*8.2. Results and Discussion*

Tables 5 and 6, and Figures 5 and 6 summarize the results obtained by simulating the behavior of the day-ahead and intra-day markets with the help of the MATREM system, as well as considering the new contract and the new marketplaces. In particular, Table 5 shows the main results for the wind power producers, namely the energy value, the deviations and the remunerations. The table indicates that the STE contract (scenario S3) substantially reduced the deviations of the wind power producers, namely 56% in relation to the base scenario (see also Figure 5). In this way, the use of this contract decreased the cost of the deviations of WPPs by nearly 59% (see also Figure 6). However, WPPs were remunerated by the day-ahead clearing price, which was normally less attractive than the price of the tertiary reserve market (mFRR market). The participation of WPPs in the energy reserve marketplace (scenario S4) also increased the wind energy value (16% in relation to the base scenario S1). This result is explained by the high remuneration received by WPPs in the mFRR market, for their excess of energy (according to the actual operation of the Iberian market). In relation to the participation of WPPs in the renewable power band marketplace (scenario S5), they obtained a high levelized remuneration from energy. However, in comparison with the other scenarios, WPPs trade a lower quantity of energy, which results in a lower remuneration, and a higher cost with deviations.





Table 5 indicates that the use of the STE contract and the participation of WPPs in the energy reserve marketplace (scenarios S3 and S4) are particularly important, compensating their real-time lack of energy (i.e., wind power forecast underestimations). An analysis of the fifth column of the table shows that WPPs need to buy energy to fulfill their commitments with the DAM and the IDM. For the case of scenario S5, involving the participation of WPPs in the renewable power band marketplace, the benefits are not substantial for situations involving wind power forecast underestimations. In such situations, WPPs receive money for their excess of energy, instead of paying for their lack of energy.

**Figure 5.** Simulation results (reduction of deviations of the wind power producers).

**Figure 6.** Simulation results (reduction of deviation cost of wind power producers).

The sixth column of the table reflects to some extent the price of the secondary reserve market (aFRR market). WPPs receive a higher remuneration for power (scenario S5, corresponding to 29.06 e/MW), in comparison with the remuneration resulting from scenario S7 (28.83 e/MW), involving the new contract and the participation in the new marketplaces. This result is associated with a reduction in deviations that is not attractive, leading to a reduced power band (and bid).

Overall, the results of Table 5 show that the use of the new market products are beneficial to wind power producers. Accordingly, both market operators and independent system operators should take them into consideration, possibly with particular adaptations and/or extensions, in order to allow an effective participation of VRE producers in liberalized markets—that is, to provide the flexibility needed to integrate the increasing levels of renewable generation, maintaining the security of the power systems.

Table 6 shows the simulation results for the particular case of retailers. These agents use the STE contract only. The results indicate that the retailer agents reduce the deviations in 39% and the costs with deviations in 38%. Also, the results for scenario S7 show that the use of the STE contract and the participation in the new marketplaces by WPPs, as well as the use of the new contract by retailers, result in a significant decrease in the global imbalances (−49%) and the associated costs (−51%).
