研究了交直流互联电网直流功率调制相关问题，包括直流功率调制信号的选择、直流调制控制器的设计及其参数协调优化、负荷特性及低压限流单元对直流功率调制的影响等。针对大方式直流功率调制下，紧急功率支援的投、撤时间掌控问题，引入了最优时间控制理论；针对紧急功率支援的功率提升量、回降量、提升速率、回降速率、支援开始时间，引入了扩展等面积和遗传算法对以上参数进行优化，指出了有功调制有必要和无功调制相结合，最后提出了相关建议和展望。

At present, most DC systems are taken advantage to enhance AC system stability with rapid DC modulation characteristics, therefore, research on DC power modulation is practically important, especially on emergency DC power support (EDCPS). In this paper, some research issues related to DC power modulation (DCM) in AC/DC hybrid system are presented, including selection of DCM input signal, DCM controller design, co-ordination and optimization of its control parameters, the affect of both load characteristics and voltage dependent current order limiter (VDCOL) on DCM, as well as the research on large power flow modulation, especially EDCPS. As far the time control for EDCPS, the optimal sequence time control theory is introduced, and both extended equal area criterion (EEAC) and genetic algorithm are introduced to optimize some parameters in EDCPS, including DC power increment, drop amount, corresponding changing rate and starting-support time. What is more, DC power modulation should be associated with reactive power modulation in converters, and finally some research suggestions and prospects are brought forward.