Lucas Frizera Encarnação

Optimal Placement of Distributed Generation Units in a Distribution System with Uncertain Topologies using Monte Carlo Simulation

Abstract In the literature, several papers propose new methodologies to determine the optimal placement/sizing of medium size Distributed Generation Units (DGs), using heuristic algorithms like Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). However, in all methodologies, the optimal placement solution is strongly dependent of network topologies. Therefore, a specific solution is valid only for a particular network topology. Furthermore, such methodologies does not consider the presence of small DGs, whose connection point cannot be defined by Distribution Network Operators (DNOs). In this paper it is proposed a new methodology to determine the optimal location of medium size DGs in a distribution system with uncertain topologies, considering the particular behavior of small DGs, using Monte Carlo Simulation.

DC-link regulation of a multilevel asymmetric cascaded D-STATCOM with staircase and discontinuous PWM modulation

Recently, problems related to poor energy quality, which in the last decade were responsible only for annoying situations and small losses in low voltage systems, are now causing damage to equipments and high financial losses to industries in medium voltage systems. The recent necessity of a better energy quality encourages the development of new specific custom power equipments directly connected in medium voltage systems. Therefore, several solutions were applied in order to enable the connection of custom power equipments in the medium voltage system, like as step down transformers and series connected semiconductors. However, it is well know that the multilevel converters are perfectly capable to work directly in the medium voltage systems and also presents several advantages when compared with others solutions. Although, some topologies, like the asymmetric cascaded multilevel converter, presents difficulties in regulating all the separated dc-link capacitors. In this context, this article presents a multilevel D-STATCOM with a proposed dc-link regulation control loop for generic cascaded multilevel converters to work directly in the medium voltage systems in order to improve the power quality in industrial installations. The performance of the multilevel D-STATCOM is presented by simulation and experimental results.

Study of combined cycle of Solid Oxide Fuel Cell with Micro Gas Turbines

Solid Oxide Fuel Cells (SOFC) present many advantages to generate electricity from natural gas, such as high efficiency, and little noise. However, the most important advantage of SOFC is its ability to operate at high temperatures. Their high operating temperature makes possible to use natural gas as fuel, so external hydrogen is not necessary for operation. In addition, in hybrid systems with cogeneration, the SOFC can be combined with micro gas turbine (MGT) to generate more power for the same amount of fuel. This cogeneration is interesting for power generation, from few kilowatts, for residences and commercial buildings, until megawatts as in plants for electric power generation, or industries. The study presented hear shows the increased efficiency when a MGT is integrated into the system to take advantage of exhaust gases of the SOFC.

Virtual Inertia for Power Converter Control

Abstract The integration of distributed generation units to the system has been emphasized in the last few years due to the increased use of renewable energy sources. The impact of the systems total inertia reduction that might increase frequency variations, affecting the systems stability when facing different types of disturbance, is an aspect to be analyzed. This chapter is dedicated to discuss the importance of the inertia for the system stability control. The traditional noninertial power control is compared with the inertial power control strategies. Moreover, a detailed explanation of the electric and mechanical models commonly used for the inertial power control strategies, including the exciter and governor equations, is presented and classified. To prove the efficiency of the inertial power control strategy for the frequency stability, a case study comparing the traditional noninertial and inertial power control strategies is presented and discussed.

Educational tool for radial electrical distribution networks analysis and optimization studies involving distributed generation units

The interest in optimization problems involving distributed generation units has grown among undergraduate and graduate students since distributed generation unit connections have been encouraged around the world, requiring efficient power system analysis tools to solve them. The available open access tools are commonly focused on transmission network analysis. On the other hand, commercial tools adapted to radial networks do not allow the students to follow the intermediary calculations and learn with them. In many cases, the students have to develop their own computational tools, which is a time-consuming activity. This paper aims to fill the gap encountered by undergraduate and graduate students when they are performing their optimization problems involving distributed generation units, presenting the advantages of a new power flow tool focused on radial electrical distribution networks with high levels of unbalanced loads which require a three-phase power flow tool to be analyzed. The use of the proposed tool allows the students focus on their research, reducing the time spent on programming, and learning about power flow analysis applied to radial networks.

New sequence voltage detector for Distributed Generation with high-harmonic distortion using Fourier Linear Combiner

This paper presents a positive negative and zero sequence detector for Distributed Generation with high harmonic distortion. This detector, named Sequence Detector Fourier Linear Combiner (SDFLC) uses a modification of Fourier Linear Combiner and Fortescue Transform to instantaneously estimate the amplitude, phase and frequency of all phase and all components from a three-phase signal. The SDFLC demonstrate a robust and reliable algorithm to detect high harmonic problems. In this paper, its structure was completely presented and tested to a sort of detection problems.

Analysis of contribution from solar generators for short circuit in an urban distribution system

The current distribution systems and power transmission are designed with a power flow characteristic flowing from the source to the load at all times. From the dissemination and use in larger-scale distributed generators, questions arise as to the operation of current protection systems. This article aims to analyze the contribution to the short circuit of a solar generator connected to an urban power grid, to support an analysis of the cur — action of the protections currently installed, they do not consider the installation of new generators coming to consumers.

Technical review of protection settings considering the influence of distributed generation

Several countries are encouraging the installation of distributed generation units with great success. The connection of these units to the existing electrical system gives rise to new challenges relating to the operation of the electrical system and operation of the protection. Thus, several recent studies suggest techniques to define the best protection settings to ensure coordination and selectivity of the protection system. This article will present the biggest problems that arise with the connection of distributed generation units to the electrical system, and will also present the state of the art techniques used to change the settings of the protections aimed at accommodating the changes that distribuited generation require to the electric system operation.

Distributed Generation Units as Ancillary Services Providers in a Pre Smart Grid Environment

Abstract Nowadays, ancillary services in electrical distribution networks (e. g. voltage support and reactive power control), usually provided by capacitor banks, start to be performed by distributed generation units (DGs). In this way, several papers have been studying the use of DGs as reactive power providers, and the power electronic/market regulation involved in this new scenario. However, the authors commonly consider a full implementation of Smart Grid philosophy, i. e., there are appropriate communications between DGs and distribution network operator (DNO)’s control centers, but it is not a close reality in many developing countries, due to high costs involved in their implementation. Therefore, this paper proposes a new method in order to use DGs as ancillary services providers in a short and medium-term (called in the literature Pre Smart Grid), in which there are not effective communications between DGs and control centers of DNOs. The proposed method uses a non-uniform DGs distribution, obtained from local atlas of wind, solar, hydraulic and biomass power. The methodology presented accurate results when compared with a PSO-based method, widely used to solve optimization problems, but needs a complete Smart Grid philosophy implementation to work.

Distribution networks automatic generation tool to perform statistical validations of technical planning methodologies

There is a lack of rigor in the validation process of technical planning methodologies. In general, such methodologies are tested only in one or two different case studies. Therefore, this paper proposes the creation of a tool that automatically generates feasible distribution networks in order to perform statistical validations of technical planning methodologies. Using a statistical approach through a linear random distribution and a GUI (graphical user interface) built at MATLAB, the developed tool can create feasible networks with the characteristics desired by the user, such as network length, number of branches and types of loads. The developed tool generates text output files that include all characteristics and are formatted according to a defined pattern. This tool can lead to future improvements in many areas, such as the implementation of the Smart Grid philosophy.