Method and device for starting megawatt-level double-fed motor

Abstract

The invention provides a method and device for starting a megawatt-level double-fed motor. A frequency converter at a rotor side of an existing double-fed motor is utilized to control a rotor current (voltage) to generate rotating magnetic fields, so that stator windings which are subjected to short circuit by a stator short-circuit contactor generate an induced current and stator fields, thus the motor generates electromagnetic torques to drive rotors to rotate, thereby realizing zero-speed start of the double-fed motor. In the invention, the frequency converter at the rotor side of the existing double-fed motor is utilized to realize flexible start of the motor, and the stator short-circuit contactor is added. Compared with a rotor series resistance method or stand-by motor dragging method and the like, the method provided by the invention is low in cost, and has no impact on a power grid. Because only one stator short-circuit contactor is added, the system structure is simple, the processes of motor startup, synchronization and speed adjustment are simple without the impact cohesion, and are automatically and completely controlled by a converter, thus the complete automation is realized and the reliability is high.

Description

technical field [0001] The invention relates to a method and device for starting a motor, in particular to a method and device for starting a doubly-fed motor in a full-power test platform of a megawatt-class doubly-fed wind power generating set, which is mainly used for starting a doubly-fed motor in a laboratory environment The motor is used for converter and generator power tests, and it can also be used for the start-up of fan and water pump type wound motors equipped with rotor-side converter speed control devices. technical background [0002] Megawatt double-fed (wound rotor) motors have disadvantages such as large instantaneous absorbed power, high instantaneous voltage and large current of the rotor when the rated voltage is suddenly added at zero speed. At present, the rotor series resistance or the low-power auxiliary motor is generally used. way to start. However, the rotor series resistor method still has a certain impact on the power grid and the motor, and re...

AI Technical Summary

Problems solved by technology

[0002] Megawatt double-fed (wound rotor) motors have disadvantages such as large instantaneous absorbed power, high instantaneous voltage and large current of the rotor when the rated voltage is suddenly added at zero speed. At present, the rotor series resistance or the low-power auxiliary motor is generally used. way to start

However, the rotor series resistor method still has a certain impact on the grid and the motor, and requires high-power resistors, which increases the system cost

The way of driving by a small-power auxiliary motor is only suitable for working conditions such as the full-power test platform of a megawatt-scale doubly-fed wind turbine, which does not increase with the increase in speed, and requires a small-power motor and supporting auxiliary frequency conversion. Inverter and transmission equipment, high system cost

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