Mendes, VictorThis article presents an integrated model for an offshore wind energy system taking into consideration a contribution for the marine wave and wind speed with perturbations influences on the power quality of current injected into the electric grid. The article deals with the simulation of one floating offshore wind turbine equipped with a permanent magnet synchronous generator and a two-level converter connected to an onshore electric grid. The use of discrete mass modeling is accessed in order to reveal by computing the total harmonic distortion on how the perturbations of the captured energy are attenuated at the electric grid injection point. Two torque actions are considered for the three-mass modeling, the aerodynamic on the flexible part and on the rigid part of the blades. Also, a torque due to the influence of marine waves in deep water is considered. Proportional integral fractional-order control supports the control strategy. A comparison between the drive train models is presented.
- Simulation of a rectifier malfunction on a offshore wind system with HVDC transmissionPublication . Seixas, Mafalda; Melicio, Rui; Mendes, Victor; Couto, CarlosA new integrated mathematical model for the simulation of an offshore wind system having a rectifier input voltage malfunction at one phase is presented in this paper. The mathematical model considers an offshore variable-speed wind turbine on a floating platform, equipped with a permanent magnet synchronous generator using full-power three-level converter to inject energy into the electric network, through a high voltage direct current transmission submarine cable. The model for the drive train is a discrete three mass, incorporating the dynamic of the moving surface. A case study is presented to access conclusion about the malfunction.
- Simulation of OWES with five-level converter linked to the grid: harmonic assessmentPublication . Seixas, Mafalda; Melicio, Rui; Mendes, Victor; Couto, CarlosThis paper deals with a computing simulation for an offshore wind energy system taking into account the influence of the marine waves action throughout the floating platform. The wind energy system has a variable-speed turbine equipped with a permanent magnet synchronous generator and a full-power five-level converter, injecting energy into the electric grid through a high voltage alternate current link. A reduction on the unbalance of the voltage in the DC-link capacitors of the five-level converter is proposed by a strategic selection of the output voltage vectors. The model for the drive train of the wind energy system is a two mass model, including the dynamics of the floating platform. A case study is presented and the assessment of the quality of the energy injected into the electric grid is discussed.
- Simulation of offshore wind system with two levels converters: HVDC power transmissionPublication . Seixas, Mafalda; Melício, Rui; Mendes, Victor; Pousinho, Hugo Miguel InácioA new integrated mathematical model for the simulation of offshore wind energy conversion system performance is presented in this paper. The mathematical model considers an offshore variable-speed turbine in deep water equipped with a permanent magnet synchronous generator using full-power two-level converter, converting the energy of a variable frequency source in injected energy into the electric network with constant frequency, through a high voltage DC transmission submarine cable. The mathematical model for the drive train is a concentrate two mass model which incorporates the dynamic for the structure and tower due to the need to emulate the effects of the moving surface. Controller strategy considered is a proportional integral one. Also, pulse width modulation using space vector modulation supplemented with sliding mode is used for trigger the transistor of the converter. Finally, a case study is presented to access the system performance. © 2014 IEEE.