Distributed Frequency Control with Operational Constraints, Part I: Per-Node Power Balance

TL;DR

This paper proposes a decentralized control strategy for multi-area power systems that ensures frequency regulation, operational constraints satisfaction, and tie-line power restoration without communication, proven to be stable and optimal.

Contribution

It introduces a fully decentralized frequency control method for per-node power balance that adapts to unknown disturbances and satisfies operational constraints.

Findings

Control strategy is fully decentralized and communication-free.

System converges to the optimal frequency regulation solution.

Simulation confirms effectiveness and stability of the proposed control.

Abstract

This paper addresses the distributed optimal frequency control of multi-area power system with operational constraints, including the regulation capacity of individual control area and the power limits on tie-lines. Both generators and controllable loads are utilized to recover nominal frequencies while minimizing regulation cost. We study two control modes:the per-node balance mode and the network balance mode. In Part I of the paper, we only consider the per-node balance case, where we derive a completely decentralized strategy without the need for communication between control areas. It can adapt to unknown load disturbance. The tie-line powers are restored after load disturbance, while the regulation capacity constraints are satisfied both at equilibrium and during transient. We show that the closed-loop systems with the proposed control strategies carry out primal-dual updates for solving the associated centralized frequency optimization problems. We further prove the closed-loop systems are asymptotically stable and converge to the unique optimal solution of the centralized frequency optimization problems and their duals. Finally, we present simulation results to demonstrate the effectiveness of our design. In Part II of the paper, we address the network power balance case, where transmission congestions are managed continuously.