Output Impedance Diffusion into Lossy Power Lines

Output impedances are inherent elements of power sources in the electrical grids. In this paper, we give an answer to the following question: What is the effect of output impedances on the inductivity of the power network? To address this question, we propose a measure to evaluate the inductivity of a power grid, and we compute this measure for various types of output impedances. Following this computation, it turns out that network inductivity highly depends on the algebraic connectivity of the network. By exploiting the derived expressions of the proposed measure, one can tune the output impedances in order to enforce a desired level of inductivity on the power system. Furthermore, the results show that the more "connected" the network is, the more the output impedances diffuse into the network. Finally, using Kron reduction, we provide examples that demonstrate the utility and validity of the method

Synchronization of Nonlinear Circuits in Dynamic Electrical Networks with General Topologies

Sufficient conditions are derived for global asymptotic synchronization in a system of identical nonlinear electrical circuits coupled through linear time-invariant (LTI) electrical networks. In particular, the conditions we derive apply to settings where: i) the nonlinear circuits are composed of a parallel combination of passive LTI circuit elements and a nonlinear voltage-dependent current source with finite gain; and ii) a collection of these circuits are coupled through either uniform or homogeneous LTI electrical networks. Uniform electrical networks have identical per-unit-length impedances. Homogeneous electrical networks are characterized by having the same effective impedance between any two terminals with the others open circuited. Synchronization in these networks is guaranteed by ensuring the stability of an equivalent coordinate-transformed differential system that emphasizes signal differences. The applicability of the synchronization conditions to this broad class of networks follows from leveraging recent results on structural and spectral properties of Kron reduction---a model-reduction procedure that isolates the interactions of the nonlinear circuits in the network. The validity of the analytical results is demonstrated with simulations in networks of coupled Chua's circuits

Modelling and control for bounded synchronization in multi-terminal VSC-HVDC transmission networks

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The extension and size of the power grid is expected to increase in the near future. Managing such a system presents challenging control problems that, so far, have been approached with classical control techniques. However, large scale systems of interconnected nodes fall within the framework of the emerging field of complex networks. This paper models multi-terminal VSC-HVDC systems as a complex dynamical network, and derives conditions ensuring bounded synchronization of its trajectories for a family of controllers. The obtained results are validated via numerical simulations.Postprint (author's final draft

Analysis of consensus-based islanded microgrids subject to unexpected electrical and communication partitions

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksMicrogrids are power systems consisting of an electrical network composed by distributed loads and generation units that may include a communication network for improved operation. The considered microgrid in islanded mode is driven by voltage source inverters implementing decentralized droop control for active power sharing together with a communication-based consensus algorithm for frequency regulation. This paper analyses the microgrid performance subject to network failures that provoke network partitions. It is considered that the electrical partition leads to several sub-microgrids working in parallel where the power demand can be always guaranteed by the generation units, and the communication partition leads to several consensus algorithms also working in parallel. The double partitioning is analyzed through a closed-loop system model derived using the power flow equations that includes the electrical and communication connectivity. Analytical expressions for the steady-state values for both frequency and active power depending on the partitioning are derived. Selected experimental results on a low-scale laboratory microgrid illustrate the (undesirable) impact that unexpected partitions have in system performancePeer ReviewedPostprint (author's final draft

A Novel Reduced Model for Electrical Networks With Constant Power Loads

We consider a network-preserved model of power networks with proper algebraic constraints resulting from constant power loads. Both for the linear and the nonlinear differential algebraic model of the network, we derive explicit reduced models which are fully expressed in terms of ordinary differential equations. For deriving these reduced models, we introduce the "projected incidence" matrix which yields a novel decomposition of the reduced Laplacian matrix. With the help of this new matrix, we provide a complementary approach to Kron reduction, which is able to cope with constant power loads and nonlinear power flow equations

Modelamiento de la dinámica de microrredes aisladas controladas por Consensus

Modelar la dinámica de microrredes aisladas controladas por el método consensus.Las microrredes son sistemas usados en la distribución y generación de electricidad, que pueden estar conectadas a la red principal o trabajar en forma aislada, a diferencia de una red tradicional. En el modo aislado la red principal no tiene ningún efecto en la dinámica de la microrred, por lo tanto es necesario igualar la relación de oferta - demanda mediante técnicas de control. La estructura de operación estándar de una microrred aislada se basa en un nivel de control primario que puede ser “droop” y un nivel de control secundario de entre otros métodos reluce “consensus”. Este trabajo abarca el modelado de la dinámica de una microrred de cuatro nodos controlado mediante droop – consensus, considerando solamente la compartición de potencia y frecuencia. Por medio de la herramienta Matlab, junto con Simulink y TrueTime se simula la microrred donde se analiza la partición en la red eléctrica y de comunicación. Como resultado se obtiene que cuando existe una partición en la red eléctrica se logra una distribución de potencia y regulación de frecuencia aceptable, mientras que cuando existe una partición en la red de comunicación se pierde la compartición de potencia.Ingenierí