167 research outputs found
Geometry-based Estimation of Stability Region for A Class of Structure Preserving Power Grids
The increasing development of the electric power grid, the largest engineered
system ever, to an even more complicated and larger system requires a new
generation of stability assessment methods that are computationally tractable
and feasible in real-time. In this paper we first extend the recently
introduced Lyapunov Functions Family (LFF) transient stability assessment
approach, that has potential to reduce the computational cost on large scale
power grids, to structure-preserving power grids. Then, we introduce a new
geometry-based method to construct the stability region estimate of power
systems. Our conceptual demonstration shows that this new method can certify
stability of a broader set of initial conditions compared to the
minimization-based LFF method and the energy methods (closest UEP and
controlling UEP methods)
Lyapunov Functions Family Approach to Transient Stability Assessment
Analysis of transient stability of strongly nonlinear post-fault dynamics is
one of the most computationally challenging parts of Dynamic Security
Assessment. This paper proposes a novel approach for assessment of transient
stability of the system. The approach generalizes the idea of energy methods,
and extends the concept of energy function to a more general Lyapunov Functions
Family (LFF) constructed via Semi-Definite-Programming techniques. Unlike the
traditional energy function and its variations, the constructed Lyapunov
functions are proven to be decreasing only in a finite neighborhood of the
equilibrium point. However, we show that they can still certify stability of a
broader set of initial conditions in comparison to the traditional energy
function in the closest-UEP method. Moreover, the certificates of stability can
be constructed via a sequence of convex optimization problems that are
tractable even for large scale systems. We also propose specific algorithms for
adaptation of the Lyapunov functions to specific initial conditions and
demonstrate the effectiveness of the approach on a number of IEEE test cases
Towards Electronics-based Emergency Control in Power Grids with High Renewable Penetration
Traditional emergency control schemes in power systems usually accompany with
power interruption yielding severely economic damages to customers. This paper
sketches the ideas of a viable alternative for traditional remedial controls
for power grids with high penetration of renewables, in which the renewables
are integrated with synchronverters to mimic the dynamics of conventional
generators. In this novel emergency control scheme, the power electronics
resources are exploited to control the inertia and damping of the imitated
generators in order to quickly compensate for the deviations caused by fault
and thereby bound the fault-on dynamics and stabilize the power system under
emergency situations. This emergency control not only saves investments and
operating costs for modern and future power systems, but also helps to offer
seamless electricity service to customers. Simple numerical simulation will be
used to illustrate the concept of this paper.Comment: arXiv admin note: text overlap with arXiv:1504.0468
Synchronization stability of lossy and uncertain power grids
Direct energy methods have been extensively developed for the transient stability analysis and contingency screening of power grids. However, there is no analytical energy functions proposed for power grids with losses, which are normal in practice. This paper applies the recently introduced Lyapunov Functions Family approach to the certification of synchronization stability for lossy power grids. This technique does not rely on the global decreasing of the Lyapunov function as in the direct energy methods, and thus is possible to deal with the lossy power grids. We show that this approach is also applicable to uncertain power grids where the stable equilibrium is unknown due to possible uncertainties in system parameters. We formulate this new control problem and introduce techniques to certify the robust stability of a given initial state with respect to a set of equilibria
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