Topic
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.
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09 Jun 2013
TL;DR: In this paper, the authors proposed four typical control architectures for DC micro-grid: droop control, hierarchical control, fuzzy control, and multi-agent based control architecture, and discussed the energy storage system with an optimized strategy is able to keep balance of power supply, ensure system reliability and improve power quality.
Abstract: Compared with AC micro-grid, DC microgrid obtains some advantages and are more suitable for the access of distributed power sources. The DC Bus voltage of DC micro-grid should be regulated to avoid a circular current with proper control strategies. There are four typical control architecture presented in this paper: droop control architecture, hierarchical control architecture, fuzzy control architecture and multi-agent based control architecture. Energy storage is very important to ensure normal operation of DC micro-grid. An energy storage system with an optimized strategy is able to keep balance of power supply, ensure system reliability and improve power quality, which is also discussed in this paper.
42 citations
22 Oct 2012
TL;DR: In this article, an economic dispatch problem for unbalanced three-phase power distribution networks with distributed generation (DG) units is considered, and a semidefinite relaxation technique is advocated to obtain a relaxed convex problem solvable in polynomial-time complexity.
Abstract: The papers considers an economic dispatch problem for unbalanced three-phase power distribution networks with distributed generation (DG) units. The objective is to minimize the overall active power supplied by the DG units and drawn from the substation, subject to constraints on the voltage magnitudes at the nodes, and on the power factor (PF) at the substation. The latter constraint is also applied to nodes equipped with capacitor banks. Similar to its optimal power flow counterparts for balanced systems, the formulated optimization problem is nonconvex. Nevertheless, a semidefinite relaxation technique is advocated to obtain a relaxed convex problem solvable in polynomial-time complexity. Numerical tests on the IEEE 13-node test feeder demonstrate the ability of the proposed method to attain the globally optimal solution of the original nonconvex problem.
42 citations
TL;DR: In this paper, a method for reenergizing large portions of a blacked out electric power system with a minimum of switching and thus time to restoration is described, and results of a simulated system restart utilizing actual power system facilities are compared to power flow studies.
Abstract: Time is the crucial element in restorative state control for electric power systems. One method for reenergizing large portions of a blacked out electric power system with a minimum of switching and thus time to restoration, is described. Results of a simulated system restart utilizing actual power system facilities are compared to power flow studies. The simulation tests were performed on the Los Angeles Department of Water and Power (LADWP) system in order to verify the concept of utilizing generation operating at extremely low voltage to energize as large a part as possible of the unloaded bulk power transmission system located within the service area.
42 citations
TL;DR: The optimal compensating strategy that suited the random fluctuated two-phase loads is analyzed and designed based on a real traction substation, for the purposes of satisfying the power quality standard, enhancing RPFC's control flexibility, and decreasing converter's capacity.
Abstract: Focusing on the freight-train dominant electrical railway power system (ERPS) mixed with ac–dc and ac–dc–ac locomotives (its power factore[0.70,0.84]), this paper proposes a power factor-oriented railway power flow controller (RPFC) for the power quality improvement of ERPS. The comprehensive relationship of the primary power factor, converter capacity, and the two-phase load currents is built in this paper. Besides, as the main contribution of this paper, the optimal compensating strategy that suited the random fluctuated two-phase loads is analyzed and designed based on a real traction substation, for the purposes of satisfying the power quality standard, enhancing RPFC's control flexibility, and decreasing converter's capacity. Finally, both the simulation and the experiment are used to validate the proposed conceive.
42 citations
TL;DR: In this article, a region where a set of initial values converges to a stable load flow solution under specified conditions, is investigated theoretically when the Newton-Raphson method is applied to a subset of nodal power equations expressed in either polar or rectangular coordinates.
Abstract: Because load flow problems are expressed as sets of nonlinear simultaneous equations, they have no unique solutions. In this paper a region where a set of initial values converges to a stable load flow solution under specified conditions, is investigated theoretically when the Newton-Raphson method is applied to a set of nodal power equations expressed in either polar or rectangular coordinates. The results are tested in load flow calculations on a 28-node power system and the convergence characteristics for the two types of coordinates are compared.
42 citations