Sensitivity-based supervisory control scheme for multi-microgrid distribution systems

Abstract

With increasing penetration of renewables and storage solutions, multiple microgrids are expected to be interconnected through the distribution infrastructure in the near future. These microgrids are typically controlled in a decentralized manner, and the overall stable operation of the distribution system comes under the purview of the distribution system operator. This paper presents a supervisory control scheme to improve the stability of such a system with droop-controlled inverters and synchronous machines in the event of poorly damped power flows. The droop coefficients of the controllable inverters are manipulated in real-time based on a novel sensitivity criterion so as to obtain the maximum damping effort per unit additional power injected. This prevents the overloading of any one inverter or group of inverters in the system and reduces the power sharing disparity that arises from the supervisory control process. Sensitivity-based supervisory control provides an efficient alternative to computation-intensive analysis of eigenvalues in the event of contingencies, thereby reducing the response time. Simulation results are provided to demonstrate the effectiveness of the proposed supervisory control scheme in restoring damping, as well as its robustness to communication failure.