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current-controller
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Predictive current control for programmable electronic ac load
, Article 11th Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2020, 4 February 2020 through 6 February 2020 ; 2020 ; Zolghadri, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
Nowadays, Programmable Electronic AC Load (PEAL) is widely used to test various devices such as solar inverters, UPSs, filters, generators, and generally test all AC power and measuring devices. In this paper, Model Predictive Current Control (MPCC) is used for control of a programmable AC load. In each period, switching state that minimizes the cost function is selected and applied to the converter. Cost function is the square of the current components error. The effect of the horizon of prediction on the quality of the load current is investigated. To decrease the calculations burden, a limited search pool is used. Simulation results confirm that using two steps prediction horizon with...
Enhanced control of grid forming VSCs in a micro-grid system under unbalanced conditions
, Article 9th Annual International Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2018, 13 February 2018 through 15 February 2018 ; Volume 2018-January , April , 2018 , Pages 380-385 ; 9781538646977 (ISBN) ; Mokhtari, H ; Ghasemi, M. A ; SHarif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Due to the technical advances in power electronic industry, employing inverter-based distributed energy resources (IBDERs) are increased in electric power systems. Distributed generators (DGs) with the rating capacity of few megawatts are commonly connected to the distribution level of power systems which are inherently unbalanced. A cluster of IBDERs and loads form a small-scale grid called microgrid (MG) which can operate independent of the main grid. In a MG, grid forming voltage source converters (VSCs) are used to control the voltages and frequency of the MG. However, grid forming VSCs with conventional control schemes cannot do this task properly when the MG is unbalanced. In this...
Design of a bridgeless PFC with line-modulated fixed off-time current control and zero-voltage switching
, Article PECon2010 - 2010 IEEE International Conference on Power and Energy, 29 November 2010 through 1 December 2010 ; 2010 , Pages 129-134 ; 9781424489466 (ISBN) ; Zolghadri, M. R ; Nasirian, V ; Noroozi, N ; Sharif University of Technology
Abstract
In this paper, the Line-Modulated Fixed Off-Time method is used as the current control strategy for a Power Factor Corrector (PFC) pre-regulator. A zero voltage switching PWM (ZVS-PWM) auxiliary circuit is configured to perform ZVS in the switches. Soft commutation of the main switch is achieved without additional current stress. A significant reduction in the total conduction loss is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path .The proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode...
DC-link loop bandwidth selection strategy for grid-connected inverters considering power quality requirements
, Article International Journal of Electrical Power and Energy Systems ; Volume 119 , 2020 ; Mokhtari, H ; Ghasemi, M. A ; Peyghami, S ; Davari, P ; Blaabjerg, F ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
DC-link voltage and output current control loops are two cascaded loops in the control structure of grid-connected inverters. A high DC-link voltage loop bandwidth (DCL-BW) provides more disturbance rejection capability for the control loop and is preferred from control system perspective. However, for stability issues, this BW is limited and must be sufficiently less than that of the current control loop. Among the different control schemes, instantaneous active reactive control (IARC) method provides the highest possible DCL-BW (i.e., 0.02 × switching frequency). Having this degree of freedom in the controller design, a proper methodology should be defined for selection of DCL-BW. In this...
Neutron Noise Calculation using Nodal Expansion Method
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor) ; Hosseini, Abolfazl (Co-Advisor)
Abstract
The present M.Sc. thesis consists of two sections including the static calculation and neutron noise calculation in rectangular and hexagonal geometries. The multi-group, two dimensional neutron diffusion equations and corresponding adjoint equations are solved in the static calculation. The spatial discretization of equations is based on Average Current Nodal Expansion Method (ACNEM). Size of nodes is the same size of the fuel assemblies in modeling both of rectangular and hexagonal geometries. The results are benchmarked against the valid results for BIBLIS-2D and IAEA-2D benchmark problems. In the second section, neutron noise calculations are performed for two types of noise sources,...
Design and implementation of a single phase grid-connected PV inverter with a new active damping strategy
, Article PEDSTC 2014 - 5th Annual International Power Electronics, Drive Systems and Technologies Conference ; Feb , 2014 , pp. 72-77 ; Karimi, Y ; Asadi, E ; Oraee, H ; Sharif University of Technology
Abstract
This paper presents an effective current injection method for a single phase grid-connected PV inverter with LCL filter. The main objective of the proposed control strategy is to compensate the resonance effect of the LCL filter. In the proposed control strategy, a resonance compensator is augmented to the conventional proportional resonance (PR) controller to attenuate current oscillations in resonance frequency of LCL filter. The proposed strategy robustly regulates the output current of grid connected inverter in various grid impedances and provides a high quality current injection capability for the PV inverter in harmonic polluted condition of the grid voltage. The performance of the...
A fast and cost-effective control of a three-phase stand-alone inverter
, Article 8th Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2017, 14 February 2017 through 16 February 2017 ; 2017 , Pages 67-72 ; 9781509057665 (ISBN) ; Keikha, O ; Yaghoubi, M ; Tahami, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
This paper proposes a straightforward control method for voltage control of a three-phase transformer-based inverter in uninterruptible power supplies or distributed generation systems. The approach offers a dual-loop design consisting inner current control loop and outer voltage loop. Sliding mode current controller provides desired bandwidth for voltage controller which consists of a state feedback term for stabilization and resonant term for harmonic damping. The proposed scheme provides fast dynamic response and low total harmonic distortion even for high power inverters with the limitations of switching frequency and LC filter components. Experimental studies for 2KVA linear and...
Modification in Topology and Control Method for Improving Performance of Modular Multilevel Converter in 2N+1 and N+1 Modulation
, M.Sc. Thesis Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
In Modular Multilevel converter, it is necessary to attain different objectives simultaneously. One of the most effective control methods which can cope with this kind of systems is the Model Predictive Control (MPC). This method predicts the values of control objectives based on different feasible states and determines the optimal one using cost functions. The number of feasible states can increase when the number of switches increases in the converter. This makes the MPC unable to be applied in the MMCs with hundereds of submodules (SMs) in each arm because of its heavy computational burden. In this thesis, a modified model predictive control is proposed to reduce the computational burden....
Control of gas metal arc welding by an extended DMC
, Article Proceedings of the IEEE International Conference on Control Applications ; 2012 , Pages 1430-1434 ; 9781467345033 (ISBN) ; Haeri, M ; Sharif University of Technology
Abstract
Efficient control of gas metal arc welding process enables us to have high quality products in consequence of achieving high quality weld. In this paper, an extended dynamic matrix controller is designed and applied on the gas metal arc welding process, which is considered as a nonlinear multi-inputs multi-outputs system. In order to reach a high quality weld, the outputs, welding current and arc length, are effectively controlled by open circuit voltage and wire feed speed. The structure and performance of the proposed controller are discussed in detail, and then a set of simulation results is presented to verify its efficiencies
Robust control of an autonomous four-wire electronically-coupled distributed generation unit
, Article IEEE Transactions on Power Delivery ; Volume 26, Issue 1 , September , 2011 , Pages 455-466 ; 08858977 (ISSN) ; Yazdani, A ; Iravani, R ; Sharif University of Technology
2011
Abstract
This paper proposes a control strategy for the autonomous (islanded) operation of a four-wire, electronically-coupled distributed generation (DG) unit which can feed a highly unbalanced load, e.g., due to the presence of single-phase loads. In the grid-connected mode, the power-electronic interface of the DG unit enables the exchange of real and reactive power with the distribution network, based on the conventional dq-frame current control strategy. The current control scheme is disabled subsequent to the detection of an islanding event, and the proposed controller is activated. The proposed control strategy utilizes: i) an internal oscillator to maintain the island frequency and ii) a...
Distributed secondary control in DC microgrids with low-bandwidth communication link
, Article 7th Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2016, 16 February 2016 through 18 February 2016 ; 2016 , Pages 641-645 ; 9781509003754 (ISBN) ; Blaabjerg, F ; Peyghami Akhuleh, S ; Mokhtari, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
In this paper, a distributed secondary power sharing approach with low bandwidth communication network is proposed for low voltage direct current (LVDC) microgrids. Conventional droop control causes voltage drop in the grid and also a mismatch on the current of converters in the case of consideration of the line resistances. Proposed control system carry out the current value of the other converters to reach the accurate current sharing and suitable voltage regulation as well. Voltage and current controllers locally regulate the voltage and current of converters as a secondary controller. Secondary controller is realized locally and the communication network is only used to transfer the data...
Control of parallel three- phase inverters using optimal control and SVPWM technique
, Article IEEE International Symposium on Industrial Electronics, 5 July 2009 through 8 July 2009 ; 2009 , Pages 1823-1828 ; 9781424443499 (ISBN) ; Mokhtari, H ; Sharif University of Technology
Abstract
In this paper, optimal control strategy is applied to parallel three-phase inverters using SVPWM technique. The three-phase system is transformed to a synchronous-stationary frame, suitable cost functions are defined, and the switching schemes are determined for the inverters. The control strategy minimizes the circulating current between the inverters, therefore, proper load sharing scheme is achieved. Simulations are performed for steady state and load change operation, and the results which show the suitability of the controller are provided. ©2009 IEEE
Design and analysis of three-phase variable hysteresis controlled single stage sepic based rectifier
, Article 2009 International Conference on Electric Power and Energy Conversion Systems, EPECS 2009 ; 2009 ; 9789948427155 (ISBN) ; Mohammadpour, A ; Nejadpak, A ; Zolghadri, M. R ; Sharif University of Technology
Abstract
A methodology for controlling three phase PFC Sepic converter is presented, and behavior of the system is evaluated. The converter is connected in delta at the input and parallel at the output side, and is controlled by variable hysteresis current control method. By this approach, the current drawn by each of the individual converters is controlled to be in phase with its own input voltage. Detailed design criteria for the power and control stages of the single-phase SEPIC converter are presented and effects of this method on THD are verified
A new noise-immune method to detect protective CT saturation and its release instants
, Article 2016 IEEE International Conference on Power and Renewable Energy, ICPRE 2016, 21 October 2016 through 23 October 2016 ; 2017 , Pages 284-287 ; 9781509030682 (ISBN) ; Vakilian, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
CT saturation is a phenomenon that can cause inaccurate fault current measurement and may result in related protective relay failure to block the high current flow under a fault condition in a power system. Hence, it is required to develop a method to detect occurrence of CT saturation with a good accuracy under presence of noise in a power system. In this paper, a new method having the afore-mentioned characteristics is presented. The main benefit of exploiting the introduced approach here for detecting CT saturation is its high level of reliability as well as its reasonable operational speed in CT saturation detection. In other words, these two properties are implemented to this method....
Controller parameters optimization for multi-terminal DC power system using ant colony optimization
, Article IEEE Access ; Volume 9 , 2021 , Pages 59910-59919 ; 21693536 (ISSN) ; Kashif, S. A. R ; Nasir, A ; Rasool, A ; Liaquat, S ; Padmanaban, S ; Mihet Popa, L ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Voltage source converter based multi - terminal DC grids (VSC - MTDC) are widely used for integration of renewable resources. Control of these grids requires vector control method, which includes inner and outer current controllers, tuning of these controllers is very important. Conventionally used tuning methods consider approximated linear model to tune the proportional - integral (PI) parameters of voltage source converter (VSC) which fails to produce optimum disturbance rejection results. In this research an Ant Colony Optimization (ACO) technique is used to get the optimum parameters of inner and outer power control layers for multi - terminal DC system. ACO is applied simultaneously on...
Controller parameters optimization for Multi-Terminal Dc power system using ant colony optimization
, Article IEEE Access ; Volume 9 , 2021 , Pages 59910-59919 ; 21693536 (ISSN) ; Kashif, S. A. R ; Nasir, A ; Rasool, A ; Liaquat, S ; Padmanaban, S ; Mihet-Popa, L ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Voltage source converter based multi - terminal DC grids (VSC - MTDC) are widely used for integration of renewable resources. Control of these grids requires vector control method, which includes inner and outer current controllers, tuning of these controllers is very important. Conventionally used tuning methods consider approximated linear model to tune the proportional - integral (PI) parameters of voltage source converter (VSC) which fails to produce optimum disturbance rejection results. In this research an Ant Colony Optimization (ACO) technique is used to get the optimum parameters of inner and outer power control layers for multi - terminal DC system. ACO is applied simultaneously on...
A comparative study on current control methods for load balancing and power factor correction using STATCOM
, Article 2005 IEEE Russia Power Tech, PowerTech, St. Petersburg, 27 June 2005 through 30 June 2005 ; 2005 ; 9781424418749 (ISBN) ; Parniani, M ; Sadriyeh, S. M. R ; Sharif University of Technology
2005
Abstract
This paper investigates several current control methods for load balancing and power factor correction based on distribution Static Compensator (STATCOM). Two different configurations are considered for STATCOM; a three leg inverter, and three single phase inverters. It is assumed that the STATCOM is associated with a load that is remote from the supply. After a brief introduction, control structure based on PWM method and simulation results using PSCAD are presented. Next, the same system is simulated using hystersis control method. Both methods employ the instantaneous symmetrical components theory for load balancing and power factor correction. At the end, a comparison between two methods...
Top-down design of a low-power multi-channel 2.5-Gbit/s/channel gated oscillator clock-recovery circuit
, Article Design, Automation and Test in Europe, DATE '05, Munich, 7 March 2005 through 11 March 2005 ; Volume I , 2005 , Pages 258-263 ; 15301591 (ISSN); 0769522882 (ISBN); 9780769522883 (ISBN) ; Tajalli, A ; Atarodi, M ; Leblebici, Y ; Sharif University of Technology
2005
Abstract
We present a complete top-down design of a low-power multi-channel clock recovery circuit based on gated current-controlled oscillators. The flow includes several tools and methods used to specify block constraints, to design and verify the topology down to the transistor level, as well as to achieve a power consumption as low as 5mW/Gbit/s. Statistical simulation is used to estimate the achievable bit error rate in presence of phase and frequency errors and to prove the feasibility of the concept. VHDL modeling provides extensive verification of the topology. Thermal noise modeling based on well-known concepts delivers design parameters for the device sizing and biasing. We present two...
Decentralized control of parallel connection of two distributed generation units
, Article 35th Annual Conference of the IEEE Industrial Electronics Society, IECON 2009, Porto, 3 November 2009 through 5 November 2009 ; 2009 , Pages 358-362 ; Karimi, H ; Iravani, R ; Sharif University of Technology
Abstract
This paper presents a decentralized control strategy for the autonomous (islanded) operation of parallel connection of two distributed generation (DG) units. The DG units are electronically interfaced to the host grid at the same point of common coupling (PCC), where the local load is also supplied. In the grid-connected mode, the voltage-sourced converter (VSC) of each DG unit controls the exchange of real and reactive power components with the host grid, based on the conventional dq-current control strategy. In the islanded mode, one of the DG units provides voltage and frequency control for the island, and the other DG unit continues to operate with the pre-islanding dq-current control...
Analysis and Control of Circulating Current in High-Power Full Converter Wind Turbines with Modular Structure
, M.Sc. Thesis Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
This thesis aims at developing control system of a full converter wind turbine with modular and parallel back-to-back converters. Modular structures and paralleling of power electronic converters are the state-of-the-art methods for increasing their transferable power to the grid. Technological advances in high power wind turbines, especially for the offshore installations, which contain permanent magnet synchronous generators with back-to-back full converters, promote the use of modular structures.
In addition to developing the regular control systems of wind turbines for modular structures, selection of appropriate structures, power sharing between parallel converters and mitigation of...
In addition to developing the regular control systems of wind turbines for modular structures, selection of appropriate structures, power sharing between parallel converters and mitigation of...