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3. A Mixed-Integer SDP Solution Approach to Distributionally Robust Unit Commitment with Second Order Moment Constraints

Author

Zheng, Xiaodong, Chen, Haoyong, Xu, Yan, Li, Zhengmao, Lin, Zhenjia, and Liang, Zipeng

Subjects
Mathematics - Optimization and Control, Electrical Engineering and Systems Science - Systems and Control
Abstract

A power system unit commitment (UC) problem considering uncertainties of renewable energy sources is investigated in this paper, through a distributionally robust optimization approach. We assume that the first and second order moments of stochastic parameters can be inferred from historical data, and then employed to model the set of probability distributions. The resulting problem is a two-stage distributionally robust unit commitment with second order moment constraints, and we show that it can be recast as a mixed-integer semidefinite programming (MI-SDP) with finite constraints. The solution algorithm of the problem comprises solving a series of relaxed MI-SDPs and a subroutine of feasibility checking and vertex generation. Based on the verification of strong duality of the semidefinite programming (SDP) problems, we propose a cutting plane algorithm for solving the MI-SDPs; we also introduce a SDP relaxation for the feasibility checking problem, which is an intractable biconvex optimization. Experimental results on a IEEE 6-bus system are presented, showing that without any tunings of parameters, the real-time operation cost of distributionally robust UC method outperforms those of deterministic UC and two-stage robust UC methods in general, and our method also enjoys higher reliability of dispatch operation.

Published
2019
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4. A Global Solution Method for Decentralized Multi-Area SCUC and Savings Allocation Based on MILP Value Functions

Author

Zheng, Xiaodong, Chen, Haoyong, Xu, Yan, Shen, Feifan, and Liang, Zipeng

Subjects
Electrical Engineering and Systems Science - Systems and Control
Abstract

To address the issue that Lagrangian dual function based algorithms cannot guarantee convergence and global optimality for decentralized multi-area security constrained unit commitment (M-SCUC) problems, a novel decomposition and coordination method using MILP (mixed integer linear programming) value functions is proposed in this paper. Each regional system operator sets the tie-line power injections as variational parameters in its regional SCUC model, and utilizes a finite algorithm to generate a MILP value function, which returns the optimal generation cost for any given interchange scheduling. With the value functions available from all system operators, theoretically, a coordinator is able to derive a globally optimal interchange scheduling. Since power exchanges may alter the financial position of each area considerably from what it would have been via scheduling independently, we then propose a fair savings allocation method using the values functions derived above and the Shapley value in cooperative game theory. Numerical experiments on a two-area 12-bus system and a three-area 457-bus system are carried out. The validness of the value functions based method is verified for the decentralized M-SCUC problems. The outcome of savings allocation is compared with that of the locational marginal cost based method., Comment: 8 pages, 7 figures

Published
2019
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30. The OsAGO2–OsNAC300–OsNAP module regulates leaf senescence in rice.

Author

Zheng, Shaoyan, Chen, Junyu, He, Ying, Lu, Jingqin, Chen, Hong, Liang, Zipeng, Zhang, Junqi, Liu, Zhenlan, Li, Jing, and Zhuang, Chuxiong

Abstract

ABSTRACT Leaves play a crucial role in the growth and development of rice (Oryza sativa) as sites for the production of photosynthesis. Early leaf senescence leads to substantial drops in rice yields. Whether and how DNA methylation regulates gene expression and affects leaf senescence remains elusive. Here, we demonstrate that mutations in rice ARGONAUTE 2 (OsAGO2) lead to premature leaf senescence, with chloroplasts in Osago2 having lower chlorophyll content and an abnormal thylakoid structure compared with those from wild‐type plants. We show that OsAGO2 associates with a 24‐nt microRNA and binds to the promoter region of OsNAC300, which causes DNA methylation and suppressed expression of OsNAC300. Overexpressing OsNAC300 causes the similar premature leaf senescence as Osago2 mutants and knocking out OsNAC300 in the Osago2 mutant background suppresses the early senescence of Osago2 mutants. Based on yeast one‐hybrid, dual‐luciferase, and electrophoresis mobility shift assays, we propose that OsNAC300 directly regulates transcription of the key rice aging gene NAC‐like, activated by APETALA3/PISTILLATA (OsNAP) to control leaf senescence. Our results unravel a previously unknown epigenetic regulatory mechanism underlying leaf senescence in which OsAGO2–OsNAC300–OsNAP acts as a key regulatory module of leaf senescence to maintain leaf function. [ABSTRACT FROM AUTHOR]

Published
2024
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