Investigation of the control of a converter topology interfacing an energy storage with the dc link of a VSC

Integration of energy storage (ES) into a static synchronous compensator (StatCom) makes it possible for the StatCom to provide a certain amount of active power as well as reactive power support. The possible benefit of the additional active power support of a StatCom can be power oscillation damping capability, mitigation of phase-jump related disturbances, etc. Direct connection of an ES device to the dc link of the VSC incurs high voltage rating of the VSC due to the considerable voltage swing associated with the ES device. In order to reduce the total cost, a dual thyristor converter topology has been proposed as the interface between the ES and the dc link of the voltage Source Converter. In this paper, the dynamics of the proposed system are investigated. Control strategies are proposed and verified by simulations with PSCAD/EMTDC. A comparison is made between two control methods.