Performance Evaluation of a MW-Class SMES-Based DVR System for Enhancing Transient Voltage Quality by Using &ITd&IT-&ITq&IT Transform Control

A conceptual design and performance evaluation of a megawatt (MW) class dynamic voltage restorer system are presented for mitigation of voltage-quality disturbances. To detect possible voltage disturbances quickly and, thus, to compensate the transient voltage waveform immediately after the occurrences of voltage disturbances, a new instantaneous d-q transform detection method is introduced. Subsequently, a pre-sag compensation strategy is introduced to lock the instantaneous magnitudes and phase angles of real-time line voltages for compensating the improper voltage components completely. A 0.3-H/1.76-kA superconducting magnetic energy storage (SMES) magnet is structurally designed for MW-class power exchange operations. Various simulation cases with regard to voltage sag, voltage swell, and overvoltage disturbances are carried out. The simulations and comparisons among two control schemes have demonstrated that the reductions of waveform distortions, the stabilization of root-mean-square voltages, and the suppressions of peak voltage come mainly from the cooperative operation of the d-q control method and the fast-response SMES device.