Upravljanje proizvodnom jedinicom spojenom na mrežu tijekom nesimetričnih napona na mreži temeljeno na kliznom režimu

The increasing presence of inverter-based distributed generation (DG) units in distribution networks (DNs) requires control methods that achieve high performance not only during normal operating conditions, but also under unbalanced conditions. With a high probability, a type of voltage unbalance in DNs is unequal three-phase voltage magnitudes at the fundamental system frequency. This can occur temporarily due to faults or permanently due to uneven distribution of unbalanced loads, on the three-phases of the DN. This paper proposes a sliding mode (SM) based controller for grid-connected DG units, under unbalanced grid voltage condition. The proposed control strategy employs a nonlinear control scheme to directly cancel out the negative-sequence (NS) components of DG output current under unbalanced voltage condition; and directly regulate the positive-sequence (PS) active and reactive power injected by DG units to main-grid. The control method proposed in this paper is shown to be robust and stable system parameter uncertainties. The validity and effectiveness of the proposed controller is verified by using time-domain simulation studies, under the MATLAB/Simulink software environment.Povećanje udjela distribuiranih proizvodnih jedinica povezanih na mrežu frekvencijskim pretvaračima zahtjeva metode upravljanja koje dobro djeluju tijekom normalnih uvjeta na mreži kao i u nesimetričnim uvjetima. Najčešći tip nesimetričnog napona na distribuiranoj jedinici je nesimetrična amplituda trofaznog napona na fundamentalnoj frekvenciji. To se događa privremeno zbog kvarova ili trajno zbog nejednake distribucije nesimetričnih tereta na tri faze distribuirane proizvodne jedinice. U ovom radu predlaže se regulator temeljen na kliznom režimu za upravljanje proizvodnom jedinicom spojenom na mrežu tijekom nesimetričnih napona na mreži. Predložena strategija upravljanja koristi nelinearnu shemu upravljanja kako bi se izravno poništile inverzne komponente izlazne struje tijekom nesimetričnih uvjeta; i izravno upravlja direktnom komponentom radne i jalove snage isporučene u mrežu. Metoda upravljanja predložena u ovom radu pokazala se kao robusna i stabilna uz nesigurne parametre sustava. Opravdanost i učinkovitost predloženog regulatora provjerena je korištenjem simulacija u MATLAB/Simulinku

Information Technology Proposal for the Town of Spencer

The Town of Spencer came to us looking for a plan to build and maintain their own personal fiber network for connection between departments and to improve data security for important information. After assessing the existing landscape and determining the various paths forward, we created network diagrams and plans for the movement forward of this project. After assessing a variety of plans, we found that a full single-mode fiber network would be the best system for the implementation in Spencer. While it was the highest cost, it also scored the highest in our assessment

Hyperinsulinemic Euglycemia Therapy for Acute Nitroglycerin Poisoning: Case Report

Nitroglycerin, a vasodilator, is commonly administered to treat ischemic heart disease. Adverse effects after toxicity are light-headedness, nausea, blurry vision, and syncope due to low systolic blood pressure as well as methemoglobinemia. A 19-year-old female was admitted to our toxicology department after suicidal ingestion of 320 mg extended-release nitroglycerin about 45 minutes before the admission. She was conscious, and her initial blood pressure was 98/65 mm Hg, which was decreased to 77 mmHg within 1.5 hours despite administration of 1 liter of normal saline. Due to severe hypotension, norepinephrine infusion was started for systolic blood pressure maintenance above 80mm Hg; however, she started complaining of palpitation and chest pain. So, the dose of norepinephrine was reduced, and glucose, insulin, and potassium protocol were started. After 3 hours of therapy, her hemodynamic condition stabilized with systolic blood pressure above 90mm Hg; hence norepinephrine was discontinued. She was discharged on the 3rd day after the psychiatric consultation, with regular clinical and paraclinical examinations

Islamic Principles and Culture Applied to Improve Life Quality in Islamic Cities

AbstractCities, towns, and residential area compounds constitute the most salient and tangible manifestations of human culture. The objectives of this study were in three folds. First to identify principles of modern urban planning and living. Secondly, to identify Islamic ideology basis to Quran and conduct of prophetic relative to urban planning and living and finally, to identify Islamic urban planning joined to present condition and knowledge. Strategy for the research design involved Post-Occupancy Study (POE) upon Islamic cities monuments within the metropolitan city of Esfahan, Iran. In this study, it was realized that the strategies proposed in this study is changeable with the geographic and cultural conditions

Cycle-life of Li-ion Capacitors: Factors Influencing Aging

A comprehensive study of the factors influencing the cycle life of Li-ion capacitors (LiCs) at different stages of aging is essential for a promising LiC energy management system. This digest explicitly studies the factors influencing the initial stage of aging of LiCs. The commercially available Musashi LiC cells are chosen to perform cyclic aging experiments under different test conditions, including temperature, C-rate, and cycle depth. The results demonstrate the impact of the test conditions on LiC aging. A notable observation is that depth-of-discharge also significantly affects the initial aging stage. Finally, the Arrhenius equation has been applied to the test results and qualitatively analyzed the cell degradation mechanism

Nanotechnology and supercritical fluids

Supercritical fluid (SCF) technology has become an important tool of materials processing in the last two decades. Supercritical CO2 and H2O are extensively being used in the preparation of a great variety of nanomaterials. The interest in the preparation and application of nanometer size materials is increasing since they can exhibit properties of great industrial interest. Several techniques have been proposed to produce nanomaterials using supercritical fluids. These processes, taking advantage of the specific properties of supercritical fluids, are generally flexible, more simplified and with a reduced enviromental impact. The result is that nanomaterials with potentially better performances have been obtained. We propose a critical review of the supercritical based techniques applied to the production of nanoparticles materials.Keywords: Supercritical fluids; Nanoparticles; SCF technology; RESS; SAS

Sensorless Control of a Single-Phase AC-DC Boost Converter without Measuring Input Voltage and Current

It is well-known that the accurate measurement of input voltage and current, as the feedforward and feedback terms, plays a crucial role in the nonlinear controller design for power factor compensation of an AC-DC boost converter. This paper addresses the problem of the simultaneous estimation of the input voltage and current from the output voltage in a full-bridge AC-DC boost converter. In the lossless model of the system, those variables are unobservable from the output voltage when the control input is zero. To overcome this, the system dynamics are immersed in a proper form by a new filtered transformation. The phase and amplitude of the input voltage, along with the input current, are globally estimated from the output voltage by a fifth-dimensional estimator. Unlike some existing results, the stability of the proposed estimator does not rely on a priori knowledge about the parasitic resistances and is guaranteed exponentially under the persistence of excitation conditions on the control signal. An application of the proposed estimator is presented in conjunction with a dynamic controller to form a sensorless control algorithm that does not require any sensor on the input side and controls the system only by the feedback from the output voltage. Processor-in-the-loop (PIL) studies conducted by OPAL-RT OP 5700 are used to assess the performances of the proposed estimator and controller