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Prof. Alejandro Garces
Universidad Tecnológica de Pereira

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0 Convex Optimization
0 Dynamical Systems
0 Energy Storage
0 microgrids
0 power systems optimization and control

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microgrids
Energy Storage
Convex Optimization
Dynamical Systems

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Journal article
Published: 30 June 2021 in IEEE Latin America Transactions
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This paper addresses the problem of parametric estimation in solar cells considering manufacturer datasheet information regarding open-circuit, short-circuit, and maximum power points from the point of view of mathematical optimization. To represent this problem a single-objective function is formulated associated with the minimization of the mean square error of the single-diode model evaluated in the operational points reported by the manufacturer. The solution of this nonlinear non-convex optimization model is addressed with a metaheuristic optimization technique known in specialized literature as a vortex search algorithm (VSA). This metaheuristic optimization method works with Gaussian distribution functions and variable radius to explore and exploit the solution space by generating hyperspheres that move through the solution space as a function of the best current solution. The VSA is implemented in MATLAB environment by using commercial photovoltaic module information, where numerical results demonstrate the efficiency of this optimization method with objective functions lower than 1times10-25 and processing times around 6.13s.

ACS Style

Oscar Danilo Montoya; Walter Julian Gil-Gonzalez; Jesus Maria Lopez-Lezama. Vortex Search Algorithm Applied to the Parametric Estimation in PV Cells Considering Manufacturer Datasheet Information. IEEE Latin America Transactions 2021, 19, 1581 -1589.

AMA Style

Oscar Danilo Montoya, Walter Julian Gil-Gonzalez, Jesus Maria Lopez-Lezama. Vortex Search Algorithm Applied to the Parametric Estimation in PV Cells Considering Manufacturer Datasheet Information. IEEE Latin America Transactions. 2021; 19 (9):1581-1589.

Chicago/Turabian Style

Oscar Danilo Montoya; Walter Julian Gil-Gonzalez; Jesus Maria Lopez-Lezama. 2021. "Vortex Search Algorithm Applied to the Parametric Estimation in PV Cells Considering Manufacturer Datasheet Information." IEEE Latin America Transactions 19, no. 9: 1581-1589.

Research article electrical engineering
Published: 23 June 2021 in Arabian Journal for Science and Engineering
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In this study, we present a master–slave methodology to solve the problem of optimal power dispatch in a direct current (DC) microgrid. In the master stage, the Antlion Optimization (ALO) method solves the problem of power dispatch by the Distributed Generators (DGs); in the slave stage, a numerical method based on successive approximations (SA) evaluates the load flows required by the potential solutions proposed by the ALO technique. The objective functions in this paper are the minimization of energy production costs and the reduction of \(\hbox {CO}_2\) emissions produced by the diesel generators in the microgrid. To favor energy efficiency and have a lower negative impact on the environment, the DC microgrids under study here include three DGs (one diesel generator and two generators based on renewable energy sources, i.e., solar energy and wind power) and a slack bus connected to a public electrical grid. The effectiveness of the proposed ALO–SA methodology was tested in the 21- and 69-bus test systems. We used three other optimization techniques to compare methods in the master stage: particle swarm optimization, continuous genetic algorithm, and black hole optimization. Additionally, we combined SA with every method to solve the load flow problem in the slave stage. The results show that, among the methods analyzed in this study, the proposed ALO–AS methodology achieves the best performance in terms of lower energy production costs, less \(\hbox {CO}_2\) emissions, and shorter computational processing times. All the simulations were performed in MATLAB.

ACS Style

J. A. Ocampo-Toro; O. D. Garzon-Rivera; L. F. Grisales-Noreña; O. D. Montoya-Giraldo; W. Gil-González. Optimal Power Dispatch in Direct Current Networks to Reduce Energy Production Costs and $$\hbox {CO}_2$$ Emissions Using the Antlion Optimization Algorithm. Arabian Journal for Science and Engineering 2021, 1 -12.

AMA Style

J. A. Ocampo-Toro, O. D. Garzon-Rivera, L. F. Grisales-Noreña, O. D. Montoya-Giraldo, W. Gil-González. Optimal Power Dispatch in Direct Current Networks to Reduce Energy Production Costs and $$\hbox {CO}_2$$ Emissions Using the Antlion Optimization Algorithm. Arabian Journal for Science and Engineering. 2021; ():1-12.

Chicago/Turabian Style

J. A. Ocampo-Toro; O. D. Garzon-Rivera; L. F. Grisales-Noreña; O. D. Montoya-Giraldo; W. Gil-González. 2021. "Optimal Power Dispatch in Direct Current Networks to Reduce Energy Production Costs and $$\hbox {CO}_2$$ Emissions Using the Antlion Optimization Algorithm." Arabian Journal for Science and Engineering , no. : 1-12.

Journal article
Published: 20 June 2021 in Electric Power Systems Research
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This article presents an optimization model for tertiary control in three-phase unbalanced microgrids. This model considers 24h operation and includes renewable energy sources, energy storage devices, and grid code limitations. Power flow equations are simplified using a recently developed approximation based on Wirtinger’s calculus. The proposed model is evaluated both theoretically and practically. From the theoretical point of view, the model is suitable for tertiary control since it is convex; hence, global optimum, uniqueness of the solution, and convergence of the interior point method are guaranteed. From the practical point of view, the model is simple enough to be implemented in a small single-board computer with low time calculation. The latter is evaluated by implementing the model in a Raspberry-Pi board with the CIGRE low voltage benchmark; the model is also evaluated in the IEEE 123-nodes test system for power distribution networks.

ACS Style

Diego-Alejandro Ramirez; Alejandro Garcés; Juan-José Mora-Flórez. A Convex Approximation for the Tertiary Control of Unbalanced Microgrids. Electric Power Systems Research 2021, 199, 107423 .

AMA Style

Diego-Alejandro Ramirez, Alejandro Garcés, Juan-José Mora-Flórez. A Convex Approximation for the Tertiary Control of Unbalanced Microgrids. Electric Power Systems Research. 2021; 199 ():107423.

Chicago/Turabian Style

Diego-Alejandro Ramirez; Alejandro Garcés; Juan-José Mora-Flórez. 2021. "A Convex Approximation for the Tertiary Control of Unbalanced Microgrids." Electric Power Systems Research 199, no. : 107423.

Journal article
Published: 26 May 2021 in Applied Sciences
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Transportation electrification has demonstrated a significant position on power utilities and logistic companies, in terms of assets operation and management. Under this context, this paper presents the problem of seeking feasible and good quality routes for electric light commercial vehicles considering battery capacity and charging station siting on the power distribution system. Different transportation patterns for goods delivery are included, such as the capacitated vehicle routing problem and the shortest path problem for the last mile delivery. To solve the problem framed within a mixed integer linear mathematical model, the GAMS software is used and validated on a test instance conformed by a 19-customer transportation network, spatially combined with the IEEE 34 nodes power distribution system. The sensitivity analysis, performed during the computational experiments, show the behavior of the variables involved in the logistics operation, i.e., routing cost for each transport pattern. The trade-off between the battery capacity, the cost of the charging station installation, and energy losses on the power distribution system is also shown, including the energy consumption cost created by the charging operation.

ACS Style

Andrés Arias-Londoño; Walter Gil-González; Oscar Montoya. A Linearized Approach for the Electric Light Commercial Vehicle Routing Problem Combined with Charging Station Siting and Power Distribution Network Assessment. Applied Sciences 2021, 11, 4870 .

AMA Style

Andrés Arias-Londoño, Walter Gil-González, Oscar Montoya. A Linearized Approach for the Electric Light Commercial Vehicle Routing Problem Combined with Charging Station Siting and Power Distribution Network Assessment. Applied Sciences. 2021; 11 (11):4870.

Chicago/Turabian Style

Andrés Arias-Londoño; Walter Gil-González; Oscar Montoya. 2021. "A Linearized Approach for the Electric Light Commercial Vehicle Routing Problem Combined with Charging Station Siting and Power Distribution Network Assessment." Applied Sciences 11, no. 11: 4870.

Journal article
Published: 14 May 2021 in IEEE Access
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Short-Term Hydrothermal Scheduling (STHS) is a classic problem in power system operation where the aim is to decide the dispatch of both thermal and hydroelectric units. This problem is complex due to its non-linear non-convex nature, and the requirements for fast solving for daily operation. Technologies such as wind and solar generation introduce stochastic behaviors, which have to be considered within the mathematical model. Although the problem is frequently solved by traditional and heuristic techniques, this paper proposes a new formulation based on convex approximations, and in particular, Second-Order Cone optimization, which addresses the nonlinear relation among water discharge, reservoir volume, and hydropower generation in a rigorous mathematical approach. Moreover, the impact of wind and solar generation on the power system is analyzed, modeling their stochastic behavior in a robust way by using chance-box constraints. Numerical results demonstrate that the Second-Order Cone approximation is precise and faster than techniques proposed recently and that the chance-box constraint approach guarantees a robust solution.

ACS Style

Juan Camilo Castano; Alejandro Garces; Olav B. Fosso. Short-Term Hydrothermal Scheduling With Solar and Wind Farms Using Second-Order Cone Optimization With Chance-Box Constraints. IEEE Access 2021, 9, 74095 -74109.

AMA Style

Juan Camilo Castano, Alejandro Garces, Olav B. Fosso. Short-Term Hydrothermal Scheduling With Solar and Wind Farms Using Second-Order Cone Optimization With Chance-Box Constraints. IEEE Access. 2021; 9 (99):74095-74109.

Chicago/Turabian Style

Juan Camilo Castano; Alejandro Garces; Olav B. Fosso. 2021. "Short-Term Hydrothermal Scheduling With Solar and Wind Farms Using Second-Order Cone Optimization With Chance-Box Constraints." IEEE Access 9, no. 99: 74095-74109.

Journal article
Published: 11 May 2021 in Resources
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The problem of the optimal placement and sizing of photovoltaic power plants in electrical power systems from high- to medium-voltage levels is addressed in this research from the point of view of the exact mathematical optimization. To represent this problem, a mixed-integer nonlinear programming model considering the daily demand and solar radiation curves was developed. The main advantage of the proposed optimization model corresponds to the usage of the reactive power capabilities of the power electronic converter that interfaces the photovoltaic sources with the power systems, which can work with lagging or leading power factors. To model the dynamic reactive power compensation, the η-coefficient was used as a function of the nominal apparent power converter transference rate. The General Algebraic Modeling System software with the BONMIN optimization package was used as a computational tool to solve the proposed optimization model. Two simulation cases composed of 14 and 27 nodes in transmission and distribution levels were considered to validate the proposed optimization model, taking into account the possibility of installing from one to four photovoltaic sources in each system. The results show that energy losses are reduced between 13% and 56% as photovoltaic generators are added with direct effects on the voltage profile improvement.

ACS Style

Andrés Buitrago-Velandia; Oscar Montoya; Walter Gil-González. Dynamic Reactive Power Compensation in Power Systems through the Optimal Siting and Sizing of Photovoltaic Sources. Resources 2021, 10, 47 .

AMA Style

Andrés Buitrago-Velandia, Oscar Montoya, Walter Gil-González. Dynamic Reactive Power Compensation in Power Systems through the Optimal Siting and Sizing of Photovoltaic Sources. Resources. 2021; 10 (5):47.

Chicago/Turabian Style

Andrés Buitrago-Velandia; Oscar Montoya; Walter Gil-González. 2021. "Dynamic Reactive Power Compensation in Power Systems through the Optimal Siting and Sizing of Photovoltaic Sources." Resources 10, no. 5: 47.

Journal article
Published: 30 April 2021 in Electric Power Systems Research
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This paper presents a model for stabilizing multi-terminal high voltage direct-current (MT-HVDC) networks with constant power terminals (CPTs) interfaced with power electronic converters. A hierarchical structure of hierarchical control is developed, which guarantees a stable operation under load variations. This structure includes a port-Hamiltonian formulation representing the network dynamics and a passivity-based control (PBC) for the primary control. This control guarantees stability according to Lyapunov’s theory. Next, a convex optimal power flow formulation based on semidefinite programming (SDP) defines the control’s set point in the secondary/tertiary control. The proposed stabilization scheme is general for both point-to-point HVDC systems and MT-HVDC grids. Simulation results in MATLAB/Simulink demonstrate the stability of the primary control and the optimal performance of the secondary/tertiary control, considering three simulation scenarios on a reduced version of the CIGRE MT-HVDC test system: (i) variation of generation and load, (ii) short-circuit events with different fault resistances and (iii) grid topology variation. These simulations prove the applicability and efficiency of the proposed approach.

ACS Style

Oscar Danilo Montoya; Walter Gil-González; Alejandro Garces; Federico Serra; Jesus C. Hernández. Stabilization of MT-HVDC grids via passivity-based control and convex optimization. Electric Power Systems Research 2021, 196, 107273 .

AMA Style

Oscar Danilo Montoya, Walter Gil-González, Alejandro Garces, Federico Serra, Jesus C. Hernández. Stabilization of MT-HVDC grids via passivity-based control and convex optimization. Electric Power Systems Research. 2021; 196 ():107273.

Chicago/Turabian Style

Oscar Danilo Montoya; Walter Gil-González; Alejandro Garces; Federico Serra; Jesus C. Hernández. 2021. "Stabilization of MT-HVDC grids via passivity-based control and convex optimization." Electric Power Systems Research 196, no. : 107273.

Journal article
Published: 25 April 2021 in Electronics
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This paper proposes adaptive virtual inertia for the synchronverter model implemented in a wind turbine generator system integrated into the grid through a back-to-back converter. A linear dynamic system is developed for the proposed adaptive virtual inertia, which employs the frequency deviation and the rotor angle deviation of the synchronverter model as the state variables and the virtual inertia and frequency droop gain as the control variables. In addition, the proposed adaptive virtual inertia uses a linear quadratic regulator to ensure the optimal balance between fast frequency response and wind turbine generator system stress during disturbances. Hence, it minimizes frequency deviations with minimum effort. Several case simulations are proposed and carried out in MATLAB/Simulink software, and the results demonstrate the effectiveness and feasibility of the proposed adaptive virtual inertia synchronverter based on a linear quadratic regulator. The maximum and minimum frequency, the rate change of the frequency, and the integral of time-weighted absolute error are computed to quantify the performance of the proposed adaptive virtual inertia. These indexes are reduced by 46.61%, 52.67%, 79.41%, and 34.66%, in the worst case, when the proposed adaptive model is compared to the conventional synchronverter model.

ACS Style

Walter Gil-González; Oscar Montoya; Andrés Escobar-Mejía; Jesús Hernández. LQR-Based Adaptive Virtual Inertia for Grid Integration of Wind Energy Conversion System Based on Synchronverter Model. Electronics 2021, 10, 1022 .

AMA Style

Walter Gil-González, Oscar Montoya, Andrés Escobar-Mejía, Jesús Hernández. LQR-Based Adaptive Virtual Inertia for Grid Integration of Wind Energy Conversion System Based on Synchronverter Model. Electronics. 2021; 10 (9):1022.

Chicago/Turabian Style

Walter Gil-González; Oscar Montoya; Andrés Escobar-Mejía; Jesús Hernández. 2021. "LQR-Based Adaptive Virtual Inertia for Grid Integration of Wind Energy Conversion System Based on Synchronverter Model." Electronics 10, no. 9: 1022.

Journal article
Published: 23 April 2021 in Sustainable Energy, Grids and Networks
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Widespread application of residential photovoltaic (PV) systems and electric vehicles (EVs) has led the distribution system operators (DSOs) to face new technical challenges such as overloading and significant voltage variations, especially on low voltage (LV) grids. This adverse effect may be mitigated by employing the aggregators as intermediary actors to coordinate the operation at the distribution level. Therefore, this paper proposes a centralised coordination strategy to mitigate both PV and EV impacts, such as voltage rising/dropping at noon or evening, respectively, by defining the optimal export limit of PV power and EVs charging among multiple aggregators at the DSO level. The latter is in charge to dictate the optimal aggregated signals to every aggregator by employing a mixed-integer quadratic programming (MIQP) approach. The aggregated PV power is evenly managed for each aggregator by weighting. Two convex optimisation models are defined to satisfy both power and voltage constraints of the LV network. Each proposed optimisation approach can be utilised when there is or no detailed information about the LV network topology. The concepts discussed in this paper are tested on a real low voltage network considering a critical penetration level of EVs and PVs.

ACS Style

Andrés Felipe Cortés Borray; Julia Merino; Esther Torres; Alejandro Garcés; Javier Mazón. Centralised coordination of EVs charging and PV active power curtailment over multiple aggregators in low voltage networks. Sustainable Energy, Grids and Networks 2021, 27, 100470 .

AMA Style

Andrés Felipe Cortés Borray, Julia Merino, Esther Torres, Alejandro Garcés, Javier Mazón. Centralised coordination of EVs charging and PV active power curtailment over multiple aggregators in low voltage networks. Sustainable Energy, Grids and Networks. 2021; 27 ():100470.

Chicago/Turabian Style

Andrés Felipe Cortés Borray; Julia Merino; Esther Torres; Alejandro Garcés; Javier Mazón. 2021. "Centralised coordination of EVs charging and PV active power curtailment over multiple aggregators in low voltage networks." Sustainable Energy, Grids and Networks 27, no. : 100470.

Journal article
Published: 08 April 2021 in Applied Sciences
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This paper proposes a new hybrid master–slave optimization approach to address the problem of the optimal placement and sizing of distribution static compensators (D-STATCOMs) in electrical distribution grids. The optimal location of the D-STATCOMs is identified by implementing the classical and well-known Chu and Beasley genetic algorithm, which employs an integer codification to select the nodes where these will be installed. To determine the optimal sizes of the D-STATCOMs, a second-order cone programming reformulation of the optimal power flow problem is employed with the aim of minimizing the total costs of the daily energy losses. The objective function considered in this study is the minimization of the annual operative costs associated with energy losses and installation investments in D-STATCOMs. This objective function is subject to classical power balance constraints and device capabilities, which generates a mixed-integer nonlinear programming model that is solved with the proposed genetic-convex strategy. Numerical validations in the 33-node test feeder with radial configuration show the proposed genetic-convex model’s effectiveness to minimize the annual operative costs of the grid when compared with the optimization solvers available in GAMS software.

ACS Style

Oscar Montoya; Harold Chamorro; Lazaro Alvarado-Barrios; Walter Gil-González; César Orozco-Henao. Genetic-Convex Model for Dynamic Reactive Power Compensation in Distribution Networks Using D-STATCOMs. Applied Sciences 2021, 11, 3353 .

AMA Style

Oscar Montoya, Harold Chamorro, Lazaro Alvarado-Barrios, Walter Gil-González, César Orozco-Henao. Genetic-Convex Model for Dynamic Reactive Power Compensation in Distribution Networks Using D-STATCOMs. Applied Sciences. 2021; 11 (8):3353.

Chicago/Turabian Style

Oscar Montoya; Harold Chamorro; Lazaro Alvarado-Barrios; Walter Gil-González; César Orozco-Henao. 2021. "Genetic-Convex Model for Dynamic Reactive Power Compensation in Distribution Networks Using D-STATCOMs." Applied Sciences 11, no. 8: 3353.

Journal article
Published: 07 April 2021 in Electric Power Systems Research
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A fault in a power system generates economic losses, security problems, social problems and can even take human lives. Therefore, it is necessary to have an efficient fault location strategy to reduce the exposure time and recurrence of the fault. This paper presents an impedance-based method to estimate the fault location in transmission lines. The mathematical formulation considers the distributed parameters transmission line model for the estimation of the fault distance, and it is obtained by the application of Gauss-Newton method. Said method considers available voltage and current measurements at both terminals of the transmission line as well as the line parameters. Moreover, the method can be used for locating high and low impedance faults. Additionally, it is proposed an adjustable HIF model to validate its performance, which allows to generate synthetic high impedance faults by setting specific features of a HIF from simple input parameters. The error in fault location accuracy is under 0.1% for more than 90% of the performance test cases. The easy implementation of this method and encouraging test results indicate its potential for real-life applications.

ACS Style

Jose Doria-García; Cesar Orozco-Henao; Roberto Leborgne; Oscar Danilo Montoya; Walter Gil-González. High impedance fault modeling and location for transmission line✰. Electric Power Systems Research 2021, 196, 107202 .

AMA Style

Jose Doria-García, Cesar Orozco-Henao, Roberto Leborgne, Oscar Danilo Montoya, Walter Gil-González. High impedance fault modeling and location for transmission line✰. Electric Power Systems Research. 2021; 196 ():107202.

Chicago/Turabian Style

Jose Doria-García; Cesar Orozco-Henao; Roberto Leborgne; Oscar Danilo Montoya; Walter Gil-González. 2021. "High impedance fault modeling and location for transmission line✰." Electric Power Systems Research 196, no. : 107202.

Journal article
Published: 22 March 2021 in Electric Power Systems Research
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Distributed energy resources consideration by fault location formulations is a technical challenge. Stochastic behavior complicates deterministic solutions, while probabilistic approaches are yet to be fully explored. This paper presents analytical physics-based models towards the solution to this challenge. Presented models consider information availability from distributed energy resources to improve the fault location reliability. Information considered is divided into two categories: synchronized measurements provided by intelligent electronic devices located in the substation and in each terminal of distributed energy resources; and linear analytical-based models of distributed energy resources. Distributed energy resources models are used only when remote measurements are not available. Different distributed energy resources technologies and their operation modes are modeled. The presented fault location solution is validated on the IEEE 34-nodes test feeder modified. Easy-to-implement model, without hard-to-design parameters, built on the classical impedance-based fault location solution, indicates potential for real-life applications.

ACS Style

A.S. Bretas; C. Orozco-Henao; J. Marín-Quintero; O.D. Montoya; W. Gil-González; N.G. Bretas. Microgrids physics model-based fault location formulation: Analytic-based distributed energy resources effect compensation. Electric Power Systems Research 2021, 195, 107178 .

AMA Style

A.S. Bretas, C. Orozco-Henao, J. Marín-Quintero, O.D. Montoya, W. Gil-González, N.G. Bretas. Microgrids physics model-based fault location formulation: Analytic-based distributed energy resources effect compensation. Electric Power Systems Research. 2021; 195 ():107178.

Chicago/Turabian Style

A.S. Bretas; C. Orozco-Henao; J. Marín-Quintero; O.D. Montoya; W. Gil-González; N.G. Bretas. 2021. "Microgrids physics model-based fault location formulation: Analytic-based distributed energy resources effect compensation." Electric Power Systems Research 195, no. : 107178.

Journal article
Published: 02 March 2021 in Applied Sciences
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The problem of reactive power compensation in electric distribution networks is addressed in this research paper from the point of view of the combinatorial optimization using a new discrete-continuous version of the vortex search algorithm (DCVSA). To explore and exploit the solution space, a discrete-continuous codification of the solution vector is proposed, where the discrete part determines the nodes where the distribution static compensator (D-STATCOM) will be installed, and the continuous part of the codification determines the optimal sizes of the D-STATCOMs. The main advantage of such codification is that the mixed-integer nonlinear programming model (MINLP) that represents the problem of optimal placement and sizing of the D-STATCOMs in distribution networks only requires a classical power flow method to evaluate the objective function, which implies that it can be implemented in any programming language. The objective function is the total costs of the grid power losses and the annualized investment costs in D-STATCOMs. In addition, to include the impact of the daily load variations, the active and reactive power demand curves are included in the optimization model. Numerical results in two radial test feeders with 33 and 69 buses demonstrate that the proposed DCVSA can solve the MINLP model with best results when compared with the MINLP solvers available in the GAMS software. All the simulations are implemented in MATLAB software using its programming environment.

ACS Style

Oscar Montoya; Walter Gil-González; Jesus Hernández. Efficient Operative Cost Reduction in Distribution Grids Considering the Optimal Placement and Sizing of D-STATCOMs Using a Discrete-Continuous VSA. Applied Sciences 2021, 11, 2175 .

AMA Style

Oscar Montoya, Walter Gil-González, Jesus Hernández. Efficient Operative Cost Reduction in Distribution Grids Considering the Optimal Placement and Sizing of D-STATCOMs Using a Discrete-Continuous VSA. Applied Sciences. 2021; 11 (5):2175.

Chicago/Turabian Style

Oscar Montoya; Walter Gil-González; Jesus Hernández. 2021. "Efficient Operative Cost Reduction in Distribution Grids Considering the Optimal Placement and Sizing of D-STATCOMs Using a Discrete-Continuous VSA." Applied Sciences 11, no. 5: 2175.

Journal article
Published: 24 February 2021 in Applied Sciences
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Phase balancing is a classical optimization problem in power distribution grids that involve phase swapping of the loads and generators to reduce power loss. The problem is a non-linear integer and, hence, it is usually solved using heuristic algorithms. This paper proposes a mathematical reformulation that transforms the phase-balancing problem in low-voltage distribution networks into a mixed-integer convex quadratic optimization model. To consider both conventional secondary feeders and microgrids, renewable energies and their subsequent stochastic nature are included in the model. The power flow equations are linearized, and the combinatorial part is represented using a Birkhoff polytope B 3 that allows the selection of phase swapping in each node. The numerical experiments on the CIGRE low-voltage test system demonstrate the use of the proposed formulation.

ACS Style

Alejandro Garces; Walter Gil-González; Oscar Montoya; Harold Chamorro; Lazaro Alvarado-Barrios. A Mixed-Integer Quadratic Formulation of the Phase-Balancing Problem in Residential Microgrids. Applied Sciences 2021, 11, 1972 .

AMA Style

Alejandro Garces, Walter Gil-González, Oscar Montoya, Harold Chamorro, Lazaro Alvarado-Barrios. A Mixed-Integer Quadratic Formulation of the Phase-Balancing Problem in Residential Microgrids. Applied Sciences. 2021; 11 (5):1972.

Chicago/Turabian Style

Alejandro Garces; Walter Gil-González; Oscar Montoya; Harold Chamorro; Lazaro Alvarado-Barrios. 2021. "A Mixed-Integer Quadratic Formulation of the Phase-Balancing Problem in Residential Microgrids." Applied Sciences 11, no. 5: 1972.

Journal article
Published: 15 February 2021 in Electric Power Systems Research
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This paper addresses the problem of optimal conductor selection in direct current (DC) distribution networks with radial topology. A nonlinear mixed-integer programming model (MINLP) is developed through a branch-to-node incidence matrix. An important contribution is that the proposed MINLP model integrates a set of constraints related to the telescopic structure of the network, which allows reducing installation costs. The proposed model also includes a time-domain dependency that helps analyze the DC network under different load conditions, including renewable generation and battery energy storage systems, and different voltage regulation operative consigns. The objective function of the proposed model is made up of the total investment in conductors and the total cost of energy losses in one year of operation. These components of the objective function show multi-objective behavior. For this reason, different simulation scenarios are performed to identify their effects on the final grid configuration. An illustrative 10-nodes medium-voltage DC grid with 9 lines is used to carry out all the simulations through the General Algebraic Modeling System known as GAMS.

ACS Style

Oscar Danilo Montoya; Walter Gil-González; Luis F. Grisales-Noreña. On the mathematical modeling for optimal selecting of calibers of conductors in DC radial distribution networks: An MINLP approach. Electric Power Systems Research 2021, 194, 107072 .

AMA Style

Oscar Danilo Montoya, Walter Gil-González, Luis F. Grisales-Noreña. On the mathematical modeling for optimal selecting of calibers of conductors in DC radial distribution networks: An MINLP approach. Electric Power Systems Research. 2021; 194 ():107072.

Chicago/Turabian Style

Oscar Danilo Montoya; Walter Gil-González; Luis F. Grisales-Noreña. 2021. "On the mathematical modeling for optimal selecting of calibers of conductors in DC radial distribution networks: An MINLP approach." Electric Power Systems Research 194, no. : 107072.

Journal article
Published: 11 January 2021 in Applied Sciences
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The optimal placement and sizing of distributed generators is a classical problem in power distribution networks that is usually solved using heuristic algorithms due to its high complexity. This paper proposes a different approach based on a mixed-integer second-order cone programming (MI-SOCP) model that ensures the global optimum of the relaxed optimization model. Second-order cone programming (SOCP) has demonstrated to be an efficient alternative to cope with the non-convexity of the power flow equations in power distribution networks. Of relatively new interest to the power systems community is the extension to MI-SOCP models. The proposed model is an approximation. However, numerical validations in the IEEE 33-bus and IEEE 69-bus test systems for unity and variable power factor confirm that the proposed MI-SOCP finds the best solutions reported in the literature. Being an exact technique, the proposed model allows minimum processing times and zero standard deviation, i.e., the same optimum is guaranteed at each time that the MI-SOCP model is solved (a significant advantage in comparison to metaheuristics). Additionally, load and photovoltaic generation curves for the IEEE 69-node test system are included to demonstrate the applicability of the proposed MI-SOCP to solve the problem of the optimal location and sizing of renewable generators using the multi-period optimal power flow formulation. Therefore, the proposed MI-SOCP also guarantees the global optimum finding, in contrast to local solutions achieved with mixed-integer nonlinear programming solvers available in the GAMS optimization software. All the simulations were carried out via MATLAB software with the CVX package and Gurobi solver.

ACS Style

Walter Gil-González; Alejandro Garces; Oscar Danilo Montoya; Jesus C. Hernández. A Mixed-Integer Convex Model for the Optimal Placement and Sizing of Distributed Generators in Power Distribution Networks. Applied Sciences 2021, 11, 627 .

AMA Style

Walter Gil-González, Alejandro Garces, Oscar Danilo Montoya, Jesus C. Hernández. A Mixed-Integer Convex Model for the Optimal Placement and Sizing of Distributed Generators in Power Distribution Networks. Applied Sciences. 2021; 11 (2):627.

Chicago/Turabian Style

Walter Gil-González; Alejandro Garces; Oscar Danilo Montoya; Jesus C. Hernández. 2021. "A Mixed-Integer Convex Model for the Optimal Placement and Sizing of Distributed Generators in Power Distribution Networks." Applied Sciences 11, no. 2: 627.

Research article
Published: 22 December 2020 in International Transactions on Electrical Energy Systems
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This paper proposes a general model for microgrids in the 0dq reference frame for stationary state and small dynamic variations. The proposed model considers the dynamics of the distribution lines, including mutual coupling and unbalanced loads, and the dynamics of the converters required to integrate renewable sources and energy storage devices (eg, batteries and/or supercapacitors). A fixed‐point algorithm is proposed for finding the equilibrium point. This algorithm constitutes a load flow in the 0dq reference frame used to develop an average model of the grid. Finally, a small‐signal stability analysis is presented. Simulations results on the CIGRE low‐voltage benchmark microgrid demonstrate the performance of the model in terms of accuracy and fast computation compared to simulations in the ABC reference frame.

ACS Style

Manuel‐Fernando Bravo‐López; Alejandro Garcés; Juan‐José Mora‐Flórez. Simplified dynamic models for three‐phase microgrids. International Transactions on Electrical Energy Systems 2020, 31, 1 .

AMA Style

Manuel‐Fernando Bravo‐López, Alejandro Garcés, Juan‐José Mora‐Flórez. Simplified dynamic models for three‐phase microgrids. International Transactions on Electrical Energy Systems. 2020; 31 (2):1.

Chicago/Turabian Style

Manuel‐Fernando Bravo‐López; Alejandro Garcés; Juan‐José Mora‐Flórez. 2020. "Simplified dynamic models for three‐phase microgrids." International Transactions on Electrical Energy Systems 31, no. 2: 1.

Journal article
Published: 09 December 2020 in Electronics
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This paper explores a methodology to locate battery energy storage systems (BESS) in rural alternating current (AC) distribution networks fed by diesel generators to minimize total greenhouse gas emissions. A mixed-integer nonlinear programming (MINLP) model is formulated to represent the problem of greenhouse gas emissions minimization, considering power balance and devices capabilities as constraints. To model the BESS systems, a linear relationship is considered between the state of charge and the power injection/consumption using a charging/discharging coefficient. The solution of the MINLP model is reached through the general algebraic modeling system by employing the BONMIN solver. Numerical results in a medium-voltage AC distribution network composed of 33 nodes and 32 branches operated with 12.66 kV demonstrate the effectiveness of including BESS systems to minimize greenhouse gas emissions in diesel generators that feeds rural distribution networks.

ACS Style

Oscar Danilo Montoya; Walter Gil-González; Jesus C. Hernández. Optimal Selection and Location of BESS Systems in Medium-Voltage Rural Distribution Networks for Minimizing Greenhouse Gas Emissions. Electronics 2020, 9, 2097 .

AMA Style

Oscar Danilo Montoya, Walter Gil-González, Jesus C. Hernández. Optimal Selection and Location of BESS Systems in Medium-Voltage Rural Distribution Networks for Minimizing Greenhouse Gas Emissions. Electronics. 2020; 9 (12):2097.

Chicago/Turabian Style

Oscar Danilo Montoya; Walter Gil-González; Jesus C. Hernández. 2020. "Optimal Selection and Location of BESS Systems in Medium-Voltage Rural Distribution Networks for Minimizing Greenhouse Gas Emissions." Electronics 9, no. 12: 2097.

Journal article
Published: 03 December 2020 in Electronics
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This study analyzes the numerical convergence and processing time required by several classical and new solution methods proposed in the literature to solve the power-flow problem (PF) in direct-current (DC) networks considering radial and mesh topologies. Three classical numerical methods were studied: Gauss–Jacobi, Gauss–Seidel, and Newton–Raphson. In addition, two unconventional methods were selected. They are iterative and allow solving the DC PF in radial and mesh configurations. The first method uses a Taylor series expansion and a set of decoupling equations to linearize around the desired operating point. The second method manipulates the set of non-linear equations of the DC PF to transform it into a conventional fixed-point form. Moreover, this method is used to develop a successive approximation methodology. For the particular case of radial topology, three methods based on triangular matrix formulation, graph theory, and scanning algorithms were analyzed. The main objective of this study was to identify the methods with the best performance in terms of quality of solution (i.e., numerical convergence) and processing time to solve the DC power flow in mesh and radial distribution networks. We aimed at offering to the reader a set of PF methodologies to analyze electrical DC grids. The PF performance of the analyzed solution methods was evaluated through six test feeders; all of them were employed in prior studies for the same application. The simulation results show the adequate performance of the power-flow methods reviewed in this study, and they permit the selection of the best solution method for radial and mesh structures.

ACS Style

Luis Fernando Grisales-Noreña; Oscar Danilo Montoya; Walter Julian Gil-González; Alberto-Jesus Perea-Moreno; Miguel-Angel Perea-Moreno. A Comparative Study on Power Flow Methods for Direct-Current Networks Considering Processing Time and Numerical Convergence Errors. Electronics 2020, 9, 2062 .

AMA Style

Luis Fernando Grisales-Noreña, Oscar Danilo Montoya, Walter Julian Gil-González, Alberto-Jesus Perea-Moreno, Miguel-Angel Perea-Moreno. A Comparative Study on Power Flow Methods for Direct-Current Networks Considering Processing Time and Numerical Convergence Errors. Electronics. 2020; 9 (12):2062.

Chicago/Turabian Style

Luis Fernando Grisales-Noreña; Oscar Danilo Montoya; Walter Julian Gil-González; Alberto-Jesus Perea-Moreno; Miguel-Angel Perea-Moreno. 2020. "A Comparative Study on Power Flow Methods for Direct-Current Networks Considering Processing Time and Numerical Convergence Errors." Electronics 9, no. 12: 2062.

Journal article
Published: 02 December 2020 in Applied Sciences
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This research addresses the problem of the optimal location and sizing distributed generators (DGs) in direct current (DC) distribution networks from the combinatorial optimization. It is proposed a master–slave optimization approach in order to solve the problems of placement and location of DGs, respectively. The master stage applies to the classical Chu & Beasley genetic algorithm (GA), while the slave stage resolves a second-order cone programming reformulation of the optimal power flow problem for DC grids. This master–slave approach generates a hybrid optimization approach, named GA-SOCP. The main advantage of optimal dimensioning of DGs via SOCP is that this method makes part of the exact mathematical optimization that guarantees the possibility of finding the global optimal solution due to the solution space’s convex structure, which is a clear improvement regarding classical metaheuristic optimization methodologies. Numerical comparisons with hybrid and exact optimization approaches reported in the literature demonstrate the proposed hybrid GA-SOCP approach’s effectiveness and robustness to achieve the global optimal solution. Two test feeders compose of 21 and 69 nodes that can locate three distributed generators are considered. All of the computational validations have been carried out in the MATLAB software and the CVX tool for convex optimization.

ACS Style

Oscar Danilo Montoya; Walter Gil-González; Luis Fernando Grisales-Noreña. Hybrid GA-SOCP Approach for Placement and Sizing of Distributed Generators in DC Networks. Applied Sciences 2020, 10, 8616 .

AMA Style

Oscar Danilo Montoya, Walter Gil-González, Luis Fernando Grisales-Noreña. Hybrid GA-SOCP Approach for Placement and Sizing of Distributed Generators in DC Networks. Applied Sciences. 2020; 10 (23):8616.

Chicago/Turabian Style

Oscar Danilo Montoya; Walter Gil-González; Luis Fernando Grisales-Noreña. 2020. "Hybrid GA-SOCP Approach for Placement and Sizing of Distributed Generators in DC Networks." Applied Sciences 10, no. 23: 8616.