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Method for determining threshold value of multi-working-system three-phase induction motor protection system

An induction motor and protection system technology, applied in emergency protection circuit devices, electrical components, etc., can solve the problem that the action value of the protection control system does not allow the motor, etc., and achieve the effect of reducing production costs, realizing utilization, and reducing economic investment.

Active Publication Date: 2019-09-10
HARBIN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

To solve the problem that the action value of the motor's inherent protection control system does not allow the motor to operate under other load modes

Method used

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  • Method for determining threshold value of multi-working-system three-phase induction motor protection system
  • Method for determining threshold value of multi-working-system three-phase induction motor protection system
  • Method for determining threshold value of multi-working-system three-phase induction motor protection system

Examples

Experimental program
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Effect test

Embodiment 1

[0033] Embodiment 1: as Figure 1 to Figure 3 As shown, the motor analyzed in this embodiment is a medium-sized high-voltage three-phase induction motor, and the rated power is 2500kW under the S1 working system. The stator and rotor of the motor adopt air-to-air cooling.

[0034] Step A: Determine the overload capacity of the motor according to the calculation results of the starting characteristics of the motor. When the load torque of the motor described in this embodiment reaches 1.5 times the rated load torque, the motor will stall, resulting in a long-term maintenance of a large starting current in the motor winding, and the motor will not start reliably. Therefore, when the motor is overloaded, the overload capacity of the motor should be calculated first. According to the motor load torque and the flywheel torque of the load system, the electromagnetic torque generated by the electromagnetic induction in the motor is calculated by the formula (1), and the change of t...

Embodiment 2

[0046] Embodiment 2: The difference between this embodiment and Embodiment 1 is that in this embodiment, the motor is a closed three-phase induction motor, and the rated power is 110 kW under the S1 working system.

[0047] According to the collected temperature rise, when the continuous duty three-phase induction motor in this embodiment is driven by 1.1 times, 1.2 times, 1.3 times, 1.4 times and 1.5 times the rated load, the allowable longest short-term overload running time is respectively: 15 minutes, 19 minutes, 25 minutes, 36 minutes and 60 minutes.

[0048] The rated current of the three-phase induction motor in this embodiment is 115A under continuous duty. The calculation shows that when the motor drives 1.1 times, 1.2 times, 1.3 times, 1.4 times and 1.5 times the rated load for short-term operation, the rated current of the motor is: 128.5A, 139A, 150.5A, 161.8A and 173.3A . If the setting of the overload protection is consistent with the rated operating current of...

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Abstract

The invention relates to a method for determining a threshold value of a multi-working-system three-phase induction motor protection system, belongs to the technical field of motor control, and solvesthe problem that an action value of an inherent protection control system of a motor does not allow the motor to operate in other load modes. The method comprises the following steps of calculating electromagnetic torque, and determining the overload capacity of the motor; establishing a dynamic mathematical model of the motor, and calculating the current of a winding; determining the loss in themotor; establishing a fluid-temperature temperature field three-dimensional coupling analysis model of the three-phase induction motor; driving the temperature rise values during different load operation according to the three-phase induction motor under the short-time working system, and determining the short-time working time limit when the motor drives the load to operate in an overload mode;and calculating the starting time and the running current during overload running of the motor, determining the threshold value of the protection action during short-time overload running of the motoraccording to the current value and the setting requirements of overload protection, over-current protection and short circuit protection of the motor, and determining the starting time value of the motor over-current protection required to be hidden. According to the method, the safety guarantee is provided for the operation of the motor in the multi-load mode.

Description

technical field [0001] The invention relates to a method for determining a threshold value of a motor protection system, in particular to a method for determining a threshold value of a protection system when a three-phase induction motor operates under various load duty modes, and belongs to the technical field of motor control. Background technique [0002] The load duty system of the three-phase induction motor is divided into continuous load (S1), short-term load (S2), intermittent cycle load (S3) and intermittent cycle load including starting (S4). In actual production and practical applications, due to work requirements, it is often necessary for a motor to work under different load modes in order to reduce costs and improve production efficiency. [0003] Continuous duty motors and short-time or intermittent duty motors can replace each other, but the action value of the motor's inherent protection and control system does not allow the motor to operate under other loa...

Claims

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Application Information

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IPC IPC(8): H02H7/085
CPCH02H7/0852H02H7/0854H02H7/0855
Inventor 夏云彦温嘉斌杜皓
Owner HARBIN UNIV OF SCI & TECH
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