The Generator Excitation Control Based on the Quasi-sliding Mode Pseudo-variable Structure Control

Jian Hu,Lijun Fu 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

As an essential means of generator voltage regulation, excitation control plays an important role in controlling the stability of the power system. Therefore, the reasonable design of an excitation controller can help improve the system stability. In order to raise the robustness of the generator exciting system under outside interference and parametric perturbation and eliminate chattering in the sliding mode control, this paper presents a generator excitation control based on the quasi-sliding mode pseudo-variable structure control. A mathematical model of the synchronous generator is established by selecting its power, speed and voltage deviation as state variables. Then, according to the existing conditions of the quasi-sliding mode, a quasi-sliding mode pseudo-variable structure controller is designed, and the parameters of the controller are obtained with the method of pole configuration. Simulations show that compared with the existing methods, the proposed method is not only useful for accurate voltage regulation, but also beneficial to improving the robustness of the system at a time when perturbance happens in the system.

Further study on level ice resistance and channel resistance for an icebreaking vessel

Jian Hu,Li Zhou 대한조선학회 2016 International Journal of Naval Architecture and Oc Vol.8 No.2

In this paper, further research is carried out to investigate the resistance encountered by an icebreaking vessel travelling through level ice and channel ice at low speed range. The present paper focuses on experimental and calculated ice resistances by some empirical formulas in both level ice and channel ice. In order to achieve the research, extra model tests have been done in an ice basin. Based on the measurements from model test, it is found that there exists a relationship between ice resistance, minimum ice load, maximum ice load and the standard deviation of ice load for head on operation in level ice. In addition, both level ice resistance and channel ice resistance are calculated and compared with model test results.

Down-regulation of miRNA-452 is Associated with Adriamycin-resistance in Breast Cancer Cells

Hu, Qing,Gong, Jian-Ping,Li, Jian,Zhong, Shan-Liang,Chen, Wei-Xian,Zhang, Jun-Ying,Ma, Teng-Fei,Ji, Hao,Lv, Meng-Meng,Zhao, Jian-Hua,Tang, Jin-Hai Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.13

Adriamycin (ADR) is an important chemotherapeutic agent frequently used in treatment of breast cancer. However, resistance to ADR results in treatment failure in many patients. Recent studies have indicated that microRNAs (miRNAs) may play an important role in such drug-resistance. In the present study, microRNA-452 (miR-452) was found to be significantly down-regulated in adriamycin-resistant MCF-7 cells (MCF-7/ADR) compared with the parental MCF-7 cells by miRNA microarray and real-time quantitative PCR (RT-qPCR). MiR-452 mimics and inhibitors partially changed the adriamycin-resistance of breast cancer cells, as also confirmed by apoptosis assay. In exploring the potential mechanisms of miR-452 in the adriamycin-resistance of breast cancer cells, bioinformatics analysis, RT-qPCR and Western blotting showed that dysregulation of miR-452 played an important role in the acquired adriamycin-resistance of breast cancer, maybe at least in part via targeting insulin-like growth factor-1 receptor (IGF-1R).

Forecasting Day-ahead Electricity Price Using a Hybrid Improved Approach

Jian-Ming Hu,Jian-Zhou Wang 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.6

Electricity price prediction plays a crucial part in making the schedule and managing the risk to the competitive electricity market participants. However, it is a difficult and challenging task owing to the characteristics of the nonlinearity, non-stationarity and uncertainty of the price series. This study proposes a hybrid improved strategy which incorporates data preprocessor components and a forecasting engine component to enhance the forecasting accuracy of the electricity price. In the developed forecasting procedure, the Seasonal Adjustment (SA) method and the Ensemble Empirical Mode Decomposition (EEMD) technique are synthesized as the data preprocessing component; the Coupled Simulated Annealing (CSA) optimization method and the Least Square Support Vector Regression (LSSVR) algorithm construct the prediction engine. The proposed hybrid approach is verified with electricity price data sampled from the power market of New South Wales in Australia. The simulation outcome manifests that the proposed hybrid approach obtains the observable improvement in the forecasting accuracy compared with other approaches, which suggests that the proposed combinational approach occupies preferable predication ability and enough precision.

The Generator Excitation Control Based on the Quasi-sliding Mode Pseudo-variable Structure Control

Hu, Jian,Fu, Lijun The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

As an essential means of generator voltage regulation, excitation control plays an important role in controlling the stability of the power system. Therefore, the reasonable design of an excitation controller can help improve the system stability. In order to raise the robustness of the generator exciting system under outside interference and parametric perturbation and eliminate chattering in the sliding mode control, this paper presents a generator excitation control based on the quasi-sliding mode pseudo-variable structure control. A mathematical model of the synchronous generator is established by selecting its power, speed and voltage deviation as state variables. Then, according to the existing conditions of the quasi-sliding mode, a quasi-sliding mode pseudo-variable structure controller is designed, and the parameters of the controller are obtained with the method of pole configuration. Simulations show that compared with the existing methods, the proposed method is not only useful for accurate voltage regulation, but also beneficial to improving the robustness of the system at a time when perturbance happens in the system.

Further study on level ice resistance and channel resistance for an icebreaking vessel

Hu, Jian,Zhou, Li The Society of Naval Architects of Korea 2016 International Journal of Naval Architecture and Oc Vol.8 No.2

In this paper, further research is carried out to investigate the resistance encountered by an icebreaking vessel travelling through level ice and channel ice at low speed range. The present paper focuses on experimental and calculated ice resistances by some empirical formulas in both level ice and channel ice. In order to achieve the research, extra model tests have been done in an ice basin. Based on the measurements from model test, it is found that there exists a relationship between ice resistance, minimum ice load, maximum ice load and the standard deviation of ice load for head on operation in level ice. In addition, both level ice resistance and channel ice resistance are calculated and compared with model test results.

Experimental and numerical study on ice resistance for icebreaking vessels

Jian Hu,Li Zhou 대한조선학회 2015 International Journal of Naval Architecture and Oc Vol.7 No.3

Ice resistance is defined as the time average of all longitudinal forces due to ice acting on the ship. Estimation of ship’s resistance in ice-covered waters is very important to both designers and shipbuilders since it is closely related to propulsion of a ship and it determines the engine power of the ship. Good ice performance requires ice resistance should be as low as possible to allow different manoeuvres. In this paper, different numerical methods are presented to calculate ice resistance, including semi-analytical method and empirical methods. A model test of an icebreaking vessel that was done in an ice basin has been introduced for going straight ahead in level ice at low speed. Then the comparison between model test results and numerical results are made. Some discussions and suggestions are presented as well to provide an insight into icebreaking vessel design at early stage.

A Load Compensator Based on One-Cycle Control with Plug-In Repetitive Control

Jian Hu,Zhaohui Sun,Hao Ma,Guozhu Chen 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2

This study proposes a novel one-cycle control scheme with a plug-in repetitive controller for load compensator. The novelty of this scheme lies in the combination of high dynamics and the simplicity of a one-cycle controller and good steady-state harmonic suppression ability of the repetitive controller. In addition, the proposed scheme can reduce the effect of the harmonics in phase voltage for the existence of the repetitive controller. Finally, experimental results on a three-phase, four-wire, three-level load compensator are reported to validate the effectiveness of the proposed control scheme.

Stability Control of Energy Storage Voltage Source Inverters in Isolated Power Systems

Jian Hu,Lijun Fu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

Isolated power systems (IPS) are often characterized by a weak grid due to small power grids. The grid side voltage is no longer equivalent to an ideal voltage source of an infinitely big power grid. The conversion control of new energy sources, parameter perturbations as well as the load itself can easily cause the system voltage to oscillate or to become unstable. To solve this problem, increasing the energy-storage power sources is usually used to improve the reliability of a system. In order to provide support for the voltage, the energy-storage power source inverter needs an method to control the voltage source. Therefore, this paper has proposed the active damping control of a voltage source inverter (VSI) based on virtual compensation. By simplifying the VSI double closed-loop control, two feedback compensation channels have been constructed to reduce the VSI output impedance without changing the characteristics of the voltage gain of a system. This improvement allows systems to operate stably in a larger range. A frequency-domain analysis, and simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method.

Forecasting Day-ahead Electricity Price Using a Hybrid Improved Approach

Hu, Jian-Ming,Wang, Jian-Zhou The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.6

Electricity price prediction plays a crucial part in making the schedule and managing the risk to the competitive electricity market participants. However, it is a difficult and challenging task owing to the characteristics of the nonlinearity, non-stationarity and uncertainty of the price series. This study proposes a hybrid improved strategy which incorporates data preprocessor components and a forecasting engine component to enhance the forecasting accuracy of the electricity price. In the developed forecasting procedure, the Seasonal Adjustment (SA) method and the Ensemble Empirical Mode Decomposition (EEMD) technique are synthesized as the data preprocessing component; the Coupled Simulated Annealing (CSA) optimization method and the Least Square Support Vector Regression (LSSVR) algorithm construct the prediction engine. The proposed hybrid approach is verified with electricity price data sampled from the power market of New South Wales in Australia. The simulation outcome manifests that the proposed hybrid approach obtains the observable improvement in the forecasting accuracy compared with other approaches, which suggests that the proposed combinational approach occupies preferable predication ability and enough precision.