Interaction analysis in islanded power systems with HVDC interconnections

Postprint (published version

Centralised and distributed optimization for aggregated flexibility services provision

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThe recent deployment of distributed battery units in prosumer premises offer new opportunities for providing aggregated flexibility services to both distribution system operators and balance responsible parties. The optimization problem presented in this paper is formulated with an objective of cost minimization which includes energy and battery degradation cost to provide flexibility services. A decomposed solution approach with the alternating direction method of multipliers (ADMM) is used instead of commonly adopted centralised optimization to reduce the computational burden and time, and then reduce scalability limitations. In this work we apply a modified version of ADMM that includes two new features with respect to the original algorithm: first, the primal variables are updated concurrently, which reduces significantly the computational cost when we have a large number of involved prosumers; second, it includes a regularization term named Proximal Jacobian (PJ) that ensures the stability of the solution. A case study is presented for optimal battery operation of 100 prosumer sites with real-life data. The proposed method finds a solution which is equivalent to the centralised optimization problem and is computed between 5 and 12 times faster. Thus, aggregators or large-scale energy communities can use this scalable algorithm to provide flexibility services.Peer ReviewedPostprint (published version

Stability and interaction analysis in islanded power systems including VSC-HVDC and LCC-HVDC power converters

Islanded power systems are often connected to larger mainland power systems using HVDC cables. These interconnections are used to import power at lower cost compared to local generation and improve the security of supply. The increase of HVDC interconnectors in islanded systems will allow the reduction of local synchronous generation, which might lead to new interaction and stability problems due to the low inertia and short-circuit power available in the system. Traditionally LCC-HVDC technology has been used to connect island grids, but recently VSCs are presented as an alternative solution that offers more controllability to the islanded grid. Therefore, in order to increase the power transfer to the islands multi-infeed hybrid HVSC systems with VSCs and LCCs might become a common solution. The introduction of VSCs in islanded systems will allow operations in weak grids, but possible interactions with LCCs must be analysed in detail. This paper introduces the potential interactions in multi-infeed HVDC systems with LCCs and VSCs. An initial benchmark model of an islanded power system with a LCC and a VSC-HVDC link is presented to analyse new interaction phenomena between the converters and the islanded AC grid. Simulation results in PSCAD/EMTDC are presented to validate the benchmark model for voltage stability and commutation failure analysis.Postprint (published version

Clinical consensus recommendations regarding non-invasive respiratory support in the adult patient with acute respiratory failure secondary to SARS-CoV-2 infection

La enfermedad por coronavirus 2019 (COVID-19) es una infección del tracto respiratorio causada por un nuevo coronavirus emergente que se reconoció por primera vez en Wuhan, China, en diciembre de 2019. Actualmente la Organización Mundial de la Salud (OMS) ha definido la infección como pandemia y existe una situación de emergencia sanitaria y social para el manejo de esta nueva infección. Mientras que la mayoría de las personas con COVID-19 desarrollan solo una enfermedad leve o no complicada, aproximadamente el 14% desarrollan una enfermedad grave que requiere hospitalización y oxígeno, y el 5% pueden requerir ingreso en una unidad de cuidados intensivos. En casos severos, COVID-19 puede complicarse por el síndrome de dificultad respiratoria aguda (SDRA), sepsis y shock séptico y fracaso multiorgánico. Este documento de consenso se ha preparado sobre directrices basadas en evidencia desarrolladas por un panel multidisciplinario de profesionales médicos de cuatro sociedades científicas españolas (Sociedad Española de Medicina Intensiva y Unidades Coronarias [SEMICYUC], Sociedad Española de Neumología y Cirugía Torácica [SEPAR], Sociedad Española de Urgencias y Emergencias [SEMES], Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor [SEDAR]) con experiencia en el manejo clínico de pacientes con COVID-19 y otras infecciones virales, incluido el SARS, así como en sepsis y SDRA. El documento proporciona recomendaciones clínicas para el soporte respiratorio no invasivo (ventilación no invasiva, oxigenoterapia de alto flujo con cánula nasal) en cualquier paciente con presentación sospechada o confirmada de COVID-19 con insuficiencia respiratoria aguda. Esta guía de consenso debe servir como base para una atención optimizada y garantizar la mejor posibilidad de supervivencia, así como permitir una comparación fiable de las futuras intervenciones terapéuticas de investigación que formen parte de futuros estudios observacionales o de ensayos clínicos.Coronavirus disease 2019 (COVID-19) is a respiratory tract infection caused by a newly emergent coronavirus, that was first recognized in Wuhan, China, in December 2019. Currently, the World Health Organization (WHO) has defined the infection as a global pandemic and there is a health and social emergency for the management of this new infection. While most people with COVID-19 develop only mild or uncomplicated illness, approximately 14% develop severe disease that requires hospitalization and oxygen support, and 5% require admission to an intensive care unit. In severe cases, COVID-19 can be complicated by the acute respiratory distress syndrome (ARDS), sepsis and septic shock, and multiorgan failure. This consensus document has been prepared on evidence-informed guidelines developed by a multidisciplinary panel of health care providers from four Spanish scientific societies (Spanish Society of Intensive Care Medicine [SEMICYUC], Spanish Society of Pulmonologists [SEPAR], Spanish Society of Emergency [SEMES], Spanish Society of Anesthesiology, Reanimation, and Pain [SEDAR]) with experience in the clinical management of patients with COVID-19 and other viral infections, including SARS, as well as sepsis and ARDS. The document provides clinical recommendations for the noninvasive respiratory support (noninvasive ventilation, high flow oxygen therapy with nasal cannula) in any patient with suspected or confirmed presentation of COVID-19 with acute respiratory failure. This consensus guidance should serve as a foundation for optimized supportive care to ensure the best possible chance for survival and to allow for reliable comparison of investigational therapeutic interventions as part of randomized controlled trials

Implementation of a power hardware in the loop platform with a real time power flow calculation using PSS\E

A Power Hardware in the Loop (PHIL) platform implementation for performing real time simulations of electric systems is proposed. The test bench consists of a PSS R © E real time power flow calculation in combination with a controlled grid emulator. Experimental results are presented to demonstrate the performance of the platfor

Implementation of a power hardware in the loop platform with a real time power flow calculation using PSS\E

A Power Hardware in the Loop (PHIL) platform implementation for performing real time simulations of electric systems is proposed. The test bench consists of a PSS R © E real time power flow calculation in combination with a controlled grid emulator. Experimental results are presented to demonstrate the performance of the platformPostprint (published version

Implementation of a power hardware in the loop platform with a real time power flow calculation using PSS\E

A Power Hardware in the Loop (PHIL) platform implementation for performing real time simulations of electric systems is proposed. The test bench consists of a PSS R © E real time power flow calculation in combination with a controlled grid emulator. Experimental results are presented to demonstrate the performance of the platfor

Multiport interline current flow controller for meshed HVDC grids

In meshed high voltage direct current grids, the current of each line cannot be controlled independently, since it depends on the resistances between nodes. Additional devices, such as current flow controllers (CFCs), may be needed to avoid bottlenecks or line overloads. This work presents a multiport dc-dc-based CFC topology to be connected to n lines with unidirectional current flows. The device is able to control the dc lines' currents to the desired value by inserting variable voltage sources in series. First, the modeling of the generic n-port topology is presented and then, its modulation and control strategy are described. In the first case study, the concept is validated considering a 5-port CFC by means of dynamic simulations using different control methods. Finally, in the second case study, a 3-port CFC prototype is built and tested in an experimental platform in the laboratory considering different control modes.Peer ReviewedPostprint (published version

Coordinated control design of the voltage and current loop of a current flow controller for meshed HVDC grids

This paper is focused in the control design of a DC/DC Current Flow Controller (CFC) for meshed HVDC grids. It proposes a control design methodology based on an outer current loop to regulate DC grid currents and an inner voltage loop to keep under control the CFC voltage. This approach is able to limit the CFC voltage to avoid exceeding the device limitations. A linear model of the HVDC grid including the CFC is obtained to apply linear control techniques to design the regulator. The system performance is validated by means of simulations considering different case studies

Coordinated control design of the voltage and current loop of a current flow controller for meshed HVDC grids

This paper is focused in the control design of a DC/DC Current Flow Controller (CFC) for meshed HVDC grids. It proposes a control design methodology based on an outer current loop to regulate DC grid currents and an inner voltage loop to keep under control the CFC voltage. This approach is able to limit the CFC voltage to avoid exceeding the device limitations. A linear model of the HVDC grid including the CFC is obtained to apply linear control techniques to design the regulator. The system performance is validated by means of simulations considering different case studies.Postprint (published version