Control Strategy of Flexible DC Distribution System Based on Droop Characteristics

The flexible DC power distribution system could operate in various ways and the source-load power fluctuations have high-frequency randomness. In order to solve the problems of low power quality, unreasonable power distribution and unsatisfactory voltage dynamic regulation under traditional droop control, a control strategy combining adaptive control, predictive control and droop control was proposed. Firstly, the DC voltage deviation compensator was designed to track the stable working voltage of the system in real time, and the dynamic influence factor was set for the traditional droop coefficient. The droop coefficient was adaptively adjusted, and the power was reasonably distributed according to the power margin of each converter station. Then the predictive control method was introduced in the inner current control loop to avoid the weakening control effect due to improper PI parameter tuning, and further improve the dynamic response capability of the system. The simulation model of double-ended flexible DC power distribution system was built on PSCAD, and the simulation of different operating conditions verified the effectiveness of the strategy.