Novi pristup za poboljšanje karakteristika UPQC-a tijekom nesimetričnih i distorzijskih uvjeta tereta temeljen na teoriji trenutne snage

In order to deal with power quality problems under distortional and unbalanced load conditions, this paper presents a new control method for a four-wire three-phase unified power quality conditioner (UPQC) which is based on instantaneous power p-q theory. The proposed control approach is based on instantaneous power and is optimized by using a self-tuning filter (STF), without using any low-pass filters (LPFs) or phase locked loop (PLL), and without measuring load or filter currents. In this approach, the load and source voltages are used to generate the reference voltages of a series active power filter (APF) and source currents are used to generate the reference currents of a shunt APF. Therefore, the number of times that current is measured is reduced and system performance is improved. The performance of the proposed control approach is evaluated in terms of power factor correction, source neutral current mitigation, load balancing and mitigation of the current and voltage harmonics of distortional and unbalanced loads in a three-phase four-wire system. The results obtained by MATLAB/SIMULINK software show the effectiveness of the proposed control technique in comparison to the conventional p-q method.U ovom radu prikazana je nova metoda upravljanja za trofazni četverožični UPQC (engl. unified power quality conditioner) temeljena na teoriji trenutne vrijednosti snage koja je prikladna za upravljanje tijekom distorzijskih i nesimetričnih uvjeta na teretu. Predloženo upravljanje temelji se na teoriji o trenutnoj radnoj i jalovoj snazi i optimirano je korištenjem samopodešavajućeg fitera, bez korištenja niskopropusnih filtera ili PLL-a i bez mjerenja struje tereta i filtra. Korišteni su naponi na teretu i napon izvora kako bi se generirala referentna vrijednost napona aktivnog filtra, a struje izvora koriste se za generiranje referentne vrijednosti struje aktivnog filtra. Na taj način smanjen je broj mjerenja struje i sustav ima bolje značajke. Uz predloženi sustav upravljanja testire su mogućnosti korekcije faktora snage, smanjenja neutralne struje izvora, balansiranja tereta, smanjenje harmonika u struji i naponu. Rezultati dobiveni pomoću MATLAB/SIMULINK-a pokazuju učinkovitost predloženog sustava upravljanja

Control of Inverter-Interfaced Distributed Generation Units for Voltage and Current Harmonics Compensation in Grid-Connected Microgrids

In this paper, a new approach is proposed for voltage and current harmonics compensation in grid-connected microgrids (MGs). If sensitive loads are connected to the point of common coupling (PCC), compensation is carried out in order to reduce PCC voltage harmonics. In absence of sensitive loads at PCC, current harmonics compensation scenario is selected in order to avoid excessive injection of harmonics by the main grid. In both scenarios, compensation is performed by the interface converters of distributed generation (DG) units. Also, to decrease the asymmetry among phase impedances of MG, a novel structure is proposed to generate virtual impedance. At fundamental frequency, the proposed structure for the virtual impedance improves the control of the fundamental component of power, and at harmonic frequencies, it acts to adaptively improve nonlinear load sharing among DG units. In the structures of the proposed harmonics compensator and the proposed virtual impedance, a self-tuning filter (STF) is used for separating the fundamental component from the harmonic components. This STF decreases the number of phase locked loops (PLLs). Simulation results in MATLAB/SIMULINK environment show the efficiency of the proposed approach in improving load sharing and decreasing voltage and current harmonics

Freedom, Self-Consciousness and Identity The Theory of Freedom and Identity in Kant's Moral Philosophy

A review of arguments about freedom and ethics from ancient times to contemporary era would reveal diverse conceptions of the concepts of freedom and ethics. However, Kant has forwarded his positive theory of freedom as the best possible way of modern man's being in his scientific philosophy. He has formulated the foundations of independent concept of freedom, putting forth some concepts in close connection with the concepts of self-consciousness, inner identity and integrity that make modern man a man in its real sense. Kant's concept of freedom is strongly under the influence of philosophy of Rousseau; freedom is the highest embodiment of man, which is the result of his specific activity aimed at his intellectual and spiritual development. Kant's basic concept of ethic is that of free will which is self-propelled. The action or behavior arises from one's duty which directs man to act or behave morally. The present article is an attempt to elaborate these concepts from the viewpoint of Kant and also to discuss his answer to the following question: How modern man is educated and raised? یک بازنگری به جستارهای آزادی و اخلاق از عصر باستان تا دوره معاصر، تصورهای متنوعی از مفاهیم آزادی و اخلاق را آشکار می‌کند؛ اما کانت نظریه ایجابی (تحصلی) آزادی خود را به عنوان برترین طریقه ممکن هستی انسان مدرن در فلسفه علمی خود طرح کرده است. او ضمن تدوین مبانی مفهوم مستقل آزادی، مفاهیم مرتبط با آن یعنی خودآگاهیِ اخلاقی، هویت درونی و یکپارچگی‌ را (که انسان مدرن را به مفهوم واقعی کلام «انسان» می‌کند) مطرح می‌کند. مفهوم آزادی کانت متأثر از فلسفه روسو است؛ آزادی، برترین تعیّن انسان است که نتیجه فعالیت خاص انسان برای توسعه استعداد فکری و روحی خود است. مفهوم اصلی اخلاق کانت، مفهوم اراده خود مختار است؛ رفتاری که از او نشئت می‌گیرد، تحت هدایت وظیفه‌ای است که دستور رفتار اخلاقی بر آن استوار است. این مقاله به تبیین زوایای مختلف این مفاهیم از دیدگاه کانت می‌پردازد و پاسخ او به این پرسش را که «چگونه انسان مدرن تربیت و پرورش می‌یابد؟» با خوانندگان در میان می‌نه