Mean-tracking model based stochastic economic dispatch for power systems with high penetration of wind power
ENERGY
Authors: Lin, Zhenjia; Chen, Haoyong; Wu, Qiuwei; Li, Weiwei; Li, Mengshi; Ji, Tianyao
Abstract
The random wind power that accounts for a growing proportion in power systems imposes higher challenge on the reliable operation of power system under uncertain circumstances. Since forecasted values of wind speed are accessible to system operators in advance, the corresponding calculated pre-schedule can be regarded as a reference for the stochastic economic dispatch (SED) problem. Existing methods seldom take the pre-schedule into account when determining an optimal dispatch solution, and the resulting dispatch solutions generally differ greatly from the pre-schedule. In this paper, aiming to readjust from the reference schedule as little as possible, the mean-tracking model is proposed for the first time to search for optimal dispatch solutions with the minimal expectation of generation cost and the minimal tracking errors, among which the tracking errors is implemented to each generator unit in terms of minimizing the deviation in generation cost between the trial solution and the pre-schedule. Moreover, the affine decision rule is applied in this paper to distribute the uncertain wind power proportionally to each generator unit. To guarantee the stable operation of power systems, the voltage operating limits are considered to ensure the voltage on each bus remains within the security margins of voltage. Numerical experiments are carried out on a modified IEEE-30 bus system, and simulation results demonstrate the effectiveness of the proposed mean-tracking model for the SED problem. (C) 2020 Elsevier Ltd. All rights reserved.
NuSTAR Discovery of a Compton-thick, Dust-obscured Galaxy: WISE J0825+3002
ASTROPHYSICAL JOURNAL
Authors: Toba, Yoshiki; Yamada, Satoshi; Ueda, Yoshihiro; Ricci, Claudio; Terashima, Yuichi; Nagao, Tohru; Wang, Wei-Hao; Tanimoto, Atsushi; Kawamuro, Taiki
Abstract
We report the discovery of a Compton-thick (CT), dust-obscured galaxy at z.=.0.89, WISE J082501.48+300257.2 (WISE 0825+3002), observed by the Nuclear Spectroscopic Telescope Array. X-ray analysis with the XCLUMPY model revealed that hard X-ray luminosity in the rest-frame 2-10 keV band of WISE 0825+3002 is L-X (2-10 keV) = 4.2(-1.6)(+2.8) x 10(44) erg s(-1) while its hydrogen column density is N-H = 1.0(-0.4)(+0.8) x 10(24) cm(-2), indicating that WISE 0825 +3002 is a mildly CT active galactic nucleus (AGN). We performed spectral energy distribution (SED) fitting with CIGALE to derive its stellar mass, star formation rate, and infrared luminosity. The estimated Eddington ratio based on stellar mass and integration of the best-fit SED of the AGN component is lambda(Edd).=.0.70, which suggests that WISE 0825 +3002 harbors an actively growing black hole behind a large amount of gas and dust. We found that the relationship between the luminosity ratio of X-ray and 6 mu m, and Eddington ratio, follows an empirical relation for AGNs reported by Toba et al.