Conference Agenda

Timely detection and classification of power system events are essential for situation awareness and reliable electricity grid operation. It is also a crucial step with regard to synchrophasor network data management and archiving. In this paper, an event detection and classification method based on the singular value decomposition (SVD) of synchrophasor data is proposed. The detection algorithm exploits the low-dimensionality characteristics of synchrophasor data and identifies the changes in the dimensionality of a sliding data matrix. The SVD-based method assigns several detection flags indicating events and outliers in voltage magnitude, phase angle and frequency data. The proposed classification algorithm comprises a decision tree employing detection flags and singular values to classify events into several categories, e.g., fault, voltage magnitude and phase angle events, and generation-load mismatch events. Moreover, the proposed algorithm identifies whether events are spatially correlated. Field synchrophasor data collected from a smart grid are used to evaluate the performance of the proposed method. The numerical results show that the proposed method can successfully detect and classify different types of events even in the presence of measurement uncertainty.

In today's grid reinforcement in Germany, more and more underground cable sections are being installed at the 400-kV level. They are mostly used near cities or to overcome other obstacles. Consequently, mixed transmission lines are formed, which include overhead line and cable sections at this voltage level. Typically, shunt reactors are used on such lines to compensate the capacitive reactive power. In addition to the compensation degree, the type of the reactor is also important. These can be realized as an air core coil or as a coil with iron core. Especially when using iron core coils there are additional effects like saturation or zero-missing effects, which have to be investigated before erecting a mixed transmission line. These effects are numerically simulated and validated and explained using an analytical method. With the aid of a simplified model, the system properties have been investigated and applied to the transmission line.

A phase-domain synchronous machine modeling technique by using only basic circuit components and applying the magnetic circuit representation used for transformer modeling is proposed in this paper. The model based on the proposed technique is implemented into XTAP, one of the electromagnetic transient analysis programs, and the accuracy of the proposed model is validated through simulation in an infinite-bus case system by comparing it with some conventional synchronous machine models in this paper.

In this paper, a new method for on-line inertiaestimation is developed. The proposed method is based onthe sliding window concept and uses ambient responses, i.e.,responses obtained during the normal operation of the powersystem, to identify inertia constants of generation devices. Theeffectiveness of the developed method is evaluated by means ofsimulations on two benchmark power system models, namelythe IEEE 9-Bus Test System and the IEEE 39-Bus Test System.The conducted analysis reveals that the proposed method canaccurately identify inertia constants of conventional synchronousgenerators (SGs), converter-interfaced units operated as virtualSGs, and virtual power plants. The performance of the proposedmethod is also evaluated under noisy conditions, by performingMonte Carlo simulations. Finally, comparisons with conventionalmethods are performed, demonstrating the superior performanceof the developed method.

Voltage dividers are devices designed to reduce high voltages according to a transformation ratio to facilitate their measurement for different purposes. Among them is the detection of transient overvoltages in medium voltage lines. It is convenient to know the transformation ratio of the sensor and its working frequency range for the correct measurement of overvoltages. This article shows the characterization process of an air-insulated capacitive voltage divider used to measure induced voltages in distribution networks. A detailed description of the device is shown, such as how it works and the tests carried out for its characterization. The parameters of its equivalent circuit are obtained by modeling the voltage divider in the CST Studio 2021 software; through laboratory tests, its experimental transformation ratio is obtained; and through a frequency sweep applied to the divider, its frequency response is determined. Indeed, the experimental transformation ratio is 10667.46:1, and the frequency range obtained experimentally is between 60 Hz and 4 MHz, different data from those given by the manufacturer. These experimental data can be used as a reference for the capacitive voltage divider.

In islanded hybrid AC/DC multi-microgrids (MMGs), interconnected AC microgrids (ACMGs) can operate with their own frequency and power sharing strategy. Hence, to formulate the load-flow problem of multi-frequency islanded MMGs, conventional single-frequency load-flow approaches are
not applicable. To this aim, in this paper a novel unified load-flow framework for AC/DC hybrid MMGs, is proposed. The principles of the proposed method are based on the modified augmented
nodal analysis (MANA) formulation, which can be utilized for an arbitrary number of interconnected multiphase MGs. Then, an unbalanced MMG, which includes two ACMGs, one DC MG (DCMG), and two interlink converters (ICs), is used to verify the validity of the proposed MANA-based formulation.