231 resultados para grid integration


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Following several political-psychological approaches, the present research analyzed whether orientations toward human rights are a function of right-wing authoritarianism (RWA), social dominance orientation (SDO), basic human values in the sense of Schwartz (1992), and political ideology. Three dimensions of human rights attitudes (endorsement, restriction, and enforcement) were differentiated from human rights knowledge and behavior. In a time-lagged Internet survey (N = 479), using structural equation modeling, RWA, universalism and power values, and political ideology (measured at Time 1) differentially predicted dimensions of human rights attitudes (measured at Time 2 five months later). RWA and universalism values also predicted self-reported human rights behavior, with the effects mediated through human rights endorsement. Human rights knowledge also predicted behavior. The psychological roots of positive and negative orientations toward human rights, consequences for human rights education, and the particular role of military enforcement of human rights are discussed.

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The Irish border has historically been one of the most contested borders in Europe. In the context of the peace process and EU membership, co-operation between Northern Ireland and the Republic of Ireland has been encouraged, supported and normalised, although internal borders of segregation stubbornly remain. This paper offers a conceptualisation of borders in conflict cases and a theoretical account of how European integration can affect their transformation. Analysis of the Northern Ireland case shows there are ambiguities within integration that allow for a ‘rebordering’ of identities at the same time as the state border diminishes in significance.

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A graphical method is presented for determining the capability of individual system nodes to accommodate wind power generation. The method is based upon constructing a capability chart for each node at which a wind farm is to be connected. The capability chart defines the domain of allowable power injections at the candidate node, subject to constraints imposed by voltage limits, voltage stability and equipment capability limits being satisfied. The chart is first derived for a two-bus model, before being extended to a multi-node power system. The graphical method is employed to derive the chart for a two-node system, as well as its application to a multi-node power system, considering the IEEE 30-bus test system as a case study. Although the proposed method is derived with the intention of determining the wind farm capacity to be connected at a specific node, it can be used for the analysis of a PQ bus loading as well as generation.

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Conditionality is formally a key determinant of many non-member states’ relations with the EU. It is particularly so for states intent on membership. As the case of Romania shows, the EU’s use of conditionality is far from consistent. Relations can develop and accession take place without the requisite conditions being met. This follows from the use the EU makes of the flexibility evident in its evolving and generally vague definitions of the conditions that need to be met. Hence it was often extraneous factors over which Romania had either limited or no influence that were responsible for key developments in relations. These factors include the geopolitical and strategic interests of the EU and its member states, the actions of the Commission and the agenda-setting and constraining effects of rhetorical commitments and timetables, and the dynamics of the EU’s evolving approach to eastern enlargement.

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Peptidomics is a powerful set of tools for the identification, structural elucidation and discovery of novel regulatory peptides and for monitoring the degradation pathways of structurally and catalytically important proteins. Amphibian skin secretions, arising from specialized granular glands, often contain complex peptidomes containing many components of entirely novel structure and unique site-substituted analogues of known peptide families. Following the discovery that the granular gland transcriptome is present in such secretions in a PCR-amenable form, we designed a strategy for peptide structural characterization involving the integration of ‘shotgun’ cloning of cDNAs encoding peptide precursors, deduction of putative bioactive peptide structures, and confirmation of these structures using tandem MS/MS sequencing. Here, we illustrate this strategy by means of elucidation of the primary structures of nigrocin-2 homologues from the defensive skin secretions of four species of Chinese Odorrana frogs, O. schmackeri, O. livida, O. hejiangensis and O. versabilis. Synthetic replicates of the peptides were found to possess antimicrobial activity. Nigrocin-2 peptides occur widely in the skin secretions of Asian ranid frogs and in those of the Odorrana group, and are particularly well-represented and of diverse structure in some species. Integration of the molecular analytical technologies described provides a means for rapid structural characterization of novel peptides from complex natural libraries in the absence of systematic online database information.

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This paper proposes a coordinated control of the rotor and grid side converters (RSC & GSC) of doubly-fed induction generator (DFIG) based wind generation systems under unbalanced voltage conditions. System behaviors and operations of the RSC and GSC under unbalanced voltage are illustrated. To provide enhanced operation, the RSC is controlled to eliminate the torque oscillations at double supply frequency under unbalanced stator supply. The oscillation of the stator output active power is then cancelled by the active power output from the GSC, to ensure constant active power output from the overall DFIG generation system. To provide the required positive and negative sequence currents control for the RSC and GSC, a current control strategy containing a main controller and an auxiliary controller is analyzed. The main controller is implemented in the positive (dq)+ frame without involving positive/negative sequence decomposition whereas the auxiliary controller is implemented in the negative sequence (dq)? frame with negative sequence current extracted. Simulation results using EMTDC/PSCAD are presented for a 2MW DFIG wind generation system to validate the proposed control scheme and to show the enhanced system operation during unbalanced voltage supply.

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This paper investigates the control and operation of doubly-fed induction generator (DFIG) and fixed-speed induction generator (FSIG) based wind farms under unbalanced grid conditions. A DFIG system model suitable for analyzing unbalanced operation is developed, and used to assess the impact of an unbalanced supply on DFIG and FSIG operation. Unbalanced voltage at DFIG and FSIG terminals can cause unequal heating on the stator windings, extra mechanical stresses and output power fluctuations. These problems are particularly serious for the FSIG-based wind farm without a power electronic interface to the grid. To improve the stability of a wind energy system containing both DFIG and FSIG based wind farms during network unbalance, a control strategy of unbalanced voltage compensation by the DFIG systems is proposed. The DFIG system compensation ability and the impact of transmission network impedance are illustrated. The simulation results implemented in Matlab/Simulink show that the proposed DFIG control system improves not only its own performance, but also the stability of the FSIG system with the same grid connection point during network unbalance.