A new discrete-time Robust Adaptive Predictive Control-based RMRAC applied to grid connected converters with LCL Filter / Um novo controlador preditivo robusto adaptativo baseado em RMRAC em tempo discreto aplicado a conversores conectados à rede com filtro LCL

In this work, is developed a new discrete-time robust adaptive predictive control based on combining the adaptive structure of a Model Reference Adaptive Controller  (MRAC),  to adjust gains online, with the control law One Sample Ahead Preview (OSAP), a particular case of deadbeat controller, for the current loop of a grid-connected voltage-source converter, also,  this control not need resonant controllers to reject exogenous disturbances. A case application is presented, the grid-side currents control of a three-phase full-bridge static converter connected to the electrical grid by LCL filter. Simulation results are presented to show the performance of the proposed controller in a grid connected system

UFSM-CS vai às escolas 2017

The Federal University of Santa Maria - Cachoeira do Sul Campus began its activities in 2014 with five graduate courses: Architecture and Urbanism; Agricultural Engineering; Electrical Engineering; Mechanical Engineering; and Transport and Logistics Engineering. The need of technological professionals to meet regional and national demand was considered at the UFSM-Cachoeira do Sul (UFSM-CS) conception. However,  the population of Cachoeira do Sul and nearby cities do not know about the courses offered by UFSM-CS. In order to alleviate this problem, the program UFSM-CS goes to Schools is in operation, whose main objective is to present the courses offered by UFSM-CS to high school students in public and private schools. This project has been developed in two stages: in the first stage, a questionnaire about the previous knowledge of the school community about the UFSM campus is applied. In the second stage, a cycle of lectures in public and private schools to show the undergraduate courses in the Cachoeira do Sul campus is done and then a new questionnaire is applied to check if the lecture cycle has indeed encouraged these students to enter UFMS-CS and/or another institution.  A statistical analysis of the data obtained through questionnaires is presented to support extension projects with the schools of Cachoeira do Sul and region. Results show that 80% of students intend to enter a higher education institution and 70% do not know which courses are provided by UFSM-CS. After the presentation of the seminars, 92% of the students told the seminars were enlightening.O Campus da Universidade Federal de Santa Maria em Cachoeira do Sul iniciou suas atividades em 2014 com cinco cursos de graduação: Arquitetura e Urbanismo; Engenharia Agrícola; Engenharia Elétrica; Engenharia Mecânica; e Engenharia de Transportes e Logística. Na concepção do campus da UFSM em Cachoeira do Sul (UFSM-CS), considerou-se a necessidade de profissionais na área tecnológica para atender a demanda regional e nacional. No entanto, é notável que a população de Cachoeira do Sul e região ainda está mal informada sobre os cursos oferecidos pela UFSM-CS. No intuito de amenizar esse problema, está em andamento o Programa UFSM-CS vai às Escolas que tem como principal objetivo apresentar, aos alunos do ensino médio de escolas públicas e particulares, os cursos ofertados pela UFSM-CS. Esse projeto está sendo desenvolvido em duas etapas: na primeira etapa, é aplicado um questionário sobre os conhecimentos prévios da comunidade escolar cachoeirense sobre o campus da UFSM. Na segunda etapa, é realizado um ciclo de palestras nas escolas públicas e particulares para divulgar os cursos de graduação do campus de Cachoeira do Sul e é aplicado outro questionário para verificar se o ciclo de palestrar despertou o interesse desses alunos a ingressarem no ensino superior na UFMS-CS e/ou em outra instituição. Neste trabalho apresentaremos uma análise estatística dos dados obtidos através dos questionários para servir de suporte a futuros projetos de extensão com as escolas de Cachoeira do Sul e região. Resultados mostram que cerca de 80% dos alunos pretendem ingressar em uma instituição de ensino superior e que 70% não sabem quais cursos são oferecidos pela UFSM-CS. Após a apresentação dos seminários, 92% dos alunos acharam o mesmo esclarecedor

Performance comparison of discrete-time robust adaptive controllers for grid-tied power converters under unbalanced grids

Renewable energy generation systems largely use grid-tied power converters with LCL filters. A well-known issue in this kind of system is the resonance of the LCL filter, whose frequency is straightforwardly affected by grid condition. Variations on grid impedance tends to make the controller performance poor and until turn the closed-loop unstable. Therefore, some controllers are designed for specific operation ranges to ensure performance and global stability. However, a deep study of Model Reference Adaptive-based Controllers for this kind of issue was not conducted yet. The aim of this paper is to fit this research gap. Thus, this paper presents a performance comparison of feasible discrete-time robust adaptive controllers, based on reduced order reference model, for grid-tied power converters with LCL filter under unbalanced grid conditions, providing an assessment of the benefits and drawbacks of each considered control strategy. The evaluated control laws are: Robust Model Reference Adaptive Controller, Robust Model Reference-based Adaptive Super-Twisting Sliding Mode Controller, Robust Adaptive One Sample Ahead Preview Controller, and Robust Adaptive Proportional-Integral Controller. Through performance comparison, it can be defined what controller is more adequate in face of grid condition, taking into consideration grid-injected currents quality and design complexity of controller. Experimental results of grid-injected current control of a grid-tied 5.8 kW Voltage-Source Inverter with LCL filter considering relevant grid voltage unbalance are presented to corroborate the controllers’ performance and discuss their reference tracking response, robustness to the parametric variation, exogenous disturbance rejection, parameters adaptability, and global stability. In evaluated scenarios, Robust Adaptive Proportional-Integral controller presented slower regulation dynamics between compared adaptive structures, but reduced tracking error, as well as lower total harmonics distortion, while Robust Model Reference-based Adaptive Super-Twisting Sliding Mode Controller has the smaller overshoot in the initial transient regime, as well as the shorter transient regime