Curvature-Based Control for Low-Inertia Systems

This letter proposes a simple and inexpensive control of distributed energy resources aimed at improving the power system dynamic performance. The rationale behind the proposed control relies on a recent interpretation of the frequency in the differential geometry framework. A comparison with well-established controls in terms of eigensensitivity and time-domain performance is carried out to show the effectiveness of the proposed control.Italian Ministry of EducationSustainable Energy Authority of Irelan

An Original Educational Algorithm Assessing the Behaviours of Angular Frequency Deviations of a Multimachine System in Small Signal Analysis

The paper presents a fully self-implementable algorithm that has demonstrated to be an effective tool for power education at the University of Padova-Department of Industrial Engineering. It deals with the small signal analysis of the electromechanical transients of a multimachine system. The algorithm allows analytically building both the state matrix and the input matrix. Moreover, by exploiting the matrix exponential, the angular frequency deviations of synchronous generators can be computed and plotted so to help students to evaluate transient stability. Besides the full exposition of the algorithm, the paper presents a comparison between a self-implemented linearized dynamic in Matlab environment and the dynamic simulation obtained by the commercial software DIgSILENT PowerFactory

A Novel Modeling for Assessing Frequency Behavior During a Hydro-to-Thermal Plant Black Start Restoration Test

Northern electric grid of Italy was involved in a black start mock drill. This test took place on November 2016 in order to check the coordination and efficiency of all the operational staffs and the automatic regulators involved in the case of a real blackout scenario. This paper presents the results of a research carried out in collaboration with Terna Rete Italia (the Italian Transmission System Operator), in order to find strengths and weaknesses and eventually to upgrade the existing restoration plan. Starting from the measures coming from generating plants and substations bars, the model of frequency regulation system for both the participating hydro and thermal power plants is developed. This work gives the system operator an essential tool to understand many complex dynamics and phenomena occurred during the test. At the same time, a robust model simulating the system behavior with different grid configurations is presented: it gives the opportunity to enhance both the classical power system control theory and the black start practices

Power System Restoration Modelling, Simulation and Comparison with Field Tests

This research project is focused on the modeling and simulations of the bottom-up restoration strategies. The aim is the implementation of an electromechanic and electromagnetic model totally devoted to the simulations of power system restorations, to quantify the impact of the new power system paradigm on the dynamic performance of the restoration process. With this aim, an active distribution network model is implemented to better consider the strong penetration of DERs even with their protection equipment. The model serves to conceive a procedural approach to study the restoration process from the planning to the final on-field test. The present research also includes the implementation of possible countermeasures in order to avoid some critical scenarios. The research is carried out in strong collaboration with the Italian TSO Terna, which provides a wide amount of network data and field recordings.This research project is focused on the modeling and simulations of the bottom-up restoration strategies. The aim is the implementation of an electromechanic and electromagnetic model totally devoted to the simulations of power system restorations, to quantify the impact of the new power system paradigm on the dynamic performance of the restoration process. With this aim, an active distribution network model is implemented to better consider the strong penetration of DERs even with their protection equipment. The model serves to conceive a procedural approach to study the restoration process from the planning to the final on-field test. The present research also includes the implementation of possible countermeasures in order to avoid some critical scenarios. The research is carried out in strong collaboration with the Italian TSO Terna, which provides a wide amount of network data and field recordings

Lessons Learnt from Modelling and Simulating the Bottom-Up Power System Restoration Processes

This paper aims to present the gained experience in modeling and simulating bottom-up power system restoration processes. In a system with low inertia, such as a restoration path, the Common Information Models for the regulation systems appear to no longer be suitable for the estimation of the frequency behavior, and thus a detailed model must be considered. On the other hand, due to the predominantly inductive behavior of the HV transmission network, the assumption of decoupling the power-frequency behavior to study the restoration stability seems to be licit. All these issues are discussed and justified in the paper by means of the use of different software packages and of the comparison with on-field recordings

Analysis and Explanation of Resonant Phenomena Involving EHV Transformers during Power System Restoration Tests

This paper deals with the simulation and the experimental confirmation of electromagnetic events that could interfere with the successful formation of the restoration path during the power system restoration procedure. The studied phenomena are more relevant for bulk power systems characterized by a low short circuit power as the restoration backbone. In particular, two case studies have been simulated and analyzed: one related to a transformer energization during the formation of the restoration path, and the other one occurred after the de-energization of some transmission lines and one autotransformer belonging to the restoration path. From the simulation results, it emerged that such events are related to the resonant effects between the supplying transformer and the restored network. Such resonances could have negative effects on the restoration if they are not effectively managed. In order to evaluate the impact of such phenomena in real networks, the measurement recordings of on-field tests were compared with the simulation results. It is worth noting that the performed analyses require the knowledge of several parameters that were not always available in practice. Hence, the exact magnitude of the described resonant phenomena was not easy to foresee for the restoration of real networks. The performed comparison confirms the preliminary simulation results and highlights that detailed electromagnetic models are particularly important to support the power system restoration management, in particular the planning of recovery procedures

Un modello per lo studio dei Black-Start verificato da una prova di riaccensione

L\u2019articolo presenta un metodo di simulazione sviluppato da Terna in collaborazione con il mondo universitario, utile allo studio dei complessi fenomeni dinamici che si verificano nel sistema elettrico durante una ripartenza da blackou

A Deep Convolutional Neural Network for Location Recognition and Geometry based Information

In this paper we propose a new approach to Deep Neural Networks (DNNs) based on the particular needs of navigation tasks. To investigate these needs we created a labeled image dataset of a test environment and we compare classical computer vision approaches with the state of the art in image classification. Based on these results we have developed a new DNN architecture that outperforms previous architectures in recognizing locations, relying on the geometrical features of the images. In particular we show the negative effects of scale, rotation, and position invariance properties of the current state of the art DNNs on the task. We finally show the results of our proposed architecture that preserves the geometrical properties. Our experiments show that our method outperforms the state of the art image classification networks in recognizing locations

The artero-ventricular coupling in patients undergoing cardiac resynchronization therapy (CRT).

Objectives: Despite CRT benefits, a 30% of not responders remains and a reliable criterion to define responder patients is still missing. The aim of this work was to evaluate the changes in the artero-ventricular coupling (AVC) in CRT patients (PTs), relating this index to clinical and echocardiographic outcomes. Materials & Methods: A lumped parameter computational model CRT-dedicated was used to evaluate AVC as the ratio between left ventricular elastance and arterial elastance before the implantation (B) and at the follow up (FU). 30 consecutive PTs undergoing CRT were retrospectively studied. PTs were evaluated at B and at FU (every 3 months) by ECG, echocardiography, 6 minute walk test (6MWT), aortic pressure measurement. Aortic pressure, ECG and echocardiographic parameters were set into the model at B and at FU to simulate the pathophysiological condition of PTs to evaluate AVC. PTs were considered echocardiographic (clinical) responder for a left ventricular end sistolic volume (LVESV) reduction >15% (improvement >20% of the 6MWT). The changes in AVC were compared with PTs response. Results: A statistical significant difference was evidenced between B and FU, average FU[months]=11.2?7.0: LVESV[ml]: B=185.4?90.7, FU=129.4?59.9, p=0.003; 6MWT[m]: B=131.5?113.4, FU=317.3?132.6, p<0.001; AVC: B=0.39? 0.37, FU=0.63?0.21, p=0.04. In 35% of PTs the highest AVC is reached at the 6 month FU. In 7 PTs the AVC reaches a value close to 1, that is the optimal artero-ventricular coupling. 60% of PTs showing an AVC improvement are also echocardiographic and clinical responders. In 4 cases the AVC is not in accordance with clinical and/or echocardiographic changes. Conclusions: As CRT induces both left ventricular and peripheral arterial function improvement, the evaluation of AVC can be a useful index that can be added to the criteria to define a responder