Integrated fault ride through control for multi-port DC distribution system with distributed photovoltaic generation

Due to the high penetration of renewable energy, multi-port DC distribution system with distributed photovoltaic generation should have the ability of fault ride through when the AC lines of the grid connected converter fail. However, the grid connected converter and photovoltaic DC transformer are different in capa-city and control mode. Even if they can communicate and coordinate with each other at high speed during fault ride through period, due to the difference of power regulation response of different converters, the DC bus voltage is prone to large fluctuation, and then cause the whole system trip-off from grid. Therefore, a variable power control method based on the regulation of photovolatic array port voltage is proposed, which can dynamically compensate the active power of the DC distribution system. The DC bus voltage can be quickly recovered to the rated operating point, and the wide-range fluctuation of DC bus voltage caused by AC fault is solved. The setting principle of adjustment coefficient and the selection of voltage threshold are given to realize reliable fault ride through. Results of PSCAD simulation show that compared with the traditional control strategy, the proposed method can effectively and quickly adjust the active power of photovolatic station under different fault levels and different active power before AC fault occurs, thus avoi-ding converter blocking in DC distribution system and ensuring the realization of fault ride through of the grid connected converter. © 2021, Electric Power Automation Equipment Press. All right reserved.