The chain cell PFC [power flow controller]

A proposal is made for a new style of power flow controller (PFC) based upon multi-level chain cell converters. In general, multi-level converters are attractive when designing high power FACTS devices as they are capable of providing high power quality, without the need for phase-shift transformers (which are required by multi-pulse converters). The chain cell converter is particularly attractive as its component count rises linearly with number of levels. Chain cell converters are not suited to processing real power as they cannot easily share a common DC-link, hence transfer of power between converters cannot be achieved by using a back-to-back configuration. However, a circuit topology is introduced that allows two chain cell converters, connected in a shunt-series arrangement, to control the real and reactive power flow within a transmission line. The circuit as a whole can process real power and is shown to offer similar functionality to the unified power flow controller (UPFC). The proposed circuit is examined through both DQ models and time domain simulation