Doubly-fed wind generator low voltage ride through control method based on improved Crowbar

Abstract

The invention provides a doubly-fed type wind-power-improved Crowbar circuit which is low in circuit cost, high in reliability, simple in structure and simple in control strategy. The improved Crowbar circuit meets the requirement of an existing Crowbar circuit for protecting a doubly-fed wind generator and overcomes the defect that in the voltage drop process, low voltage ride through can not be achieved through the existing Crowbar circuit. According to a doubly-fed wind generator low voltage ride through control method, the defect that a Crowbar protection circuit on the rotor side can not provide reactive power support for a power grid is mainly overcome by arranging the Crowbar protection circuit on the stator side. The doubly-fed wind generator low voltage ride through control method is mainly characterized in that control is achieved through rotor exciting voltage when the voltage drop amplitude is smaller than the limit value of rotor exciting voltage control; control is achieved through the combined action of the rotor exciting voltage and the Crowbar protection circuit when the voltage drop amplitude is larger than the limit value of rotor exciting voltage control. When the method is applied, the low voltage ride through capacity can be effectively improved under the condition of the wide-range voltage drop, a doubly-fed wind generator system can be kept connected with the power grid all the time, and stability of the wind generator system is improved.

Description

technical field [0001] The invention belongs to the field of wind power generation, in particular to an improved DFIG low-voltage ride-through control of a crowbar circuit. Background technique [0002] In recent years, with the development of wind power generation technology, the installed capacity of wind power generation has been increasing year by year. After the power grid fails and the voltage drops, if the wind power generation units are disconnected, it will bring about transient instability of the power system and may cause Partial or even systemic paralysis. Therefore, the power system puts forward a series of requirements for the operation of wind farms, including the fault ride-through capability of the grid, that is, when the voltage at the grid-connected point of the wind turbine drops, the wind turbine can remain connected to the grid, and even provide a certain amount of reactive power to the grid to support the grid voltage recovery. , until the grid volt...

AI Technical Summary

Problems solved by technology

Since the induction motor will absorb reactive power from the grid during operation, it is not conducive to the recovery of the grid fault, and it will lead to off-grid operation in severe cases, so the generator cannot participate in the system power regulation during the fault process, and cannot meet the reactive power requirements of the grid operation regulations , is unfavorable to the grid voltage stability in the transient process, making it difficult to meet the increasingly stringent wind power grid-connected guidelines

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