Conference Agenda

The development of accurate equivalent models of distribution networks (DNs) is one of the most important aspects for power system dynamic analysis. Consequently, during the last decades, several equivalent models have been proposed to analyze the dynamic behavior of DNs. However, the performance of existing models is sensitive to several factors such as the pre-disturbance operating conditions and the penetration level of distributed generators. Scope of this paper is to evaluate the applicability range of conventional equivalent models for the dynamic analysis of modern DNs by using a recently proposed performance assessment method. Towards this objective, the performance, in terms of accuracy and generalization capability, of 22 conventional equivalent models is assessed. Finally, the most critical parameters of all examined equivalents are identified by applying a variance-based sensitivity analysis.

Distribution feeders are prone to different types of events, such as disturbances and faults. Since these events are both unwanted and unexpected, their detection is essential for prompt system restoration, ensuring its reliability. This paper proposes the use of a power component, defined for non-sinusoidal conditions, as a disturbance detection index, which is estimated using the real-time stationary discrete wavelet packet transform. The proposed method analyzes the voltage and current of each phase separately, which are acquired at a single upstream measurement point, the substation. The performance and effectiveness of the proposed method are evaluated using events simulated in a test system based on a real distribution network. The results attest that the proposed method is suitable for detecting non-stationary disturbances.

Thereplacement of conventional synchronous gener-ators with converter-interfaced renewable energy sources (RESs)reduces the overall inertia levels of modern power systems,leading to frequency stability issues. Moreover, the intermittentnature of RESs constitutes system inertia variable during the day,further complicating the frequency control procedure. Therefore,power system operators shall estimate close to real-time theoverall inertia levels of their grids in order to ensure theirsecure and reliable operation. In this context, in this paper, anew methodology for the inertia estimation of multi-area powersystems is formulated. The proposed method uses the modalsensitivity matrix to obtain a linear approximation of the relationbetween modal parameters and inertia constants. During thereal-time operation, modal parameters are identified via systemresponses using the Matrix Pencil method. The identified modesand the derived sensitivity matrix are used to estimate the overallinertia of the examined power system. The effectiveness of theproposed method is validated by means of simulations performedin one-area, two-area, and three-area power system models.

Electricity is currently one of the most promising components for the future growth of our communities. Energy consumption will skyrocket in the near future, necessitating massive reforms in the energy industry to ensure that contemporary cities have enough electricity. Furthermore, climate change necessitates a greater than ever before energy transition from fossil fuels to greener power generating sources such as wind, solar power, or other more newly discovered technologies such as hydrogen. However, significant improvements to the power distribution and transmission grids are required for high - RES penetration in the energy system. To illustrate, power networks have been built radially, with energy flowing in just one direction, from the original power source to the consumer, with no provision for the penetration of independent power producers (ipps) across power grids. As a result, studying and developing such significant components, including power protection systems, is now seen as a critical undertaking in order to minimize unanticipated breakdowns and optimize grid availability. The goal of this work is to analyze a novel and promising technology in the power protection industry known as Solid State Breakers (SSB) and its contribution to the efficient operation of power distribution networks with high-RES penetration.

This paper evaluates the modeling of guyed towers of transmission lines in EMT-type programs to assess the backflashover occurrence of transmission lines and proposes a new modeling approach for this kind of towers. Two approaches to model the guyed towers by the revised Jordan model were evaluated: (i) the approach suggested by CIGRE Brochure 63 that represents the tower surge impedance as the parallel of the surge impedances of the mast and the guyed wires, disregarding the mutual coupling among them, and (ii) a new approach assuming the surge impedance of all the conductors in the tower section, guyed and mast conductors, and their mutual effect. The evaluations assumed the results provided by the Hybrid Electromagnetic Model (HEM) as reference for assessing the quality of the approaches. The approach (i) provided results of lightning overvoltage significantly lower than the reference, HEM model, leading to an underestimation of the probability of backflashover of the line. On the other hand, the approach (ii) was responsible for the results closest to those provided by HEM, indicating its quality, and the recommendation of applying this proposed approach for modeling guyed towers in the evaluations of backflashover occurrence.

Massive integration of power electronic devices with multiple control schemes in a wide frequency range pose new challenges regarding systems stability and reliability. Interactions between the fast control loops or between the fast control loops and passive elements of the grid, have been reported in literature and have led to introducing a new type of stability: the Fast-Interaction Converter-driven Stability (FICDS). In this paper, factors affecting the FICDS, such as tuning controller parameters, line parameters, number of interconnected inverters, are explored in four microgrid topologies, operating in grid connected and islanded mode. With the use of an impedance based model which tracks the poles of the CDS transfer functions of each system, their stability has been assessed. The obtained results have been verified via timedomain simulations. Simulations from the islanded microgrid of Gaidouromantra in Greece showcase the impact of the control parameters on the operation of the system and indicate the need for further investigation.