Extraction of voltage harmonics using multi-layer perceptron neural network

This paper presents a harmonic extraction algorithm using artificial neural networks for Dynamic Voltage Restorers (DVRs). The suggested algorithm employs a feed forward Multi Layer Perceptron (MLP) Neural Network with error back propagation learning to effectively track and extract the 3rd and 5th voltage harmonics. For this purpose, two different MLP neural network structures are constructed and their performances compared. The effects of hidden layer, supervisors and learning rate are also presented. The proposed MLP Neural Network algorithm is trained and tested in MATLAB program environment. The results show that MLP neural network enable to extract each harmonic effectively. © 2007 Springer-Verlag London Limited

Sequence reference frame-based new sag/swell detection method for static transfer switches

A fast synchronous reference frame (SRF)-based sag/swell detection method for static transfer switches (STSs) is proposed. In the proposed method, the positive sequence d-q components are passed through a differentiator. The resulting values are then crisscrossed with the positive sequence d-q components and calculated to extract the original positive sequence components. The obtained original positive sequence d component is used as an ideal error signal to generate the transfer signal. This improves the response time of sag/swell detection with respect to conventional methods. Simulation studies using the PSCAD/EMTDC software program confirm the improvement. © 2009 The Institution of Engineering and Technology

Overview of an extended custom power park

2008 IEEE 2nd International Power and Energy Conference, PECon 2008 --1 December 2008 through 3 December 2008 -- Johor Baharu --The increasing concern about the quality and reliability of electric power has increased in continued growth in the application of Custom Power (CP) devices. The integration of multiple CP Devices in an industrial/commercial park is called as Custom Power Park (CPP). The proposed park is superior to the conventional CPP because the park improves both the current and voltage quality of linear and nonlinear loads using Dynamic Voltage Restorer (DVR), Active Power Filter (APF), Static Transfer Switch (STS) and backup generator. This paper presents the simulation results of an extended CPP using PSCAD simulation package and the operation of the CPP control center in detail. © 2008 IEEE

A novel switching signals generation method for hybrid multilevel inverters

6th International Conference on Electrical and Electronics Engineering, ELECO 2009 --5 November 2009 through 8 November 2009 -- Bursa --Use of multilevel inverters is becoming more popular in the recent years. Various topologies and modulation methods have been reported for utility and drive applications in the recent literature. Hybrid multilevel structures are the new multilevel inverter topologies where the cascaded series inverters have different internal DC bus voltages and/or modulated quite differently. This paper introduces a novel switching signals generation (modulation) method for hybrid multilevel inverters. This method is new and based on reference signal tracking. The structure of modeled hybrid multilevel inverter and operating principles of the proposed method are presented. The proposed method is verified by computer simulations using PSCAD/EMTDC. The waveform and THD values are presented and analyzed, which prove the validity of the proposed method

Computer simulation and experimental implementation of a PIC-controlled hybrid multilevel inverter for undergraduate laboratories

Hybrid multilevel inverters have emerged as attractive power conversion systems at medium voltage levels, which are structured by cascaded series inverters having different internal DC bus voltages. This scheme therefore provides the capability to produce higher voltages at higher speeds with low switching losses and high conversion efficiency. The fundamentals and importance of hybrid multilevel systems can be easily enhanced by the undergraduate with visual learning and laboratory studies. However, the students cannot be able to implement the peripheral interface controller (PIC)-based projects sufficiently. In this paper, the simulation models and experimental setup of a hybrid multilevel inverter are presented in detail. From the theoretical and experimental experience obtained from this study, the students and engineers can provide more analytical opportunities for studying control algorithms of PIC controlled power electronics projects. This will provide the students to reinforce their lectures and laboratory studies. © 2010 Wiley Periodicals, Inc

Performance comparison of PWM methods for 27-level hybrid multilevel inverters

Multilevel inverters have become more popular due to reduced switching losses, low costs, low harmonic distortion and high-voltage capability when compared to traditional PWM inverters. A new family of multilevel inverters that has decreased the number of separated DC sources has emerged named as hybrid multilevel inverter. In this study, theories and applications of four PWM modulation methods for 27 level hybrid multilevel inverters are examined. The comparative case studies are presented to validate the examined modulation technique through harmonic spectrum analysis, output voltage magnitude, THD, WTHD and simulation using Power System Computer Aided Design Program (PSCAD)

Power quality improvement with an extended custom power park

This paper describes the operation principles of an extended custom power park (CPP). The proposed park is more effective when it is compared to the conventional power parks regarding the yield of improving both current and voltage quality of linear and nonlinear loads using dynamic voltage restorer (DVR), active power filter (APF), static transfer switch (STS) and diesel generator (DG). Moreover, a supervisory power quality control centre is presented to coordinate these custom power (CP) devices by providing pre-specified quality of power. A fast sag/swell detection unit is also presented to improve the system response. The ability of the extended CPP for power quality improvements is further analyzed using PSCAD/EMTDC through a set of simulation tests. © 2009 Elsevier B.V. All rights reserved.EEEAG-106E188The authors would like to acknowledge Electrical, Electronics and Informatics Research Group of the TUBITAK (Project No: EEEAG-106E188) for full financial support. Appendix A A.

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

OPEN unified power quality conditioner with control based on enhanced phase locked loop

OPEN unified power quality conditioner (UPQC) offers different power quality levels with different electricity bill to their users. OPEN UPQC has more flexible modularity than traditional UPQC for field applications. OPEN UPQC consists of two controlled pulse-width modulated shunt and series inverters that have no common DC link. Shunt inverter eliminates current harmonics originating from non-linear load side and series inverter mitigates voltage sag/swell at the point of common coupling caused from faults on transmission system. In this study, controllers for both shunt and series inverters are based on enhanced phase locked loop (E-PLL) and non-linear adaptive filter. For the controller of shunt inverter, proportional integrator controller-based DC-link control strategy is adapted to E-PLL. A fast sag/swell detection method is also presented. Functionalities of OPEN-UPQC system is deeply analysed and tested through simulation studies with power system computer aided design/electromagnetic transients DC analysis program. The test results verify that OPEN UPQC achieves good performance for mitigating the effects of voltage sag/swell and suppressing the load current harmonics. ©The Institution of Engineering and Technology 2013

Experimental and simulation based study of an adaptive filter controlled solid state transfer switch

The most common power quality problems in electrical distribution systems are related to single phase to ground faults causing unbalanced voltage sags. One of the most widely used methods for sag detection is conventional method based on d–q transformation. However, this method has the disadvantage of missing the detection of single phase-to-ground faults, because this method uses a voltage sag level signal obtained from the average of three phase voltages for sag detection. In this paper, an adaptive filter based sag detection method is proposed for solid state transfer switch (SSTS). Simulation models of the SSTS using the adaptive filter based proposed and d–q transformation based methods are developed by PSCAD/EMTDC program. Simulation results show that, the SSTS using proposed method is able to detect three phases and/or single phase voltage sags, correctly. To validate the simulation model and results, a three-phase experimental SSTS prototype is successfully constructed and experimental results are presented. © 2014, Springer-Verlag Berlin Heidelberg