Power-flow study

About: Power-flow study is a research topic. Over the lifetime, 8091 publications have been published within this topic receiving 155053 citations. The topic is also known as: load-flow study.

Distribution Network Reconfiguration Using Selective Firefly Algorithm and a Load Flow Analysis Criterion for Reducing the Search Space

Abstract: This paper proposes an alternative to solve the distribution network reconfiguration (DNR) problem, aiming real power losses' minimization. For being a problem that has 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 is compressed in a selective range of values. The algorithm is applied to the 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.

Power quality impact of grid-connected photovoltaic generation system in distribution networks

Abstract: In recent decades, the presence of photovoltaic (PV) systems is increased to provide power for local or remote loads However, when a large PV system connects to the distribution network under variable weather conditions, it may cause severe problems for power system components This paper presents a dynamic power quality analysis on a grid-connected PV system in a distribution system subjected to different weather conditions A 18 MW grid-connected PV system in a radial 16 bus test system is modelled and simulated under varying solar irradiations using the Matlab/Simulink software The simulation results proved that the presence of high penetrated grid-connected PV systems can cause power quality problems such as voltage rise, voltage flicker and power factor reduction

Newton Power Flow Methods for Unbalanced Three-Phase Distribution Networks

Abstract: Two mismatch functions (power or current) and three coordinates (polar, Cartesian andcomplex form) result in six versions of the Newton–Raphson method for the solution of powerflow problems. In this paper, five new versions of the Newton power flow method developed forsingle-phase problems in our previous paper are extended to three-phase power flow problems.Mathematical models of the load, load connection, transformer, and distributed generation (DG)are presented. A three-phase power flow formulation is described for both power and currentmismatch functions. Extended versions of the Newton power flow method are compared with thebackward-forward sweep-based algorithm. Furthermore, the convergence behavior for differentloading conditions,R/Xratios, and load models, is investigated by numerical experiments onbalanced and unbalanced distribution networks. On the basis of these experiments, we conclude thattwo versions using the current mismatch function in polar and Cartesian coordinates perform thebest for both balanced and unbalanced distribution networks.

Squirrel-Cage Induction Generator System Using Wavelet Petri Fuzzy Neural Network Control for Wind Power Applications

Abstract: A wavelet Petri fuzzy neural network (WPFNN) controller is proposed to control squirrel-cage induction generator (SCIG) system with an ac/dc power converter and a dc/ac power inverter for grid-connected wind power applications. First, the ac/dc power converter and the dc/ac power inverter are developed to deliver the electric power generated by a three-phase SCIG to power grid. Moreover, the ac/dc power converter and the dc/ac power inverter are mainly designed to control the mechanical rotor speed, dc-link voltage, and reactive power output of the SCIG system, respectively. Furthermore, since the varying active power outputs of the dc/ac power inverter seriously affect the tracking control of the dc-link voltage, a novel intelligent WPFNN controller is proposed to replace the traditional proportional-integral controller for the tracking control of the dc-link voltage in this study. In addition, the network structure and the online learning algorithm of the proposed WPFNN are described in detail. Finally, some experimental results are provided to show the effectiveness of the intelligent controlled-SCIG system using the proposed WPFNN controller for grid-connected wind power applications.