Control of a battery energy storage system to compensate for ADN equivalents inaccuracies

Abstract

This paper proposes a new application for a Battery Energy Storage System (BESS) connected at the main substation of a distribution grid. It consists of controlling the BESS in such a way that the net active and reactive powers entering the distribution network matches as closely as possible the response of a dynamic equivalent model of the latter, used in large-disturbance dynamic simulations of the transmission system. Thus, the BESS compensates for the inevitable inaccuracies of the equivalent, which can be used with higher guarantee of accuracy. Its active and reactive powers are controlled without resorting to any model of that grid. Simulations results are reported on the CIGRE MV test system. Good performances are found in response to disturbances of various severities. The proposed approach would lead to a new service for the BESS, in addition to other purposes for which it has been installed. • A BESS connected at the main substation of a distribution grid can be controlled in such a way that the response of the distribution grid to large disturbances is approaching the response of an equivalent. The latter is a reduced-order model, used in simulations of the transmission system. The overall objective is to compensate for inevitable inaccuracies of that model, and, hence, increase the reliability of those simulations. • The control of the BESS involves the measurement of the voltage phasor at the main substation of the distribution grid. That measurement is used to simulate in real-time the active and reactive power responses of the equivalent. • PI controllers are used to adjust the active and reactive powers produced by the battery and bring the closest to zero the difference between the simulated active and reactive power responses of the equivalent and those of the distribution grid (measured at the main substation). • By compensating the inaccuracies of the equivalent, the proposed control allows less frequent updates of the latter. • The active and reactive power responses of the battery can also be used as an indicator of the accuracy of the equivalent. Indeed, the less the battery is requested to vary its active and reactive power outputs in the event of a large disturbance, the better is the accuracy of the equivalent.