**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**32451

##### A Robust Approach to the Load Frequency Control Problem with Speed Regulation Uncertainty

**Authors:**
S. Z. Sayed Hassen

**Abstract:**

The load frequency control problem of power systems has attracted a lot of attention from engineers and researchers over the years. Increasing and quickly changing load demand, coupled with the inclusion of more generators with high variability (solar and wind power generators) on the network are making power systems more difficult to regulate. Frequency changes are unavoidable but regulatory authorities require that these changes remain within a certain bound. Engineers are required to perform the tricky task of adjusting the control system to maintain the frequency within tolerated bounds. It is well known that to minimize frequency variations, a large proportional feedback gain (speed regulation constant) is desirable. However, this improvement in performance using proportional feedback comes about at the expense of a reduced stability margin and also allows some steady-state error. A conventional PI controller is then included as a secondary control loop to drive the steadystate error to zero. In this paper, we propose a robust controller to replace the conventional PI controller which guarantees performance and stability of the power system over the range of variation of the speed regulation constant. Simulation results are shown to validate the superiority of the proposed approach on a simple single-area power system model.

**Keywords:**
Robust control,
power system,
integral action,
minimax LQG control.

**Digital Object Identifier (DOI):**
doi.org/10.5281/zenodo.1331741

**References:**

[1] O. I. Elgerd, "Control of electric power systems," IEEE Control Syst. Mag., vol. 1, no. 2, pp. 4-16, 1981.

[2] H. Bevrani, Robust Power System Frequency Control. Springer, 2009.

[3] R. K. Boel, M. R. James, and I. R. Petersen, "Robustness and risk sensitive filtering," IEEE Trans. Autom. Control, vol. 47, no. 3, pp. 451- 461, 2002.

[4] P. Dupuis, M. R. James, and I. R. Petersen, "Robust properties of risksensitive control," Mathematics of Control, Signals, and Systems, vol. 13, no. 4, pp. 318-332, 2000.

[5] I. R. Petersen, M. R. James, and P. Dupuis, "Minimax optimal control of stochastic uncertain systems with relative entropy constraints," IEEE Trans. Autom. Control, vol. 45, no. 3, pp. 398-412, 2000.

[6] I. R. Petersen, V. A. Ugrinovskii, and A. V. Savkin, Robust Control Design using H∞ methods. Springer-Verlag, London, 2000.

[7] A. V. Savkin and I. R. Petersen, "Minimax optimal control of uncertain systems with structured uncertainty," Int. J. Robust and Nonlinear Control, vol. 5, no. 2, pp. 119-137, 1995.

[8] V. A. Ugrinovskii and I. R. Petersen, "Time-averaged robust control of stochastic partially observed uncertain systems," in Proc. IEEE Conf. on Decision and Control, Tampa, Florida, 1998, pp. 784-789.

[9] ÔÇöÔÇö, "Finite horizon minimax optimal control of stochastic partially observed time varying uncertain systems," Mathematics of Control, Signals and Systems, vol. 12, no. 1, pp. 1-23, 1999.