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Ni L.,Foshan Power Supply Bureau | Luo J.,Huazhong University of Science and Technology | Wang S.,Huazhong University of Science and Technology
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2011

This paper improves the ACE model and controller of conventional AGC system to suppress the frequency fluctuation caused by wind power disturbances. The strong randomness and intermittence of wind forces result in the random fluctuation of wind power outputs, which will have an adverse effect on the frequency control of power system. In this paper, a new controlled variable is introduced into the ACE model of AGC system, and fuzzy-PI strategy is used to regulate PI control parameters of the controller adaptively according to the range of frequency offset. The simulation results of a two-area electrical interconnected power system show that the improved AGC system developed in this study can effectively suppress frequency fluctuation caused by wind power disturbance. Source

Deng W.,Hunan University | Li X.,Hunan University | Liu Z.,Foshan Power Supply Bureau | Yan Y.,Hunan University | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

The output power of intermittent distributed generation (DG) such as distributed wind generation (DWG) and photovoltaic (PV) is random and the load is uncertain. Aiming at the investment expenses of intermittent DG and compensation capacitor, income of electricity sale, reduction of system power loss, voltage quality and emission reductions, the optimal configuration models of intermittent DG and capacitor were built using chance constrained programming method. Genetic algorithm was chosen for the optimal solution. The simulation results show that the comprehensively optimized allocation model has improved expected value of node voltage and the probability within normal range. The comprehensive optimization of economic benefit, environ-mental benefit and voltage quality were achieved, and the rationality and availability of the proposed model is verified. © 2012 Chin. Soc. for Elec. Eng. Source

Zhao Y.,Chongqing University | Wu X.,Foshan Power Supply Bureau | Xie K.,Chongqing University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2012

An approach for frequency instability risk assessment of bulk power system is proposed in this paper. Based on the dynamic frequency characteristic of spinning reserve, the model of frequency stability analysis considering under frequency load shedding is presented. Utilizing the non-sequential Monte Carlo simulation, risk indices such as instability probability, instability frequency, expected load shedding and frequency dynamic indices are calculated for probabilistic quantitative evaluation of frequency instability. The impact of spinning reserve and generators tripping on frequency instability are discussed. Moreover, the annual risk indices including or excluding uncertainty for multi-level load model are analyzed. Simulation results of IEEE-RTS79 verify that the proposed method is a powerful tool which can provide valuable reference information for identification of frequency instability risk and optimizing of under frequency load shedding scheme. Source

Lu K.,South China University of Technology | Zhang Y.,South China University of Technology | Ni W.-D.,Foshan Power Supply Bureau | Xia C.-J.,South China University of Technology
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

According to the problem that the traditional control scheme can not meet the requirement of low-voltage ride-through for DFIG, in this paper, based on the analysis of the stator and rotor transient process, we find the causes which affect the rotor over-current and DC bus overvoltage, and propose a new feedforward compensation method based on current control, that is, in the rotor side, adding a feedforward component which can reflect the attenuation of stator flux transient; in the grid side, adding a feedforward component which can reflect the power change between the two sides of converter. Finally, a DFIG model is built under PSCAD/EMTDC platform, the validity of this new control strategy is verified by simulation results through network voltage dip. Source

Zhan Q.-H.,Wuhan University | Zhan Q.-H.,Foshan Power Supply Bureau | Ruan J.-J.,Wuhan University | Zhong L.-H.,Guangdong Power Grid Corporation
Gaodianya Jishu/High Voltage Engineering | Year: 2010

The natural contamination of insulator is very important for the external insulation determination of overhead transmission line. Different types (shed and material) of insulator are installed on different towers of the same overhead transmission line. The equivalent salt deposit density (ESDD) and non-soluble deposit density (NSDD) of insulators are measured, and the influential factors of natural contamination are analyzed by comparing the ESDD and NSDD data. The results indicate that: rainfall, wind speed and shed have great influences on the natural contamination on the insulator surface. The contamination of the charged insulators is much higher than those not charged insulators. The outer-rib profile shed type insulators' self-cleaning properties is better, followed by the bell-shaped, and the deep under-rib sheds type insulator is the worst. The higher the structure height is, the lower the natural contamination will be. Under the same conditions, the porcelain insulators' natural contamination is lower than the glass insulators. NSDD and ESDD generally appear positive correlation. Source

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