摘要
级联运行的电压控制型变换器和电流控制型变换器在离网型微网中广泛应用。针对电压控制型变换器和电流控制型变换器级联运行的电流极限问题,证明输出电流达到极限值会致使系统失稳,严重限制系统输出功率。因系统呈高阶特性,该电流极限的理论值难以直接从阻抗稳定判据推导得到。由此,该文分析并验证阻抗稳定判据和复转矩系数法的一致性,并采用复转矩系数法推导系统有功电流传输极限值,其中包括电压控制型变换器和电流控制型逆变器的级联有功电流极限值以及电压控制型变换器和电流控制型整流器的级联有功电流极限值。然后,分析控制器参数对电流极限值的影响,指出调整控制器参数无法使系统电流极限得到有效突破。由此,为提升系统可传输有功电流,从而提升输出功率,针对电压控制型变换器,考虑其过载限流能力,提出一种改进电压控制方法。最后,通过仿真和实验结果验证研究结果的正确性和所提电压控制方法的有效性。
Cascaded operation of voltage-controlled voltage-source converters(VVSCs)and current-controlled voltage-source converters are widely used in off-grid microgrids.Aiming at the maximum limit of the active current of the VVSC and the current-controlled converter,it has been proved that when the output current of the cascaded system reaches the maximum limit,the system will lose stability restricting the output power of the cascaded system.The theoretical value of the current limit is difficult to be derived from the impedance stability criterion due to the high-order characteristics of the system.Therefore,the consistency between the impedance stability criterion and the complex torque coefficient method has been analyzed and verified in this paper.Based on the complex torque coefficient analysis method,this paper derived the theoretical value of the maximum limit of the active current transmission which includes the current limits of the cascaded VVSC and current-controlled inverter and the cascaded VVSC and current-controlled rectifier.The impacts of controller parameters on the current limits have been analyzed,and it has been proved that adjusting the controller parameters cannot effectively force the output current of the cascaded system to break through the maximum limit.Therefore,considering the overload-current-limiting of the VVSC,an improved voltage control method is proposed,which can significantly improve the active current transmission.Finally,simulation and experimental results verify the correctness of the research results and the effectiveness of the proposed voltage control method.
作者
王凯
原熙博
王晖
张永磊
伍小杰
WANG Kai;YUAN Xibo;WANG Hui;ZHANG Yonglei;WU Xiaojie(School of Electrical Engineering,China University of Mining and Technology,Xuzhou 221116,Jiangsu Province,China;China Electric Power Research Institute,Haidian District,Beijing 100192,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2023年第9期3515-3526,共12页
Proceedings of the CSEE
基金
国家电网有限公司科技项目(19-JS-215)。
关键词
级联系统
极限值
电压控制
逆变器
整流器
cascaded system
maximum limit
voltage control
inverter
rectifier
