Damping control method for low-frequency oscillation of high-permeability photovoltaic system

The invention discloses a damping control method for low-frequency oscillation of a high-permeability photovoltaic system, the photovoltaic system is a multi-photovoltaic system with four machines and two areas and comprises four synchronous generators and five photovoltaic power stations, and the photovoltaic permeability reaches 50% or above; the two-region photovoltaic system is divided into a region 1 containing a left unit, a region 2 containing a right unit and a region 3 containing a middle tie line and a load. When damping control is carried out, damping control is applied to a photovoltaic inverter, damping control based on wide-area power differential is adopted for an area 1 and an area 2 in the four-machine two-area multi-photovoltaic system, and damping control based on local frequency is adopted for an area 3; a PRONY algorithm is used to analyze a damping control effect, a relative attenuation factor is obtained by subtracting an attenuation factor of a dominant mode under a control strategy fr