Control of the MMC converter for grid connection enhances noise immunity using LADRC control

Abstract

The MMC converter stands out as a promising solution for integrating distributed energy sources and HVDC systems with the grid. However, the inherent complexity of the MMC structure, characterized by a large number of submodule (SM) units, presents challenges during operation, particularly in direct modulation scenarios. These complexities manifest as dynamic processes that can induce interference, significantly impacting grid connectivity, especially in weak power grid scenarios. This paper presents a control solution aimed at mitigating linear active disturbances by leveraging the Linear Active Disturbance Rejection Control (LADRC) technique. The proposed controller, when integrated with the Nearest Level Modulation (NLM) method, enables the generation of 2N+1 AC voltage levels with low-frequency closing pulses for the valves. This approach shows promise in enhancing system stability owing to its robust anti-interference capabilities and superior tracking performance. The methodology is rooted in a small-signal impedance model that accounts for frequency coupling dynamics. The efficacy of the proposed solution is validated through simulations conducted by using Matlab/Simulink software.