Elena Sáiz-Marín

Economic Assessment of the Participation of Wind Generation in the Secondary Regulation Market

The aim of this paper is to analyze the profitability of wind technology as a potential participant in the frequency regulation, specifically in the secondary regulation market. The study is conducted for the Spanish system using existing market rules. However, although this system has some peculiarities the main methodology could be applied in other systems. Firstly, a bibliographical review of the relevant technical possibilities of this technology is carried out. Then, a simulation study based on real data is conducted in order to evaluate the maximum possible incomes. Later, a specific offer strategy is proposed and the income is estimated based on statistical modeling and checked by simulating its performance using the actual and forecasted productions of a wind portfolio. It is concluded that under the current generation structure and regulatory framework in the Spanish system, the incomes obtained from the participation of wind technology would be modest. However, secondary regulation by wind generators might facilitate higher penetration levels of this technology. In the long term, with expected wind generation subsidies much reduced, a greater need for regulation reserves and a possible increase in regulation prices, regulation-related incomes might become a sizeable fraction of the total income of wind generators.

Local Hosting Capacity Increase by Means of Wind Farm Voltage Control Provision

This paper identifies when the transmission network local hosting capacity for a wind harvesting network may be limited because of steady-state bus voltage limits. In addition, the paper addresses how with the wind farm voltage control provision, such constraints may be overcome and the local hosting capacity can be increased. To answer these questions, actual Spanish system data is used on different network models of increasing complexity. Firstly, a simplified model of both transmission network and harvesting network is discussed to show that generally, only buses with low short-circuit power and low or high reactance-resistance ratio may limit local hosting capacity significantly. Secondly, in order to assess how modeling simplifications affect the results, the full model of an actual Spanish harvesting network is considered: the real reactive capability of the harvesting network at the transmission network connection node is computed and the local hosting capacity recalculated. Finally, in the last step, the results of the aforementioned simplified models are validated using the complete model of the Spanish transmission network. In addition, a complementary area hosting capacity analysis is included in order to show the importance of steady-state bus voltage constraints when large amounts of power need to be transported over long distances.

Power losses minimization within Spanish wind farms evacuation networks

The aim of this paper is to evaluate the influence on power losses of the provision of voltage control by wind farms within the grid that connects them to the transmission network. In addition, the paper estimates the economic profit or cost that this technology could obtain in case of providing voltage control. This paper concentrates on the Spanish situation, where wind farms are connected to the transmission network by an evacuation network without containing loads. Thus, from the economic point of view, just the wind farms owners are affected. The results presented in this paper have been obtained for a real representative Spanish wind evacuation network.

Long Term Maintenance Optimization of CCGT Plants

The rising share of renewable energies within the generation mix has reduced the load factor of actual CCGT power plants. In this way, a more flexible operation of this technology with an increased number of annual start-up cycles is needed. Since CCGT design assumed a base load operation at nominal power with a few number of annual start cycles, plant owners have to face higher maintenance costs, reliability reduction and lower market incomes. This paper presents a mixed-integer optimization model that schedules the long term maintenance planning based on the daily operation of a CCGT plant in order to maximize its global profit. The model is illustrated with an actual CCGT plant operating in the Spanish power system.

Optimal Band Provision by Wind Generation in the Spanish Secondary Regulation Market

Participation of wind generation in the secondary regulation has both technical and economic interest. From the technical point of view, a higher wind penetration can be facilitated. From the economic standpoint, wind generators can make a profit by providing regulation that surpasses the loss by not selling the maximum possible amount of energy. The aim of this paper is determining the optimal quantity of the bid presented by the potential participation of wind generation at the secondary regulation market. The methodology proposed is illustrated using real data of forecasted and real wind power production of a portfolio of 730.58 MW for year 2008 in Spain.