Simulation and experimental investigation of a smooth start system of induction drive
Students Name: Korolchuk Yevhenii Oleksandrovych
Qualification Level: magister
Speciality: Electrical Energetics, Electrical Engineering and Electromechanics
Institute: Institute of Power Engineering and Control Systems
Mode of Study: full
Academic Year: 2022-2023 н.р.
Language of Defence: ukrainian
Abstract: Electronic soft start devices are widely used in various electric drives using asynchronous motors. These devices are used for smooth starting (stopping) of electric motors with different small starting torque of the working machine. Soft start devices provide: smooth acceleration; smooth stop; reduction of starting current; matching the engine torque with the load moment. During start-up, the torque of the electric motor in a fraction of a second often reaches 150-200% of the nominal value, which can lead to failure of the mechanical part of the drive. At the same time, the starting current can be 6-8 times higher than the nominal one, due to which the voltage in the local electrical network drops. A voltage drop can create problems for other network consumers, and if the voltage drop is very large, the motor itself may not start. The use of soft start devices [1,2,3,4] ensures the limitation of the rate of increase and the maximum value of the starting current during the specified time (after installing such a device, the value of the starting current decreases to 3-4 nominal values). In electronic soft-start devices, current limitation is achieved by gradually increasing the voltage on the windings of the electric motor. This allows during start-up to keep the parameters of the electric motor (current, voltage, etc.) within safe limits, which reduces the probability of overheating of the windings and eliminates jerks in the mechanical part of the drive, as well as the probability of hydraulic shocks in pipes and valves at the time of starting and stopping. After all, a correctly selected and adjusted soft start device increases the durability and reliability of the electric motor and its drive. It is best to select a soft start device based on the model made. The first chapter of the explanatory note discusses the advantages of using soft start devices. Special attention is paid to their technical characteristics and switching schemes. Study object ? transient processes in an asynchronous electric drive during start and braking in the case of three-phase voltage regulation using thyristors.. Scope of research ? transient processes in an asynchronous electric drive during start and braking in the case of three-phase voltage regulation using thyristors. Goal of research: to analyze soft-start devices used for soft-starting and stopping of three-phase induction motors with short-circuited rotors. Analyze the advantages of using these devices. The advantages of using voltage regulation in two and three phases are analyzed. Develop a model of an induction motor soft start electric drive in MATLAB Simulink. Conduct research of the developed model of the drive in different operating modes, namely, starting the electric drive with different supply voltages, load moments, fixed and smooth opening angle of thyristors ?. A comparative analysis of the mechanical characteristics obtained by experimental and simulation methods was carried out. In the second section, soft start devices for complex electric drives are considered, in particular, the line of ABB soft start devices for various tasks and areas of application of such devices is analyzed. In the second chapter soft start devices for complex electric drives are considered, in particular, the line of ABB soft start devices for various tasks and areas of application of such devices is analyzed. In the third chapter, the basics of theoretical modeling of asynchronous machines when using the SimPowerSystems package are considered. In the fourth chapter, a step-by-step implementation of the model of a soft-start electric drive with an asynchronous motor is carried out and the capabilities of each new stage of model construction in MATLAB Simulink are shown. In the fifth chapter, the model of the soft-start electric drive with an asynchronous motor was studied, namely, the start of the electric drive with different supply voltages, load moments, fixed and smooth opening angle of thyristors ?, and a comparison of simulation results with experimental results was made. Key words: asynchronous motor, soft start device, automation, electric drive, mathematical model, start, braking. References: 1. T. C. Mallick, S. Dhar and J. Khan, "Artificial neural network based soft-starter for induction motor," 2015 2nd International Conference on Electrical Information and Communication Technologies (EICT), 2015, pp. 228-233. 2. Zhijun Jiang, Xiaoling Huang and Na Lin, "Simulation study of heavy motor soft starter based on discrete variable frequency," 2009 4th International Conference on Computer Science & Education, 2009, pp. 560-563. 3. A. M. Zyuzev, D. P. Stepanyuk and M. V. Bubnov, "Application of passive power filter with induction motor soft starter," 2016 2nd International Conference on Industrial Engineering, Applications and Manufacturing (ICIEAM), 2016, pp. 1-4. 4. M. Rashevskaya, S. Yanchenko and S. Tsyruk, "Assessment of non-stationary harmonic distortion related to adjustable speed induction motor and soft starters," 2018 20th International Symposium on Electrical Apparatus and Technologies (SIELA), 2018, pp. 1-4.