PNNL

Abstract

Electromechanical oscillations affect weakly or sparsely connected power systems. If not properly addressed these oscillations can pose a threat to the stability of the system. This paper proposes a novel methodology to use loads, the demand-side of the system, to effectively damp these swings also known as inter-area oscillations. In the proposed methodology loads are assigned to a cluster and the power consumption of the entire load cluster is modulated for oscillation damping. The load cluster control action is obtained from an optimal output feedback control (OOFC) strategy. The paper presents a modification to the regular OOFC formulation that puts a constraint on the sum of the rows in the optimal gain matrix. This constraint is convenient when the feedback signals are generator speeds. The sum of the rows of the optimal gain matrix in such a case is the droop gain of each load actuator. The paper uses time-domain simulations of a large-scale power system to demonstrate the performance of different proposed controllers. The simulation results illustrate the impact of the row constraint on the steady state behavior of the power system after a large generator drop. The simulations results show that the proposed controllers successfully damp the inter-area oscillations in the system.