Flavio V. Gomes

Improvements in the representation of PV buses on three-phase distribution power flow

This letter describes a new voltage controlled bus (PV bus) representation in connection with the three-phase current injection method-TCIM of power flow analysis. This representation requires an augmented system of linearized equations to incorporate the reactive power as a dependent variable. Tests and comparisons between the former and the new approach are described and the improved stiffness of this new proposition is demonstrated.

Hybrid heuristic optimization approach for optimal Distributed Generation placement and sizing

This paper presents a hybrid algorithm that combines Particle Swarm Optimization (PSO) and Nonlinear Optimal Power Flow (OPF) in the optimal sitting and sizing of Distributed Generation (DG). The objective function considered is to minimize the power losses in distribution systems. The proposed approach makes use of a sensitivity index based on derivatives to identify the best candidate buses for sitting the DG. This index is considered in the PSO initial population aiming at reducing the search space, though, improving the convergence of the method. The OPF is then used to determine the optimal size of each DG. Results are compared with previous papers presenting different methodologies for the 69-bus radial distribution system to validate the proposed approach.

Capacitor placement to minimize active loss in distribution systems using bio-inspired optimization

This paper presents the development of a hybrid optimization model to minimize active losses in distribution systems through capacitor placement and sizing. The proposed model uses relaxed objective values obtained by a continuous non-linear optimization of the discrete variables as a base of comparison to the Ant Colony optimization model. The objective is to evaluate the model ability to present good solutions with a reduced number of individuals in the search process. A brief result is presented, demonstrating the gain of the proposed methodology when compared to other studies.

Reconfiguração de sistemas de distribuição utilizando fluxo de potência ótimo e análise de sensibilidade

This paper presents a new approach for distribution system reconfiguration (DSR) based on optimum power flow (OPF) in which the branch statuses (open/close) are represented by continuous functions. In the proposed approach, all branches are initially considered closed and from the OPF results a heuristic technique is used to determine the next loop to be broken by opening one switch. Then the list of switches that are candidates to be opened is updated and the above process is repeated until all loops are broken, making the distribution system radial. The paper includes results and comparisons on test systems utilized in three classical papers published in the technical literature, as well as in a previous paper by the authors. Results obtained on a real large scale distribution system are also presented.

Fluxo de carga em sistemas que apresentam linhas de potência natural elevada (LPNE)

This work presents an accurate approach for load flow calculation in electrical power systems in which high surge-impedance loading (HSIL) lines are present. The methodology consists in the use of three-phase power flow in phase coordinates for solving a sub-system where the unbalance effect due to HSIL lines are more accentuated. The traditional positive sequence load flow is used for the rest of the system. The proposed model has been validated in test systems.

Optimal restoration of power distribution system through particle swarm optimization

This paper proposes an approach for optimal restoration of radial power distribution networks after an incident. This complex problem requires a decision-making process whose combinatorial nature can avoid the assessment of all possible solutions. Thus, the proposed approach is based on a binary coding particle swarm optimization (PSO) tool for handling the discrete variables associated with the switching decisions. The restoration process involves a multi-objective reconfiguration model whose objectives are maximizing the supplied loads and the voltage regulation, with minimal power loss and switching maneuvers. Two case studies are introduced.

Power distribution systems planning with distributed thermal and wind generation

This paper presents a new approach for distribution systems planning with thermal and wind distributed generation (DG). This approach determines the optimal placement of biomass-based thermal and wind distributed generation aiming at minimizing the energy loss, emissions and the total investment and operation costs, as well as improving the voltage regulation. The costs for the purchased energy from grid and thermal generation based on biomass resource are considered. The wind power is given by pre-established nominal power and capacity factor. To solve the mixed integer nonlinear problem, a genetic algorithm (GA) with embedded optimal power flow (OPF) tool is proposed. The OPF is used to determine the size of the thermal generators. Results are presented for well-known systems from literature.