Low-voltage ride through control method and device for doubly-fed wind power generating system

Abstract

The invention discloses a low-voltage ride through control method and a low-voltage ride through control device for a doubly-fed wind power generating system. The device comprises a reversible power converter, a motor controller, a signal detection circuit and a crowbar protection circuit. The crowbar protection circuit consists of a three-phase uncontrolled bridge rectifier, a primary release circuit and a secondary release circuit. When a power grid has a low-voltage failure, the reversible power converter stops working, the primary and secondary release circuits in the crowbar protection circuit are switched on at the same time and work in parallel to rapidly release transient impact current in a rotor winding of a doubly-fed motor; when the current of a rotor attenuated to a rated value, the secondary release circuit stops working, and the primary release circuit is still switched on to release the transient current in the rotor wining; and after the low-voltage failure of the power grid is eliminated to recover the voltage of the power grid, the reversible power converter restarts working, and the crowbar protection circuit completely stops working. By the method and the device, high ride through capability and good effects are ensured, the time of a transient process for low-voltage ride through can be shortened, the voltage recovery of the power grid can be accelerated and secondary over-current can be effectively prevented.

Description

technical field [0001] The invention relates to the field of wind power generation, in particular to a low-voltage ride-through control method and device for a doubly-fed wind power generation system. 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 recove...

AI Technical Summary

Problems solved by technology

[0004] The current IGBT-based crowbar protection circuit used in low-voltage ride-through has defects: (1) the capacity is small and cannot adapt to large-capacity double-fed wind power generation systems, (2) it is easy to cause DC bus voltage overvoltage and secondary overcurrent, etc. question

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