Social and Behavioral Sciences Commons^™

Impact Of Wind Generation Mix On Transient Stability For An Interconnected Power System, Lasantha Meegahapola, Damian Flynn, Jason Kennedy, Tim Littler

Dr Lasantha G Meegahapola

The rapid growth of wind generation in many European countries is pushing power systems into uncharted territory. As additional wind generators are installed, the changing generation mix may impact on power system stability. This paper adopts the New England 39 bus system as a test system for transient stability analysis. Thermal generator models are based on a likely future plant mix for existing systems, while varying capacities of fixed-speed induction generators (FSIG) and doubly-fed induction generators (DFIG) are considered. The main emphasis here has been placed on the impact of wind technology mix on inter-area oscillations following transient grid disturbances. …

Characterisation Of Flicker Emission And Propagation In Distribution Networks With Bi-Directional Power Flows, D Perera, L Meegahapola, S Perera, P Ciufo

Dr Lasantha G Meegahapola

With the increasing penetration levels of intermittent and fluctuating energy sources such as wind generating systems in the electricity grid, resulting voltage fluctuations and flicker can be expected to become an important power quality considerations. Due to significant bidirectional power flows resulting from large renewable power generation systems connected to downstream, voltage fluctuations may propagate from downstream to upstream. The work presented in this paper investigates and characterises flicker emission and propagation resulting from fluctuating generating sources connected to a distribution network. Mathematical models are developed for flicker emission under different generator control strategies and flicker propagation to upstream network. …

Comparative Analysis Of Dynamic Line Rating Models And Feasibility To Minimise Energy Losses In Wind Rich Power Networks, Mathew Simms, Lasantha Meegahapola

Dr Lasantha G Meegahapola

Wind power generation has indicated an exponential increase during last two decades and existing transmission network infrastructure is increasingly becoming inadequate to transmit remotely generated wind power to load centres in the network. The dynamic line rating (DLR) is one of the viable solutions to improve the transmission line ampacity during high wind penetration without investing on an additional transmission network. The main objective of this study is to identify the basic differences between two main line rating standards, since transmission network service providers (TNSPs) heavily depend on these two standards when developing their line rating models. Therefore, a parameter …

Optimal Power Flow With Variable Wind Conditions, S Durairaj, L Meegahapola, D Flynn, B Fox

Dr Lasantha G Meegahapola

This paper presents simulation studies of an electric arc furnace (EAF) model in the MATLAB/SIMULINK environment. EAF was modeled as a current source controlled by a non-linear resistance. Voltage flicker, a phenomenon of annoying light intensity fluctuation, caused by EAF, has been a major power quality concern for both power companies and customers. A model was developed for the electric arc furnace and it was applied in the simulation studies of distribution static synchronous compensator (DSTATCOM) for voltage flicker mitigation. The controller for DSTATCOM was designed based on DQ-model for the reactive power management which helps in the mitigation of …

Voltage And Power Quality Improvement Strategy For A Dfig Wind Farm During Variable Wind Conditions, L Meegahapola, T Littler, B Fox, J Kennedy, D Flynn

Dr Lasantha G Meegahapola

This paper presents a voltage and power quality enhancement scheme for a doubly-fed induction generator (DFIG) wind farm during variable wind conditions. The wind profiles were derived considering the measured data at a DFIG wind farm located in Northern Ireland (NI). The aggregated DFIG wind farm model was validated using measured data at a wind farm during variable generation. The voltage control strategy was developed considering the X/R ratio of the wind farm feeder which connects the wind farm and the grid. The performance of the proposed strategy was evaluated for different X/R ratios, and wind profiles with different characteristics. …

Impact On Transient And Frequency Stability For A Power System At Very High Wind Penetration, Lasantha Meegahapola, Damian Flynn

Dr Lasantha G Meegahapola

This paper analyzes the impact on transient and frequency stability for a power system at very high wind penetration (40% wind). Wind penetration is based on the doubly-fed induction generator (DFIG), and a systematic approach has been adopted for wind power integration. A sensitivity analysis has been carried out for each wind integration scenario and for different wind generator loading conditions. A range of fault locations has been selected for stability analysis based on the proximity to synchronous generation and wind farms. The analysis has shown that transient stability performance is subject to fault location in the network, especially when …

Optimal Allocation Of Reactive Power Resources To Minimise Losses And Maintain System Security, Eknath Vittal, Lasantha Meegahapola, Damian Flynn, Andrew Keane

Dr Lasantha G Meegahapola

Modern doubly-fed induction generator (DFIG) wind turbines have significant reactive power control capability, even during low wind speed conditions. This can improve system security by providing terminal voltage control at buses in the system. Generally, such control employs the full range of reactive power production from the turbine which can lead to increased system losses. By utilizing optimal power flow analysis, and limiting the range of reactive power production at certain wind farms, system losses can be minimized. If the reactive power of the wind farms are optimized to achieve the minimum system losses this may adversely affect the voltage …

Transient Stability Analysis Of A Power System With High Wind Penetration, Lasantha Meegahapola, Damian Flynn, Tim Littler

Dr Lasantha G Meegahapola

This paper presents transient stability analysis for a power system with high wind penetration. The transient stability has been evaluated based on two stability criteria: rotor angle stability and voltage stability. A modified IEEE-14 bus system has been used as the main study network and simulations have been conducted at several wind power penetration levels, defined as a fraction of total system generation. A wide range of scenarios have been presented based on the wind farm voltage at the point of connection, i.e. low voltage (LV) distribution level and high voltage (HV) transmission level, and the type of wind generator …

Multi-Objective Reactive Power Support From Wind Farms For Network Performance Enhancement, Lasantha Meegahapola, Brendan Fox, Tim Littler, Damian Flynn

Dr Lasantha G Meegahapola

This paper examines the ability of the doubly fed induction generator (DFIG) to deliver multiple reactive power objectives during variable wind conditions. The reactive power requirement is decomposed based on various control objectives (e.g. power factor control, voltage control, loss minimisation, and flicker mitigation) defined around different time frames (i.e. seconds, minutes, and hourly), and the control reference is generated by aggregating the individual reactive power requirement for each control strategy. A novel coordinated controller is implemented for the rotor-side converter and the grid-side converter considering their capability curves and illustrating that it can effectively utilise the aggregated DFIG reactive …

Voltage Security Constrained Reactive Power Optimization Incorporating Wind Generation, L G. Meegahapola, E Vittal, A Keane, D Flynn

Dr Lasantha G Meegahapola

This paper presents a comparative analysis between conventional optimal power flow (OPF) and voltage constrained OPF strategies with wind generation. The study has been performed using the New England 39 bus system with 12 doublyfed induction generator (DFIG) based wind farms installed across the network. A voltage security assessment is carried out to determine the critical wind farms for voltage stability enhancement. The power losses and individual wind farm reactive power generation have been compared with and without voltage stability constraints imposed on the OPF simulation. It is shown that voltage constrained OPF leads to much greater active power losses …

Capability Curve Based Enhanced Reactive Power Control Strategy For Stability Enhancement And Network Voltage Management, Lasantha Meegahapola, Tim Littler, Sarath Perera

Dr Lasantha G Meegahapola

Reactive power has become a vital resource in modern electricity networks due to increased penetration of distributed generation. This paper examines the extended reactive power capability of DFIGs to improve network stability and capability to manage network voltage profile during transient faults and dynamic operating conditions. A coordinated reactive power controller is designed by considering the reactive power capabilities of the rotor-side converter (RSC) and the grid-side converter (GSC) of the DFIG in order to maximise the reactive power support from DFIGs. The study has illustrated that, a significant reactive power contribution can be obtained from partially loaded DFIG wind …

Optimization Of Frt Active Power Performance Of A Dfig During Transient Grid Faults, L Meegahapola, Damian Flynn, Tim Littler

Dr Lasantha G Meegahapola

Optimal fault ride-through (FRT) conditions for a doubly-fed induction generator (DFIG) during a transient grid fault are analyzed with special emphasis on improving the active power generation profile. The transition states due to crowbar activation during transient faults are investigated to exploit the maximum power during the fault and post-fault period. It has been identified that operating slip, severity of fault and crowbar resistance have a direct impact on the power capability of a DFIG, and crowbar resistance can be chosen to optimize the power capability. It has been further shown that an extended crowbar period can deliver enhanced inertial …

The International Monetary Fund, Power Politics, And The Changing Political Economy Of The Twenty First Century, Eduardo Flores

UNLV Theses, Dissertations, Professional Papers, and Capstones

The governance of the global economy is in a constant state of change. Since the creation of the Bretton Woods system, the International Monetary Fund has had to pursue a series of reforms to meet the changing demands of the international monetary system. At times, the Fund's institutional design has been adjusted to reflect the rise and decline in economic fortunes of member states. Other times the Fund has been resistant to change. However, the original design has proved to be durable and has overcome a number of historical challenges. Currently, two realities are challenging the institutional design of the …

No Limits To Watching?, Katina Michael, M.G. Michael

M. G. Michael

Little by little, the introduction of new body-worn technologies is transforming the way people interact with their environment and one another, and perhaps even with themselves. Social and environmental psychology studies of human-technology interaction pose as many questions as answers. We are learning as we go: 'learning by doing' through interaction and 'learning by being'. Steve Mann calls this practice existential learning; wearers become photoborgs, a type of cyborg (cybernetic organism) whose primary intent is image capture from the domains of the natural and artificial. This approach elides the distinction between the technology and the human; they coalesce into one.

No Limits To Watching?, Katina Michael, M.G. Michael

Professor Katina Michael

Little by little, the introduction of new body-worn technologies is transforming the way people interact with their environment and one another, and perhaps even with themselves. Social and environmental psychology studies of human-technology interaction pose as many questions as answers. We are learning as we go: 'learning by doing' through interaction and 'learning by being'. Steve Mann calls this practice existential learning; wearers become photoborgs, a type of cyborg (cybernetic organism) whose primary intent is image capture from the domains of the natural and artificial. This approach elides the distinction between the technology and the human; they coalesce into one.

Power Motivates Interpersonal Connection Following Social Exclusion, Jayanth Narayanan, Kenneth Tai, Zoe Kinias

Research Collection Lee Kong Chian School Of Business

Research has systematically documented the negative effects of social exclusion, yet little is known about how these negative effects can be mitigated. Building on the approach-inhibition theory of power (Keltner, Gruenfeld, & Anderson, 2003), we examined the role of power in facilitating social connection following exclusion. Four experiments found that following exclusion, high power (relative to low power) individuals intend to socially connect more with others. Specifically, following exclusion, individuals primed with high power sought new social connections more than those primed with low power (Studies 1–4) or those receiving no power prime (Study 1). The intention to seek social …

Women And The Second Estate In 16th Century Zambezia: Gendered Powers, A 'Puppet' African Queen And Succession In Vakaranga Society, 1500–1700, George G. Levin

Master's Theses

Women in vaKaranga society of the 15th to 17th centuries have been portrayed as oppressed by an "extremely patriarchal" system, but the reality, while still fitting the simple classification of a 'patriarchal' monarchy, indicates quite a bit more negotiation of gendered powers than women, as a class, experienced in the Mediterranean or East Asia. The vaKaranga were the architects of Great Zimbabwe, the capital of a growing state, colonizing their cousins of the Zambezi river, which their Kusi-Mashariki Bantu forefathers had traversed southward a millennium before. Civil war had (apparently) split one nation into two states, Mutapa (Monomotapa) and Khami …

Agent-Based Demand Management In A Power Distribution Network By Considering Distributed Generations, Fenghui Ren, Minjie Zhang, Danny Soetanto

Dr Fenghui Ren

A distribution network carries electricity from transmission network to consumers through facilities such as substations, buses and feeders. Distributed generations emerge as the new alternative power resource to a distribution network at a smaller and distributed scale. On one hand, distributed generations can decrease substations' load and power price. On the other hand, they will bring difficulties to substations for demand management. This paper proposes a multiagent model to represent a radial distribution network. The model includes five types of agents, which are substation agents, bus agents, feeder agents, load agents and generation agents. Through communicating with neighbouring agents, each …

A Multiagent Approach For Decentralized Voltage Regulation In Power Distribution Networks Within Dgs, Fenghui Ren, Minjie Zhang, Danny Sutanto

Dr Fenghui Ren

Voltage regulation (VR) is a procedure to keep voltages in a distribution network (DN) within normal limits. Conven- tionally, a voltage regulator can read voltage levels from pre- dened measures, and regulate the voltages. However, due to lacking of a distributed generator's (DG) information, the unexpected electricity from a DG will mislead readings on voltages levels, so as to disturb the VR in a DN. Adjust- ing a DG's reactive power output is an alternative way for VR. However, because of limited penetration levels, DGs need to collaborate with other devices in order to provide an eective voltage regulation. Therefore, …

Women And Power In The United States: A Geographic Analysis Of Government, Work, And Economic Status, Kylie Stackis

Earth and Environmental Sciences Presentations

This geographic analysis investigates the different ways that women hold power across the United States, primarily through government, work, and economic status. Political power is in this case represented through government representation at the national and state level. Economic power considers employment, income, occupation (specifically traditionally male fields of business and science), hours worked, and Forbes lists of the richest 400 people in the United States as well as the 500 CEOs of influential companies. Education was a third variable in the analysis since it exemplifies the power of knowledge and lends itself to the potential for political and economic …

Course Syllabus (Fa13) Coli 211 Literature & Psychology: "Power, The Subject, And Technological Rationality", Christopher Southward

Comparative Literature Faculty Scholarship

Course Description and Objectives:

In this course, we will examine mechanisms of power and the processes by which these produce categories of subjectivity. Theoretically speaking, we will begin by considering these processes at the level of society and then dwell on their human experience at the level of the psyche. Here, we will aim to discover processes by which the subject reproduces conditions of domination by power at the level of psychic experience. Power-practices assume their condition of possibility by positing, on the one hand, that the category of the subject is a priori existent and, on the other, that …

How Do Mental Health Clincians Using Feedback Informed Treatment Methods Create A "Cultural Of Feedback" With Clients?, Alexander H. Tew

Theses, Dissertations, and Projects

This study was undertaken to explore how mental health clinicians using feedback informed treatment (FIT) interventions attempt to increase the likelihood of receiving genuine feedback from their clients. Furthermore, the study explores clinicians' perceptions about the ways in which interpersonal power dynamics, including race/ethnicity dynamics, influence the feedback process. An anonymous online survey was posted on two Internet forums for FIT practitioners. A final sample of thirty licensed mental health clinicians completed the mixed methods survey, answering five demographics questions (age, gender, race/ethnicity, years using FIT methods, and nationality) and three open-ended questions. The open-ended questions asked respondents to discuss …

Breathers, Releases, Outlets And Pauses: Employee Resistance In The Context Of Depersonalized Bullying, Premilla D'Cruz

The Qualitative Report

Drawing on a study rooted in van Manen’s hermeneutic phenomenology, conducted with agents working in international - facing call centers in Mumbai and Bangalore, India, this paper describes employee resistance to depersonalized bullying. Data were gathered through conversational interviews and subjected to selective and sententious thematic analyses. The theme of ‘breathers, releases, outlets and pauses’ captures both the various behaviours that participants engaged in to gain respite from and to acquire control over their oppressive work environment and the factors that determine their behaviours, namely, their professional identity and their job - related material gains. The findings not only further …

Transnational Capital And The Politics Of Global Supply Chains, Ronald W. Cox

Class, Race and Corporate Power

In the latest phase of globalization, transnational corporations based in the U.S. have worked closely with U.S. foreign policymakers to secure favorable foreign direct investment provisions within U.S. domestic legislation and within U.S. trade agreements. These interactions between transnational firms and the U.S. state have provided many of the preconditions for an expansion of foreign direct investment connected to capital liberalization and the growth of global supply chains from the 1980s to the present. This relationship is best conceptualized as representing a “transnational interest bloc,” whose policy objectives are incorporated within investment provisions in US-backed trade and investment agreements.

The Affective Power Of Sound: Oral History On Radio, Siobhan A. Mchugh

Siobhan McHugh

Using illustrative audio clips, this article offers insights into the historical symbiosis between oral history and radio and the relationship between orality, aurality, and affect that makes radio such a powerful medium for the spoken word. It does so through a discussion of the concept of affect as it applies to oral history on radio and through a description and analysis of crafting oral history for the radio documentary form. This article features audio excerpts from radio documentaries produced by the author. Listening to the audio portions of this article requires a means of accessing the audio excerpts through hyperlinks. …

Dynamics Of International Nonprofit Capacity Building Partnerships, Julia Sparkman

College of Communication Master of Arts Theses

This study worked to expand the discourse of international nonprofit capacity building research. In the field of Communication, research investigating international nonprofit partnerships is limited, and some international communities lack a voice within the scholarship. Through the lens of postcolonial reflexivity, the author traveled to Kenya to conduct participant observations and one-on-one interviews with a US Capacity Building Nonprofit (USCBN) and two local Kenyan nonprofit organizations (the KCN and the KSN). The findings revealed that the USCBN established previous organizational alliances with the KCN and the KSN. The previous alliances led to strong relationships. The relationships engendered collaboration within the …

A Pilot Test On The Role Of Power In Mate Choice, Addison Zhao

Honors Scholar Theses

To test two competing theories, social role and sexual strategies, a study was proposed to have participants evaluate dating profiles that varied in agency, communion, and status. Power was also manipulated to test for effects on likelihood to date an individual. To test methods used for the proposed study, a pilot study was conducted to evaluate the effectiveness of a power prime task, a manipulation check for the power prime task, the attractiveness of 24 pictures, and an analysis of 12 profiles. The study found that power priming with analogies did not significantly lead to participants feeling powerful. This finding …

Local Food And Power Dyanmics In Southeast Grand Rapids, Michigan, Christy Mello

Anthropology ETDs

Various types of food security' projects essentially deliver little in the way of real opportunities for local food security among Southeast residents in Grand Rapids, MI. Nonetheless, developers justifying their gentrifying efforts are increasingly funded through large grants and public dollars by actually purporting themselves to seek solutions to reducing food insecurity in these Southeast neighborhoods. 'Community,' 'local,' 'sustainability,' and 'social justice' are common terms marketed as values to promote urban redevelopment, food security initiatives, and to sell local food. Food growers and activists challenge how these terms are defined and used for profiteering. Thus, there are competing value systems …

"Democracy" In A Virtual World: Eve Online's Council Of Stellar Management And The Power Of Influence, Jessica Ireland

Theses and Dissertations

Interest in virtual worlds has grown within academia and popular culture. Virtual worlds are persistent, technologically-mediated, social spaces. Academic literature focuses on issues such as identity, sociality, economics, and governance. However studies of governance focus on internal or external modes of control; less attention has been paid to institutions of governance that operate within both the virtual and real worlds.

In EVE Online, the Council of Stellar Management (CSM) represents a joint venture between developers and users to shape the direction of EVE's virtual society. As a group of elected representatives, the CSM represents societal interests to the game's developer, …

Lm Tests Of Spatial Dependence Based On Bootstrap Critical Values, Zhenlin Yang

Research Collection School Of Economics

To test the existence of spatial dependence in an econometric model, a convenient test is the Lagrange Multiplier (LM) test. However, evidence shows that, in finite samples, the LM test referring to asymptotic critical values may suffer from the problems of size distortion and low power, which become worse with a denser spatial weight matrix. In this paper, residual-based bootstrap methods are introduced for asymptotically refined approximations to the finite sample critical values of the LM statistics. Conditions for their validity are clearly laid out and formal justifications are given in general, and in details under several popular spatial LM …