Luciane Neves Canha

An electrochemical-based fuel-cell model suitable for electrical engineering automation approach

This paper presents a dynamic electrochemical model for representation, simulation, and evaluation of performance of small size generation systems emphasizing particularly proton exchange membrane fuel-cell (PEMFC) stacks. The results of the model are used to predict the output voltage, efficiency, and power of FCs as a function of the actual load current and of the constructive and operational parameters of the cells. Partial and total load insertion and rejection tests were accomplished to evaluate the dynamic response of the studied models. The results guarantee a better analytical performance of these models with respect to former ones with a consequent reduction in time and costs of projects using FCs as the primary source of energy. Additionally, this electrochemical model was tested for the SR-12 Modular PEM Generator, a stack rated at 500 W, manufactured by Avista Laboratories, for the Ballard Mark V FC and for the BCS 500-W stack.

Multicriteria Distribution Network Reconfiguration Considering Subtransmission Analysis

Topological reconfiguration is an important tool for the planning and operation of electric power distribution systems. The amount of time that an algorithm spends on obtaining an alternative topological status for the system is not a primary concern, since the main goals of distribution operation planning are the reduction of power losses, the enhancement of the voltage profile, and the increase of reliability levels. The utility can use multiple criteria regarding the observation of regulation policies and public awareness to drive the topological reconfiguration. Several researchers are looking for new optimization methods, as the complexity of this combinatorial issue is high in large systems and the classic optimization methods are failing to address the problem reasonably. Therefore, we propose a new fuzzy multicriteria decision making algorithm and software to distribution network reconfiguration also including the power losses analysis of subtransmission systems. The effectiveness of the proposed algorithm is demonstrated with case studies involving actual systems.

AHP Decision-Making Algorithm to Allocate Remotely Controlled Switches in Distribution Networks

Continuity in power supply for the consumers is a permanent concern from the utilities, pursued with the development of technological solutions in order to improve the performance of network restoration conditions. Using remotely controlled switches corresponds to one possible approach to reach such an improvement and gives some convenient remote resources, such as the fault detect, isolation, and transfer loads. This paper presents a methodology implemented in a computer programming language for allocation of these devices in electric distribution systems based on the analytic hierarchical process (AHP) method. The main contributions focus on considering the impact of installing remotely controlled switches in the reliability indices and the AHP decision-making algorithm for the switches allocation. The effectiveness of the proposed algorithm is demonstrated with case studies involving actual systems of the AES Sul utility located in Southern Brazil.

An analysis of the dynamic performance of proton exchange membrane fuel cells using an electrochemical model

This paper presents a dynamic electrochemical model for representation, simulation and evaluation of the performance of small size generation systems using PEM fuel cells. The results of the model are used to predict the output voltage, efficiency and power of the fuel cell as a function of the actual load current and of the constructive and operational parameters of the cells. Partial and total load insertion and rejection tests were accomplished to evaluate the dynamic response of the studied models. The results guarantee a better analytical performance of these models with the consequent reduction of time and costs of projects using fuel cells as a primary source of energy.

Multicriteria decision making for management of storage energy technologies on renewable hybrid systems - the analytic hierarchy process and the fuzzy logic

Worldwide, several studies have investigated many proposals for the use of hybrid systems as alternative energy sources, operating together with energy storage technologies. Accordingly, there are large concerns about the use of appropriate methods to evaluate the application of renewable energy sources and storage energy systems. Thus, it is important to observe that the renewable hybrid systems are environmental friendly, having as consequence governmental incentives for their development in many countries, like Brazil. This paper presents a methodology taking as basis the theory developed by Saaty -- the Analytic Hierarchy Process (AHP method) - and multi-rulesbased decision and multi-sets considerations applied using fuzzy logic. By exploiting a multi-criteria decision making, this methodology evaluates the operation of storage energy systems such as: compressed air energy storage (CAES), pumped hydro storage (PHS), H2 storage, flywheel and super-capacitors. In addition, different scenarios are investigated concerning environment impacts and costs. For the purpose of the study, these five different energy storage technologies are evaluated objectifying to find the most appropriate storage energy system for different scenarios, always considering the desirable criteria, namely: efficiency, costs, technical maturity, environmental impacts, power application range and lifecycle.

Selection of storage energy technologies in a power quality scenario — the AHP and the fuzzy logic

In response to the escalating energy crisis and related pollution problems verified worldwide, it is essential to assume new energy technologies that use renewable energy sources in an efficient and environmentally friendly manner. However, widespread implementation of these sources will be more attractive only if they operate together with energy storage technologies. Besides, a successful storage energy selection is essential to deal with some mismatches among costs, efficiency and power quality constrains. This paper presents a methodology taking as basis the AHP (Analytic Hierarchy Process) and fuzzy logic. By exploiting a multi-criteria decision making, this methodology evaluates the operation of storage energy systems such as: pumped hydro storage (PHS), compressed air energy storage (CAES), H2 storage, flywheel and super-capacitors. The main objective of the study is to develop a multicriteria analysis to find the most appropriate storage energy system concerning a power quality scenario. For this, the criteria in analysis are: efficiency, load management, technical maturity, costs, lifecycle and power quality. Considerations and results described in this paper are part of the Research & Development Program undertaken by the Federal University of Santa Maria, Brazil.

Methodology for placement of Dispersed Generation Systems by analyzing its Impacts in Distribution Networks

The Brazilian electric systems need the development of new researches and tools, in order to obtain a logic solution to maintain and improve the reliability and the quality of the power delivered to customers. The study of the appropriate connection of dispersed generation sources is an essential topic to be analyzed, since this process may provide positive impacts along the feeders. The main effects of the DG operation inside a distribution system model are here analyzed through the software DigSilent®, considering power losses and voltage levels. Moreover, a multi-objective methodology - Bellman-Zadeh algorithm and membership fuzzy functions - is used for evaluating quantitative and qualitative parameters. The main objective of the paper is finding the appropriate DG placement inside a distribution system model. It is important to observe that the methodology presented in this study can be applied to distribution system feeders to find in which feeder will be the most appropriate DG location, as well to any node inside a determined feeder providing a specific place for the appropriate DG site.

Software for Automatic Coordination of Protection Devices in Distribution System

Among the several components of distribution systems, protection devices present a fundamental importance, since they aim at keeping the physical integrity not only of the system equipment, but also of the electricians team and the population in general. The existing tools today in the market that carry out the making of protection studies basically draw curves, and need direct users interference for the protection devices adjustment and coordination analyses of selectivity, being susceptible to the users mistakes and not always considering the best technical and economical application. In Brazil, the correct application of the protection devices demand a high amount of time, being extremely laborious due to the great number of devices (around 200 devices), besides the very dynamic behavior of distribution networks and the need for constant system expansion. This paper presents a computational tool developed with the objective of automatically determining the adjustments of all protection devices in the distribution networks to obtain the best technical application, optimizing its performance and making easier protection studies.

Algorithm of reliability optimization for operational planning of distribution systems

Reliability of energy supplies is considered the most important technical and economical characteristic of an electric system. The most efficient solution to increase the reliability in distribution systems, in most cases, is the rational sectioning of the networks. In that direction, the main difficulty in the formation of mathematical optimization models of reliability is the growing complexity of analytical expressions for definition of indicators to represent the system reliability. In this paper, is analyzed an approach to allow construction of objective functions and restrictions containing discreet variables, considering a set of factors such as: statistical data of faults, topology and parameters of the networks, location and characteristics of commutation equipments, etc. However, an attempt to use exact methods of discreet optimization causes an increase in the number of variables and restrictions and, as a consequence, presents insuperable computing difficulties. Therefore, it is proposed and tested a heuristic method of optimization to overcoming such difficulties.

Storage energy management with power quality concerns the analytic hierarchy process and the fuzzy logic

In view of current and foreseeable energy shortage and environmental scenario, the exploitation of renewable energy sources offer great potential to satisfy the energy lack and to decrease the dependence on fossil fuel, also reducing global warming caused by CO2 emissions. However, widespread implementation of these sources will be more attractive only if they operate together with energy storage technologies. Besides, an effective storage energy management is essential to deal with some mismatches among power quality, efficiency, costs and environmental constrains. This paper presents a methodology taking as basis the analytic hierarchy process and fuzzy multi-rules and multi-sets. By exploiting a multi-criteria decision making, this methodology evaluates the operation of energy storage systems such as: pumped hydro storage (PHS), compressed air energy storage (CAES), H2 storage, flywheel, super-capacitors, lithium-ion and NaS advanced batteries and VRB flow battery. The main objective of the study is to develop a multicriteria analysis to find the most appropriate energy storage system concerning a power quality priority. For this, the criteria in analysis are: efficiency, load management, technical maturity, costs, environment impacts and power quality. Considerations and results described in this paper are part of the Research & Development Program undertaken by the Federal University of Santa Maria, Brazil.