Comprehensive Small Signal Stability Analyses for Hybrid Energy Storage System under Novel Transient Power Allocation Strategy

Multiple ESs with different characteristics help to constitute hybrid energy storage systems (HESSs) which should bear desirable power/energy density and dynamic performances. For this purpose, an advanced power allocation strategy combining traditional voltage-power (V-P) droops and integral droops (IDs), could be utilized. With the harmonized integration of V-P and ID, ESs with high energy density but restrained dynamics naturally respond to low frequency components of load power, while ESs with adequate power density but limited stored energy compensate the fast changes of power demand autonomously. Regardless of the merits of presented strategy, comprehensive stability analyses for a HESS with such power management scheme have not been studied. In this paper, the HESS is fully modeled in the small signal sense, with no dynamic state being neglected. The entire system stability is analyzed through comprehensive eigenvalue loci investigations. Tome domain simulations perfectly verify the effectiveness and accuracy of the eigenvalue analyzing results.