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Chinese control Conference (CCC)

作者： Wei Wei Shengwei Mei Feng Liu State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing Beijing CN

With the rapid development of renewable energies, especially wind power, how to manage unexpected generation variations economically and reliably in dispatch has become crucial for modern power systems. To address this issue, this paper presents an affine disturbance feedback robust dispatch (ADF-RD) methodology for power systems with large scale wind power integration in the framework of adjustable robust optimization (ARO). This methodology divides the dispatching process into pre-dispatch and re-dispatch. Pre-dispatch decision immunizes against all possible realizations of uncertainties in a set, while re-dispatch which can be regarded as a feedback will be adaptively adjusted using an affine function with respect to the realized uncertainty in real time. The ADF-RD methodology is applied to an hourly ahead dispatch (HAD) problem. The effectiveness and efficiency of the proposed ADF-RD methodology are demonstrated by numerical experiments carried on a five-bus system.

关键词： Uncertainty Wind power generation Wind forecasting Wind farms Load flow power transmission lines

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A massive grid-connected power accumulator battery testing system using hybrid AC-DC microgrid

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Diangong Jishu Xuebao/Transactions of China Electrotechnical Society 2014年 29卷 449-453页

作者： Long, Bo Sun, Hongbin Wang, Bin Yao, Shuqing Fang, Xu Yao, Gaoxiang University of Electronic Science and Technology Chengdu610054 China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing100084 China Bohai New Century Machinery Manufacturing Co. Ltd. TianJin300280 China

Nowadays, the network mode of the most energy recovery power battery testing instruments adopts AC-microgrid, which has the drawbacks of low energy recovery efficiency, complicated power circuit topology, cumbersome of the control algorithms. Aiming at these issues, a hybrid AC-DC microgrid system which is based on the power battery testing system has been put forward in this paper. The proposed scheme is composed by an energy storing system, a bidirectional DC-DC converter for test experiment, the grid-side loads, compared with conventional scheme, the proposed scheme has the merits of higher energy recovery efficiency, simplified power circuit for testing instruments. ©, 2014, Diangong Jishu Xuebao/Transactions of China Electrotechnical Society. All right reserved.

关键词： DC-DC converters

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Surface Partial Discharge Characteristics of Oil-paper Insulation Under Combined AC-DC Voltage

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高电压技术 2013年第8期39卷 1902-1910页

作者： SHA Yanchao ZHOU Yuanxiang NIE Dexin WU Zhirong DENG Jiangang LU Licheng State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Electrical Insulation and Power Equipment Department of Electrical Engineering State Grid Electric Power Research Institute Wuhan 467001 China State Grid Corporation of China Beijing 100031 China

The valve side windings of converter transformers bear AC, DC, impulse, and reversal-polarity voltages during operation, which could result in serious insulation problems of the equipment. By performing experiments with surface discharge model of oil-paper insula- tion at 80 ℃ under combined AC-DC voltage for 200 h, we studied the spectrums and statistical parameters of partial discharges at different discharge stages. Furthermore, some fingerprint parameters were calculated in order to estimate the development situation of par- tial discharge, while the characteristic gases dissolved in the transformer oil were measured by gas chromatography. The surface discharges in the experiments were observed using a high speed camera, and a full discharge process could be marked off into four stages as follows. ①The elementary stage. When a partial discharge occurs near electrodes, electrical charges are injected into the region near electrodes and causing bubble generation. ②Due to their high resistivity and low dielectric constant, the bubbles would bare the major part of the voltage applied to samples. Therefore, discharge happens inside the small bubbles, and it emits a lot of light. ③Micromolecules of gas are produced in discharge, and further ionization in the transformer oil takes place simultaneously when high-energy electrons collide with oil molecules. ④The carrier charge moves forward to electrodes driven by the applied electric field, till they neutralize with the charge from electrodes, and hence discharge channels are formed subsequently.

关键词： AC-DC 放电特性绝缘表面电压油纸油中溶解气体换流变压器合作

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Development and Application of DC Partial Discharge Test system

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高电压技术 2013年第8期39卷 1981-1987页

作者： NIE Dexin SHA Yanchao ZHOU Yuanxiang WU Zhirong DENG Jiangang State Grid Electric Power Research Institute Wuhan 430074 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

Direct current (DC) partial discharge (PD) test has drawn extensive attention from world-wide electric power research institutes in recent years. However, presently, no DC PD detection device on the market has the statistical function. Thus, we developed a test system for PD detection under DC voltage, which is characterized by strong anti-jamming capability, continuous high-speed real-time data acquisi- tion and effective, complete detection of DC PD signals. The DC PD mechanism, as well as the measuring principles, software system, and hardware design of the test equipment were introduced. Adopting typical electrode pairs, we tested the statistical spectrum of PD under DC voltage. The main difference in statistical spectrums between parallel plate electrodes and needle-plate electrodes was that the time interval between two consecutive discharges for needle-plate electrodes has obviously larger variation range than that for parallel plate electrodes, which could be the convincing proof for distinguishing the type of electrodes under DC PD. Practical results indicate that the proposed sys- tem can measure time domain signals of DC PD of oil-paper insulation effectively and promptly, and it can be used to determine and detect defects in DC power transmission equipment.

关键词：局部放电信号直流电压测试系统开发针板电极应用检测装置实时数据采集

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Comparison of two basic structures in magnetically-coupled resonant wireless power transfer

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Diangong Jishu Xuebao/Transactions of China Electrotechnical Society 2013年第SUPPL.2期28卷 18-22页

作者： Zhang, Yiming Zhao, Zhengming Yuan, Liqiang Lu, Ting State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing 100084 China

Wireless power transfer (WPT) has been a research focus in recent decades. Based on magnetically-coupled resonant WPT (MCR-WPT), this paper made a comparison of two basic structures in MCR-WPT: the two-coil structure and the four-coil structure. Their equivalent circuits were built. To illuminate the difference between these two structures, the input impedance, the transfer efficiency, and the load matching were studied and tested by experimental results. The conclusion is drawn that without reducing the transfer efficiency, the addition of the source coil and the load coil in the four-coil structure makes it easier to match the source and the load than the two-coil structure.

关键词： Magnetic resonance

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Numerical Analysis of Space Charge Characteristics in Low-density Polyethylene Nanocomposite under External DC Electric Field

Numerical Analysis of Space Charge Characteristics in Low-de...

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中国物理学会第十八届全国静电学术会议

作者： ZHOU Yuanxiang ZHANG Ling SHA Yanchao TIAN Jihuan State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University ABB (China) Limited Universal

In this work, we are interested in space charge dynamics characteristics in the low-density polyethylene(LDPE) nanocomposite mixed with some mass fraction of inorganic nanofillers. Different with all previous qualitatively theoretical works, numerical simulation based on the bipolar charge transport model was performed to systematically investigate the influence of trap depth, trap concentration, and injection barrier height on the space charge and electric field distributions under DC external electric field of 100 k V/mm. Our simulation results showed that increasing the trap depth would severely distort the electric field distribution at the balanced status with the highest and lowest electric field of 119 k V/mm and 47 k V/mm, respectively. Due to the introduction of nanofillers, more deep traps were created and blocked the space charge movement, capturing most of space charge in the vicinity of the electrode and largely declining the local electric field further. In addition, our theoretical analysis also showed both the high permittivity and low local electric field contributed to the increase of injection barrier height. Once the injection barrier height surpassed 1.25 e V, there was almost no charge that could overcome the injection barrier. At last, a mechanism of space charge suppression in the LDPE nanocomposite was presented.

关键词： LDPE nanocomposite space charge bipolar charge transport model trap depth Schottkyinjection barrier height

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Resistance Characteristics of Arc in Long Air Gap

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高电压技术 2013年第8期39卷 1881-1885页

作者： YU Zhanqing YU Junjie ZENG Rong CHEN He PENG Xiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Maintenance and Test Center of EHV Power Transmission Company China Southem Power Grid Co. Ltd. Guangzhou 510663 China

Arc resistance is an important parameter for characterizing long arcs in air, and its laboratory testing is of importance for accurate arc modeling of electromagnetic transient caused by short circuit fault. Therefore, we constructed an experimental system to study the cha- racteristics of long AC arc in air. Driven by currents of 10 kA or 40 kA (root mean square value), the system produces arcs with different initial lengths of 1 m, 2 m and 4 m, and the movement of the arcs are captured by a high-speed camera. After performing experiments using the system, we carried out analysis and comparisons of the arc resistance of arcs with different lengths and different currents, as well as a study of the relationship between the macro-morphology and the resistance of the arcs. Conclusions were drawn from the experimental re- sults: the arc voltage had obvious saturation characteristics; the arc resistance increased with the increase of arc length and the decrease of current; the arcs bended or extended significantly in time and the peak arc voltage within a single cycle increased correspondingly; the arcs had voltage and current in the same phase. In the end, a formula of arc resistance based on the experiment results is derived.

关键词：耐电弧性电阻特性空气间隙实验室测试电流驱动实验系统初始长度电弧电压

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Research on platform for advanced control of energy storage system

Research on platform for advanced control of energy storage ...

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2nd IET Renewable power generation Conference (RPG 2013)

作者： Hanchen Xu Zhichang Yuan Chao Lu Can Wang Haifeng Guo Yongxing Li State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing 100084 China China Southern Power Grid Power Generation Company Guangzhou 510630 China

Advanced applications of energy storage system comprise load shifting, isolated island operation, frequency regulation and reactive support, etc. There are already algorithms and control strategies for advanced applications, but still lack an independent supporting software platform. This paper concentrates on the structure and realization of software platform for advanced application of large-scale energy storage system, including demand analysis, software architecture and module design, user interface and functionality development. An easy to operate and expand software platform, with a beautiful graphical user interface and support for visualization of data, was designed and implemented.

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Analysis of Excitation Characteristics of Ultra High Frequency Electromagnetic Waves Induced by PD in GIS

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高电压技术 2013年第8期39卷 1893-1901页

作者： DING Dengwei GAO Wensheng YAO Senjing LIU Weidong HE Jiaxi Sichuan Electric Power Research Institute Chengdu 610072 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Shenzhen Power Supply Co. Ltd Shenzhen 518001 China

The understanding of the excitation mechanism of ultra high frequency (UHF) electromagnetic waves (EW) is essential for ap- plying UHF method to partial discharge (PD) detection. Since the EW induced by PD in gas insulated switchgear (GIS) contains not only transverse electromagnetic (TEM) wave, but also high-order transverse electric (TE) and high-order transverse magnetic (TM) waves, we analyzed the proportions between the TEM wave and the high order waves, as well as the influence of the PD position on this proportion, using the finite different time domain (FDTD) method. According to the unique characteristics of the waves, they are separated only ap- proximately. It is found that the high-order mode is the main component, more than 70%, of the electric field around the enclosure of GIS, and that with the increasing distance between PD source and inner conductors, the low frequency ( below about 800 MHz) component of EW decreases, but the high frequency component (above 1 GHz) increases, meanwhile the proportion of high-order components in EW could reach 77% from 70%. It concluded that the closer the PD source to the enclosure is, the easier high order EW may be excited.

关键词：超高频电磁波励磁特性 GIS PD 诱导气体绝缘开关设备 UHF方法 TEM波

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Automatic voltage control for ultra-high voltage AC neighboring grids

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Dianli Xitong Zidonghua/Automation of Electric power systems 2013年第21期37卷 99-105页

作者： Wang, Bin Guo, Qinglai Sun, Hongbin Tang, Lei Zhang, Boming Wu, Wenchuan Department of Electrical Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing 100084 China

The connection of ultra-high voltage (UHV) transmission line has brought a challenge to the voltage operation and control of its neighboring power system. Facing engineering practice, this paper proposes an automatic voltage control (AVC) method for the UHV neighboring grids. The reactive voltage operation and control characteristics of UHV neighboring grids are analyzed, including the tremendous impact of UHV active power flow change on the bus voltage in UHV neighboring grids, the large voltage fluctuation, and the tight coupling among power plants and substations, etc. The smart voltage optimal control technology is proposed and implemented by taking into consideration these characteristics and the coordinated control among tightly coupled power plants and substations in the UHV neighboring grids. This method can reduce the irrational reactive power flow and bypass the unnecessary discrete device action, while ensuring voltage security. The proposed method is put into closed-loop field operation in China for its validated efficiency and practicability. ©2013 state Grid Electric power Research Institute Press.

关键词： Smart power grids

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