Ahmet Gani

A performance comparison of static VAr compensator based on Goertzel and FFT algorithm and experimental validation

The main objective of the present paper is to introduce a new approach for measuring and calculation of fundamental power components in the case of various distorted waveforms including those containing harmonics. The parameters of active, reactive, apparent power and power factor, are measured and calculated by using Goertzel algorithm instead of fast Fourier transformation which is commonly used. The main advantage of utilizing Goertzel algorithm is to minimize computational load and trigonometric equations. The parameters measured in the new technique are applied to a fixed capacitor–thyristor controlled reactor based static VAr compensation system to achieve accurate power factor correction for the first time. This study is implemented both simulation and experimentally.

Speed control of induction motor based on model reference adaptive control

In recent years, adaptive and intelligent control schemes have begun to take the place of conventional control methods. In this study, a model reference adaptive control (MRAC) scheme based on genetic algorithm (GA) and Fuzzy Logic (FL) has been used by the help of Vector Control type driving method based on Space Vector Pulse Width Modulation (SVPWM). In this control technique, the conventional PI controller and the proposed control strategy has been applied to induction motor in real conditions by using an appropriate digital signal processor and peripheral units. As digital processor, DSPIC 30F6010 which is produced by Microchip Co. has been used. Experimental studies have been implemented for both of the control techniques under the same conditions. The results obtained from conventional PI controller and the proposed control strategy have been analysed and compared.

Robust control of shunt active power filter using interval type-2 fuzzy logic controller for power quality improvement

Original scientific paper It is well-known that shunt active power filter (SAPF) is widely used to reduce harmonic distortion and to compensate reactive power in electrical power systems. DC bus voltage control of SAPF is very important for excellent power quality. In the control of SAPF, DC bus voltage is controlled by conventional control methods such as PI and PID controllers. However, these controllers cannot give good results under transient and steady state conditions. Robust and intelligent controllers are required in order to improve performance of SAPF. In this paper, interval type-2 fuzzy logic system (T2FLS) that does not require mathematical model to be controlled system is preferred for control of DC bus voltage of SAPF and compared with type-1 fuzzy logic system (T1FLS). SAPF structures with both controllers are designed and simulated using MATLAB /Simulink environment. Simulation results have shown that SAPF structure with proposed controller has superior features than T1FLS in terms of fixed DC bus voltage, total harmonic distortion and power quality.

Power Quality Improvement Using Hybrid Passive Filter Configuration for Wind Energy Systems

Wind energy conversion systems (WECS) which consist of wind turbines with permanent magnet synchronous generator (PMSG) and full-power converters have become widespread in the field of renewable power systems. Generally, conventional diode bridge rectifiers have used to obtain a constant DC bus voltage from output of PMSG based wind generator. In recent years, together advanced power electronics technology, Pulse Width Modulation (PWM) rectifiers have used in WECS. PWM rectifiers are used in many applications thanks to their characteristics such as high power factor and low harmonic distortion. In general, L, LC and LCL-type filter configurations are used in these rectifiers. These filter configurations are not exactly compensate current and voltage harmonics. This study proposes a hybrid passive filter configuration for PWM rectifiers instead of existing filters. The performance of hybrid passive filter was tested via MATLAB/Simulink environment under various operational conditions and was compared with LCL filter structure. In addition, neuro-fuzzy controller (NFC) was preferred to increase the performance of PWM rectifier in DC bus voltage control against disturbances because of its robust and nonlinear structure. The study demonstrates that the hybrid passive filter configuration proposed in this study successfully compensates current and voltage harmonics, and improves total harmonic distortion and true power factor.

Improved control configuration of PWM rectifiers based on neuro-fuzzy controller.

It is well-known that rectifiers are used widely in many applications required AC/DC transformation. With technological advances, many studies are performed for AC/DC converters and many control methods are proposed in order to improve the performance of these rectifiers in recent years. Pulse width modulation (PWM) based rectifiers are one of the most popular rectifier types. PWM rectifiers have lower input current harmonics and higher power factor compared to classical diode and thyristor rectifiers. In this study, neuro-fuzzy controller (NFC) which has robust, nonlinear structure and do not require the mathematical model of the system to be controlled has been proposed for PWM rectifiers. Three NFCs are used in control scheme of proposed PWM rectifier in order to control the dq-axis currents and DC voltage of PWM rectifier. Moreover, simulation studies are carried out to demonstrate the performance of the proposed control scheme at MATLAB/Simulink environment in terms of rise time, settling time, overshoot, power factor, total harmonic distortion and power quality.

Performance analysis and design of robust controller for PWM rectifier

In this paper, a new controller has been proposed for pulse width modulation (PWM) based rectifiers. Control scheme of proposed PWM rectifier is used two Neuro-Fuzzy Controllers (NFC) which has robust and nonlinear structure in order to control the reactive power and DC voltage of PWM rectifier. Thus, reactive power and DC voltage are controlled effectively. Moreover, simulation studies are carried out to test the performance of the proposed control scheme at Matlab/Simulink environment. The simulation results obtained from the proposed control scheme are not only superior in the rise time, settling time and overshoot but have high power factor, lower total harmonic distortion (THD) and good power quality.

Isıl İşlem Uygulamalarında Kullanılan Bir Karışım Tankının Bulanık Mantık Esaslı Denetimi

Karisim tanklarinin kontrolu, gida sanayi, tarimsal ilaclama, tekstil, atik su aritma, sut uretimi, nukleer enerji uretimi, petrokimya endustrisi, kimyasal surecler ve ilac sanayi gibi endustriyel uygulamalar icin cok onemlidir. Bu calismada cok girisli cok cikisli ve dogrusal olmayan bir sistem olan sivi karisim tankinin kontrolu, MATLAB/Simulink benzetim programi ile yapilmistir. Bu karisim tankina iki pompa vasitasiyla sicak ve soguk su akisi saglanmaktadir. Suyun akis miktari valfler ile kontrol edilerek, tankta istenilen su sicakligi ve seviyesi elde edilmektedir. Kontrol sistemi, karisim tanki icindeki suyun seviye ve sicakligini istenilen degerlerde tutmak amaciyla iki bagimsiz bulanik mantik denetleyiciden olusmaktadir

Farklı Kural Tabanları Kullanarak PI-Bulanık Mantık Denetleyici ile Doğru Akım Motorunun Hız Denetim Performansının İncelenmesi

Dogru akim (DA) motorlari kolay denetlenmeleri ve yuksek performans gibi ozelliklerinden dolayi endustride konum ve hiz denetimi uygulamalarinda sikca kullanilmaktadir. Dogru akim motorlarinin hiz denetiminde bulanik mantik esasli denetim yaygin olarak kullanilmaktadir. Bulanik mantik esasli denetimin, geleneksel denetim yontemleri ile elde edilen sonuclardan daha ustun oldugunu bircok uygulama gostermektedir.Bu calismada, dogru akim motorunun hiz denetimi icin bir PI-bulanik mantik denetleyici tasarlanmistir.Tasarlanan PI-bulanik mantik denetleyicide tek kural tabani yerine degisik yapilardaki kural tabanlari kullanilarak ayni kosullar altinda performanslarinin karsilastirilmasi yapilmistir. Benzetim calismalari MATLAB/Simulink’te gerceklestirilmistir.

Farklı Bulanık Üyelik Fonksiyonları Kullanarak Doğrusal Olmayan Yük Etkisindeki Doğru Akım Servo Motorun Hız Denetimi

Almost none of the systems is not linear in real life. Fuzzy logic control has emerged as an alternative approach with non-linear methods. Non-linear characteristics of the systems are represented by membership functions, fuzzy rule base and fuzzy inference process. The systems that contain non-stationary, energy storage elements and system parameters that vary depending on the state variable are non-linear dynamic systems. Control applications of dynamic systems are difficult to realize because dynamic systems have usually non-linear structure. Fuzzy logic based controllers that have the ability with non-linear conversion capabilities are successful control applications of such systems. The performance of this controller can be increased by treating the method used at the design stage. In this study, fuzzy logic based controller that is improved nonlinear model of dc servo motor for speed control by using different fuzzy membership functions will be investigated on the system performance.