Test Requirement:The purpose of the test is to check the function of automated reduction of active power in case of overfrequency, through the extrapolation of a graph of P as a function of frequency.The following sequence of steps must be performed: - storage system connected to the bidirectional converters, three sequences of measurement, starting from 100% (sequence A), from 50% (sequence B) and from 0% (sequence C) of PSMAX, or PNINV for integrated storage system.- For storage system connected to unidirectional converters, two sequences of measurement, starting from 100% (sequence A) and from 50% (sequence B) of PSMAX, or PNINV for integrated storage system.For all of the measuring sequences (sequence A, B and if required, C), gradually increase the frequency (of the network simulator or signal generator) and measure the value of power (average values of 0.2 s). The test can be performed either by means of a network simulator capable of changing frequency parameters available at the output terminals of the inverter, or directly on electrical grid. In this case it is allowed to adjust the frequency parameters that control the power regulation system in the case of overfrequency, so as to simulate the progressive increase in the frequency and the subsequent coming back around the nominal value.At the end of each sequence the frequency shall be reset to a value close to the nominal one, in order to verify that time requirements are fulfilled for the gradual restoration of the power delivered before the transition frequency (i.e. before exceeding the limit of 50.2 Hz).