Development of Dynamic Equivalent Models for Large Scale Wind Power Plants

Thesis (Ph.D.)--University of Washington, 2014An individual wind turbine has trivial influence on existing power systems owing to its very small percentage of the total generation. In contrast, wind power plants (WPPs) that have large numbers of wind turbines in relatively small areas have significant impacts on the power systems, and thus their influence must be considered in the studies. This dissertation is of developing suitable dynamic models of WPPs for power system dynamics study. In this dissertation, dynamic equivalent models (DEMs) for large scale WPPs are proposed for the dynamics study. As the dynamics of a WPP are the resultant dynamics of interconnected multiple wind turbines, its DEM is developed based on the knowledge of individual wind turbines and their interactions. In addition, as the dynamics of individual wind turbines are related to their control scheme, this study explains how to achieve an optimized control scheme for them with the use of the DEM. For a certain purpose in which a WPP is considered as an external system for dynamics study of a power system, its DEM can be developed based on measurements at point of interconnection without any pre-knowledge of the WPP. For the case, this dissertation also proposes a DEM developed using an adaptive system identification method. In addition, this study explains how to model an adequate power system for simulation tests. The validities of the proposed DEMs developed in this dissertation are verified by the simulation results with the power system model

Two layer heat transfer model for supercritical fluid flow in a vertical tube

Experimental heat transfer data in a supercritical vertical upward CO(2) flow were analyzed, based on the relationship between the wall heat flux and mass flux, buoyancy and flow acceleration effects, and specific heat variation across the turbulent boundary layer. These analyses indicated that the flow acceleration and significant specific heat variation in the boundary layer greatly influenced the heat transfer phenomena under the tested experimental conditions. A two layer heat-transfer model that sufficiently reflects both the effects of flow acceleration and specific heat variation was proposed to quantify the heat-transfer characteristics of supercritical fluids. This model was based on the thermal resistance behavior in the viscous sub-layer and the buffer layer. In our assessment of this model, the Nusselt number calculated from various experiments agreed with our data within a margin of error of +/-30%. Also, the location of the peak inner wall temperature from experimental data almost coincided with the peak maximum thermal resistance in the viscous sub-layer, calculated using the proposed model. (C) 2011 Elsevier B.V. All rights reserved.X111211sciescopu

Scaling Analysis of Various Simulants for Sodium Thermal-hydraulic Experiment in a Reduced-height Scale Test Facility

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Numerical Investigation of Pressure Drop Characteristics in an Inclined Tube Bank of a Sodium-to-sodium Heat Exchanger

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Numerical Study on the Frictional Pressure Drop for the Shell-Side of Prototype Combined Heat Exchanger in a Sodium-cooled Fast Reactor

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evelopment of Thermal-hydraulic Scaled-down Model of the Combined Heat Exchanger for Water Mock-up Hydraulic Performance Test

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Preliminary Design Evaluation of IHTS-Combined Steam Generator Concepts for a Sodium-cooled Fast Reactor

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An Experimental Investigation on the Droplet Behavior Impacting a Hot Surface above the Leidenfrost Temperature

An appropriate model to predict the size of the droplets resulting from the break-up with the structures will help in a better understanding and modeling of the two-phase flow calculations in the simulation of a reactor core loss-of-coolant accident (LOCA). A droplet behavior impacting on a hot surface above the Leidenfrost temperature was investigated. Droplets of known size and velocity were impacted to an inclined plate of hot temperature, and the behavior of the droplets was observed by a high-speed camera. It was found that for droplets of Weber number higher than a certain value, the higher the Weber number of the droplet the smaller the secondary droplets. The COBRA-TF model over-predicted the measured secondary droplet sizes obtained by the present experiment. A simple model for the secondary droplet size was proposed using the mass conservation equation. The maximum spreading diameter of the droplets was also compared to previous correlations and a fairly good agreement was found. A better prediction of the heat transfer in the case of LOCA can be obtained with the presented model