This paper proposes an alternative to solve the distribution network reconfiguration (DNR) problem aiming real power losses minimization. For being a problem that has a complexity for its solution, approximate techniques are adequate for solving it. Here, the proposition is a technique based on the firefly metaheuristic, named selective firefly algorithm, where the positioning of these insects are compressed in a selective range of values. The algorithm is applied on DNR, and all its implementation and adequacy to the problem studied are presented. To define the search space, the methodology presented initially considers a set of candidate switches for opening based on the studied systems mesh analysis. To reduce these possibilities, a refinement through a load flow analysis criterion (LFAC) is proposed. This LFAC considers the real power losses on each branch for a configuration with all switches closed, then, selecting possible switches to elimination from the set previously established. To demonstrate the behavior and the viability of the LFAC, it was initially applied on a 5 buses and 7 branches system. Also, to avoid getting stuck on results that may be considered not good, a disturbance resetting the population is set to occur every time a counter reaches a pre-defined number of times that the best solution does not change. Results found for simulations with 33, 70, and 84 buses are presented and comparisons with selective particle swarm optimization (SPSO) and selective bat algorithm (SBAT) are made.

Virtual power plant (VPP) interconnects distributed generation (DG) units, microgrids, and energy storage systems (ESSs) of an electrical power system. This paper presents a linear programming cost minimization model of VPP for the design and commitments of DG, ESS, and microgrid. Using a set of renewable energy resources, the proposed model creates a reliable, cost-effective, and environmentally friendly distribution system. Accurately, it illustrates the schedule of the VPP to operate autonomously. The proposed model is applied to a set of United States commercial load profiles to determine the investment benefit of implementing DGs in the power system. Analysis of results concerning variation in energy price illustrates feasible solutions. VPP decision-makers can select the best reasonable solution based on their specific project budget for feature electricity generation. Moreover, results show the need for the proposed method in VPP decision making.

This paper proposes a robust finite control set for DFIG power control. In this way, the proposed robust finite control has two components of the predicted rotor voltage. The first term calculates the voltage considering the rotor current references and the second term is designed considering the mistakes due to parameters estimation. The mentioned errors due to parameters variations were modeled as rotor current changes. Hence, the controller calculates the predicted rotor voltage considering parameter variations and rotor current references. So that, the minimized cost function selects the voltage vector to be supplied to the rotor of the machine. The influence of the estimation errors for variations on R2 and σL2 was also investigated. The results obtained in a setup confirm the controller performance.

An estimation procedure for transmission line parameters is developed that combines a new method of determining line parameters with others available in the technical literature. Each estimation method has certain advantages and restrictions that depend on the operating conditions of the transmission system (e.g. the load profile), the physical characteristics of the line (e.g. the length and the geometry) and electromagnetic phenomena (e.g. single‐ or multiphase faults). The proposed estimation procedure exploits the major attributes of both the new determination method developed in this study and other well‐established methods previously presented in the technical literature. Based on current and voltage measurements obtained from synchronised fault records from both line terminals, a combination of multiple methods can be used to accurately estimate most line parameters, a task that is typically impossible using a single method.

This paper presents a hybrid way mixing time and frequency domain for transmission lines modelling. The proposed methodology handles steady fundamental signal mixed with fast and slow transients, including impulsive and oscillatory behaviour. A transmission line model is developed based on lumped elements representation and state-space techniques. The proposed methodology represents an easy and practical procedure to model a three-phase transmission line directly in time domain, without the explicit use of inverse transforms. The proposed methodology takes into account the frequency-dependent parameters of the line, considering the soil and skin effects. In order to include this effect in the state matrices, a fitting method is applied. Furthermore the accuracy of proposed the developed model is verified, in frequency domain, by a simple methodology based on line distributed parameters and transfer function related to the input/output signals of the lumped parameters representation. In addition, this article proposes the use of a fast and robust analytic integration procedure to solve the state equations, enabling transient and steady-state simulations. The results are compared with those obtained by the commercial software Microtran (EMTP), taking into account a three-phase transmission line, typical in the Brazilian transmission system.