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In this paper, we formulate the economic dispatch problem as a two-stage stochastic convex program for operational decision making under uncertainty. Post-contingency minimum frequency constraints are formulated as convex sets using a simplified model of frequency dynamics. The L-shaped method is used to decompose the large stochastic program into smaller sub-problems. Large-scale system examples...
Wind generator (WG) output is a function of wind speed and three-phase terminal voltage. Distribution systems are predominantly unbalanced. A WG model that is purely a function of wind speed is simple to use with unbalanced three-phase power flow analysis but the solution is inaccurate. These errors add up and become pronounced when a single three-phase feeder connects several WGs. Complete nonlinear...
This paper proposes an accurate and precise Genetic Algorithm (GA) for frequency estimation of Electrical Power System (EPS) signals. The problem of estimating the frequency of a distorted electrical signal is modeled as an optimization problem. A regularization technique is used to guide the GA to a plausible solution from a practical point of view when the signal has significant output distortions...
This paper describes a stochastic “Random Chemistry” (RC) algorithm to identify multiple (n-k) contingencies that initiate large cascading failures in a simulated power system. The method requires only O(log(n)) simulations per contingency identified, which is orders of magnitude faster than random search of this combinatorial space. We applied the method to a model of cascading failure in a power...
In this paper, it is shown that analyzing the subsynchronous oscillation (SSO) damping effectiveness of an induction machine damping unit (IMDU) only based on its torque-slip characteristic curve is not adequate. A method to directly calculate the electrical damping of an IMDU according to its parameters, which is fast and accurate, is developed. This direct calculation method makes it possible to...
An online hardware-in-the-loop finite-element (FE)-based design optimization procedure is developed for the computational prototyping of coupled electric motor-drive system. A design optimization case for development of permanent magnet (PM) machine drive is presented. The physical representation of the machine is achieved by modeling the machine as a current adjustable load. The mutual interaction...
This paper presents a mixed-integer linear programming (MILP) formulation of start-up (SU) and shut-down (SD) power trajectories of thermal units. Multiple SU power-trajectories and costs are modeled according to how long the unit has been offline. The proposed formulation significantly reduces the computational burden in comparison with others commonly found in the literature. This is because the...
Interfacing machine models in either nodal analysis-based (EMTP-like) or state variable-based transient simulation programs plays an important role in numerical accuracy and computational performance of the overall simulation. As an advantageous alternative to the traditional qd models, a number of advanced phase-domain (PD) and voltage-behind-reactance (VBR) machine models have been recently introduced...
Transient simulation programs, either nodal analysis-based (EMTP-like) or state-variable-based, are used very extensively for modeling and simulation of various power and energy systems with electrical machines. It has been shown in the literature that the method of interfacing machine models with the external electrical network plays an important role in numerical accuracy and computational performance...
This paper generalizes the recently introduced bilinear formulation of the WLS state estimation problem to those cases in which equality constraints must be explicitly considered. This leads to augmented equation systems in which both state variables and Lagrange multipliers get updated throughout the three stages arising in the bilinear approach (two linear filters with a nonlinear transformation...
This paper proposes a method to allocate resources in power distribution planning and also introduces a new reliability index category, RT, flexibility to adjust to different laws or distribution system operator (DSO) policies of long outages. Possible legal consequences for distribution system operators are first identified and studied. A vulnerability-analysis method is introduced, including a statistical...
This paper presents a new concept of air-core transformers, which uses a resonant tertiary winding to create a strong coupling between the primary and secondary transformer windings. A large “magnetizing” impedance is achieved because of the resonance. Experimental and analytical studies are carried out on a toroidal air-core transformer to assess the effectiveness of the concept. The results show...
Efficient and well-timed investments in electric transmission networks that cope with the large ongoing power market uncertainties are currently an open issue of significant research interest. Strategic flexibility for seizing opportunities and cutting losses contingent upon an unfavorable unfolding of the long-term uncertainties is an attribute of enormous value when assessing irreversible investments...
Stochastic optimal power flow can provide the system operator with adequate strategies for controlling the power flow to maintain secure operation under stochastic parameter variations. One limitation of stochastic optimal power flow has been that only limits on line flows have been used as stability constraints. In many systems voltage stability and small-signal stability also play an important role...
Bridging the gap between the theoretical modeling and the practical implementation is always essential for fault detection, classification, and location methods in a power transmission-line network. In this paper, a novel hybrid framework that is able to rapidly detect and locate a fault on power transmission lines is presented. The proposed algorithm presents a fault discrimination method based on...
This paper presents a general methodology for analysis of sub-synchronous interaction in wind power plants. These include appropriate frequency scanning method for the assessment of the sub-synchronous control interaction, and calculation of the electrical damping provided by the wind turbine generator for investigation of the sub-synchronous torsional interaction. A general formulation of both methods...
In this paper, a steady-state multi-terminal voltage source converter high voltage direct current (VSC MTDC) model is introduced. The proposed approach is extended to include multiple AC and DC grids with arbitrary topologies. The DC grids can thereby interconnect arbitrary buses in one or more non-synchronized AC systems. The converter equations are derived in their most general format and correctly...
In this paper, a modeling technique for small-signal stability assessment of unbalanced power systems is presented. Since power distribution systems are inherently unbalanced, due to its lines and loads characteristics, and the penetration of distributed generation into these systems is increasing nowadays, such a tool is needed in order to ensure a secure and reliable operation of these systems....
This paper studies a LCL (inductor-capacitor-inductor) VSC AC/DC converter concept which can be employed as high power static converter. The converter is designed to have fault current near or below the rated value under the DC side short circuits. This is very important for applications with HVDC and in particular with high power DC transmission networks. This converter is composed of an AC/DC IGBT-based...
This paper investigates the potential of using battery energy storage systems in the public low-voltage distribution grid, to defer upgrades needed to increase the penetration of photovoltaics (PV). A multiobjective optimization method is proposed to visualize the trade-offs between three objective functions: voltage regulation, peak power reduction, and annual cost. The method is applied to a near-future...
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