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synchronous-generators
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Introduction Methods for Out-of-Step Protection Of Synchronous Generator
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
Transient stability as one of the power-angle stability parts is a phenomena which is threatening the security of power systems. Following the occurrence of a major disturbance such as a short circuit, each of the generators will be in risk of transient instability due to distance from the fault location. If a generator fails to maintain its stability with the network, it become out-of-step. Out-of-step caused rounding waste of generator rotor and zero average output power. Out-of-step on the one hand lead to severe mechanical and thermal damage to the generator and the other hand disrupt load providing in the power system. So, the instability of the generator must be detected in the...
Enhancement in Frequency Control of Microgrids by Application of Modified Controller in Virtual Synchronous Generator
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
global warming and air pollution due to the excessive consumption of fossil fuels have led to the proliferation of renewable energy sources (RESs). RESs are connected to the grid through power electronic converters and therefore, provide insignificant inertia and damping property for the system. As a result, the system overall inertia and damping is decreased and therefore, the system stability is jeopardized. This thesis presents a comprehensive small signal model for a virtual synchronous generator (VSG) integrated into a microgrid. In the developed state space, active and reactive power control loops of the VSG as well as resistances and reactances of the lines are considered. Based on...
Tuning of novel fractional order fuzzy PID controller for automatic voltage regulator using grasshopper optimization algorithm
, Article Majlesi Journal of Electrical Engineering ; Volume 15, Issue 2 , 2021 , Pages 39-45 ; 2345377X (ISSN) ; Hadi, M. B ; Manthouri, M ; Sharif University of Technology
Islamic Azad University
2021
Abstract
One of the essential pieces of equipment in the power system is the Automatic Voltage Regulator (AVR) or synchronous generator excitation. The system's goal is to maintain the terminal voltage of the synchronous generator at the desired level. AVR is inherently uncertain. Hence, the proposed controller should be able to handle the problem. In this paper, Fractional Order Fuzzy PID (FOFPID) controller has been employed to control the system. To enhance the controller's performance, the Grasshopper Optimization Algorithm (GOA) is used to tune the controller's parameters. Unlike other methods, the FOFPID controller gains are not constant and alter in different operating conditions. The...
Three-phase PFC rectifier with high efficiency and low cost for small PM synchronous wind generators
, Article 7th Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2016, 16 February 2016 through 18 February 2016 ; 2016 , Pages 302-307 ; 9781509003754 (ISBN) ; Tahami, F ; Valipour, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
Small Permanent Magnet Synchronous Generators (PMSG's) are widely used in low power wind turbines. In order to inject the electrical power, generated by PMSG, to the grid, a back-To-back AC/AC power electronic converter is required. In this paper, a novel low cost efficient AC/DC converter is proposed for rectifier stage to obtain the maximum power per ampere of PMSG by using Power Factor Correction method. The new structure is based on DCM SEPIC converter. Reducing the number of semi-conductor switches has decreased converter cost. Additionally, other advantages of this Converter are employing easy control method to obtain the maximum power per ampere and using Synchronous inductance of...
Design, Manufacturing and Testing a Micro Hydro Turbine Governor Using Commercial Controller
, M.Sc. Thesis Sharif University of Technology ; Durali, Mohammad (Supervisor)
Abstract
Lots of micro hydropower potentials are spread all around Iran country. They have the capability to produce electricity for workhouses, residential areas, agricultural and animal husbandries and recreational tourism centers. Hence, Sharif University of Technology and Iran Water and Power Resources Development Corporation decided to design and produce three types of hydro micro turbines to cover all range of micro hydropower potentials available in Iran. These three types of micro turbines are Pelton, Banki and Axial and they are designed in order to cover high, middle and low heads in sequence. Frequency control of micro hydropower plants is so vital due to plant off-grid. The most prevalent...
A new power management control strategy for a MV microgrid with both synchronous generator and inverter-interfaced distributed energy resources
, Article IEEE International Symposium on Industrial Electronics ; 1- 4 June , 2014 , pp. 2529-2534 ; ISBN: 978-147992399-1 ; Hamzeh, M ; Mokhtari, H ; Karimi, H ; Sharif University of Technology
Abstract
Control strategies of a microgrid which includes both synchronous generators and converter-based distribution generation (DG) units must be designed such that effective operation of the microgrid is achieved. The main objective of this paper is to develop a high performance control strategy for an islanded medium voltage (MV) microgrid consisting of inverter and non-inverter interfaced DG units. A new control method for the synchronous generator in an islanded microgrid is proposed based on a virtual droop scheme. The proposed strategy can effectively manage the real and reactive powers of the microgrid among the inverter and non-inverter based DG units. The steady state and dynamic...
Reactive power control of permanent-magnet synchronous wind generator with matrix converter
, Article IEEE Transactions on Power Delivery ; Volume 28, Issue 2 , 2013 , Pages 575-584 ; 08858977 (ISSN) ; Mokhtari, H ; Chang, L ; Sharif University of Technology
2013
Abstract
In this paper, the reactive power control of a variable-speed permanent-magnet synchronous wind generator with a matrix converter at the grid side is improved. A generalized modulation technique based on singular value decomposition of the modulation matrix is used to model different modulation techniques and investigate their corresponding input reactive power capability. Based on this modulation technique, a new control method is proposed for the matrix converter which uses active and reactive parts of the generator current to increase the control capability of the grid-side reactive current compared to conventional modulation methods. A new control structure is also proposed which can...
A novel FRT strategy based on an analytical approach for PMSG-based wind turbines with ESS power rating reduction
, Article Turkish Journal of Electrical Engineering and Computer Sciences ; Volume 26, Issue 5 , 2018 , Pages 2737-2752 ; 13000632 (ISSN) ; Ajami, A ; Mokhtari, H ; Hojabri, H ; Sharif University of Technology
Abstract
In this paper an analytical approach is proposed to formulate the proper set of phase currents reference to ride the permanent magnet synchronous generator (PMSG)-based wind turbine (WT) through faults properly, regardless of fault type. Hence, the WT is forced to inject required reactive current by grid codes together with active power injection, to help support grid frequency during faults and reduce the energy storage system (ESS) power rating. Moreover, it prevents pulsating active power injection to the grid. During grid faults, the DC-link voltage is controlled by the ESS instead of the grid-side converter (GSC) and the GSC controller applies calculated reference currents. The ESS...
A general analytical approach to reach maximum grid support by PMSG-based wind turbines under various grid faults
, Article Journal of Central South University ; Volume 26, Issue 10 , 2019 , Pages 2833-2844 ; 20952899 (ISSN) ; Ajami, A ; Mokhtari, H ; Hojabri, H ; Sharif University of Technology
Central South University of Technology
2019
Abstract
A novel fault ride-through strategy for wind turbines, based on permanent magnet synchronous generator, has been proposed. The proposed strategy analytically formulates the reference current signals, disregarding grid fault type and utilizes the whole system capacity to inject the reactive current required by grid codes and deliver maximum possible active power to support grid frequency and avoid generation loss. All this has been reached by taking the grid-side converter’s phase current limit into account. The strategy is compatible with different countries’ grid codes and prevents pulsating active power injection, in an unbalanced grid condition. Model predictive current controller is...
A low cost front-end converter with maximum power per ampere for rooftop wind turbines
, Article IEEE Access ; Volume 9 , 2021 , Pages 131236-131244 ; 21693536 (ISSN) ; Rezazadeh, G ; Tahami, F ; Ravanji, M. H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Small Permanent Magnet Synchronous Generators (PMSGs) are widely used in small rooftop wind turbines. In order to inject the electric power generated by the PMSG, into the grid, a back-to-back AC/DC/AC converter is required. In this paper, a low cost with high efficiency converter is proposed for the rectifier stage to obtain the maximum power per ampere of PMSG. This structure based on Discontinuous Conduction Mode Single-Ended Primary Inductor Converter (DCM SEPIC) with a single power electronic switch, proposes a converter which is cost-effective and suitable for the small wind turbine used in residential applications. Furthermore, other advantages of the proposed converter include...
A low cost front-end converter with maximum power per ampere for rooftop wind turbines
, Article IEEE Access ; Volume 9 , 2021 , Pages 131236-131244 ; 21693536 (ISSN) ; Rezazadeh, G ; Tahami, F ; Ravanji, M. H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Small Permanent Magnet Synchronous Generators (PMSGs) are widely used in small rooftop wind turbines. In order to inject the electric power generated by the PMSG, into the grid, a back-to-back AC/DC/AC converter is required. In this paper, a low cost with high efficiency converter is proposed for the rectifier stage to obtain the maximum power per ampere of PMSG. This structure based on Discontinuous Conduction Mode Single-Ended Primary Inductor Converter (DCM SEPIC) with a single power electronic switch, proposes a converter which is cost-effective and suitable for the small wind turbine used in residential applications. Furthermore, other advantages of the proposed converter include...
Proposal of a Modular Structure and a Load Sharing Strategy among Back to Back Converters for Wind Turbines
, M.Sc. Thesis Sharif University of Technology ; Mokhtari, Hossein (Supervisor)
Abstract
The utilization of wind power has been increasing in recent years which lead to enhance the the usage of wind power capacity in the range of MegaWatt. However, due to the limitation ofswitching devices capacity, which exists in power electronic converters, improving the capacity of wind power generation is not accessible. Thus, a feasible solution for this problem is paralleling power electronics converters, which increases both the capacity of power generation and the reliability of wind turbine systems. Nevertheless, paralleling converters may cause a circulating-current which brings current discrepancy, current waveform distortion, power losses, increase in THD of currents, and reduction...
Interaction of the dynamics of doubly fed wind generators with power system electromechanical oscillations
, Article IET Renewable Power Generation ; Volume 7, Issue 2 , March , 2013 , Pages 89-97 ; 17521416 (ISSN) ; Ranjbar, A. M ; Sharif University of Technology
2013
Abstract
The interaction of the dynamics of doubly fed wind generators with the electromechanical mode of nearby synchronous generators (SGs) can affect the small signal stability of power systems with high penetration levels of wind power. In this study, a novel approach is developed to investigate these interactions and their impact on the damping of power system oscillations. In this approach it is not necessary to model the dynamic behaviour of system SGs and only the frequencies of system oscillations are important. This approach is based on the sensitivity of SGs electromechanical eigenvalue with respect to variations in the Jacobian matrix of power system. By applying this approach to a test...
The impact of wind farms with doubly fed induction generators on power system electromechanical oscillations
, Article Renewable Energy ; Volume 50 , 2013 , Pages 780-785 ; 09601481 (ISSN) ; Ranjbar, A. M ; Sharif University of Technology
2013
Abstract
Introduction of large amounts of new wind generation can affect the small signal stability of power systems with three mechanisms: displacing synchronous generators (SGs); reducing SGs power generation; and the dynamics of wind farms (WFs) interacting with the electromechanical mode of SGs. In this paper a novel approach is developed to investigate the impact of the latter mechanism on existing power systems oscillations. In this approach, the dynamic behavior of grid connected WFs is studied independent of the dynamic behavior of system SGs. This approach helps to identify the conditions in which the dynamics of WFs may interact with the electromechanical mode of SGs. Also it helps to...
Dynamic behavior and transient stability analysis of fixed speed wind turbines
, Article Renewable Energy ; Volume 34, Issue 12 , 2009 , Pages 2613-2624 ; 09601481 (ISSN) ; Parniani, M ; Sharif University of Technology
Abstract
This paper analytically investigates the dynamic behavior of fixed speed wind turbines (FSWTs) under wind speed fluctuations and system disturbances, and identifies the nature of transient instability and system variables involved in the instability. The nature of transient instability in FSWT is not similar to synchronous generators in which the cause of instability is rotor angle instability. In this paper, the study of dynamic behavior includes modal and sensitivity analysis, dynamic behavior analysis under wind speed fluctuation, eigenvalue tracking, and using it to characterize the instability mode, and investigating possible outcomes of instability. The results of theoretical studies...
Application of state feedback controller to ensure robust d-stable operation of virtual synchronous generators
, Article IEEE Transactions on Energy Conversion ; Volume 36, Issue 2 , 2021 , Pages 602-610 ; 08858969 (ISSN) ; Toulabi, M ; Ranjbar, A. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
This article presents a comprehensive small signal model for a virtual synchronous generator (VSG) integrated into a microgrid. In the developed state-space, active and reactive power control loops of the VSG as well as resistances, and reactances of the lines are considered. Based on this model, the robust D-stable region in terms of different values of inertia constant $(M)$, and damping coefficient $(D)$ values of the VSG is obtained. To enhance both transient performance as well as guarantee the robust D-stable operation of VSG, an optimization problem is also proposed. Moreover, a new control method is suggested to damp frequency oscillations of the microgrid. The proposed controller is...
Stand alone performance of permanent magnet synchronous wind power generator with current source matrix converter
, Article Electric Power Components and Systems ; Volume 43, Issue 8-10 , 2015 , Pages 1018-1027 ; 15325008 (ISSN) ; Mokhtari, H ; Chang, L ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
A matrix converter is a voltage/current source AC/AC frequency converter. In grid-connected operation of a variable-speed permanent magnet synchronous wind power generator, the matrix converter is normally controlled as a voltage source converter. In this control method, the generator-side voltage is synthesized from the grid-side voltage source. However, in the stand-alone mode of operation, the grid-side stiff voltage source is not available, and the input filter of the matrix converter is unstable. In this article, a new control method is presented that controls a permanent magnet synchronous wind generator in a stand-alone mode with a matrix converter as a current source converter. The...
Design of Three-Phase to Single-phase Converter Suitable for Small Range Wind Turbine with PMSG
, M.Sc. Thesis Sharif University of Technology ; Mokhtari, Hossein (Supervisor)
Abstract
In this research a special Three-Phase to Single-Phase converter has been proposed to connect a three-phase Permanent Magnet Synchronous Generator (PMSG) of a wind turbine to a single-phase network. Common back-to-back converter used for this application employs a bulk capacitor in its DC link to generate the pulsating component of the single-phase side instantaneous power. This capacitor is costly and reduces system overall reliability. This problem is alleviated in this work by providing the single-phase load pulsating power using the PMSG large inductances. The proposed system leaves the PMSG torque ripple-free while providing the single-phase load power. With the help of this method,...
Analysis and Improvement of The Low-Voltage Ride Through Capability of Permanent-Magnet Synchronous Generator-Based Wind Turbines
, M.Sc. Thesis Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
Permanent-magnet synchronous generators have attracted more attention in recent years due to their special advantages which make them a suitable option for variable-speed wind turbines.Low-voltage ride through capability is one of the main concerns in widespread use of wind turbines in electric grids. Nowadays wind turbines are expected to remain connected to the grid during voltage dips and support the voltage recovery process by supplying reactive power.This thesis aims at behavior analysis and performance improvement of permanent-magnet synchronous generator-based wind turbines during grid faults. A simple method is presented to overcome the over current problem of the grid-side converter...
Design and Implementation of High Efficient Power Converter for Small PM Synchronous Wind Generator
, M.Sc. Thesis Sharif University of Technology ; Tahami, Farzad (Supervisor)
Abstract
The global wind energy capacity has been increased rapidly in the past few years and became the fastest developing renewable energy technology. Small Permanent Magnet Synchronous Generators (PMSG’s) are widely used in low power wind turbines because they don’t need a gearbox and complicated control systems. In order to inject the electrical power generated by PMSG to the grid, an AC-DC-AC power electronic converter is required. A novel low cost efficient AC-DC converter is proposed to obtain the maximum power per ampere of PMSG. The new structure for the rectifier stage of the AC/AC converter is based on a DCM operated SEPIC converter and can convert the variable voltage and frequency of...