دانلود مقاله ترجمه شده براورد الگوی فلش ولتاژ جهت راه اندازی موتور با ولتاژ بالا – مجله IEEE

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Abstract

High voltage and great power motors’ starting cause big impacts to power grids and introduce voltage sags. In severe cases, it will affect the normal operation of other devices. Voltage sags have been the most prominent problems of the power quality, and both sides of the power supply pay close attention to them. This paper mainly focuses on the starting process of the high voltage and great power induction motors which are widely used in industries. It’s key to model the motor starting process, including selections of the equivalent circuit of motors with different structures, collections and checking of stators and rotors’ impedance. Normally, lacking the delivery test materials, they should be obtained by experience. The key point to improve the simulation accuracy is to model mathematical expressions of motor stators and rotors’ impedance in the starting process to get more accurate curve of motors’ electromagnetic torque, including the collection and evaluation of motors’ rotation inertia. It is directly related to the duration of the starting process. The collection and evaluation of load torque curve are related to acceleration torques. Finally, it determines the duration of the starting process. This paper also introduces techniques to reduce the starting current, to reduce the impact to the power grid, to control voltage sags levels in limits. The research has been successfully used in power quality evaluation for the integration of Shanghai Qingcaosha Raw Water Project, Shanghai Zizhuyuan Refrigeration Units project.

 Introduction

These days, voltage sag becomes the most outstanding problem of the power quality when the number of the power quality sensitive equipments increases and the request of power quality is improved. According to the research of EU power department, voltage sag shared above 80% of the consumer complains about the power quality. High voltage and great power motors fully start, it need take 5-8 times rating current from the power grid, when this current passes the system impedance, it will cause voltage sag on the supplying bus and the related bus. Voltage sag on the supplying bus results in two serious problems: first it will break the working condition of other running equipments, specially the power quality sensitive equipments. For example, when the voltage is below 80% rating voltage, the servers of the computer network will stop and the client computer will lose data. When the voltage is below 50% rating voltage, most contactor will disconnected, PLC controllers will stop working. Second, the receiving side of the motor cannot guarantee the starting torque which causes the motor cannot start finally.

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