Dual-feeding motor system having protecting device and protecting method thereof

Abstract

The invention discloses a doubly fed generator system with a protector, as well as a method used for protecting the system. The doubly fed generator system with the protector comprises a doubly fed induction generator (100), a rotor side converter (130), an intermediate DC side converter (110), a grid side converter (120) and a bypass protecting circuit (200), wherein the bypass protecting circuit (200) comprises current limiting resistors (R1, R2 and R3) and thyristors (Q1, Q2, Q3, Q4, Q5 and Q6), the thyristors are divided into three groups, each group comprises two thyristors reversely connected in parallel, and is connected with one current limiting resistor in series, and the three groups of thyristors are connected into a star shape; when the voltage of the intermediate DC side converter (110) exceeds the set threshold U2, the thyristors (Q1, Q2, Q3, Q4, Q5 and Q6) are triggered to be conducted. The invention has the advantages of low cost, simple control and stronger fault ride-through capacity.

Description

technical field [0001] The invention relates to a doubly-fed generator system and its protection method, in particular to a doubly-fed generator system with a protection device and its protection method when a grid fault occurs. Background technique [0002] Under grid failure, a large number of generators (such as: wind turbines) disconnected from the grid will cause power loss in the grid and aggravate the collapse of the grid. In order to meet the safety requirements of the power grid, it is required that the generator system (such as: a wind turbine generator system) must have the fault ride-through capability of uninterrupted operation in the case of a grid fault. [0003] Existing doubly-fed generator systems include doubly-fed induction generators (DFIG) and back-to-back converters. The stator winding of a doubly-fed induction generator (DFIG) is generally connected to the grid through a grid-tie switch to a transformer, and the rotor winding is connected to a back-t...

AI Technical Summary

Problems solved by technology

However, the selected electronic switch in this scheme is controlled by pulse width modulation and is actively turned off. Due to the weak overload capacity of the active switch-off electronic switch, it usually requires multiple tubes to be connected in parallel, and current sharing will occur when the rotor winding is short-circuited. and overcurrent problems

For severe grid faults, this solution will cause the generator stator to go off-grid due to rotor overvoltage, so the cost of this solution is high, the control is complicated, and the fault ride-through capability is weak

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