Load Commutation Frequency Conversion Technology In Applied Research, High-voltage Motor Starter

High voitage & large capacity synchronous motors are abroad applied in industrys, such as metallurgy,steel,petroleum and chemical.The starting technology of high voitage & large capacity synchronous motor is very important and complex.People has payed a lot of attention to the starting mode for a long time.In general, the starting modes mainly include direction starting,series with reactor starting,variable frequency starting which is the best mode among them. Being started by the rotating converor can effectively reduce the starting current and impact. However, the configuration of rotating converor is complex and needs a lot of devices, it also makes much noise and requires in large amount of maintenance cost. So, the rotating convers are being gradually abandoned.With the continual development of power electronic technology, microelectronics, automatic control theory, computer technology and advanced manufacturing technology, electric drive technology has also experienced a historic revolution that AC speed control substituted DC speed control and computer numerical control technique replaced analog control technique.Alternating current converter has been widely used in starting of high voltage & large capacity synchronous motors.The author works in air system of altitude test facility 0f aviation engine,the air system is consisits of 10 sets of 10kV 12000kW synchronous motors,which are all started by rotating converter.The rotating converor consists of one synchronous motor,two DC generators,one synchronous generator,two DC motors,the capability of output are 0.8HZ～50HZ,200V～10.5kV,4000kW,the frequency and voltage of the adjust are changed by the adjusting of the DC generator excitation current.When starts the 12000kW synchronous motors,the starting current is less than 300A(40% of the rated current 790A).The period of single motor from starting to incorporating is about 8-minuts,the automatization of this system is underdevelopment.The air system in which the author is serving needs to build one air plant.In the air plant,three big compressors are drived by three 10kV 15000kW synchronous motors.So,it is necessary to design one soft starting system,which is used to start three synchronous motors in turn.After analyzing the technology of convertor,we design one soft starting system based on load commutate inverter which is made by SIMENS campany.In the design of the soft starting system,We want to master the principle and the performance of LCI,to accumulate the experience of operating and maintenance,to better the automatization of the air system of ATF.And we want to constitute the criterion of variable frequency starting in order to develop the air system.