摘要
孤岛微电网中广泛使用下垂控制,其在负荷变化后会导致系统稳态频率偏离额定值.而传统集中式二次控制方法存在可靠性低、可拓展性不足等问题.基于分布式协同控制原理,设计了一种频率二次协同控制策略,以克服传统集中式二次控制的缺陷,使系统频率恢复到额定值.考虑到孤岛微电网系统内分布式电源之间通信条件限制和实际过程中数字电路采集时滞等因素造成的控制延时和通信延时,利用盖尔圆盘定理和奈奎斯特稳定判据分析了延时对频率二次协同控制策略稳定性造成的影响,提出一种计算控制延时临界值的方法,判断控制延时影响下的协同控制系统稳定性;针对控制延时对稳定性的影响,改进了频率二次协同控制策略,并给出了改进型协同控制策略的稳定性分析过程和参数设计方法;改进后的策略可以保证系统在更大的控制延时下稳定运行;最后通过Matlab/Simulink搭建了所研究的微电网的仿真模型.仿真结果表明:基于分布式协同控制原理设计的频率二次协同控制策略可以实现孤岛微电网系统的频率恢复;控制延时会影响分布式协同控制系统的稳定性,控制延时超出临界值会造成控制系统失稳.通过改进频率二次协同控制策略,可以提升分布式协同控制系统的稳定裕度,使其在更大的控制延时范围内保证微电网稳定运行.
Primary droop control is widely used in island microgrids.This strategy will cause a steady-state frequency variation between the rated value and actual value when the load changes.Meanwhile,the traditional centralized secondary control of island microgrids has low reliability,insufficient scalability,and other problems.Based on the distributed cooperative control,a frequency secondary cooperative control strategy is designed in this study to overcome the shortcomings of traditional centralized secondary control and eliminate the steady-state frequency variation.Various kinds of delay caused by the acquisition time delay of digital circuits and the limitations of communication conditions among the distributed generations are considered to analyze system stability.The Gerschgorin disk theorem and Nyquist stability criterion were used to analyze the influence of delay on the stability of the frequency secondary cooperative control strategy.A method to judge the stability with delay was proposed by calculating the critical value of control delay.To reduce the influence of delay on the stability of the control strategy,the frequency secondary cooperative control strategy was improved,where the corresponding stability analysis and parameter design method were given.The improved strategy can ensure the operation stability of the system with a larger control delay.Finally,a simulation model of the studied microgrid was established in Matlab/Simulink,and the simulation results demonstrated that the designed frequency secondary cooperative control strategy can realize the frequency recovery in an island microgrid.The control delay can affect the stability of the coordinated control system when it exceeds the critical value.By applying the improved frequency secondary coordinated control strategy,the stability margin of distributed cooperative control system is increased and the stable operation of the microgrid with a larger control delay can be ensured.
作者
李志军
张牟发
张家安
Li Zhijun;Zhang Moufa;Zhang Jia’an(State Key Laboratory of Reliability and Intelligence of Electrical Equipment,Hebei University of Technology,Tianjin 300130,China;Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province,Hebei University of Technology,Tianjin 300130,China;School of Artificial Intelligence,Hebei University of Technology,Tianjin 300130,China)
出处
《天津大学学报（自然科学与工程技术版）》
EI
CAS
CSCD
北大核心
2022年第10期1061-1070,共10页
Journal of Tianjin University：Science and Technology
基金
河北省科技支撑计划资助项目(15212105).
关键词
孤岛微电网
频率二次控制
协同控制
控制延时
islanded microgrid
secondary frequency control
cooperative control
control delay
