Optimal allocation of energy storages: A perspective of system inertia support

Abstract

The fluctuation and intermittence of renewable energies are raising concerns about the economical scheduling and the security operation of power system. The shift from traditional fossil energies to renewable energies causes the shortage in rotational inertia and affects the frequency stability of power system. One of the promising solutions is to construct a certain number of energy storage facilities with virtual inertia in suitable places for improving stability, which simulates the characteristics of traditional generators through specific controls over the converters of energy storages. While transient issues about the optimal allocation of energy storages have not been well addressed. From the perspective of system inertia support, the system state-space model is firstly established in this paper. Then the guidance of allocating energy storages optimally is provided via ℋ2-norm calculation and projected gradient derivation. Moreover, for the purpose of evaluating system disturbances more precisely, an appropriate method for equivalenting the disturbance strength of nodes is proposed, the advantages of which are later examined in comparative simulations. The contribution of this paper is verified through the time-domain simulations of the New England 39-bus system together with the illustration and comparative analysis of the optimal results.