多逆变器并网系统开关次谐波改进抑制策略

Modified Switching Harmonics Suppression Strategy for Multi-Paralleled Grid-connected Inverters System

多逆变器并网在提升可靠性、满足扩容需求的同时,也给电网注入了开关频次的谐波。为此本文提出一种有源滤波与无源滤波相结合的开关次谐波改进抑制策略,该策略中有源滤波由载波移相策略实现,无源滤波由共用元件型LCL滤波器实现,其中滤波器参数由戴维南等效电路角度重新整定以解决多机并联带来的谐振尖峰偏移问题,使其滤波效果与单机逆变系统保持一致,进而从控制精度和经济成本的角度对共用滤波电感和共用滤波电感电容2种拓扑进行对比分析。本文所述改进抑制策略具有所需LCL滤波元件数目少、物理尺寸小,经济成本低;系统谐振尖峰少等优点。最后通过多逆变器并网实验,全面验证了本文所提策略的有效性和实用性。

Multi-paralleled inverters not only improve the reliability and meet the demand of capacity expansion,butalso inject harmonics at switching frequency into the power grid.Hence,a kind of modified switching harmonics improvement suppression strategy based on the combination of active and passive filtering is proposed in this paper,in which the active filtering is realized by carrier-phase-shift(CPS)strategy,while the passive filtering is achieved by component-sharing LCL filters.Furthermore,the parameters of the filter is reset by Thevenin’s equivalent circuit angle to solve the problem of resonance peak deviation due to multi device parallel operation and make the filtering effect consistent with the single-inverter system,and then from the perspective of the control precision and the economic costs,such two topology as common filtering inductance the common filtering inductive capacitance are compared and analyzed.The modified switching harmonics suppression strategy mentioned in this paper has such advantages assmall number of LCL filter elements,smallphysical size,low economic cost and few system resonance spikes.Finally,the effectiveness and practicability of the proposed strategy are verified by the multi-paralleled inverters experiment.