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Synergistic utilization of coal and other energy- key to low carbon economy

能源前沿 2011年第1期5卷 1-19页

作者： Weidou NI Zhen CHEN State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal EngineeringTsinghua UniversityBeijing 100084China

In China, coal is a dominant component of energy mix, and it is expected to remain as such over the next 30 to 40 years. Coal is expected to be used even more in power generation. The direct combustion of coal already has been causing severe pollution and ecological degradation, and it is quite difficult to address the need to reduce greenhouse gas (GHG) given the direct combustion of coal. Therefore, the polygeneration system based on coal gasification, which is one of the major examples of synergistic utilization of coal, is proposed. It is a comprehensive solution to meet the energy challenges China is facing. Furthermore, the synergy of fossil fuels (especially coal) with renewable energy, the synergy of different kinds of energy for energy storage, the synergy of centralized and distributed supply of different kinds of energy, and the synergy of different kinds of energy in smart energy grid (power, gas, heat, and water) are the keys to making China a low-carbon economy. Carbon dioxide (CO2) mitigation in China should begin from the coalchemical industry given their accumulated relevant experiences. The mitigation process should gradually be transformed into the 'IGCC + polygeneration + CCUS'.The objectives of this paper are to describe the synergistic utilization of coal, and to analyze the synergy of coal with other energy resources, and to propose the scientific and technological problems to achieve these synergies.

关键词： synergy clean and efficient utilization of coal coal-based polygenration CO2 mitigation energy storage

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Detection for voltage fluctuation and flicker calculation based on the instantaneous reactive power theory

Detection for voltage fluctuation and flicker calculation ba...

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International Conference on power Electronics systems and Applications (ICPESA)

作者： Wang, Jidong Liu, Kun Gao, Yanjing Yang, Guanqing Che, Yanbo Key Laboratory of Power System Simulation and Control Tianjin University Ministry of Education Tianjin China

ISBN: (纸本)9781457702051

The voltage flicker which might bring out lighting equipments glitter and images distortion, make people's visual fatigue and adversely affect people's daily lives is caused by the great increase of shocking and nonlinear loads in the power system. In this paper, the causes, detection and measurement of the voltage fluctuation and flicker are analyzed, instantaneous reactive power theory detection method is used for simulation of voltage fluctuations and calculation of short-time flicker value and compared with square detection. The flicker values obtained by instantaneous reactive power theory detection are close to the real value, and the result of simulation shows the effectiveness of this method. © 2011 IEEE.

关键词： Reactive power

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A grid-connection control scheme of PV system with fluctuant reactive load

A grid-connection control scheme of PV system with fluctuant...

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International Conference on Electric Utility Deregulation and Restructuring and power Technologies

作者： Li, Bin Tian, Xiaohe Zeng, Hongyan Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin China

ISBN: (纸本)9781457703638

The fluctuations of reactive load in micro-grid will have a great impact on the supply voltage. In this paper, a novel grid-connection control is proposed in view of this problem, based on a model of a PV system with load paralleled in large system. It can not only make full use of photovoltaic power, but also maintain a stable voltage with a fluctuant reactive load. It adopted double-loop principle in inverter control. The grid-connected current of the PV system and the current of large system are both decoupled into active and reactive component by abc/dq0 transformation to achieve the independent control of active and reactive power. On the one hand, the active component of the PV grid-connected current is adjusted to the reference value given by the Maximum power Point Tracking (MPPT) in order to maintain maximum active power output of PV, the reactive component of the large system current is adjusted in order to maintain a constant reactive power output. Thus a stable supply voltage can be maintained with a fluctuant reactive load, as the supply voltage of the grid-connected PV system is mainly sustained by the large system. On the other hand;the main circuit topology of three-phase reactive power compensation device and three-phase grid-connected inverter is exactly the same. Thus, in support of a reasonable control strategy it can be integrated together with both function of grid connection and reactive power compensation control. These can ensure a stable voltage in the PV system with a fluctuant reactive load paralleled in large system by the regulation of power. Its advantages compared with the simple and traditional unity-power-factor inverter control scheme are validated by simulation with Matlab/Simulink. © 2011 IEEE.

关键词： Reactive power

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Harmonic analysis method based on multiple modulation zoom analysis and interpolating windowed FFT method

Harmonic analysis method based on multiple modulation zoom a...

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International Conference on power Electronics systems and Applications (ICPESA)

作者： Wang, Jidong Yang, Guanqing Wen, Jing Zhu, Dong Che, Yanbo Key Laboratory of Power System Simulation and Control Ministry of Education Tianjin University Tianjin China

ISBN: (纸本)9781457702051

Since many power electronics equipments and nonlinear loads were accessed, more and more harmonics and inter-harmonics occurred in power system. But when the analyzed signal contains components with frequency close to each other, precise analysis can not be made by traditional harmonics analysis methods such as interpolating windowed FFT method. In this paper, first a new method-multiple modulation zoom analysis based on complex analytic bandpass filter is adopted to make an accurate analysis to this kind of components. Then the remaining components are also analyzed by traditional method. simulations compared to direct interpolating windowed FFT method show that the proposed method can make a much better analysis with higher frequency resolution and so effectiveness of this method is demonstrated. © 2011 IEEE.

关键词： Harmonic analysis

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A study on capacity of distributed generation and its effect on short circuit current at micro-grid operation mode

A study on capacity of distributed generation and its effect...

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International Conference on Electric Utility Deregulation and Restructuring and power Technologies

作者： Qiang, Jin Shuo, Zhang Yong-Li, Li Key Laboratory of Power System Simulation and Control Ministry of Education Tianjin University Tianjin China

ISBN: (纸本)9781457703638

Now more and more distributed generations will be connected to distributed power system. It's found that different distributed generation has its own operation characteristic such as fluctuation and uncertainty. When micro-grid is to be island the voltage and frequency will change, so different control modes have been used on different distributed generation. Different kinds of distributed generation have different behavior when system operates normally or fault occurs. Classification and equivalence were adopted to deal with all kinds of the distributed generations in system. The distributed generations with same control mode can be combined to an equivalent generation. When system operates on grid-connection mode the short circuit current relies on the capacity of grid so it is rather large for the capacity of distribution grid is much more than that of distributed generations. But when micro-grid operates on island mode the short circuit current may decrease to a relative small value. Over current protection is widely used in distribution system, and the performance of it is dependent on operation mode, so the value estimate of short circuit current is necessary for verification of credibility and selectivity. Two summations of capacity were proposed to estimate the minimum and maximum short-circuit current in island. © 2011 IEEE.

关键词： Distributed power generation

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Cooperative grid modeling for interconnected multilevel multi-area power systems

Cooperative grid modeling for interconnected multilevel mult...

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International Conference on Electric Utility Deregulation and Restructuring and power Technologies

作者： Jia-An, Zhang Na, Zhang Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin 300072 China

ISBN: (纸本)9781457703638

With the formation of large-scale interconnected power systems, the grid structure and operation mode are becoming increasingly complicated. Currently, the power network model is maintained by distribution centers respectively according to the scope of jurisdiction. For power system analysis, the model data of the whole network is necessary, while only the internal data is transparent to a distribution center and the external data is not accessible directly. Therefore, the model data from distribution centers must be integrated in a high-level distribution center. Such a traditional approach cannot meet the efficiency requirements for large power grid analysis. This paper presents a method of network data modeling and maintenance for multi-level multi-area power systems, in which the local model data are maintained in each distribution center, the connection model is maintained in a higher level of distribution center, and all centers work cooperatively. In a distribution center, the graphic modeling tools should be supported and the local model data can be maintained manually or exported from the EMS. In the method, some technologies are considered, such as model data interfacing, version management, model data maintenance, etc. Cooperative modeling is helpful to improve the analysis efficiency and to reduce the burden of model data maintenance for large power grids. © 2011 IEEE.

关键词： Data integration

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Analysis of directional pilot protection on transmission line with wind farm integration

Analysis of directional pilot protection on transmission lin...

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2011 International Conference on Advanced power system Automation and Protection, APAP 2011

作者： Li, Bin Lin, Meng Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin 300072 China

ISBN: (纸本)9781424496198

Increased integration of wind power makes higher demands on the stability and protection of power system. Wind farms are connected to power grid through transmission line. When single-phase fault occurs on the line, positive and negative sequence currents are not equal and are much smaller than zero sequence current. Phase selector based on the theory of current- difference sudden-change may mistake single-phase fault for phase-to-phase fault because positive and negative branch coefficients are not equal. Considering a case of mal-operation of directional pilot protection, the paper studies the impedance characteristics of asynchronous wind generator, analyzes the causes of weak feed and different branch coefficients, and explains their contribution to fault phase selector's mal-operation. The results are validated by simulation and an improvement for fault phase selection with wind farm integration is proposed. © 2011 IEEE.

关键词： Electric lines

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simulation of shunt active power filter using modified SVPWM control method

Simulation of shunt active power filter using modified SVPWM...

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2011 International Conference on Electric and Electronics, EEIC 2011

作者： Wang, Jidong Yang, Guanqing Liu, Kun Key Laboratory of Power System Simulation and Control Ministry of Education Tianjin University Tianjin 300072 China

ISBN: (纸本)9783642216961

Space vector pulse width modulation (SVPWM) was widely used in inverter control for the advantages of fixed switching frequency, full utilization of DC-link voltage and better control precision. In recent years, SVPWM is gradually applied in the control method of active power filter (APF) as the APF mains is just one invert. The voltage vectors are composed based on the α-β axis in traditional SVPWM however, in this paper one x-y composed reference axis at 60 degree angles from each other is used instead. Compared with traditional method, the principle of the method is relatively simple and easy to implement. At the same time PI regulator is adopted for the DC-link voltage control. Finally simulation results show that the APF has a better compensation effect using this control method. © 2011 Springer-Verlag Berlin Heidelberg.

关键词： Bandpass filters

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Constant voltage control on DC bus of PV system with flywheel energy storage source (FESS)

Constant voltage control on DC bus of PV system with flywhee...

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2011 International Conference on Advanced power system Automation and Protection, APAP 2011

作者： Zhang, HuiZhi Li, YongLi Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin 300072 China

ISBN: (纸本)9781424496198

Fluctuation of the voltage is always the major barrier to the effective application of photovoltaic energy. In this paper, the flywheel energy storage system (FESS) is added to PV system. Considering the fluctuation of photovoltaic energy and limitation of flywheel capacity, flywheel may store energy from the photovoltaic source or AC system, or release energy to load in order to maintain the stable voltage on DC bus. Five different system operating modes and corresponding control strategies are presented in this paper. Corresponding to the different system operating modes, simulation has been done and the control strategies of FESS have been proved valid. © 2011 IEEE.

关键词： Flywheels

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Application of a combined system to enhance power quality in an island microgrid

Application of a combined system to enhance power quality in...

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2011 IEEE power Engineering and Automation Conference, PEAM 2011

作者： Ma, Zhengbo Li, Linchuan Dong, Tuo Key Laboratory of Power System Simulation Control of Ministry of Education Tianjin University Tianjin 300072 China

ISBN: (纸本)9781424496884

Efficient and effective use of renewable energy, distributed generation and energy storage can solve global problems such as energy crisis and climate change. A promising solution to interconnecting these distributed energy resources with the utility grid is the microgrid paradigm. Due to the dispersion of distributed sources and loads, different distributed sources use the different control strategies. Microgrid is usually interconnected with the utility grid by the inverter, which causes to many current harmonics in the export of the inverter. Without the support of the utility grid, the variation of reactive power of the loads in the island microgrid will lead to voltage fluctuation. Under the premise of assuming that the microsource could supply adequate active power to the loads, this paper proposes a combined system constructed by Shunt Active power Filter (SAPF) and Static Var Compensator (SVC) to improve the power quality of the island microgrid, in which SAPF uses the positive sequence method for harmonic detection and uses Hysteresis control method for current tracking control and is adopted near the microsource to mitigate harmonic currents and SVC is set near the load to compensate reactive power so as to relieve the voltage variation. simulation results show the effectiveness of the combined system. © 2011 IEEE.

关键词： Static Var compensators

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