Multi-Level Power-Imbalance Allocation Control for Secondary Frequency Control in Power Systems

This paper focuses on secondary frequency controlof large-scale power systems. First a centralized and a consen-sus control based distributed control law are presented, thena multi-level control law, named Multi-Level Power-ImbalanceAllocation Control (MLPIAC), for the large-scale power systemspartitioned into more than one region. The centralized anddistributed control law are applied within each region and overthe regions respectively. Besides restoring nominal frequency witha minimized control cost, MLPIAC also considers the transientbehavior of the system after a disturbance. We present a controlstrategy different from the one applied in the Power-ImbalanceAllocation Control (PIAC), which also enhances the transientbehavior of the frequency through an accelerated convergenceof the control inputs eliminating overshoots in MLPIAC. In thelevel of the distributed control over the regions, the consensus ofthe marginal costs can be accelerated through a single parameter.Furthermore, because the number of regions is smaller than thatof nodes, MLPIAC is more effective to obtain the minimizedcost than the purely distributed control law. The asymptoticstability of MLPIAC is proven using the Lyapunov method andthe performance is evaluated through simulations.