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Pegueroles-Queralt J.,Catalonia Institute for Energy Research IREC | Bianchi F.D.,Catalonia Institute for Energy Research IREC | Gomis-Bellmunt O.,Catalonia Institute for Energy Research IREC | Gomis-Bellmunt O.,Center dInnovacio Tecnologica en Convertidors Estatics i Accionaments
IEEE Transactions on Industrial Electronics | Year: 2015

With the increasing share of renewable power sources in distribution networks, a smooth delivery of the power generated has become a relevant requirement for ensuring proper power quality. This paper presents a simple power smoothing strategy based on supercapacitors for power conditioning of distributed renewable generation. The power smoothing controller generates the power reference for the dc/dc converter, which has a power tracking control implemented with sliding-mode techniques. The proposed strategy consists of a voltage controller capable of maintaining the optimal state of charge and reducing high-frequency components of the power coming from renewable energy sources. A generalization of the PI structure is used to ensure simple design and implementation. With the proposed control structure, tuning is reduced to find a state feedback gain based on a pole placement criterion. In addition, a criterion for selecting supercapacitors' size is provided. The effectiveness of the proposed power smoothing scheme is evaluated by simulations and validated in an experimental platform. © 1982-2012 IEEE. Source


Marzband M.,Catalonia Institute for Energy Research IREC | Sumper A.,Catalonia Institute for Energy Research IREC | Sumper A.,Polytechnic University of Catalonia | Sumper A.,Center dInnovacio Tecnologica en Convertidors Estatics i Accionaments | And 2 more authors.
Energy Conversion and Management | Year: 2013

Energy management systems (EMS) are vital supervisory control tools used to optimally operate and schedule Microgrids (MG). In this paper, an EMS algorithm based on mixed-integer nonlinear programming (MINLP) is presented for MG in islanding mode considering different scenarios. A local energy market (LEM) is also proposed with in this EMS to obtain the cheapest price, maximizing the utilization of distributed energy resources. The proposed energy management is based on LEM and allows scheduling the MG generation with minimum information shared sent by generation units. Load demand management is carried out by demand response concept to improve reliability and efficiency as well as to reduce the total cost of energy (COE). Simulations are performed with real data to test the performance and accuracy of the proposed algorithm. The proposed algorithm is experimentally tested to evaluate processing speed as well as to validate the results obtained from the simulation setup on a real MG Testbed. The results of the EMS-MINLP based on LEM are compared with a conventional EMS based on LEM. Simulation and experimental results show the effectiveness of the proposed algorithm which provides a reduction of 15% in COE, in comparison with conventional EMS. © 2013 Elsevier Ltd. All rights reserved. Source


Egea-Alvarez A.,Center dInnovacio Tecnologica en Convertidors Estatics i Accionaments | Beerten J.,Catholic University of Leuven | Van Hertem D.,Catholic University of Leuven | Gomis-Bellmunt O.,Center dInnovacio Tecnologica en Convertidors Estatics i Accionaments | Gomis-Bellmunt O.,Catalonia Institute for Energy Research IREC
Electric Power Systems Research | Year: 2015

This article introduces a hierarchical power control structure for Multi-terminal High Voltage Direct Current (MT-HVDC) systems. The presented hierarchy is similar to the control structure used in classical AC transmission systems and is divided in primary, secondary and tertiary control actions. The voltage control in the MT-HVDC scheme acts in a way similar to the primary control action of generators in AC systems, while the secondary control action is performed by an outer power control loop. The design of the individual controllers and the interaction between these control loops is discussed in detail. Furthermore, the operational characteristics are described and the main operating points are identified. Scenarios including a power reference change and a grid side converter disconnection have been simulated in order to test and verify the proposed method. The main contribution of the paper is the development of a control methodology, providing a separation of the different control actions in different time domains, similar to what is already in use (and therefore known) within traditional power systems. © 2014 Elsevier B.V. All rights reserved. Source


Diaz-Gonzalez F.,Catalonia Institute for Energy Research IREC | Hau M.,Fraunhofer Institute for Wind Energy and Energy System Technology | Sumper A.,Catalonia Institute for Energy Research IREC | Sumper A.,Center dInnovacio Tecnologica en Convertidors Estatics i Accionaments | And 2 more authors.
International Journal of Electrical Power and Energy Systems | Year: 2015

This work assesses the participation of wind power plants in primary frequency control support. To participate in frequency control-related tasks, the wind power plants have to maintain a certain level of power reserves. In this article, the wind power plant is equipped with a flywheel-based storage system to fulfil the power reserve requirements set by the network operator. The article focuses on two main aspects: the definition of the control strategy to derate the wind turbines to provide a part of the required power reserves; and the coordinated regulation of the power reserves of the wind turbines and the flywheels while participating in primary frequency control. This coordinated regulation enables the wind power plant to maintain the net level of power reserves set by the network operator while alleviating the need of deloading the wind turbines. The performance of the proposed control schemes are shown by simulation. © 2015 Elsevier Ltd. All rights reserved. Source


Aragues-Penalba M.,Center dInnovacio Tecnologica en Convertidors Estatics i Accionaments | Egea-Alvarez A.,Center dInnovacio Tecnologica en Convertidors Estatics i Accionaments | Arellano S.G.,Center dInnovacio Tecnologica en Convertidors Estatics i Accionaments | Gomis-Bellmunt O.,Center dInnovacio Tecnologica en Convertidors Estatics i Accionaments | Gomis-Bellmunt O.,Catalonia Institute for Energy Research IREC
Electric Power Systems Research | Year: 2014

A control scheme is proposed in order to minimize the losses in multi-terminal HVDC systems for large offshore wind power plants. This approach is based on two cascaded control schemes. A low level droop control regulates appropriately the DC current depending on the DC voltage with the purpose of ensuring a stable voltage in DC system. Another higher hierarchy controller guarantees that power flow is optimal. The proposed scheme enables to perform secondary and tertiary control strategies into the DC grid taking profit of the advantages of each individual control scheme: the robustness of droop control and the minimisation of losses ensured by the optimal power flow (OPF) algorithm. Total losses include transmission losses and converter station losses. A steady state analysis is provided to show the power flows that minimise several objective functions and dynamic simulations are performed to illustrate the dynamic behaviour of the control scheme under wind speed changes and communication faults. © 2014 Elsevier B.V. Source

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