一种适用于多电压等级直流配电网的分散式双向电压支撑控制方法

新能源发电、储能系统、直流负载接入直流配电网,可减少DC/AC转换环节,简化控制,提高系统运行效率,故近些年来直流配电网受到了广泛关注.采用电力电子装置构建多电压等级直流配电网,具有更加灵活的拓扑结构、更加多变的运行形式及更高的供电可靠性,但同时给配电网的稳定高效运行带来了诸多挑战.针对多电压等级直流配电网中子网互联的双向DC/DC变换器,基于变换器两端口电压,提出了一种分散式归一化电压平方差控制方法,结合储能变换器的功率-电压平方下垂控制,实现不同电压等级母线电压控制归一化视角下相等,为各电压等级母线提供不间断的电压支撑,并可使系统在储能切入/切出、电压等级拓展、接入中压直流配电网等多种运行模式间灵活切换.对所提控制方法的可行性与稳定性进行了分析,并基于MATLAB/Simulink对其有效性进行了仿真验证.

Decentralized bidirectional voltage support control method available for multi-voltage level DC distribution network

The integration of new energy power generation, energy storage system and DC load to DC distribution network can reduce DC/AC conversion stage, simplify control and improve system operation efficiency. Therefore, DC distribution network has received widespread attention in recent years. Using power electronic devices to construct a multi-voltage level DC distribution network has more flexible topological structure, more variable operation forms and higher power supply reliability, but it also brings many challenges to the stable and efficient operation of distribution network. Aiming at the bidirectional DC/DC converter for sub-network interconnection in multi-voltage level DC distribution network, a decentralized normalized voltage square variance control method is proposed based on the two-terminal voltage of the converter. Combined with the power-voltage square droop control of energy storage converter, the control method can realize the equalization of bus voltage with different voltage levels under normalization perspective, provide uninterrupted voltage support for the bus of all voltage levels, and enable the system to switch flexibly among multiple operation modes, such as switching in and out of energy storage, expansion of voltage level, integration to medium voltage DC distribution network, and so on. The feasibility and stability of the proposed control method are analyzed, and its effectiveness is verified by simulation based on MATLAB/Simulink.