Low-voltage ride-through control method for doubly-fed wind power rotor string resistance based on power optimization

Abstract

The invention discloses a power optimization-based series resistance low-voltage ride-through control method of a doubly-fed wind power rotor. An active power given value of a doubly-fed motor is changed in real time according to feed-forward control of a voltage drop depth of a power grid, the power output of the doubly-fed motor in a low-voltage ride-through period is rapidly and effectively controlled, power balance at two sides of a rotor converter in the low-voltage ride-through period is achieved, a voltage of a DC bus is prevented from rising, current overshoot of a stator and the rotoris prevented, and safe, stable and zero-voltage ride-through running of the system is basically achieved without additionally arranging extra hardware equipment; and with the controllability of the doubly-fed motor in the series resistance low-voltage ride-through period of the rotor, more reactive power supports are provided for the power grid to a great extend under the condition that the system is enabled to be stable and a current of the rotor converter is not over-limited, and rapid recovery of a fault voltage of the power grid is facilitated. The power optimization-based series resistance low-voltage ride-through control method has the beneficial effects that the system cost is reduced, and the power optimization-based series resistance low-voltage ride-through control method has certain engineering practicability.

Description

technical field [0001] The invention relates to the field of electronic technology, in particular to a power optimization-based low-voltage ride-through control method for doubly-fed wind power rotor string resistance. Background technique [0002] Variable-speed constant-frequency doubly-fed wind turbines are currently the most widely commercialized wind turbines. With the increase in installed capacity and their own structural characteristics, modern power regulations require wind turbines to It still has the capability of uninterrupted grid-connected operation for a certain period of time, that is, it has the capability of low voltage ride through (Low Voltage RideThough, LVRT). At present, the LVRT control strategy of doubly-fed induction generator (DFIG) can be divided into three categories: hardware improvement measures, software improvement measures and hardware-software combination comprehensive improvement measures. [0003] In terms of hardware improvement, indust...

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Problems solved by technology

[0006] Based on the above theoretical research results, the common point is how to reduce the excess energy generated by LVRT, that is, how to limit the rotor overvoltage and overcurrent during LVRT to a safe range under the control of additional hardware circuits and software. The passive protection method is not based on fundamentally reducing the input-output energy imbalance brought by LVRT to DFIG from the source

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