Voltage control strategy of grid forming parallel inverters based on virtual oscillator control under islanded mode
Because of the coupling of control parameters,the existing grid forming parallel inverters based on virtual oscillator control have the problems of high harmonic content of bus voltage and significant vol-tage fluctuation impacted by load,which reduces the power supply quality under islanded mode.Therefore,according to the different requirements of voltage establishment stage and voltage maintenance stage,the harmonic suppression method is proposed by optimizing the parameters of virtual oscillator.Based on the output characteristics of inverter,a voltage regulation method is proposed.A voltage control strategy is formed by associating harmonic suppression and voltage regulation through a parametric rolling optimization method.In addition,a small signal state space model of virtual oscillator control-based parallel inverter sys-tem with resistive-inductive loads is established.The results show that,under the proposed voltage control strategy,the bus voltage total harmonic distortion of the parallel system can be reduced to 1.13%,and the bus voltage can be quickly restored to stability when the load is switched.The dominant eigenvalues of the system state matrix are all located in the left half complex plane under three working conditions of light load,rated load and heavy load,indicating the asymptotically stability of system.
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维普
