Small Signal Analysis of Rotating Reference Frame Based Synchronization Control for Microgrid to Grid Changeover

Deepak Gehlot; Shoubhik  Mukherjee; A.S. Krishna Priya; Mukesh Kumar Pathak

doi:10.18618/REP.e202601

Authors

Deepak Gehlot Indian Institute of Technology Roorkee https://orcid.org/0009-0001-4630-3344
Shoubhik Mukherjee BHEL Corp.R&D https://orcid.org/0009-0001-2571-7521
A.S. Krishna Priya BHEL Corp.R&D https://orcid.org/0009-0005-5513-8167
Mukesh Kumar Pathak Indian Institute of Technology Roorkee

DOI:

https://doi.org/10.18618/REP.e202601

Keywords:

Current controller, Droop control, Grid following converter, Grid forming converter, Hardware in Loop controller, Phase Locked Loop

Abstract

Reliable synchronization is essential for ensuring stability during the transition of microgrids between islanded and grid-connected operation, particularly in converter-dominated lowinertia systems. This paper outlines a small signal analysis for the novel synchronization control of an islanded microgrid comprising two or more parallel-connected voltage source converters. It focuses on the development of simple and effective microgrid synchronization strategies with a minimum Rate of Change of Frequency (ROCOF), enabling the integration of Distributed Energy Resources (DER) into growing low-inertia power systems. The proposed method is based on a rotating reference frame-based algorithm with two Proportional-Integrator (PI) controllers at the secondary control level, minimizing the computational complexity by reducing the number of control loops compared with conventional approaches. A small-signal model has been developed and validated using eigenvalue analysis to ensure stability during the mode transitions. The developed controls were validated on a test setup comprising of a 25 kW Grid-Forming Converter (GFC) and a 25 kW Grid-Following Converter (GFL).

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Author Biographies

Deepak Gehlot , Indian Institute of Technology Roorkee

Deepak Gehlot is an electrical engineering graduate with two decades of experience in BHEL across power plant operations and power electronics technologies. His work focuses on grid-connected converters, traction propulsion systems, energy storage applications etc. His professional interests include converter design, control algorithms, and high-power system applications.. Deepak is currently pursuing Ph.D. (External) at IIT Roorkee.

Shoubhik Mukherjee, BHEL Corp.R&D

Shoubik Mukherjee is an ECE graduate with 17 years of experience at BHEL in embedded control, FPGA development, and power electronics engineering. He has worked on advanced converter controls, real-time digital platforms, and high-performance power electronic systems. His areas of expertise include FPGA architectures, embedded software, and digital control algorithms. Shoubik is currently a Ph.D. scholar (External) at IIT Hyderabad.

A.S. Krishna Priya, BHEL Corp.R&D

holds a Bachelor’s degree in Electrical and Electronics Engineering and a Master’s degree in Electrical Engineering. She has 17 years of experience at BHEL Corporate R&D specializing in power electronics converter design and control. Her work includes grid-connected inverters, traction electrics, active power filters, and advanced control software development.

Mukesh Kumar Pathak, Indian Institute of Technology Roorkee

received his B.E. from L.D. Engineering College, Ahmedabad, in 1986, and his M.Tech. and Ph.D. from IIT Delhi in 1995 and 2006. He previously served at NIT Hamirpur and NIT Kurukshetra before joining the Electrical Engineering Department at IIT Roorkee in 2007, where he is now a Professor. His research focuses on solar PV and EV converters, electric drive control, three-phase and multiphase motor drives, smart grids, microgrids, and solid-state transformers.

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