Tong X.,Hunan First Normal University |
Luo X.,Hunan Electrical Power Research Institute |
Yang H.,Changsha University |
Zhang L.,Hunan Xiangdian Boiler and Pressure Vessel Test Center .
International Transactions on Electrical Energy Systems | Year: 2017
In this paper, we study the risk-limiting dispatch (RLD) of power system in the case that the distribution information of random variable is ambiguous. Under an ellipsoidal moment uncertainty of the mean and the covariance matrix, we develop the distributionally robust optimization approach to set up a new RLD model, named robust RLD (RRLD for short). The RRLD considers simultaneously the risk of unsafe operation limit by conditional Value-at-Risk management. We further convert the RRLD model into a solvable convex optimization for a special case that the operation constraint is addressed on the overloading transmission current. The new RRLD model is a development and generalization of the traditionary economic dispatch and the RLD approach. Meanwhile, our research extends the distributionally robust optimization application in portfolio problems to a security economic operation of power system. The IEEE-14 and IEEE-30 bus system are chosen as numerical test systems. Preliminary numerical examples show the validity of the model and its reformulation. © 2017 John Wiley & Sons, Ltd.
Long H.-G.,Hunan Xiangdian Boiler and Pressure Vessel Test Center Ltd |
Long H.-G.,Hunan Electric Power Company |
Xie G.-S.,Hunan Xiangdian Boiler and Pressure Vessel Test Center Ltd |
Xie G.-S.,Hunan Electric Power Company |
And 3 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2013
Oxidation mechanism and characterization of steam-side oxidation scale formed on the internal surface of super-heater and re-heater tubes made of TP347H austenitic stainless steel removed from boiler of some power plant were investigated by metallurgic inspection, scanning electron microscope-energy dispersive X-ray (SEM-EDX) analysis and X-ray diffraction. The results show that the steam-side oxidation scale normally consists of three layers, the inner layer is heterosphere oxides layer consisting of (Cr, Fe)2O4 and NiO, the middle layer is loose and porous and identified as Fe3O4 with the coarse columnar crystal microstructure and the outer layer is compact but very thin and identified as Fe2O3 with the lower tine equiaxed crystal microstructure. Some fine equiaxed crystal oxides are observed in the interface of the inner and middle layers, which lowers the binding strength of the interface and the exfoliatation of scales more easier occurs. The flakes exfoliated from the steam-side oxidation scale of TP347H steel tubes are mainly made up of the outer layer and middle layer of the oxidation scale.
Xie G.,Hunan Xiangdian Boiler and Pressure Vessel Test Center Co. |
Xie G.,Hunan Electric Power Company |
Long H.,Hunan Xiangdian Boiler and Pressure Vessel Test Center Co. |
Long H.,Hunan Electric Power Company |
And 5 more authors.
Dongli Gongcheng Xuebao/Journal of Chinese Society of Power Engineering | Year: 2013
Steam-side oxidation scales formed on inner surface of super-heater and re-heater tubes made of 10CrMo910 steel in a power plant were investigated by metallurgic inspection, scanning electron microscope-energy dispersive X-ray (SEM-EDX) spectrometer, and X-ray diffraction analysis. Results show that the steam-side oxidation scale normally consists of two layers: the inner layer is a heterogeneous oxidation film rich in Cr and pores, whereas the outer layer contains porous and fine particles identified as Fe3O4 and Fe2O3; internal oxidation exists at the interface between base metal and inner layer, resulting in compact bonding of the interface; the oxidation at interface between inner and outer layer is not obvious, where firm adhesion is formed and a small number of oxide particles are left after decomposition; both the inner and outer oxidation layer are composed of nanometer or micro particles, and the thermal stress caused by mismatch of thermal expansion coefficients are relaxed by pores lying in the oxidation particles. The steam-side oxidation film of 10CrMo910 steel tube is difficult to peel, and its growing thickness may cause the heating surface steel tube to work at overheating temperatures.