Study On Measurement And Control System For Starting Characteristic Of Large Blower

Large blower is a kind of important production equipment, and is widely used in industrial department such as metallurgical industry, electric power industry, mining industry, chemical industry, and so on. Its running relates to directly business enterprise's normal production. However, in the field starting process, large blower is often started hard, or fails to be started, or even the motor is burnout, influencing the security of enterprise's production and causing large economic loss. To solve this actual problem, by analyzing the large blower's practical run and environment condition, this paper presents an effective method, which can measure the large blower's starting characteristic accurately, and explores the key techniques of the method's engineering practice. The paper's major work, results and conclusions as follows:The working principle and working system structure of large blower are studied, and the starting problem of blower is analyzed. The precision and application shortage of the conventional methods of starting characteristic measurement is pointed out. By using the power mechanics technology of electric power driving system, this paper analyzes the large blower's working system, builds its running mathematics model. By studying the energy exchange mechanism among power supply, driving motor and large blower, a novel indirect measurement method of large blower's starting characteristic based on measuring the electrical parameters and speed of the blower's drive motor is presented;The theory of power measurement and torque measurement of motor are studied. The shortage of conventional power measurement with unbalance three-phase voltages and harmonics is analyzed. This paper presents to adopt a novel power detection method based on three-phase instantaneous reactive power theory, and the revolving transformation of coordinate is used to measure the driving torque resulted from the positive sequence power and the braking torque resulted from the negative sequence power. The impact of the three-phase unbalance voltages and the three-phase unbalance winding of the motor is eliminated. The theory analysis and simulation show that this detection method can measure the fundamental positive and negative sequence power accurately. Meanwhile, in order to ensure the security of blower's working system and the normal work of measurement and control system for large blower starting characteristic, by analyzing the causes and forms of driving motor's working trouble, this paper studies the motor concrete protections and their matching relation;According to the engineering and practical design ideology, the hardware structure of the system is designed and the intelligent measurement and control mode based on digital signal processor (DSP) is developed. The related measurement algorithm program and protection algorithm program are programmed to finish the gather and calculation of measured parameters and the control signal output, realizing the large blower's starting characteristic measurement and driving motor's real-time protection;Adopting precise test power to simulate the voltages and currents of driving motor with ideal condition and unbalance three-phase circuits and harmonics, the hardware device of measurement and control system is experimented to measure the fundamental positive and negative sequence currents and to protect the driving motor. The results of experiment show that the designed system can realize blower's starting characteristic measurement and driving motor's protection. The useful explore and trial of automatic measurement for large blower's starting characteristic is made, which has engineering significance.