3,495 research outputs found
Nonlinear Control of a DC MicroGrid for the Integration of Photovoltaic Panels
New connection constraints for the power network (Grid Codes) require more
flexible and reliable systems, with robust solutions to cope with uncertainties
and intermittence from renewable energy sources (renewables), such as
photovoltaic arrays. The interconnection of such renewables with storage
systems through a Direct Current (DC) MicroGrid can fulfill these requirements.
A "Plug and Play" approach based on the "System of Systems" philosophy using
distributed control methodologies is developed in the present work. This
approach allows to interconnect a number of elements to a DC MicroGrid as power
sources like photovoltaic arrays, storage systems in different time scales like
batteries and supercapacitors, and loads like electric vehicles and the main AC
grid. The proposed scheme can easily be scalable to a much larger number of
elements.Comment: arXiv admin note: text overlap with arXiv:1607.0848
Nonlinear Control of an AC-connected DC MicroGrid
New connection constraints for the power network (Grid Codes) require more
flexible and reliable systems, with robust solutions to cope with uncertainties
and intermittence from renewable energy sources (renewables), such as
photovoltaic arrays. A solution for interconnecting such renewables to the main
grid is to use storage systems and a Direct Current (DC) MicroGrid. A "Plug and
Play" approach based on the "System of Systems" philosophy using distributed
control methodologies is developed in the present work. This approach allows to
interconnect a number of elements to a DC MicroGrid as power sources like
photovoltaic arrays, storage systems in different time scales like batteries
and supercapacitors, and loads like electric vehicles and the main AC grid. The
proposed scheme can easily be scalable to a much larger number of elements.Comment: IEEE IECON 2016, the 42nd Annual Conference of IEEE Industrial
Electronics Society, October 24-27, 201
European White Book on Real-Time Power Hardware in the Loop Testing : DERlab Report No. R- 005.0
The European White Book on Real-Time-Powerhardware-in-the-Loop testing is intended to serve as a reference document on the future of testing of electrical power equipment, with speciïŹ c focus on the emerging hardware-in-the-loop activities and application thereof within testing facilities and procedures. It will provide an outlook of how this powerful tool can be utilised to support the development, testing and validation of speciïŹ cally DER equipment. It aims to report on international experience gained thus far and provides case studies on developments and speciïŹ c technical issues, such as the hardware/software interface. This white book compliments the already existing series of DERlab European white books, covering topics such as grid-inverters and grid-connected storag
Control of AC/DC microgrids with renewables in the context of smart grids including ancillary services and electric mobility
Microgrids are a very good solution for current problems raised by the constant growth
of load demand and high penetration of renewable energy sources, that results in grid
modernization through âSmart-Gridsâ concept. The impact of distributed energy sources
based on power electronics is an important concern for power systems, where natural
frequency regulation for the system is hindered because of inertia reduction. In this context,
Direct Current (DC) grids are considered a relevant solution, since the DC nature of power
electronic devices bring technological and economical advantages compared to Alternative
Current (AC). The thesis proposes the design and control of a hybrid AC/DC Microgrid
to integrate different renewable sources, including solar power and braking energy recovery
from trains, to energy storage systems as batteries and supercapacitors and to loads like
electric vehicles or another grids (either AC or DC), for reliable operation and stability.
The stabilization of the Microgrid busesâ voltages and the provision of ancillary services
is assured by the proposed control strategy, where a rigorous stability study is made.
A low-level distributed nonlinear controller, based on âSystem-of-Systemsâ approach is
developed for proper operation of the whole Microgrid. A supercapacitor is applied to
deal with transients, balancing the DC bus of the Microgrid and absorbing the energy
injected by intermittent and possibly strong energy sources as energy recovery from the
braking of trains and subways, while the battery realizes the power flow in long term.
Dynamical feedback control based on singular perturbation analysis is developed for
supercapacitor and train. A Lyapunov function is built considering the interconnected
devices of the Microgrid to ensure the stability of the whole system. Simulations highlight
the performance of the proposed control with parametric robustness tests and a comparison
with traditional linear controller. The Virtual Synchronous Machine (VSM) approach is
implemented in the Microgrid for power sharing and frequency stability improvement. An
adaptive virtual inertia is proposed, then the inertia constant becomes a systemâs state
variable that can be designed to improve frequency stability and inertial support, where
stability analysis is carried out. Therefore, the VSM is the link between DC and AC side
of the Microgrid, regarding the available power in DC grid, applied for ancillary services
in the AC Microgrid. Simulation results show the effectiveness of the proposed adaptive
inertia, where a comparison with droop and standard control techniques is conducted.As Microrredes são uma ótima solução para os problemas atuais gerados pelo constante crescimento
da demanda de carga e alta penetração de fontes de energia renovåveis, que resulta na modernização
da rede atravĂ©s do conceito âSmart-Gridsâ. O impacto das fontes de energia distribuĂdas baseados
em eletrĂŽnica de potĂȘncia Ă© uma preocupação importante para o sistemas de potĂȘncia, onde a
regulação natural da frequĂȘncia do sistema Ă© prejudicada devido Ă redução da inĂ©rcia. Nesse
contexto, as redes de corrente contĂnua (CC) sĂŁo consideradas um progresso, jĂĄ que a natureza
CC dos dispositivos eletrÎnicos traz vantagens tecnológicas e econÎmicas em comparação com a
corrente alternada (CA). A tese propĂ”e o controle de uma Microrrede hĂbrida CA/CC para integrar
diferentes fontes renovåveis, incluindo geração solar e frenagem regenerativa de trens, sistemas de
armazenamento de energia como baterias e supercapacitores e cargas como veĂculos elĂ©tricos ou
outras (CA ou CC) para confiabilidade da operação e estabilidade. A regulação das tensÔes dos
barramentos da Microrrede e a prestação de serviços anciliares são garantidas pela estratégia
de controle proposta, onde Ă© realizado um rigoroso estudo de estabilidade. Um controlador nĂŁo
linear distribuĂdo de baixo nĂvel, baseado na abordagem âSystem-of-Systemsâ, Ă© desenvolvido para
a operação adequada de toda a rede elétrica. Um supercapacitor é aplicado para lidar com os
transitĂłrios, equilibrando o barramento CC da Microrrede, absorvendo a energia injetada por fontes
de energia intermitentes e possivelmente fortes como recuperação de energia da frenagem de trens
e metrĂŽs, enquanto a bateria realiza o fluxo de potĂȘncia a longo prazo. O controle por dynamical
feedback baseado numa anĂĄlise de singular perturbation Ă© desenvolvido para o supercapacitor e
o trem. FunçÔes de Lyapunov sĂŁo construĂdas considerando os dispositivos interconectados da
Microrrede para garantir a estabilidade de todo o sistema. As simulaçÔes destacam o desempenho
do controle proposto com testes de robustez paramétricos e uma comparação com o controlador
linear tradicional. O esquema de mĂĄquina sĂncrona virtual (VSM) Ă© implementado na Microrrede
para compartilhamento de potĂȘncia e melhoria da estabilidade de frequĂȘncia. EntĂŁo Ă© proposto o
uso de inércia virtual adaptativa, no qual a constante de inércia se torna variåvel de estado do
sistema, projetada para melhorar a estabilidade da frequĂȘncia e prover suporte inercial. Portanto,
o VSM realiza a conexĂŁo entre lado CC e CA da Microrrede, onde a energia disponĂvel na rede CC
é usada para prestar serviços anciliares no lado CA da Microrrede. Os resultados da simulação
mostram a eficåcia da inércia adaptativa proposta, sendo realizada uma comparação entre o
controle droop e outras técnicas de controle convencionais
Neuro-Fuzzy Based High-Voltage DC Model to Optimize Frequency Stability of an Offshore Wind Farm
Lack of synchronization between high voltage DC systems linking offshore wind farms and the onshore grid is a natural consequence owing to the stochastic nature of wind energy. The poor synchronization results in increased system disturbances, grid contingencies, power loss, and frequency instability. Emphasizing frequency stability analysis, this research investigates a dynamic coordination control technique for a Double Fed Induction Generator (DFIG) consisting of OWFs integrated with a hybrid multi-terminal HVDC (MTDC) system. Line commutated converters (LCC) and voltage source converters (VSC) are used in the suggested control method in order to ensure frequency stability. The adaptive neuro-fuzzy inference approach is used to accurately predict wind speed in order to further improve frequency stability. The proposed HVDC system can integrate multiple distributed OWFs with the onshore grid system, and the control strategy is designed based on this concept. In order to ensure the transient stability of the HVDC system, the DFIG-based OWF is regulated by a rotor side controller (RSC) and a grid side controller (GSC) at the grid side using a STATCOM. The devised HVDC (MTDC) is simulated in MATLAB/SIMULINK, and the performance is evaluated in terms of different parameters, such as frequency, wind power, rotor and stator side current, torque, speed, and power. Experimental results are compared to a conventional optimal power flow (OPF) model to validate the performance.© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed
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An Assessment of PIER Electric Grid Research 2003-2014 White Paper
This white paper describes the circumstances in California around the turn of the 21st century that led the California Energy Commission (CEC) to direct additional Public Interest Energy Research funds to address critical electric grid issues, especially those arising from integrating high penetrations of variable renewable generation with the electric grid. It contains an assessment of the beneficial science and technology advances of the resultant portfolio of electric grid research projects administered under the direction of the CEC by a competitively selected contractor, the University of Californiaâs California Institute for Energy and the Environment, from 2003-2014
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