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International Conference on Renewable power generation (RPG 2015)

作者： Hongping Li Fei Wang Hui Ren Hongbin Sun Chun Liu Bo Wang Jing Lu Zhao Zhen Xiaoli Liu State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources (North China Electric Power University) Baoding 071003 Hebei Province China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment (Department of Electrical Engineering Tsinghua University) Haidian District Beijing 100084 China China ElectricPowerResearch Institute HaidianDistrict Beijing 100192 China

Irradiance changes caused by clouds movement are the main factors, which lead to mutation of photovoltaic power. In order to increase the accuracy of the ultra-short-term photovoltaic power prediction, based on of clouds images, the cloud identification for sky images is one of the primary aspects for improving photovoltaic power accuracy. A cloud identification model for sky images is established based on Otsu. Firstly, a series of sky images are collected by Total Sky Imager (TSI) with the regions of clouds and sky are distinguished. Secondly, the color features (based on RGB values) of pixels in sample images and the spectral and texture features of the whole image are extracted; Finally, we established a cloud identification model for sky images based on Otsu according to the clouds' and sky areas' division and the general characteristics featured by pixels and images. The simulated results show that the model in this paper can identify the clouds in a sky images effectively.

关键词： Otsu cloud identification texture threshold Clouds sky images texture textures pixel

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Analysis and suppression of subsynchronous oscillation of Rudong wind power through MMC-HVDC system

Analysis and suppression of subsynchronous oscillation of Ru...

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2021 Annual Meeting of CSEE Study Committee of HVDC and power Electronics (HVDC 2021)

作者： J. Li X. Xie J. Yang H. Li Z. Shi K. Wang C. Fu W. Yang Key Laboratory of Far-shore Wind Power Technology of Zhejiang Province Huadong Engineering Corporation Limited Power China Hangzhou Zhejiang Province 310014 China State Key lab of Control and Simulation of Power Systems and Generation Equipment (Dept. of Electrical Engineering Tsinghua University) Haidian District Beijing 100084 China

There may be complex interaction between the converter control systems of wind power and MMC-HVDC, which will lead to sub-/super-synchronous oscillation and threaten the safe and stable operation of the system. The relevant events have been reported in Guangdong Nan'ao, Shanghai Nanhui and Zhangbei projects. Rudong offshore wind power project is the first offshore wind power transmission system in China, and it is still under construction. Therefore, it is of great significance to carry out the research on the risk analysis and suppression measures of sub-synchronous oscillation in Rudong wind power MMC-HVDC system. First, the time-domain simulation model of Rudong wind power MMC-HVDC system is built in the PSCAD/EMTDC simulation model. Then, the effects of the number of wind turbine generators, wind power output and the parameters of MMC-HVDC controller on the sub-/super-synchronous oscillation characteristics of the system are further analyzed. Finally, the suppression measures based on supplementary frequency dependent gain control are proposed, the application position of the controller is discussed, and the parameter optimization method of the controller is given. The research content provides a certain guiding significance for the operation and control of Rudong wind power MMC-HVDC.

关键词： turbogenerators HVDC power transmission wind turbines power transmission control risk analysis time-domain analysis offshore installations HVDC power convertors wind power plants wind power

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An Iterative-Correction Approach of Risk-Constrained Unit Commitment of power systems with Wind power based on Optimal Reserve Decision

An Iterative-Correction Approach of Risk-Constrained Unit Co...

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power, Energy and Electrical Engineering (CPEEE), International Conference on

作者： Ying Qiao Yisha Lin Haibo Li Xuebin Wang State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China Sichuan Energy Internet Research Institute of Tsinghua University Chengdu China State Grid Qinghai Electric Power Co. Ltd Xining China

ISBN: (数字)9781728177175

ISBN: (纸本)9781728177182

The operation risk may increase with the high penetration of wind power, but the calculation of risk indices is complex and nonlinear, which makes it difficult to incorporate the risk constraints into the conventional unit commitment (UC) model. This paper focuses on accurately handling the risk constraints instead of approximate exponential decay rules, and proposes an iteration-correction methodology to solve risked-constrained UC of power systems with wind power. The proposed method calculates the risk indices based on the PJM method, and modifies the minimum reserve demand in each iterative step if the risk indices exceed the limits. A dynamic iterative speed-up equation is given to decrease the elapsed time. The case studies based on the actual system of China are conducted to validate the effectiveness. Compared with the conventional reserve limit, the precise and optimal reserve decision is made under different risk levels, and the proposed UC has merits of less cost and lower risk.

关键词： Uncertainty power system dynamics Wind power generation power grids Mathematical model Iterative methods Optimization

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Research of protection communication system in process level of intelligent substation

Research of protection communication system in process level...

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International Conference on Advanced power System Automation and Protection (APAP)

作者： Fei Xu Bin Wang Xinzhou Dong Runbin Cao Kun Liu Yuelin Yang Tingting Wu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China College of information and electrical engineering China Agricultural University college of information and electrical engineering China Agricultural University School of Electrical Engineering & Renewable Energy China Three Gorges University Yichang China

The paper mainly focuses on the communication problem based on IEC61850 communication protocol. As in the process level communication system: MU (Merging Unit)-Switch-DIPC (Digital Integrated Protection and control system), the stability of SMV packets transmission is very important. The transmission delay of the process level communication is the key problem that may restrict the protection algorithm and capability. In the meantime, GPS synchronization problem of MUs, protection capability of the integrated protection device and stability of SMV message transmission based on the existing DIPC(DIP-01) system will also be discussed in the paper. Through the experiment and analysis, the paper gives out the key factors that lead to the message transmission delay and packets loss. The work at last gives out some primary ideas to improve the protection capability.

关键词： Random access memory Switches Synchronization Optical fiber devices Delay

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Designation and development of hardware platform for intelligent ter-minal in 126kV Smart substation

Designation and development of hardware platform for intelli...

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International Conference on Advanced power System Automation and Protection (APAP)

作者： Tong Sun Bin Wang XinZhou Dong ShuJian Zhang MingCai Kang RunBin Cao School of Automation Nanjing University of Science and Technology Jiangsu 210094 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Electrical engineering and automation Hefei University of Technology Anhui 230009 China

According to the demand of 126kV intelligent switch with intelligent operative box, an intelligent terminal device by using cooperation control of embedded CPU (STM32F103ZET6 ARM) and Field Programmable Gates (Cyclone II EP2C8Q208C8 FPGA), which is up to the IEC61850 standard, is designed in this paper. Research program of the device is discussed. Starting from the modularization structure design, function of each module, circuit design and implementation method were introduced in detail. A hardware platform was established according to the design. Finally, the article confirmed the correctness of the hardware platform primarily through experimental method.

关键词： Optical fiber LAN Voltage measurement Measurement units Optical fibers Switchgear Field programmable gate arrays Sun

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Dynamic frequency support by photovoltaic generation with 'synthetic' inertia and frequency droop control

Dynamic frequency support by photovoltaic generation with 's...

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2017 IEEE Conference on Energy Internet and Energy System Integration, EI2 2017

作者： Jietan, Zhang Linan, Qu Pestana, Rui Fengkui, Luan Libin, Yang State Grid QingHai Electric Power Research Institute China QingHai Province Key Laboratory of Photovoltaic Grid Connected Power Generation Technology China China Electric Power Research Institute China State Key Laboratory of Operation and Control of Renewable Energy and Storage Systems China Electric Power Research China R and D Nester Centro de Investigação em Energia REN - State Grid S.A. Rua Cidade de Goa 4-B Sacavém Portugal REN - Rede Eléctrica Nacional S.A. Rua Cidade de Goa 4-B Sacavém Portugal State Grid Corporation of China China

ISBN: (纸本)9781538614273

Recently solar photovoltaic (PV) power generation increases rapidly all over the world. Because of variability, uncertainty, stability and reliability of power system with high penetration of PV generation faces challenges. Frequency stability is one most important thing for power system. In this paper, "synthetic" inertia control and frequency droop control for PV power generation is proposed, with de-loaded operation. "synthetic" inertia control is used to prevent frequency change rate once disturbance occurs, and differential of frequency signal is leaded into control structure of PV inverter. Frequency droop control is used to re-establish frequency after disturbance, using deviation between frequency and its reference. PV power generation, with control method demonstrated as above, is performed in software DIgSILENT powerFactory, to evaluate the dynamic frequency support capability of PV power generation to power system. The simulation results are demonstrated that PV generation is capable to support dynamic frequency. © 2017 IEEE.

关键词： power control

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Low-Frequency Offshore Wind power Transmission System with Dual-End Grid-Forming control

Low-Frequency Offshore Wind Power Transmission System with D...

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International Conference on Renewable Energy and power Engineering (REPE)

作者： Nan Fu Bao Liu Yunfei Xu Sitong Zhu Kui Wang Yongdong Li State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China State Key Laboratory of Advanced Power Transmission Technology State Grid Smart Grid Research Institute Co. Ltd Beijing China Electric Power Research Institute of State Grid Liaoning Electric Power Co. Ltd. Shenyang China

ISBN: (数字)9798350375558

ISBN: (纸本)9798350375565

The offshore wind power has been gaining increasing attention in recent years. Low-frequency alternating current (LFAC) transmission is emerging as a promising technology with specific advantages for offshore wind power transmission. This paper discusses the structure and control of the offshore wind power transmission system based on LFAC. In order to enhance the support for the power system, grid-forming control can be implemented on both sides of the modular multilevel matrix converter (M3C) used in LFAC. Additionally, the capacitor voltage control of M3C is briefly introduced. Furthermore, power reserve control is utilized to enable wind turbines to participate in primary frequency regulation. Finally, the effectiveness of the designed control system is verified through simulation using PSCAD/EMTDC, further demonstrating the efficacy of the strategy.

关键词： Current control Capacitors Wind power generation Wind farms control systems Wind turbines Voltage control Matrix converters Frequency control Grid forming

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Improving Surface Performance of Composite Insulators by Multifunctional Nano-Coating

SSRN

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SSRN 2022年

作者： Liu, Shuming Liu, Shuqi Wang, Qian Zuo, Zhou Liang, Xidong Chen, Zhong State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China School of Material Science and Engineering Nanyang Technological University 639798 Singapore

Insulator is an important component of outdoor insulation systems. It works in complex environments and faces a series of problems such as surface contamination, loss of hydrophobicity, accumulation of surface charges, which may eventually lead to flashover. Aiming to solve these problems in a simple and scalable method, we propose a multifunctional nano-coating based on SiO 2 /PDMS/EP. By the combination of multiscale structure and low surface energy modification, this coating shows excellent water-repellency performance, a large contact angle greater than 160° and a small rolling angle near 0° are achieved on coated silicone rubber, which enables the surface with excellent self-cleaning performance. Benefiting from the multiscale roughness, the heat transfer is inhibited by the reduced contact area, which further slows down the icing process on coated silicone rubber. The de-icing force on coated silicone rubber is also smaller than that on pristine silicone rubber. This coating also introduces many shallow traps to the surface, which is beneficial to the fast surface charge dissipation in a short time. Besides, the high water-repelling ability can promote the droplet to roll away under the action of electrical field force, which alleviates the electrical distortion caused by the droplets. As a result, the wet flashover voltage of coated silicone rubber is 60% higher than that of pristine silicone rubber. This multifunctional coating is a facile, scalable, and effective approach to improving the comprehensive surface performance of insulators. © 2022, The Authors. All rights reserved.

关键词： Flashover

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Achieving an accurate random process model for PV power using cheap data: Leveraging the SDE and public weather reports

arXiv

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arXiv 2021年

作者： Qiu, Yiwei Lin, Jin Zhou, Zhipeng Dai, Ningyi Liu, Feng Song, Yonghua College of Electrical Engineering Sichuan University Chengdu610065 China State Key Laboratory of the Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing100087 China State Key Laboratory of Internet of Things for Smart City University of Macau 999078 China Department of Electrical Engineering Tsinghua University Beijing100087 China

The stochastic differential equation (SDE)-based random process models of volatile renewable energy sources (RESs) jointly capture the evolving probability distribution and temporal correlation in continuous time. It has enabled recent studies to remarkably improve the performance of power system dynamic uncertainty quantification and optimization. However, considering the non-homogeneous random process nature of PV, there still remains a challenging question: how can a realistic and accurate SDE model for PV power be obtained that reflects its weather-dependent uncertainty in online operation, especially when high-resolution numerical weather prediction (NWP) is unavailable for many distributed plants? To fill this gap, this article finds that an accurate SDE model for PV power can be constructed by only using the cheap data from low-resolution public weather reports. Specifically, an hourly parameterized Jacobi diffusion process is constructed to recreate the temporal patterns of PV volatility during a day. Its parameters are mapped from the public weather report using an ensemble of extreme learning machines (ELMs) to reflect the varying weather conditions. The SDE model jointly captures intraday and intrahour volatility. Statistical examination based on real-world data collected in Macau shows the proposed approach outperforms a selection of state-of-the-art deep learning-based time-series forecast methods. Copyright © 2021, The Authors. All rights reserved.

关键词： Random processes

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Robust mean-variance optimization for self-scheduling of thermal producer and its price of robustness

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2015年第2期35卷 319-326页

作者： Ding, Tao Bo, Rui Sun, Hongbin Huang, Can Li, Fangxing State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China Midwest ISO Street Paul MN55108 United States Department of Electrical Engineering and Computer Science University of Tennessee Knoxville TN37996 United States

In deregulated electricity markets, generation companies with the aim of maximum revenue need to provide trading strategies to the electricity trading market, which contributed to a self-scheduling model. When considering the uncertainty of price, the trading strategies are required to maximize the revenue as well as minimizing the risks brought by uncertainties. In this paper, a multi-objective robust mean-variance model was proposed to solve the above problem and the Pareto frontier of the multi-objective optimization was obtained. Moreover, the proposed robust mean-variance model could be equivalently transformed into a non-robust mean-variance model which was casted as a second-order cone programming (SOCP) optimization. The price of robustness to benefits, risks, and the Pareto frontier were analyzed. Finally, the robust mean-variance model based self-scheduling model optimization and its budget of robustness were tested on a 30-bus system. The simulation results demonstrate the effectiveness of the proposed method and analysis. © 2015 Chin. Soc. for Elec. Eng.

关键词： Second-order cone programming

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