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23rd iranian Conference on Electrical Engineering, ICEE 2015

作者： Moradnouri, Ahmad Vakilian, Mehdi Elhaminia, Pedram Bahrami, Mansour Electrical Engineering Department Center of Excellence in Power System Management and Control Sharif University of Technology Tehran Iran

ISBN: (纸本)9781479919727

in this paper the radial and axial forces developed under windings short circuit conditions in two different designs of a 630 kYA distribution transformer (using analytic a^id finite element method) are determined and compared. The simulation results using FEM software verify the results of the employed analytic method. These results show that although the transformer with larger dimensions have a better operating performance and lower total owning cost with respect to one with smaller sizes (assuming the same mechanical strength for winding and support structures of both), the risk of failure due to its related short circuit forces elevates in the former. Additionally, this paper presents some analytical expressions which demonstrate the relationships between short circuit forces and transformer geometrical parameters. These relationships help transformer designers to choose the best dimensional parameters to improve the transformer performance in such a way that risk of failure of transformer due to short circuit forces doesn't increase 01 increase in a lower paste if compared with the other sample. © 2015 IEEE.

关键词： Finite element method

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Fast detection of open-switch fault in cascaded H-Bridge multilevel converter

Fast detection of open-switch fault in cascaded H-Bridge mul...

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power Electronic and Drive systems and Technologies Conference (PEDSTC)

作者： Mahmoud Shahbazi MohammadReza Zolghadri Center of Excellence in Power System Management & Control (CEPSMC) Sharif University of Technology Tehran Iran

ISBN: (纸本)9781479976546

Cascaded H-Bridge converter has recently been utilized in different high-power applications due to its modular and simple structure. In order to have a balanced operation after a fault occurrence in this converter, it is necessary to detect the switch fault and its location. In this paper, a fast power switch fault detection method is presented to identify the fault and its location. Only one voltage measurement per phase is required by this method, and the fault detection is faster compared to the existing methods. Moreover, it is easy for implementation on an FPGA device, due to the use of simple math, relational and state machine blocks. The proposed method is verified by computer simulations.

关键词： Switches Field programmable gate arrays Computers Computational modeling Ice

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Impact of erroneous measurements on power system real-time security analysis

Impact of erroneous measurements on power system real-time s...

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iranian Conference on Electrical Engineering (ICEE)

作者： Mohammad Farajollahi Mahmud Fotuhi-Firuzabad Amir Safdarian Electrical Engineering Department Sharif University of Technology Center of Excellence in Power System Control and Management Tehran Iran

power system security analyses as well as decisions made to preserve system security are all on the basis of an approximate insight over the system status. This approximate insight is provided based on erroneous measurements throughout the system. The error in the input data may result in a misleading index which either increases system operating costs or jeopardizes service continuity. This paper aims at establishing an step-by-step algorithm to study impacts of error in measurements on system security indices. Two different security indices representing under voltage severity and over load severity are studied in this paper. The proposed algorithm has three major steps. In the first step, typical measurements are sampled according to the system operating state and randomly generated errors. This is done using Monte Carlo sampling approach. The second step is to extract an approximate model of the system true state which is done via state estimators. Then, security indices are calculated for both the approximated and true states in the third step. Comparison between the indices demonstrates impacts of the erroneous measurements on security assessment.

关键词： Decision support systems Electrical engineering Conferences

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Changing Electrical Safety

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IEEE INDUSTRY APPLICATIONS MAGAZINE 2014年第5期20卷 6-6页

作者： Capelli-Schellpfeffer, Mary Center of Excellence in Power System Management & Control Sharif University of Technology Tehran Iran

n this year’s “Electrical Safety” columns, we have been exploring the topic of changing electrical safety, with thoughtleaders offering their perspectives. Our guest contributors have had truly prestigious careers dedicated to advancing the well-being of those who work in and benefit from the power economy. Reflects on the remarks and observations made.

关键词： Electrical safety power systems reliability power system safety

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A new power management control strategy for a MV microgrid with both synchronous generator and inverter-interfaced distributed energy resources

A new power management control strategy for a MV microgrid w...

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IEEE International Symposium on Industrial Electronics (ISIE)

作者： Mohsen Zangeneh Mohsen Hamzeh Hossein Mokhtari Houshang Karimi The Center of Excellence in Power System Management & Control Sharif University of Technology Tehran Iran

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 responses of the MV microgrid is significantly improved by using the proposed power management scheme. The performance of the proposed control strategy is verified by using digital time-domain simulation study in the PSCAD/EMTDC software environment.

关键词： Microgrids Voltage control Synchronous generators Reactive power Steady-state Frequency control control systems

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Design and implementation of a single phase grid-connected PV inverter with a new active damping strategy

Design and implementation of a single phase grid-connected P...

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power Electronic and Drive systems and Technologies Conference (PEDSTC)

作者： M. Hamzeh Y. Karimi E. Asadi H. Oraee The Center of Excellence in Power System Management & Control Sharif University of Technology Tehran Iran

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 proposed control scheme is verified by using digital time-domain simulation in MATLAB Simulink environment. Moreover, the proposed scheme has been tested experimentally in the laboratory.

关键词： MATLAB Voltage control Frequency control Resonant frequency Arrays Inverters Time-frequency analysis

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An adaptive droop control method for low voltage DC microgrids

An adaptive droop control method for low voltage DC microgri...

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power Electronic and Drive systems and Technologies Conference (PEDSTC)

作者： A. Khorsandi M. Ashourloo H. Mokhtari The Center of Excellence in Power System Management & Control Sharif University of Technology Tehran Iran

DC microgrids (MGs) are becoming popular as effective means to integrate different energy resources. Conventionally, the droop control is adopted as a decentralized control method for power sharing in DC MGs. However, current sharing accuracy or voltage regulation deteriorates due to the effects of line impedances. In this paper, a new adaptive control strategy is proposed for DC MGs. In low load conditions, the output currents of the DGs are far from their maximum acceptable limits. Therefore, current sharing accuracy is not important. As load increases, the output currents of the DGs approach their maximum acceptable limits. Therefore, at high load conditions, accurate current sharing is necessary. In the proposed method, with increasing the load, the equivalent droop gains are automatically increased to attain more accurate current sharing. Simulation results are provided to verify the validity and effectiveness of the proposed method.

关键词： Microgrids Distributed power generation Reliability Accuracy

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A heuristic ranking approach on capacity benefit margin determination using pareto-based evolutionary programming technique

Scientific World Journal

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Scientific World Journal 2015年第1期2015卷 731013页

作者： Othman, Muhammad Murtadha Abd Rahman, Nurulazmi Musirin, Ismail Fotuhi-Firuzabad, Mahmud Rajabi-Ghahnavieh, Abbas Committee of Research (CORE) Advanced Computing and Communication (ACC) Universiti Teknologi MARA Shah Alam Selangor 40450 Malaysia Faculty of Electrical Engineering Universiti Teknologi MARA Shah Alam Selangor 40450 Malaysia Engineering Centre University Malaysia Perlis Kampus Kubang Gajah Arau Perlis 02600 Malaysia Centre of Excellence in Power System Management and Control Electrical Engineering Department Sharif University of Technology Tehran 11365-11155 Iran Department of Energy Engineering Sharif University of Technology Tehrana 11365-11155 Iran

This paper introduces a novel multiobjective approach for capacity benefit margin (CBM) assessment taking into account tie-line reliability of interconnected systems. CBM is the imperative information utilized as a reference by the load-serving entities (LSE) to estimate a certain margin of transfer capability so that a reliable access to generation through interconnected system could be attained. A new Pareto-based evolutionary programming (EP) technique is used to perform a simultaneous determination of CBM for all areas of the interconnected system. The selection of CBM at the Pareto optimal front is proposed to be performed by referring to a heuristic ranking index that takes into account system loss of load expectation (LOLE) in various conditions. Eventually, the power transfer based available transfer capability (ATC) is determined by considering the firm and nonfirm transfers of CBM. A comprehensive set of numerical studies are conducted on the modified IEEE-RTS79 and the performance of the proposed method is numerically investigated in detail. The main advantage of the proposed technique is in terms of flexibility offered to an independent system operator in selecting an appropriate solution of CBM simultaneously for all areas. © 2015 Muhammad Murtadha Othman et al.

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A practical application of the Delphi method in maintenance-targeted resource allocation of distribution utilities

A practical application of the Delphi method in maintenance-...

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International Conference on Probabilistic Methods Applied to power systems (PMAPS)

作者： Payman Dehghanian Moein Moeini-Aghtaie Mahmud Fotuhi-Firuzabad Roy Billinton Sharif University of Technology Tehran Tehran IR Center of Excellence in Electrical Power System Management and Control Sharif University of Technology Tehran Iran Department of Electrical Engineering University of Saskatchewan Saskatoon Saskatchewan Canada

Trying to find the most efficient and cost-effective decisions on the maintenance of different component types in power distribution systems is an increasingly challenging concern largely driven by the current financial constraints in distribution utilities worldwide. In regard to deal with this challenge, the paper presents a practical application of the Delphi method and the Modified Analytical Hierarchical Process (MAHP) that can be used to find the most critical component types of the system in order to assist in accordingly allocating the available maintenance budget. The proposed approach involves the experience and knowledge held by experts and the historical empirical performance data in the utility data management systems to create the associated decisions. The approach has been applied in the Alborz Distribution system in Tehran, iran. The results obtained and the lessons learned are reported in detail.

关键词： Maintenance engineering Decision making Resource management power distribution power cables Reliability Planning

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A decentralized self-adjusting control strategy for reactive power management in an islanded multi-bus MV microgrid

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Canadian Journal of Electrical and Computer Engineering 2013年第1期36卷 18-25页

作者： Hamzeh, Mohsen Mokhtari, Hossein Karimi, Houshang Center of Excellence in Power System Management and Control Sharif University of Technology Tehran 11365-9363 Iran Department of Electrical Engineering École Polytechnique de Montréal QC H3C 3A7 Canada

This paper presents a decentralized self-adjusting reactive power controller for the autonomous operation of a multi-bus medium voltage (MV) microgrid. The main objective of the proposed control strategy of each distributed generation (DG) unit is to compensate the reactive power of its local loads and to share the reactive power of the nonlocal loads among itself and other DG units. The proposed control strategy includes an improved droop controller whose parameters are adjusted according to the reactive power of the local loads. A virtual inductive impedance loop is augmented to the voltage controller to enhance the steady state and transient responses of the proposed reactive power management scheme. The small signal analysis of the proposed method is presented to ensure stability of the system for different reactive power values. The presented strategy considerably enhances the voltage profiles of the microgrid buses as compared with the conventional droop methods. The proposed method does not require any communication link and minimizes the reactive power flow in the MV lines, thus reducing the losses of the overall microgrid. The performance of the proposed control scheme is verified by using digital time-domain simulation studies in the PSCAD/EMTDC software environment. © 2013 IEEE.

关键词： controllers

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