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Yao J.,Chongqing University of Technology | Li H.,Hunan Electrical Power Research Institute | Chen Z.,University of Aalborg | Xia X.,Chongqing University of Technology | And 3 more authors.
IEEE Transactions on Power Electronics | Year: 2013

This paper presents an enhanced control method for a doubly fed induction generator (DFIG)-based wind-power generation system with series grid-side converter (SGSC) under unbalanced grid voltage conditions. The behaviors of the DFIG system with SGSC during network unbalance are described. By injecting a series control voltage generated from the SGSC to balance the stator voltage, the adverse effects of voltage unbalance upon the DFIG, such as stator and rotor current unbalances, electromagnetic torque, and power pulsations, can be removed, and then the conventional vector control strategy for the rotor-side converter remains in full force under unbalanced conditions. Meanwhile, three control targets for the parallel grid-side converter (PGSC) are identified, including eliminating the oscillations in the total active power or reactive power, or eliminating negative-sequence current injected to the grid. Furthermore, a precise current reference generation strategy for the PGSC has been proposed for the PGSC to further improve the operation performance of the whole system. Finally, the proposed coordinated control strategy for the DFIG system with SGSC has been validated by the simulation results of a 2-MW-DFIG-based wind turbine with SGSC and experimental results on a laboratory-scale experimental rig under small steady-state grid voltage unbalance. © 2013 IEEE.

Sheng K.,Hunan Electrical Power Research Institute | Xun X.,Hunan Electrical Power Research Institute
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2015

First, the causes of a safety accident induced by a mistake in the set-up of the distributed control system (DCS) are analyzed, and a model for steam turbine governing system is developed. Then the whole accident is reproduced by a real-time simulation platform. Furthermore, a single machine infinite bus system based on PSASP is used to study and analyze the possibility of forced power oscillation due to DCS at the moment. Research results show that the fault of DCS may trigger forced power oscillation in the power system, and the operating period of DCS has an important influence on forced power oscillation amplitude. ©2015 Automation of Electric Power Systems Press

Zhou Z.,Hunan Electrical Power Research Institute | Bing F.,Hunan Electrical Power Research Institute | Tao W.,Hunan Electrical Power Research Institute | Song X.,Hunan Electrical Power Research Institute
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2012

2,6-Di-tert-butyl-4-methylphenol (BHT), also known as 2,6-di-tert-butyl-p- cresol (DBPC), is an antioxidant widely used in transformer oil. The electrochemcial properties of BHT in transformer oil were investigated by using electrochemical techniques, and a new determination method of BHT in transformer oil based on differential pulse voltammetry was established. It was confirmed that the intensity of characteristic peak of differential pulse voltammetric corresponded for BHT exhibited a good linear relationship with the concentration of BHT within the concentration range from 0.01 to 0.5 %. After researching the accuracy of the experimental results by using spectrophotometry, liquid chromatography, and the electrochemical method, it was further demonstrated that the electrochemical method could be applied to the determination of the content of BHT antioxidant in transformer oils. © 1994-2012 IEEE.

Zhu X.-X.,Hunan Electrical Power Research Institute | Sheng K.,Hunan Electrical Power Research Institute | Liu L.-J.,Datang Huayin Zhuzhou Power Company Ltd
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

Based on Matlab/Simulink, the software for intelligent parameter identification of steam turbine and its governing system is developed, in which polynomial fitting, least square method, the simplex method, genetic algorithm, simulated annealing algorithm are applied. The pretreatment for the original data, intelligent extraction of actuator parameters identification sample, and intelligent processing of boundary conditions of load test data are performed automatically with this software. Furthermore, this software uses several algorithms to identify parameters, and selects the final results according to the preset logic. The simulation and verification results show that the parameters identified by this software can reflect the characteristics of actual steam turbine and its governing system. Finally, the key factors which influence the accuracy of the parameter identification are also indicated.

Wu J.,Hunan Electrical Power Research Institute | Wen J.,Huazhong University of Science and Technology | Sun H.,Huazhong University of Science and Technology | Cheng S.,Huazhong University of Science and Technology
IEEE Transactions on Power Systems | Year: 2012

This paper studies the feasibility of segmenting large power system interconnections with AC link using energy storage technology, similar to the DC link, for improving the system dynamic stability. Firstly, the segmentation validity of the AC interconnected power system using energy storage technology is proved in terms of theoretical analysis, and then a simple and effective control strategy is proposed. Moreover, the influences of the energy storage device location and capacity on the proposed method are discussed in detail. The effectiveness of the proposed method for large AC interconnected power system segmentation is verified by simulations in two AC interconnected power systems. © 2012 IEEE.

Xie G.-S.,Hunan Electrical Power Research Institute | Ouyang K.-J.,Hunan Electrical Power Research Institute
Vibroengineering Procedia | Year: 2015

Transmission line stress directly affects the tower sag force structure and a safe distance from the safe operation of the transmission lines play a crucial role. Calculation method for the preparation of the design process were complied, simply enter transmission liner parameters can be automatically obtained stress and sag. According to a 500 kV transmission line tests carried out stress sag design verification, checking ground found stress design errors and were corrected to ensure the safety of the project. Calculation program can be developed for different voltage levels for line stress on cables sag design verification. © JVE International Ltd.

He Y.-Q.,Hunan Electrical Power Research Institute
China International Conference on Electricity Distribution, CICED | Year: 2012

A novel network model and a fast algorithm for electrical distribution system (EDS) reliability evaluation considering the random energy output of wind power generators (WPG) are presented in this paper. Firstly, a Switch-Section network model is proposed according to the failure isolation characteristics of switches, and then the Switch-Section network is divided into two kinds of parts, main-network and branch-network, based on the property of the power flow direction when WPG are unavailable. Secondly, the concept of energy influence domain (EID) is proposed in order to consider the random wind energy impact on the power supply range of WPG. Based on this concept, we construct the power supply order which successfully implemented the mapping between the random output of WPG and the supply probability to the sections in the EID. Finally, the reliability indices of the main-network and branch-network are calculated by using properties of elements in upstream and downstream fault propagation. Meanwhile, the impacts of WPG on the sections of its EID are considered when computing the nodal downstream reliability indices. The application of the proposed method to the RBTS-BUS6 demonstrates its validity. And the impacts of the position, load demand characteristics, rated capacity of WPG and wind speed on system reliability are also discussed in detail in this paper which will provide some constructive suggestions to WPG installation. © 2012 IEEE.

Ren Z.,Hunan Electrical Power Research Institute | Yu K.,Huazhong University of Science and Technology | Xin Q.,Huazhong University of Science and Technology | Pan Y.,Huazhong University of Science and Technology
IEEE Transactions on Industrial Electronics | Year: 2013

This paper presents the performance of homopolar inductor alternator (HIA) with diode-bridge rectifier and capacitive load. According to the conduction and commutation rules, all the operational modes included in the bridge rectified capacitive load are considered. A simplified average-value mathematical model is established; furthermore, we derive the load characteristic under every operation mode. Using the fundamental machine differential equations and the connecting characteristics between alternator and rectifier, we establish a port-network state model of the system. The performance of the HIA with bridge rectifier and capacitive load can be predicted from charging current, commutating angle, and given parameters of the alternator. Theoretical results are compared with the simulation results obtained from numerical procedure. © 1982-2012 IEEE.

Lu J.,Hunan Electrical Power Research Institute | Zhang Y.,Hunan Electrical Power Research Institute
Gaodianya Jishu/High Voltage Engineering | Year: 2012

Because of the multi-splitting of the 500 kV lines, conventional AC de-icing techniques can not provide enough current for de-icing. For the deicing of 500 kV transmission lines, we presented a high-voltage and high-current DC de-icing method based on 12-pulse rectification by multilevel voltage regulation. Moreover, a combinable DC output voltage method was used according to the variety of transmission line length. Mathematical theory analysis and the system simulation indicated that the method could fulfill de-icing demands of different lengths of 500 kV line. According to the parameters of 500 kV lines of a transformer substation in Hunan, a high-power DC de-icing device based on the proposed method for de-icing 15~50 km of 500 kV line was developed and tested in-field on 500 kV transmission lines. The test results show that the test waveforms are in accordance with the simulation waveforms, validating that the model simulation and theory analysis are correct; the conductor temperature obviously rises from 31.3°C to 42.9°C, and the operation of DC de-icing device is normal. Thus the presented method and device can provide high current for ice melting of 500 kV multi-splitting lines which have obvious a thermal effect of current, and provide a solution for icing UHV lines.

Liao G.,Hunan Electrical Power Research Institute | Xie X.,Hunan Electrical Power Research Institute | Hou Y.,Hunan Electrical Power Research Institute | Xu C.,Hunan Electrical Power Research Institute
Dianwang Jishu/Power System Technology | Year: 2012

According to the planned data of Hunan power grid for the year of 2015, the influence of transmitting power via ±800 kV HVDC transmission line from Jiuquan to Hunan power grid on transient voltage stability of Hunan power grid is simulated by power system analysis software package (PSASP). Simulation results show that under the power transmission from Jiuquan to Hunan via ±800 kV HVDC transmission line the number of being operated generating units in Hunan power grid as well as the capacity of switched over capacitor banks are reduced correspondingly, however the reactive power loss of 500 kV electromagnetic looped network in East Hunan will increase, and after the disturbance the ±800 kV HVDC system will absorb large amount of reactive power from 500 kV electromagnetic looped network in East Hunan, thus the ability of voltage recovery of Hunan power grid after the disturbance will be weakened and the transient voltage stability level of Hunan power grid will be decreased.

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