Aalborg, Denmark

University of Aalborg

Aalborg, Denmark

Aalborg University is a Danish university located mainly in Aalborg, Denmark with campuses in Aalborg, Esbjerg and Copenhagen. Aalborg University was established in 1974 under the name of Aalborg University Center , but changed its name to Aalborg University in 1994. Today, Aalborg University is the fifth largest university in Denmark based on the number of enrolled students. In Aalborg, the university is mainly located on the main campus in the eastern part of the city, but the university also has departments located in downtown Aalborg. Currently, Aalborg University has approximately 21,606 students and 3,479 employees. In 2011, Aalborg University experienced the largest increase in applicants in Denmark, as the number of new students increased by 31 per cent. Wikipedia.

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Dragicevic T.,University of Aalborg | Guerrero J.M.,University of Aalborg | Vasquez J.C.,University of Aalborg | Skrlec D.,University of Zagreb
IEEE Transactions on Power Electronics | Year: 2014

DC power systems are gaining an increasing interest in renewable energy applications because of the good matching with dc output type sources such as photovoltaic (PV) systems and secondary batteries. In this paper, several distributed generators (DGs) have been merged together with a pair of batteries and loads to form an autonomous dc microgrid (MG). To overcome the control challenge associated with coordination of multiple batteries within one stand-alone MG, a double-layer hierarchical control strategy was proposed. 1) The unit-level primary control layer was established by an adaptive voltage-droop method aimed to regulate the common bus voltage and to sustain the states of charge (SOCs) of batteries close to each other during moderate replenishment. The control of every unit was expanded with unit-specific algorithm, i.e., finish-of-charging for batteries and maximum power-point tracking (MPPT) for renewable energy sources, with which a smooth online overlap was designed and 2) the supervisory control layer was designed to use the low-bandwidth communication interface between the central controller and sources in order to collect data needed for adaptive calculation of virtual resistances (VRs) as well as transit criteria for changing unit-level operating modes. A small-signal stability for the whole range of VRs. The performance of developed control was assessed through experimental results. © 1986-2012 IEEE.

Document Keywords (matching the query): renewable energy source, distributed power generation, renewable energy applications, renewable energy resources, distributed generation dg, distributed generator dgs.

Guerrero J.,University of Barcelona | Blaabjerg F.,University of Aalborg | Zhelev T.,University of Limerick | Hemmes K.,Technical University of Delft | And 5 more authors.
IEEE Industrial Electronics Magazine | Year: 2010

Distributed generation (DG) is emerging as a new paradigm to produce on-site highly reliable and good quality electrical power. Thus, the DG systems are presented as a suitable form to offer highly reliable electrical power supply. The concept is particularly interesting when different kinds of energy resources are available, such as photovoltaic (PV) panels, fuel cells (FCs), or wind turbines. The DG of different kinds of energy systems allow for the integration of renewable and nonconventional energy resources. Hence, the DG is becoming a part of the strategic plans of most countries to address current challenges associated with energy management. © IEEE.

Document Keywords (matching the query): distributed generations, energy resources, distributed generation, energy management, energy systems, non conventional energy.

Sun K.,Tsinghua University | Zhang L.,Nanjing University of Aeronautics and Astronautics | Xing Y.,Nanjing University of Aeronautics and Astronautics | Guerrero J.M.,Polytechnic University of Catalonia | Guerrero J.M.,University of Aalborg
IEEE Transactions on Power Electronics | Year: 2011

Modular generation system, which consists of modular power conditioning converters, is an effective solution to integrate renewable energy sources with conventional utility grid to improve reliability and efficiency, especially for photovoltaic generation. A distributed control strategy based on improved dc bus signaling is proposed for a modular photovoltaic (PV) generation system with battery energy storage elements. In this paper, the modular PV generation system is composed of three modular dc/dc converters for PV arrays, two grid-connected dc/ac converters, and one dc/dc converter for battery charging/discharging and local loads, which is available of either grid-connected operation or islanding operation. By using the proposed control strategy, the operations of a modular PV generation system are categorized into four modes: islanding with battery discharging, grid-connected rectification, grid-connected inversion, and islanding with constant voltage (CV) generation. The power balance of the system under extreme conditions such as the islanding operation with a full-charged battery is taken into account in this control strategy. The dc bus voltage level is employed as an information carrier to distinguish different modes and determine mode switching. Control methods of modular dc/dc converters, battery converter, and grid-connected converter are addressed. An autonomous control method for modular dc/dc converters is proposed to realize smooth switching between CV operation and maximum power point tracking operation, which enables the dc bus voltage regulation capability of modular dc/dc converters. Seamless switching of a battery converter between charging and discharging and that of a grid-connected converter between rectification and inversion are ensured by the proposed control methods. Experiments verify the practical feasibility and the effectiveness of the proposed control strategies. © 2006 IEEE.

Document Keywords (matching the query): battery energy storage, distributed control, photovoltaic pv generation, distributed parameter control systems, photovoltaic generation, energy storage.

Camacho A.,Polytechnic University of Catalonia | Castilla M.,Polytechnic University of Catalonia | Miret J.,Polytechnic University of Catalonia | Vasquez J.C.,University of Aalborg | Alarcon-Gallo E.,Polytechnic University of Catalonia
IEEE Transactions on Industrial Electronics | Year: 2013

Ancillary services for distributed generation (DG) systems become a challenging issue to smartly integrate renewable-energy sources into the grid. Voltage control is one of these ancillary services which can ride through and support the voltage under grid faults. Grid codes from the transmission system operators describe the behavior of the energy source, regulating voltage limits and reactive power injection to remain connected and support the grid under fault. On the basis that different kinds of voltage sags require different voltage support strategies, a flexible control scheme for three-phase grid-connected inverters is proposed. In three-phase balanced voltage sags, the inverter should inject reactive power in order to raise the voltage in all phases. In one-or two-phase faults, the main concern of the DG inverter is to equalize voltages by reducing the negative symmetric sequence and clear the phase jump. Due to system limitations, a balance between these two extreme policies is mandatory. Thus, over-and undervoltage can be avoided, and the proposed control scheme prevents disconnection while achieving the desired voltage support service. The main contribution of this work is the introduction of a control algorithm for reference current generation that provides flexible voltage support under grid faults. Two different voltage sags have been experimentally tested to illustrate the behavior of the proposed voltage support control scheme. © 2012 IEEE.

Document Keywords (matching the query): reference current generation, distributed power generation, energy source, distributed generation system.

Rocabert J.,University of Barcelona | Luna A.,University of Barcelona | Blaabjerg F.,University of Aalborg | Rodriguez P.,Abengoa
IEEE Transactions on Power Electronics | Year: 2012

The enabling of ac microgrids in distribution networks allows delivering distributed power and providing grid support services during regular operation of the grid, as well as powering isolated islands in case of faults and contingencies, thus increasing the performance and reliability of the electrical system. The high penetration of distributed generators, linked to the grid through highly controllable power processors based on power electronics, together with the incorporation of electrical energy storage systems, communication technologies, and controllable loads, opens new horizons to the effective expansion of microgrid applications integrated into electrical power systems. This paper carries out an overview about microgrid structures and control techniques at different hierarchical levels. At the power converter level, a detailed analysis of the main operation modes and control structures for power converters belonging to microgrids is carried out, focusing mainly on grid-forming, grid-feeding, and grid-supporting configurations. This analysis is extended as well toward the hierarchical control scheme of microgrids, which, based on the primary, secondary, and tertiary control layer division, is devoted to minimize the operation cost, coordinating support services, meanwhile maximizing the reliability and the controllability of microgrids. Finally, the main grid services that microgrids can offer to the main network, as well as the future trends in the development of their operation and control for the next future, are presented and discussed. © 2012 IEEE.

Document Keywords (matching the query): energy resources, distributed power generation, distributed energy resources, distributed generation dg.

Liu X.,Nanyang Technological University | Loh P.C.,Nanyang Technological University | Wang P.,Nanyang Technological University | Blaabjerg F.,University of Aalborg | And 2 more authors.
IEEE Transactions on Power Electronics | Year: 2013

Indirect matrix converter (IMC) is an alternative for ac/ac energy conversion, usually operated with a voltage stepped-down gain of only 0.866. For applications like distribution generation where voltage-boost functionality is required, the traditional style of operating the IMC is therefore not appropriate. Like most power converters, the operation of the IMC can surely be reversed to produce a boosted gain, but so far its relevant control principles have not been discussed. These challenges are now addressed in this paper with distributed generation suggested as a potential application. Simulation and experimental results for validating various performance aspects of the proposed control schemes can be found in a later section of this paper. © 2012 IEEE.

Document Keywords (matching the query): energy conversion, distributed power generation, distribution generation.

Chen M.,University of Aalborg
IEEE Transactions on Instrumentation and Measurement | Year: 2014

To maximize the energy productivity, effective in-field detection and real-time control of defective thermoelectric modules (TEMs) are critical in constituting a thermoelectric generation system (TEGS). In this paper, autonomous and distributed sensor nodes are designed to implement the wireless TEM management in terms of the measurement criteria of defective TEMs formulated for series-parallel-connected TEM arrays and the control scheme based on the TEM-oriented switches. The instrumentation of a TEGS prototype and the design of the embedded software associated with the sensor nodes are described, respectively. Defective and potentially healing conditions are dynamically monitored by a voltage sensor node and a temperature sensor node, both of which can judge the defective TEM and decide the related switching actions in a nearly independent way. The periodical wireless transmission from the nodes to a base station is no longer necessary, and with the minimized amount of communication signals, the battery lifetime of the distributed nodes can be significantly prolonged. In the experimental tests, the autonomous sensor nodes successfully disconnect and reconnect the defective TEMs, where a considerable power improvement is illustrated with the proposed measuring method and setup. © 2013 IEEE.

Document Keywords (matching the query): thermoelectric energy conversion, distributed detection, thermoelectric generation systems, thermoelectric generation, energy productivity.

Levron Y.,Technion - Israel Institute of Technology | Guerrero J.M.,University of Aalborg | Beck Y.,Holon Institute of Technology
IEEE Transactions on Power Systems | Year: 2013

Energy storage may improve power management in microgrids that include renewable energy sources. The storage devices match energy generation to consumption, facilitating a smooth and robust energy balance within the microgrid. This paper addresses the optimal control of the microgrid's energy storage devices. Stored energy is controlled to balance power generation of renewable sources to optimize overall power consumption at the microgrid point of common coupling. Recent works emphasize constraints imposed by the storage device itself, such as limited capacity and internal losses. However, these works assume flat, highly simplified network models, which overlook the physical connectivity. This work proposes an optimal power flow solution that considers the entire system: the storage device limits, voltages limits, currents limits, and power limits. The power network may be arbitrarily complex, and the proposed solver obtains a globally optimal solution. © 1969-2012 IEEE.

Document Keywords (matching the query): renewable energy source, energy generations, distributed power generation, renewable energy resources, energy storage, distributed generation dg.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ICT-2013.6.1 | Award Amount: 4.75M | Year: 2014

SUNSEED proposes an evolutionary approach to utilisation of already present communication networks from both energy and telecom operators. These can be suitably connected to form a converged communication infrastructure for future smart energy grids offering open services. Life cycle of such communication network solutions consists of six steps: overlap, interconnect, interoperate, manage, plan and open. Joint communication networking operations steps start with analysis of regional overlap of energy and telecommunications operator infrastructures. Geographical overlap of energy and communications infrastructures identifies vital DSO energy and support grid locations (e.g. distributed energy generators, transformer substations, cabling, ducts) that are covered by both energy and telecom communication networks. Coverage can be realised with known wireline (e.g. copper, fiber)or wireless and mobile (e.g. WiFi, 4G) technologies. Interconnection assures end-2-end secure communication on the physical layer between energy and telecom, whereas interoperation provides network visibility and reach of smart grid nodes from both operator (utility) sides. Monitoring, control and management gathers measurement data from wide area of sensors and smart meters and assures stable distributed energy grid operation by using novel intelligent real time analytical knowledge discovery methods. For full utilisation of future network planning, we will integrate various public databases. Applications build on open standards (W3C) with exposed application programming interfaces (API) to 3rd parties enable creation of new businesses related to energy and communication sectors (e.g. virtual power plant operators, energy services providers for optimizing home energy use) or enable public wireless access points (e.g. WiFi nodes at distributed energy generator locations). SUNSEED life cycle steps promise much lower investments and total cost of ownership for future smart energy grids with dense distributed energy generation and prosumer involvement.

Agency: European Commission | Branch: H2020 | Program: IA | Phase: LCE-02-2016 | Award Amount: 11.23M | Year: 2016

The GOFLEX project will innovate, integrate, further develop and demonstrate a group of electricity smart-grid technologies, enabling the cost-effective use of demand response in distribution grids, increasing the grids available adaptation capacity and safely supporting an increasing share of renewable electricity generation. The GOFLEX smart grid solution will deliver flexibility that is both general (across different loads and devices) and operational (solving specific local grid problems). GOFLEX enables active use of distributed sources of load flexibility to provide services for grid operators, balance electricity demand and supply, and optimize energy consumption and production at the local level of electricity trading and distribution systems. Building on top of existing, validated technologies for capturing and exploiting distributed energy consumption and production flexibility, GOFLEX enables flexibility in automatic trading of general, localized, device-specific energy as well as flexibility in trading aggregated prosumer energy. Generalized demand-response services are based on transparent aggregation of distributed, heterogeneous resources to offer virtual-power-plant and virtual-storage capabilities. The sources of load flexibility include thermal (heating/cooling) and electric storage (electric vehicles charging/discharging). A backbone data-services platform offers localised estimation and short-term predictions of market and energy demand/generation, and flexibility in order to support effective data-driven decisions for the various stakeholders. Smart-grid technologies, such as increased observability and congestion management, contribute to the platform. Over 36 months, GOFLEX will demonstrate the benefits of the integrated GOFLEX solution in three use-cases, covering a diverse range of structural and operational distribution grid conditions in three European countries.

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