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Zhou Y.,Guiyang Power Supply Bureau | Wang Q.G.,Chongqing University | Ye L.,Chongqing University | Zhou N.C.,Chongqing University
Advanced Materials Research | Year: 2014

This paper studies the instantaneous output power characteristics of photovoltaic inverters and its flexible power control strategy under unbalanced grid faults. Then the optimal parameters model of the power control is established with minimum integrated fluctuation amplitude of the active and reactive power as a goal when the constraint of the output current harmonic distortion of photovoltaic inverters is taken into account. Finally, the optimal power control of photovoltaic inverters based on dead-beat current tracking is realized and the feasibility of the proposed control strategy is verified with the power system transient software PSCAD/EMTDC. © (2014) Trans Tech Publications, Switzerland.


Zhang Y.F.,Guiyang Power Supply Bureau | Xu W.Q.,Guiyang Power Supply Bureau | Wang Q.G.,Chongqing University | Zhou N.C.,Chongqing University
Advanced Materials Research | Year: 2014

Modeling of the wind and PV hybrid microgrid is carried out by PSCAD/EMTDC. The model includes direct-drive wind power generator, Single-stage photovoltaic power generation system and storage battery. Simulate and analyze the operating characteristics of the microgrid running in grid-connected and islanding mode, which take into account the actual wind speed and light intensity. The simulation results show that the battery is able to regulate the voltage of the point of common coupling and smooth the power fluctuation of wind generator and PV generation system in the grid-connected mode. The microgrid can isolate itself from the grid in a rapid and seamless fashion when the battery adopting P/V and Q/f control strategy based on the droop characteristics. © (2014) Trans Tech Publications, Switzerland.


Xu W.Q.,Guiyang Power Supply Bureau | Wang Q.G.,Chongqing University | Pan S.,Chongqing University | Zhou N.C.,Chongqing University
Advanced Materials Research | Year: 2014

This paper presents a control strategy of solid oxide fuel cell (SOFC) generation system integrated into microgrid. To enhance the dynamic response of SOFC, storage battery is paralleled via a DC bus, and the hysteretic control of bi-directional DC-DC converter is adopted. The common DC-AC inverter adopts an improved droop control. The active synchronization control is applied to ensure the smooth mode transition of microgrid. The simulation results show the dynamic performance of SOFC generation system in different operation modes. © (2014) Trans Tech Publications, Switzerland.


Xu B.,Chongqing University | Lu J.-P.,Chongqing University | Pan X.,Beijing Electric Power Company | Xue Y.,Guiyang Power Supply Bureau | And 3 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

A new method to detect fault feeder in distribution network is proposed based on analyzing the strengths and weaknesses of the existing methods. The grounding capacitance is calculated with the single-phase grounding fault data, according to the relationship between the change of the current and voltage of the line before and after fault. Then the fault feeder is detected through the comparison between the transition resistances calculated on the basis of the capacitance. This method is immune to the neutral grounding mode, transition resistance and fault position, and is proved effective through the simulation.


Li T.,Guiyang Power Supply Bureau | Luo A.Q.,Chongqing University | Pan S.,Chongqing University | Xiong X.C.,Chongqing University | Zhou N.C.,Chongqing University
Advanced Materials Research | Year: 2014

The transient characteristics of induction generator (IG) were investigated in the paper, and the analytic formula of its stator current under three-phase short circuit in distribution network was derived. According to the change law of IG rotor speed under the grid fault, an evaluation method to determine the current peak of three-phase short circuit for induction generator in distribution grid is proposed. The correctness of the proposed method was verified by the fifth electromagnetic transient model of IG in PSCAD/EMTDC simulation software. © (2014) Trans Tech Publications, Switzerland.


Zhao R.,University of Sichuan | Zhang Y.,University of Sichuan | Li X.,University of Sichuan | Yang M.,Guiyang Power Supply Bureau | Chen H.,University of Sichuan
Dianwang Jishu/Power System Technology | Year: 2011

An L2 gain disturbance attenuation control approach to improve transient stability of HVDC power transmission system with multi feed-terminals at sending end is proposed. Firstly, the active power transmitted by DC lines at sending end is simplified as positive active load of sending end to construct nonlinear differential algebraic model of multi DC feed-terminal system at sending end; then using pre-feedback, the quasi Hamiltonian realization of the structure preserving model containing multi DC lines is obtained; finally, through nonlinear disturbance attenuation the control laws of HVDC system and generator excitation are obtained to make the L2 gain from system disturbance to output lower than given level. Simulation results show that the designed controller can ensure better asymptotic stability than traditional controller; besides, it can restrain disturbance effectively and possesses stronger robustness.


Gan G.,Chongqing University | Wang Z.,Chongqing University | Li R.,Guiyang Power Supply Bureau | Wang Q.,Guiyang Power Supply Bureau
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2014

The loop closing operation of a distribution network may generate a rather large surge current affecting safe and stable distribution network operation. A method for calculating the surge current from loop closing in distribution networks is proposed, and the accurate analytic formulas for calculating the surge currents of non-closing branches are deduced. Based on the Thevenin's theorem and the power flows before and after loop closing operation at optimum frequency, the decay time constant is computed. Based on the decay time constant and the power flow results before and after loop closing operation at the rated frequency, the surge currents of loop closing branch and non-closing branches can be calculated. Finally, the computing results of different methods, including PSCAD/EMTDC transient simulation, are compared and the results show the practicality and validity of the proposed method. Moreover, the results also show that the surge currents of some non-closing branches are larger than that of the closing branches. Thus it is quite necessary to check the surge currents of non-closing branches. © 2014 State Grid Electric Power Research Institute Press


Tang J.,Chongqing University | Zhuo R.,Chongqing University | Wu M.,Guiyang Power Supply Bureau | Tao J.,Chongqing University | Tang Y.,Chongqing Electric Power Company
Gaodianya Jishu/High Voltage Engineering | Year: 2013

Conventional methods of pattern recognition for partial discharge (PD) information in gas insulated switchgear (GIS) have many shortcomings, such as low recognition accuracy, high feature dimension, insufficient utilization of information, and so on. To overcome these shortcomings, on the basis of the Dempster-Shafer evidence theory, we introduced the fusion decision diagnosis of the signal analysis models of time-resolved partial discharge and phase-resolved partial discharge into the fault analysis of GIS, and achieved the comprehensive recognition of insulation defects in GIS. Further simulation and experiments show that, using the proposed method is able to make full use of effective information in recognitions and provide descriptions of all the information by regulations while having a superior ability to avoid misdiagnosis. Analyzing four typical defects shows that the comprehensive recognition rates of the two analysis modes are both above 80% accompanied with excellent complementary capability. In conclusion, the method reduces the dimension of defect features and improves the recognition accuracy.


Liu K.,GuiZhou Power Grid Co. | Guo Q.,Guangdong Electric Power Design Institute | Jiang H.,GuiZhou Power Grid Co. | Wang Y.,Guiyang Power Supply Bureau
Journal of Computational Information Systems | Year: 2014

Dedicated broadband cellular networks provides a promising way to collect tremendous distribution network and metering information for smart grid. The principal issue of dedicated network deployment is the coverage effectiveness due to deep shadow or severe wall penetration attenuation. This paper proposes a Device-to-Device (D2D) method to reconnect the user in outage to the attached base station with the relay of specific active cellular user in geographical proximity. The major contribution of this work is the close-form formulation derivation of D2D uplink relay link under the dedicated cellular networks. Numerical results demonstrate the validity of our formulation and the selection of D2D relay node can be determined based on the theoretical formulation. 1553-9105/Copyright © 2014 Binary Information Press

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