Performance Analysis and Comparative Study of LMI-Based Iterative PID Load-Frequency Controllers of a Single-Area Power System

This paper provides a comparison of the performance and the design steps for four robust static output feedback Proportional-Integral-Derivative (PID) controllers. The first one presents an Iterative PID (IPID) that guarantees the stability of the closed-loop system. In the second and the third controllers, Iterative PID based on H2 (IPIDH2) and H∞ (IPIDHI) performances, respectively, are investigated. The role of H∞ is to minimize the disturbance effect whereas H2 is used to improve the transients of the system output. The last one is an Iterative PID that is characterized by the Maximum (IPIDM) regulated output of the closed loop system with its command input being bounded. The Iterative Linear Matrix Inequality (ILMI) technique is developed to find the feedback gains of the designed PID controllers. The proposed design technique is applied to the Load Frequency Control (LFC) problem of a single-area power system. The effects of ILMI tuning variables on the system dynamic response are given and discussed. To test and compare the effectiveness of the controllers, diverse simulation tests are carried out under diverse disturbances and parameters change with the presence of the Generation Rate Constraint (GRC), inherent system nonlinearity. The results prove that the proposed iterative PID controllers are very useful for LFC power system. Key-Words: Load frequency control, Iterative PID, Linear matrix inequalities, H-infinity norm, H-2 norm, maximum power output control.