2009 IEEE/PES Power Systems Conference and Exposition, 2009
... Sharma Kolluri (e-mail: vkollur@entergy.com), Sujit Mandal (e-mail: smandal@entergy.com) and ... more ... Sharma Kolluri (e-mail: vkollur@entergy.com), Sujit Mandal (e-mail: smandal@entergy.com) and Floyd Galvan (email: fgalvan@entergy.com) are ... Exhaustive full time-domain transient stability simulations (N-1, N-2 and even Nk contingencies) are then conducted to identify the ...
Power and Energy Society General Meeting, 2015 IEEE, 2015
Dynamic var sources can effectively mitigate fault-induced delayed voltage recovery (FIDVR) issue... more Dynamic var sources can effectively mitigate fault-induced delayed voltage recovery (FIDVR) issues or even voltage collapse. This paper proposes a new approach to optimization of the sizes of dynamic var sources at candidate locations by a Voronoi diagram based algorithm. It first disperses sample points of potential solutions in a searching space, evaluates a cost function at each point by barycentric interpolation for the subspaces around the point, and then constructs a Voronoi diagram about cost function values over the entire space. Accordingly, the final optimal solution can be obtained. Case studies on the WSCC 9-bus system and NPCC 140-bus system have validated that the new approach can quickly identify the boundary of feasible solutions in searching space and converge to the global optimal solution.
IEEE Power and Energy Society General Meeting, Jul 2014
Dynamic reactive power (var) sources, e.g. SVCs and STATCOMs, can effectively mitigate fault-indu... more Dynamic reactive power (var) sources, e.g. SVCs and STATCOMs, can effectively mitigate fault-induced delayed voltage recovery (FIDVR) issues or even voltage collapse. However, their optimal allocation in a power grid is a complicated nonlinear optimization problem since the post-fault voltage trajectories have to be solved to check constraints on voltage responses. Thus, solvers of both nonlinear optimization and power system differential and algebraic equations (DAEs) are required. This paper proposes a new approach to optimize the sizes of dynamic var sources at candidate locations by efficiently interfacing a heuristic linear programming based searching algorithm with power system simulation software. Case studies on a 9-bus system and the IEEE 39-bus system have benchmarked the new approach with an existing representative approach and demonstrated that the new approach can quickly converge to an optimal solution.
Power and Energy Society General Meeting, 2015 IEEE, 2015
This paper develops a test bed based on the Northeastern Power Coordinating Council (NPCC) 48-mac... more This paper develops a test bed based on the Northeastern Power Coordinating Council (NPCC) 48-machine, 140-bus power system model for simulating cascading failures. Then, the paper uses the test bed to demonstrate the interaction model recently proposed by [1] for analyzing cascading failures, identifying key linkages between component failures, and predict propagation of failures. For the NPCC test bed, a new efficient method is proposed to determine line flow limits as critical parameters in cascading failures simulation. Then, those limits are utilized in AC-OPA to generate a database of cascades. Finally, the interaction model is derived based on the database to extract key knowledge on cascades, which can be used for online analysis and simulation of cascading failures.
In this paper the empirical observability gramian calculated around the operating region of a pow... more In this paper the empirical observability gramian calculated around the operating region of a power system is used to quantify the degree of observability of the system states under specific phasor measurement unit (PMU) placement. An optimal PMU placement method for power system dynamic state estimation is further formulated as an optimization problem which maximizes the determinant of the empirical observability gramian and is efficiently solved by the NOMAD solver, which implements the Mesh Adaptive Direct Search (MADS) algorithm. The implementation, validation, and also the robustness to load fluctuations and contingencies of the proposed method are carefully discussed. The proposed method is tested on WSCC 3-machine 9-bus system and NPCC 48-machine 140-bus system by performing dynamic state estimation with square-root unscented Kalman filter. The simulation results show that the determined optimal PMU placements by the proposed method can guarantee good observability of the system states, which further leads to smaller estimation errors and larger number of convergent states for dynamic state estimation compared with random PMU placements. Under optimal PMU placements an obvious observability transition can be observed. The proposed method is also validated to be very robust to both load fluctuations and contingencies.
In this paper the interactions between component failures are quantified and the interaction matr... more In this paper the interactions between component failures are quantified and the interaction matrix and interaction network are obtained. The quantified interactions can capture the general propagation patterns of the cascades from utilities or simulation, thus helping to better understand how cascading failures propagate and to identify key links and key components that are crucial for cascading failure propagation. By utilizing these interactions a high-level probabilistic model called interaction model is proposed to study the influence of interactions on cascading failure risk and to support online decision-making. It is much more time efficient to first quantify the interactions between component failures with fewer original cascades from a more detailed cascading failure model and then perform the interaction model simulation than it is to directly simulate a large number of cascades with a more detailed model. Interaction-based mitigation measures are suggested to mitigate cascading failure risk by weakening key links, which can be achieved in real systems by wide area protection such as blocking of some specific protective relays. The proposed interaction quantifying method and interaction model are validated with line outage data generated by the AC OPA cascading simulations on the IEEE 118-bus system.
2009 IEEE/PES Power Systems Conference and Exposition, 2009
... Sharma Kolluri (e-mail: vkollur@entergy.com), Sujit Mandal (e-mail: smandal@entergy.com) and ... more ... Sharma Kolluri (e-mail: vkollur@entergy.com), Sujit Mandal (e-mail: smandal@entergy.com) and Floyd Galvan (email: fgalvan@entergy.com) are ... Exhaustive full time-domain transient stability simulations (N-1, N-2 and even Nk contingencies) are then conducted to identify the ...
Power and Energy Society General Meeting, 2015 IEEE, 2015
Dynamic var sources can effectively mitigate fault-induced delayed voltage recovery (FIDVR) issue... more Dynamic var sources can effectively mitigate fault-induced delayed voltage recovery (FIDVR) issues or even voltage collapse. This paper proposes a new approach to optimization of the sizes of dynamic var sources at candidate locations by a Voronoi diagram based algorithm. It first disperses sample points of potential solutions in a searching space, evaluates a cost function at each point by barycentric interpolation for the subspaces around the point, and then constructs a Voronoi diagram about cost function values over the entire space. Accordingly, the final optimal solution can be obtained. Case studies on the WSCC 9-bus system and NPCC 140-bus system have validated that the new approach can quickly identify the boundary of feasible solutions in searching space and converge to the global optimal solution.
IEEE Power and Energy Society General Meeting, Jul 2014
Dynamic reactive power (var) sources, e.g. SVCs and STATCOMs, can effectively mitigate fault-indu... more Dynamic reactive power (var) sources, e.g. SVCs and STATCOMs, can effectively mitigate fault-induced delayed voltage recovery (FIDVR) issues or even voltage collapse. However, their optimal allocation in a power grid is a complicated nonlinear optimization problem since the post-fault voltage trajectories have to be solved to check constraints on voltage responses. Thus, solvers of both nonlinear optimization and power system differential and algebraic equations (DAEs) are required. This paper proposes a new approach to optimize the sizes of dynamic var sources at candidate locations by efficiently interfacing a heuristic linear programming based searching algorithm with power system simulation software. Case studies on a 9-bus system and the IEEE 39-bus system have benchmarked the new approach with an existing representative approach and demonstrated that the new approach can quickly converge to an optimal solution.
Power and Energy Society General Meeting, 2015 IEEE, 2015
This paper develops a test bed based on the Northeastern Power Coordinating Council (NPCC) 48-mac... more This paper develops a test bed based on the Northeastern Power Coordinating Council (NPCC) 48-machine, 140-bus power system model for simulating cascading failures. Then, the paper uses the test bed to demonstrate the interaction model recently proposed by [1] for analyzing cascading failures, identifying key linkages between component failures, and predict propagation of failures. For the NPCC test bed, a new efficient method is proposed to determine line flow limits as critical parameters in cascading failures simulation. Then, those limits are utilized in AC-OPA to generate a database of cascades. Finally, the interaction model is derived based on the database to extract key knowledge on cascades, which can be used for online analysis and simulation of cascading failures.
In this paper the empirical observability gramian calculated around the operating region of a pow... more In this paper the empirical observability gramian calculated around the operating region of a power system is used to quantify the degree of observability of the system states under specific phasor measurement unit (PMU) placement. An optimal PMU placement method for power system dynamic state estimation is further formulated as an optimization problem which maximizes the determinant of the empirical observability gramian and is efficiently solved by the NOMAD solver, which implements the Mesh Adaptive Direct Search (MADS) algorithm. The implementation, validation, and also the robustness to load fluctuations and contingencies of the proposed method are carefully discussed. The proposed method is tested on WSCC 3-machine 9-bus system and NPCC 48-machine 140-bus system by performing dynamic state estimation with square-root unscented Kalman filter. The simulation results show that the determined optimal PMU placements by the proposed method can guarantee good observability of the system states, which further leads to smaller estimation errors and larger number of convergent states for dynamic state estimation compared with random PMU placements. Under optimal PMU placements an obvious observability transition can be observed. The proposed method is also validated to be very robust to both load fluctuations and contingencies.
In this paper the interactions between component failures are quantified and the interaction matr... more In this paper the interactions between component failures are quantified and the interaction matrix and interaction network are obtained. The quantified interactions can capture the general propagation patterns of the cascades from utilities or simulation, thus helping to better understand how cascading failures propagate and to identify key links and key components that are crucial for cascading failure propagation. By utilizing these interactions a high-level probabilistic model called interaction model is proposed to study the influence of interactions on cascading failure risk and to support online decision-making. It is much more time efficient to first quantify the interactions between component failures with fewer original cascades from a more detailed cascading failure model and then perform the interaction model simulation than it is to directly simulate a large number of cascades with a more detailed model. Interaction-based mitigation measures are suggested to mitigate cascading failure risk by weakening key links, which can be achieved in real systems by wide area protection such as blocking of some specific protective relays. The proposed interaction quantifying method and interaction model are validated with line outage data generated by the AC OPA cascading simulations on the IEEE 118-bus system.
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