DFIG Active Damping Control Strategy Based on Remodeling of Multiple Energy Branches

Concerning subsynchronous oscillation caused by the integration of doubly-fed induction generator (DFIG) to power grid via series compensation line, an active damping control strategy based on remodeling of multiple energy branches in DFIG is proposed. First, according to the flow path of oscillation components, energy branches in DFIG are divided. Second, potential energy and dissipation energy are defined characterizing accumulation and consumption of energy during oscillation. Then, by analyzing the contribution of energy branches to potential energy and dissipation energy, key energy branches affecting the stability of system are screened. On this basis, the relations among stator voltage, potential energy, and dissipation energy are established, and frequency-dependent energy compensation functions in key branches are derived. By assessing their impact on low voltage ride through (LVRT) performance of DFIG, the compensation branch compatible with DFIG fundamental frequency characteristics are screened. Then, take sub/supersynchronous frequency stability coefficient ratio as the objective function, and the requirement on stability in sub/supersynchronous frequency band as the constraints. The compensation branch parameter optimization scheme is established. Finally, a test system is built in RT-LAB for verification. Simulation results demonstrate that, the proposed strategy can realize active damping control in multiple oscillation cases, and guarantee the stability of system in full frequency band. Besides, the strategy does not affect LVRT performance of DFIG and is well compatible with DFIG fundamental frequency characteristics.