Rubén Romero

São Paulo State University | Unesp · Department of Electrical Engineering

Metaheuristic optimization algorithms are increasingly used to reach near-optimal solutions for complex and large-scale problems that cannot be solved in due time by exact methods. Metaheuristics’ performance is, however, deeply dependent on their effective configuration and fine-tuning to align the algorithm’s search process with the specific char...

This paper presents a variable neighborhood descent (VND) algorithm for the service restoration problem (SRP) in distribution systems. The restoration problem appears when a permanent fault occurs in the system. The fault must be localized and isolated from the rest of the system. As a consequence of the isolation, the downstream area is de-energiz...

The economic interest in power loss minimization and regulatory requirements regarding voltage levels in distribution systems are considered. In this paper, a computational technique to assist in the optimization of the power losses and voltage characteristic in the steady state through distribution network reconfiguration and the location and size...

This paper presents a novel scenario-based stochastic mixed-integer second-order cone programming model to solve the problem of optimal reconfiguration of distribution systems with renewable energy sources considering short-circuit constraints. The proposed formulation minimizes technical losses by modifying the statuses of sectionalizing and tie s...

The firefly algorithm (FA) and the artificial bee colony (ABC) algorithm are used in this study to perform a coordinated parametrization of the proportional-integral and supplementary damping controllers, i.e., power system stabilizers (PSSs) and the unified power flow controller (UPFC)–power oscillation damping set. The parametrization obtained fo...

Complex optimization problems are often associated to large search spaces and consequent prohibitive execution times in finding the optimal results. This is especially relevant when dealing with dynamic real problems, such as those in the field of power and energy systems. Solving this type of problems requires new models that are able to find near...

This article presents a novel mixed-integer second-order cone programming model to increase the photovoltaic (PV) hosting capacity and optimize the operation of distribution networks. The problem considers voltage and reactive (Volt/VAr) control through the optimal operation of capacitors banks, substations’ on-load tap changers, voltage regulators...

In this paper, it is proposed to apply the mayfly optimization algorithm (MOA) to perform the coordinated and simultaneous tuning of the parameters of supplementary damping controllers, i.e., power system stabilizer (PSS) and power oscillation damping (POD), that actuate together with the automatic voltage regulators of the synchronous generators a...

The branch and bound (BB) algorithm is widely used to obtain the global solution of mixed-integer linear programming (MILP) problems. On the other hand, when the traditional BB structure is directly used to solve nonconvex mixed-integer nonlinear programming (MINLP) problems, it becomes ineffective, mainly due to the nonlinearity and nonconvexity o...

This paper presents a new mixed-integer linear programming model for the optimal restoration of active distribution networks during permanent fault events considering not only network reconfiguration but also the islanded operation of distributed generation, thereby giving rise to the formation of microgrids. To that end, the proposed approach acco...

This work presents a strategy, from the perspective of the distribution system operator (DSO), that aims at simultaneously estimating the maximum penetration levels of renewable-based distributed generation (DG) and electric vehicles (EVs) that can be accommodated into an electric distribution system (EDS). To estimate such capacity, operational re...

The electric vehicles (EVs) are flexible loads that can be controlled to provide secondary reserve services (RSs) to transmission network operator (TNO) via charging or stop charging the batteries. An aggregator, as an intermediary agent between the EVs owners and the TNO, can schedule RSs through EV charging control. This paper proposes a smart ag...

This paper presents a new stochastic mixed-integer second-order cone programming model to solve the problem of optimal operation of distribution systems considering network reconfiguration, voltage control devices, dispatchable and nondispatchable distributed generators (DGs), and the possibility of closed-loop topology operation. The decision vari...

The growing trend of electric vehicles (EVs) and building integrated photovoltaics (BIPVs) is a promising means to reduce related climate change issues. EV loads can be managed via an aggregator to maximize the usage of green energy produced by photovoltaic units (PV) through smart charging strategies that exploit controllable EV demand connected t...

For a few decades, researchers try to reach a better solution by proposing new models or methods for distribution system reconfiguration (DSR) problem. This paper presents an efficient model for reconfiguration of radial distribution systems, aiming loss minimization. The proposed model can be easily solved by every commercial solvers and software....

This article presents a new mathematical model to solve the restoration problem in balanced distribution systems with distributed generators (DGs) considering closed-loop topology operation during the restorative state. The restorative state is comprised of the interval of time since the permanent fault has been isolated until the time at which the...

..is paper presents a new mixed-integer second-order cone programming model for solving the restoration problem in active distribution systems considering the optimal control of distributed generators (DGs), voltage regulators (VRs), on-load tap changers (OLTCs), and capacitor banks (CBs). In contrast to most of the works found in the literature, t...

The implementation of local electricity markets (LEMs) requires efficient tools that can provide solutions for the optimal management of distributed energy resources (DERs) considering economic and technical aspects. This chapter presents mathematical models for the formulation of optimization problems in LEMs including DERs (renewable distributed...

A restoration problem in a radial electrical distribution system (EDS) is solved to restore de-energized loads downstream of sectors affected by a permanent fault, transferring loads among primary feeders through switching operations. As it is a computationally complex problem, its resolution by exact optimization techniques in a treatable runtime...

Neste trabalho é apresentada uma estratégia heurística para resolver o problema de reconfiguração de alimentadores da rede primária de sistemas de distribuição de energia elétrica radiais. A estratégia está inspirada em conhecimento relativamente recente que permite identificar todas as topologias radiais existentes em um sistema de distribuição. E...

This paper presents a new mixed-integer linear programming model for the optimal restoration of active distribution networks during permanent fault events considering not only network reconfiguration but also the islanded operation of distributed generation, thereby giving rise to the formation of microgrids. To that end, the proposed approach acco...

This paper proposes a decimal codification genetic algorithm to solve the transmission network expansion planning (TNEP) problem considering the economic impact of line maintenance. The goal is to extend the lifespan of the time-worn lines in order to reduce the investment cost in the expansion of the transmission network and to improve the worth o...

Transportation electrification plays an important role in developing more sustainable systems. As a result, the adoption of electric vehicles (EVs) is increasingly endorsed by governmental policies. It can be even more encouraged by promoting the provision of different ancillary services using vehicle-to-grid (V2G) enabled EVs, since EV owners may...

Este artigo apresenta um novo método para resolver o problema de reconfiguração de sistemas de distribuição de energia elétrica com a alocação simultânea de geradores distribuídos. É proposta uma meta-heurística baseada no algoritmo de busca em vizinhança variável (VNS) que realiza a reconfiguração do sistema e alocação de geradores distribuídos e...

In this article, the optimal transmission switching (OTS) problem is solved in order to optimize the operation cost of an electrical power system. This is accomplished by disconnecting some transmission lines, which enables a change to the profile of the power flow distribution in the system, allowing for increased generation at the buses with lowe...

Commonly, in the transmission network expansion planning (TNEP) problem, the objective is to define the minimal-cost investment in new transmission devices, e.g., the transmission lines and transformers, for the system to operate adequately in a planning horizon. In addition to the traditional approach of considering the installation of new compone...

The integration of distributed energy resources (DERs), e.g., electric vehicles (EVs) and renewable distributed generation (DG), in the electrical distribution system (EDS) brings advantages to society, but also introduces technical challenges (e.g., overloading and voltage issues). A DER aggregator, which has agreements with DERs to manage their c...

One of the approaches to represent competitive market rules, uncertainties in the generation, and different seasonal climatic conditions in the multistage transmission network expansion planning problem is through scenario-based modeling, by considering several generation scenarios. However, the investment costs of the solutions obtained by this ty...

This paper presents a reformulated algorithm based on the Tabu Search meta-heuristic to simultaneously solve the problem of reconfiguration and optimal allocation of fixed capacitor banks in electric power distribution systems. In the formulation, strategies were developed to generate the initial solution using the Prim algorithm and a heuristic to...

This paper presents a biased random-key genetic algorithm applied to the problem of optimal allocation of capacitor banks in radial electric power distribution systems. It is intended to minimize the investment and operating costs of the distribution system considering several levels of demand and an annual operating horizon. The proposed algorithm...

Power systems must be prepared to match the current growing demand for electrical energy. In this paper, the transmission network plays an important role, delivering the electric power generated in conventional power plants to load centers. For the last 45 years, the transmission network expansion planning (TNEP) problem has been widely studied; no...

The electrical grid is undergoing an unprecedented evolution driven mainly by the adoption of smart grid technologies. The high penetration of distributed energy resources, including renewables and electric vehicles, promises several benefits to the different market actors and consumers, but at the same time imposes grid integration challenges that...

Maintenance in transmission networks is an economical way to reduce upgrading network costs without decreasing its reliability. Hence, new studies regarding transmission expansion planning (TEP) must take into account the effects of maintenance in order to obtain realistic and economic expansion investment plans. This work presents a novel framewor...

Transmission network expansion planning (TNEP) is subject to several constraints that are driven by new market rules, such as generation uncertainty, demand growth, seasonal climate changes and technological advances. When considering multiple generation scenarios, due to different operational conditions, it is necessary to find an expansion plan t...

This paper presents a study about operation planning for radial distribution systems using a mixed-integer second-order cone programming formulation. The proposal consists of a complete model for solving the pro- blems of the reconfiguration of feeders and allocation of capacitor banks simultaneously, with the objective of achieving a minimum overa...

Trend-setting countries have promoted or even employed an increased number of electric vehicles (EVs) and other distributed energy resources (DERs) in their power systems. This development has triggered new and increasing challenges in the distribution system planning and operation, whereby the distribution systems must adapt to the increased share...

This paper presents a new formulation for loss minimization in distribution network reconfiguration problem. The proposed model can be easily solved by every comerical solvers and software. The proposed formulation was tested on 16-bus distribution test system and Taiwan power company (TPC) network. Simulation results show high efficiency of the pr...

Maintenance in transmission networks is an economical way to reduce upgrading network costs without decreasing its reliability. Hence, new studies regarding transmission expansion planning (TEP) must take into account the effects of maintenance in order to obtain realistic and economic expansion investment plans. This work presents a novel framewor...

The growing penetration of low-carbon technologies in residential networks such as photovoltaic generation (PV) units and electric vehicles (EVs) may cause technical issues on the grid. Thus, operation planning of electrical distribution networks (EDNs) should consider the inclusion of these technologies in order to avoid operational limit breaches...

This paper evaluates the economic and reliability effects of line maintenance on generation and transmission expansion planning (GTEP), considering line loading and repair. The aim is to make a balance among the expansion and operation costs, generation and transmission system reliability, lines loading, and maintenance and repair cost of transmiss...

This paper studies maintenance effect on transmission network expansion planning (TNEP) problem. The main goal is to decrease the total transmission network expansion cost by increasing transmission system worth through the relationship between maintenance and lifetime of transmission lines. For this purpose, the effect of the lifetime of transmiss...

his paper studies maintenance effect on transmission network expansion planning (TNEP) problem. The main goal is to decrease the total transmission network expansion cost by increasing transmission system worth through the relationship between maintenance and lifetime of transmission lines. For this purpose, the effect of the lifetime of transmissi...

Optimal reconfiguration is one of the most important strategies used to improve the operation of radially operated distribution systems. A large amount of research related to the reconfiguration problem has been carried out. Nevertheless, some topics still need to be discussed in order to provide guidance for future research related to the reconfig...

Stationary energy storage systems (ESSs) are becoming a prominent option to support the power grid via ancillary services. For instance, transmission system operators (TSOs) can take advantage of the fast control capabilities of stationary ESSs to implement primary frequency regulation. However, capital costs are directly related to the battery ene...

The transmission network expansion planning problem is traditionally solved considering only a single generation scenario. However, due to new market rules, uncertainties in the generation, and different seasonal climatic conditions, the traditional model for this type of problem can generate solutions that are not suitable for the operation of the...

This paper presents an optimization algorithm that performs the integrated optimization of the reconfiguration and allocation of capacitor banks in radial distribution systems using a multi-start metaheuristic. The objective is to find an optimal operating strategy that minimizes the operating costs of the system over a chosen horizon. Thus, the co...

This paper presents a specialized Greedy Randomized Adaptive Search Procedure (GRASP) algorithm to solve the problem of reconfiguration of radial electric power distribution systems. The objective is to find the radial operating topology that minimizes the active losses in the system and that complies with the natural laws of circuits (both Kirchho...

Smart Grid schemes in which multiple network elements and participants are managed for the benefit of the distribution network (e.g., energy loss reduction, restoration, etc.) require sophisticated algorithms to control them in the most suitable manner while catering for network constraints. Such a complex decision making process can be solved by t...

This paper presents a mixed integer linear programming (MILP) model to optimize the costs of maintenance and extra hours for scheduling a fleet of battery electric vehicles (BEVs) so that the products are delivered to prespecified delivery points along a route. On this route, each BEV must have an efficient charging strategy at the prespecified cha...

This paper presents a mixed-integer second order cone programming model for the problem of optimal distribution systems expansion planning for improving service restoration. The objective is to obtain a network that allows the load to be restored after the occurrence of a contingency. Expansion of new substations, reinforcement of existing ones, ad...

Este artigo apresenta o método da Busca Dispersa aplicado na otimização de funções numéricas contínuas multimodais com restrições. O método da Busca Dispersa é uma meta-heurística que se difere de outros algoritmos evolutivos, pois utiliza estratégias diferentes da aleatoriedade para explorar o espaço de busca do problema. Um algoritmo baseado em s...

Smart Grid schemes in which multiple network elements and participants are managed for the benefit of the distribution network (e.g., energy loss reduction, restoration, etc.) require sophisticated algorithms to control them in the most suitable manner while catering for network constraints. Such a complex decision making process can be solved by t...

Energy storage systems are lauded solutions for integrating the ever-increasing amounts of renewable energy sources in distribution networks. Electrochemical batteries, principally lithium-ion based, are among the most promising storage technologies for these applications due their high energy densities, capacities, and efficiencies. The operation...

This study investigates the economic and reliability effects of line maintenance on composite transmission and generation expansion planning, considering the reliability of transmission and generation systems. The aim is to find a compromise among the expansion costs of the transmission and generation systems, power system reliability, and the main...

Electric distribution networks should be prepared to provide an economic and reliable service to all customers, as well as to integrate technologies related to distributed generation, energy storage, and plug-in electric vehicles. A proper representation of the electric distribution network operation, taking into account smart grid technologies, is...

Nowadays, several test systems available in the specialized literature are used to verify studies regarding power system planning or network reliability. However, there are no test systems currently available with enough information in order to endorse studies that simultaneously approach expansion planning, operation, and reliability issues. This...

This paper presents a variable neighborhood search (VNS) optimization algorithm for the design of the parameters of supplementary damping controllers: power system stabilizers (PSS) and the interline power flow controller–power oscillation damping (IPFC–POD) set. The objective is to insert damping to local and inter-area oscillation modes in multim...

This paper proposes a relaxed mathematical model to solve the restoration problem of radial and balanced electrical distribution systems. The mathematical model is a mixed-integer linear programming formulation that can be efficiently solved by commercial solvers. After a restoration problem is solved using this model, the quality and feasibility o...

This paper proposes a new method to solve the multistage security-constrained transmission expansion planning problem, incorporating lines based on high-voltage alternating current (HVAC) and high-voltage direct current (HVDC) alternatives. A novel mixed-integer linear programming model, which incorporates transmission losses using a piecewise line...

Transmission network expansion planning (TNEP) is an important issue in power system planning which must have optimal performance besides technical constraints. This paper presents a new framework for transmission network expansion planning (TNEP) based on reliability criteria. The aim is to compromise between transmission lines expansion and load...

This paper presents a multi-start optimization algorithm that performs the simultaneous reconfiguration of feeders and allocation of capacitor banks in radial distribution systems. The objective is to find an optimal operating topology for the system together with an optimal plan of investment and operation for capacitor banks that minimizes the op...

The aim of this paper is to investigate maintenance effects on system reliability and transmission network expansion planning (TNEP) considering line loading and repairs. For this purpose, the maintenance cost is formulated taking into account transient and permanent forced outage rates, as well as durations of planned and forced outage. Also, tran...

This paper presents a methodology to solve the long-term transmission expansion planning problem incorporating angular cuts based on the constraints impose by circuits with low capacity-reactance product over other circuits with high capacity-reactance product in parallel with them. These cuts aim to reduce the search space of the problem and the t...

This paper presents a mixed-integer non-linear programming (MINLP) model for the optimal restoration/ maintenance switching sequence of unbalanced three-phase electrical distribution systems. Once the protection coordination has identified and cleared a faulty zone, the proposed MINLP model determines the status of remotely controlled switches and...