基于交流恒功率负载特性的交直流混合微电网系统大信号稳定性判据  

Large-signal Stability Criteria of AC/DC Hybrid Microgrid Based on AC Constant Power Loads

作　　者：刘欣博[1] 刘宁[1] 宋晓通 孙晓溪 LIU Xinbo;LIU Ning;SONG Xiaotong;SUN Xiaoxi(School of Electrical and Control Engineering,North China University of Technology,Beijing 100144,China)

机构地区：[1]北方工业大学电气与控制工程学院,北京100144

出　　处：《高电压技术》2021年第10期3441-3451,共11页High Voltage Engineering

基　　金：北京市教委项目(KM201910009010)。

摘　　要：交直流混合微电网系统中,大量电动机负载和变换器负载由受闭环控制的电力电子设备连接交流母线,具有负阻抗特性,可视为交流恒功率负载。这些负载在大扰动情况下类似正反馈,会增强扰动信号,降低系统稳定性,严重时甚至导致整个微电网系统无法正常工作。另一方面,储能单元是系统的惯性环节,合理控制可增强系统稳定性。为了保障并网运行的交直流混合微电网系统大信号稳定性,文中应用混合势函数方法提出储能单元互联变流器稳定控制策略,补偿交流恒功率负载的动态性能。首先,根据abc-dq坐标变换,分别得到交直流混合微电网系统在储能单元充放电状态的简化模型;接着,分别建立系统的混合势函数模型;最后应用第3稳定性定理,分别推导得到储能单元不同工作模式下的大信号稳定性判据。判据给出了滤波参数、交流恒功率负载功率、储能单元充放电功率、储能单元AC/DC变流器电流内环比例环节系数、电压外环比例环节系数的稳定限制条件。实验结果验证了所提大信号稳定性判据的正确性。In the AC/DC hybrid microgrid system,a large number of motor loads and converter loads are connected to the AC bus by closed-loop controlled power electronic devices.These loads have negative impedance characteristics and can be regarded as AC constant power loads,similar to those under large disturbances.Positive feedback will enhance disturbance signals,reduce the stability of the system,and even cause the entire microgrid system to fail to work normally in severe cases.On the other hand,the energy storage unit is the inertial link of the system,and reasonable control can enhance the stability of the system.In order to ensure the large-signal stability of the grid-connected AC/DC hybrid microgrid system,the hybrid potential function method is applied to propose a stable control strategy for the energy storage unit interconnected converter to compensate for the dynamic performance of the AC constant power load.First,according to the abc-dq coordinate transformation,a simplified model of the charging and discharging state of the AC/DC hybrid microgrid system in the energy storage unit is obtained;then,a mixed potential function model of the system is established respectively;finally,the third stability theorem is applied to derive the obtained Large-signal stability criterion under different working modes of energy storage unit.The criterion gives the stability limiting conditions of filter parameters,AC constant power load power,energy storage unit charging and discharging power,energy storage unit AC/DC converter current inner loop proportional link coefficient,and voltage outer loop proportional link coefficient.Experimental results verify the correctness of the proposed large-signal stability criterion.

关 键 词：交流恒功率负载 储能单元AC/DC变流器 混合势函数 大信号稳定性 交直流混合微电网 

分 类 号：TM721.3[电气工程—电力系统及自动化] TM712