With the increasing penetration of new energy sources

the stronger and more diverse external excitation have been introduced into power system in the process of its development towards electrification and cleanliness. To address this issue

stochastic differential equations is firstly adopted as the theoretical framework

two types of stochastic excitation models

that is Gauss and Poisson

are introduced

and algebraic modeling is carried out for the external power ring of photovoltaic power supply machine controlled by virtual synchronous generator (VSG). Secondly

the Milstein-Euler numerical algorithm is applied to numerical solution

and the Matlab simulation tool is used to simulate and analyze the single VSG system as well as the parallel system with four generators

thus evaluating the response characteristics of system under the influence of stochastic perturbations

and then exploring its stochastic stability. Finally

through comparing and analyzing the system response curves

the criterion of mean-square stability and mean-value stability is verified. The simulation results show that the photovoltaics-storage VSG can provide effective inertial support for the system under the influence of stochastic excitation

which significantly enhances the system stability.