DAB储能变换器双闭环模型预测控制与PI补偿控制策略研究

RESEARCH ON DOUBLE CLOSED-LOOP MODEL PREDICTIVE CONTROL AND PI COMPENSATION CONTROL STRATEGY FOR DAB ENERGY STORAGE CONVERTER

针对直流微电网中分布式电源输入输出功率不稳定造成的直流母线电压波动问题,鉴于双有源桥(DAB)储能变换器具有能量双向流动的特点,提出一种基于内模原理的双闭环模型预测控制策略。在分析DAB变换器扩展移相调制原理与特性基础上,重点研究电压外环和电流内环的模型预测控制策略。针对模型预测控制性能依赖电路参数准确度问题,分别从电路主要参数失配对功率传输和直流母线稳压的影响两个角度出发,深入分析模型参数敏感度。最终设置直流母线电压稳态误差灵敏度区,在误差灵敏度区外仅采用双闭环模型预测控制以保证系统的动态响应性能,在误差灵敏度区内采用双闭环模型预测控制和PI补偿控制以消除系统稳态误差。搭建实验平台进行实验验证,结果表明:在系统受到扰动时,DAB储能变换器可实现快速地充放电对系统进行补偿,混合控制策略可快速保持母线电压的稳定,实现系统功率均衡,增强系统抗扰能力。

Aiming at the problem of DC bus voltage fluctuation caused by the instability of input and output power of distributed power supply in DC microgrid,and considering the characteristics of dual active bridge(DAB)energy storage converter with bidirectional energy flow,a dual closed-loop model predictive control strategy based on internal model principle is proposed in this paper.Based on the analysis of extended phase-shifting modulation principle and characteristics of the DAB converter,external voltage closed-loop model predictive control strategy and internal current closed-loop model predictive control strategy are emphatically studied.In order to solve the problem that the performance of model predictive control depends on the accuracy of circuit parameters,the sensitivity of model parameters is analyzed from two aspects:the influence of the mismatch of circuit main parameters on power transmission and DCbus voltage stabilization.Finally,the steady-state error sensitivity area of DC-bus voltage is set.Outside the error sensitivity area,only double closed-loop model predictive control is used to ensure the dynamic response performance of the system.Within the error sensitivity area,double closed-loop model predictive control and PI compensation control is used to eliminate the steady-state error of the system.An experimental platform is built.The experimental results show that when the system is disturbed,the charging and discharging modes of the DAB energy storage converter can achieve smooth switching,and the hybrid control strategy can quickly stabilize the DC-bus voltage,achieve system power balance,and enhance the system anti-interference ability.