2013
Autores
Gouveia, C; Moreira, CL; Pecas Lopes, JAP;
Publicação
2013 IEEE GRENOBLE POWERTECH (POWERTECH)
Abstract
Within the Smart Grid paradigm, the MicroGrid concept (MG) presents an adequate framework to monitor and manage the low voltage network and coordinate the resources connected to it, including the smart grid new players, namely the consumers, prosumers and the Electric Vehicles (EV). The coordinated management and control of the MG resources, enables the operation both connected to the main power network or autonomously, due to planned or unplanned outages. In order to operate autonomously, the MG relies in its storage capacity to provide some form of energy buffering capabilities to balance load and generation. This paper presents innovative methodology to coordinate the microgrid storage capacity with EV smart charging strategies and demand response schemes, in order to improve microgrid resilience in the moments subsequent to islanding and reduce the non-served load. The effectiveness of the proposed algorithms are validated though extensive numerical simulations.
2017
Autores
Filipe, J; Bessa, R; Moreira, C; Silva, B;
Publicação
HYPERBOLE SYMPOSIUM 2017 (HYDROPOWER PLANTS PERFORMANCE AND FLEXIBLE OPERATION TOWARDS LEAN INTEGRATION OF NEW RENEWABLE ENERGIES)
Abstract
The increase penetration of renewable energy sources (RES) into the European power system has introduced a significant amount of variability and uncertainty in the generation profiles raising the needs for ancillary services as well as other tools like demand response, improved generation forecasting techniques and changes to the market design. While RES is able to replace energy produced by the traditional centralized generation, it cannot displace its capacity in terms of ancillary services provided. Therefore, centralized generation capacity must be retained to perform this function leading to over-capacity issues and underutilisation of the assets. Large-scale reversible hydro power plants represent the majority of the storage solution installed in the power system. This technology comes with high investments costs, hence the constant search for methods to increase and diversify the sources of revenue. Traditional fixed speed pump storage units typically operate in the day-ahead market to perform price arbitrage and, in some specific cases, provide downward replacement reserve (RR). Variable speed pump storage can not only participate in RR but also contribute to FRR, given their ability to control its operating point in pumping mode. This work does an extended analysis of a complete bidding strategy for Pumped Storage Power, enhancing the economic advantages of variable speed pump units in comparison with fixed ones.
2013
Autores
Silva, B; Moreira, CL; Leite, H;
Publicação
2013 IEEE PES CONFERENCE ON INNOVATIVE SMART GRID TECHNOLOGIES (ISGT LATIN AMERICA)
Abstract
A fully operational Multi-Terminal DC (MTDC) grid will play a key role for the creation of AC systems interconnection and to integrate offshore wind farms. Disturbances (at both AC and DC side) may culminate in the sudden disconnection of onshore HVDC-VSC (High Voltage Direct Current - Voltage Source Converter). To continue operating the DC grid under these conditions, the development of control functionalities is required. A communication-free advanced control scheme is proposed to be used as a supplementary local control acting at VSC level and aiming on providing fast active power accommodation in the DC grid, culminating on the mitigation of the resulting DC overvoltage. The implementation of the proposed control mechanisms exploits a set of coordinated local control rules at the converter stations and at wind turbines (WT) level. The performance of the proposed strategies is discussed and assessed through numerical simulation in the paper.
2014
Autores
Moreira, CL; Silva, B;
Publicação
2014 IEEE INTERNATIONAL ENERGY CONFERENCE (ENERGYCON 2014)
Abstract
A fully operational Multi-Terminal DC (MTDC) grid will play a strategic role for mainland AC systems interconnection and to integrate offshore wind farms. The importance of such infrastructure requires its compliance with Fault Ride Through (FRT) capability in case of mainland AC faults. In order to provide FRT capability in MTDC grids, communication-free advanced control functionalities exploiting a set of local control rules at the converter stations and wind turbines are identified. The proposed control functionalities are responsible for mitigating the DC voltage rise effect resulting from the reduction of active power injection into onshore AC systems during grid faults. The proposed strategies envision a fast control of the wind turbine active power output as a function of the DC grid voltage rise and constitute alternative options in order to avoid the use of classical solutions based on the installation of chopper resistors in the MTDC grid. The feasibility and robustness of the proposed strategies are demonstrated and discussed in the paper while considering different circumstances.
2013
Autores
Miranda, LM; Varajao, D; Dos Santos, B; Araujo, RE; Moreira, CL; Lopes, JAP;
Publicação
2013 15th European Conference on Power Electronics and Applications, EPE 2013
Abstract
This paper describes a power conversion system that implements bidirectional power flow between the electric grid and a battery, based on a full bridge inverter associated with a dual active bridge. A method for power flow control based on the agreement between battery pack and low voltage grid requirements has been developed to allow the large penetration of both, electric vehicles (EV) and renewable microgeneration. A laboratory prototype containing all functions required to implement a vehicle-to-grid (V2G) power interface has been built. The hardware implementation is reported, including control scheme and high-frequency transformer design details. Converter key waveforms are presented to evaluate the power quality on batteries and grid, as well as its dynamic behavior. An experimental laboratory setup is described and results are shown to demonstrate the technical benefits for low-voltage (LV) microgrids, if electric vehicle charger includes a power flow control based on frequency-voltage droop concept. © 2013 IEEE.
2013
Autores
Seca, L; Costa, H; Moreira, CL; Lopes, JAP;
Publicação
Proceedings of IREP Symposium: Bulk Power System Dynamics and Control - IX Optimization, Security and Control of the Emerging Power Grid, IREP 2013
Abstract
This paper presents an innovative Power System Restoration (PSR) that exploits the flexibility offered by large offshore wind parks, in particular with HVDC connection with Voltage Source converter (VSC) technology, to support restoration following a black out in a typical transmission grid. Restoration sequences comparing different strategies in a VHV AC network with conventional generation (thermal units and hydro units) were implemented for two cases: with and without the participation of a large offshore wind farm in the restoration plan. In order to evaluate the benefit of using Utility scale Wind Parks to support PSR, a typical transmission network with all its models (including HVDC link with DC converter) was implemented in EUROSTAG simulation platform. © 2013 IEEE.
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