The invention discloses a
model order reduction method based on a first-order
singular perturbation theory and a grid-connected
system stability
analysis method, and belongs to the field of transient stable operation and control of a novel power
system, and the method comprises the steps: determining a
differential equation set and an
algebraic equation set of a
new energy grid-connected
system; calculating a
time constant of a system state quantity, and dividing the
new energy grid-connected system into a fast subsystem and a slow subsystem based on the
time constant; according to the first-order
singular perturbation theory, after derivation is conducted on the
differential equation set of the fast subsystem, a second-order differential item in the second-order
differential equation set of the fast subsystem is made to be 0, then the second-order differential item is substituted into the differential equation set and the
algebraic equation set of the fast subsystem, and a first-order perturbation
equivalent model algebraic equation is obtained; therefore, the first-order perturbation dynamic state-considered
order reduction model of the
new energy grid-connected system is obtained by combining the differential equation set and the algebraic equation set of the slow subsystem, the dominant dynamic state in the new energy grid-connected system can be effectively identified, and
model order reduction is realized, so that the stability analysis efficiency is improved, and the accuracy is ensured.