Analysis of Stationary- and Synchronous-Reference Frames for Three-Phase Three-Wire Grid-Connected Converter AC Current Regulators

The current state of the art shows that unbalance and distortion on the voltage waveforms at the terminals of a grid-connected inverter disturb its output currents. This paper compares AC linear current regulators for three-phase three-wire voltage source converters with three different reference frames, namely: (1) natural (abc), (2) orthogonal stationary (αβ), and (3) orthogonal synchronous (dq). The quantitative comparison analysis is based on mathematical models of grid disturbances using the impedance-based analysis, the computational effort assessment, as well as the steady-state and transient performance evaluation based on experimental results. The control scheme devised in the dq-frame has the highest computational effort and inferior performance under negative-sequence voltage disturbances, whereas it shows superior performance under positive-sequence voltages among the reference frames evaluated. In contrast, the stationary natural frame abc has the lowest computational effort due to its straightforward implementation, with similar results in terms of steady-state and transient behavior. The αβ-frame is an intermediate solution in terms of computational cost.This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001.© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed

Axillobifemoral Bypass: A Brief Surgical and Historical Review

Peripheral artery disease (PAD) occurs when plaque accumulates in the arterial system and obstructs blood flow. Narrowing of the abdominal aorta and the common iliac arteries due to atherosclerotic plaques restricts blood supply to the lower limbs. Clinically, the lower limb symptoms of PAD are intermittent claudication, discoloration of the toes, and skin ulcers, all due to arterial insufficiency. Surgical revascularization is the primary mode of treatment for patients with severe limb ischemia. The objective of the surgical procedure is to bypass a blockage in an occluded major vessel by constructing an alternate route for blood flow using an artificial graft. This article presents information on aortoiliac reconstruction, with an emphasis on axillobifemoral bypass grafting.

Broadband terahertz pulse generation driven by an ultrafast thin-disk laser oscillator

We demonstrate broadband THz generation driven by an ultrafast thin-disk laser (TDL) oscillator. By optical rectification of 50-fs pulses at 61 MHz repetition rate in a collinear geometry in crystalline GaP, THz radiation with a central frequency at around 3.4 THz and a spectrum extending from below 1 THz to nearly 7 THz are generated. We realized a spectroscopic characterization of a GaP crystal and a benchmark measurement of the water-vapor absorption spectrum in the THz range. Sub-50-GHz resolution is achieved within a 5 THz bandwidth. Our experiments show the potential of ultrafast TDL oscillators for driving MHz-repetition-rate broadband THz systems

Transformerless parallel connection of voltage source converters - characteristics and control strategies.

Os elevados níveis de potência e desempenho solicitados pelas presentes e futuras aplicações de conversores estáticos de potência podem ser atingidos pela interconexão de unidades básicas menores (multiconversor). Com a utilização de uma estratégia de controle adequada consegue-se não apenas a potência total desejada e sua correta divisão entre as várias unidades básicas como também uma redução no conteúdo harmônico das correntes e tensões resultantes. Neste trabalho, algumas topologias de multiconversores monofásicos do tipo fonte de tensão são modeladas, analisadas e comparadas quanto às solicitações de corrente e tensão nos diversos componentes, e quanto ao espectro da corrente resultante. Desta discussão conclui-se que a \"Conexão em Paralelo de Conversores Sem Transformador\" (PCTL- parallel connection/transformerless) é viável, levando-se em conta as demais topologias e a tecnologia disponível em semicondutores de potência. A análise do modelo matemático e da matriz de controlabilidade do caso PCTL trifásico resulta em métodos de desacoplamento das entradas do multiconversor. Baseando-se nestes métodos, são propostas três estratégias de controle utilizando controladores de corrente monofásicos individuais. Dois deles utilizam PWM com portadora triangular, e o outro, um PWM por banda de tolerância. Para um dos casos, baseados em PWM a portadora triangular, propõe-se um processo de minimização de harmônicos de corrente, injetando-se à referência de cada modulador PWM um sinal de \"seqüência zero instantânea\", obtido a partir da solução de um problema de otimização. Para o caso baseado em banda de tolerância, conseguem-se satisfazer os critérios de desacoplamento pela sincronização e igual defasagem das funções de chaveamento dos diversos conversores via malhas PLL, e também pela injeção de uma corrente fictícia de \"seqüência zero instantânea\" às referências do controlador de corrente. Para os controladores propostos, discute-se a operação do PCTL durante a ocorrência de falhas ou manutenção. Apenas os conversores do tipo fonte de tensão são abordados neste trabalho.The high power and performance levels required for the present and future power electronics converters can be achieved by connecting a set of smaller power units (multiconverter). By using appropriate control, not only perfect sharing of the power among the converters, but also harmonics reduction is obtained. This thesis presents, analyses and compares some multiconverter topologies, based on the values of the voltages and currents in the main components and in the spectra of the resulting current. As a result, the transformerless parallel connection of converters PCTL is shown to be a feasible solution, taking into account the existing power devices technology. The analysis of the three phase PCTL model and its controllability matrix suggests methods for decoupling the PCTL inputs. This results in two methods using carrier based current controller and one method using a \"tolerance band (TB)\" based controller. For the carrier based one, the injection of an optimized zero sequence reference voltage produces a reduction in the ripple of the individual currents. For the tolerance based one, the inputs coupling is reduced by the use of PLL synchronized PWM and by the injection of a \"fictitious zero sequence current in the TB controller. The operation of the PCTL under faults and maintenance condition is discussed. Only the voltage source converter is studied here

Improved rectifiers.

Os populares retificadores monofásicos com filtro capacitivo apresentam baixo fator de potência além de causarem perturbações na rede e equipamentos a ela associados. São apresentados alguns circuitos, tanto passivos como ativos, que minimizam os problemas acima citados. Um deles, a fonte com indutor e capacitor na entrada, é analisado com detalhes. Através de dados obtidos em simulações digitais foram elaborados gráficos, a serem utilizados para o dimensionamento da fonte. É feita também a verificação experimental para validação destes gráficos.The well known single-phase capacitor filter rectifier offers low power-factor and disturbances in the mains and its associated equipments. Passive and active circuits are described that minimize the above mentioned problems. A detailed analysis is presented for one of them, the inductor-capacitor input supply. Data obtained from computer simulations are presented in a set of graphics, so as to make possible its use for design. Experimental verification of them is also presented

Transformerless parallel connection of voltage source converters - characteristics and control strategies.

Os elevados níveis de potência e desempenho solicitados pelas presentes e futuras aplicações de conversores estáticos de potência podem ser atingidos pela interconexão de unidades básicas menores (multiconversor). Com a utilização de uma estratégia de controle adequada consegue-se não apenas a potência total desejada e sua correta divisão entre as várias unidades básicas como também uma redução no conteúdo harmônico das correntes e tensões resultantes. Neste trabalho, algumas topologias de multiconversores monofásicos do tipo fonte de tensão são modeladas, analisadas e comparadas quanto às solicitações de corrente e tensão nos diversos componentes, e quanto ao espectro da corrente resultante. Desta discussão conclui-se que a \"Conexão em Paralelo de Conversores Sem Transformador\" (PCTL- parallel connection/transformerless) é viável, levando-se em conta as demais topologias e a tecnologia disponível em semicondutores de potência. A análise do modelo matemático e da matriz de controlabilidade do caso PCTL trifásico resulta em métodos de desacoplamento das entradas do multiconversor. Baseando-se nestes métodos, são propostas três estratégias de controle utilizando controladores de corrente monofásicos individuais. Dois deles utilizam PWM com portadora triangular, e o outro, um PWM por banda de tolerância. Para um dos casos, baseados em PWM a portadora triangular, propõe-se um processo de minimização de harmônicos de corrente, injetando-se à referência de cada modulador PWM um sinal de \"seqüência zero instantânea\", obtido a partir da solução de um problema de otimização. Para o caso baseado em banda de tolerância, conseguem-se satisfazer os critérios de desacoplamento pela sincronização e igual defasagem das funções de chaveamento dos diversos conversores via malhas PLL, e também pela injeção de uma corrente fictícia de \"seqüência zero instantânea\" às referências do controlador de corrente. Para os controladores propostos, discute-se a operação do PCTL durante a ocorrência de falhas ou manutenção. Apenas os conversores do tipo fonte de tensão são abordados neste trabalho.The high power and performance levels required for the present and future power electronics converters can be achieved by connecting a set of smaller power units (multiconverter). By using appropriate control, not only perfect sharing of the power among the converters, but also harmonics reduction is obtained. This thesis presents, analyses and compares some multiconverter topologies, based on the values of the voltages and currents in the main components and in the spectra of the resulting current. As a result, the transformerless parallel connection of converters PCTL is shown to be a feasible solution, taking into account the existing power devices technology. The analysis of the three phase PCTL model and its controllability matrix suggests methods for decoupling the PCTL inputs. This results in two methods using carrier based current controller and one method using a \"tolerance band (TB)\" based controller. For the carrier based one, the injection of an optimized zero sequence reference voltage produces a reduction in the ripple of the individual currents. For the tolerance based one, the inputs coupling is reduced by the use of PLL synchronized PWM and by the injection of a \"fictitious zero sequence current in the TB controller. The operation of the PCTL under faults and maintenance condition is discussed. Only the voltage source converter is studied here

Contemporary trends of social policy in Ukraine

The aim of the article is to analyze and to present contemporary trends and problems of various social policy areas in Ukraine. This country partly declares pro-occidental development course and its efforts to reform the social policy and to improve the administration of social services institutions are observable. Social policy of Ukraine is analyzed in a broad sense including such fields (social policy subsystems): Ukrainian social and economical development and its evaluation, social care problems, the youth policy sphere, the training system of social workers, a situation of human trafficking, the pre-vention of socially dangerous illnesses, the Ukrainian education policy tendencies, the pension system. A conclusion is drawn, that Ukrainian Social Policy Model must represent social, economic and cultural traditions; furthermore, the present internal facts of public life. Nowadays, there is an oligarchic market economy in Ukraine, and for this reason the country needs a motivation - a corporate social policy model. The government should stimulate (motivate) oligarchs (for example, by reducing taxes) to invest in social purpose objects and in this way to conduce towards the preservation of social peace in Ukrainian society.Straipsnyje analizuojamos šiuolaikinės Ukrainos socialinės politikos įgyvendinimo problemos. Aptarta Ukrainos pasirinkta socialinio - ekonominio regionų vertinimo sistema. Analizuojant jaunimo politikos Įgyvendinimą daroma išvada, kad Ukrainos valstybės tarnautojams, atsakingiems už jaunimo politikos Įgyvendinimą svarbu nustatyti kvalifikacijos standartus. Pastebima, kad Ukrainos švietimo politikos modernizavimas siejamas tiek su švietimo sistemos decentralizavimu, tiek su gebėjimų prioriteto užtikrinimu šios šalies lavinimo ir mokymo struktūrose. Aptariant prekybos žmonėmis problemą išryškinamos kovos su Šia blogybe priemonės. Vertinant sveikatos apsaugos reformą akcentuojama, kad Ukraina tęsia draudiminės medicinos reformą o pensijų reformų srityje remiasi teigiama ir neigiama šių reformų pasekmių kitose Vidurio Europos šalyse patirtimi. Apibendrinant teigiama, kad, atsižvelgiant Į susiklosčiusią oligarchinę šalies rinkos ekonomiką Ukrainos socialinė politika orientuojama Į motyvacinę korporacinę „ gerovės valstybės " kryptį

Alcoholism as Career

Situation in life, use of alcohol and alcohol career of alcoholics. Topics: 1. illness case history by doctor in attendance. 2. theme conversation: reference person and judgement on relationship with this person; contact intensity; judgement on common leisure behavior with reference person; perceived changes in the relation; frequency and type of conflicts; problem solution resulting from conflicts; sexual practices sober and drunk; responsibility for raising children and care of children; judgement on contact with one´s own parents; significance of family and occupation; satisfaction with housework (only for housewives); reasons for non-marriage (only for singles); detailed information on professional career; frequency of changes of company and reasons for these; work orientation; anomy; detailed information on general ability to establish contacts and alcohol-specific changes of this ability to establish contacts; memberships; hobby; leisure activities; watching television; feeling of boredom; detailed information on personal alcohol career; place and effects of the use of alcohol; difficulties experienced from the use of alcohol and resulting sanctions; measures and treatments against the use of alcohol; assumed heterostereotype of the alcoholic or a former alcoholic; assumed reasons for alcoholism; number of alcohol-specific treatments before the current treatment; time of first or last treatment; type of treatment; treatment length; type of resulting therapies and result evaluation; initiators of earlier treatments and manner of admission; resulting stigmatization after earlier treatments; relapses and relapse situation; personal readiness for and attitude of social surroundings to stationary treatment; delinquency; current legal status (legally incapacitated); current manner of admission; participation of others in the compulsory hospitalization; cause for admission; changes in relations through readiness for treatment; personal expectations of the clinic stay; cooperative conduct in personal therapy; concept of a clinic and therapy; length of stay sought; attitude to treatment of alcoholics in the psychiatric ward; attitude to secrecy of the clinic stay; expected difficulties in the future; assessment of the future situation with occupation and family; follow-up treatments; ideas about further aid measures; personal infidelity or infidelity of partner; length of infidelity; condition of health of partner. Also encoded was the consistency of patient statements and file records; suicide attempts; suicide as threat or attempt to kill oneself. Demography: sex; age; marital status; religious denomination; place of residence and size of place of residence; size of place of birth; geographic mobility in the first years of life; child-raising persons; changes of family situation in childhood; number of siblings; position in sibling sequence; occupation of father or mother; occupational position of father or mother; judgement on economic conditions in one´s family during one´s childhood; age of spouse and age difference between partners; number of children; personal school education and that of partner; vocational training; personal employment and that of partner; personal occupation last learned or practiced and that of partner; income of head of household; type of right of disposal over income; respondent is head of household; characteristics of head of household; residential status. 3. catamnese after about one year: amount of time passed since discharge; place and type of interview; participants in the interview; survey atmosphere; survey behavior; atmosphere between the patient and his partner; information on proportion of conversation between patient and partner; residential status; perceived changes regarding the time of case history; size of residence; condition of residence; changes in marital status; changes in living together during the clinic time or in the time after the clinic stay; reference person and judgement on relations; right of disposal over income; contact intensity; reasons for conflict; problem solutions through conflicts; changes in family life and sexuality; changes in social contacts; leisure activities; watching television and feeling of boredom; occupational changes; vertical mobility; unemployment; reasons for lay-off; side jobs; employment of partner; primary bread-winner; problems in the search for work; influence of unemployment on personal self-esteem; detailed information on treatment career and ambulatory contacts; information on development of use of alcohol after clinic stay; resulting relapse; concealment of clinic stay or alcoholism; reactions to clinic stay; participation in social life; stigmatization of partner; alcohol or pill use of partner; support recived; change of company after clinic stay; current source of income; number of clinic stays; marriage length; dissatisfaction with ward life; anomy; delinquency; number of suicide attempts; manner of admission; length of stays on psychiatric ward and in prison.Lebenssituation, Alkoholkonsum und Alkoholkarriere von Alkoholikern. Themen: 1.)Krankheitsanamnese durch den behandelnden Arzt. 2.)Leitfadengespräch:Bezugsperson und Beurteilung des Verhältnisses zu dieser Person; Kontaktintensität; Beurteilung des gemeinsamen Freizeitverhaltens mit der Bezugsperson; wahrgenommene Veränderungen in der Beziehung; Häufigkeit und Art von Konflikten; erfolgte Problemlösung durch Konflikte; Sexualverhalten im nüchternen und betrunkenen Zustand; Verantwortung für die Kindererziehung und die Betreuung der Kinder; Beurteilung des Kontaktes zu den eigenen Eltern; Bedeutung von Familie und Beruf; Zufriedenheit mit der Hausarbeit (nur bei Hausfrauen); Gründe für Nichtheirat (nur bei Ledigen); detaillierte Angaben zur beruflichen Karriere; Häufigkeit von Betriebswechseln und Gründe für diese; Arbeitsorientierung; Anomie; detaillierte Angaben zur allgemeinen Kontaktfähigkeit und zu alkoholspezifischen Veränderungen dieser Kontaktfähigkeit; Mitgliedschaften; Hobbys; Freizeitaktivitäten; Fernsehkonsum; Gefühl der Langeweile; detaillierte Angaben zur eigenen Alkohol-Karriere; Ort und Wirkungen des Alkoholkonsums; aufgetretene Schwierigkeiten durch den Alkoholkonsum und erfolgte Sanktionen; Maßnahmen und Behandlungen gegen den Alkoholkonsum; vermutetes Heterostereotyp des Alkoholikers bzw. eines ehemaligen Alkoholikers; vermutete Ursachen des Alkoholismus; Anzahl der alkoholspezifischen Behandlungen vor der jetzigen Behandlung; Zeitpunkt der ersten bzw. letzten Behandlung; Behandlungsart; Behandlungsdauer; Art der erfolgten Therapien und Erfolgsbewertung; Initiatoren für frühere Behandlungen und Einweisungsmodi; erfolgte Stigmatisierungen nach früheren Behandlungen; Rückfälle und Rückfallsituation; eigene Bereitschaft und Einstellung der sozialen Umgebung zu einer stationären Behandlung; Delinquenz; derzeitiger juristischer Status (entmündigt); gegenwärtiger Einweisungsmodus; Beteiligung anderer an der Zwangseinweisung; Einweisungsanlaß; Beziehungsveränderungen durch die Behandlungsbereitschaft; eigene Erwartungen an den Klinikaufenthalt; kooperatives Verhalten bei der eigenen Therapie; Vorstellung von einer Klinik und einer Therapie; angestrebte Dauer des Aufenthalts; Einstellung zur Behandlung von Alkoholikern in der Psychiatrie; Einstellung zur Geheimhaltung des Klinikaufenthaltes; erwartete Schwierigkeiten für die Zukunft; Einschätzung der zukünftigen Situation in Beruf und Familie; Nachbehandlungen; Vorstellungen über weitere Hilfsmaßnahmen; eigene Untreue bzw. Untreue des Partners; Dauer der Untreue; Gesundheitszustand des Partners. Zusätzlich verkodet wurde die Konsistenz von Patientenangaben und Aktenunterlagen; Suizidversuche; Suizid als Drohung oder versuchte Selbsttötung. Demographie: Geschlecht; Alter; Familienstand; Konfession; Wohnort und Wohnortgröße; Größe des Geburtsortes; geographische Mobilität in den ersten Lebensjahren; Erziehungspersonen; Veränderungen der Familiensituation in der Kindheit; Geschwisterzahl; Stellung in der Geschwisterfolge; Beruf des Vaters bzw. der Mutter; berufliche Position des Vaters bzw. der Mutter; Beurteilung der wirtschaftlichen Verhältnisse in der Familie während der eigenen Kindheit; Alter des Ehepartners und Altersdifferenz zwischen den Partnern; Kinderzahl; eigene Schulbildung und die des Partners; Berufsausbildung; eigene Berufstätigkeit und die des Partners; letzter erlernter bzw. ausgeübter eigener Beruf und der des Partners; Einkommen des Haushaltvorstandes; Art der Verfügungsgewalt über das Einkommen; Befragter ist Haushaltsvorstand; Charakteristika des Haushaltvorstandes; Wohnstatus. 3.)Katamnese nach etwa einem Jahr: Vergangener Zeitraum seit der Entlassung; Ort und Art des Interviews; Teilnehmer des Interviews; Befragungsatmosphäre; Befragungsverhalten; Atmosphäre zwischen dem Patienten und seinem Partner; Angaben zum Gesprächsanteil zwischen Patient und Partner; Wohnstatus; wahrgenommene Veränderungen gegenüber dem Zeitpunkt der Anamnese; Wohnungsgröße; Zustand der Wohnung; Veränderungen im Familienstand; Veränderungen im Zusammenleben während der Klinikzeit bzw. in der Zeit nach dem Klinikaufenthalt; Bezugsperson und Beurteilung der Beziehungen; Verfügungsgewalt über das Einkommen; Kontaktintensität; Konfliktgründe; Problemlösungen durch Konflikte; Veränderungen im Familienleben und in der Sexualität; Veränderungen bei den Sozialkontakten; Freizeitbeschäftigungen; Fernsehkonsum und Gefühl der Langeweile; berufliche Veränderungen; vertikale Mobilität; Arbeitslosigkeit; Entlassungsgründe; Nebenbeschäftigungen; Berufstätigkeit des Partners; Haupternährer; Probleme bei der Arbeitssuche; Einfluß der Arbeitslosigkeit auf das eigene Selbstwertgefühl; detaillierte Angaben zur Behandlungskarriere und ambulanten Kontakten; Angaben zur Entwicklung des Alkoholkonsums nach dem Klinikaufenthalt; erfolgter Rückfall; Verheimlichung des Klinikaufenthaltes bzw. des Alkoholismus; Reaktionen auf den Klinikaufenthalt; Teilnahme am sozialen Leben; Stigmatisierungen des Partners; Alkohol- oder Tablettenkonsum des Partners; erhaltene Hilfestellungen; Firmenwechsel nach dem Klinikaufenthalt; derzeitige Einkommensquelle; Anzahl der Klinikaufenthalte; Ehedauer; Unzufriedenheit mit dem Stationsleben; Anomie; Delinquenz; Anzahl der Suizidversuche; Einweisungsmodus; Dauer von Psychiatrie- und Gefängnisaufenthalten