【摘要】 直流融冰装置是实现输电线路覆冰快速融冰的关键技术装备，对保障我国冰冻灾害频发地区电力系统安全稳定运行具有突出价值。其中，模块化多电平换流器（MMC）型直流融冰装置因其容量要求低、融冰高效、接线简单和无功需求低等显著优势，成为融冰技术发展的主要方向。然而，在现有直流电流控制方式下，MMC型直流融冰装置表现出明显的直流侧电压波动，进而导致环流增大、子模块电容电压不平衡等现象。为此，该文从控制系统角度出发，深入剖析直流电压波动的成因，提出一种基于调制直流电压取整与电流控制模式自适应切换的直流电流控制改进策略，并且引入电流状态监测机制，有效地控制实际融冰电流与参考值之间的稳态偏差。该方法可从根本上消除电压波动，通过逻辑控制实现直流电压质量的提升与融冰电流幅值工程要求的同步满足，且方案简便，无需额外硬件投入。仿真结果表明，所提方法能有效地抑制直流电压波动，改善MMC装置的环流和电容电压波动问题，验证了改进控制策略的可行性。更多还原

【Abstract】 Direct current(DC) de-icing devices are essential equipment for ensuring the safe and stable operation of power grids in regions frequently affected by severe icing disasters, as they enable rapid removal of ice accretion on transmission lines. Among various de-icing technologies, the modular multilevel converter(MMC)-based DC de-icing system has emerged as a mainstream solution due to its advantages of compact capacity, high efficiency, flexible connection topology, and low reactive power demand. However, under existing DC current control schemes, such systems generally encounter prominent DC voltage fluctuation problems. These fluctuations may induce circulating current distortion in converter arms and capacitor voltage imbalance among submodules, which pose significant challenges to system stability and long-term reliability. To address these problems, this study systematically investigates the underlying mechanism of DC voltage fluctuation from a control system perspective. Firstly, through mathematical modeling and theoretical analysis, the fundamental cause of voltage fluctuation is identified. It is demonstrated that the observed DC voltage oscillations do not stem from control precision limitations, but are caused by the clamping effect of the current cont rol loop on the modulation voltage. This clamping leads to frequent variations in the number of inserted submodules per phase, resulting in significant DC voltage disturbances. Secondly, based on the identified mechanism, a modified control strategy is proposed. The core idea combines modulation DC voltage rounding with adaptive switching of the DC current reference value. Specifically, the modulation voltage is constrained to integer multiples of the rated submodule capacitor voltage, stabilizing the submodule configuration. Simultaneously, the DC current reference value is adaptively adjusted according to the dynamic state of the system, thereby suppressing submodule switching fluctuations and improving DC voltage stability. Thirdly, to eliminate steady-state current deviations introduced by reference value switching, a real-time current state monitoring mechanism is further incorporated. This mechanism continuously detects and compensates for steady-state current errors, thereby enhancing current control accuracy and improving steady-state performance of the system. Finally, simulation studies verify that the proposed control strategy effectively suppresses DC voltage oscillations, mitigates arm circulating current distortion, and reduces capacitor voltage imbalance. As a result, both the dynamic performance and operational stability of the MMC-based DC de-icing system are significantly improved while still meeting the required deicing current amplitude without additional hardware or complex modifications. In conclusion, this research clarifies that:(1) The inability to maintain the modulation DC voltage as integer multiples of submodule rated capacitor voltage under existing control schemes is the root cause of DC voltage fluctuation in MMC-based DC de-icing devices.(2) The proposed control strategy, integrating voltage rounding and adaptive reference adjustment, fundamentally suppresses configuration-induced voltage disturbances. The additional current state monitoring further refines steady-state current accuracy. The solution offers a practical approach for improving MMC de-icing system performance within existing hardware configurations, without the need for supplementary filtering equipment or hardware redesign.更多还原