Secondary Control for a D-STATCOM DC-Link Voltage Under Capacitance Degradation

Degradation of the dc-link capacitance due to aging, cell failure, and fuse failure has a negative impact on ac-side current THD distribution static compensator (D-STATCOM) power quality. These variations noticeably increase modulation index voltage ripple leading growing D-STATCOM. To solve this problem, article proposes modification mechanism as secondary control layer added common structure, nested loops. This upper-hand regulates set-point based magnitude remain in standard range indirectly. method works steady-state modes does not change primary controllers. Simulation experimental results show that properly controls device improve quality network under variations.