Analysis of Multi-Agent-Based Adaptive Droop-Controlled AC Microgrids with PSCAD

Zhongwen Li,Chuanzhi Zang,Peng Zeng,Haibin Yu,Hepeng Li,Shuhui Li 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2

A microgrid (MG) with integrated renewable energy resources can benefit both utility companies and customers. As a result, they are attracting a great deal of attention. The control of a MG is very important for the stable operation of a MG. The droop-control method is popular since it avoids circulating currents among the converters without using any critical communication between them. Traditional droop control methods have the drawback of an inherent trade-off between power sharing and voltage and frequency regulation. An adaptive droop control method is proposed, which can operate in both the island mode and the grid-connected mode. It can also ensure smooth switching between these two modes. Furthermore, the voltage and frequency of a MG can be restored by using the proposed droop controller. Meanwhile, the active power can be dispatched appropriately in both operating modes based on the capacity or running cost of the Distributed Generators (DGs). The global information (such as the average voltage and output active power of the MG and so on) required by the proposed droop control method to restore the voltage and frequency deviations can be acquired distributedly based on the Multi Agent System (MAS). Simulation studies in PSCAD demonstrate the effectiveness of the proposed control method.

Analysis of Multi-Agent-Based Adaptive Droop-Controlled AC Microgrids with PSCAD: Modeling and Simulation

Li, Zhongwen,Zang, Chuanzhi,Zeng, Peng,Yu, Haibin,Li, Hepeng,Li, Shuhui The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2

A microgrid (MG) with integrated renewable energy resources can benefit both utility companies and customers. As a result, they are attracting a great deal of attention. The control of a MG is very important for the stable operation of a MG. The droop-control method is popular since it avoids circulating currents among the converters without using any critical communication between them. Traditional droop control methods have the drawback of an inherent trade-off between power sharing and voltage and frequency regulation. An adaptive droop control method is proposed, which can operate in both the island mode and the grid-connected mode. It can also ensure smooth switching between these two modes. Furthermore, the voltage and frequency of a MG can be restored by using the proposed droop controller. Meanwhile, the active power can be dispatched appropriately in both operating modes based on the capacity or running cost of the Distributed Generators (DGs). The global information (such as the average voltage and output active power of the MG and so on) required by the proposed droop control method to restore the voltage and frequency deviations can be acquired distributedly based on the Multi Agent System (MAS). Simulation studies in PSCAD demonstrate the effectiveness of the proposed control method.

Adaptive Chaotic Gray Wolf Optimizer-Based Optimization of Decentralized AGC and Power Dispatching Controllers for Integrated Energy System with Heterogeneous Power Sources

Li Zhongwen,Bai Ningning,Cheng Zhiping,Wang Yi,Si Jikai 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.2

With the increasing use of renewable energy sources connected to inverters in modern power systems, traditional units’ rotary inertia and frequency regulation capacity are becoming inadequate. Therefore, exploring various types of frequency regulation resources is essential. However, these resources come with diferent system models, capacities, and response speeds, posing a signifcant challenge to automatic generation control (AGC). To address this issue and enhance the frequency regulation performance of these resources, a novel distributed coordination AGC method is proposed. The proposed method allows each frequency regulation unit to utilize a separate load frequency control (LFC) controller to participate in frequency regulation based on the area control error information calculated by the dispatching center. To ensure the coordination between the heterogeneous frequency regulation resources, an adaptive chaotic gray wolf algorithm is proposed to tune the parameters of the LFC controller. Furthermore, to release the fast frequency regulation ability of high-speed frequency regulation units and better prepare for the next round of frequency regulation service, an event-triggered power dispatching strategy is proposed. Simulation results of a single-area power system with fve diferent frequency regulation units demonstrate the superior performance of the proposed AGC method.

Correction: Adaptive Chaotic Gray Wolf Optimizer-Based Optimization of Decentralized AGC and Power Dispatching Controllers for Integrated Energy System with Heterogeneous Power Sources

Li Zhongwen,Bai Ningning,Cheng Zhiping,Wang Yi,Si Jikai 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.3

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Histone acetyltransferase inhibitors antagonize AMP-activated protein kinase in postmortem glycolysis

Qiong Li,Zhongwen Li,Aihua Lou,Zhenyu Wang,Dequan Zhang,Qingwu W. Shen 아세아·태평양축산학회 2017 Animal Bioscience Vol.30 No.6

Objective: The purpose of this study was to investigate the influence of AMP-activated protein kinase (AMPK) activation on protein acetylation and glycolysis in postmortem muscle to better understand the mechanism by which AMPK regulates postmortem glycolysis and meat quality. Methods: A total of 32 mice were randomly assigned to four groups and intraperitoneally injected with 5-Aminoimidazole-4-carboxamide1-β-D-ribofuranoside (AICAR, a specific activator of AMPK), AICAR and histone acetyltransferase inhibitor II, or AICAR, Trichostatin A (TSA, an inhibitor of histone deacetylase I and II) and Nicotinamide (NAM, an inhibitor of the Sirt family deacetylases). After mice were euthanized, the Longissimus dorsi muscle was collected at 0 h, 45 min, and 24 h postmortem. AMPK activity, protein acetylation and glycolysis in postmortem muscle were measured. Results: Activation of AMPK by AICAR significantly increased glycolysis in postmortem muscle. At the same time, it increased the total acetylated proteins in muscle 45 min postmortem. Inhibition of protein acetylation by histone acetyltransferase inhibitors reduced AMPK activation induced increase in the total acetylated proteins and glycolytic rate in muscle early postmortem, while histone deacetylase inhibitors further promoted protein acetylation and glycolysis. Several bands of proteins were detected to be differentially acetylated in muscle with different glycolytic rates. Conclusion: Protein acetylation plays an important regulatory role in postmortem glycolysis. As AMPK mediates the effects of pre-slaughter stress on postmortem glycolysis, protein acetylation is likely a mechanism by which antemortem stress influenced postmortem metabolism and meat quality though the exact mechanism is to be elucidated.

Integrative applications of network pharmacology and molecular docking: An herbal formula ameliorates H9c2 cells injury through pyroptosis

Zhongwen Qi,Zhipeng Yan,Yueyao Wang,Nan Ji,Xiaoya Yang,Ao Zhang,Meng Li,Fengqin Xu,Junping Zhang The Korean Society of Ginseng 2023 Journal of Ginseng Research Vol.47 No.2

Background: QiShen YiQi pills (QSYQ) is a Traditional Chinese Medicine (TCM) formula, which has a significant effect on the treatment of patients with myocardial infarction (MI) in clinical practice. However, the molecular mechanism of QSYQ regulation pyroptosis after MI is still not fully known. Hence, this study was designed to reveal the mechanism of the active ingredient in QSYQ. Methods: Integrated approach of network pharmacology and molecular docking, were conducted to screen active components and corresponding common target genes of QSYQ in intervening pyroptosis after MI. Subsequently, STRING and Cytoscape were applied to construct a PPI network, and obtain candidate active compounds. Molecular docking was performed to verify the binding ability of candidate components to pyroptosis proteins and oxygen-glucose deprivation (OGD) induced cardiomyocytes injuries were applied to explore the protective effect and mechanism of the candidate drug. Results: Two drug-likeness compounds were preliminarily selected, and the binding capacity between Ginsenoside Rh2 (Rh2) and key target High Mobility Group Box 1 (HMGB1)was validated in the form of hydrogen bonding. 2 μM Rh2 prevented OGD-induced H9c2 death and reduced IL-18 and IL-1β levels, possibly by decreasing the activation of the NLRP3 inflammasome, inhibiting the expression of p12-caspase1, and attenuating the level of pyroptosis executive protein GSDMD-N. Conclusions: We propose that Rh2 of QSYQ can protect myocardial cells partially by ameliorating pyroptosis, which seems to have a new insight regarding the therapeutic potential for MI.

Seismic performance of L-shaped RC walls sustaining Unsymmetrical bending

Zhongwen Zhang,Bing Li 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.3

Reinforced concrete (RC) structural walls with L-shaped sections are commonly used in RC buildings. The walls are often expected to sustain biaxial load and Unsymmetrical bending in an earthquake event. However, there currently exists limited experimental evidence regarding their seismic behaviour in these lateral loading directions. This paper makes experimental and numerical investigations to these walls behaviours. Experimental evidences are presented for four L-shaped wall specimens which were tested under simulated seismic load from different lateral directions. The results highlighted some distinct behaviour of L-shaped walls sustaining Unsymmetrical bending relating to their seismic performance. First, due to the Unsymmetrical bending, out-of-plane reaction forces occur for these walls, which contribute to accumulation of the out-of-plane deformations of the wall, especially when out-of-plane stiffness of the section is reduced by horizontal cracks in the cyclic load. Secondly, cracking was found to affect shear centre of the specimens loaded in the Unsymmetrical bending direction. The shear centre of these specimens distinctly differs in the flange in the positive and negative loading direction. Cracking of the flange also causes significant warping in the bottom part of the wall, which eventually lead to out-of-plane buckling failure.

Shear lag effect in steel-concrete composite beam in hogging moment

Da Luo,Zhongwen Zhang,Bing Li 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.1

Shear lag effect can be an important phenomenon to consider in design of the steel-concrete composite beams. Researchers have found that the effect can be strongly related with the moment distribution, the stiffness and the ductility of the composite beams. For continuous composite beams expected to sustain hogging moment, the shear lag effect can be more distinct as cracking of the concrete slab reduces its shear stiffness. Despite its influences on behaviour of the steel-concrete composite beams, a method for calculating the shear lag effect in steel-concrete composite beams sustaining hogging moment is still not available. Shear lag effect in steel-concrete composite beams sustaining hogging moment is investigated in this paper. A method was proposed specifically for predicting the effect in the cracked part of the steel-concrete composite beam. The method is validated against available experimental data. At last, FE studies are conducted for steel-concrete composite beams with different design parameters, loading conditions and boundary conditions to further investigate the shear lag effect and compare with the proposed method.

Moment redistribution of RC continuous beams: Re-examination of code provisions

Da Luo,Zhongwen Zhang,Bing Li 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.5

Many codes allow designers to use the bending moment diagram computed by elastic analysis and modify it by a certain amount of moment redistribution (MR) to account for plastic behaviour of continuous beams. However, several researchers indicated that the MR at the ultimate limit state (u) for some beams deviate significantly from the specified values of various codes. This paper examines the applicability of the provisions on u in ACI 318-19 and Eurocode 2 through numerical investigations and comprehensively explores the influencing factors. The results show that some parameters not considered in those codes influence u to a certain extent, where the ratio of tensile reinforcement ratio at intermediate support to tensile reinforcement ratio at midspan (s1/s2) and load type are crucial parameters to consider. The specific combination of these two parameters may make the codes overestimate or significantly underestimate the u. On the other hand, the yield state of both critical sections is found to have an important influence on the influence degree of each parameter on u. The yield conditions are investigated, and an empirical judgment equation is proposed. In addition, the influence laws of the critical parameters on u have been further proved by theoretical derivation. Finally, due to t is found to have a better linear correlation with βu than xu/d, equations as a function of t for predicting the u of continuous beams under the two loads are proposed, respectively.

Distributed Secondary Control of AC Microgrid and its Frequency Domain Analysis Considering Time Delay

Cheng Zhiping,Wang Kaifang,Li Zhongwen,Wu Haotian,Zhi Changyi,Zhang Jinbin 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

In this paper, distributed secondary control of AC microgrid (MG) is studied and the infuence of communication delay on its control performance is analyzed and verifed. Firstly, a secondary control strategy for the MG is designed to achieve frequency recovery and proportional active power dispatch. Secondly, the stability of the MG system is analyzed in the frequency domain and a rigorous formula is derived to calculate the delay margin for the stability of the distributed secondary control with communication delays. The theoretical calculation results of the stability margin are approximately consistent with the simulation results, with an error of only 1.27%. The efects of the algorithm gains, communication topology, and connection weights on the delay margin are discussed based on the derived formula. The results demonstrate that the algorithm gain is inversely proportional to the delay margin. Changes in the communication topology and connection weights lead to changes in the maximum eigenvalue of the adjacency matrix L, which in turn afects the delay margin. Moreover, the infuence of time-varying delays is considered. The system can tolerate greater time-varying delays than fxed delays. Simulation and experimental results validate the efectiveness and feasibility of the proposed method.