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Shan R.,Tsinghua University | Chen L.,Tsinghua University | Shen C.,Tsinghua University | Ke S.,Tsinghua University | And 2 more authors.
Dianwang Jishu/Power System Technology | Year: 2013

The main circuit topology of D-STATCOM based on modular H-bridge cell is researched. Compared with traditional three-phase bridge structure, the voltage rating of the researched device is improved with the same rating voltage of semi-conductor switch. A repetitive learning control strategy for D-STATCOM based on three-phase stationary reference frame, in which system voltage phase locked loop is cancelled, is proposed, so it is simple to implement. Current loop control is based on direct current tracking repetitive learning control to make output current possessing good steady state tracking precision and dynamic response performance under the remarkable change of key parameters of main circuit. The feasibility and effectiveness of the proposed control strategy is verified by simulation results of the STATCOM model based on the platform of PSCAD.


Wang Z.,Nanjing University of Aeronautics and Astronautics | Xiao L.,Nanjing University of Aeronautics and Astronautics | Zhao P.,Autonomous Corporation
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2014

High voltage is one of the design difficulties for the DC converters in high voltage direct current (HDVC) systems. Multi-module series and parallel combinations is one of the effective solutions. The composite structure of full-bridge DC transformers and full-bridge DC converters as two kinds of standardized modules was used for a combined input-series output-parallel (ISOP) DC converter where high voltage will be transformed to low voltage. Unlike m the traditional combined ISOP DC converter, a combination of the open-loop and closed-loop control was used in the composite structure. It ensures that the voltage differences of all modules are controlled in a certain range, and will simplify the control method. Based on the analysis of the output characteristics of each module, this paper gave out a voltage-sharing design of the combined ISOP DC converter. An ISOP simulation model and a principle prototype consisting of two full-bridge DC transformers and one phase-shifted full-bridge series resonant converter were built to verify the effectiveness of the proposed design. © 2014 Chin. Soc. for Elec. Eng..


Wu J.,Guangdong University of Technology | Tang L.,Autonomous Corporation
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

A stochastic scheduling model for hydrothermal power systems was presented based on fuzzy chance constrained programming, taking load demand for a random variable. An impact of load uncertainty on power output, energy consumption and emission of generators was carried out. The random variable of load demand was introduced into all objective functions and constraints. A stochastic scheduling model of hydrothermal power systems was converted into a determined form using fuzzy chance constrained programming and random chance constrained programming. A system with 8 cascaded plants and 6 coal-fired plants is taken for a study example, and a simulation with satisfactory results is carried out to illustrate the accuracy and feasibility of the proposed stochastic scheduling model of hydrothermal power systems with stochastic load. © 2012 Chin. Soc. for Elec. Eng.


Wu J.,Guangdong University of Technology | Tang L.,Autonomous Corporation
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2011

A stochastic scheduling model for hydrothermal power systems is presented based on fuzzy chance constrained programming, taking reservoir inflow and water level for a random variable. Reservoir water volume at the initial hour was formulated as a triangular fuzzy number, representing forecasting errors of reservoir water level. Aiming to represent stochastic variable characteristics due to historical data errors, fuzzy stochastic variables were used to represent the uncertainties incurred in optimization scheduling of hydrothermal power systems. A control function was introduced to coordinate the three objective functions, which includes coal consumption minimization, reservoir water level maximization and air pollutant emission minimization. A stochastic scheduling model of hydrothermal power systems can be converted into a determined form using fuzzy chance constrained programming and random chance constrained programming. A system with 8 cascaded plants and 6 coal-fired plants was taken as a study example and the results show that the model is correct. © 2011 Chinese Society for Electrical Engineering.


Gao X.,North China Grid Company | Xie X.,Tsinghua University | Wu T.,China Electric Power Research Institute | Guo X.,Autonomous Corporation | Wang Z.,North China Grid Company
Dianwang Jishu/Power System Technology | Year: 2012

According to practical experiences and based on the demands of practical projects, several important aspects of subsynchronous resonance (SSR), namely the delicate modeling of generator shaft, fixed series capacitor, supplementary excitation damping control (SEDC) and the real-time digital simulation (RTDS) of SSR, are researched in detail to make them suitable to the accurate analysis on modal stability, transient torque and fatigue life loss when the target system suffers large disturbances. The improved simulation method is applied to actual series-compensated power transmission. By means of simulation analysis on a SSR under short-circuit fault occurred in sending system of Shangdu power plant and the comparison of simulation results of SSR with its actual measured data, the applicability, accuracy and effectiveness of the proposed method in the SSR analysis for actual engineering are verified. It is the first time to adopt the comparative analysis between the simulation results of post-fault SSR and its actual measured data home and abroad, therefore the proposed method possesses reference value.

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