Research On The Frequency Conversion System Of Extraction Steam And Power Generation Of Steam Turbine

Nowadays,the active thermal power units often undertake the task of peak shaving,their auxiliary machines work under partial load for a long time,resulting in a long-term low efficiency and high energy consumption operation of auxiliary system,and power consumption rate is relatively high.At the same time,because of the design and selection of thermal power units for security,even if the auxiliary machines operate in the rated load,they also have a larger affluence.Therefore,as the main power consumption equipment of the power plant,the auxiliary machines have greater energy saving and consumption reduction space.At present,the common transformation plan of frequency converter of auxiliary machine can reduce the power consumption rate of the auxiliary power plant.However,due to the harmonic and low frequency heating problems of the inverter,there are frequent accidents on the site.For this reason,a frequency conversion system of extraction steam and power generation of steam turbine was designed.Small turbine takes 75%of load rate the main steam turbine as the design condition,and medium-pressure cylinder exhaust was used as steam source,driving the generator,which can be a variable frequency power supply,instead of frequency converter,thus,driving the motor,to achieve variable speed operation of auxiliary machine.Firstly,for the unit without heat supply,the existing exhaust methods of the system were analyzed,and the key energy efficiency indicators were compared based on the constant flow calculation method.At the same time,the thermal system simulation model of 600MW unit was built by Ebsilon software for cross-validation,and then the reasonable exhaust mode of the scheme proposed in this paper was obtained.Secondly,energy efficiency indicators and economic benefit of frequency converter and the scheme proposed in this paper were quantitatively analyzed;and the influence of parameters on economic benefits such as electricity price,coal price and running hours were calculated respectively.Finally,the frequency converter scheme and the scheme proposed in this paper were compared and analyzed from energy efficiency index,economic benefit,technology and so on.It can be found that the scheme proposed in this paper applied to the variable speed transformation of the auxiliary machine in the field,not only has considerable energy saving potential with frequency converter,but also can increase the profit of power supply and have good economic benefits.Moreover,it can avoid the safety problems caused by the modified scheme caused by frequency converter,and provide a safe and reliable power supply for power plant the auxiliary transmission operation,to ensure efficient and stable operation of thermal power unit,which has a good practical significance.