Navegando por Assunto "Estabilidade de tensão"

Agora exibindo 1 - 4 de 4

Acesso aberto (Open Access)
Análise da área de vulnerabilidade e estabilidade de tensão em sistemas elétricos com a inserção de parques eólicos
(Universidade Federal do Pará, 2005-09-30) MATOS, Kayt Nazaré do Vale; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447
The present dissertation evaluates the voltage sag and stability of the real electrical system with the insertion of wind farms. The voltage sags studies serve of base for determination of the vulnerability areas of the electrical system, in which, in turn, the aspects are investigated regarding the voltage instability caused by the integration of wind systems with asynchronous generators. For that, the computational program ANAQUALI developed by CEPEL (Centro de Pesquisas de Energia El?trica) was used. In the study of the voltage dynamic behavior due to short circuit, in which the wind system is inserted in the conceptions of fixed speed and variable speed, a computational program developed in the MATLABTM software is used. The results of these simulations evidence that variable speed wind system provides a larger voltage stability edge to the electrical system, due to presence of the speed and voltage control. These studies commonly are not applied to the distributed generation system, and therefore, this dissertation also contributes in this aspect, and the results can serve of base for the planning of wind parks inserted in conventional electrical systems.
Acesso aberto (Open Access)
Análise estática e dinâmica de parques eólicos mistos compostos por aerogeradores de velocidade fixa e variável
(Universidade Federal do Pará, 2014-11-21) SILVA, Helleson Jorthan Brito da; AFFONSO, Carolina de Mattos; http://lattes.cnpq.br/2228901515752720
The wind electric power generation systems are presented as an appropriate solution to meet the technical, economic, environmental, social and governmental requirements, therefore they have been largely used in several countries. Among the wind turbines technologies available, the speed-fixed with squirrel cage induction generator and variable-speed with doubly fed induction generator wind systems are the most popular. With increasing of the wind penetration levels in electrical grid and due the technologic drawbacks of the wind turbine with cage induction generator, a tend to replace this concept by wind turbine with doubly fed induction generator in the construction of new wind farms is seen. In the case of wind plant installed already, for economic reasons, the gradative modernization process is more convenient. Although both wind systems are well known, but about the combined operation of them is known a little. Thus, the present paper proposes a study to evaluate the impacts occurred by integration of a mixed wind farm in the electrical grid, with squirrel cage and doubly fed induction generators. Aspects related to transient stability under fault and short wind variations and voltage stability are analyzed. The interactions between the technologies are also object of study. Cases with different penetration levels of the wind systems are considered, representing the gradative replace of part of the old concept wind turbine by others of the concept more modern. The results obtained show that the characteristics of the doubly fed induction generator allied with the reduction of the power injection of the fixed-speed wind systems improve the wind farm behavior, suggesting that the combined operation of the wind turbines could be a more costeffective solution.
Acesso aberto (Open Access)
Avaliação da margem de estabilidade de tensão do sistema elétrico do tramoeste usando dados reais de sincrofasores de tensão e corrente
(Universidade Federal do Pará, 2013-03-06) BERNARDES, Bernard Carvalho; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
The present work evaluates the voltage stability margin at the Rurópolis 230-kV substation on the Tramoeste Eletrobrás Eletronorte Power System using local voltage and current phasor measurements obtained from the Eletronorte’s phasor data concentrator (PDC). The evaluation is based on the identification of the Thevenin voltage and impedance equivalents “seen” from the bus under analysis. The Thevenin equivalent parameters are estimated through the local voltage and current phasor measurements. It is also possible to compute the equivalent load impedance using the same phasor measurements. The voltage stability margin determines the distance between the absolute values of the Thevenin equivalent impedance and the load impedance. The proposed analysis was tested in the Ruropolis 230 kV load bus, in three different operational situations: 1) light and heavy loads at Ruropolis bus 2) minimum and maximum generation levels at the Tucuruí hydroelectric power plant 3) two large perturbations that occurred on the Brazilian Interconnected Power System. The obtained results demonstrated a promising application of the proposed analysis for use in real time power system voltage security monitoring benefiting the applications of remedial actions.
Acesso aberto (Open Access)
Impacto de redes de distribuição com massiva conexão de geradores fotovoltaicos na estabilidade de tensão de longo-prazo em sistemas de potência
(Universidade Federal do Pará, 2017-03-31) BARATA, Heitor Alves; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
This dissertation aims to show the impact of distributed photovoltaic generators connected to distribution networks on long term voltage stability using full time simulation. The effect of different penetration levels of photovoltaic generation is investigated. Different distribution network models considering distributed generation (DG) connections is also investigated: 1) Load and DG represented by ZIP model and negative active power loads, respectively, connected to the substation bus; 2) Load and DG represented by ZIP model and dynamic equivalent, respectively, connected to the substation bus; 3) Load and GD represented by ZIP model and dynamic model, respectively, distributed along a MV distribution network. Equipments such as On-Load Tap Changer (OLTC) transformers, Overexcitation Limiter (OEL), static loads and step voltage regulators are taken into account in the analyzes, since they significantly affect the long-term voltage stability. The investigations were conducted using both the power flow software ANAREDE and transient stability simulator ANATEM, developed by the Electrical Energy Research Center (CEPEL). For the purpose of power flow studies, photovoltaic generators are modeled as PQ buses with Q=0. The modelling of photovoltaic generators for dynamic studies is based on WECC (Western Electricity Coordinating Council) model, wich was inserted into file User Defined Controller (CDU) from ANATEM. The undervoltage protection of photovoltaic generator is also considered. The case studies were performed on a combined transmission and distribution model.