Transient stabilization of multimachine power systems with nontrivial transfer conductances

Published versio

Generalized Parameter Estimation-based Observers: Application to Power Systems and Chemical-Biological Reactors

In this paper we propose a new state observer design technique for nonlinear systems. It consists of an extension of the recently introduced parameter estimation-based observer, which is applicable for systems verifying a particular algebraic constraint. In contrast to the previous observer, the new one avoids the need of implementing an open loop integration that may stymie its practical application. We give two versions of this observer, one that ensures asymptotic convergence and the second one that achieves convergence in finite time. In both cases, the required excitation conditions are strictly weaker than the classical persistent of excitation assumption. It is shown that the proposed technique is applicable to the practically important examples of multimachine power systems and chemical-biological reactors.Comment: 13 pages, 8 figure

Robust Hamiltonian passive control for higher relative degree outpus

We present an improvement of the well-know Interconnection and Damping Assignment-Passivity-based Control (IDA-PBC) technique. The IDA-PBC method is based on the Port –controlled Hamiltonian Systems description and requires the knowledge of the full energy (or Hamiltonian) function. This is a problem because, in general, the equilibrium point which is to be regulated depends on uncertain parameters. In this paper, we show how select the target port-Hamiltonian structure so that this dependence is reduced. This new approach allows to improve the robustness for higher relative degree outputs, and, for illustration purposes, is applied to a simple academic nonlinear syste

Synchronization and Transient Stability in Power Networks and Non-Uniform Kuramoto Oscillators

Motivated by recent interest for multi-agent systems and smart power grid architectures, we discuss the synchronization problem for the network-reduced model of a power system with non-trivial transfer conductances. Our key insight is to exploit the relationship between the power network model and a first-order model of coupled oscillators. Assuming overdamped generators (possibly due to local excitation controllers), a singular perturbation analysis shows the equivalence between the classic swing equations and a non-uniform Kuramoto model. Here, non-uniform Kuramoto oscillators are characterized by multiple time constants, non-homogeneous coupling, and non-uniform phase shifts. Extending methods from transient stability, synchronization theory, and consensus protocols, we establish sufficient conditions for synchronization of non-uniform Kuramoto oscillators. These conditions reduce to and improve upon previously-available tests for the standard Kuramoto model. Combining our singular perturbation and Kuramoto analyses, we derive concise and purely algebraic conditions that relate synchronization and transient stability of a power network to the underlying system parameters and initial conditions

Об управлении энергосистемами в условиях импульсного воздействия

Для модели управляемой импульсной электроэнергетической системы с запаздыванием и импульсным воздействием предложен подход к исследованию устойчивости с использованием неограниченной кусочно-линейной функции Ляпунова. На основе разработанного подхода получены достаточные условия асимптотической устойчивости системы.Для моделi керованої iмпульсної електроенергетичної системи з запiзненням та iмпульсною дiєю запропоновано пiдхiд до дослiдження стiйкостi з використанням необмеженої кусково-лiнiйної функцiї Ляпунова. На основi розробленого пiдходу отримано достатнi умови асимптотичної стiйкостi системи.For an impulsive delay model of electric power system with control a new approach for stability analysis by using unbounded piecewise-linear Lyapunov function has been proposed. Sufficient conditions of asymptotical stability for the system has been established by using this approach

Optimal power dispatch in networks of high-dimensional models of synchronous machines

This paper investigates the problem of optimal frequency regulation of multi-machine power networks where each synchronous machine is described by a sixth order model. By analyzing the physical energy stored in the network and the generators, a port-Hamiltonian representation of the multi-machine system is obtained. Moreover, it is shown that the open-loop system is passive with respect to its steady states which implies that passive controllers can be used to control the multi-machine network. As a special case, a distributed consensus based controller is designed that regulates the frequency and minimizes a global quadratic generation cost in the presence of a constant unknown demand. In addition, the proposed controller allows freedom in choosing any desired connected undirected weighted communication graph.Comment: 7 pages, submitted to Conference on Decision and Control 201

A Framework for Robust Assessment of Power Grid Stability and Resiliency

Security assessment of large-scale, strongly nonlinear power grids containing thousands to millions of interacting components is a computationally expensive task. Targeting at reducing the computational cost, this paper introduces a framework for constructing a robust assessment toolbox that can provide mathematically rigorous certificates for the grids' stability in the presence of variations in power injections, and for the grids' ability to withstand a bunch sources of faults. By this toolbox we can "off-line" screen a wide range of contingencies or power injection profiles, without reassessing the system stability on a regular basis. In particular, we formulate and solve two novel robust stability and resiliency assessment problems of power grids subject to the uncertainty in equilibrium points and uncertainty in fault-on dynamics. Furthermore, we bring in the quadratic Lyapunov functions approach to transient stability assessment, offering real-time construction of stability/resiliency certificates and real-time stability assessment. The effectiveness of the proposed techniques is numerically illustrated on a number of IEEE test cases