Coordinated Design of Damping Controllers Based on Control Loops Selection and Model Prediction Control in Time Delay Power System

This paper presents a coordinated design for multiple damping controllers in power system considering wide-area feedback signal delay in the wide area measurement system (WAMS). Firstly, a reduced-order model of the power system is identified by subspace state space system identification (N4SID) method and critical modes are determined by modal analysis. Secondly, to select the most suitable control loops, interactions among control loops and controllability/observability of each control loop are considered by using a branch and bound (BAB) method. Finally, a local PSS is designed for the local mode. And a wide-area damping controller based on model prediction control (MPC) is proposed for the inter-area mode. Advantages are as follows. Model identification can directly identify the system model and avoid depending on parameters of power system elements. Moreover, multiple controllers can be designed independently because the process of selecting control loops can obtain control loops with small interactions. In addition, the designed inter-area MPC controller works well in not only different signal delays but also changed system operating conditions. Test results in a two-area four-machine system verify the effectiveness of the proposed design process for multiple damping controllers.