Stability analysis of the time-delayed load frequency control system with renewable energy sources

Nowadays, the renewable energy sources (RES) such as PV solar energy, wind energy, fuel cells are increasing the interest (have a great interest) since the increase in energy consumption due to growing population, limited fossil in the World's resources and serious environmental pollution. In order to use the energy generated by RES, it should be integrated into the Load Frequency Control (LFC) systems. The time delays occur in the LFC systems during data transmission and reception in communications network. This time delays affect negatively the dynamics of the system and even cause the system to become unstable. In this thesis, the effects of the time delays on stability in the load frequency controlled hybrid power generation/storage system are investigated with considering the gain and phase margins. In the first step, the time delay is added to system for the stability analysis. Maximum stability delay margin that system could tolerate before becoming unstable of the system is theoretically calculated by the method of elimination of exponential terms which is available in the literature. Also, the proportional - integral (PI) controller gain effects on the maximum time delay are investigated. Then, stability regions are found theoretically depending on the PI controller gains for any given value of time delay. In the second phase of the study, the theoretical results have been verified by using Matlab / Simulink program. According to the obtained results, the importance of the time delay is shown for the stability of system.