Fault current limiting function of dynamic voltage restorer utilizing signals from existing protective relays

Dynamic voltage restorer (DVR) is a series custom compensator used in power distribution network; however, due to the fact that it is connected in series with the distribution line, DVR would suffer from downstream faults. To limit the flow of large fault currents and protect DVR itself as well, a fault current limiting function is proposed in the DVR control strategy. Fault current limiting function of DVR will be activated by the protection system and then DVR will start injecting a series voltage to the line in such a way as to limit fault current to an appropriate level (in accordance with required sensitivity of the protection systems). The contribution of this proposal is the use of signals from existing feeder protection system to activate the DVR. This will simplify the structure of DVR because the extra build-in fault detection module is not required. Moreover, it will ensure proper coordination between DVR and protection systems.