Microgrid (MG) is a small entity of electrical network which comprises of various Distributed Generation (DG) sources, storage devices, and group of loads in various classes. MG provides reliable and secure energy sup...Microgrid (MG) is a small entity of electrical network which comprises of various Distributed Generation (DG) sources, storage devices, and group of loads in various classes. MG provides reliable and secure energy supply to the critical loads of communities while operating either in on-grid or off-grid mode. In this study, a coordinated power management control strategy for a typical low voltage (LV) MG network with integration of solar Photovoltaic (PV) and storage facility has been developed and analysed in Matlab-Simu-link software environment at various modes (on-grid, off-grid, and on-grid to off-grid transition) of MG operation. Solar PV and battery power inverters are considered as grid-support grid-forming (GsGfm) Voltage Source Inverter (VSI) with the implementation of modified droop and virtual output impedance control strategies. Proposed control strategy supports coordinated control operation between PV units and battery storage, equal power sharing among the DG sources, and smooth MG mode transition with regulation of voltage and frequency level in MG network. In addition, voltage and current THD level were analysed and verified as per the standard of AS4777.展开更多
The core of grid technology is just to solve the problem of resource share and to eliminate information island and resource island. Thus, it is a perfect approach to apply the grid technology to armored equipment mate...The core of grid technology is just to solve the problem of resource share and to eliminate information island and resource island. Thus, it is a perfect approach to apply the grid technology to armored equipment materiel support. Firstly, the military and function demands of armored equipment materiel support grid are analyzed. Besides, according to the function demand, the system structure of armored equipment materiel support grid is designed. Finally, the organizational structure of armored equipment materiel support grid is established in this paper based on actual armored equipment materiel support.展开更多
The brushless doubly-fed wind power system based on conventional power control strategies lacks ‘inertia’ and the ability to support grid,which leads to the decline of grid stability.Therefore,a control strategy of ...The brushless doubly-fed wind power system based on conventional power control strategies lacks ‘inertia’ and the ability to support grid,which leads to the decline of grid stability.Therefore,a control strategy of brushless doubly-fed reluctance generator(BDFRG) based on virtual synchronous generator(VSG) control is proposed to solve the problem in this paper.The output characteristics of BDFRG based on VSG are similar to a synchronous generator(SG),which can support the grid frequency and increase the system ‘inertia’.According to the mathematical model of BDFRG,the inner loop voltage source control of BDFRG is derived.In addition,the specific structure and parameter selection principle of outer loop VSG control are expounded.The voltage source control inner loop of BDFRG is combined with the VSG control outer loop to establish the overall architecture of BDFRG-VSG control strategy.Finally,the effectiveness and feasibility of the proposed strategy are verified in the simulation.展开更多
Online fault detection is one of the key technologies to improve the performance of cloud systems. The current data of cloud systems is to be monitored, collected and used to reflect their state. Its use can potential...Online fault detection is one of the key technologies to improve the performance of cloud systems. The current data of cloud systems is to be monitored, collected and used to reflect their state. Its use can potentially help cloud managers take some timely measures before fault occurrence in clouds. Because of the complex structure and dynamic change characteristics of the clouds, existing fault detection methods suffer from the problems of low efficiency and low accuracy. In order to solve them, this work proposes an online detection model based on asystematic parameter-search method called SVM-Grid, whose construction is based on a support vector machine(SVM). SVM-Grid is used to optimize parameters in SVM. Proper attributes of a cloud system's running data are selected by using Pearson correlation and principal component analysis for the model. Strategies of predicting cloud faults and updating fault sample databases are proposed to optimize the model and improve its performance.In comparison with some representative existing methods, the proposed model can achieve more efficient and accurate fault detection for cloud systems.展开更多
【目的】“双高”电力系统(高比例可再生能源和高比例电力电子设备)低惯性、低阻尼的特征使电网在频率、电压等稳定问题面临着严峻的挑战。构网型储能(grid-forming energy storage,GFM-ES)具有频率调节和电压控制的能力,针对其特性、...【目的】“双高”电力系统(高比例可再生能源和高比例电力电子设备)低惯性、低阻尼的特征使电网在频率、电压等稳定问题面临着严峻的挑战。构网型储能(grid-forming energy storage,GFM-ES)具有频率调节和电压控制的能力,针对其特性、应用场景和研究展望等方面进行综述。【方法】首先从GFM-ES和跟网型储能的区别以及控制方法等方面阐述了GFM-ES的主要特点;然后从频率支撑、电压支撑和黑启动等方面介绍了GFM-ES的主要应用场景;最后从GFM-ES的稳定性、优化配置和实际工程应用等方面提出了研究展望。【结论】构网型变流器的稳定性对储能机组的运行特性具有重要影响,需要进一步关注稳定问题的诱导原因、参数整定、控制和限流策略切换等;GFM-ES规划配置中,需要在功能性、复杂性、成本等方面进行权衡,以及构网型和跟网型储能的混合配置有待继续研究;加强GFM-ES机组之间的协调性和运行交互性,完善工程测试规范和标准,推动其在交直流混合电网及高压输电网络的应用。展开更多
随着近海风电资源开发饱和,远海风电的开发利用日益受到重视。柔性直流输电技术(voltage source converter based-high voltage direct current transmission,VSC-HVDC)凭借其灵活可控、可孤岛运行及适应远距离输电等优势,成为规模化远...随着近海风电资源开发饱和,远海风电的开发利用日益受到重视。柔性直流输电技术(voltage source converter based-high voltage direct current transmission,VSC-HVDC)凭借其灵活可控、可孤岛运行及适应远距离输电等优势,成为规模化远海风电输送的首选技术。然而,大容量的海上风电柔直工程大规模接入,将给电网带来弱系统、低惯量和电压支撑不足等稳定性挑战。因此,提升海上风电柔性直流外送系统的主动支撑能力成为国内外研究热点。为此,首先介绍了海上风电柔直外送系统拓扑结构和传统控制策略。接着,从有功和无功支撑2个层面,讨论了跟网型控制结构下通过附加控制策略实现主动支撑的方法及其局限性。然后,探讨了对构网型主动支撑技术的需求与相关标准,并梳理分析了构网型控制结构下不同的技术路线及其特点。最后,展望了技术发展趋势,并指出了当前研究及工程应用中面临的关键问题及挑战。展开更多
文摘Microgrid (MG) is a small entity of electrical network which comprises of various Distributed Generation (DG) sources, storage devices, and group of loads in various classes. MG provides reliable and secure energy supply to the critical loads of communities while operating either in on-grid or off-grid mode. In this study, a coordinated power management control strategy for a typical low voltage (LV) MG network with integration of solar Photovoltaic (PV) and storage facility has been developed and analysed in Matlab-Simu-link software environment at various modes (on-grid, off-grid, and on-grid to off-grid transition) of MG operation. Solar PV and battery power inverters are considered as grid-support grid-forming (GsGfm) Voltage Source Inverter (VSI) with the implementation of modified droop and virtual output impedance control strategies. Proposed control strategy supports coordinated control operation between PV units and battery storage, equal power sharing among the DG sources, and smooth MG mode transition with regulation of voltage and frequency level in MG network. In addition, voltage and current THD level were analysed and verified as per the standard of AS4777.
文摘The core of grid technology is just to solve the problem of resource share and to eliminate information island and resource island. Thus, it is a perfect approach to apply the grid technology to armored equipment materiel support. Firstly, the military and function demands of armored equipment materiel support grid are analyzed. Besides, according to the function demand, the system structure of armored equipment materiel support grid is designed. Finally, the organizational structure of armored equipment materiel support grid is established in this paper based on actual armored equipment materiel support.
基金Supported by National Natural Science Foundation Of China （60873235, 60473099）, Science-Technology Development Key Project of Jilin Province of China （20080318）, and Program of New Century Excellent Talents in University of China （NCET-06-0300）
基金supported in part by the National Natural Science Foundation of China under Grant 51537007。
文摘The brushless doubly-fed wind power system based on conventional power control strategies lacks ‘inertia’ and the ability to support grid,which leads to the decline of grid stability.Therefore,a control strategy of brushless doubly-fed reluctance generator(BDFRG) based on virtual synchronous generator(VSG) control is proposed to solve the problem in this paper.The output characteristics of BDFRG based on VSG are similar to a synchronous generator(SG),which can support the grid frequency and increase the system ‘inertia’.According to the mathematical model of BDFRG,the inner loop voltage source control of BDFRG is derived.In addition,the specific structure and parameter selection principle of outer loop VSG control are expounded.The voltage source control inner loop of BDFRG is combined with the VSG control outer loop to establish the overall architecture of BDFRG-VSG control strategy.Finally,the effectiveness and feasibility of the proposed strategy are verified in the simulation.
基金supported by the National Natural Science Foundation of China(61472005,61201252)CERNET Innovation Project(NGII20160207)
文摘Online fault detection is one of the key technologies to improve the performance of cloud systems. The current data of cloud systems is to be monitored, collected and used to reflect their state. Its use can potentially help cloud managers take some timely measures before fault occurrence in clouds. Because of the complex structure and dynamic change characteristics of the clouds, existing fault detection methods suffer from the problems of low efficiency and low accuracy. In order to solve them, this work proposes an online detection model based on asystematic parameter-search method called SVM-Grid, whose construction is based on a support vector machine(SVM). SVM-Grid is used to optimize parameters in SVM. Proper attributes of a cloud system's running data are selected by using Pearson correlation and principal component analysis for the model. Strategies of predicting cloud faults and updating fault sample databases are proposed to optimize the model and improve its performance.In comparison with some representative existing methods, the proposed model can achieve more efficient and accurate fault detection for cloud systems.
文摘【目的】“双高”电力系统(高比例可再生能源和高比例电力电子设备)低惯性、低阻尼的特征使电网在频率、电压等稳定问题面临着严峻的挑战。构网型储能(grid-forming energy storage,GFM-ES)具有频率调节和电压控制的能力,针对其特性、应用场景和研究展望等方面进行综述。【方法】首先从GFM-ES和跟网型储能的区别以及控制方法等方面阐述了GFM-ES的主要特点;然后从频率支撑、电压支撑和黑启动等方面介绍了GFM-ES的主要应用场景;最后从GFM-ES的稳定性、优化配置和实际工程应用等方面提出了研究展望。【结论】构网型变流器的稳定性对储能机组的运行特性具有重要影响,需要进一步关注稳定问题的诱导原因、参数整定、控制和限流策略切换等;GFM-ES规划配置中,需要在功能性、复杂性、成本等方面进行权衡,以及构网型和跟网型储能的混合配置有待继续研究;加强GFM-ES机组之间的协调性和运行交互性,完善工程测试规范和标准,推动其在交直流混合电网及高压输电网络的应用。
文摘随着近海风电资源开发饱和,远海风电的开发利用日益受到重视。柔性直流输电技术(voltage source converter based-high voltage direct current transmission,VSC-HVDC)凭借其灵活可控、可孤岛运行及适应远距离输电等优势,成为规模化远海风电输送的首选技术。然而,大容量的海上风电柔直工程大规模接入,将给电网带来弱系统、低惯量和电压支撑不足等稳定性挑战。因此,提升海上风电柔性直流外送系统的主动支撑能力成为国内外研究热点。为此,首先介绍了海上风电柔直外送系统拓扑结构和传统控制策略。接着,从有功和无功支撑2个层面,讨论了跟网型控制结构下通过附加控制策略实现主动支撑的方法及其局限性。然后,探讨了对构网型主动支撑技术的需求与相关标准,并梳理分析了构网型控制结构下不同的技术路线及其特点。最后,展望了技术发展趋势,并指出了当前研究及工程应用中面临的关键问题及挑战。
