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间歇性新能源功率传输需要高压直流系统具备更灵活的调节能力.基于直流系统换流器稳态模型,为实现功率的调节,换流阀的控制角约束被适当放宽,提出一种在给定换流变变比条件下的直流控制策略.换流变初始变比针对该策略进行了优化.该策略对控制角、无功补偿量及换相失败的影响均进行了分析.新方法运行于较大的控制角,增加了无功损耗但有利于抑制换相失败.CIGRE标准测试系统验证了本文方法的正确性和有效性.“,”Intermittent new energy delivery requires increasing the flexibility of ultra-high voltage direct current (DC) power adjustment. Based on a converter steady-state model and a DC power model, the control angle constraints of a converter valve are relaxed for power regulation. In this paper, a flexible DC power control method based on a fixed tap changer position is proposed. The initial ratio of the converter transformer is optimized. The effects of the fixed-tap changer position control on the control angle, reactive power compensation, and commutation failure are analyzed. The new control method allows a DC system to operate at a large angle and increase the additional reactive power loss while improving the commutation security margin. Steady-state and electromagnetic transient simulations in the CIGRE test system verify the validity of the method proposed in this paper and the correctness of the analysis conclusions.