L. L. Pfitscher

Sensorless active yaw control for wind turbines

An active yaw control scheme for a horizontal axis wind turbine is proposed. The control strategy is based on measurement of the generated output power, without any wind intensity and/or wind direction sensors. Special attention is given to some control parameters to make the yaw driver less sensitive to wind turbulence. Results obtained in the laboratory implementation are presented and discussed in this paper.

Automatic Restoration of Power Supply in Distribution Systems by Computer-Aided Technologies

The need to improve quality and reliability of Power Systems has contributed to the advancement of research on Smart Grids and related topics. Some challenges that motivate the deployment of such researches include the increasing in energy consumption, environmental aspects, the integration of distributed and renewable generation, and new advances in computer aided technologies and automation. Smart Grids are characterized by a series of integrated technologies, methodologies and procedures for planning and operation of electrical networks. A survey of the main projects and researches related to Smart Grid is presented in (Brown, 2008).

Intelligent system for multivariables reconfiguration of distribution networks

This paper proposes a new distribution network reconfiguration approach in normal operating conditions. The multivariables are considered such as the energy losses minimization of the primary network and two reliability indices. The selection strategy of network configuration is based on a heuristic method. The method considers only the automated equipment such as switches and remote controlled reclosers in the new configuration analysis. The AHP (Analytic Hierarchic Process) method is used to define the weights for the optimization criteria and to determine the best switching sequence of the network reconfiguration. The reconfiguration is performed by monitoring the real time network. Changes in demand feeders are considered and analyzed by load rates. Also, the best setting for each operation level is defined. The results of the implemented techniques indicate a satisfactory methodology. Tests were performed using a real power utility system.

Studies on parallelism of feeders for automatic reconfiguration of distribution networks

The parallelism of distribution networks can be used to transfer loads between feeders without the need of disconnection of consumers during the maneuvers. In the context of the Smart Grids, the parallelism of feeders can be used in automatic reconfiguration of networks for the improvement of power quality and voltage levels, and reduction of energy losses. However, the maneuvers for parallelism must be preceded by studies to verify their technical and operational feasibility. This paper presents a study that discusses aspects of loading, protection, and voltage levels related to parallelism of networks, in transient and steady-state analysis. The validation of the developed methodology was carried out by comparison of simulation results with the ATP program. The study aims to be suitable for real-time application in reconfiguration of distribution networks. Integration with remote controlled switches, so that the network reconfiguration can be done automatically, is one of the differentials of the work. The tests here presented are made in a real model of a distribution network of a power utility. The developed algorithm has as main result a reliable indication of the technical feasibility of connecting feeders in parallel.

Automatic reconfiguration of distribution networks using Smart Grid concepts

Topological reconfiguration is an important tool for the planning and operation of electric power distribution systems. Usually, the utilities 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. Additionally, there is possibility to explore the automation equipment applying the concept of Smart Grid. This paper presents a new methodology and computer program for distribution network automatic reconfiguration. The topology is defined in real time and automatically performed by means of remote-controlled switches. The methodology includes a validation by computer simulations based on a multiple criteria decision making method. The developed tool has been applied in a pilot area of a power utility in Brazil.

Intelligent system for automatic reconfiguration of distribution networks

In Power Systems, the reconfiguration of distribution networks is used to reduce losses, to balance loads and to improve quality indicators. With the advances in Smart Grids and the increased use of remote controlled equipment, it becomes feasible to develop systems that allow the automatic reconfiguration of the network. This paper presents a system for automatic reconfiguration of distribution networks based on a heuristic method to determine the best network topology. The analysis of the feasibility of connecting feeders in parallel during the reconfiguration is discussed, focusing on transient and steady-state responses. The proposed methodology is under implementation and tests in a large real network and preliminary results are presented.

A tool for real time analysis of parallelism of distribution networks

The parallelism of distribution networks can be used to transfer loads between feeders without the need of disconnection of consumers during the switching. In the context of the Smart Grids, the parallelism of feeders can be used in automatic reconfiguration of networks for the improvement of power quality and voltage levels, and reduction of energy losses. However, the switching for parallelism must be preceded by studies to verify their technical and operational feasibility. This paper presents a study that discusses aspects of loading, protection, and voltage levels related to parallelism of networks, in transient and steady-state analysis. The validation of the developed methodology was carried out by comparison of simulation results with the ATP program. The study aims to be suitable for real-time application in reconfiguration of distribution networks. Integration with remote controlled switches, so that the network reconfiguration can be done automatically, is one of the differentials of the work. The tests here presented are made in a real model of a distribution network of a power utility. The developed algorithm has as main result a reliable indication of the technical feasibility of connecting feeders in parallel.

Experimental Platform for Operational Analysis of Distribution Networks

The benefits provided by changes of topology are essentials to better use of all electrical system elements. In some situations, it can be observed that the load transfer results in an instant decrease of losses along of network, providing the balancing of voltage levels, becoming the network more robust. Thus, this paper presents an analysis of the applicability of optimization methods of networks using an experimental platform, developed and tested in a controlled environment.

Reconfiguration of distribution network considering distributed generation and multivariables criteria

This paper presents a heuristic method to solve the network reconfiguration problem in the presence of distributed generation (DG) in order to minimize energy losses and improve the performance indexes in distribution system. Topological reconfiguration corresponds to an important tool for planning and operation of electric power distribution systems. Considering the distribution operation planning, how much time one algorithm gets an alternative topological status for the system is not a matter of importance, since the main objective assumed involves: power losses reduction, enhancing the voltage profile and increasing the reliability levels. In this challenge, multiple criteria might be used according to the utility purpose in observation of regulation policies and public awareness. Despite the complexity of this combinatorial issue in large systems, researchers are making an effort to find effective optimization methods since the classic ones do not represent a reasonable alternative.

Automatic restoration of power supply with possibility of islanded operation of distribution network

The continuity of electric energy supply to consumers is a permanent objective of the power utilities, pursuing the development of technological solutions to improve the performance of restoring power in contingency conditions. The main purpose is to minimize the impact on the number of consumers affected and reduce the time required to restore the energy supply. In this way, the power utilities have been employing efforts for the automation of distribution networks in order to restore power in a more agile way, resulting in better indexes of continuity and increase consumer satisfaction. Therefore, the purpose of this paper is to develop a methodology to restore the electric energy supply by using remote controlled switches, regarding the validation of the technical viability for distribution networks reconfiguration in real time by means of computational simulations. It is also considered the possibility of islanded operation of distribution networks. The best option for the load transfer using remote controlled switches, after contingencies, will be defined based on AHP (Analytic Hierarchical Process) method. The effectiveness of the proposed algorithm is demonstrated with case studies involving actual systems.