Sérgio Faias

Evaluation of energy storage devices for renewable energies integration: Application to a Portuguese wind farm

This paper evaluates the benefits of energy storage systems applied to renewable intermittent sources like wind. With this objective, a 144 MW Portuguese wind farm is used as a case-study. The storage system design and evaluation processes use a computational tool developed in MatLab to simulate the wind farm operation with an energy storage system and computes the remuneration tariff. The energy storage design settles on a system of 5 MW with 30 MWh. The simulation results show a 2.1% gain in wind farm tariff and a improved adjustment on generation to the typical electricity demand curve. Considering the storage system design and an available storage technology survey, one concludes that redox flow batteries are the best suited to application, in spite of their present prices being not the most advantage.

Contribution of energy storage systems for power generation and demand balancing with increasing integration of renewable sources: application to the Portuguese power system

Increasing integration of renewable sources introduce some new issues on the operation of the power system, such as potential unbalancing between generation and demand, especially in off-peak periods with high levels of hydro generation. This scenario can get worse when associated with the installation of a nuclear powerplant, which operates on a must run basis. This paper analyses the contribution of energy storage systems use to avoid future power generation and demand unbalance in the Portuguese power system. Moreover it is also presented an overview of the available energy storage technologies and the role of power electronics on its appropriate operation.

How market power affects the behavior of a pumped storage hydro unit in the day-ahead electricity market?

The integration of large amounts of wind energy in power systems raises important operation issues such as the balance between power demand and generation. The pumped storage hydro (PSH) units are seen as one solution for this issue, avoiding the need for wind power curtailments. However, the behavior of a PSH unit might differ considerably when it operates in a liberalized market with some degree of market power. In this regard, a new approach for the optimal daily scheduling of a PSH unit in the day-ahead electricity market was developed and presented in this paper, in which the market power is modeled by a residual inverse demand function with a variable elasticity. The results obtained show that increasing degrees of market power of the PSH unit correspond to decreasing levels of storage and, therefore, the capacity to integrate wind power is considerably reduced under these circumstances.

Is the electric vehicle a solution for the wind power integration in the Portuguese power system

The integration of Plug-in electric vehicles in the transportation sector has a great potential to reduce oil dependency, the GHG emissions and to contribute for the integration of renewable sources into the electricity generation mix. Portugal has a high share of wind energy, and curtailment may occur, especially during the off-peak hours with high levels of hydro generation. In this context, the electric vehicles, seen as a distributed storage system, can help to reduce the potential wind curtailments and, therefore, increase the integration of wind power into the power system. In order to assess the energy and environmental benefits of this integration, a methodology based on a unit commitment and economic dispatch is adapted and implemented. From this methodology, the thermal generation costs, the CO2 emissions and the potential wind generation curtailment are computed. Simulation results show that a 10% penetration of electric vehicles in the Portuguese fleet would increase electrical load by 3% and reduce wind curtailment by only 26%. This results from the fact that the additional generation required to supply the electric vehicles is mostly thermal. The computed CO2 emissions of the EV are 92 g CO2/kWh which become closer to those of some new ICE engines.

Strategies for the integration of wind energy into the grid: An application to the Portuguese power system

The integration of wind energy into the grid is responsible for some constraints in the operation of the power system such as power unbalances between generation and demand due to the fact that higher wind power availability occurs in periods of lower demand.

Environmental dispatch of the portuguese power system for CO 2 emissions reduction

The present paper uses the concept of the environmental dispatch minimizing the CO2 emissions associated with the thermal generation of a power system. The environmental dispatch is applied to the Portuguese system and the respective results are compared to the results of a classical economic dispatch. The environmental and economic dispatch results comparison assumes the reference emissions allowances price of 20 euro/ton CO2. However, in order to understand the influence of the CO2 emissions allowances prices on the economic dispatch results, a sensitivity analysis was performed, considering different emissions allowances prices.

Estimating future power generation unbalance in the Portuguese power system due to increasing integration of renewable sources

Integration of renewable sources in energy production avoid the use of fossil sources, which are responsible for great environmental impacts and excessive dependency of energy imported products. However, increasing integration of renewable sources in a power system can introduce some new issues in its operation, such as potential unbalancing between generation and demand, especially in off-peak periods with high levels of hydro generation. This paper presents an estimate of the future power generation unbalance in the Portuguese power system due to increasing penetration of renewable sources.