Power sharing conditioning control in single-phase parallel distributed generations with simple improvement of droop control

Droop control is the critical solution for sharing the power demand between Distributed Generations (DGs) in islanding microgrid when there is no support from the electricity distribution grid. The droop control is applied as the local control scheme to achieve power sharing among parallel inverters with DG sources. As it has been well established, this control strategy is combined frequency and voltage droop method. In droop strategy, the voltage and frequency are drooped to a new rated value to ensure power load sharing. Therefore this project to have an improvement of the droop under self-frequency restoration method is adopted in order to obtain accurate power sharing and fast frequency tracking capability with better load sharing between parallel DGs are been conducted in this project. It is where the improved droop control is used to have faster restoration for the voltage and frequency to nominal values within a limited time and to ensure the proper power sharing between the DGs considering based on the rating of energy source. The performance of the proposed controller is implemented in MATLAB/Simulink software and compared by two simulation tests under two exigent load circumstances as well also as through the connection of DGs to the point of common coupling (PCC). It is to verify the proposed control model has capability to response accurately during the power transient and power sharing conditions at both DGs. In proportion, the implementation of frequency restoration loop to the improved droop control has create a condition where it knows as an autonomous smart grid system whereby the restoration of the frequency and voltage can be done automatically. As a result, the improved controller can achieve better steady-state performance and fast restoration tracking speed within 3.5ms with 2.8ms rise time as compared to 8.5ms rise time for the conventional droop control. It also reduces the overshoot during the load transient to 4% and increases the tracking efficiency by 90% as compared to the 40% overshoot and 85% efficiency for the conventional control. Hence, the autonomous smart microgrid system is successfully presented under this proposed controller along with accurate power sharing performance between DGs and fast frequency restoration

National and State Economic Impact of NETL

This report documents the development of state-level input-output models for Pennsylvania, West Virginia, and Oregon and the augmentation of the national input-output model that was developed previously for the project Valuing Domestically Produced Natural Gas and Oil . The state IO models were developed to assess the FY08 economic impacts of expenditures, employment, and research and development awards at the NETL sites located in Pittsburgh, PA; Morgantown, WV; and Albany, OR. The national IO model was developed to assess the FY08 economic impacts of NETL site expenditures, awards, and employment at the national level

Dielectric response of a polar fluid trapped in a spherical nanocavity

We present extensive Molecular Dynamics simulation results for the structure, static and dynamical response of a droplet of 1000 soft spheres carrying extended dipoles and confined to spherical cavities of radii $R=2.5$, 3, and 4 nm embedded in a dielectric continuum of permittivity $\epsilon' \geq 1$. The polarisation of the external medium by the charge distribution inside the cavity is accounted for by appropriate image charges. We focus on the influence of the external permittivity $\epsilon'$ on the static and dynamic properties of the confined fluid. The density profile and local orientational order parameter of the dipoles turn out to be remarkably insensitive to $\epsilon'$. Permittivity profiles $\epsilon(r)$ inside the spherical cavity are calculated from a generalised Kirkwood formula. These profiles oscillate in phase with the density profiles and go to a ``bulk'' value $\epsilon_b$ away from the confining surface; $\epsilon_b$ is only weakly dependent on $\epsilon'$, except for $\epsilon' = 1$ (vacuum), and is strongly reduced compared to the permittivity of a uniform (bulk) fluid under comparable thermodynamic conditions. The dynamic relaxation of the total dipole moment of the sample is found to be strongly dependent on $\epsilon'$, and to exhibit oscillatory behaviour when $\epsilon'=1$; the relaxation is an order of magnitude faster than in the bulk. The complex frequency-dependent permittivity $\epsilon(\omega)$ is sensitive to $\epsilon'$ at low frequencies, and the zero frequency limit $\epsilon(\omega=0)$ is systematically lower than the ``bulk'' value $\epsilon_b$ of the static primitivity.Comment: 12 pages including 17 figure

Who Are the Homeless? Numbers, Trends and Characteristics of Those Without Homes in Calgary

In 2008, Calgary was the first city in Canada to institute a 10-year plan to end homelessness. The plan was introduced in part due to the steady and rapid growth in homelessness in the city since 1992. Since 2008 growth in the number of homeless people has stopped despite a rapidly growing city. The number of people enumerated as homeless by point-in-time counts has fallen from 304 persons per 100,000 population to 256 persons per 100,000 population in 2014, a drop of more than 15 per cent. Looking beyond simple counts of the number of homeless people, we examine how people who are homeless use emergency shelters. Tracking shelter use over a five year period by nearly 33,000 individuals, we find that, contrary to what might be thought to be true, the great majority (86%) of people who use emergency shelters in Calgary do so very infrequently and for only short periods of time. Visiting shelters less than twice (on average), these “transitional” users stayed in shelters for an average of only 15 days spread during the five years of our study. Another 12% of people used emergency shelters more frequently; an average of 8 times spread over five years. These “episodic” users stayed for a total of 113 days on average. Only a tiny minority, just 1.6% of all shelter users, stayed in shelters for very long periods. These “chronic” users visited shelters an average of three and a half times and stayed a total of 928 days over the five years of our study. Because they stay in shelters for long periods, chronic shelter users occupy one-third of shelter beds. The implication of this is that finding stable, supportive housing for just 1.6% of those experiencing homeless – a total of about 900 individuals in Calgary -- would free-up one-third of beds in emergency shelters. Providing supportive housing for episodic users as well would free-up another one-third of beds and so enable shelter providers to focus on their main function as providers of emergency housing. Moving people from emergency shelters into supportive housing delivers savings in the form of reduced interactions for these people with the criminal justice and healthcare systems; savings that have been shown in other studies to significantly off-set the cost of supportive housing. Planning to end homelessness has always been an ambitious goal. While the homeless serving community has made significant gains in understanding how best to solve the problem, greater effort may be required of local, provincial and federal policy makers to find ways of resolving the issue that is at the heart of Calgary’s homelessness problem; namely, the lack of affordable rental accommodations

Social justice themed sermons from civic-minded clergy can push churchgoers towards greater activism to improve racial equality

Religion plays an important role in the lives of many Americans. But what role does religion and religious institutions play in motivating Americans to participate in politics? In their new book, R. Khari Brown, Ronald E. Brown, and James S. Jackson look at the role the spiritual and political efforts made by churches to improve human rights. They find that Black Americans are more likely than White and Hispanic Americans to believe that religious institutions have a moral obligation towards human rights activism, but that all groups are more likely to engage in acts like protests if they attend worship settings where they hear sermons about social justice issues and the importance of political activism

A theoretical and experimental investigation of the thermal buckling of flat rectangular plates

The thesis presents a theoretical and experimental investigation of the buckling of flat rectangular plates when subjected to symmetrical and asymmetrical temperature distributions over their lateral surfaces. These temperature distributions induce thermal stresses. Under certain conditions the compressive component of the induced thermal stresses causes the plate to buckle out of its own plane. The evaluation of the critical temperature, which initiates buckling, is carried out in two successive steps. 1. A solution of the biharmonic equation that governs the distribution of thermal stresses under stable conditions is obtained. 2. This stable state distribution of thermal stresses is utilised to obtain an approximate solution of the equation governing the stability of flat plates with internal varying stresses. This gives the value of the critical temperature at the onset of buckling. The subject matter of the thesis is divided into four parts PART I is a review of the published literature covering rigorous and approximate methods which have been used to determine the stable state distribution of thermal stresses and the evaluation of the critical buckling temperature. It also includes considerations of plate deflections in the post-buckling range with particular reference to the growth of the plate centre deflection with increasing values of plate temperature differential. PART II deals exclusively with the theoretical analysis and evaluation of the critical buckling temperature. It includes, as its first consideration, the determination of the steady state distribution of thermal stresses in the plate. An approximate solution of the biharmonic equation, governing the distribution of stresses is presented using the Kantorovitch. Method. This is followed by an original application of the Rayleigh-Ritz Method, to obtain an approximate solution of the biharmonic equation giving the thermal stresses in a polynomial form. This is followed by an investigation of the effects of plate aspect ratio and the degree of asymmetry of the temperature distributions on the value of critical temperature. The cases considered have, to the author's knowledge, not been investigated hitherto. The numerical work associated with the theoretical analysis was carried out on a 'Deuce' Computer using Alpha Code and General Interpretive Programmes. PART III presents the experimental work carried out in substantiation of the theoretical methods used in Part II. This covers the determination of the critical buckling temperatures and deformations of aluminium alloy plates, of aspect ratios ranging from one to three, subjected to symmetrical and asymmetrical temperature distributions. PART IV discusses, critically examines and summarises the comparison and correspondence obtained between the theoretically predicted and experimentally determined values of critical temperatures and deformations. It is shown that good agreement exists. The thesis concludes with six appendices which present detailed analyses and calculations followed by a bibliography

Racial Disparities between the Sex Steroid Milieu and the Metabolic Risk Profile

Aims and Method. The present study examined the relationship between the metabolic risk profile (MRP) and total testosterone (TT) and free testosterone using the free androgen index (FAI) and sex hormone binding globulin (SHBG) in 36 Caucasian American (CA) and 30 African-American (AA) women volunteering for a weight loss study. Results. After controlling for age, significant relationships were found between TT and diastolic blood pressure (P = .004 and P = .015 in CA and AA women, resp.). Additionally, total cholesterol (P = .003), low density lipoprotein cholesterol (P = .004), apolipoprotein B (P = .006), and the total cholesterol/high density lipoprotein cholesterol (P = .027) were significantly related to TT in AA women only. In CA women, similar measures of glucose/insulin status related to FAI, were also related to SHBG. In both CA and AA women, SHBG was related to waist (P = .031 and P = .022 resp.). Conclusion. Our findings showed racial disparities in the relationship between the sex steroid milieu and the MRP in overweight/obese CA and AA women