Engin Ozdemir

Synchronous-Reference-Frame-Based Control Method for UPQC Under Unbalanced and Distorted Load Conditions

This paper presents a new synchronous-reference-frame (SRF)-based control method to compensate power-quality (PQ) problems through a three-phase four-wire unified PQ conditioner (UPQC) under unbalanced and distorted load conditions. The proposed UPQC system can improve the power quality at the point of common coupling on power distribution systems under unbalanced and distorted load conditions. The simulation results based on Matlab/Simulink are discussed in detail to support the SRF-based control method presented in this paper. The proposed approach is also validated through experimental study with the UPQC hardware prototype.

Fundamental-Frequency-Modulated Six-Level Diode-Clamped Multilevel Inverter for Three-Phase Stand-Alone Photovoltaic System

This paper presents a fundamental-frequency-modulated diode-clamped multilevel inverter (DCMLI) scheme for a three-phase stand-alone photovoltaic (PV) system. The system consists of five series-connected PV modules, a six-level DCMLI generating fundamental-modulation staircase three-phase output voltages, and a three-phase induction motor as the load. In order to validate the proposed concept, simulation studies and experimental measurements using a small-scale laboratory prototype are also presented. The results show the feasibility of the fundamental frequency switching application in three-phase stand-alone PV power systems.

A novel adaptive hysteresis band current controller for shunt active power filter

In this paper, a novel adaptive hysteresis band current controller is proposed for active power filter to eliminate harmonics and to compensate the reactive power of three-phase rectifier. The novel adaptive hysteresis band current controller changes the hysteresis bandwidth according to modulation frequency, supply voltage, DC capacitor voltage and slope of the i/sub c//sup */ reference compensator current wave. The hysteresis band current controller determines the switching signals of the active power filter (APF), and the algorithm based on an extension of synchronous reference frame theory (d-q-0) is used to determine the suitable current reference signals. The results of simulation study of new APF control technique presented in this paper is found quite satisfactory to eliminate harmonics and reactive power components from utility current. All of these studies have been carried out through detail digital dynamic simulation using the Matlab simulink power system toolbox. The APF is found effective to meet IEEE 519 standard recommendations on harmonics levels.

Elimination of Harmonics in a Five-Level Diode-Clamped Multilevel Inverter Using Fundamental Modulation

In this study, elimination of harmonics in a five- level diode-clamped multilevel inverter (DCMLI) has been implemented by using fundamental modulation switching. The proposed method eliminates harmonics by generating negative harmonics with switching angles calculated for selective harmonic elimination method. In order to confirm the proposed method, first Matlab/Simulink and PSIM simulation results are given. Then the proposed method is also validated by experiments with Opal-RT controller and a 10 kW three- phase, five-level DCMLI prototype.

Fundamental frequency modulated multilevel inverter for three-phase stand-alone photovoltaic application

This paper presents a fundamental frequency modulated multilevel inverter scheme for use with a three-phase stand-alone photovoltaic (PV) system. The system consists of four series connected PV arrays, a five-level diode-clamped multilevel inverter (DCMLI) generating fundamental modulation staircase three-phase output voltages, and a three-phase induction motor as the load. In order to validate the proposed concept, simulation studies and experimental measurements, done using a small-scale laboratory prototype, are also presented. The results show the feasibility of the fundamental switching application in three- phase stand-alone PV power systems.

Real time monitoring of tool wear using multiple modeling method

Real time monitoring of tool wear in machining operations is very crucial in order to prevent tool failures, increase machine utilization and decrease production cost in an automated manufacturing environment. In general the price of the tool is relatively low, but the failure can cause incomparably higher production cost. Over the years, a wide variety of tool condition monitoring (TCM) techniques has been developed based on sensor signals such as cutting forces, acoustic emission and vibration. In this paper, a real time monitoring technique based on multiple modeling method is presented for drilling operations which is one of the most widely used manufacturing operations. The multiple modeling method utilizes cutting forces (thrust and torque) collected during the drilling operation and classifies these forces using hidden Markov models (HMM) to determine wear status of the drill bit. Experimental results have been presented in order to demonstrate the effectiveness of the proposed method.

A novel control method for unified power quality conditioner (UPQC) under non-ideal mains voltage and unbalanced load conditions

This paper presents a new control method to compensate the power quality problems through a three-phase unified power quality conditioner (UPQC) under non-ideal mains voltage and unbalanced load conditions. The performance of proposed control system was analyzed using simulations with Matlab/Simulink program, and experimental results with the hardware prototype. The proposed UPQC system can improve the power quality at the point of common coupling (PCC) on power distribution system under non-ideal mains voltage and unbalanced load conditions.

The Design and Implementation of a Shunt Active Power Filter based on Source Current Measurement

In this study, design and implementation of a shunt active power filter (APF) based on a simplified control method is given without load and filter current measurement. The proposed simplified control method is based on instantaneous reactive power theory (IRP) and requires only measuring the source currents to reduce the number of current sensors (CSs) required in the conventional control approach. The source currents are exactly in phase with the line voltages and approximately in sinusoidal waveform after reactive power and harmonic compensation. The proposed control technique has been tested under different load conditions using Matlab/Simulink simulations and validated with a 10 kVA/380 V experimental prototype based on digital signal processor (DSP) TMS320F2812. Both simulation and experimental test results demonstrate that the proposed method is feasible in meeting the IEEE 519-1992 recommended harmonic standard limits.

A Simplified Control Algorithm for Shunt Active Power Filter Without Load and Filter Current Measurement

In this study, a new control algorithm for three-phase shunt active power filter (APF) is proposed without load and filter current measurement. The proposed control method, based on instantaneous reactive power (IRP) theory, requires only measuring the source currents in order to reduce the number of current sensors (CSs) required in the conventional control approach. The source currents are exactly in phase with the line voltages and approximately sinusoidal waveform after compensation. The proposed control technique has been simulated Matlab/Simulink and tested under thyristor bridge rectifier load condition, and validated with a 10 kVA/380 V experimental prototype based on digital signal processor (DSP) TMS320F2812. Both simulation and experimental test results demonstrate viability of the proposed method, successful in meeting the IEEE 519-1992 recommended harmonic standard limits

An analysis of three-phase four-wire active power filter for harmonic elimination reactive power compensation and load balancing under nonideal mains voltage

This paper presents a new control algorithm for a three-phase four-wire active power filter (APF) to eliminate harmonics, to compensate reactive power and neutral currents and to balance load currents of mixing single-phase and three-phase diode rectifier under non-ideal mains voltage conditions. Three-phase four-wire APF is composed of a conventional three-leg voltage-source inverter (VSI) and split DC link capacitors with a hysteresis-band PWM current controller. MATLAB/SIMULINK power system toolbox is used to simulate the proposed system. The proposed methods performance is compared with conventional instantaneous power (p-q) theory. The simulation results are presented and discussed showing the effectiveness of the control algorithm. The proposed control algorithm is found quite satisfactory to compensate reactive power and neutral current while eliminating harmonics with load balancing under non-ideal mains voltage conditions.