Abstract
This paper proposes a robust proportional-integral (PI) controller with its parameters designed by constrained population extremal optimization for load frequency control problem of multi-area interconnected. During the process of optimization, the robust performance index is used as fitness function, where linear matrix inequalities technique is employed to describe the H∞ constraint, and the taking error performance requirement such as integral time absolute error is incorporated as another constraint. Three different two-area interconnected power systems are used as test systems to demonstrate the effectiveness of the proposed controller by comparing with other PI control methods and one optimized model predictive control. In addition, in order to investigate the performance of proposed controller for the LFC problem of large scale system, a three-area interconnected power system is used as another test system. The comprehensive experimental results fully demonstrate that the proposed control scheme in this paper performs better than other control strategies on the most considered scenarios under the conditions of load disturbance and parameters uncertainties in terms of system response and control performance indices.
1. Introduction
Load frequency control (LFC) is of great importance for power systems or microgrids to maintain the scheduled system frequency and power exchange between areas during normal and abnormal conditions [1]. The control objective of LFC is to minimize the frequency deviation and net tie-line flow error between control areas. More specifically, the LFC should be ensured stabilization considering system nonlinearities, model parameters uncertainties, and load disturbance or resonance attack [1–4], which may take place in realistic power engineering. Over the past decades, considerable efforts have been devoted to developing control strategies for LFC problem, which can be roughly separated into two categories. The first category employs various advanced techniques [4–14] to design advanced controllers for LFC of interconnected power system or microgrids. For example, model predictive control [6–9], H∞ and μ-synthesis [10], fuzzy logic [12,13] and sliding model technique [14] have been utilized for LFC issue.
5. Conclusion
In this paper, we have proposed a robust PI controller with its parameters optimized by CPEO embedded by TCH method to handle the constraint called CPEO-LMI-PI control scheme, wherein the LMI technique is applied to describe the H∞ constraints and ITAE taking error performance requirement constraint is employed as another constraint for improving the control performance and dealing with some nonlinear terms. To validate the strong competitiveness, we use four Experiments by comparing with different controllers.
