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.

Power system stability improvement by energy storage type STATCOM

Abstract: This paper describes an approach to design a damping controller of an energy storage type STATCOM. The energy storage type STATCOM (ESTATCOM) is an advanced flexible AC transmission system (FACTS) device, which controls both reactive and active power injection/absorption to the power system. It also provides a better power swing damping. Using a linearized block diagram proposed by the authors, the present study examines the design of the ESTATCOM damping controller. Several case studies have been performed to evaluate the power swing damping effect of the ESTATCOM on one-machine infinite bus system. The results of the study show that an ESTATCOM, which controls both reactive and active power injection/absorption to power system, has a more significant effect on power swing damping than that controlling the reactive power alone.

Analysis of Main Topologies of Shunt Active Power Filters Applied to Four-Wire Systems

Abstract: This paper presents a complete comparative study about the five most common configurations of shunt active power filter applied to four-wire distribution systems. In order to evaluate the applicability of the studied topologies, two scenarios of four-wire loads are investigated differing by level of zero-sequence harmonic contents. The analysis of simulation steady-state results comprise dc-link capacitor voltage and current stresses, harmonic distortion in grid currents, and semiconductor losses. The results show that structures with fourth inductor generate higher number of levels at output converter voltage. However, when they operate by compensating high levels of zero-sequence harmonics, they can present higher dc-link voltage and lower efficiency. Furthermore, system models, control strategy, and experimental results are presented as well.

Towards interval analysis of the load uncertainty in power electric systems

Abstract: The aim of this paper is to present a methodology based on interval mathematics to deal with load uncertainty in power electric systems. The approach is suitable to model two types of uncertainty in power flow analysis, namely: (i) the influence of the load measurement errors at all system buses on the voltage profile; (ii) the voltage profile behavior under a load variation during a specific period of time. This methodology entails an interval power flow model and the resulting interval nonlinear system is solved using Krawczyk's method. We implemented the algorithm in the Matlab environment using the IntLab toolbox. Results for IEEE test-systems and a comparison with related work are presented.

New VF-power system architecture and evaluation for future aircraft

Abstract: Conventional aircraft power system is a constant-frequency (CF) supply based on mechanical-regulated constant-speed mechanism that has relatively low efficiency. Replacing the CF system with variable-frequency (VF) power improves overall efficiency, and reduce the system's weight and volume. However, this creates a new tier of requirements and design challenges. Novel VF-power architecture is developed with minimization of the power losses throughout the stages of power conversions. Optimal partitioning and grouping of onboard AC loads has been discussed with specific system data. New VF-input multi-functional power converters are also briefly discussed.

A General Unified AC/DC Power Flow Algorithm With MTDC

Abstract: The aim of this paper is to derive a general AC/DC power flow model with Voltage Source Converter Multi-Terminal High-Voltage Direct Current Systems (VSC MTDCs). The equations of AC, DC grids, and VSCs are formulated in augmented rectangular coordinates. The proposed model is composed of two nodal equations and two power constraints for each AC bus, as well as one nodal equation and one power constraint for each DC bus. In this model, the VSC equations are included in the AC and DC grid model—its power balance equation and one of the control equations are regarded as the power constraints of the AC bus connected to it, whereas the other control equation is regarded as the power constraint of the DC bus connected to it. Therefore, the number of equations of the proposed model is determined only by that of AC and DC buses, and the model is systematically well organized; the variety of VSC control strategies and AC/DC linking configurations does not influence the overall structure. The proposed approach enables to solve the load flow of the most general AC/MTDC, consisting of multiple AC and DC grids connected by VSCs, and is suitable for control strategies including the droop control and any new ones in the future. The model also leads to higher computational efficiency. By demonstrations on AC/DC power systems with several VSCs, this method is proved to be effective, flexible, and efficient.