Performance Evaluation of a MW-Class SMES-BES DVR System for Mitigation of Voltage Quality Disturbances

Performance evaluations of a MW-class dynamic voltage restorer (DVR) system are presented for mitigation of voltage quality disturbances. A presag compensation strategy is introduced to lock the instantaneous magnitudes and phase angles of real-time line voltages, and thus to compensate the improper voltage components exactly after symmetrical or asymmetrical voltage disturbances. A 0.3-H/1.76-kA superconducting magnetic energy storage (SMES) magnet is used to cooperate with conventional battery energy storage (BES) device for developing a high-performance hybrid energy storage (HES) system. In the SMES-BES HES-based DVR system, the SMES can compensate the worst voltage sag for five cycles (1 MW, 100 ms, and absorb the highest voltage swell for six cycles (1 MW, 120 ms). The accessorial high-capacity BES device is subsequently discharged or charged for lasting long-time mitigation operations. Various simulation cases with regard to combined voltage sag, swell, and harmonic disturbances are carried out. The simulations and comparisons among the SMES-based, BES-based, and HES-based DVR schemes have demonstrated that the HES-based DVR scheme integrates the merits of fast response speed and high-power density from the SMES-based scheme, and the merits of low capital cost and high-energy density from the BES-based scheme.