支撑混合微电网三相不平衡电压与直流脉动电压统一补偿的双向AC/DC变换器研究

The hybrid AC/DC microgrid has become a central issue in the field of flexible power distribution because of its ability to better compatible with a variety of AC and DC power supplies and loads. However, the actual hybrid microgrid with limited capacity tends to be at the end of the distribution network, so three-phase voltage imbalance and DC voltage ripple are common phenomena, which can seriously affect the power quality of the hybrid microgrid. Aiming at the problem of the three-phase voltage imbalance and the DC voltage ripple in the hybrid microgrid, the project proposed to compensate the three-phase unbalanced voltage and DC ripple voltage simultaneously by using the bidirectional AC/DC converter. The project focused on the basic theory and method of AC/DC decoupling method, unified compensation strategy for three-phase unbalanced voltage and DC ripple voltage, and system parameter optimization, and develops an experimental prototype. The proposed AC/DC converter can compensate three-phase AC voltage imbalance and suppress the DC bus voltage ripple while transmitting the power difference of two sub-networks. The successful implementation of the project will provide theoretical and technical support to improve the stable operation level and power supply quality of the hybrid microgrid from the power converter level and its control level. The project can also improve the utilization rate of the bidirectional AC/DC converter and reduce the cost of investment and operation of the power quality regulation device, push forward the development of AC/DC hybrid microgrid, and promote the new energy consumption.

交直流混合微电网因其能够较好地兼容多种交直流电源及负荷成为柔性配电领域的研究热点。然而，实际的混合微电网往往处于配电网末端且自身容量相对较小，三相电压不平衡及直流电压脉动较为普遍，严重影响混合微电网的供电质量。项目针对混合微电网三相电压不平衡及直流电压脉动问题，提出利用交直流母线双向AC/DC变换器统一补偿三相不平衡电压及直流脉动电压的思路。重点研究基于AC/DC变换器的交直流解耦方法、三相不平衡电压与直流脉动电压统一补偿策略及系统参数优化设计的基础理论和方法，并研制实验样机，实现双向AC/DC变换器在传输两子网功率差额的同时，补偿三相交流电压不平衡，并抑制直流母线电压脉动。项目的成功实施将从功率变换器及其控制层面为提高混合微电网供电质量和稳定运行水平提供理论和技术支持，提高双向AC/DC变换器的利用率，降低电能质量调节装置的投资和运行成本，推动交直流混合微电网的发展，促进新能源消纳。

本项目以交直流混合微电网母线接口双向AC/DC变换器为背景，研究了支撑混合微电网交流三相不平衡电压及直流脉动电压统一补偿的母线接口双向AC/DC变换器拓扑结构及控制策略。项目主要研究了三个方面的内容：（1）开展了混合微电网交直流子网耦合特征分析及基于AC/DC变换器的解耦方法的研究，揭示了混合微电网交直流参量交互耦合机理，分别提出基于升压式及降压式的改进型交直流母线接口双向AC/DC变换器拓扑结构；（2）研究了支撑三相不平衡电压与直流脉动电压统一补偿的双向AC/DC变换器控制策略，分别针对基于升压式、降压式的改进型交直流母线接口双向AC/DC变换器，分别建立了双向AC/DC变换器的正、负序等效电路和直流等效电路及2倍频等效电路，并进一步提出了可以实现交流不平衡电压及直流二倍频脉动电压统一补偿的交直流母线接口双向AC/DC变换器控制策略；（3）开展了支撑三相不平衡电压与直流脉动电压统一补偿的双向AC/DC变换器参数优化设计的研究，建立了所提出AC/DC变换器主电路及其控制电路的数学模型，分析了双向AC/DC变换器的动态性能及其稳定性，据此明确影响其运行特性的关键因素及参数选取方法，在此基础上，改进了原有AC/DC变换器样机并开了基于SiC器件的实验平台。经过以上研究表明：交直流脉动功率存在叠加与对消，可利用对消实现交直流脉动功率的自动补偿，小功率脉动功率补偿可以选用降压式补偿拓扑，大功率脉动功率补偿则首选升压式脉动功率补偿拓扑。项目成功实施揭示了交直流二倍频脉动功率的耦合机理，解决了三相不平衡电压与直流脉动电压统一补偿的难题，为提高混合微电网稳定运行水平和供电质量提供了理论和技术支撑。项目执行期间负责人任春光获得了山西省科学技术进步一等奖1项；发表学术论文17篇，其中被SCI检索3篇，EI检索11篇；申请国家发明专利7项，授权国家发明专利2项；培养研究生14名。