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This article proposes a novel optimal hybrid control framework to improve the voltage profile of highly unbalanced Distribution Grids (DGs) by coordinating the injection of reactive power from multiple off-board Electrical Vehicles (EVs) chargers. It exploits the time-synchronized measurements advantages, centralized control, and local controllers embedded into a hierarchical and scalable scheme, coordinated by the distribution system operator (DSO). The proposed framework is aimed to increase the modern electrical networks’ flexibility, reliability, and stability. It is powered by the Eigensystem Realization (ER)-based system identification technique, a Linear Quadratic Gaussian (LQG) controller, the Distribution-level Phasor Measurement Units (D-PMUs), and a new aggregator agent that handles the EV chargers power injection to precisely and timely regulate the dynamic voltage response in a sub-area or the entire DG. The robustness and feasibility of the proposal are demonstrated by employing simulated scenarios with unbalanced faults, latency in communications, and highly unbalanced loads conditions on the IEEE 13 and 123 nodes test feeders, compensating the voltage variations accurately in less than 205 ms. The promising outcome of this study suggests a novel application for an emerging measurement-based control system in the operation of modern active DGs. [ABSTRACT FROM AUTHOR]

Transients caused by lightning that strikes to transmission lines, switching operations or faults, are fundamentals in selecting equipment insulation levels and protection devices. Thus, studies of electromagnetic transients on transmission lines have demonstrated that when a change on the normal operation of the system takes place, voltage and currents traveling waves appear and these are reflected and refracted in the transmission line. In this paper, an ATPDraw simulator is developed to observe the propagation of voltage and current traveling waves along the transmission lines. The Bewley's Lattice diagram is used into the simulator to show in a comprehensive manner the behavior of the traveling waves. The behavior of the traveling waves is strictly depending on the reflection and refraction coefficients in the sending and receiving nodes, in turn these coefficients are depending on the transmission network's parameters, such as the characteristic impedance and the impedance of the sending and receiving ends. [ABSTRACT FROM AUTHOR]