Ahmet Teke

A Novel Reference Signal Generation Method for Power-Quality Improvement of Unified Power-Quality Conditioner

This paper proposes a novel reference signal generation method for the unified power quality conditioner (UPQC) adopted to compensate current and voltage-quality problems of sensitive loads. The UPQC consists of a shunt and series converter having a common dc link. The shunt converter eliminates current harmonics originating from the nonlinear load side and the series converter mitigates voltage sag/swell originating from the supply side. The developed controllers for shunt and series converters are based on an enhanced phase-locked loop and nonlinear adaptive filter. The dc link control strategy is based on the fuzzy-logic controller. A fast sag/swell detection method is also presented. The efficacy of the proposed system is tested through simulation studies using the Power System Computer Aided Design/Electromagnetic Transients dc analysis program. The proposed UPQC achieves superior capability of mitigating the effects of voltage sag/swell and suppressing the load current harmonics under distorted supply conditions.

A robust control of dynamic voltage restorer using fuzzy logic

In this paper, a new control method for Dynamic Voltage Restorer (DVR) is described by combining fuzzy logic (FL) with a carrier modulated PWM inverter. The proposed control scheme is simple to design and has excellent voltage compensation capabilities. The proposed method for voltage sag/swell detection has the ability of detecting different kinds of power disturbances faster than conventional detection methods. Effectiveness of the proposed detection method is shown by the comparison with the conventional methods in the literature. Simulation results under unbalanced supply voltage are presented to evaluate the performance of the designed DVR.

Review of Multifunctional Inverter Topologies and Control Schemes Used in Distributed Generation Systems

Recent developments in power electronics technology have spurred interest in the use of renewable energy sources as distributed generation (DG) generators. The key component in DG generators is a grid-connected inverter that serves as an effective interface between the renewable energy source and the utility grid. The multifunctional inverter (MFI) is special type of grid-connected inverter that has elicited much attention in recent years. MFIs not only generate power for DGs but also provide increased functionality through improved power quality and voltage and reactive power support; thus, the capability of the auxiliary service for the utility grid is improved. This paper presents a comprehensive review of the various MFI system configurations for single-phase (two-wire) and three-phase (three- or four-wire) systems and control strategies for the compensation of different power quality problems. The advances in practical applications and recent research on MFIs are presented through a review of nearly 200 papers.

Dynamic control of unified power flow controller under unbalanced network conditions

Abstract The effective and reliable use of existing transmission lines are critically important because high-voltage transmission networks met enormous power demands are very expensive investments in terms of their costs. Flexible Alternating Current Transmission Systems (FACTS) are quite efficient to control the power flow of the transmission lines and increase the current capacity of system. Unified Power Flow Controller (UPFC) is the more efficient among FACTS equipments which have the potential to increase the power flow and stability of the transmission line. This paper develops new control approaches for both series and shunt inverters of UPFC. The proposed controller algorithms of shunt and series inverters are based on fuzzy logic controller and rotating orthogonal-coordinate method, respectively. Dynamic control of power flow using proposed UPFC is analyzed as mathematically. Power System Computer-Aided Design (PSCAD) is used to simulate the system and test UPFC in the simulation environment. The test results are presented to show the increased stability of the system and improved dynamic response of UPFC during faults occurred in the transmission line.

Implementation of a Non-Linear Adaptive Filter Based Sag Detection Method for Dynamic Voltage Restorers under Unbalanced Fault Conditions

The most common power quality problems in distribution systems are related to unbalanced voltage sags. Voltage sags must be detected quickly and corrected in a minimum amount of time. One of the most widely used methods for sag detection is based on the d-q transformation. This method has the disadvantage of missing the detection of unbalanced faults, because this method uses a voltage sag level signal obtained from the average of 3 phases for sag detection. In this paper, an adaptive filter sag detection method is proposed for Dynamic Voltage Restorers (DVR) under unbalanced fault conditions. The proposed DVR controller is able to detect balanced, unbalanced and single phase voltage sags. A novel reference voltage generation method is also presented. To validate the proposed control methods, a 3-phase DSP controlling a DVR prototype with a power rating of 1.5-kVA has been developed. Finally, experimental results are presented to verify the performance of the proposed control methods.

Implementation of Fuzzy Logic Controller Using FORTRAN Language in PSCAD/EMTDC

Fuzzy logic controllers have gained widespread use by engineers and practitioners due to their design simplicity, closeness to human reasoning and suitability for control applications. Fuzzy logic controlled studies are usually performed in MATLAB, or sometimes in PSCAD/EMTDC (Power Systems Computer Aided Design/Electromagnetic Transient including d.c.) with MATLAB interfacing. The PSCAD/EMTDC software does not include a component for a fuzzy logic controller. This paper is, to the best of our knowledge, the first work that designs and implements a fuzzy logic controller in PSCAD/EMTDC by using FORTRAN codes. In this way, several drawbacks which arise from the interfacing between MATLAB and PSCAD/EMTDC are eliminated. The simulation section of this paper consists of a case study based on a fuzzy logic-controlled PWM inverter in which the performance of the developed fuzzy logic controller is evaluated.

Supplemental LED lighting increases pansy growth

Pansy (Viola cornuta) is a facultative long-day plant that flowers from October until March in Turkey. During the winter months, low light levels can limit plant growth and development. Light emitting diodes (LEDs) can provide supplemental lighting in greenhouses which produce same light intensity with less energy than conventional incandescent lighting. Light emitting diode technologies have enabled affordable and efficient light systems to be installed in greenhouses and plastic tunnels in the field. In this experiment we evaluated the effects of supplemental red-orange LED lightening on the growth and development of pansy cv. Blue Blotch grown in plastic tunnels. The energy, which LEDs are to consume, was provided through a solar panel system with the aim of drawing attention to the cleanliness of solar energy source. Five hours of supplement LED lighting was applied after dusk starting from November to February. Pansy growth and development parameters were compared with non-light supplied control plants. Supplemental LED lighting significantly increased plant biomass weight, flower number and leaves number at the rate of 52%, 72%, and 47%, respectively. Moreover, LED lighting increased plant growth rate (0.109 and 0.306 g of fresh weight), compared with the no light control. LED lighting, however, had no effect on length of stems, number of branches and the diameter of flowers. Thus, this study indicated that pansies are light limited during the winter months and supplemental LED lighting can significantly increase pansy growth and development.

Experimental architecture of a DSP based signal generation for PWM inverter

This article presents the analysis and design of an experimental study on the implementation of digital signal processor (DSP) controlled single‐phase pulse width modulation (PWM) inverter based on Simulink and Real Time Workshop in Matlab. Each stage of PWM signal generation using DSP is comprehensively presented to ease the design and analysis of complicated control algorithms in DSP based solutions. The article also enhances knowledge more about experimental studies in the laboratory. The performance of the DSP based PWM inverter design is analyzed through simulation studies under various switching frequencies and the theoretical considerations are successfully validated with experimental prototype based on TMS320F2812 DSP.

Fotovoltaik (FV) Teknolojileri, FV Modül Karakteristiği, Bağlantı Formları ve Standartların İncelenmesi

Son yillarda enerjinin etkin kullanimi, nufus artisi ve sanayilesme ile birlikte hizla artan enerji talebine bagli olarak cok onemli hale getirmistir. Enerji kullaniminda artan talebe paralel olarak dunya geneli enerji arzi cok buyuk baskiya maruz kalmaktadir. Bu nedenle enerji verimliligi ve alternatif enerji kaynaklarinin kullanilmasi cok onemli bir konu haline gelmistir. Fotovoltaik sistemler (FV) en cok kullanilan alternatif enerji kaynaklari arasinda gosterilebilir ve bu teknoloji gun gectikce dikkat cekici populerlik kazanmaktadir. Fakat, FV sistemler dusuk verimlilik, yuksek kurulum maliyeti ve degisken atmosferik kosullardan negatif olarak etkilenmektedirler. Son zamanlarda calismalar kullanilan hammaddeleri modifiye ederek FV panellerin yapisal verimliligini artirmak ve enerji verimliligi cozumleri saglamak amaciyla genisletilmistir. Bu yazida FV hucre teknolojisi uzerine kullanilan hammadeler baz alinarak verimlilik, fiyat ve teknik ozellikler acisindan inceleme yapilmasi amaclanmistir. Ote yandan panel karakteristigi cikarimi ve guc sistemlerinin benzetiminde kullanmak icin PSCAD/EMTDC programi kullanilarak FV panel modeli sunulmustur. Bu panel modeli hem sebeke baglantili FV sistemlerin hemde sebekeden bagimsiz sistemlerin guc sistem dinamigi ve gecici durum analizi cikarimi icin uygundur. Ayrica Turkiye icin sebekeye baglanti sartlari ve baz alinan sartnamelerin detayli incelenmesi.

Üniversite Hastanesinde Enerji Verimliliğini Artıran Uygulamaların Geri Dönüşüm Sürelerinin Hesaplanması

Artan enerji talebi ve mevcut fosil yakit tabanli kaynaklarinin hizla tukenmesi, ulkelerin enerjiyi verimli kullanmasina, enerji tasarrufu yapmasina ve alternatif enerji kaynaklarini aramasina zorlamistir. Enerji ihtiyaclarini karsilamada baska ulkelere bagimli olan bizim gibi gelismekte olan ulkelerde, mevcut enerjiyi verimli kullanmak ve tasarruf calismalari yapmak daha buyuk onem tasimaktadir. Hastaneler binalarda kullanilan toplam enerjinin yaklasik olarak %6’sini tuketmektedir. Isitma, Havalandirma ve Iklimlendirme sistemleri (IHIS), hastanede tuketilen elektrik enerjisinin buyuk bir kismini olusturmaktadir. Iklimlendirme sistemleri toplam tuketilen yaklasik olarak %70’inden sorumludur. Hastanedeki elektrik motorlari ve aydinlatma sistemleri yaklasik olarak toplam enerjinin %19-21‘lik kismini harcamaktadirlar. Bu calismada, aydinlatma cihazlari, elektrik motorlari ve IHIS sistemleri uzerine yapilan detayli calismalar sonucunda, bir universite hastanesinde bu cihazlarinenerji tasarruf potansiyelleri ve geri donusum sureleri tahmin edilmistir