储能换流器动态过程分析与前馈控制改进策略

低压直流配电网通过母线分段降低了每段母线所承担的功率容量,使大范围内的直流供电成为可能。考虑配电网负荷多元化及用电的随机性,直流母线电压会时有波动,因此需在敏感负荷区配置储能装置,以提高供电质量及供电可靠性。为此,文中首先选取并实现了三重化DC/DC换流器拓扑以增大储能换流器(SC)容量,以及提高母线失电状态下储能装置的供电时间;同时基于载波移相的定电压控制,在减小电压偏差的同时降低电流纹波,从而提高电能质量。其次,为应对配电网内功率波动,缩短暂态响应过程,对SC输出电流的动态响应过程进行了深入分析并建立了小信号模型;基于动态过程分析设计了将电压偏差引入电流内环的前馈控制策略,且进行了缺陷分析与改善设计。最后进行了实验验证。

Dynamic Process Analysis and Improved Feedforward Strategy for Storage Converters

Low voltage direct current(LVDC)distribution network can reduce the power capacity of each bus section by sectionalizing buses, so it is possible to provide DC power in a wide range. Due to the diversity of distribution network load and the randomness of electricity consumption, the voltage of DC buses fluctuate frequently, and the energy storage devices should be arranged in a sensitive load area to improve the quality and the reliability of power supply. For this purpose, a topology of a triple-phase DC/DC converter is firstly chosen and implemented to increase the power capacity and power supply time of the energy storage devices in the situation of bus failures. Meanwhile, the constant voltage control based on the carrier phase shifting is adopted to reduce the voltage deviations and current ripples, thus improving the power quality. Secondly, to cope with the power fluctuations of distribution networks and to shorten the transient response time, the dynamic response process of the storage converters output current is analyzed in detail, and the small signal model is built. Thirdly, based on the above analysis, a feedforward control strategy is proposed by introducing the voltage deviation into the inner current loop, and the strategy''s drawbacks are analyzed and improved. Finally, an experimental verification is implemented.