Dr. Mohammad Amin is an Associate Professor at the Department of Electric Power Engineering at NTNU. He received the B.Sc. degree in electrical and electronic engineering from Chittagong University of Engineering and Technology, Chittagong, Bangladesh, the M.Sc. degree in electric power engineering from Chalmers University of Technology, Gothenburg, Sweden, and the Ph.D. in Engineering Cybernetics from Norwegian University of Science and Technology (NTNU), Trondheim, Norway in 2008, 2011 and 2017, respectively. The title of his PhD thesis is Small-signal Stability Characterization of Interaction Phenomena between HVDC System and Wind Farms.
Previously, he was a Senior Research Associate in the Dept. of Electrical and Computer Engineering at Illinois Institute of Technology, Chicago from 2017 to 2019. He was with the Department of Electrical and Electronic Engineering (EEE) in International Islamic University Chittagong (IIUC), Bangladesh from 2008 to 2013. Dr Amin has research experiences from five countries: USA, Norway, China, Sweden and Bangladesh.
Dr Amin's research activities mainly focus on power electronics application to power system, distributed generation, renewable energy integration, HVDC transmission, FACTS, microgrid, smart grids, hybrid or fully electric vehicles, robust control theory for power electronics system, process control, and embedded systems. His vision is to develop a top research center that fully explores the beauty of seamless integration of control and power electronics and addresses fundamental problems in various electric power systems, with strong support from funding bodies and industrial companies.
Dr. Amin's following journal paper received the 2018 IEEE JESTPE First Prize Paper Award from IEEE Power Electronics Society.
M. Amin and M. Molinas, "Understanding the Origin of Oscillatory Phenomena Observed Between Wind Farms and HVDC Systems", IEEE Journal Journal of Emerging and Selected Topics in Power Electronics, vol. 5, no. 1, pp. 378-392, March 2017
Dr. Amin's following conference paper won IEEE SYPA Award at IECON 2018 from IEEE Industrial Electronics Society.
M. Amin, Q-C Zhong, L. Zhang, Z. Li and M. Shahidehpour, “Small-Signal Modeling and Analysis of VSM for Distributed Generation in a Weak Grid”, the 44th Annual Conference of the IEEE Industrial Electronics Society, 2018, (IECON 2018), Washington D.C., USA.
M. Amin and Q.-C. Zhong, "Resynchronization of Distributed Generation based on the Universal Droop Controller for Seamless Transfer Between Operation Modes", in IEEE Transaction on Industrial Electronics, To be published, 2019.
M. Amin, C. Zhang, A. Rygg, E. Unamuno, M. Molinas, and M. Belkhayat, "Nyquist Stability Criterion and its Application to Power Electronic Systems", in Wiley Encyclopedia of Electrical and Electronics Engineering, To be published, 2019.
M. Amin and M. Molinas, "A Gray-box Method for Stability and Controller Parameter Estimation in HVDC-connected Wind Farms based on Non-parametric Impedance", in IEEE Transaction on Industrial Electronics, Volume: 66, Issue: 3, March 2019.
M. Amin and M. Molinas, "Small-Signal Stability Assessment of Power Electronics based Power Systems: A Discussion of Impedance- and Eigenvalue-based Methods", in IEEE Transaction on Industry Application, vol. 53, no. 5, pp. 5014 - 5030, June 2017.
M. Amin, A. Rygg and M. Molinas, "Self-synchronisation of wind farm in MMC-based HVDC system: A Stability Investigation", in IEEE Transaction on Energy Conversion, vol. 32, no. 2, pp. 458-470, June 2017.
M. Amin and M. Molinas, "Understanding the Origin of Oscillatory Phenomena Observed Between Wind Farms and HVDC Systems", IEEE Journal of Emerging and Selected Topics in Power Electronics , vol. 5, no. 1, pp. 378-392, March 2017.
M. Amin, M. Molinas, J. Lyu and X. Cai, "Impact of Power Flow Direction on the Stability of VSC-HVDC seen from the Impedances Nyquist Plot", IEEE Transaction on Power Electronics, vol. 32, no. 10, pp. 8204-8217, Oct. 2017.
Seamless Transfer of Microgrid Operation Modes
Distributed generation (DG) inverters can operate in the islanded mode and the grid-connected mode. When these DG inverters operate in the islanded mode, they often form a microgrid. The magnitude and phase of the main grid voltage deviate from the microgrid voltage. If the microgrid is connected to the main grid under such condition, it results in a high transient overcurrent which is harmful to the system. This paper presents a new, simple and effective resynchronization mechanism for the universal droop control (UDC) DG inverters to achieve a seamless transfer from the islanded mode to the grid-connected mode. Simulation and experimental results are provided to verify the effectiveness of the proposed method. The result shows that the high transient overcurrent can be avoided and a seamless connection/reconnection to the main grid can be achieved.
Stability of a Black/Gray-box system
"A Gray-box Method for Stability and Controller Parameter Estimation in HVDC-connected Wind Farms based on Non-parametric Impedance", IEEE Transaction on Industrial Electronics, Volume: 66, Issue: 3, March 2019.
Estimation of critical control parameters is a desirable tool feature for stability analysis and impedance shaping of high voltage dc (HVdc) connected wind farms. Accurate estimation of such parameters would be enabled by access to detailed models, which is not always the case in real wind farms. Industrial secrecy is one of the main factors hindering the access to such models. This paper proposes a gray-box method that, with basic assumptions about the control structure of the wind energy conversion system (WECS), can estimate the parameters of its controllers. The method is based on the measurements of frequency domain equivalent impedance combined with nonparametric impedance identification used in the solution of an inverse problem. The method makes possible to specify which part of the equivalent WECS impedance has a major impact on the stability of the system and according to this, reshape the impedance to enforce stability. Once the critical controller bandwidth is identified with this method, an instability mitigation technique is proposed based on reshaping the impedance by retuning the critical controllers of the interconnected converters. In order to avoid interaction between the HVdc rectifier and the WECS inverter, the controllers of both converters need to be retuned in such a way that the q-axis impedance magnitude of the HVdc system is kept lower than the q-axis impedance magnitude of the wind farm at the frequency of the phase-locked loop bandwidth. The results show that the method ensures the stability of the system by retuning only the critical controller parameters.
Electrical Oscillation in Offshore Wind Farm
Field experience has shown that subsynchronous oscillation and harmonic resonance can occur between wind farms (WFs) and high voltage dc (HVdc) systems. The oscillations can appear in the presence of background harmonics due to the interaction between the wind energy conversion system's (WECS's) converter controller, HVdc converter controller, and the impact of the interconnection system impedance. However, the root causes of these oscillations observed in the field are not entirely understood and they can be attributed to various sources within the components and controllers of the interconnected system. This paper explores the possible causes of these oscillations by investigating the impact of controllers and components in the WF and in the voltage-source converter (VSC)-based HVdc transmission system. In order to understand this phenomenon, the impedance of both the WF and the HVdc from the offshore ac collection point is analytically derived to identify potential resonance points. The impedance frequency responses of the WF and the HVdc converter indicate the potential resonance at low frequency. The origin of these oscillations can be attributed to the propagation of the WECS resonance through the WECS full converter dc link and the interaction between the WECS and the HVdc system. Once the source and the load impedance are identified, an impedance-based stability method is adopted in order to determine the stability. In an attempt to improve the oscillatory phenomena, an active damping scheme is implemented on the offshore HVdc rectifier. An analysis and time-domain simulation results with its respective harmonic spectra show that the implemented active damping is very effective in eliminating the oscillations observed in the interconnected system. Moreover, this paper presents the role of the ratio between the bandwidths of the interconnected areas, as having an essential role in the root cause of the instability. The general rule is observed that when the bandwidth of the HVdc rectifier (which is the source) is faster than the bandwidth of the load (WFs inverter); the system operates stably.