Photovoltaic virtual synchronous unit damping characteristic test method based on power-frequency transfer function

The invention provides a photovoltaic virtual synchronous unit damping characteristic test method based on a power-frequency transfer function and relates to the technical field of photovoltaic powergeneration grid-connected auxiliary equipment. A first-order inertia link response characteristic can be obtained by making a step for an input signal delta P and observing the response of an output signal, and furthermore, single-machine inertia and damping coefficientsare calculated. The method specifically comprises the steps of recording AC side voltage and current data of a virtual synchronous unit through test equipment, calculating active power and a voltage-frequency curve, calculating to obtain single-machine inertia and a damping coefficient under such working condition according tothe voltage-frequency response curve, repeatedly testing the single-machine inertia and damping coefficients under various working conditions, and averaging the single-machine inertia and the dampingcoefficients. The test meth