Control Inversion: A Clustering-Based Method for Distributed Wide-Area Control of Power Systems

Wide-area control (WAC) has been shown to be an effective tool for damping low-frequency oscillations in power systems. In the current state of art, WAC is challenged by two main factors, namely, scalability of design and complexity of implementation. In this paper, we present a control design called control inversion that bypasses both of these challenges using the idea of clustering. The basic philosophy behind this method is to project the original power system model into a lower-dimensional state space through clustering and aggregation of generator states, and then designing a linear-quadratic regulator (LQR) controller for the lower-dimensional model. This controller is finally projected back to the original coordinates for wide-area implementation. The main problem is, therefore, posed as finding the projection which best matches the closed-loop performance of the WAC controller with that of a reference LQR controller for damping low-frequency oscillations. We verify the effectiveness of the proposed design using the IEEE 48-machine power system model of the Northeastern Power Coordinating Council.