Ripple suppression scheme of DC distribution network based on storage converter control

Abstract

In the DC distribution network connected to the middle voltage AC system, when the three-phase load of the AC system is unbalanced or an asymmetric fault occurs, there will be an AC component in the power flowing into the DC bus, which will cause ripples in the DC bus voltage The component affects the power quality of the DC distribution network and threatens the normal operation of the electrical equipment in the DC distribution network. Therefore, on the basis of the original bidirectional DC/DC converter, this paper adds a compensation capacitor and additional inductance on the low-voltage side to realize the separation control and output of the energy storage current and the ripple suppression current. Aiming at this improved SC topology, a VPI control-based energy storage converter control strategy is proposed, which realizes the non-difference tracking of the ripple voltage. Finally, a DC distribution network simulation model with VSC converter, DC load and DC battery energy storage was built in Matlab/Simulink. Under the premise of safe operation, by comparing with the original proportional outer loop voltage control, the DC distribution network voltage with smaller ripple is obtained, which verifies the advantages of the control method proposed in this article.