A New Constraint Handling Method for Economic Dispatch

Li, Xueping,Xiao, Canwei,Lu, Zhigang The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.3

For practical consideration, economic dispatch (ED) problems in power system have non-smooth cost functions with equality and inequality constraints that makes the problems complex constrained nonlinear optimization problems. This paper proposes a new constraint handling method for equality and inequality constraints which is employed to solve ED problems, where the incremental rate is employed to enhance the modification process. In order to prove the applicability of the proposed method, the study cases are tested based on the classical particle swarm optimization (PSO) and differential evolution (DE) algorithm. The proposed method is evaluated for ED problems using six different test systems: 6-, 15-, 20-, 38-, 110- and 140-generators system. Simulation results show that it can always find the satisfactory solutions while satisfying the constraints.

Hierarchical Optimal Reactive Power Dispatch for Active Distribution Network with Multi-microgrids

Li Xueping,Zhao Wanzhao,Lu Zhigang 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3

The interconnection of active distribution network and multi-microgrids leads to the increase of variable dimension of optimal reactive power dispatch. The overall reactive power dispatch will face the problems of high dimension, slow convergence, and reduced accuracy. Meanwhile, the decomposition dispatch requires a large number of coordination iterations. Hence, this paper proposes a hierarchical optimal reactive power dispatch method for active distribution network with multi-microgrids based on differential evolution algorithm and the network loss sensitivity. In this method, the upper layer takes the minimum loss of the distribution network as the goal, regards each microgrid as a generator node, and formulates the interactive power between each microgrid and the distribution network. The lower layer aims to minimize the network loss of the microgrid, regards the point of common coupling as the balance node, and make the power of the lower layer meet the constraints of the upper layer in the form of penalty function. To minimize the network loss of the whole network, the sensitivity is calculated to correct the output of reactive power equipment for further optimization. The improved IEEE-33 bus distribution network system is used to verify the method, and the results are compared with the global optimization results. Due to the reduction of the network scale, the number of iterations of each system of hierarchical optimization is 1000, which is greatly reduced compared with 10,000 of the overall optimization. The results show that the proposed method improves the economy of active distribution network system with multi-microgrids and significantly shortens the running time.

Static Detection of False Data in the Power Grid by Fusing Structure and Attributes of Node

Li Xueping,Li Xuanxuan,Lu Zhigang 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.6

False data injection attack can evade the traditional state estimation in the power system, resulting in the historical data may have been polluted. Under such circumstances, the contaminated historical data cannot provide the priori data, so data-driven detection cannot be carried out. Hence, this paper proposes a static detection method of false data based on the similarity characteristics of network nodes at a certain time, where structure and attributes of nodes are fused to express nodes based on the egonet model of power grid. In addition, to improve the accuracy of clustering, the detection rate is adopted in the clustering method. The method is tested in IEEE118-bus and 2383-bus systems. The simulation results show that proposed method is effective, and can detect the possible false data injection problems in the power system over 80%.

A New Constraint Handling Method for Economic Dispatch

Xueping Li,Canwei Xiao,Zhigang Lu 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.3

For practical consideration, economic dispatch (ED) problems in power system have nonsmooth cost functions with equality and inequality constraints that makes the problems complex constrained nonlinear optimization problems. This paper proposes a new constraint handling method for equality and inequality constraints which is employed to solve ED problems, where the incremental rate is employed to enhance the modification process. In order to prove the applicability of the proposed method, the study cases are tested based on the classical particle swarm optimization (PSO) and differential evolution (DE) algorithm. The proposed method is evaluated for ED problems using six different test systems: 6-, 15-, 20-, 38-, 110- and 140-generators system. Simulation results show that it can always find the satisfactory solutions while satisfying the constraints.

Differential Evolution Algorithm Based on State Transition of Specific Individuals for Economic Dispatch Problems with Valve Point Effects

Li Xueping,Xu Jian,Lu Zhigang 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2

Economic Dispatch problem with valve-point eff ects is a complex solution problem involving the practical constraints of equality and inequality. The paper proposes a diff erential evolution algorithm based on specifi c individuals of state transition to solve small, medium and large-economic dispatch problems with valve-point eff ects. The core of DE-STA is to use the state transition to update specifi c individuals after a diff erential evolution of the population, which improves the optimization effi ciency, robustness and accuracy of the algorithm. Moreover, a new state operator of translation transformation is adopted to improve effi ciency of state transition, which introduces individuals of information exchange. Compared with the traditional DE and other algorithms, better robustness, faster convergence speed and accuracy results of the DE-STA are demonstrated by solving small, medium and large-economic dispatch problems with valve-point eff ects related to 13-, 40- and 140-unit test system

Coronary CT Angiography with Knowledge-Based Iterative Model Reconstruction for Assessing Coronary Arteries and Non-Calcified Predominant Plaques

Tao Li,Tian Tang,Li Yang,Xinghua Zhang,Xueping Li,Chuncai Luo 대한영상의학회 2019 Korean Journal of Radiology Vol.20 No.5

Objective: To assess the effects of iterative model reconstruction (IMR) on image quality for demonstrating non-calcific highrisk plaque characteristics of coronary arteries. Materials and Methods: This study included 66 patients (53 men and 13 women; aged 39–76 years; mean age, 55 ± 13 years) having single-vessel disease with predominantly non-calcified plaques evaluated using prospective electrocardiogramgated 256-slice CT angiography. Paired image sets were created using two types of reconstruction: hybrid iterative reconstruction (HIR) and IMR. Plaque characteristics were compared using the two algorithms. The signal-to-noise ratio (SNR) and contrastto-noise ratio (CNR) of the images and the CNR between the plaque and adjacent adipose tissue were also compared between the two reformatted methods. Results: Seventy-seven predominantly non-calcified plaques were detected. Forty plaques showed napkin-ring sign with the IMR reformatted method, while nineteen plaques demonstrated napkin-ring sign with HIR. There was no statistically significant difference in the presentation of positive remodeling, low attenuation plaque, and spotty calcification between the HIR and IMR reconstructed methods (all p > 0.5); however, there was a statistically significant difference in the ability to discern the napkin-ring sign between the two algorithms (χ2 = 12.12, p < 0.001). The image noise of IMR was lower than that of HIR (10 ± 2 HU versus 12 ± 2 HU; p < 0.01), and the SNR and CNR of the images and the CNR between plaques and surrounding adipose tissues on IMR were better than those on HIR (p < 0.01). Conclusion: IMR can significantly improve image quality compared with HIR for the demonstration of coronary artery and atherosclerotic plaques using a 256-slice CT.

Computational fluid dynamics simulation of hydrodynamics in an uncovered unbaffled tank agitated by pitched blade turbines

Liangchao Li,Jiajun Wang,Lianfang Feng,Xueping Gu 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.11

Computational fluid dynamics (CFD) simulations were applied for evaluating the hydrodynamics characteristics in an uncovered unbaffled tank agitated by pitched blade turbines. A volume of fluid (VOF) method along with a Reynolds stress model (RSM) was used to capture the gas-liquid interface and the turbulence flow in the tank. The reliability and accuracy of the simulations are verified. The simulation results show that the vortex can be divided into central zone and peripheral zone, and flow field in the tank can be divided into forced vortex flow region and free vortex flow region. With the increase of impeller speed, the vortex becomes deeper, while the critical radius of the two zones keeps almost unchanged. The impeller clearance and the rotational direction have little effect on the vortex shape. The vortex becomes deeper with increasing of the impeller diameter or the blade angles at the same rotational speed. Power number is little influenced by the impeller speed, and decreases by about 30% when impeller diameter varies from 0.25T to 0.5T. When blade angle varies from 30o to 90o, power number increases by about 2.32-times. Power number in uncovered unbaffled tank is much smaller than that in baffled tank, but is very close to that in a covered unbaffled tank. The discrepancy of power number in uncovered unbaffled tank and that in covered unbaffled tank is less than 10%.

CONTROLLER DESIGN FOR SOFT-DISABILITY REMEDY OF THE ELECTRIC POWER STEERING SYSTEM

Xin Li,Xueping Zhao,Jie Chen,Jinlai Men 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.4

The electric power steering (EPS) system is designed to reduce the effort exerted by driver on the steering wheel. One of the most common and critical failures of EPS is the soft-disability of the torque sensor or the loss of its signal, which leads to the instant shutdown of the EPS system while turning and causes serious traffic accidents. In this paper, a novel controller based on the self-alignment torque (SAT) estimation was designed to remedy the soft-disability of EPS system. After the SAT estimation method was verified by the empirical Magic Formula (MF) tire model, the remedy control strategy based on the SAT estimation was developed and evaluated by simulations under step and sinusoidal inputs. To further evaluate the performance of the controller on a real vehicle, experiments on a real EPS system were implemented under step and sinusoidal inputs. The results of simulation and experiment using the controller based on estimated SAT showed this controller to be feasible and capable of eliminating the abrupt reaction torque increment caused by shutdown of EPS and of remedying the soft-disability of EPS system under common input signals. The electric power steering (EPS) system is designed to reduce the effort exerted by driver on the steering wheel. One of the most common and critical failures of EPS is the soft-disability of the torque sensor or the loss of its signal, which leads to the instant shutdown of the EPS system while turning and causes serious traffic accidents. In this paper, a novel controller based on the self-alignment torque (SAT) estimation was designed to remedy the soft-disability of EPS system. After the SAT estimation method was verified by the empirical Magic Formula (MF) tire model, the remedy control strategy based on the SAT estimation was developed and evaluated by simulations under step and sinusoidal inputs. To further evaluate the performance of the controller on a real vehicle, experiments on a real EPS system were implemented under step and sinusoidal inputs. The results of simulation and experiment using the controller based on estimated SAT showed this controller to be feasible and capable of eliminating the abrupt reaction torque increment caused by shutdown of EPS and of remedying the soft-disability of EPS system under common input signals.

Evaluation fo Field Performance and Approval criteria in Herbicide Registration in China

Zhen Li,Xuehua An,Xueping Zhao 한국잡초학회 2011 한국잡초학회 별책(학술대회 초록집) Vol.31 No.2

Changes in Properties of White Shrimp (Litopenaeus vannamei) Protein during Thermal Denaturation

Ruichang Gao,Xueping Feng,Wenwen Li,Li Yuan,Jing Ge,Daoli Lu,Bin Chen,Gang Yu 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.1

Changes in white shrimp (Litopenaeus vannamei) protein during thermal denaturation were studied using Raman spectroscopy and isotopic H/D exchange. Denaturation of shrimp protein began after heating for 10 min at 50oC. A decrease in the percentage of α-helices accompanied by an increase in the percentage of β-sheets occurred while the total percentage of disordered structures increased. With extension of the exchange time, the relative intensity of the O-D bond increased, accompanied by a higher relative O-D bond intensity for heated shrimp, compared with unheated shrimp. H/D exchange revealed a higher rate of deuteration kinetics in heated shrimp than for unheated shrimp, especially during the first 2 h, consistent with water loss from denatured white shrimp protein. Physical property changes in muscle tissue can be caused by changes in hydrogen bonding and hydrophobicity during thermal processes.