The invention provides an aggregation equivalent method for a large-scale
photovoltaic power generation system based on a structure preserving method. The method comprises the steps of establishing adetailed
mathematical model of a two-stage
photovoltaic power generation system, wherein the detailed
mathematical model comprises a
mathematical model of a photovoltaic array, an average model of a preceding-stage Boost circuit, an average model of a backward-stage grid-connected
inverter, an
equivalent model of a
transformer, and mathematical models of a
maximum power point tracking controller and a grid-connected
voltage and current controller; according to an
energy conservation relation among
magnetic field energy,
electric field energy and generalized
potential energy existing in the
photovoltaic power generation system, obtaining a relation between state variables the detailed model and an
equivalent model of the large-scale photovoltaic
power generation system; determining a current and
voltage relation between the detailed model and the
equivalent model according to the same active
power output and
power grid access mode between the detailed model and the equivalent model; andutilizing a capacity weighting method, comparing state equations among different models, and providing an equivalent parameter calculation method of an aggregation equivalent model. The method has the beneficial effects that the aggregation model is enabled to reserve the same circuit and control structure as the original photovoltaic
power generation system on the basis of simplifying the
reduced order model, and meanwhile, an accurate and reliable calculation method is provided for solving equivalent parameters of a photovoltaic array, a Boost circuit, an
inverter, an output filter, a
transformer, a
maximum power point tracking controller and a grid-connected
voltage and current controller in the aggregation equivalent model.