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19 pages, 1187 KiB

Open AccessArticle

Control of Photovoltaic Plants Interconnected via VSC to Improve Power Oscillations in a Power System

by Ángeles Medina-Quesada, Walter Gil-González, Oscar Danilo Montoya, Alexander Molina-Cabrera and Jesus C. Hernández

Electronics 2022, 11(11), 1744; https://doi.org/10.3390/electronics11111744 - 31 May 2022

Cited by 2 | Viewed by 1677

Abstract

This paper presents an integrated methodology applied to photovoltaic (PV) plants for improving the dynamic performance of electric power systems. The proposed methodology is based on primary frequency control, which adds an ancillary signal to the voltage reference of the DC-link for the [...] Read more.

This paper presents an integrated methodology applied to photovoltaic (PV) plants for improving the dynamic performance of electric power systems. The proposed methodology is based on primary frequency control, which adds an ancillary signal to the voltage reference of the DC-link for the voltage source converter (VSC) in order to reduce power oscillations. This ancillary signal is computed by relating the energy stored in the VSC of the DC-link and the energy stored in the synchronous machine’s shaft. In addition, the methodology considers the operating limits of the VSC, which prioritizes active power over reactive power. Furthermore, the VSC control is assessed with interconnection and damping assignment passivity-based control (IDA-PBC), as well as compared to conventional PI control. IDA-PBC is employed to design a Lyapunov asymptotically stable controller using the Hamiltonian structural properties of the open-loop model of the VSC. A 12-bus test system that considers PV plants is employed to compare the proposed IDA-PBC control with a classical proportional-integral control approach. The impact of the proposed methodology is analyzed in four scenarios with different PV penetration levels (10%, 30%, 50%, and 80%) and four large disturbances in the test power system. In addition, a decrease in the inertia of the synchronous machines from 100 to 25% is analyzed. The time-domain simulation results show that the frequency oscillations are reduced by 16.8%, 38.43%, 37.53%, and 76.94% in comparison with the case where the proposed methodology was not implemented. The simulations were conducted using the SimPowerSystems toolbox of the MATLAB/Simulink software. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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14 pages, 358 KiB

Open AccessArticle

Efficient Integration of PV Sources in Distribution Networks to Reduce Annual Investment and Operating Costs Using the Modified Arithmetic Optimization Algorithm

by Oscar Danilo Montoya, Diego Armando Giral-Ramírez and Jesus C. Hernández

Electronics 2022, 11(11), 1680; https://doi.org/10.3390/electronics11111680 - 25 May 2022

Cited by 11 | Viewed by 1809

Abstract

The optimal integration of photovoltaic generation systems is a challenge for distribution utilities since these devices have a direct impact on company finances due to the large amount of investment required at the beginning of the planning project. In this investigation, the problem [...] Read more.

The optimal integration of photovoltaic generation systems is a challenge for distribution utilities since these devices have a direct impact on company finances due to the large amount of investment required at the beginning of the planning project. In this investigation, the problem regarding the optimal siting and sizing of photovoltaic resources in medium-voltage levels is addressed from an economical point of view, where the optimization model that represents said problem corresponds to a mixed-integer nonlinear programming model. The maximum allowed size for single photovoltaic units in the distribution network is set at 2400 kW. The investment costs, energy purchase costs and maintenance costs for photovoltaic units, are considered in the objective function. Typical constraints such as power balance, generation capacities, voltage regulation, among others, are considered in the mathematical formulation. The solution of the optimization model is addressed by implementing a modified version of the Arithmetic Optimization Algorithm, which includes a new exploration and exploitation characteristic based on the best current solution in iteration t, i.e.,

x_{best}^{t}

. This improvement is based on a Gaussian distribution operator that generates new candidate solutions with the center at

x_{best}^{t}

, which are uniformly distributed. The main contribution of this research is the proposal of a new hybrid optimization algorithm to solve the exact optimization model, which is based on a combination of the Arithmetic Optimization algorithm with the Vortex Search algorithm and showed excellent numerical results in the IEEE 34-bus grid. The analysis of quantitative results allows us to conclude that the strategy proposed in this work has a greater effectiveness with respect to the General Algebraic Modeling System software solvers, as well as with metaheuristic optimizers such as Genetic Algorithms, the Newton–Metaheuristic Algorithm, and the original Arithmetic Optimization Algorithm. MATLAB was used as a simulation tool. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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18 pages, 581 KiB

Open AccessArticle

A Two-Stage Approach to Locate and Size PV Sources in Distribution Networks for Annual Grid Operative Costs Minimization

by Oscar Danilo Montoya, Edwin Rivas-Trujillo and Jesus C. Hernández

Electronics 2022, 11(6), 961; https://doi.org/10.3390/electronics11060961 - 21 Mar 2022

Cited by 5 | Viewed by 2059

Abstract

This paper contributes with a new two-stage optimization methodology to solve the problem of the optimal placement and sizing of solar photovoltaic (PV) generation units in medium-voltage distribution networks. The optimization problem is formulated with a mixed-integer nonlinear programming (MINLP) model, where it [...] Read more.

This paper contributes with a new two-stage optimization methodology to solve the problem of the optimal placement and sizing of solar photovoltaic (PV) generation units in medium-voltage distribution networks. The optimization problem is formulated with a mixed-integer nonlinear programming (MINLP) model, where it combines binary variables regarding the nodes where the PV generators will be located and continuous variables associated with the power flow solution. To solve the MINLP model a decoupled methodology is used where the binary problem is firstly solved with mixed-integer quadratic approximation; and once the nodes where the PV sources will be located are known, the dimensioning problem of the PV generators is secondly solved through an interior point method applied to the classical multi-period power flow formulation. Numerical results in the IEEE 33-bus and IEEE 85-bus systems demonstrate that the proposed approach improves the current literature results reached with combinatorial methods such as the Chu and Beasley genetic algorithm, the vortex search algorithm, the Newton-metaheuristic algorithm as well as the exact solution of the MINLP model with the GAMS software and the BONMIN solver. All the numerical simulations are implemented in the MATLAB programming environment and the convex equivalent models are solved with the CVX tool. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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18 pages, 2687 KiB

Open AccessArticle

A Flexible Operation and Sizing of Battery Energy Storage System Based on Butterfly Optimization Algorithm

by Basit Olakunle Alawode, Umar Taiwo Salman and Muhammad Khalid

Electronics 2022, 11(1), 109; https://doi.org/10.3390/electronics11010109 - 30 Dec 2021

Cited by 14 | Viewed by 2311

Abstract

There is a surge in the total energy demand of the world due to the increase in the world’s population and the ever-increasing human dependence on technology. Conventional non-renewable energy sources still contribute a larger amount to the total energy production. Due to [...] Read more.

There is a surge in the total energy demand of the world due to the increase in the world’s population and the ever-increasing human dependence on technology. Conventional non-renewable energy sources still contribute a larger amount to the total energy production. Due to their greenhouse gas emissions and environmental pollution, the substitution of these sources with renewable energy sources (RES) is desired. However, RES, such as wind energy, are uncertain, intermittent, and unpredictable. Hence, there is a need to optimize their usage when they are available. This can be carried out through a flexible operation of a microgrid system with the power grid to gradually reduce the contribution of the conventional sources in the power system using energy storage systems (ESS). To integrate the RES in a cost-effective approach, the ESS must be optimally sized and operated within its safe limitations. This study, therefore, presents a flexible method for the optimal sizing and operation of battery ESS (BESS) in a wind-penetrated microgrid system using the butterfly optimization (BO) algorithm. The BO algorithm was utilized for its simple and fast implementation and for its ability to obtain global optimization parameters. In the formulation of the optimization problem, the study considers the depth of discharge and life-cycle of the BESS. Simulation results for three different scenarios were studied, analyzed, and compared. The resulting optimized BESS connected scenario yielded the most cost-effective strategy among all scenarios considered. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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16 pages, 503 KiB

Open AccessArticle

Optimal Placement of Reclosers in a Radial Distribution System for Reliability Improvement

by Afroz Alam, Mohd Tariq, Mohammad Zaid, Preeti Verma, Marwan Alsultan, Shafiq Ahmad, Adil Sarwar and Md. Alamgir Hossain

Electronics 2021, 10(24), 3182; https://doi.org/10.3390/electronics10243182 - 20 Dec 2021

Cited by 11 | Viewed by 4033

Abstract

There is a need for the optimal positioning of protective devices to maximize customers satisfaction per their demands. Such arrangement advances the distribution system reliability to maximum achievable. Thus, radial distribution system (RDS) reliability can be improved by placing reclosers at suitable feeder [...] Read more.

There is a need for the optimal positioning of protective devices to maximize customers satisfaction per their demands. Such arrangement advances the distribution system reliability to maximum achievable. Thus, radial distribution system (RDS) reliability can be improved by placing reclosers at suitable feeder sections. This article presents comprehensive details of an attempt to determine the reclosers’ optimal location in an RDS to maximize the utility profit by reliability improvement. Assessment of different reliability indices such as SAIDI, SAIFI, CAIFI, CAIDI, etc., with recloser placement, exhibits a considerable improvement in these indices in contrast with the absence of recloser. Consequently, a new bidirectional formulation has been proposed for the optimized arrangement of reclosers’. This formulation efficiently handles the bidirectional power flow, resulting from distributed generation (DG) unit (s) in the system. The proposed model has been solved for a test system by utilizing the Genetic algorithm (GA) optimization method. Later, test results conclude that reclosers’ optimal placement contributes significantly towards utility profit with minimum investment and outage costs. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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15 pages, 334 KiB

Open AccessArticle

An Approximate Mixed-Integer Convex Model to Reduce Annual Operating Costs in Radial Distribution Networks Using STATCOMs

by Oscar Danilo Montoya, Lázaro Alvarado-Barrios and Jesus C. Hernández

Electronics 2021, 10(24), 3102; https://doi.org/10.3390/electronics10243102 - 13 Dec 2021

Cited by 8 | Viewed by 2089

Abstract

The problem of optimal siting and sizing of distribution static compensators (STATCOMs) is addressed in this research from the point of view of exact mathematical optimization. The exact mixed-integer nonlinear programming model (MINLP) is decoupled into two convex optimization sub-problems, named the location [...] Read more.

The problem of optimal siting and sizing of distribution static compensators (STATCOMs) is addressed in this research from the point of view of exact mathematical optimization. The exact mixed-integer nonlinear programming model (MINLP) is decoupled into two convex optimization sub-problems, named the location problem and the sizing problem. The location problem is addressed by relaxing the exact MINLP model, assuming that all the voltages are equal to

1 ∠ 0^{\circ}

, which allows obtaining a mixed-integer quadratic programming model as a function of the active and reactive power flows. The solution of this model provides the best set of nodes to locate all the STATCOMs. When all the nodes are selected, it solves the optimal reactive power problem through a second-order cone programming relaxation of the exact optimal power flow problem; the solution of the SOCP model provides the optimal sizes of the STATCOMs. Finally, it refines the exact objective function value due to the intrinsic non-convexities associated with the costs of the STATCOMs that were relaxed through the application of Taylor’s series expansion in the location and sizing stages. The numerical results in the IEEE 33- and 69-bus systems demonstrate the effectiveness and robustness of the proposed optimization problem when compared with large-scale MINLP solvers in GAMS and the discrete-continuous version of the vortex search algorithm (DCVSA) recently reported in the current literature. With respect to the benchmark cases of the test feeders, the proposed approach reaches the best reductions with

14.17 %

and

15.79 %

in the annual operative costs, which improves the solutions of the DCVSA, which are

13.71 %

and

15.30 %

, respectively. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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27 pages, 922 KiB

Open AccessArticle

Optimal Power Dispatch of Distributed Generators in Direct Current Networks Using a Master–Slave Methodology That Combines the Salp Swarm Algorithm and the Successive Approximation Method

by Andrés Alfonso Rosales Muñoz, Luis Fernando Grisales-Noreña, Jhon Montano, Oscar Danilo Montoya and Diego Armando Giral-Ramírez

Electronics 2021, 10(22), 2837; https://doi.org/10.3390/electronics10222837 - 18 Nov 2021

Cited by 8 | Viewed by 1601

Abstract

This paper addresses the Optimal Power Flow (OPF) problem in Direct Current (DC) networks by considering the integration of Distributed Generators (DGs). In order to model said problem, this study employs a mathematical formulation that has, as the objective function, the reduction in [...] Read more.

This paper addresses the Optimal Power Flow (OPF) problem in Direct Current (DC) networks by considering the integration of Distributed Generators (DGs). In order to model said problem, this study employs a mathematical formulation that has, as the objective function, the reduction in power losses associated with energy transport and that considers the set of constraints that compose DC networks in an environment of distributed generation. To solve this mathematical formulation, a master–slave methodology that combines the Salp Swarm Algorithm (SSA) and the Successive Approximations (SA) method was used here. The effectiveness, repeatability, and robustness of the proposed solution methodology was validated using two test systems (the 21- and 69-node systems), five other optimization methods reported in the specialized literature, and three different penetration levels of distributed generation: 20%, 40%, and 60% of the power provided by the slack node in the test systems in an environment with no DGs (base case). All simulations were executed 100 times for each solution methodology in the different test scenarios. The purpose of this was to evaluate the repeatability of the solutions provided by each technique by analyzing their minimum and average power losses and required processing times. The results show that the proposed solution methodology achieved the best trade-off between (minimum and average) power loss reduction and processing time for networks of any size. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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17 pages, 677 KiB

Open AccessArticle

A Comparative Study on Power Flow Methods Applied to AC Distribution Networks with Single-Phase Representation

by Oscar Danilo Montoya, Alexander Molina-Cabrera and Jesus C. Hernández

Electronics 2021, 10(21), 2573; https://doi.org/10.3390/electronics10212573 - 21 Oct 2021

Cited by 11 | Viewed by 2630

Abstract

This paper presents a comparative analysis of six different iterative power flow methods applied to AC distribution networks, which have been recently reported in the scientific literature. These power flow methods are (i) successive approximations, (ii) matricial backward/forward method, (iii) triangular-based approach, (iv) [...] Read more.

This paper presents a comparative analysis of six different iterative power flow methods applied to AC distribution networks, which have been recently reported in the scientific literature. These power flow methods are (i) successive approximations, (ii) matricial backward/forward method, (iii) triangular-based approach, (iv) product linearization method, (v) hyperbolic linearization method, and (vi) diagonal approximation method. The first three methods and the last one are formulated without recurring derivatives, and they can be directly formulated in the complex domain; the fourth and fifth methods are based on the linear approximation of the power balance equations that are also formulated in the complex domain. The numerical comparison involves three main aspects: the convergence rate, processing time, and the number of iterations calculated using the classical Newton–Raphson method as the reference case. Numerical results from two test feeders composed of 34 and 85 nodes demonstrate that the derivative-free methods have linear convergence, and the methods that use derivatives in their formulation have quadratic convergence. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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12 pages, 1066 KiB

Open AccessArticle

Voltage Regulation of an Isolated DC Microgrid with a Constant Power Load: A Passivity-based Control Design

by Guillermo Luciano Magaldi, Federico Martin Serra, Cristian Hernán de Angelo, Oscar Danilo Montoya and Diego Armando Giral-Ramírez

Electronics 2021, 10(17), 2085; https://doi.org/10.3390/electronics10172085 - 28 Aug 2021

Cited by 19 | Viewed by 2809

Abstract

Passivity-based nonlinear control for an isolated microgrid system is proposed in this paper. The microgrid consists of a photovoltaic array and a battery energy storage connected to a point of common converters, supplying a constant power load. The purpose of this control strategy [...] Read more.

Passivity-based nonlinear control for an isolated microgrid system is proposed in this paper. The microgrid consists of a photovoltaic array and a battery energy storage connected to a point of common converters, supplying a constant power load. The purpose of this control strategy is to maintain the output direct current voltage in its reference value under load variations, improving battery interaction. The system is represented by its state space averaged model and the proposed controller is designed using the interconnection and damping assignment strategy, which allows obtaining controller parameters while ensuring the closed-loop system stability. The unknown constant power load is estimated using an observer based on the energy function of the system. The behavior of the proposed control strategy is validated with simulation and experimental results. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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20 pages, 2415 KiB

Open AccessArticle

Vulnerability Analysis to Maximize the Resilience of Power Systems Considering Demand Response and Distributed Generation

by Darin Jairo Mosquera Palacios, Edwin Rivas Trujillo and Jesús María López-Lezama

Electronics 2021, 10(12), 1498; https://doi.org/10.3390/electronics10121498 - 21 Jun 2021

Cited by 7 | Viewed by 2269

Abstract

Electric power systems are subject to failures, due to both deliberate and fortuitous events. This paper addresses the first case in which a disruptive agent aims at maximizing the damage to the network (expressed through the total cost of operation), while the system [...] Read more.

Electric power systems are subject to failures, due to both deliberate and fortuitous events. This paper addresses the first case in which a disruptive agent aims at maximizing the damage to the network (expressed through the total cost of operation), while the system operator takes the necessary measures to mitigate the effects of this attack. The interaction between these two agents is modeled by means of a bi-level optimization problem. On one hand, the disruptive agent is positioned in the upper-level optimization problem and must decide which elements to render out of service (lines and generators), given a limited destructive budget. On the other hand, the system operator, located in a lower-level optimization problem, reacts to the attack by deploying mitigation measures in order to minimize cost overruns in system operation. Based on the aforementioned dynamic, this paper proposes a novel approach to maximize the resiliency of the power system under intentional attacks through the implementation of distributed energy resources (DERs), namely, distributed generation (DG) and demand response (DR). Three metrics are proposed to assess resilience by assigning DERs in islands generated by the destruction of lines and generators. The results obtained in a didactic 5-bus test system and the IEEE RTS-24 bus test system demonstrate the applicability and effectiveness of the proposed methodology. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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20 pages, 589 KiB

Open AccessArticle

Optimal Placement and Sizing of D-STATCOM in Radial and Meshed Distribution Networks Using a Discrete-Continuous Version of the Genetic Algorithm

by Cristian Mateo Castiblanco-Pérez, David Esteban Toro-Rodríguez, Oscar Danilo Montoya and Diego Armando Giral-Ramírez

Electronics 2021, 10(12), 1452; https://doi.org/10.3390/electronics10121452 - 17 Jun 2021

Cited by 38 | Viewed by 3736

Abstract

In this paper, we propose a new discrete-continuous codification of the Chu–Beasley genetic algorithm to address the optimal placement and sizing problem of the distribution static compensators (D-STATCOM) in electrical distribution grids. The discrete part of the codification determines the nodes where D-STATCOM [...] Read more.

In this paper, we propose a new discrete-continuous codification of the Chu–Beasley genetic algorithm to address the optimal placement and sizing problem of the distribution static compensators (D-STATCOM) in electrical distribution grids. The discrete part of the codification determines the nodes where D-STATCOM will be installed. The continuous part of the codification regulates their sizes. The objective function considered in this study is the minimization of the annual operative costs regarding energy losses and installation investments in D-STATCOM. This objective function is subject to the classical power balance constraints and devices’ capabilities. The proposed discrete-continuous version of the genetic algorithm solves the mixed-integer non-linear programming model that the classical power balance generates. Numerical validations in the 33 test feeder with radial and meshed configurations show that the proposed approach effectively minimizes the annual operating costs of the grid. In addition, the GAMS software compares the results of the proposed optimization method, which allows demonstrating its efficiency and robustness. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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25 pages, 432 KiB

Open AccessArticle

Reduction of Losses and Operating Costs in Distribution Networks Using a Genetic Algorithm and Mathematical Optimization

by Fabio Edison Riaño, Jonathan Felipe Cruz, Oscar Danilo Montoya, Harold R. Chamorro and Lazaro Alvarado-Barrios

Electronics 2021, 10(4), 419; https://doi.org/10.3390/electronics10040419 - 9 Feb 2021

Cited by 31 | Viewed by 3956

Abstract

This study deals with the minimization of the operational and investment cost in the distribution and operation of the power flow considering the installation of fixed-step capacitor banks. This issue is represented by a nonlinear mixed-integer programming mathematical model which is solved by [...] Read more.

This study deals with the minimization of the operational and investment cost in the distribution and operation of the power flow considering the installation of fixed-step capacitor banks. This issue is represented by a nonlinear mixed-integer programming mathematical model which is solved by applying the Chu and Beasley genetic algorithm (CBGA). While this algorithm is a classical method for resolving this type of optimization problem, the solutions found using this approach are better than those reported in the literature using metaheuristic techniques and the General Algebraic Modeling System (GAMS). In addition, the time required for the CBGA to get results was reduced to a few seconds to make it a more robust, efficient, and capable tool for distribution system analysis. Finally, the computational sources used in this study were developed in the MATLAB programming environment by implementing test feeders composed of 10, 33, and 69 nodes with radial and meshed configurations. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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21 pages, 2102 KiB

Open AccessArticle

Data-Driven Trajectory Prediction of Grid Power Frequency Based on Neural Models

by Harold R. Chamorro, Alvaro D. Orjuela-Cañón, David Ganger, Mattias Persson, Francisco Gonzalez-Longatt, Lazaro Alvarado-Barrios, Vijay K. Sood and Wilmar Martinez

Electronics 2021, 10(2), 151; https://doi.org/10.3390/electronics10020151 - 12 Jan 2021

Cited by 14 | Viewed by 3833

Abstract

Frequency in power systems is a real-time information that shows the balance between generation and demand. Good system frequency observation is vital for system security and protection. This paper analyses the system frequency response following disturbances and proposes a data-driven approach for predicting [...] Read more.

Frequency in power systems is a real-time information that shows the balance between generation and demand. Good system frequency observation is vital for system security and protection. This paper analyses the system frequency response following disturbances and proposes a data-driven approach for predicting it by using machine learning techniques like Nonlinear Auto-regressive (NAR) Neural Networks (NN) and Long Short Term Memory (LSTM) networks from simulated and measured Phasor Measurement Unit (PMU) data. The proposed method uses a horizon-window that reconstructs the frequency input time-series data in order to predict the frequency features such as Nadir. Simulated scenarios are based on the gradual inertia reduction by including non-synchronous generation into the Nordic 32 test system, whereas the PMU collected data is taken from different locations in the Nordic Power System (NPS). Several horizon-windows are experimented in order to observe an adequate margin of prediction. Scenarios considering noisy signals are also evaluated in order to provide a robustness index of predictability. Results show the proper performance of the method and the adequate level of prediction based on the Root Mean Squared Error (RMSE) index. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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24 pages, 9539 KiB

Open AccessFeature PaperArticle

Modeling of PV Module and DC/DC Converter Assembly for the Analysis of Induced Transient Response Due to Nearby Lightning Strike

by Alessandro Formisano, Jesus C. Hernández, Carlo Petrarca and Francisco Sanchez-Sutil

Electronics 2021, 10(2), 120; https://doi.org/10.3390/electronics10020120 - 8 Jan 2021

Cited by 16 | Viewed by 2847

Abstract

Photovoltaic (PV) systems are subject to nearby lightning strikes that can contribute to extremely high induced overvoltage transients. Recently, the authors introduced a 3D semi-analytical method to study the electromagnetic transients caused by these strikes in a PV module. In the present paper [...] Read more.

Photovoltaic (PV) systems are subject to nearby lightning strikes that can contribute to extremely high induced overvoltage transients. Recently, the authors introduced a 3D semi-analytical method to study the electromagnetic transients caused by these strikes in a PV module. In the present paper we develop an improved model of the PV module that: (a) takes into account high-frequency effects by modelling capacitive and inductive couplings; (b) considers the electrical insulation characteristics of the module; (c) includes the connection to a DC/DC converter. The whole process involves three major steps, i.e., the magnetic-field computation, the evaluation of both common-mode- and differential-mode-induced voltages across the PV module, and the use of the calculated voltages as input to a lumped equivalent circuit of the PV module connected to the DC/DC converter. In such a framework, the influence of the PV operating condition on the resulting electrical stresses is assessed; moreover, the relevance or insignificance of some parameters, such as the module insulation or the frame material, is demonstrated. Finally, results show that the induced overvoltage are highly dependent both on the grounding of the conducting parts and on the external conditions such as lightning current waveforms and lightning channel (LC) geometry. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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15 pages, 274 KiB

Open AccessFeature PaperArticle

Optimal Selection and Location of BESS Systems in Medium-Voltage Rural Distribution Networks for Minimizing Greenhouse Gas Emissions

by Oscar Danilo Montoya, Walter Gil-González and Jesus C. Hernández

Electronics 2020, 9(12), 2097; https://doi.org/10.3390/electronics9122097 - 9 Dec 2020

Cited by 8 | Viewed by 2977

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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15 pages, 323 KiB

Open AccessArticle

An Approach for Optimal Coordination of Over-Current Relays in Microgrids with Distributed Generation

by Sergio D. Saldarriaga-Zuluaga, Jesús M. López-Lezama and Nicolás Muñoz-Galeano

Electronics 2020, 9(10), 1740; https://doi.org/10.3390/electronics9101740 - 21 Oct 2020

Cited by 25 | Viewed by 2720

Abstract

The ever increasing presence of renewable distributed generation (DG) in microgrids is imposing new challenges in protection coordination. The high penetration of renewable DG enables microgrids to operate under different topologies, giving rise to bidirectional power flows and in consequence, rendering traditional coordination [...] Read more.

The ever increasing presence of renewable distributed generation (DG) in microgrids is imposing new challenges in protection coordination. The high penetration of renewable DG enables microgrids to operate under different topologies, giving rise to bidirectional power flows and in consequence, rendering traditional coordination approaches inappropriate to guarantee network security. This paper proposes an approach for the optimal coordination of directional over-current relays (OCRs) in microgrids that integrate renewable DG and feature several operational modes. As a main contribution, the characteristic curves of directional OCRs are considered to be decision variables, instead of fixing a single type of curve for all relays as considered in previous works. The proposed approach allows for the selection of several IEC and IEEE curves which combination results in the best protection coordination. Several tests were carried out on an IEC benchmark microgrid in order to show the applicability of the proposed approach. Furthermore, a comparison with other coordination approaches evidenced that the proposed approach is able to find lower operation times and, at the same time, guarantee the suitable operation of protections under different condition faults and operational modes. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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Review

Jump to: Research

25 pages, 710 KiB

Open AccessReview

A Review of Improvements in Power System Flexibility: Implementation, Operation and Economics

by Umar Taiwo Salman, Saifullah Shafiq, Fahad S. Al-Ismail and Muhammad Khalid

Electronics 2022, 11(4), 581; https://doi.org/10.3390/electronics11040581 - 15 Feb 2022

Cited by 16 | Viewed by 4868

Abstract

This study presents a literature review on the concept of power system flexibility in terms of its definition, indices, algorithms, implementation, economic impacts, operational impacts, and security. Although there are tremendous reviews on this subject in the literature, each paper discusses specific aspects [...] Read more.

This study presents a literature review on the concept of power system flexibility in terms of its definition, indices, algorithms, implementation, economic impacts, operational impacts, and security. Although there are tremendous reviews on this subject in the literature, each paper discusses specific aspects of flexibility. Moreover, the literature is devoid of a comprehensive review of the latest improvements in terms of implementation, operation, and economics, which are addressed by the collections presented in this study. This paper, therefore, surveys some improvements that have been made in recent decades. Furthermore, we highlight the impact of the high penetration of renewable energy and energy storage systems towards enhancing the improvement of power system flexibility. Full article

(This article belongs to the Special Issue Power System Simulation with Renewable Power: Protection, Optimization and Control)

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