Separated Phase–Current Controls Using Inverter-Based DGs to Mitigate Effects of Fault Current Contribution from Synchronous DGs on Recloser–Fuse

Abstract

Synchronous distributed generators (SDGs) significantly affect recloser−fuse coordination due to the high fault current contribution. This paper proposes a separated phase−current control using inverter-based distributed generators (IBDGs) to remove the effects of fault current contributions from SDGs during unsymmetrical faults. The three-phase current produced by IBDGs is independently controlled. While the total fault current is reduced by adjusting the current phase angle in the faulty phase, the energy in the DC-link capacitor ( C d c ) is delivered to the grid in order to avoid the rise of DC-link voltage ( V d c ) by means of injection of the active current into the nonfaulty phase. To maintain the proper grid voltage, the voltage regulation feature is installed in the IBDGs. Moreover, current estimations programmed within the IBDGs are introduced to avoid the performance degradation of separated phase−current controls caused by phasor measurement units (PMUs). The dynamic performance of the separated phase−current controls using IBDGs was evaluated using an IEEE 34-node radial test feeder. According to the simulation results, the IBDGs could eliminate the effects of fault current contributions from the SDG without interruption since the disconnections caused by excessive V d c were prevented. They could also regulate the grid voltage in the nonfaulty phase.

Keywords

• fault current contribution
• inverter-based distributed generator
• synchronous distributed generator
• smart grid
• recloser–fuse coordination