The Variable-Frequency Renovation For High-Voltage Motors And Its Safety And Economy Analysis In Coal-fired Power Plant

Energy saving is an important task of plant production management, and has great significance for reducing production costs, increasing economic benefits and enhancing the enterprise viability. High voltage frequency conversion technology as a relatively mature and efficient energy-saving technology has been more and more widely used in thermal power plant, and reaped significant economic and social benefits."The People’s Republic of China Energy Law" proposes explicitly that the development and promotion of frequency control technology for the power plant are an effective measure for reducing station service power consumption rate and realizing higher efficiency with less energy consumption. In the power plant application, the primary air fan and the condensate pump are the important power equipment for the boiler combustion and water supply, which deviate the economy operating condition in power frequency actual operation and when the unit carries partial loads the deviation is farther, particularly the electric motor electrical energy waste is serious. The frequency control may cause the air fan and the water pump to be at the best operating status, thus raising the operating efficiency greatly and achieving the goal of the energy saving.This paper compares the development status of high voltage frequency converter at home and abroad, summarizes the characteristics of foreign frequency conversion technology. Briefly introduces the basic principle of frequency converter control system, combined with the general layout, illustrates the functions of elements. Comprehensive consideration of various factors, such as site environmental requirements of operation, put forward the selecting principle of frequency conversion transformation object, select the two 6kV high voltage motor, a condensate pump motor, the other is a boiler induced draft fan motor. According to their mode of operation, to determine the transformation form, describes the performance of frequency conversion equipment, gives the method of operation in the operation after the revamp and matters needing attention, and the major problems existing in the transformation process and after the transformation are discussed.Before and after the transformation induced motor fan, the energy consumption situation of comparison, data shows that the energy saving effect of frequency conversion transformation. Combined with the practice, summed up the measures improve the operation reliability of inverter. Introduced to improve the management level of some specific methods of frequency converter. The inverter fault classification and basis according to the actual operation situation, summarize the common fault of converter in running, respectively is inverter overheat trip, the inverter load and inverter motherboard failure. Analysis of two inverter fault cases, one is due to cooling system failure, caused by the inverter overheat trip. Another case, boiler draft fan motor frequency transformation, draught fan blade fracture accidents occur, analyzes the fault reason, given solutions and to develop preventive measures. At the end of this thesis, the prospect of the future development trend of high voltage frequency converter.