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A novel online system‐identification‐based control design for damping inter‐area oscillations in power systems using supplementary wide‐area excitation control is presented. The identification is based on a partly reduced‐order and a partly full‐order model of the grid. Assuming the grid to be divided into coherent areas with phasor measurement units located across the grid, the coherent states of the generators are averaged while the non‐coherent states, such as the internal states of each power system stabilizer, are not. A hybrid state vector consisting of these averaged and non‐averaged states is computed, and used for identifying a hybrid linear time‐invariant state‐space model. A linear quadratic regulator based on this hybrid model is, thereafter, designed. The reduced‐order part of the model is found to save significant amount of online time for both learning and control, while the full‐order part serves to enhance closed‐loop stability. N4SID with randomized singular value decomposition (rSVD) is used for making the identification loop fast. The reduced‐dimensional controller is finally implemented using a broadcast control strategy. The design is extended to non‐linear models of power systems using Carleman bilinearization. Results for linear and bilinear control designs are validated using the IEEE 68‐bus power system model. [ABSTRACT FROM AUTHOR]

In this paper, we present an overview of the applications of graph theory in power system modeling, dynamics, coherency, and control. First, we study synchronization of generator dynamics using both nonlinear and small-signal representations of classical structure-preserving models of power systems in light of their network structure and the weights associated with the nodes and edges of the network graph. We overview important necessary and sufficient conditions for both phase and frequency synchronization. We highlight the role of graph structure in coherency properties, and introduce the idea of generator and bus aggregation whereby dynamic equivalent models of large power grids can be developed while retaining the concept of a “bus” in the network graph of the equivalent model. We also discuss several new results on graph sparsification for designing distributed controllers for power flow oscillation damping. [ABSTRACT FROM AUTHOR]

This paper develops a measurement-based method for estimating a two-machine reduced model to represent the interarea dynamics of a radial, multimachine power system. The method uses synchronized bus voltage phasor measurements at two buses and the line current on the power transfer path. The innovation is the application of the interarea oscillation components in the voltage variables resulting from disturbances for extrapolating system impedances and inertias beyond the measured buses. Expressions for the amplitudes of the bus voltage and bus frequency oscillations as functions of the location on the transmission path are derived from a small-signal perturbation approach. The reduced model provides approximate response to disturbances on the transfer path and offers an alternative to model reduction techniques based on detailed system models and data. [ABSTRACT FROM AUTHOR]

In our recent work [1] , we constructed a reduced-order model of the Western Electricity Coordinating Council (WECC) power system using mathematically derived parameters from real Synchrophasor data. These parameters include inter and intra-area impedances, inertias, and damping factors for aggregate synchronous generators representing five geographical, and yet coherent, areas of WECC. In this paper, we use this reduced-order model as a tool to design a supplementary controller for a Static VAr Compensator (SVC), located at the terminal bus of one of the aggregate generators. Wide-area feedback consisting of phase angle and frequency measurements from Phasor Measurement Units (PMUs) in the other areas is used to design this controller. The objective is to damp the inter-machine oscillation modes of the reduced-order model, which in the full-order system corresponds to inter-area oscillations. The controller input is chosen via statistical variance analysis, and its parameters are tuned to improve the damping factors of the slow modes. The model is implemented in a real-time digital simulator, and validated using a wide range of disturbance scenarios. The closed-loop system is observed to be highly robust to all of these disturbances as well as the choice of operating points. Detailed experimental analyses of the capacity of the SVC to satisfy the damping specifications of supplementary control are also presented via multiple contingencies. The results are promising in aiding damping of inter-area modes in WECC, especially at a time of increasing penetration of wind and other renewable resources. [ABSTRACT FROM AUTHOR]