Mahmut Temel Özdemir

The effects on stability region of the fractional-order PI controller for one-area time-delayed load–frequency control systems

One of the controllers used in load–frequency control systems is the PI controller, taking account of time delay originating from measurement and communication. In control systems, along with the use of the fractional-order controller, computing parameter space exhibited stable behaviour on the controller parameters and analysing its efficiency have become a significant issue. This study focuses on computing the effects of the fractional integral order (α) on the stable parameter space for the control of a one-area delayed load–frequency control system in the case of a fractional-order PI controller. The effect of time delay on the stable parameter space is also investigated at different fractional integral orders (α) in the time-delayed system with fractional-order PI controller. For this purpose, a characteristic equation of the delayed system with the fractional-order PI controller is obtained, and the stable parameter spaces of the controller are computed according to the fractional integral order (α) and time delay (τ) values using the stability boundary locus method, which is graphics based. Moreover, the generalized modified Mikhailov criterion is used for testing the stability region on the Kp − Ki plane. The obtained results verified that the stability region on the Kp − Ki plane change depending on the α and τ.

LOAD-FREQUENCY OPTIMIZATION WITH HEURISTIC TECHNIQUES IN A AUTONOMOUS HYBRID AC MICROGRID

The main problem that arises during the operation of all these power systems is load-frequency control. Load-frequency control is a common problem of power systems that are connected to an interconnected system. Variations in the frequency in the interconnected power systems can lead to large-scale and serious instability problems. And in microgrids, load-frequency control is of great importance in order to provide active power balancing, especially when the microgrids are connected to the main grid. In this study, AC microgrid structures and their basic control cycles are examined. A sample autonomous hybrid AC microgrid structure was modeled in the MATLAB environment and an autonomous hybrid AC microgrid system isolated from the main grid was considered to be the case study. In this case, the controller gains are determined according to the Optic Inspired Optimization, Bacterial Swarm Optimization, Artificial Bee Colony Optimization, Ant Colony Optimization, Grey Wolf Colony Optimization algorithms, costing with the ISE performance criteria which are commonly recognized in the literature. The controller gains determined by optimization were simulated for time domain responses in the generated model and the results were analyzed.

Development of a Renewable Energy Based DC Excitation System in a Micro Hydro Power Plant

MHPPs (micro hydro power plants) have become prominent in hydropower plants as a solution to provide the energy demands of the grid. In this study, a new hybrid renewable energy based DC excitation system for synchronous generator in the developed MHPP system is introduced. Proposed hybrid DC excitation system consists of solar & h ydrogen energy based power generating systems. Hybrid renewable energy based system is used for the excitation of the synchronous generator in the MHPP test system. The renewables are used as a secondary energy source to provide the excitation current to a synchronous generator that generates energy in MHPP. A PV (photovoltaic) array is used as the main source of excitation, and a FC (fuel cell) stack is used for DC excitation in the lack of sunshine. In the experimental setup, an electrical control card is developed, and a microcontroller is used to perform the proposed excitation system. All experimental results obtained from 5 kW rated power MHHP test system. Experimental results show that, the proposed method provides the continuous excitation current, and the operation of the synchronous generator is uninterrupted. The proposed method is also practical and easily implemented for MHPP systems.