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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Multi-input multi-output proportional integral derivative controller tuning based on improved particle swarm optimization

Nkwanyana, Thamsanqa Bongani 07 1900 (has links)
The PID controller is regarded as a dependable and reliable controller for process industry systems. Many researchers have devoted time and attention to PID controller tuning and they all agree that PID controllers are very important for control systems. A PID equation is very sensitive; its parameters must always be varied following the specific application to increase performance, such as by increasing the system’s responsiveness. PID controllers still have many problems despite their importance for control systems in industries. The problem of big overshoot on the conventional gain tuning is one of the serious problems. Researchers use the PSO algorithm to try and overcome those problems. The tuning of the MIMO PID controller based on the PSO algorithm shows many disadvantages such as high-quality control with a short settle time, steady-state error, and periodical step response. The traditional PSO algorithm is very sensitive and it sometimes affects the quality of good PID controller tuning. This research has proposed a new equation for improving the PSO algorithm. The proposed algorithm is the combination of linearly decreasing inertia weight and chaotic inertia weight, after which a control factor was introduced as an exponential factor. This was very useful for simulations as it is adjustable. The Matlab simulation results of the experiments show that the simulations as it is adjustable. The Matlab simulation results of the experiments show that the new proposed equation converges faster and it gives the best fitness compared to linear inertia weight and oscillating inertia weight and other old equations. The MIMO PID controller system that consists of four plants was tuned based on the new proposed equation for the PSO algorithm (LCPSO). The optimized results show the best rise time, settling time, time delays, and steady-state compared to the systems that are tuned using the old equations. The exploration was directed at considering the impact of using the PSO calculation as an instrument for MIMO PID tuning. The results obtained in the examination reveal that the PSO tuning output improved reactions and can be applied to various system models in the measure control industry. The results for the MIMO PID controller tuned using PSO were assessed using integral square error (ISE), integral absolute error (IAE), and the integral of time expanded by absolute error (ITAE). The five well-known benchmark functions were also used to endorse the feasibility of the improved PSO and excellent results in terms of convergence and best fitness were attained. / Electrical and Mining Engineering / M. Tech. (Electrical Engineering)
72

Conversor SEPIC modificado com acoplamento magnético série e célula multiplicadora de tensão / Modified SEPIC converter with serial magnetic coupling and voltage multiplier cell

Kravetz, Fábio Inocêncio 29 March 2018 (has links)
As fontes renováveis de energia, em especial a energia solar fotovoltaica vem ganhando espaço nos últimos anos devido ao avanço da tecnologia, redução dos custos e redução das fontes não-renováveis. Os painéis fotovoltaicos isoladamente ou para pequenas aplicações geram uma baixa tensão de saída e a adequação dos níveis de tensão fornecidos em sua saída aos requeridos pela concessionária de energia elétrica é um desafio. Neste trabalho é apresentada uma nova estrutura modificada da topologia do conversor SEPIC que usa as técnicas de acoplamento magnético série e células multiplicadoras de tensão em conjunto, afim de obter um elevado ganho de tensão, visando a aplicação em fontes renováveis de energia. Optou-se pela solução não isolada, pois esta apresenta diversas vantagens em relação a solução isolada, como: menor peso, volume, custo e maior eficiência energética devido a menores perdas de potência nos indutores acoplados. Também, a utilização da indutância de dispersão, que é um parâmetro intrínseco de um acoplamento magnético, permite a operação com comutação suave ZCS (ZCS, do inglês Zero Current-Switching) no interruptor, aumentando a eficiência da estrutura com a redução das perdas por comutação. No decorrer do trabalho são realizadas as análises das etapas de operação de diversos conversores a partir do conversor SEPIC modificado, evolui-se pela adição de técnicas elevadoras de tensão até a estrutura proposta neste trabalho. Por fim, é realizado o controle em malha fechada utilizando um controlador PID analógico que fornece uma resposta rápida e consequente correção a possíveis mudanças na variável controlada. Os resultados teóricos e experimentais do conversor proposto são descritos neste trabalho para validar as análises desenvolvidas e demonstrar a eficiência da estrutura. O protótipo é desenvolvido para uma aplicação com potência nominal de 200 W, tensão nominal de saída igual a 450 V e uma tensão de entrada variando entre 20 V e 40 V. O rendimento obtido para o conversor proposto operando na frequência de 35 kHz na potência nominal é de 91,28% e eficiência igual a 89,04% para a potência nominal de 200 W na frequência de 90 kHz. / The renewable energy resources, in special the photovoltaic energy has been achieve more space in last years due to technology advances, cost reduction and decrease of the non-renewable energy sources. The photovoltaic panels in isolation or to small applications generate a low output voltage and to comply with of voltage levels provided in panel’s output to those required by electric power concessionaire is a challenge. In this work is presented a new structure modified of the SEPIC converter topology who uses the coupling magnetic series and voltage multiplier cell techniques together, in order to obtain a high voltage gain aiming at application in renewable energy resources. It was has been choosen non-isolated solution, because this present several advantages in relation to the isolated solution, such as: lower weight, volume, cost and high energy efficiency due to smaller power losses in the coupled inductors. The use leakage inductance, who is an intrinsic parameter of the a magnetic coupling, allows soft-switching operation ZCS in switch, increasing the structure’s efficiency with reduction of switching losses. During the work are perform the analysis of the operation steps of several converters as of the modified SEPIC converter and evolves by addition high voltage techniques until the structure proposed in this work. Finally, is performed the closed loop control using the analog PID controller who provides a fast response and consequent correction to possible changes in the controlled variable. The theoretical and experimental results of the proposed converter are described in this work to validate the developed analysis and demonstrate the structure’s efficiency. The prototype is developed to a application with nominal power of 200 W, nominal output voltage equal 450 V and an input voltage varying between 20 V and 40 V. The efficiency obtained to proposed converter operating in frequency of the 35 kHz in nominal power is 91,28% and efficiency equal 89,04% to nominal power in frequency of the 90 kHz.
73

Eficiência energética por meio de um controlador PI autossintonizado por lógica fuzzy em sistema de distribuição de água de um setor da grande Curitiba / Energy efficiency by a PI controller self-tuned by fuzzy logic in a water distribution system of a sector of the great Curitiba

Pena, Jailson Silvério 23 March 2018 (has links)
Esta dissertação apresenta uma aplicação de inteligência artificial, a lógica fuzzy, estruturada como um controlador fuzzy, para a sintonia dos ganhos Kp e Ki de um controlador PI. Este último, configurado num conversor de frequência para a operação de um conjunto motor-bomba do sistema de abastecimento de água potável na região denominada de Recalque Mercês (RMER), na cidade de Curitiba, compreendendo 4 bairros com 140 km de tubulação e mais de 13 mil ligações a clientes. Hoje, o sistema funciona com controle PI tradicional de ganhos fixos, variando a velocidade do conjunto motorbomba, controlados por um sensor de pressão à jusante do bombeamento. Contudo, a variação de consumo de água potável fornecida é muito grande durante o período de um dia, sendo máxima no entardecer e mínima durante a madrugada, e com características sazonais, o consumo aumenta com o calor e diminui no frio, o que faz esse tipo de controle fixo ser ineficiente em determinados momentos. A proposta é adotar o controle fuzzy para alterar os coeficientes do controlador PI ao longo do dia, de forma autônoma, de acordo com o consumo instantâneo e assim, alcançar uma melhor eficiência energética do sistema, prezando pela qualidade do serviço prestado à população. Isto é, garantindo a vazão e a pressão de água para o consumidor. Por meio do MatLab®, mais precisamente os toolbox’s de simulação, Simulink® e SimScape®, foram criados dois modelos, um com o controle atual e o outro com a proposta inteligente, de uma abreviação da rede e do sistema de bombeamento da elevatória existente, a diminuição de 4 conjuntos motor-bomba para apenas 1 (um) e num trajeto único, perfazendo 5,4 km de distância, até o local denominado de ponto crítico, onde é mais longe, alto e difícil de se manter a pressão no patamar de 10 m.c.a. (1 bar), por norma. O controlador fuzzy desenvolvido possui 2 entradas, o nível do reservatório e a pressão à jusante do conjunto motor-bomba, e 2 saídas, os ganhos proporcional e integral para o PI. Com a estrutura baseado em regras, foram criadas 123 regras de inferência para que o sistema obtenha um desempenho favorável. As simulações foram realizadas com a referência de dados – 3 meses de histórico – de medições do reservatório e do sensor de pressão que é a realimentação do controle PI existente. Assim, a eficiência energética de 6,15% ao mês, em termos de energia elétrica consumida, foi conseguida, comparando com o modelo de controle tradicional. / This dissertation presents an application of artificial intelligence, the fuzzy logic, structured as a fuzzy controller, for the tuning of the Kp and Ki gains of a PI controller. The latter, configured in a frequency converter for the operation of a motor-pump assembly of the drinking water supply system in the region called Recalque Mercês (RMER), in the city of Curitiba, comprising 4 districts with 140 km of pipeline and more than 13 thousand connections to customers. Today, the system operates with PI traditional control with fixed gains, varying the speed of the motor-pump assembly, controlled by a pressure sensor downstream to the pumping. However, the variation in the consumption of potable water supplied is very large during the period of one day, being maximum at dusk and minimum during the dawn, and with seasonal characteristics, consumption increases with heat and decreases in the cold, which makes static control inefficient at certain times. The proposal is to adopt the fuzzy control to change the coefficients of the PI controller throughout the day, autonomously, according to the instantaneous consumption and thus achieve a better energy efficiency of the system, appreciating the quality of service provided to the population. That is, ensuring the flow and pressure of water to the consumer. Through MatLab®, simulation tools, Simulink® and SimScape®, two models were created, one with the current control and the other with the intelligent proposal. An abbreviation of the network and the existing pumping system of the lift, the reduction of 4 engine-pump assemblies to only 1 (one) and a single path, making 5.4 km distance, to the socalled critical point location, where it is further, higher and more difficult to keep the pressure at the 10 mwg (1 bar), as a rule. The developed fuzzy controller has 2 inputs, the reservoir level and the downstream pressure of the motor-pump assembly, and 2 outputs, proportional and integral gains for the PI. With the rulesbased framework, 123 inference rules were created for the system to perform favorably. The simulations were carried out with the reference of data – 3 months of historical – of measurements of the reservoir and pressure sensor that is the feedback of the existing PI control. Thus, the energy efficiency of 6.15% per month, in terms of electric power consumed, was achieved, compared to the traditional control model.
74

Avaliação de desempenho de controladores preditivos multivariáveis

Santos, Rodrigo Ribeiro 11 November 2013 (has links)
In advanced process control, the Model Predictive Control (MPC) may be considered the most important innovation in recent years and the standard tool for industrial applications due to the fact that it keeps the plant operating in the constraints more profitable. However, like every control algorithm, the MPC after some time in operation rarely works as originally designed. Thus, to preserve the benefits of MPC systems for a long period of time, their performance needs to be monitored and evaluated during the operation. This task require the presence of reliable and effective tools to detect when the controller performance is below of the desirable, to define the need, or not, of recommissioning the system. Thus, the objective of this work is development of techniques for monitoring and evaluating the performance of multivariable predictive controllers, being developed two new tools: LQG benchmark Modified and IHMC benchmark. The results obtained from numerical simulations were satisfactory and consistent with the technical literature applied in the developments of the evaluators, which were used in the monitoring of the control system MPC of the oil-water-gas three-phase separation process, offering an appropriate solution and providing subsidies for implementations in real industrial systems. / Em controle avançado de processos, o controlador preditivo ou MPC (Model Predictive Control) pode ser considerado como a mais importante inovação dos últimos anos e a ferramenta padrão para aplicações industriais, devido ao fato do MPC manter a planta operando dentro das suas restrições de forma mais lucrativa. Entretanto, como todo algoritmo de controle, o MPC depois de algum tempo em operação dificilmente funciona como quando fora inicialmente projetado. Desta forma, com o objetivo de manter os benefícios dos sistemas MPC por um longo período de tempo, seu desempenho precisa ser monitorado e avaliado durante a operação. Esta tarefa requer a presença de ferramentas efetivas e confiáveis para detectar quando o desempenho do controlador estiver abaixo do desejável, para definir a necessidade, ou não, de um recomissionamento do sistema. Destarte, aborda-se neste trabalho o desenvolvimento de técnicas para monitoramento e avaliação de desempenho de controladores preditivos multivariáveis, sendo desenvolvidas duas novas ferramentas: LQG benchmark Modificado e IHMC benchmark. Os resultados obtidos a partir de simulações numéricas foram satisfatórios e coerentes com a literatura técnica aplicada no desenvolvimento dos avaliadores, os quais foram utilizados no monitoramento do sistema de controle MPC do processo de separação trifásica água-óleo-gás, oferecendo assim uma solução apropriada e fornecendo subsídios para implementações em sistemas industrias reais.
75

Evaluation of performance of an air handling unit using wireless monitoring system and modeling

Khatib, Akram Ghassan January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Heating, ventilation, and air conditioning (HVAC) is the technology responsible to maintain temperature levels and air quality in buildings to certain standards. In a commercial setting, HVAC systems accounted for more than 50% of the total energy cost of the building in 2013 [13]. New control methods are always being worked on to improve the effectiveness and efficiency of the system. These control systems include model predictive control (MPC), evolutionary algorithm (EA), evolutionary programming (EP), and proportional-integral-derivative (PID) controllers. Such control tools are used on new HVAC system to ensure the ultimate efficiency and ensure the comfort of occupants. However, there is a need for a system that can monitor the energy performance of the HVAC system and ensure that it is operating in its optimal operation and controlled as expected. In this thesis, an air handling unit (AHU) of an HVAC system was modeled to analyze its performance using real data collected from an operating AHU using a wireless monitoring system. The purpose was to monitor the AHU's performance, analyze its key parameters to identify flaws, and evaluate the energy waste. This system will provide the maintenance personnel to key information to them to act for increasing energy efficiency. The mechanical model was experimentally validated first. Them a baseline operating condition was established. Finally, the system under extreme weather conditions was evaluated. The AHU's subsystem performance, the energy consumption and the potential wastes were monitored and quantified. The developed system was able to constantly monitor the system and report to the maintenance personnel the information they need. I can be used to identify energy savings opportunities due to controls malfunction. Implementation of this system will provide the system's key performance indicators, offer feedback for adjustment of control strategies, and identify the potential savings. To further verify the capabilities of the model, a case study was performed on an air handling unit on campus for a three month monitoring period. According to the mechanical model, a total of 63,455 kWh can be potentially saved on the unit by adjusting controls. In addition the mechanical model was able to identify other energy savings opportunities due to set point changes that may result in a total of 77,141 kWh.

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