CAJ | 학술논문

采用新型LLCL滤波器对单相光伏并网逆变器进行滤波,LLCL滤波器通过在传统LCL滤波器的电容支路中串联一个小电感达到在开关频率处产生串联谐振,相比LCL滤波器能够更大程度地对串联谐振频率处的电流谐波进行衰减,可进一步减小总电感值.分析表明LCL滤波器双电流环控制同样适用于LLCL滤波器,并网电流外环采用带谐波补偿的准比例谐振(PR)控制器能够有效跟踪并网电流指令的同时可对特定次谐波进行补偿,但谐振控制器在谐振频率处存在180°相角跳变,随着谐波补偿的次数增加易导致系统不稳定.在准PR控制器之后增加一个超前校正环节,对谐振频率处进行相位补偿的同时能够提高系统的相位裕量,增强系统稳定性.此外,引入电网电压前馈控制增强系统对电网电压的抗干扰能力.仿真结果表明系统具有较好的稳态性能和抗干扰性能.
채용신형LLCL려파기대단상광복병망역변기진행려파,LLCL려파기통과재전통LCL려파기적전용지로중천련일개소전감체도재개관빈솔처산생천련해진,상비LCL려파기능구경대정도지대천련해진빈솔처적전류해파진행쇠감,가진일보감소총전감치.분석표명LCL려파기쌍전류배공제동양괄용우LLCL려파기,병망전류외배채용대해파보상적준비례해진(PR)공제기능구유효근종병망전류지령적동시가대특정차해파진행보상,단해진공제기재해진빈솔처존재180°상각도변,수착해파보상적차수증가역도치계통불은정.재준PR공제기지후증가일개초전교정배절,대해진빈솔처진행상위보상적동시능구제고계통적상위유량,증강계통은정성.차외,인입전망전압전궤공제증강계통대전망전압적항간우능력.방진결과표명계통구유교호적은태성능화항간우성능.
A new filter, named LLCL, is used for filtering the output current of single-phase PV grid-connected inverter. It is realized by inserting a small inductor in the branch of the capacitor of LCL filter to generate a series resonant circuit at the switching frequency. Compared with LCL filter, LLCL filter can attenuate the series resonant frequency current ripple components much better and can further reduce total inductance value. Dual current loop control for LCL filter also applies to LLCL filter. The quasi PR controller with harmonic compensation in the out loop of grid current can effectively track the grid current instructions and compensate the particular harmonic. But the resonant controllers have a 180° angle jump at the resonant frequency, and with the increasing numbers of harmonic compensation, it can easily make the system instable. Therefore, a leading correction link is added after the quasi PR controller to compensate the phase at the resonant frequency. At the same time, it can improve the phase margin of the system and enhance the system stability. To enhance the grid voltage anti-interference capacity of the system, grid voltage feed forward strategy is utilized. The simulation results show that the system has good steady state performance and the anti-interference performance.