An auxiliary-power-compensation droop control strategy for multi-terminal flexible interconnected distribution network

Abstract

The emergence of multi-terminal flexible interconnected distribution network can effectively improve the consumption level of new energy and enhance the power supply quality of distribution network. At present, the droop control strategy is widely used in the modular multilevel converter (MMC) in multi-terminal flexible interconnected distribution network, which can adjust and distribute DC voltage and power autonomously according to the droop characteristic curve. However, this type of strategy is challenging to cope with the sudden working conditions. These conditions include the power reversal, the outage of station and large fluctuation of new energy sources, which can cause abnormal fluctuation of DC voltage. Therefore, this paper proposes a control strategy based on the auxiliary power compensation in the flexible interconnected distribution network to solve the problem. This compensation strategy introduces an auxiliary power reference and simplifies the control loop, effectively suppressing the power fluctuation and optimizing the dynamic performance of the system. Compared with the traditional improved droop control strategy, this strategy does not need to change the parameters of the control system, has a stronger ability to suppress the voltage fluctuation, and the response speed of the control system is faster. The reliability and effectiveness of the proposed control strategy are verified by simulation.

Keywords

• Multi-terminal flexible interconnected distribution network
• MMC station
• Droop control strategy
• Auxiliary power compensation