Block-Decentralized Damping Control of Power Systems using Retrofit Control Theory

This paper develops a new block-decentralized wide-area control design for improving damping performance of power systems based on retrofit control. Retrofit control is a modular control approach for a stable network system whose subsystems are managed by their corresponding subsystem operators. For power systems, these subsystems refer to individual utility areas, and their operators refer to the utility owners. We first show that the state deflections of the grid model caused by a fault cannot be expressed in the form of a local disturbance, thereby making it a bottleneck for satisfactory control performance. To overcome this difficulty, we propose a method for choosing an appropriate subsystem of interest based on the notion of a design structure matrix (DSM). The DSM illustrates the dependency among the different areas of the power system, and helps the utility owners and system operators to choose an appropriate area. The effectiveness of the proposed method is examined through a numerical simulation with the IEEE 68-bus power system.