Cooperative Operation of Online Current Limitation Strategy and SFCL in PV-STATCOM Application Scenario Under Asymmetrical Faults

Grid-connected photovoltaic systems (GCPVS) should remain grid-connected and inject specified reactive current in accordance with Fault-ride-through (FRT) requirements. To minimize voltage ripples on the DC link voltage and restricts the maximum phase currents, a coordinated Positive-Sequence (PS) and Negative-Sequence (NS) control along with Online Current Limitation Strategy (OCLS) is applied in GSC. A corresponding power-reduction strategy is modified for BC control systems. SFCL is tentatively applied to improve PV terminal voltage and improve transient characteristics under the asymmetrical faults. By introducing SFCL in OCLS scenarios, R-value of SFCL is reduced and performance of OCLS is significantly improved.