Navegando por Assunto "Distributed generation (DG)"

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Acesso aberto (Open Access)
Estudos de geradores distribuídos de grande porte conectados ao sistema elétrico via conversores cc-ca aplicados ao projeto de estabilizadores de sistemas de potência
(Universidade Federal do Pará, 2015-12-16) FONSECA, Maria da Conceição Pereira; BARRA JUNIOR, Walter; http://lattes.cnpq.br/0492699174212608
This thesis presents a study to develop linear models suitable for conducting stability studies in interconnected electrical power systems that include large utility-scale inverterconnected power stations. To that end, an extended Heffron-Phillips-type model was developed for a study power system consisting of a utility-scale inverter-connected power source and a synchronous generator, both of which having similar power ratings and being interconnected to a larger power system (infinite bus bar). Due to the presence of the distributed generator and associated current regulating control subsystem, the extended model presents a set of signal channels originating at the current regulation subsystem of the distributed generator and arriving at the torque summing point of the synchronous generator. By performing a large set of computational tests, for a wide range of operating conditions, the relative importance of these new channel gains were assessed. It was found that the gains associated with the direct paths have a predominant influence on the contribution of the distributed generator for both synchronizing as well as damping torques actuating on the synchronous generator shaft. Furthermore, the values of these path gains prove to be negligible when the generation level of the distributed generator is rather reduced. This observation allowed for performing further model simplifications in order to obtain a more suitable model for Power System Stabilizers (PSS) design for such class of power systems. In addition, new formulae are proposed hereby which allow for estimating the values of the synchronizing and damping torque coefficients as a function of the active power generation level of the distributed generator. For the test power system, a PSS damping controller was designed by using the developed simplified model. Subsequent ly, the PSS performance degradation has been investigated for a large set of operating conditions, The results showed considerable PSS performance detuning for those operating conditions corresponding to increased generating level at the distributed generator in comparison to synchronous active power generating level. Supplementary computational tests were performed to evaluate potential adverse interacting effects between the PSS and the proportional and integral (PI) control of a TCSC FACTS device in the area. It was found that moderate values must be chosen in order not to substantially reduce the system stability.
Acesso aberto (Open Access)
Inibidor bidirecional de eventos de runaway no comutador de tap de reguladores de tensão em redes de distribuição reconfiguráveis com geração distribuída
(Universidade Federal do Pará, 2024-06-25) SOUZA, Vanderson Carvalho de; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
Climate change has intensified over the years, especially as a result of the global energy model that is predominantly based on the use of fossil fuels. Thus, there is an urgent need to boost a low-carbon economy as a response to the climate crisis. In this context, renewable energy sources emerge as the main alternative to fossil fuels. However, the integration of these sources into distribution networks can cause voltage control problems resulting from bidirectional power flow in such networks. An important voltage control problem is the phenomenon known as tap changer runaway condition in step-voltage regulators (SVRs). Nowadays, the problem is further challenging in reconfigurable distribution networks with renewable energy sources connected to both the source-side and load-side of the SVR. This problem occurs when the SVR control cannot adequately distinguish the origin of the active power flow through the SVR and tries to control the voltage on the side of the network with the highest short circuit capacity (strong side), causing under or overvoltage on the side of the network with the lowest short circuit capacity. short circuit (weak side). Current solutions to mitigate the runaway problem are mainly based on three categories: 1) voltage control support by distributed generation (DG); 2) use of remote measurements/information; and 3) use of local measurements/information. However, considering practical aspects, only solutions in the third category are feasible. Even so, these solutions are restricted to application for inhibiting the runaway condition caused exclusively by reverse power flow. In this Thesis, an algorithm is proposed for robust local bidirectional on-line inhibition of the runaway condition based only on a test tap switching with robustness guarantees and without the need for switching of tap test coordinate in cascaded SVRs. The main contributions of the Thesis are the innovative application of the algorithm in robust local bidirectional on-line inhibition of the runaway condition in the tap switch and the introduction to industrial insights. The accuracy and robustness of the proposed algorithm are verified through time series power flow simulations carried out on two test networks, with noise and gross errors in measurements, using extensive Monte Carlo simulations. The uncoordinated operation of test tap switching in cascaded SVRs is examined through case studies on a long real rural distribution network. Finally, the effect of photovoltaic (PV) source variability on the performance of the proposed algorithm is evaluated. The results obtained confirmed the effectiveness of the proposed algorithm in bidirectional inhibition of the runaway condition
Acesso aberto (Open Access)
Metodologia de planejamento para inserção de geradores fotovoltaicos em redes elétricas isoladas e supridas por geradores a diesel
(Universidade Federal do Pará, 2013-09-05) GONÇALVES, Cláudio; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
Renewable energy sources based on photovoltaic generation (PVG) are promising energy alternatives to complement conventional, centralized power generation, as the diesel thermal plants supplying power to isolated grids in cities and remote locations in the Amazon Region. The allocation and sizing of generators for distributed generation application (DG) is a challenging problem, with technical and economic implications related to the planning, design and operation of these systems. Particularly, the PVG presents added difficulty as it is a function of environmental conditions, mainly temperature and solar radiation. This thesis presents an analytical methodology to allocate and size active power photovoltaic generation units with embedded DC/AC inverter (PVGI) to be integrated as concentrated or dispersed generation in isolated medium voltage electrical grids. The proposed methodology considers multiple objectives to be reached namely: improving the electrical grid voltage profile; reducing active power losses; and reducing the diesel generation participation, providing, this way, a reduction in diesel oil consumption and in the environmental pollution. The global obtained solution of the proposed method is a weighted commitment to these goals, presenting different weights according to priorities established in the electrical system under planning. To validate the proposed methodology, the IEEE 33 and 69 buses networks and an isolated real electrical system were modeled and simulated. The real electrical system is located in Aveiro City, in the Amazon region, Brazil. The simulation results obtained demonstrated that the proposed methodology is effective in providing a solution with significant improvement in voltage profile, active power losses reduction, and diesel generation participation reduction, according to viable technical and economic indicators to the PVGI integration in the isolated electrical grid.