Test method of low voltage ride-through capability of frequency converter based on magnetic powder brake

Abstract

The invention discloses a test method of the low voltage ride-through capability of a frequency converter based on a magnetic powder brake. The magnetic powder brake is employed as the simulation load of a coal feeder motor and a powder feeder motor, the loads carried by the coal feeder motor and the powder feeder motor are constant-torque loads, the output brake torque of the magnetic powder brake and field current are in a good linear relation and are irrelevant to the rotating speed or the slip, and the constant torque characteristic is represented in the specific field current. The magnetic powder brake is employed as the simulation load of the coal feeder motor and the powder feeder motor so that the low voltage ride-through capability of the frequency converter in the similar practical operation condition can be tested.

Description

technical field [0001] The invention relates to a method for testing the low-voltage ride-through capability of a frequency converter based on a magnetic powder brake. Background technique [0002] The so-called low-voltage ride-through capability of the inverter refers to the ability to reliably supply power when the external fault or disturbance of the inverter and the power supply object equipment causes a transient, dynamic or long-term power input line voltage to drop to the specified low-voltage ride-through area, ensuring power supply safe operation of the object. At present, thermal power plants are equipped with a large number of auxiliary machines and are often in low-load and variable-load operation states. By installing frequency conversion speed control systems on auxiliary machines, energy-saving benefits can be effectively improved. However, due to the heavy load of low-voltage auxiliary machines such as coal feeders and powder feeders, the "instantaneous sto...

AI Technical Summary

Problems solved by technology

This test work may cause the frequency converter to be blocked and shut down. Generally, it is carried out during the shutdown period of the unit. During the shutdown period, it is difficult for the motors of the coal feeder and powder feeder to operate with actual loads. The current practice is to let the motors of the coal feeder and powder feeder run empty Load operation, that is, the motor is idling or only runs with the belt, and the test results of its low voltage ride-through capability only reflect the results of no-load operation, and cannot reflect the actual situation of the unit in actual operation.

Especially after the transformation, if the low voltage ride through capability test is carried out, if only the no-load running motor is used as the load, the test results are difficult to guarantee the low voltage ride through capability of the unit during normal operation

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