DISTRIBUTED STORAGE APPROACH VERSUS SINGULAR STORAGE APPROACH: A DYNAMIC STABILITY EVALUATION

Hailiya Ahsan and Mairaj ud Din Mufti

Keywords

Energy storage system (ESS), multimachine system, distributedenergy storage system (DESS), superconducting magnetic energystorage (SMES), faults, wind disturbance, discrete step aheadpredictive control (DSPC)

Abstract

In this paper, we report the modelling and dynamic performance assessment of a wind-penetrated multi-bus system incorporating a singular energy storage system (SESS)/distributed energy storage system (DESS). A superconducting magnetic energy storage (SMES) is chosen as the test bed technology through which real and reactive power (PQ) control is performed, with limits imposed on both power commands, so as to take the converter sizes into consideration. A discrete one step ahead predictive control strategy (DSPC) is delineated for controlling SMES dynamics. A second-order system is introduced to emulate the behaviour of the inherent SMES dynamic loop consisting of the grid side converter, DC link, chopper circuitry and superconducting coil. The DSPC introduces a dynamic saturation scheme while translating the bus frequency error into a reference power command, with all constraints on power in place. The storage topologies considered in this paper are as follows: SESS at an arbitrary load bus, SESS at the lowest-inertia generator bus and a comparatively small rating DESS at the two lowest- inertia generator buses. The system performance is tested against stiff contingencies in a turbulent wind background and the results obtained are compared. It is concluded that the lowest-inertia generator node catered DESS topology shows a highly improved dynamic performance, and the net distributed storage size required is lesser than any singular storage topology. The routine trade-off between higher cost and reasonable performance in case of a SESS is ameliorated by a DESS, making it an improved and a profitable option over SESS.

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