Showing 6 results for Alizadeh
M. H. Refan, H. Valizadeh,
Volume 8, Issue 3 (September 2012)
Abstract
Accurate and reliable time is necessary for financial and legal transactions, transportation, distribution systems, and many other applications. Time synchronization protocols such as NTP (the Network Time Protocol) have kept clocks of such applications synchronized to each other for many years. Nowadays there are many commercial GPS based NTP time server products at the market but they almost have a high price. In this paper we are going to use a low cost GPS engine to build a time server to provide time synchronization with accuracy of a few milliseconds. This time server is relatively very cheap and it can be used in almost all typical applications. We also proposed a software based NTP time server implemented in MATLAB as well.
M. Alizadeh Moghadam, R. Noroozian, S. Jalilzadeh,
Volume 11, Issue 3 (September 2015)
Abstract
This paper presents modeling, simulation and control of matrix converter (MC) for variable speed wind turbine (VSWT) system including permanent magnet synchronous generator (PMSG). At a given wind velocity, the power available from a wind turbine is a function of its shaft speed. In order to track maximum power, the MC adjusts the PMSG shaft speed.The proposed control system allowing independent control maximum power point tracking (MPPT) of generator side and regulate reactive power of grid side for the operation of the VSWT system. The MPPT is implemented by a new control system. This control system is based on control of zero d-axis current (ZDC). The ZDC control can be realized by transfer the three-phase stator current in the stationary reference frame into d-and q-axis components in the synchronous reference frame. Also this paper is presented, a novel control strategy to regulate the reactive power supplied by a variable speed wind energy conversion system. This control strategy is based on voltage oriented control (VOC). The simulation results based on Simulink/Matlab software show that the controllers can extract maximum power and regulate reactive power under varying wind velocities.
E. Alizadeh, A. M. Birjandi, M. Hamzeh,
Volume 12, Issue 4 (December 2016)
Abstract
This paper proposes an autonomous and economic droop control scheme for DC microgrid application. In this method, a cost-effective power sharing technique among various types of DG units is properly adopted. The droop settings are determined based on an algorithm to individually manage the power management without any complicated optimization methods commonly applied in the centralized control method. In the proposed scheme, the system retains all the advantages of the traditional droop method while minimizes the generation costs of the DC microgrid. In the proposed method, all DGs are classified in a sorting rule based on their total generation cost and the reference voltage of their droop equations is then determined. The proposed scheme is applied to a typical DC microgrid consisting of four different types of DGs and a controllable load. The simulation results are presented to verify the effectiveness of the proposed method using MATLAB/SIMULINK software.
E. Alizadeh, A. Motie Birjandi, M. Hamzeh,
Volume 13, Issue 4 (December 2017)
Abstract
This paper proposes a decentralized control technique to minimize the total operation cost of a DC microgrid in both grid-connected and islanded modes. In this study, a cost-based droop control scheme based on the hourly bids of all participant distributed generators (DGs) and the hourly energy price of the utility is presented. An economic power sharing technique among various types of DG units is adopted to appropriately minimize the daily total operation cost of DC microgrid without a microgrid central controller. The DC microgrid may include non-dispatchable DG units (such as photovoltaic systems) and dispatchable generation units. Unlike other energy management techniques, the proposed method suffers neither from forecasting errors for both load demand and renewable energy power prediction modules, nor from complicated optimization techniques. In the proposed method, all DGs and the utility are classified in a sorting rule based on their hourly bids and open market price, and then the droop parameters are determined. The simulation results are presented to verify the effectiveness of the proposed method using MATLAB/SIMULINK software. The results show that the proposed strategy is able to be implemented in various operation conditions of DC microgrid with resistance to uncertainties.
M. Sanatgar, M. R. Alizadeh Pahlavani, A. Bali Lashak,
Volume 15, Issue 3 (September 2019)
Abstract
This paper presents the control approach for single inverter dual coupled brushless DC motors (DCBLDC) drive system. One of the basic requirements of such systems, is the power balance between two motors and on the other hand, minimizing mechanical fluctuations in order to avoid mechanical equipment damage especially in the state of mechanical resonance. This paper also presents an improved form of the conventional direct torque control (IDTC) for the DCBLDC, which can be used on nine-switch inverters (NSIs). The conventional approaches used in the coupled motors are considered, and then a combination of torque and velocity control is proposed for DCBLDC. After theoretical analysis and drive modeling, whose performance has been simulated by MATLAB/Simulink in terms of dispatching balanced power as well as dealing with transient phenomena owing to malfunctioning of the mechanical connection line. Finally, experiments with the 120W BLDC motors are executed to verify the feasibility of the proposed approach.
Hassan Alizadeh Shyrayeh, Iraj Ahmadi, Mohammad Mirzaie, Masoud Ahmadi Gorji,
Volume 18, Issue 4 (December 2022)
Abstract
The progressive application of non-linear loads in distribution systems (DS) increases current harmonics flow in DS's apparatuses, especially distribution transformers (DTs). Since DTs' operating temperature rises due to the harmonics flow, their loading should be reduced such that the hot spot temperature (HST) is preserved under its permissible value. This means that DTs' available capacity is influenced by load harmonic content. In this paper, a novel formulation for DTs' failure rate in the presence of harmonics is presented as a function of load harmonic contents. Using the suggested equivalent failure rate, DTs' available capacity in harmonic polluted DS is mathematically formulated. Additionally, the presence of the harmonic increases the HST, leading to DTs' aging acceleration. Therefore, the impact of harmonic components on DTs' aging is arithmetically modeled. To evaluate the efficacy of the suggested reliability model, it is applied to three distinct DTs having respectively industrial, commercial, and residential loads. The obtained results indicate that the available capacity of DTs with the same rated capacity would be different regarding to their load harmonic contents. On the other hand, it is comprehended from the achieved results that the aging acceleration factor (Faa) of the DTs increases owing to their load harmonic contents.
