A robust SVM technique to minimize the effects of unbalanced voltage disturbances

6th International Conference on Electrical and Electronics Engineering, ELECO 2009 --5 November 2009 through 8 November 2009 -- Bursa --Space vector modulation (SVM) is one of the most popular PWM techniques in the control methods of multilevel inverters. The assignment of the reference vector location is very important to obtain the exact switching times and to determine the correct space vectors in this technique. The location of the reference vector is determined by utilizing the phase angle of the system. It can be obtained from Clarke Transformation for SVM technique or phase-locked loop (PLL) for other methods. The unbalanced disturbances occurred in the three-phase systems affect the switching times obtained by utilizing the phase angle. The output waveform of the multilevel inverters is affected as well. In this study, the effects of disturbances such as line to line faults, unbalanced voltage sags/swells are investigated on conventional SVM technique. In order to minimize these affects, a new technique based on Clarke Transformation is proposed and applied to the two-level inverter. PSCAD/EMTDC simulation program is used to apply the case studies and to take the simulation results

Simulation study of fuzzy based unified power flow controller on power flow controlling

2008 Int. Symposiums on Electronic Commerce and Security (ISECS);IEEE SMC;IEEE Computer Society;Institute of Electrical and Electronics Engineers;Guangdong University of Business Studies2008 Workshop on Power Electronics and Intelligent Transportation System, PEITS 2008 --4 August 2008 through 5 August 2008 -- Guangzhou --Unified Power Flow Controller (UPFC) is the most widely used FACTS device to control the power flow and to optimize the system stability in the transmission line. The controller used in the control mechanism has an important effect on the performance of UPFC. According to this, the performance of UPFC for several case studies was observed by using different control mechanisms based on Proportional-Integral (PI) and fuzzy controllers in this study. Fuzzy Logic Controller (FLC) was developed by using Takagi-Sugeno inference system and used in UPFC. The case studies are applied to prove the capability of UPFC on power flow and the effectiveness of controllers on the performance of UPFC at the different operating conditions. PSCAD/EMTDC program is used to model UPFC and to verify the performance of UPFC with different controllers in the transmission line. © 2008 IEEE

Artificial neural network-based discrete-fuzzy logic controlled active power filter

Artificial neural network (ANN) is a computational algorithm based on the structure and functions of biological neural networks. It is used for modelling of the non-linear systems that cannot be mathematically expressed by the formula and extraction of the system dynamics, expressed by using the complex mathematical equations, such as harmonics. To show the effective usage of ANNs in the power system, the fundamental harmonic of a load with six-pulse thyristor controlled rectifier is extracted with ANN by using the system variables that are difficult to express with each other. Then, a new approach is proposed to generate the reference signal for compensating the harmonics of the current by using discrete fuzzy logic in this study. In addition, a simple and useful method to determine the circuit parameters of the active power filter (APF) is proposed to reduce the rating of the required filter and the capacitor values without affecting its efficiency. Case studies are performed to test the performance of the proposed control algorithm for APF. © The Institution of Engineering and Technology 2014

Vector-based reference location estimating for space vector modulation technique

Space vector modulation (SVM) has become a popular pulse width modulation technique (PWM) for multilevel inverters. In SVM technique, the determination of the angular position of the reference voltage vector is very important to generate the required output voltage by the inverter. The switching time and switching sequence of SVM are calculated by vector location. The calculation of vector location and switching time become difficult and more complex when the numbers of output voltage levels increase for a given number of inverter levels. In this paper, a new SVM method is developed to determine the actual vector location. The proposed method can increase RMS value of the inverter output voltage; can reduce the algorithm complexity and computation time when compared to conventional SVM methods. In addition, the calculation of switching times for two-level inverter is generalized for N-level inverters. PSCAD/EMTDC simulation program is used to create the test system and to perform the case studies. Extensive simulation results are given to validate the performance of the proposed algorithm. © 2011 Elsevier B.V. All rights reserved

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. © 2011 IEEE

Multi-functional static synchronous compensator for distribution systems [Dagitim sistemleri için çok fonksiyonlu statik senkron kompanzatör]

Power quality problems cause the damage and inefficient operation of the electronic devices and sensitive loads, and lead to substantial economic losses. In order to eliminate these problems, Distribution Static Synchronous Compensator (D-STATCOM) is widely used due to the fast response to the changes in the system dynamics and the capability of controlling the power system parameters. In this research study, D-STATCOM, having a control method based on General Wavelet Transform, is firstly introduced and the balanced/unbalanced voltage fluctuations, current/voltage harmonics and reactive power that are most common types of power quality problems in the distribution systems are simultaneously compensated. With this study, it is the first time to formulate the general wavelet algorithm as mathematically in the literature. The performance of the proposed method is tested with several case studies by using PSCAD/EMTDC program

Dynamic control of unified power flow controller under unbalanced network conditions

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. © 2010 Published by Elsevier B.V. All rights reserved

A Review on Feature Extraction for Speaker Recognition under Degraded Conditions

Speech is a signal that includes speaker's emotion, characteristic specification, phoneme-information etc. Various methods have been proposed for speaker recognition by extracting specifications of a given utterance. Among them, short-term cepstral features are used excessively in speech, and speaker recognition areas because of their low complexity, and high performance in controlled environments. On the other hand, their performances decrease dramatically under degraded conditions such as channel mismatch, additive noise, emotional variability, etc. In this paper, a literature review on speaker-specific information extraction from speech is presented by considering the latest studies offering solutions to the aforementioned problem. The studies are categorized in three groups considering their robustness against channel mismatch, additive noise, and other degradations such as vocal effort, emotion mismatch, etc. For a more understandable representation, they are also classified into two tables by utilizing their classification methods, and used data-sets. © 2017 IETE

Real-Time Speaker Independent Isolated Word Recognition on Banana Pi

10th International Conference on Electronics, Computers and Artificial Intelligence, ECAI 2018 --28 June 2018 through 30 June 2018 -- --Devices controlled with voice commands have gained popularity over the last decade. To recognize an utterance, they usually require an internet connection, or use commercial programming libraries. Therefore, their flexibility is low, and algorithm update opportunities are limited. In this study, a speaker independent isolated word recognition algorithm, embedded in a single board computer, is proposed to recognize utterances in realtime. The proposed system neither requires an internet connection, nor uses external libraries. Mel Frequency Cepstral Coefficients and their deltas are used as feature vectors. Gaussian mixture models are utilized to define word models. Digits and some confirmation words of Turkish language are recorded ten times in one session from twenty-four individuals. Seven of these records are used for training, and the others for testing the system. The off-line experimental results showed that the system is working with 99.98%. In real-time experiments, the system's recognition accuracy was proficient for controlled environments. © 2018 IEEE.17103031ACKNOWLEDGMENT This work was supported by Adana Science and Technology SRU under project number 17103031

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 fi rst 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