Modelling and performance assessment of a standalone hybrid wind-diesel-superconducting magnetic energy storage system using four-quadrant operation of superconducting magnetic energy storage

In this article, a comprehensive model for power quality assessment of a standalone wind-diesel-superconducting magnetic energy storage system is developed using firing angle control scheme of superconducting magnetic energy storage unit. A four-quadrant operation of superconducting magnetic energy storage unit is proposed where firing angle of superconducting magnetic energy storage converter is controlled depending upon active and reactive power demand of wind-diesel system, under various disturbances. Superconducting magnetic energy storage is designed as a controllable current source capable of reducing both frequency and voltage deviations simultaneously. For continuous control of superconducting magnetic energy storage unit, a regulating variable is formulated which forces the superconducting magnetic energy storage current to return to its nominal value after handling a disturbance in order to handle a new disturbance. Frequency of the system is estimated using the concept of centre of inertia. System performance is assessed for disturbances of higher magnitudes. Complete modelling is carried out in MATLAB/Simulink environment, and simulation results demonstrate that the scheme gives expected results under load disturbance and wind perturbations.