Differential flatness based control of supercapacitor substation for DC grid system

This paper presents a new control approach for dc-link stabilization in weak networks that use supercapacitors (SC) as the energy storage substation. A 4-phase parallel converter with interleaved switching technique is presented as a 2-quadrant SC converter, and a reduced-order mathematical model of the system is described for power plant control. Using a nonlinear control approach based on the flatness property, we propose a straightforward solution to dynamic and stabilization problems in the power electronics systems of networks, which is the key contribution described in this paper. To validate the proposed method, a hardware system is modeled using digital estimation with a DS1104 dSPACE controller platform. We analyze a prototype small-scale network that uses a 700 W six-pulse rectifier as a dc main generator and a 100 F, 32 V SC bank as an energy storage substation. Finally, the utility of the control algorithm is validated using experimental results measured during load cycles.