基于固态变压器的交直流混合配电系统协调运行控制策略

Coordinated Operation Control Strategy of AC/DC Hybrid Distribution System Based on Solid-state Transformer

基于固态变压器(solid state transformer, SST)的交直流混合配电系统对于大规模消纳可再生能源具有重要意义,可靠的控制策略是保障混合配电系统稳定运行的关键。提出了基于SST的交直流混合配电系统协调运行控制策略,子网内“源、储、荷”的控制策略可自主实现子网内部的功率平衡;低压级能够维持低压交流母线电压,并实现交直流子网的互济互助;隔离级耦合中压直流母线与低压直流母线,支撑中压直流母线电压;中压级能够构建中压交流母线电压,实现低压级与中压级的互相支撑,并且在离网和并网时均采用电压源输出形式,无需切换控制策略,配合预同步控制实现模式间的无缝切换。RTDS仿真结果表明,系统可采用统一控制策略,无通信实现基于SST的交直流混合配电系统的功率协调与多模式间无缝切换,验证了所提控制策略的有效性与可行性。

The AC/DC hybrid power distribution system based on solid-state transformer(SST)is of great significance for large-scale consumption of renewable energy.Reliable control strategy is the key to ensure stable operation of hybrid power distribution system.In this paper,the coordinated operation control strategy of AC/DC hybrid distribution system based on SST is proposed.The control strategy of“source,storage and load”in the subnet can realize the power balance in the subnet independently.The low-voltage level can maintain the low-voltage AC bus voltage and realize the mutual assistance of AC and DC subnets.The isolation level coupling medium-voltage DC bus and l low-voltage DC bus,support the medium-voltage DC bus voltage.Medium-voltage level can construct medium-voltage AC bus voltage,realize mutual support between low-voltage and medium-voltage levels,and adopt voltage-source output form when off-grid and gridconnected,without switching control strategy,and cooperate with pre-synchronization control to realize seamless switching between modes.RTDS simulation results show that the system can adopt a unified control strategy,and achieve power coordination and seamless switching between multiple modes in the AC/DC hybrid distribution system based on SST without communication,which verifies the effectiveness and feasibility of the proposed control strategy.