Equivalent inertia analysis method and system for a direct drive wind turbine

Abstract

The invention discloses an equivalent inertia analysis method and system for a direct-drive wind turbine, and relates to the technical field of electric power systems. The method includes: applying to the wind power system the checking fault of the power grid expected fault concentration, so that the wind turbine is in the low-voltage ride-through state; acquiring the grid parameters of the wind power grid-connected point in the wind power system, and performing Parker transformation on the grid parameters; calculating the low-voltage ride-through time The reactive current value that needs to be injected into the grid for wind turbine support voltage recovery; the active power of the converter is obtained according to the grid parameters, and the active power limit value of the converter is obtained according to the active current limit value; according to the actual value of the active power on the grid side, The equivalent inertia constant of the wind turbine is obtained from the magnitude relationship between the limit value of the active power of the converter and the change value of the active power controlled by the virtual inertia. The invention can improve the frequency stability control level of the grid-connected system including wind power by accurately evaluating the equivalent inertia of the direct-drive wind power through the virtual inertia control considering the low voltage ride-through.

Description

technical field [0001] The invention relates to the technical field of power systems, in particular to an equivalent inertia analysis method and system for a direct-drive wind turbine. Background technique [0002] With the continuous development of wind power technology, the proportion of wind power generation in the power system is increasing. The maximum power tracking control adopted by conventional direct-drive wind turbines makes the kinetic energy stored in the rotor relatively decoupled from the output electromagnetic power, and cannot respond to The frequency change of the power grid cannot provide frequency support for the power grid. When replacing the system synchronous machine, the equivalent inertia of the system will be reduced. However, by using additional virtual inertia control, the direct-drive wind turbine can respond to the frequency change of the grid and participate in the inertia response of the system. [0003] However, the voltage drop at the grid ...

AI Technical Summary

Problems solved by technology

[0003] However, the voltage drop of the wind power grid-connected point caused by the grid failure will cause a large number of wind turbines to enter the low voltage ride-through state. The wind turbines need to inject reactive current into the grid to support the voltage recovery, which will limit the active output of the wind turbines and affect the virtual inertia of wind power. Control the frequency support of the participating systems, which reduces the equivalent inertia of the system and reduces the frequency stability of the wind power grid-connected system

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