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23rd Annual IEEE Applied power Electronics Conference and Exposition (APEC 2008), vol.2

作者： Zhou Dejia Zhao Zhengming Mohamed Eltawil Yuan Liqiang The State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

In this paper an optimum design and control of three-phase grid-connected PV system has been proposed and analyzed. Also, a developed maximum power point tracking (MPPT) controller that uses the PV array differential power to voltage (dP/dV) as an index to provide the reference voltage of maximum power point (MPP) quickly and accurately is presented. The control scheme of a three phase current-controlled space vector pulse-width modulation (SVPWM) inverter in rotating synchronous coordinate d-q with the proposed MPPT algorithm and feed-forward compensation is discussed. The PV grid-connected system controller employs multi-loop control with the filter inductor current of the inverter in the inner loop to achieve fast dynamic response and the outer loop to control dc bus voltage for MPPT. The design method provided in the paper for the controller parameters and filter proved to be very practical and effective. Both the power quality into the grid and power factor correction comply with standards IEEE 929-2000. Good agreement is obtained between simulation and experimental results which illustrated the high performance of the proposed approach.

关键词： Digital signal processor Grid-connected PWM inverter MPPT Photovoltaic (PV) system PI compensators Unity power factor

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Research on the prediction-model of the surface-temperature of large oil-immersed power transformer

Research on the prediction-model of the surface-temperature ...

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International Conference on Electrical Machines and systems (ICEMS)

作者： H.Y. Wang P.S. Su X.H. Wang Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

In order to detect the abnormal temperature of large oil-immersed power transformer earlier, this paper presents a new prediction-model of surface-temperature for the transformer to predict the normal surface-temperature. And to compare the difference between the predicted value and the measured value can judge if the condition of the transformer is fit to operate. The model parameters are estimated from the field data by using the partial-least-square method, which overcomes the instability of results estimated by using the traditional least-square method. Furthermore, the appropriate amount of data for the parameter estimation was decided according to the principle of heat transfer and the characteristics of the predicted deviation, such as mean, variance and normal distribution. The prediction model is verified from the accuracy of results predicted with one year of field data.

关键词： power transformers Oil insulation Temperature sensors Predictive models Parameter estimation Heat transfer Temperature measurement Thermal resistance power system simulation Surface fitting

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Analysing on characteristics of lightning shielding failure of UHVAC double circuit transmission line based on leader progression method

Analysing on characteristics of lightning shielding failure ...

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Asia-Pacific Symposium on Electromagnetic Compatibility (APEMC)

作者： Zhiyong Wang Shaoan Wang Zhanqing Yu Yinan Geng Rong Zeng Jinliang He Zhizhao Li Guangzhou Power Supply Bureau China Southern Power Grid Company Limited Guangzhou China Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781424456215

Shielding failure of lightning is the key problem for safe operation of UHV transmission lines. Taking the feature of 1000KV AC double circuit transmission lines into account, the leader progression method with proper criterion was employed. The lightning shielding failure rate of top phase, middle phase and bottom phase of two different transmission line tower types were compute, in three different geography conditions. The research work is helpful for improving the lightning performance of UHV transmission lines.

关键词： Failure analysis Lightning Distributed parameter circuits Conductors power transmission lines Transmission line theory Voltage Corona Poles and towers power system simulation

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Calculation on the thermal field of the water cooling stator of three-Gorge hydro-generator

Calculation on the thermal field of the water cooling stator...

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International Conference on Electrical Machines and systems (ICEMS)

作者： H.Y. Wang P.S. Su X.H. Wang Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

To simplify the calculation of winding bar temperature for the condition monitoring of the water cooling stator of Three-Gorge hydro-generator, this paper calculates three of two-dimension thermal fields. Using the three fields simulates the different section along the axial direction of the generator. The total amount of heat taken away by water can be calculated by weighting the result of three fields on the total axial length of them. Four groups of thermal-fields with different outlet-water temperature are calculated by using ANSYS multi-physical software. The calculation results of temperature of measurement-point between up-layer and down-layer bars in stator are partly supported by the measurement data. And the relatively error between the heat taken by cooling-water and the heat generated by the stator bar is always less than 5%

关键词： Cooling Stator cores Stator windings Solids Bars Heat transfer power system simulation Temperature Thermal engineering Condition monitoring

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Dual-Timescale control for power Electronic Zigzag Transformer

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CES Transactions on Electrical Machines and systems 2017年第3期1卷 315-321页

作者： Chunpeng Zhang Zhengming Zhao State Key Laboratory of Control and Simulation of Power System Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijing100084China

power electronic zigzag transformer is an attractive solution for the flexible interconnection of smart distribution *** is constituted by slow-response and low-precision thyristor converters and fast-response and high-accuracy voltage source *** paper models its primary circuit and addresses its basic operation *** a dual-timescale control scheme is investigated to realize the coordinated regulation of both types of converter.A simulation case is established in PSCAD containing interconnected mid-voltage distribution *** with poor-and well-matched control timescales are both carried *** accordingly,the power flow controllability under these conditions is *** the shorter control timescale is no more than tenth of the longer one,the power electronic zigzag transformer will operate with satisfying performances.

关键词： power electronic transformer thyristor converter voltage source converter dual-timescale control flexible interconnection

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Short-term power Prediction Based on Improved NWP Data Considering Wind Speed Distribution Inner Wind Farm

Short-term Power Prediction Based on Improved NWP Data Consi...

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IEEE Conference on Energy Internet and Energy System Integration (EI2)

作者： Wei Ma Ying Qiao ZongXiang Lu ZhiFeng Liang JiaMing Li YuChen Hao State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments of Electrical Engineering Tsinghua University Beijing China State Grid Corporation of China Beijing China State Grid Jiangsu Power Grid Corporation Nanjing China

The wind farm has only one NWP data point, which cannot accurately reflect the wind resources inside the wind farm. To solve the problem of a poor match between short-term wind power prediction numerical weather forecast and wind farm measured weather. Put forward a kind of based on clustering and temporal characteristics of the modified liters of scale wind power prediction method, first of all, using EOF orthogonal decomposition method to extract the features of each fan, using hierarchical analysis method of the characteristics of the data matrix clustering, and then, each cluster sample selected representative of a fan, using the error transfer characteristic of the NWP data sequence is modified. Finally, The CNN prediction model is used for power prediction, and the weight is determined according to the cluster sample size. A wind farm in northern Hebei, China, is used to verify the effectiveness of the proposed method.

关键词： Fans Wind speed System integration Wind farms Wind power generation Predictive models Feature extraction

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The influence of wind on the audible noise of ultra HVDC transmission line in high altitude area

The influence of wind on the audible noise of ultra HVDC tra...

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Asia-Pacific Symposium on Electromagnetic Compatibility (APEMC)

作者： Min Li Rong Zeng Dawei Yang Zhanqing Yu Ruihai Li Lei Liu Bo Zhang Huaying Zhang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China Technology Research Center China Southern Power Grid Company Limited China

ISBN: (纸本)9781424456215

The corona performance and the electromagnetic environment of the transmission system has become a crucial issue that has been taken into consideration in the line design, and among which audible noise (AN) is one of the most important factors. The wind in the high altitude area is mostly strong, and could greatly influence the AN. This paper, based on the high altitude HDVC test line, studied the characteristics of AN generated by the transmission line, and analyzed the influence of wind velocity and wind direction on the AN lateral profile.

关键词： Acoustic noise HVDC transmission Testing Wind speed Corona power transmission lines Microphone arrays Voltage Electromagnetic compatibility power engineering and energy

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Tests on electromagnetic environment of ultra HVDC transmission lines in high altitude region

Tests on electromagnetic environment of ultra HVDC transmiss...

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Asia-Pacific Symposium on Electromagnetic Compatibility (APEMC)

作者： Zhanqing Yu Rong Zeng Min Li Ruihai Li Lei Liu Bo Zhang Zheng Zhang Huaying Zhang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China Technology Research Center China Southern Power Grid Company Limited China

ISBN: (纸本)9781424456215

The Ultra High Voltage DC power transmission technique is developed quickly in China but used barely in the world. Corona phenomenon in high altitude region is more serious, and corresponding electromagnetic environment is more severe as well. A UHVDC test lines are completed for tests in Kunming, China, with an altitude of 2100 m. An automotive electromagnetic environment testing system was installed under the line. Measurement of electromagnetic environment was carried out. Radio interference, audible noise, resultant electric field and ion current density at ground level were measured at different voltage from ±800kV to ±1000kV, and atmosphere conditions including sunny, rainy and cloudy weather. The measured result show some difference with those acquired at sea level and is significant for further studies of corona mechanism under high altitude condition. Measured results were compared with the calculated results.

关键词： HVDC transmission Atmospheric measurements Sea measurements Electromagnetic measurements Voltage Corona power transmission Automotive engineering System testing Electromagnetic interference

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Rotor End Factors for 2-D FEA of Induction Motors with Smooth or Slitted Solid Rotor

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CES Transactions on Electrical Machines and systems 2017年第2期1卷 132-139页

作者： Shanming Wang Ziguo Huang Yuguang Sun Haixiang Cao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

Modifying the equivalent rotor resistivity with rotor end factor in 2-dimension(2-D)finite element analysis(FEA)is an effective way to analyze the 3-dimension(3-D)solid rotor *** the smooth solid rotor,five different rotor end factors are discussed and compared with each *** is theoretically clarified that the resistivity of rotor in 2-D FEA should be multiplied by the square of rotor end factors to take the 3-D end effect of solid rotor into *** the slitted solid rotor,an improved rotor end factor is proposed based on the equivalent area algorithm of eddy currents in rotor,since the end factors of smooth solid rotor are not ***,the time-harmonic finite element method(FEM)combined with the rotor end factor is applied to analyze the performance of solid rotor induction *** tested and computed results are in good agreement,which proves the effectiveness of rotor end factor for the simplication of 3-D solid rotor problems.

关键词： Eddy currents FEA rotor end factor solid rotor time-harmonic field

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Optimized design of main protection configuration scheme for internal faults of Shawan generator

Optimized design of main protection configuration scheme for...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Yuguang Sun Xiangheng Wang Lin Gui Weijian Wang Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)7506274078

In order to provide high-quality protection for large- and medium-sized generators, a new feasible method of designing main protection configuration scheme for internal faults of generators is desirable. Based on calculation of all the possible internal faults with the multi-loop method, the optimized design method is illustrated through Shawan generator in this paper. With this method, the optimal protection configuration scheme, composed of the split-phase transverse differential protection, two sets of incomplete longitudinal differential protection as well as one set of single element transverse differential protection, is determined for the internal faults of Shawan generator, which has two branches in each phase. The rate of operation and double-protection of the optimal scheme both reach the maximum. In addition to that, on all the possible phase-to-phase faults, at least two kinds of protection of the optimal scheme are sure to operate correctly. The optimized scheme excels the conventional one in protection performance index, which verifies the validity of the optimized method of designing main protection configuration scheme for generators.

关键词： Design optimization Circuit faults Design methodology power generation power system protection Character generation power system simulation Performance analysis Stators Sun

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