Distributed Frequency Control with Operational Constraints, Part II: Network Power Balance
For power system operators, this work provides a distributed frequency control method that maintains operational constraints, addressing a practical need for scalable and robust control in interconnected grids.
This paper proposes a distributed controller for optimal frequency control in multi-area power systems where power mismatch is balanced over the whole network, ensuring tie-line powers and regulation capacity constraints are satisfied at equilibrium and during transients. The controller is proven asymptotically stable using an invariance principle, with simulations demonstrating effectiveness.
In Part I of this paper we propose a decentralized optimal frequency control of multi-area power system with operational constraints, where the tie-line powers remain unchanged in the steady state and the power mismatch is balanced within individual control areas. In Part II of the paper, we propose a distributed controller for optimal frequency control in the network power balance case, where the power mismatch is balanced over the whole system. With the proposed controller, the tie-line powers remain within the acceptable range at equilibrium, while the regulation capacity constraints are satisfied both at equilibrium and during transient. It is revealed that the closed-loop system with the proposed controller carries out primal-dual updates with saturation for solving an associated optimization problem. To cope with discontinuous dynamics of the closed-loop system, we deploy the invariance principle for nonpathological Lyapunov function to prove its asymptotic stability. Simulation results are provided to show the effectiveness of our controller.