Evaluation of Generator Damping Using Oscillation Energy Dissipation and the Connection With Modal Analysis

Energy-based damping evaluation for exciter control in power systems

“…Loads are assumed to be unchanged during transients. Generators are governed by a forth-order transient model [16] as follows with notation listed in Table I,…”

“…The time-dependent term D i ω 0 ν 2 i dt represents the energy dissipation by the damping factor of the generator in Bus i. The energy dissipation part in energy flows is termed as net energy flow [15], [16] that indicates damping performance of a generator. However, the D i ω 0 ν 2 i dt is not the only element dissipating energy.…”

“…W 1 (8a) represents the transient energy stored in the field windings; W 2 (8b) is the energy dissipation part due to the effect of field windings' resistances, which is concluded in [16]; W 3 (8c) is the one due to the interactions between q-axis transient voltage E q and internal field voltage E fd , which will illustrate the impact of exciter control on damping performance. Therefore, W 3 is further analyzed so that the impact of exciter control on energy dissipation can be revealed.…”

“…Without loss of generality, the mechanical power P m is assumed to be constant (no turbine governor) as in [15], [16]. Therefore, the energy flow from a generator (7) with field windings, exciter control and PSS taken into account is…”

“…Instead, we propose to directly study the net energy flow of generators based on the dynamic models of generators and exciters. Furthermore, not only the energy dissipation contribution of generator field windings can be evaluated [16], but the damping contribution of exciter control to the system can be revealed by our innovative proposed method as well, based on the analysis of the interactions between exciter control and dynamic behavior of generator field windings in terms of energy dissipation. The proposed approach facilitates deeper understanding of the source of oscillations and the diagnosis of exciter control.…”