Voltage Profile Based Fault Detection

Fault location in a traditional power system is a challenging task. Electric power flows only in one direction: from the substation to the various loads. Therefore, when a severe short circuit fault occurs, there is a current rise with voltage sag near the faulted node or line and everything else that is downstream. If the fault protection system responds adequately it isolates the assumed faulted areas which are all the nearby and downstream customers of the actual faulted area.

In a system containing distributed resources (DRs), most fault location technologies ignore the presence of DRs by assuming either low DRs penetration or no power injection from DRs during a fault. The few technologies that consider the presence of DRs have not considered a current limited system when a fault occurs.

As the amount of local generation (PV, microturbines ... ) is increasing, the existing distribution systems fault location methods do not always apply because of various reasons including cost, complexity of the system due to mesh-like system topology, and bidirectional power flow. This FSU invention takes advantage of the system topology, the presence of the controllable voltage source convertors (VSCs), and the change of the voltage profile with the presence of the fault. Using the VSCs to help locate the fault will help overcome the issue of relying on the measured value of voltage when the voltage has completely collapsed in a section because of a fault in the distribution system. Instead of hindering the fault location process, the VSCs are used to help support the voltage, locate the fault, and provide fast restoration.