This talk presents two new control techniques for grid-connected voltage source power electronic converters. The first part of the talk introduces an estimation algorithm to estimate the grid voltage and control a single-phase grid connected converter without dedicated grid voltage sensor. The focus is given to current controlled architectures which need phase locked loops (PLL) for their operation. The estimation method is proposed based on the active and reactive power transfer from the converter to the grid. In addition to the estimation of the grid voltage, the proposed method also generates the unit vectors and frequency information analogous to any conventional PLL structure. The second part of the talk analyzes the opportunities in power-angle synchronization control of a grid-tied bidirectional dc-ac converter for low voltage (utility level) grids. In contrast to current control approaches, power-angle synchronization aims to control the power flow between the converter and grid by controlling the output voltage of the converter. It is shown that the designed compensators ensure stable operation controlling the desired power flow to and from the grid, are immune to grid fluctuations and to a large extent can cater grid unbalanced conditions.
Subhajyoti Mukherjee received the B.E. degree from Jadavpur University, Kolkata, India, in 2007, the M.Tech. degree from Indian Institute of Technology, Kharagpur, India, in 2010 and the Ph.D. degree from Missouri University of Science and Technology, Rolla, USA, in 2017, all in Electrical Engineering. He is currently a Postdoctoral Research Associate in the Power Electronics and Machinery Research group at Oakridge National Laboratory, Knoxville, USA. His research interests include modeling and control of power electronic converters for various applications, wireless power transfer systems, ac microgrids, wide bandgap devices and their application to power electronics, exploring new power converter topologies for interfacing renewable sources of energy, server power supplies, pulse width modulation techniques and motor drives. He has eight years of industrial and research experience in power converter design, analysis and modeling, hardware organization, hardware debugging and digital control in power electronics.