Analysis and evaluation of the fault current limiting function of series custom power devices

Custom power devices are a set of devices designed to protect customers´ loads from power line disturbances. One class of custom power devices is the series-connected device (SC), such as dynamic voltage restorer (DVR) and series active power filter (SAPF). Recently, downstream fault limiting function of series custom power devices have been proposed and integrated in some literatures as an add-on feature, which can limit the flow of large line currents, and therefore restore the point of common coupling (PCC) voltage as well as protect the series custom power devices themselves. Though it sounds straightforward, there are many difficulties in specific implementation, such as it requires a 100% voltage compensation capacity and very quick dynamic control in some existing proposals. So the feasibility and performance of these methods should be carefully examined. But till now there is no literature available to clarify these problems. In this paper, advantages and disadvantages of existing measures are firstly presented and then new methods are proposed to further improve the feasibility and performance. Detailed analysis is presented and conclusions are given.