Bian S.,Shanghai Minghua Electrical Power Technology & Engineering Co. |
Pan L.,Huaihu Coal and Power Co. |
Huo Y.,Huaihu Coal and Power Co.
Dongli Gongcheng Xuebao/Journal of Chinese Society of Power Engineering | Year: 2014
A number of models were built up respectively for on-line monitoring of tube wall temperatures at high-temperature heating surfaces, oxide scale growth, on-line calculation of scale stress and for exfoliation evaluation of the oxide scales. Based on these models, a management system for steam-side oxide scale on high-temperature heating surfaces of boiler was developed and applied to a 600 MW supercritical power boiler. Results show that with the oxide scale management system, thermal deviation can be reduced along flue duct width direction, which will result in reduced in-furnace tube wall temperature of deviated panels, and lowered growth rate of oxide scales; deposition and exfoliation of oxide scales can also be prevented by on-line monitoring of corresponding temperatures and scale stress. © 2014, Editorial Department of Chinese Society of Power Engineering. All right reserved. Source
Shen C.,Shanghai Minghua Electrical Power Technology & Engineering Co. |
Gui Y.,Shanghai Minghua Electrical Power Technology & Engineering Co. |
Cheng J.,Shanghai Minghua Electrical Power Technology & Engineering Co. |
Wang N.,Shanghai Minghua Electrical Power Technology & Engineering Co.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2015
To solve the common problem that the traditional primary frequency regulation control strategy is not able to achieve sufficient primary frequency regulation capability and is easy to cause intense oscillation of frequency modulation devices, a primary frequency regulation control strategy with “fast-moving and delayed-returning” or “fast-moving and slow-returning” technology is proposed based on the judging of frequency difference and the blocking of inverse regulating action. The proposed strategy can provide more frequency regulation electric power by blocking or limiting the inverse frequency regulation effect of power grid, which makes the primary frequency regulation better coordinated with the secondary frequency regulation, thus improving both the elimination speed of power grid frequency difference and the quality of power grid frequency control. Furthermore, a counter-measure against power overcorrection or power jumping problems in practical applications is proposed by setting appropriate control parameters such as the frequency regulation gain. In the end, in order to prove the effectiveness of the proposed strategy, both the traditional primary frequency regulation control strategy and the proposed strategy are applied to two coal-fired power generating units. Experimental results show that the proposed strategy can provide more frequency regulation electricity for power grid as well as reduce generator wear caused by frequency regulation, thus benefiting both power grid and generator units. ©, 2015, Automation of Electric Power Systems Press. All right reserved. Source
Shuchao G.,Shanghai Minghua Electrical Power Technology & Engineering Co. |
Yuping D.,Dalian University of Technology |
Peng D.,Shanghai Minghua Electrical Power Technology & Engineering Co. |
Song W.,Shanghai Minghua Electrical Power Technology & Engineering Co. |
And 2 more authors.
Journal of Electronic Materials | Year: 2015
The microwave-absorption properties and microstructures of Fe-Ni and Fe-Ni-Cr alloys prepared by mechanical alloying were investigated in the frequency range 2–18 GHz. Other properties were studied by scanning electron microscopy, x-ray diffractometry, vibrating sample magnetometry, and transmission line theory. Dependence of reflection loss (RL), electromagnetic properties (permeability μ and permittivity ε), magnetic and dielectric loss tangent, impedance matching, and absorber thickness (d) on milling time is discussed. The alloy powders had excellent microwave-absorption properties in the frequency range 7 to 14 GHz. The minimum RL, the frequency at which the RL is minimum, and the bandwidth (RL < −10 dB) all depend on milling time and d. Introduction of Cr affected the RL of the powders, especially the minimum RL of −19.8 dB at 7.2 GHz for Fe-Ni-Cr powder milled for 90 h (compared with −22 dB at 9.9 GHz for Fe-Ni powder milled for the same time), suggesting that the Fe-Ni-Cr alloy could be a promising candidate as a microwave-absorbing filler at low frequencies. This may help broaden the range of microwave-absorbing materials. © 2015, The Minerals, Metals & Materials Society. Source