A Converter Topology Suitable for Interfacing Energy Storage with the DC Link of a StatCom

Voltage source converters (VSC) have been widely utilized to provide instantaneous reactive power support to power systems, an application referred to as static synchronous compensators (StatCom). Integration of energy storage (ES) into a 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 disturbance, etc. Direct connection of ES device to the dc link of the VSC incurs unnecessary high voltage rating of the VSC due to the considerable voltage swing associated with the ES device. This paper proposes a thyristor converter topology as the interface between the ES device and the VSC dc link. With the proposed interface, the dc voltage of the VSC can be kept constant and thus lower the VSC rating and cost.