Models for Calculating Residual Voltage of Induction Motors.

Induction motors are commonly used in driving auxiliary equipment in coal-fired power plants. An external source of power must be connected to the auxiliary system for starting a turbine-generator. After the generator speed is increased to synchronous speed and synchronized with the power system, the power to the generator auxiliary is then supplied from the generator itself. Therefore, circuit switching must be used to transfer the auxiliary power supply from one source to another source. Such switching may possibly cause inrush currents to the motors to be large enough to cause motor damage. The reason for the high inrush currents is that a voltage is being generated by the motors. This voltage is called a residual voltage. The residual voltage is generated by the flux trapped in the rotor windings and by the rotation of the motors after the motors are disconnected from their initial source of power. If the motors are then connected to the second source when the residual voltage is out of phase with the voltage source, large inrush currents will flow in the motor stators.It is important in the design of a station auxiliary to be able to calculate the bus residual voltage of a multi-motor system in order to develop a strategy for operating the station auxiliary.In this thesis, two computer programs based on two approximate motor models are developed to calculate the bus residual voltage of induction motors. The results from these approximate models of a two-motor system are compared to the results obtained from an exact model of an ideal machine. The results obtained from the approximate models compare very well with the results from the model of the exact ideal machine.While it is extremely difficult to write a general computer program for systems with more than two motors based on the exact ideal model, the computer programs based on the approximate models can accommodate any number of induction motors connected to the same bus.

Level thesis:degree_level

Thesis

Year

1981

Author dc:creator

• Dao, Hanh Trong

• Auxiliary system
• Auxiliary power supply
• Turbine-generator
• Synchronous speed

Repository record dc:identifier

https://digitalcommons.library.uab.edu/etd-collection/7141

OAI identifier oai:identifier

oai:digitalcommons.library.uab.edu:etd-collection-8133