## 3 Simulations Summary and Metrics to Evaluate the Results  
To be as clear as possible, after showing the model layout, this section lists the simulations performed, with particular attention on detailing the aim of the different simulation categories and the metrics that will be used in next section to evaluate the results. It is important to remember which situation this model is describing: a small island power system characterized by the presence of three equivalent generating units (PV, wind, and synchronous generator) and an equivalent load, which can be seen as a grouping of all the smaller loads present in the island. This situation, in fact, is the one in which a mismatch between the active power produced and consumed can have more serious effects on frequency stability, due to the small size of the power system, its lack of interconnections due to the remote geographic position, as well as the high penetration of renewable sources that is usually observed on the islands. The simulations can be divided into some categories, as a function of the perturbation introduced with respect to a common reference condition. It is thus fundamental to describe this reference condition before going on. The common reference condition that has been chosen from now on will be indicated with \"_base case_\" and is characterized as follows:  
* Participation factors of the three equivalent generating units: \(p_{wind}=0.2\); \(p_{synchronous}=0.7\); \(p_{pv}=0.1\) (30% of renewable penetration on nominal power basis). Figure 9: Extended OPPT Method [24]. * \(H_{eq}=2.88\) s [24]; \(D=1\)[32]. * Incoming wind speed at \(t=0\) s: 9.6 m/s for constant wind simulations; 11.457 m/s for real wind profile simulations. * Irradiance at \(t=0\) s: 1000 W/m\({}^{2}\). * Cell temperature: 25 \({}^{\circ}\)C.
* Constant load power requirement. In each simulation, a modification with respect to this base case is introduced to study different aspects linked to the frequency stability. As stated before, the simulations can be grouped as a function of the perturbation introduced. In particular, the situations compiled in Table 2 have been studied. Furthermore, to have other points of view on the system, each simulation is performed on four different versions of the complete system:  
* Primary frequency control provided only by the synchronous generators (wind turbines without virtual inertia control, PV without power reserve control). * Primary frequency control provided by synchronous generators and wind turbines (Extended OPPT Method enabled). * Primary frequency control provided by synchronous generators and photovoltaic strings (Power Reserve Control enabled). * All the generators participate in the primary frequency control (from now on it is denoted as _complete FC_). The first scenario is representing the current situation in most of the power systems, since the renewables are mostly operated in their MPP condition. The fourth scenario, on the other hand, could represent a future situation in which renewables are flexible and able to help synchronous generators (or displace them) in balancing the frequency of a power system. This captures the interaction between the various controllers, the help that the renewables controlled with the updated logics can provide to the system, and the impact of each technology in frequency stabilization. The final summary of the simulations performed on the model is reported in Tables 3 and 4. A number has been used to designate each of them, so that the results can be commented in a clearer way. As is probably noticed, this work does not analyze the case of a generator loss. Indeed, this kind of model is not capable to catch that kind of event, excluding a loss of a part of the photovoltaic generation. This is intrinsic to the model developed for the system, in which the generators have to be intended as an \"equivalent\" of all the similar generating units present in the system. With some modifications, it is just possible to model the loss of the entire fleet of wind or synchronous generators.