Integrated Coordination Improvement of Droop Control for Medium and Low Voltage DC Distribution Network

In view of the traditional droop control, when the DC distribution network is disturbed or faulted, the transient voltage stability of the DC distribution network is poor due to the nonlinearity of the system and the fixed droop coefficient. The actual operation of the converter station margin cannot be considered, which is prone to full load problem. In order to solve the above problem, firstly, we propose an adaptive comprehensive coordinated improvement droop control strategy, including an outer loop adaptive droop control part which considers the power margin and voltage deviation compensation respectively, as well as an inner loop current adaptive discrete sliding mode control part. Moreover, the power margin and voltage deviation of each converter station are considered comprehensively, through a real-time adaptive adjustment of the droop coefficient, to reasonably distribute the unbalanced power within the DC grid after disturbance and reduce the deviation of the DC voltage. Finally, we use a four-terminal medium and low voltage DC distribution of the system to attain the simulation results as an example which verifies the effectiveness and correctness of the proposed control strategy. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.