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Golestan S.,Islamic Azad University at Abadan | Monfared M.,Ferdowsi University of Mashhad | Freijedo F.D.,Gamesa Innovation and Technology | Guerrero J.M.,University of Aalborg
IEEE Transactions on Power Electronics

A phase-locked loop (PLL) is a closed-loop feedback control system, which synchronizes its output signal in frequency as well as in phase with an input signal. The phase detector, the loop filter, and the voltage controlled oscillator are the key parts of almost all PLLs. Within the areas of power electronics and power systems, which are focused on in this paper, the PLLs typically employ a proportional-integral controller as the loop filter, resulting in a type-2 control system (a control system of type-N has N poles at the origin in its open-loop transfer function). Recently, some attempts have been made to design type-3 PLLs, either by employing a specific second-order controller as the loop filter, or by implementing two parallel tracking paths for the PLL. For this type of PLLs, however, the advantages and limitations are not clear at all, as the results reported in different literature are contradictory, and there is no detailed knowledge about their stability and dynamic characteristics. In this paper, different approaches to realize a type-3 PLL are examined first. Then, a detailed study of dynamics and analysis of stability, followed by comprehensive parameters design guidelines for a typical type-3 PLL are presented. Finally, to get insight into the advantages/ limitations of this type of PLLs, the performance of a well-tuned type-3 PLL is compared with a conventional synchronous reference frame PLL (which is a type-2 PLL) through extensive experimental results and some theoretical discussions. © 1986-2012 IEEE. Source

Golestan S.,Islamic Azad University at Abadan | Monfared M.,Ferdowsi University of Mashhad | Freijedo F.D.,Gamesa Innovation and Technology
IEEE Transactions on Power Electronics

In grid-connected applications, the synchronous reference frame phase-locked loop (SRF-PLL) is a commonly used synchronization technique due to the advantages it offers such as ease of implementation and robust performance. Under ideal grid conditions, the SRF-PLL enables a fast and accurate phase/frequency detection; however, unbalanced and distorted grid conditions highly degrade its performance. To overcome this drawback, several advanced PLLs have been proposed, such as the multiple reference frame-based PLL, the dual second-order generalized integrator-based PLL, and the multiple complex coefficient filter-based PLL. In this paper, a comprehensive design-oriented study of these advanced PLLs is presented. The starting point of this study is to derive the small-signal model of the aforementioned PLLs, which simplifies the parameter design and the stability analysis. Then, a systematic design procedure to fine tune the PLLs parameters is presented. The stability margin, the transient response, and the disturbance rejection capability are the key factors that are considered in the design procedure. Finally, the experimental results are presented to support the theoretical analysis. © 1986-2012 IEEE. Source

Bakhtiari S.,Islamic Azad University at Abadan
Advances in Information Sciences and Service Sciences

Currently, with the emergence of mobile payment systems and service-oriented architecture, the focus has shifted to utilizing modern service industry in mobile commerce. One of the important uses of mobile applications is transforming the mobile phone into a mobile wallet with digital cash that supports both anonymity (as real cash) and security [3]. Hence, in this article we propose applying service-oriented architecture in a mobile payment system called Mobi Cash [17] to provide fully anonymity for mobile users. Source

Golestan S.,Islamic Azad University at Abadan | Monfared M.,Ferdowsi University of Mashhad | Freijedo F.D.,Gamesa Innovation and Technology | Guerrero J.M.,University of Aalborg | Guerrero J.M.,University of Barcelona
IEEE Transactions on Industrial Electronics

Control Parameters design of a three-phase synchronous reference frame phase locked loop (SRF-PLL) with a prefiltering stage (acting as the sequence separator) is not a trivial task. The conventional way to deal with this problem is to neglect the interaction between the SRF-PLL and prefiltering stage, and treat them as two separate systems. This approach, although very simple, is not optimum as the prefiltering stage and the SRF-PLL may have comparable dynamics. The aim of this paper is to develop a systematic and efficient approach to design the control parameters of the SRF-PLL with prefiltering stage. To this end, the paper first optimizes the performance of the prefiltering stage in detection of the sequence components. The paper then proceeds to reduce the interaction between the prefiltering stage and SRF-PLL, which is achieved by employing a derivative-filtered proportional-integral-derivative controller as the loop filter (instead of the commonly adopted proportional-integral controller) and arranging a pole-zero cancellation. The suggested method is simple and efficient, and is applicable to the joint operation of different sequence separation techniques and the SRF-PLL. The effectiveness of the suggested design approach is confirmed through extensive experimental results. © 1982-2012 IEEE. Source

Monfared M.,Ferdowsi University of Mashhad | Golestan S.,Islamic Azad University at Abadan
Renewable and Sustainable Energy Reviews

Small-scale renewable energy sources, such as small hydro turbines, roof-mounted photovoltaic and wind generation systems, and commercially available fuel cells are usually connected to the single-phase distribution grid through a voltage source converter. To regulate the power exchange with the single-phase grid, and at the same time, reduce the harmonic distortions in the ac current, different current control structures have already been proposed, among which the current hysteresis control, the voltage oriented control, and the proportional-resonant based control have found more attentions. This paper provides an overview of the main characteristics of these control strategies. Also, some implementation aspects such as the fictitious signal generation and the single-phase grid synchronization techniques are discussed. Finally, through extensive simulations a comparative study of the presented control strategies is presented. The simulations are supported by experiments. © 2012 Elsevier Ltd. All rights reserved. Source

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