Wind power plant flexible direct current grid connection subsynchronous oscillating current detection and suppression method

Abstract

The invention provides a wind power plant flexible direction current grid connection subsynchronous oscillating current detection and suppression method. According to the detection method, through subsynchronous dq rotational coordinate transformation, three-phase currents on the converter valve side of the wind power plant side are transformed to a two-phase dq rotational coordinate system from a three-phase abc stationary coordinate system, and then subsynchronous frequency current components are obtained through filtering of a low-pass filter. The suppression method includes the steps that according to the magnitude of subsynchronous frequency current components output by a wind power plant, a converter on the wind power plant side generates corresponding subsynchronous frequency voltage components on the alternating current side, and then current components which are the same as the subsynchronous frequency current components output by the wind power plant in magnitude and opposite to the subsynchronous frequency current components output by the wind power plant in direction are generated, the subsynchronous frequency current components are offset by the current components, and then subsynchronous oscillating currents are suppressed. According to the suppression method, a control system of a wind power plant unit does not need to be changed, no hardware device needs to be additionally arranged, the amplitude of the subsynchronous frequency current components in alternating currents can be reduced as much as possible within the alternating current voltage allowance fluctuation range, the method is simple, and the calculated quantity is small.

Description

technical field [0001] The present invention relates to a subsynchronous oscillating current detection and suppression method in the field of new energy grid-connected technology, in particular, to a sub-synchronous oscillating current detection and suppression method for a DFIG (double-fed induction motor) wind farm connected to the grid via flexible DC transmission. suppression method. Background technique [0002] Due to the randomness and intermittent nature of wind energy, the strong fluctuation of wind power, and large-scale wind farms are often far away from the load center, the effective access, consumption, and long-distance transmission of large-scale wind power have always been a hot spot that needs to be solved urgently. question. The randomness and strong fluctuation of wind power often bring a series of new technical problems to the active power and frequency control, reactive power compensation and voltage control, safe and stable operation of the grid-connec...

AI Technical Summary

Problems solved by technology

So far, the research on the subsynchronous oscillation of wind farms connected to the grid through flexible DC transmission is basically blank at home and abroad.

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