Grid Strength Constrained Cooperative Control of Renewable Power Plants for Guaranteed Small-Signal Stability

Recently, sub-synchronous oscillations have been frequently witnessed in large-scale renewable power plants under weak grid conditions. Because such oscillations may occur unpredictably, it is necessary to mitigate them in real time from the control timeframe. To this end, this letter develops a cooperative control approach based on the grid strength metric of generalized short-circuit ratio (gSCR). Specifically, an optimal control problem which maximizes renewable power output while maintaining a desirable small-signal stability margin characterized by gSCR is formulated. Then, consensus + innovations based cooperative control is designed to achieve the objective in real time. Simulation results validate the effectiveness of the proposed approach.