| 1. |
- Archetti, Joao A. G., et al.
(author)
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Hardware-in-the-Loop Volt-Watt and Volt-VAr Control for Distribution Systems with High Penetration of Renewables
- 2023
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In: Journal of Control Automation and Electrical Systems. - : Springer Nature. - 2195-3880 .- 2195-3899. ; 34:1, s. 177-188
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Journal article (peer-reviewed)abstract
- This work aims to validate in control hardware in the loop (CHIL) simulations new voltage profile control strategies in distribution systems with different levels of photovoltaic penetration. The proposed control is implemented through intelligent inverters with control functions that act through voltage sensitivity. The Volt-VAr (V-V) and Volt-Watt (V-W) functions act in the local voltage control being implemented in a complementary way. The simulations are performed in real time, using the real-time digital simulator. Residential load profiles, solar irradiance and temperature curves are discretized hourly over a daily period, with the intention of making the emulation more realistic. Voltage source converters were implemented in RSCAD software. The contribution of this article points to the performance of the Volt-Watt (V-W) control function in single-stage inverters, which allows the maximum generation of instantaneous active power, acting directly on the maximum power point tracking algorithm, this strategy being validated by the CHIL simulation. The results show that the Volt-VAr and Volt-Watt control functions, acting at different levels of photovoltaic penetration, were effective in preventing the voltage profiles from violating the critical level imposed by the regulatory standard. Leading to the conclusion that its implementation directly in photovoltaic inverters entails a low cost and a complementary solution for the new challenges of electrical systems.
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| 2. |
- de Souza, Leonardo C. O., et al.
(author)
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Performance Analysis of a Silo-SlideGate-Feeder System to Regulate the Ore Flow by DEM Simulation
- 2022
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In: Journal of Control, Automation and Electrical Systems. - : Springer. - 2195-3880 .- 2195-3899. ; 33:4, s. 1310-1318
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Journal article (peer-reviewed)abstract
- Severe variability of fresh feed ore flowrate in a crushing circuit may cause some operational damages. Related issues include conveyor belt and sieves overload, interlocked crushers, early equipment wear, and silos overflow. Usually, the speed of feeders is used to control the ore output from silos; however, it is ineffective in regulating the height of material carried by the feeder. The introduction of a slide gate in the primary silo of the crushing circuit is an alternative to increase the degree of freedom for controlling the fresh ore flowrate. This paper presents a numerical simulation using a discrete element method (DEM) applied in a silo-gate-feeder system. The simulated model is based on parameters from a Vale’s iron ore beneficiation plant located in Serra Leste Mine, city of Curionópolis, Brazil. The simulation was carried out using the software Siemens Star CCM+ ®. Three scenarios were evaluated, such as changes in the slide gate aperture. The results show that regulating the feeder speed simultaneously with the gate aperture provides a novel control strategy to reduce variability in fresh ore flowrate. The best simulation result reduced in about 11% the variability flowrate compared with the case with no slide gate.
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| 3. |
- Ljung, Lennart, 1946-
(author)
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Some Classical and Some New Ideas for Identification of Linear Systems
- 2013
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In: Journal of Control, Automation and Electrical Systems. - : Springer. - 2195-3880 .- 2195-3899. ; 24:1-2, s. 3-10
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Journal article (peer-reviewed)abstract
- This paper gives an overview of the identificationof linear systems. It covers the classical approach ofparametric methods by means of maximum likelihood andpredicion error methods, as well all classical non-parametricmethods through spectral analysis. It also covers very recenttechniques dealing with convex formulations by regularizationof FIR and ARX models, as well as new alternatives tospectral analysis, through local linear models. An example of identification of aircraft dynamics illustrates the approaches.
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| 4. |
- Silva Júnior, Dalmo C., et al.
(author)
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Control of Smart Inverters with Automated Decisions in Microgrid
- 2023
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In: Journal of Control, Automation and Electrical Systems. - : Springer. - 2195-3880 .- 2195-3899. ; 34, s. 1028-1042
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Journal article (peer-reviewed)abstract
- In this article, a smart inverter model that executes ancillary services with automated decisions is presented, such as powersharing and voltage and frequency stabilization, compensation of unbalance voltage, mitigation of harmonic content, and thebalance of generation and demand. The droop control was utilized for power-sharing between the distributed generations; themitigation of negative-sequence voltage is used for unbalanced voltage compensation, and finally, a feed-forward current isadopted for harmonic compensation. Therefore, the smart inverter was controlled through a supervisory system, identifyingwhich ancillary function to activate at certain times. Results show the successful operation of the system and can be used asvalidation of the proposed control strategies, including the automated decisions in the microgrid
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| 5. |
- Stotsky, Alexander, 1960
(author)
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Frequency Regulation in Smart Microgrids Based on Load Estimation
- 2018
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In: Journal of Control, Automation and Electrical Systems. - : Springer Science and Business Media LLC. - 2195-3880 .- 2195-3899. ; 29:4, s. 525-533
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Journal article (peer-reviewed)abstract
- The desired frequency is maintained in Smart Microgrid (SMG) when the generated power matches the grid load. Variability of wind power and fluctuations of the load are the main obstacles for performance improvement of frequency regulation in SMG. Active Power Control (APC) services provided by wind power generators is one of the main sources for performance improvement in frequency regulation. New coordinated APC architecture, which involves simultaneous speed and pitch control actions delivers desired power to the grid despite significant variations of the wind power. A tool-kit with discrete-time input estimation algorithms, which estimate input quantity using output measurements is presented. Unmeasurable load fluctuations are estimated with input estimation method using measurements of grid frequency deviation. Desired power for APC is driven by estimated and a priori known loads. This observer-based control method reduces the risk of overshoots and oscillations in frequency regulation loop compared to PID controllers driven directly by the frequency deviation. The stability of the closed loop frequency control system is proved, and simulation results show that observer-based control architecture provides significant improvement of the frequency regulation in SMG.
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| 6. |
- Caldas, Kenny A. Q., et al.
(author)
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Autonomous Driving of Trucks in Off-Road Environment
- 2023
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In: JOURNAL OF CONTROL AUTOMATION AND ELECTRICAL SYSTEMS. - : Springer. - 2195-3880. ; 34:6, s. 1179-1193
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Journal article (peer-reviewed)abstract
- Off-road driving operations can be a challenging environment for human conductors as they are subject to accidents, repetitive and tedious tasks, strong vibrations, which may affect their health in the long term. Therefore, they can benefit from a successful implementation of autonomous vehicle technology, improving safety, reducing labor costs and fuel consumption, and increasing operational efficiency. The main contribution of this paper is the experimental validation of a path tracking control strategy, composed of longitudinal and lateral controllers, on an off-road scenario with a fully loaded heavy-duty truck. The longitudinal control strategy relies on a nonlinear model predictive controller, which considers the path geometry and simplified vehicle dynamics to compute a smooth and comfortable input velocity, without violating the imposed constraints. The lateral controller is based on a robust linear quadratic regulator, which considers a vehicle model subject to parametric uncertainties to minimize its lateral displacement and heading error, as well as ensure stability. Experiments were carried out using a fully loaded vehicle on unpaved roads in an open-pit mine. The truck followed the reference path within the imposed constraints, showing robustness and driving smoothness.
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