Edgardo D. Castronuovo

Optimal Operation of Offshore Wind Farms With Line-Commutated HVDC Link Connection

This paper aims to calculate the optimal operation of offshore wind farms (OWF) working with wind turbines based on doubly fed induction generator (DFIG) technologies, and with a high-voltage dc transmission connection. The objective of the optimization problem is to maximize the active power output of the arrangement, while considering certain factors, i.e., the restrictions imposed by the available wind power, the capability curve of the DFIG, the dc-link model, and the operative conditions. The accomplishment of this aim implies setting, adjusting, and operating the system under study in order to produce a reliable and cost-efficient electric energy supply. A realistic simulation test case is performed to evaluate the proposed method, and the optimal operation analysis takes into account different wind speeds and high-voltage dc-link lengths. The results show the effectiveness of the proposed method, demonstrating the advantages of using the reactive control performed by the DFIG to manage the operational requirements of the dc link.

Optimal geometric configurations for mitigation of magnetic fields of underground power lines

In this article, a nonlinear optimization problem for calculating the optimal configuration of underground power lines is proposed. In the analysis, considerations of geometry, economy and maximum magnetic field are taken into account. The cable bundles are allowed to be placed freely in the available space to achieve the most economical configuration. Real test cases are used to evaluate the methodology. Based on the results, it is observed that the rotation of the cables is important to improve interaction and decrease the magnetic field in desired locations. These rotations can be obtained simply through the appropriate manipulation of the cables during the construction phase. Negligible magnetic fields can be obtained in the measurement plane when the optimal geometrical configuration is used. Sensitively analyses are performed in the solution, for evaluating the effect of differences in angles and modules of the currents in the cables.

Forecasting for storage management

Wind and solar productions have increased worldwide in recent decades. These renewable resources are recognized as having advantages over other conventional sources of electricity. However, the fluctuating characteristics of wind and solar resources cause certain operational problems in electrical systems. Therefore, many researchers have considered complementing wind and solar power with storage devices. Hydro-pumped storage is the most diffuse type of storage currently used in power systems. The present study is a methodological review of the main strategies proposed for the combined management of electricity generated from renewable resources that are not fully controllable and hydro-pumped storage plants and classifies the approaches on the basis of the expected goal of the complementation.

On the operational optimization of large hydrological basins

The operational optimization of large hydrological basins still remains a challenger issue. Large travel times of the water between upstream reservoirs and the mouth of the river, several days as horizon of optimization, very nonlinear equations, uncertainties and ecological constraints result in complex optimization problems with difficult solutions. The present work uses a new formulation, with continuous variables and restrictions expressed as linear equations. Upper and medium Guadalquivir basin is analyzed, including 18 hydro plants with different characteristics and goals of operation. Considerations about uncertainties in the production are formulated. The algorithm has an adequate performance, requiring small cpu times to reach the solution.

Coordination Between Wind Farms and Storage Devices, Technical and Economic Aspects

The increased participation of the wind power production in the electric systems requires the analysis and adoption of new operational techniques. One of the alternatives most frequently cited in the literature is the coordination of wind farms with storage devices, with different purposes. The present chapter studies different approaches for this methodological option, presenting results from the recent literature. Also, this chapter presents an alternative for calculating the optimal operation of storage devices in coordination with wind generation. Finally, the interaction of wind farms with reserve markets is fully explained.

Economical balances within a delegate dispatch of renewable generations

The modern technologies used to generate electricity from renewable sources allow some control abilities of the production. These abilities can be required when the system is at risk by the System Operator. When facing a contingence, the System Operator could specify maximum values of renewable production in zones of the system. Delegated Dispatches of renewable production are zonal intermediate entities, responsible of calculating the optimal profile of renewable generations in the region reaching the System Operator restrictions. In the present paper, the economic exchanges in a Delegated Dispatch are analyzed. The renewable producers bid control prices to the Delegated Dispatch in a market-based procedure. After the operation, the control costs are proportionally shared among the producers. A realistic test in a Spanish distribution grid shows the efficiency of the proposed method.