摘要
并网逆变器是分布式发电系统与电网之间的电能变换接口,然而,随着分布式电源的广泛分布,并网的公共耦合点(point of common coupling,PCC)和电网之间含有较长的输电线路、较多的隔离变压器,导致电网和发电系统之间联络变弱,电网等效阻抗增加,电网呈现弱电网特性.并网逆变器与电网弱联络时,并网逆变器的锁相环(phase-locked loop,PLL)、电流控制环的控制作用会在较广的频域内引入负阻尼,可能导致系统在广域范围内失稳.为了解决这一问题,本文建立了考虑PLL影响的并网逆变器广域阻抗模型,提出了基于阻抗分析的广域稳定性判据,并在此基础上通过在PCC点并联有源阻尼来稳定系统的方法设计了一个广域有源阻尼器,将其并联连接到PCC点,使其在PCC点合成一个并联阻尼电阻以抑制系统产生的谐振.当系统工况发生变化时,通过提取PCC点谐振电压并利用谐波含量限制的方法来自适应调节虚拟电阻值,实现广域范围内镇定系统的效果.最后在MATLAB/Simulink中搭建了并网逆变器等值系统模型,通过时域仿真验证了该广域有源阻尼器的正确性和有效性.仿真结果表明,并网逆变器与电网弱联络时,PLL、电流控制环控制作用等会引起广域谐振稳定性问题,所设计的广域有源阻尼器能有效抑制广域范围内的谐振,且当系统联络突然发生变化时,也可以有效实现系统的广域镇定.
A grid-connected inverter is the power conversion interface between the distributed generation system and the grid.However,with the wide distribution of power,there are long transmission lines and more isolation transformers between the point of common coupling(PCC)and the grid,resulting in a weakened connection between the grid and the generation system,an increase in the equivalent impedance of the grid,and a weakened grid.When the grid-connected inverter is weakly connected to the grid,the phase-locked loop(PLL)and the control of the current control loop of the grid-connected inverter will introduce negative damping in wide areas,which may cause the system to lose stability in wide areas.To solve this problem,a wide-area impedance model of the grid-connected inverter was developed,considering the influence of the PLL,and a wide-area stability criterion based on impedance analysis was proposed.On this basis,a wide-area active damper is designed by paralleling active dampers at the PCC to stabilize the system and connecting them to the PCC to generate a parallel damping resistance at the PCC to dampen the resonances.When the working conditions of the system change,the virtual resistance is adaptively adjusted by extracting the resonant voltage of the PCC and using the method of harmonic content limitation to achieve system stabilization in a wide area.Finally,the equivalent system model of the grid-connected inverter is built in MATLAB/Simulink,and the effectiveness of the wide-area active damper is verified using time-domain simulation.The simulation results show that when the grid-connected inverter is weakly connected to the grid,the PLL and the control of the current control loop will cause wide-area resonance stability problems.The wide-area active damper can effectively suppress resonance over a wide area and stabilize the system when its connection changes suddenly.
作者
李志军
贾杨
张家安
Li Zhijun;Jia Yang;Zhang Jia’an(State Key Laboratory of Reliability and Intelligence of Electrical Equipment,Hebei University of Technology,Tianjin 300130,China;Key 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
2023年第7期755-766,共12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
并网逆变器
锁相环
电流控制环
广域有源阻尼器
广域稳定性
grid-connected inverter
phase-locked loop
current control loop
wide-area active damper
wide-area stability
