An asymmetric fault ride-through method for doubly-fed wind turbines

Abstract

The invention discloses an unsymmetrical fault ride-through method of a double-fed wind generating set. According to the method, a rotor-side convertor control circuit comprises a rotating speed outer ring and a rotor positive and negative sequence current control inner ring, and in order to eliminate the influence of direct-current decrement of a stator flux linkage, a corresponding compensation item is introduced at an outlet of a positive sequence current controller; in order to avoid the overcurrent or overvoltage of the rotor convertor, a novel current amplitude limiting link is designed, and an integral saturation link and an output amplitude limiting link are respectively introduced for the current controller; according to a network-side convertor, actual active power of a rotor is introduced in an outer ring direct-current voltage circuit to balance power on the two sides of a direct-current bus in real time; meanwhile, actual measurement negative sequence network voltage is an inner ring positive sequence current control circuit to eliminate the influence of negative sequence voltage. The defect that an existing control strategy cannot take the influences, on the network-side / rotor-side convertor, of occurrence of the generator terminal negative sequence voltage and the requirement for idle supporting of a power network in the failure period into account at the same time yet is overcome, and therefore the fault ride-through capacity of the double-fed wind generating set is improved.

Description

technical field [0001] The invention relates to the technical field of wind power generator control, and in particular proposes a novel asymmetric fault ride-through method for double-fed wind power generators. Background technique [0002] At present, as the proportion of wind power generation in the power grid is gradually increasing, doubly-fed wind power generators have become the most widely used in wind farms due to their advantages such as relatively small capacity of AC excitation converters, low cost, and variable speed and constant frequency operation. One of the most extensive models. However, since the stator winding of the doubly-fed generator set is directly connected to the grid, the rotor winding is connected to the grid through an excitation converter with a relatively small capacity (not exceeding 30% of the rated capacity), making it very sensitive to grid disturbances, especially under asymmetrical faults. , even if a small unbalanced voltage disturbance...

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Problems solved by technology

[0008] The purpose of the present invention is to provide an asymmetric fault ride-through method for doubly-fed wind power generators, which can overcome the failure of existing control strategies to simultaneously take into account the impact of the negative sequence voltage at the machine terminal on the grid-side / rotor-side converter and the power grid during the fault. Reactive power support requirements, thereby improving the fault ride-through capability of doubly-fed wind turbines

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