Research Focus: How can we overcome the instabilities of microgrids caused by constant power loads?

Eklas Hossain, Oregon Tech, 3201 Campus Dr, United States

A new Research Paper in Renewable Energy Focus looks to overcome instabilities caused by Constant Power Load with a robust control mechanism - using a Lyapunov Redesign controller.

Title of Peer Reviewed and Accepted Research Paper


  • Eklas Hossain, Oregon Tech, US;
  • Ron Perez, University of Wisconsin-Milwaukee, Center for Sustainable Electrical Energy Systems;
  • Adel Nasiri, University of Wisconsin-Milwaukee, Center for Sustainable Electrical Energy Systems;
  • Ramazan Bayindir, Gazi University.

What are the key findings of your research (in brief)?

Microgrids are a proven solution to provide stable power, even to the most remote communities, and can help communities integrate renewables into their power supply. Our work aims to enable a more stable microgrid system by better handling Constant Power  Loads (CPL).

Using Lyapunov functions, we developed a Lyapunov Redesign Controller to mitigate CPL effects in the microgrids. This controller can run on different algorithms and our research demonstrates the following:

  • The Lyapunov Redesign controller for a microgrid with constant power load helps assure control objectives, retaining the output voltage constant at a predefined point;
  • The Lyapunov Redesign Controller is robust against parametric uncertainties, frequency variations and Additive White Gaussian Noise (AWGN) (we also compared the performance of the Proportional-Integral-Derivative (PID) and Lyapunov Redesign Control technique to microgrid output voltage in the case of nonlinearity, parameter uncertainties, and noise rejection).

Why do your findings matter?

We believe that countering the CPL loads efficiently is a much sought after objective in the microgrid community, the problem having appeared with the incremental use of power electronics starting around 15 years ago. Our findings matter as they outline an efficient way to overcome the instabilities caused by CPL, using a robust control mechanism.

What are the next steps that need to be taken to push this research forward even more?

The next steps required for further development are a thorough investigation of storage systems to determine their optimum capacity and placement, as well as identifying the difficulties of implementing this proposed technique with solutions to address those difficulties; and the optimum placement of the whole system – be it at the generation side, the load side, or in the intermediate circuitry.

Implementing the proposed system in a real microgrid environment could be a suitable option to take this work forward.

Accessing the full text version of the paper
Development of Lyapunov Redesign Controller for Microgrids with Constant Power Loads (Click here for full text access to the Paper, subscription or pay per view available) 

About the Corresponding Author
Dr. Eklas Hossain received his PhD in Renewable Energy and Advanced Control System from the University of Wisconsin-Milwaukee in 2016. He joined Oregon Institute of Technology in 2015 as an Assistant Professor in the Department of Electrical Engineering & Renewable Energy and has been working there ever since. His research interests include energy systems, advanced control systems, renewable energy, microgrid and smart grid.

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