Damping of Subsynchronous Control Interactions in Large-Scale PV Installations Through Faster-Than-Real-Time Dynamic Emulation

Large-scale photovoltaic (PV) power plant has witnessed a dramatic increase in the integration into transmission and distribution network, manifesting subsynchronous control interaction (SSCI) when the host grid is weak. In this work, the oscillation modes of a typical PV network are analyzed, and a faster-than-real-time (FTRT) emulation is proposed for predicting the SSCI and consequently mitigating its impacts on AC grid by taking the effective active/reactive power control action. The electromagnetic transient (EMT) simulation is utilized to model the PV panels and converter stations to reflect the actual dynamic process. Meanwhile, the AC grid undergoes transient stability (TS) simulation to obtain a high speed up over real-time, and consequently, a power-voltage interface is adopted for the coexistence of different simulation methods. The reconfigurability and parallelism of the field-programmable gate arrays (FPGAs) enable the EMT-TS co-emulation strategy to run concurrently. With a remarkable 122 FTRT ratio, the proposed hardware emulation can provide an effective solution before the SSCI causes serious disruption following its detection. The hardware emulation results are validated by the off-line simulation tool Matlab/Simulink(R) and TSAT(R) in the DSATools((TM)) suite.