适用于直流配电网的直流变压器技术研究

Research on DC Transformer Technology Applied to DC Distribution Network

釆用基于模块化输入串联输出并联拓扑的直流变压器,实现了柔性中压直流配电网和低压直流微电网之间的电压等级变换和功率双向传输。直流变压器的子单元基于LC串联谐振原理,釆用定频不移相控制策略。此外,为了抑制较大的启动冲击电流,提出了一种软启动控制策略:通过脉冲占空比切换的方式控制输入端全桥电路的占空比,从小占空比缓慢切换到额定占空比。设计并生产了一台500kW,±10kV/750V直流变压器,实验结果验证了所提方案的正确性和可行性。

A DC transformer based on modular input-series output-parallel topology is used,which realizes voltage level conversion and power transmission between flexible medium voltage DC distribution network and low voltage DC microgrid.The sub-unit of the DC transformer is based on the LC series resonance principle and adopts a fixed-frequency phase-shifting control strategy.In addition, a soft-start control strategy is proposed to suppress a large start-up inrush current by controlling the duty cycle of the input full-bridge circuit to switch slowly from a small duty cycle to a rated duty cycle by switching the pulse duty cycle.A 500 kW,± 10 kV/750 V DC transformer is designed and produced.The experimental results verify the correctness and feasibility of the proposed scheme.