Power quality disturbances assessment during unintentional islanding scenarios. A contribution to voltage sag studies

This paper presents a novel voltage sag topology that occurs during an unintentional islanding operation (IO) within a distribution network (DN) due to large induction motors (IMs). When a fault occurs, following the circuit breaker (CB) fault clearing, transiently, the IMs act as generators due to their remanent kinetic energy until the CB reclosing takes place. This paper primarily contributes to voltage sag characterization. Therefore, this novel topology is presented, analytically modelled and further validated. It is worth mentioning that this voltage sag has been identified in a real DN in which events have been recorded for two years. The model validation of the proposed voltage sag is done via digital simulations with a model of the real DN implemented in Matlab considering a wide range of scenarios. Both simulations and field measurements confirm the voltage sag analytical expression presented in this paper as well as exhibiting the high accuracy achieved in the three-phase model adopted.Postprint (published version

A novel voltage sag approach during unintentional islanding scenarios: A survey from real recorded events

In this paper, a new voltage sag approach is analytically modelled and validated using both simulation and field measurements. The main aspect of this approach is to propose a new voltage sag feature which appears during unintentional islanding operations (IOs). The unintentional IO occurs when an induction motor is removed from the main utility following a circuit breaker (CB) clearing, transiently, the induction motors (IMs) are acting as generators maintaining the affected distribution feeder with voltage until it is reconnected. The voltage sag modelled in the current article follows an exponential form, as a matter of fact, here it will be demonstrated that the proposed model reaches satisfactorily the field measurements and evidences the dependability of the model adopted. Furthermore, it is worthwhile to note that this novel power quality (PQ) event has not been investigated yet and enhances voltage sag studies. Lastly, it is crucial to point out that all recorded events and a large amount of data needed so as to validate this transient, has been measured in a distribution network (DN) located in Spain.Postprint (published version

A novel voltage sag approach during unintentional islanding scenarios: A survey from real recorded events

In this paper, a new voltage sag approach is analytically modelled and validated using both simulation and field measurements. The main aspect of this approach is to propose a new voltage sag feature which appears during unintentional islanding operations (IOs). The unintentional IO occurs when an induction motor is removed from the main utility following a circuit breaker (CB) clearing, transiently, the induction motors (IMs) are acting as generators maintaining the affected distribution feeder with voltage until it is reconnected. The voltage sag modelled in the current article follows an exponential form, as a matter of fact, here it will be demonstrated that the proposed model reaches satisfactorily the field measurements and evidences the dependability of the model adopted. Furthermore, it is worthwhile to note that this novel power quality (PQ) event has not been investigated yet and enhances voltage sag studies. Lastly, it is crucial to point out that all recorded events and a large amount of data needed so as to validate this transient, has been measured in a distribution network (DN) located in Spain.Postprint (published version

Energy Monitoring & Management System (EMMS)

The Energy Monitoring and Management System (EMMS) is developing an electrical power meter to help make electricity more available in energy impoverished regions of the world. The meter fills a unique niche for energy tracking and regulation within micro-grid systems. The EMMS project has partners in Burkina Faso and Zimbabwe: Open Door Development (ODD), the Institut Missiologique du Sahel (IMS), and the Theological College of Zimbabwe (TCZ). Ties are also maintained on a regular basis with IEEE Smart Village for potential future widespread system implementation. Recent work on the EMMS meter has been focused on resolving the last few remaining bugs, establishing a robust communication system, and developing a centralized server-based interface which aids with meter configuration and administration. The team has also begun several future developments which include datalogging and remote access features.https://mosaic.messiah.edu/engr2021/1004/thumbnail.jp

Millimeter Wave MIMO Channel Estimation Based on Adaptive Compressed Sensing

Multiple-input multiple-output (MIMO) systems are well suited for millimeter-wave (mmWave) wireless communications where large antenna arrays can be integrated in small form factors due to tiny wavelengths, thereby providing high array gains while supporting spatial multiplexing, beamforming, or antenna diversity. It has been shown that mmWave channels exhibit sparsity due to the limited number of dominant propagation paths, thus compressed sensing techniques can be leveraged to conduct channel estimation at mmWave frequencies. This paper presents a novel approach of constructing beamforming dictionary matrices for sparse channel estimation using the continuous basis pursuit (CBP) concept, and proposes two novel low-complexity algorithms to exploit channel sparsity for adaptively estimating multipath channel parameters in mmWave channels. We verify the performance of the proposed CBP-based beamforming dictionary and the two algorithms using a simulator built upon a three-dimensional mmWave statistical spatial channel model, NYUSIM, that is based on real-world propagation measurements. Simulation results show that the CBP-based dictionary offers substantially higher estimation accuracy and greater spectral efficiency than the grid-based counterpart introduced by previous researchers, and the algorithms proposed here render better performance but require less computational effort compared with existing algorithms.Comment: 7 pages, 5 figures, in 2017 IEEE International Conference on Communications Workshop (ICCW), Paris, May 201

Challenges and complexities in application of LCA approaches in the case of ICT for a sustainable future

In this work, three of many ICT-specific challenges of LCA are discussed. First, the inconsistency versus uncertainty is reviewed with regard to the meta-technological nature of ICT. As an example, the semiconductor technologies are used to highlight the complexities especially with respect to energy and water consumption. The need for specific representations and metric to separately assess products and technologies is discussed. It is highlighted that applying product-oriented approaches would result in abandoning or disfavoring of new technologies that could otherwise help toward a better world. Second, several believed-untouchable hot spots are highlighted to emphasize on their importance and footprint. The list includes, but not limited to, i) User Computer-Interfaces (UCIs), especially screens and displays, ii) Network-Computer Interlaces (NCIs), such as electronic and optical ports, and iii) electricity power interfaces. In addition, considering cross-regional social and economic impacts, and also taking into account the marketing nature of the need for many ICT's product and services in both forms of hardware and software, the complexity of End of Life (EoL) stage of ICT products, technologies, and services is explored. Finally, the impact of smart management and intelligence, and in general software, in ICT solutions and products is highlighted. In particular, it is observed that, even using the same technology, the significance of software could be highly variable depending on the level of intelligence and awareness deployed. With examples from an interconnected network of data centers managed using Dynamic Voltage and Frequency Scaling (DVFS) technology and smart cooling systems, it is shown that the unadjusted assessments could be highly uncertain, and even inconsistent, in calculating the management component's significance on the ICT impacts.Comment: 10 pages. Preprint/Accepted of a paper submitted to the ICT4S Conferenc