不平衡电网下隔离型固态变压器非线性一体化控制  

Nonlinear Integrated Control of Isolated Solid State Transformer Under Unbalanced Grid

作　　者：张国澎[1] 李子汉 王浩 杨明[1] ZHANG Guopeng;LI Zihan;WANG Hao;YANG Ming(School of Electrical Engineering and Automation,Henan Polytechnic University,Jiaozuo 454003,Henan Province,China)

机构地区：[1]河南理工大学电气工程与自动化学院,河南省焦作市454003

出　　处：《电网技术》2022年第6期2317-2326,共10页Power System Technology

基　　金：国家自然科学基金项目(U1804143);河南省科技攻关项目(202102210294);河南省高校基本科研业务费专项资金资助(NSFRF210423)。

摘　　要：由多个功率变换级构成隔离型固态变压器(solid state transformer,SST)是一种非线性、强耦合系统。由于前后2级功率传递的响应不同,系统整体的动态性能难以保证。不平衡的三相电网环境又会进一步加剧此类变流器控制难度,SST2级间电容承受的电压应力与交流侧的并网电流质量更加难以保障,影响着SST的运行安全与适用性。为此,根据SST前后级的非线性特性,建立三相电网不平衡条件下SST一体化仿射非线性模型。在此基础上,采用输入-输出精确反馈线性化的方法,实现前级电流环、前后级级间电压与SST直流侧电压的解耦,加强了前后2级功率传递的一致性,保障了SST交流侧并网电流的质量。为进一步提高系统整体的动态性能,将解耦的线性系统与积分滑模控制器结合,改善了系统对参数摄动的鲁棒性。仿真和实验结果验证了以上方法的正确性与有效性。The isolated AC-DC solid-state transformer(SST) usually consists of multiple converter stages,a nonlinear and strong coupling system.Without an efficient control strategy,the different power responses of the two converter stages lead to the poor dynamic performance of the SST.The unbalanced power grid makes the control of the converters more difficult,resulting in the voltage stress borne by the two-stage capacitor of SST and the grid connected current quality on the AC side not to be ensured,which affects the operation safety and applicability of SST.Therefore,An affine nonlinear model of SST integration under the unbalanced three-phase power grid is established.The integrated decoupling method of the exact feedback linearization is proposed to control the AC-grid current in the front stage,the capacitor voltage between the two converter stages,and the DC-grid voltage.This method enhances the consistency of the power transfer between the two converter stages,and guarantees the quality of the grid connected current at the AC side of SST.Furthermore,the integral sliding mode controllers are adopted for controlling the currents and voltages of the SST,achieving better dynamic performance and robustness.Simulation and experimental results verify the correctness and effectiveness of the above method.

关 键 词：固态变压器 不平衡电网 前后级 精确反馈线性化 滑模控制 

分 类 号：TM721[电气工程—电力系统及自动化]