In this paper a novel methodology for evaluating the external equivalent model of a distributed network is presented. The proposed method is based on a non-linear parameter identification process which involves an artificial dynamic system, whose dynamics are explicitly designed to be stable by adopting the Lyapunov theory. This dynamic identificationmethod is competitive with existing reductionmethods, since it does not require system linearization or any a priori information about the system under study. Few measurements at boundary nodes are required to obtain the essential information regarding the external system. Even if these measurements are strongly corrupted by noise, the algorithm is quite insensible to it. Due to its ability to be auto-adaptive at any changes in the system operating conditions and to its great speed convergence, the identification procedure can be usefully applied for real-time applications.

This paper proposes an auto-adaptive controller that enables to suitably manage the reactive power supplied by the inverters of PV units whishing to provide the reactive power ancillary service on the base of standard needs or on a voluntary basis. The derived controller is based on an optimization procedure involving the sensitivity theory in conjunction with the Lyapunov function and provides control laws feeding the inverters of the PV units. The controller promptly minimizes system losses preserving the active power produced by the PV plants against the reactive one. In fact, when the PV modules do not get enough sunlight to generate active power, the proposed procedure forces the PV inverters to provide a reactive power equal to the rated power. On the contrary, in order to preserve the major economic benefits for the investor deriving from the produced active power during the sunlight hours, the method automatically reduces the injection of reactive power. The computer simulations, performed on a distribution system, demonstrate that the controller is capable to control the network in the real-time, mainly due to its ability to be auto-adaptive at any changes in the system operating conditions.

The characteristic ellipsoid (CELL) method to monitor dynamic behaviors of a power system is proposed. Multi-dimensional minimum-volume-enclosing characteristic ellipsoids are built using synchronized phasor measurements. System dynamic behaviors are identified by tracking the change rate of the CELL’s characteristic indices. Decision tree techniques are used to link the CELL’s characteristic indices and the system’s dynamic behaviors and to determine types, locations and related information about the dynamic behaviors. The knowledge base of representative transient events is created by offline simulations based on the full Western Electric Coordinating Council (WECC) model. Two case studies demonstrate that the CELL method combined with the decision trees can detect transient events and their features with good accuracy.

This paper aims to analyze Variable Speed Wind Turbine impact on transient behavior of a power system using time domain simulation. To this purpose, suitable mathematical models for Doubly Fed Induction Generators and Permanent Magnet Synchronous Generators with their control devices are considered. Simulations allow to assess the influence of VSWT on conventional synchronous generator dynamics after short-circuit fault occurrence.

An extreme flexibility of a microgrid operation requires general, integrated and hierarchical proper management and control systems. A wide variety of communication technologies from communication medias, communication protocols to sensors and algorithms are available for microgrid applications. The requirements of communication capabilities differ with the varying microgrid architectures, physical scales, control strategies, functions. In this paper, typical communication protocols are applied to the layout of an experimental microgrid (MG). A hierarchical control is then implemented in order to allow primary and secondary generation unit regulation of the MG.