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6th International Conference on Renewable power generation

作者： Li, Hao Lu, Zongxiang Qiao, Ying Wang, Ningbo Ding, Kun State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China Wind Power Technology Center Gansu Electric Power Corporation Lanzhou730050 China

The prediction method based on the partition of weather types has been widely used in photovoltaic prediction. Here, the temporal characteristics of PV data is studied, the physical meaning of the sequential difference sequences is analysed, and a characteristic index system including sequential characteristics index is proposed. The weather types are partitioned based on self-organising map neural network algorithm. Case study shows that the partition method is helpful to improve the discrimination of weather types and to improve prediction accuracy. © 2017 Institution of Engineering and Technology. All Rights Reserved.

关键词： Weather forecasting

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Ferro-resonance over-voltage and power frequency over-voltage on the neutrals of 220kV power transformer and corresponding protection strategy

Ferro-resonance over-voltage and power frequency over-voltag...

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作者： Yu, Hua-Peng Chen, Shui-Ming Yu, Hong-Qiao Yang, Peng-Cheng Yin, Hua Wu, Gaolin State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Chongqing Electric Power Research Institute Chongqing 401123 China

ISBN: (纸本)9781457700668

In order to limit short-circuit current and satisfy the need of relay setting, only part of the 220kV power transformer is grounded, so on the neutrals of ungrounded transformers will appear the over-voltage. Currently the value of over-voltage on transformer neutral point and the corresponding protection strategy is based on theoretical formula, this article use the PSCAD/EMTDC software to calculate the over-voltage on the neutral point of 4 ungrounded power transformers in Chongqing 220kV power grid, the result shows that the power frequency transient over-voltage on the neutrals may reach 178kV, If the single-phase grounding fault occurs in ungrounded power system, the power frequency over-voltage on the neutrals will be more serious and rise to 138.6kV. Non-full phase operation may cause serious ferro-resonance over-voltage on the neutrals of no-load transformer, which may last for seconds and may rise to 723.7kV, causing serious threat to the transformer neutrals and line-side equipment. The article also studies the gap parameter which should be taken on the neutrals of 220kV transformers at the end. © 2010 Chinese Soc for Elec Eng.

关键词： power transformers

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Direct heuristic dynamic programming method for power system stability enhancement

Direct heuristic dynamic programming method for power system...

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2014 American control Conference, ACC 2014

作者： Yu, Miao Lu, Chao Liu, Yongjun School of Mechanical-electronic and Automobile Engineering Beijing University of Civil Engineering and Architecture Beijing 100044 China State Key Laboratory for Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100084 China Technology Research Centre of China Southern Power Grid Guangzhou 510623 China

ISBN: (纸本)9781479932726

In this paper a neural network-based approximate dynamic programming method, namely direct heuristic dynamic programming (direct HDP), is applied to power system stability control. Direct HDP is a learning and approximation based approach to address nonlinear system control under uncertainty. In the present paper, real-time system responses provided by wide area measurement system (WAMS) are used to construct such controllers which are uniquely tailored for the problems under consideration. In addition, the controller learning objective is formulated as a reward function that reflects global characteristics of the power system low frequency oscillation under the consideration of coupling effect among system components. The contribution of the paper includes a convergence proof of the direct HDP algorithm using an LQR framework, as well as case study to illustrate the proposed learning control algorithm. The case study aims at providing a new solution to a difficult large scale system coordination problem where the China Southern power Grid is used for. © 2014 American Automatic control Council.

关键词： controllers

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Multi-Stage Optimization Model for New power system Based on the Data Mining Algorithm 3

Multi-Stage Optimization Model for New Power System Based on...

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3rd International Conference on Clean and Green Energy Engineering, CGEE 2022

作者： Liu, Jian Liu, Zhijun Zhang, Jiahao Fu, Guanhua Zhu, Lei Zhao, Ergang Hangzhou Power Supply Company State Grid Zhejiang Electric Power Co. Ltd. Hangzhou China Wuxi Research Institute of Applied Technologies Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Dept. of Electrical Engineering Beijing China

ISBN: (数字)9781665452656

ISBN: (纸本)9781665452656

The construction of a new power system with new energy as the mainstay is conducive to accelerating the green transformation of the economy and society and high-quality development. However, in the new power system, the new load spiking characteristics are obvious, and the increase in peak-to-valley difference on the load side will cause a greater impact on the traditional power system. To achieve the goal of building a new power system with new energy as the mainstay, the demand response potential of users needs to be fully explored, and to a certain extent, the demand side will be prompted to provide equivalent regulation resources to the power side, which is of great significance to alleviate the tension between power supply and demand and promote the consumption of renewable energy. Therefore, this paper develops a multi-stage optimization model for new power system based on data mining algorithms. The model is based on a cluster mining method to extract the typical electricity consumption behaviour characteristics of users. Then the demand response potential of multi-cluster customers is analysed and the demand response characteristics of multi-cluster customers are studied. Finally, a multi-stage demand response optimization model under the new power system is established. © 2022 IEEE.

关键词： Renewable energy resources

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Reducing the Impact of Source Internal Resistance by Source Coil in Resonant Wireless power Transfer

Reducing the Impact of Source Internal Resistance by Source ...

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IEEE Energy Conversion Congress and Exposition

作者： Yiming Zhang Ting Lu Zhengming Zhao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781479957774

Wireless power transfer (WPT) is the state-of-the-art research interest. In the WPT system efficiency is an important figure of merit. In order to reduce the impact of the source internal resistance and improve the system efficiency of the conventional two-coil structure, a source coil is added to the two-coil structure, forming a three-coil structure. Both the two-coil structure and the three-coil structure are modeled and analyzed with the circuit theory. The system efficiencies of both structures with optimal loads and a fixed load are deduced. The system efficiency of the three-coil structure is proved to be higher than that of the two-coil structure. An experimental apparatus is implemented and the experimental results match well with the theoretical calculations. The larger the source internal resistance, the more significantly the addition of the source coil improves the system efficiency.

关键词： Coils Wireless communication Resistance Magnetic resonance Integrated circuit modeling Equivalent circuits

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A selection method of mutual inductance identification models based on sensitivity analysis for wireless electric vehicles charging

A selection method of mutual inductance identification model...

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IEEE Energy Conversion Congress and Exposition

作者： Fang Liu Zhengming Zhao Yiming Zhang Kainan Chen Fanbo He Liqiang Yuan State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781509007387

Wireless power transfer has been recognized as a promising technology for electric vehicles charging. However, the parking misalignments between the transmitter coil on the ground and the receiver coil inside the car may cause variations in the mutual inductance for the charging system, which will reduce its transfer power and efficiency. In order to improve the transfer efficiency and optimize the operating condition, it is essential to identify the mutual inductance. In this paper, identification models are studied with and without communication feedback from the receiver coil under two typical cases (resonant transmitter and inductive transmitter). A selection method based on sensitivity analysis is proposed to select models of high accuracy against measurement errors and sampling propagations. simulation and experimental results verify the effectiveness and validity of the proposed method. This work is helpful for evaluating and improving the wireless charging system's tolerance against misalignments as well as optimizing its operation condition.

关键词： sensitivity analysis wireless power transfer (WPT) mutual inductance identification

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Multi-Timescale Trading Strategy for Renewable power to Ammonia Virtual power Plant in the Electricity, Hydrogen, and Ammonia Markets

IEEE Transactions on Energy Markets, Policy and Regulation

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IEEE Transactions on Energy Markets, Policy and Regulation 2023年第4期1卷 322-335页

作者： Wu, Sirui Lin, Jin Li, Jiarong Liu, Feng Song, Yonghua Xu, Yanhui Cheng, Xiang Yu, Zhipeng Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing100087 China Tsinghua University Sichuan Energy Internet Research Institute Chengdu610213 China University of Macau Department of Electrical and Computer Engineering Macau999078 China Tsinghua University Department of Electrical Engineering Beijing100087 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing102206 China

Renewablepower to ammonia (RePtA) is a prominent zero-carbon pathway for decarbonization. Due to the imbalance between renewables and production energy demand, the RePtA system relies on electricity exchange with the power grid. Participating in the electricity market as a virtual power plant (VPP) may help to reduce energy costs. However, the power profile of local photovoltaics and wind turbines is similar to those in the market, resulting in rising energy costs under the conventional strategy. Hence, we develop a multi-timescale trading strategy for the RePtA VPP in the electricity, hydrogen, and ammonia markets. By utilizing the hydrogen and ammonia buffer systems, the RePtA VPP can optimally coordinate production planning. Moreover, we find it possible to describe the trading of electricity, ammonia, and hydrogen in a unified timeframe. The two-stage robust optimization model of the electricity market is extended to multiple markets and solved by the column and constraint generation (CC&G) algorithm. The case is derived from an actual project in the Inner Mongolia Autonomous Region. Sensitivity analysis demonstrates the economic advantages of the RePtA VPP joining multiple markets over the conventional strategy and reveals the necessity of the hydrogen and ammonia buffer and reactor flexibility. © 2023 IEEE.

关键词： Ammonia

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A predictive DC voltage control scheme for back-to-back converters based on energy balance modeling

A predictive DC voltage control scheme for back-to-back conv...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Lu Yin Zhengming Zhao Ting Lu Fanbo He Liqiang Yuan State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

This paper presents a predictive control scheme of DC-link voltage for back-to-back converters based on energy balance modeling. Since the variation of DC-link voltage is affected by the energy mismatch between rectifier and inverter, the energy distribution in a rectifier-inverter is analyzed. Moreover, in order to calculate the input and output energy in one control period accurately, the grid current is regulated by predictive control and the instantaneous active power consumed by the induction motor is estimated. Then, an equation based on energy balance in one control period is established, and the DC-link voltage can be controlled by solving it. Finally, simulation results show that with the proposed control scheme, the back-to-back converter exhibits both good dynamic and steady-state performances.

关键词： Voltage control Induction motors Rectifiers Capacitors Vectors Pulse width modulation Inverters

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DC pre-excitation application in three-phase induction motor drive system

DC pre-excitation application in three-phase induction motor...

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IEEE International Symposium on power Electronics for Distributed generation systems (PEDG)

作者： Sideng Hu Zhengming Zhao Ting Lu Liqiang Yuan Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

Due to the current restriction of semiconductor devices, the start-up is an extremely important process in the ASD (adjustable speed drive) system. DC pre-excitation is one of the effective solutions for increasing the starting torque and depressing the starting inrush current. However the effect of DC pre-excitation would be discounted if it could not be compatible with the induction motor drive control system. Also the stability of the DC pre-excitation application is related to its operational mode. This paper addresses the principle of DC pre-excitation and excavates its relationship with current control. The method to improve the stability of DC pre-excitation effectively shielding EMI is detailed. The relevant study has been implemented in a control system for a 55 kW and 160 kW induction motor and the simulation and experimental results validate the effectiveness of the proposed design method.

关键词： Induction motors Torque DC motors Electromagnetic interference Process control Variable speed drives Switches

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Approaches to enhance discrete control algorithms serving for motor drive system

Approaches to enhance discrete control algorithms serving fo...

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IEEE Energy Conversion Congress and Exposition, ECCE

作者： Sideng Hu Zhengming Zhao Liqiang Yuan Ting Lu Xuesong Wang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

The discrete control technology for AC machine drives is widely applied in the industrial field. This paper aims to excavate new approaches to enhance the discrete control system in AC motor drive systems from following aspects: matching design for discrete subsystems, synchronization in the signal processing and dealing with the restrictions in the voltage output. The proposed approaches are incorporated with three key techniques applied in high performance induction motor drive systems: DC pre-excitation, parameter identification and flux observer with a sensorless control to verify the feasibility. The anti-interference and synchronization procedure in the implementation are also proposed. The experimental results from the test on 55kW/400V and 160kW/400V ASD (Adjustable Speed Drives) systems validate the effectiveness of the proposed approaches.

关键词： Switches Variable speed drives Observers Parameter estimation Pulse width modulation Induction motors

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