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ICEMS 2005: 8th International Conference on Electrical Machines nd systems

作者： Wang, H.Y. Su, P.S. Wang, X.H. Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing 10084 China

ISBN: (纸本)7506274078

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 surf ace-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： Electric transformers

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A Joint Prediction Method of Multi-state Variables for High-Voltage Cables Based on GRU 10th

A Joint Prediction Method of Multi-State Variables for High-...

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10th Frontier Academic Forum of Electrical Engineering, FAFEE 2022

作者： Chen, Jianning Zhou, Yuanxiang Lin, Menglong Pan, Zehua Ge, Jiamin State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9789819934034

In order to carry out risk warning for high-voltage cable transmission system and realize differentiated operation and maintenance decision-making, it is necessary to carry out time series prediction for online monitoring state quantities of high-voltage cables such as load current, partial discharge, and grounding circulating current. Therefore, a joint prediction method for multi-state variables of high-voltage cables based on Gate Recurrent Unit (GRU) is proposed. Taking the online monitoring state quantities of a certain area in central China in May as the analysis data set, a GRU network is built to predict the sequence of multi-state quantities, compared with different models. Taking the phase A load current of a node of the cable as an example to carry out state prediction, the results show that compared with the Long Short Term Memory (LSTM) neural network, back-propagation neural network (BPNN), and Auto Regressive Integrated Moving Average (ARIMA) model, the accuracy of the sequence prediction model based on GRU is Higher. When predicting for 5 min, the MAE and RMSE are 1.94 and 2.65 A, respectively, with the MAPE of 0.54%. When predicting for 30 min, the MAE and RMSE are 9.81 and 15.36 A, respectively, with the MAPE of 2.89%. When predicting for 1 h, the MAE and RMSE are 17.05 and 27.47 A, respectively, with the MAPE of 4.91%. The GRU model performs better due to the suppression on over-fitting of training data with simpler model structure. © Beijing Paike Culture Commu. Co., Ltd. 2023.

关键词： Forecasting

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A combined time-and-frequency-domain model for integration of wind power generation

A combined time-and-frequency-domain model for integration o...

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2016 IEEE Innovative Smart Grid Technologies - Asia, ISGT-Asia 2016

作者： Chen, Xiaoshuang Lin, Jin Wan, Can Song, Yonghua Guo, Wanfang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9781509043033

Wind power generations (WPGs) are different from traditional generations for their considerable fluctuations. It is challenging to describe the status of a system with power fluctuation injections, especially when considering complicated network constraints. This paper proposes a combined time-and-frequency-domain (CTFD) model to evaluate whether the constraints will be violated under fluctuating wind power injection. The constraints of energy units and branch power flow are described in a generalized form, and are related to the power spectral density of power fluctuations. The distributions of the constraint variables are then discussed based on the CTFD model, and a chance criterion is conducted to describe the probability of the constraints being violated. Case studies show the effectiveness of the proposed model. © 2016 IEEE.

关键词： Probability distributions

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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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ICEMS 2005: 8th International Conference on Electrical Machines nd systems

作者： Sun, Yuguang Wang, Xiangheng Gui, Lin Wang, Weijian Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing 100084 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： Electric generators

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Flexible unbalanced control with peak current limitation for virtual synchronous generator under voltage sags

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Journal of Modern power systems and Clean Energy 2018年第1期6卷 61-72页

作者： Tianwen ZHENG Laijun CHEN Yan GUO Shengwei MEI State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Qinghai Key Lab of Efficient Utilization of Clean Energy New Energy Photovoltaic Industry Research Center Qinghai University

Virtual synchronous generator(VSG)is gridfriendly for integrating distributed generations(DGs)since it can emulate the operation mechanism of traditional synchronous generator(SG).However,the traditional VSG control strategy,which is mainly suitable for balanced voltage conditions,may lead to power oscillations,current unbalance and even overcurrent under unbalanced voltage *** overcome this difficulty,a flexible unbalanced control with peak current limitation for VSG under unbalanced operating conditions is *** on the basic VSG control algorithm,the control strategy integrates two novel control modules,which are current reference generator(CRG)and power reference generator(PRG).The proposed control strategy can flexibly meet different operation demands,which includes current balancing,constant active or reactive *** the injected currents are kept within safety values for a better utilization of the VSG power ***,the experimental platform is *** results demonstrate the validness and effectiveness of the proposed control strategy.

关键词： Virtual synchronous generator Unbalanced control Current reference generator power reference generator Voltage sags

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Capacity Optimization of Hydrogen Buffer Tanks in Renewable power to Ammonia (P2A) System

Capacity Optimization of Hydrogen Buffer Tanks in Renewable ...

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2020 IEEE power and Energy Society General Meeting, PESGM 2020

作者： Li, Jiarong Lin, Jin Song, Yonghua Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing China Department of Electrical Engineering Department of Electrical and Computer Engineering Beijing China

ISBN: (纸本)9781728155081

power to hydrogen is a promising method to consume surplus renewable energy existing in the world. However, due to bottlenecks in hydrogen storage and transportation, converting hydrogen into ammonia which is a kind of hydrogen carrier with satisfied quality in storage and transportation is considered. Industrial ammonia synthesis reactors always work in constant conditions with constant flow rate of the feed gas, while hydrogen output of electrolyzers may vary sharply across renewable energy, thus hydrogen buffer tanks are required between electrolyzers and reactors to eliminate the fluctuation to some extent. The capacity of the buffer needs to be optimized due to relatively expensive cost of tanks, and the optimal capacity of the buffer actually depends on the operation flexibility of the reactor which is rarely discussed in existing literatures. This paper studies operation flexibility of the reactor first and establishes operation model of ammonia synthesis system under variable working conditions, on this basis the capacity optimization model is proposed and verified by a P2A system. At last the operation performance and the economy of P2A system are discussed, and case studies show that about 24% of total investment cost can be reduced with the consideration of operation flexibility of the reactor. © 2020 IEEE.

关键词： Ammonia

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Movement simulation of long electric arc along the surface of insulator string in free air

Movement simulation of long electric arc along the surface o...

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作者： Gu, Shanqiang He, Jinliang Zhang, Bo Xu, Guozheng Han, Shejiao State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

This paper presents the study of a long electric arc in free air due to lightning stroke on the parallel gap lightning protection device (PGLPD) on high-voltage overhead transmission lines. Based on the latest electric arc model, the analysis method of the magnetic field generated by the current flowing through the PGLPD, electric arc, transmission lines, steel tower, and ground wires is developed, and the movement process of the long arc along the surface of the insulator strings is simulated. The simulation results are in agreement with the experimental results. The study is very helpful for the optimal design and suitable assemblage of the PGLPD. © 2006 IEEE.

关键词： Electric arcs

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Steady-state model of multi-port electric energy router and power flow analysis method of AC/DC hybrid system considering control strategies

Steady-state model of multi-port electric energy router and ...

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作者： Shen, Yu Zhu, Fengju Zhang, Chunpeng Cai, Weiqian Yuan, Liqiang Li, Kai Zhao, Zhengming State Key Lab of Control and Simulation Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

This study proposes a steady-state model of multi-port electric energy router (EER) and a power flow analysis method for AC/DC hybrid system considering control strategies. Firstly, a circuit topology model of EER is put forward, including AC and DC port equivalent parts. Secondly, considering external control characteristics of EER, the control strategies including PQ mode, V/f mode, and droop mode are established, which is suitable for system analysis. Then, using the extended sub-network model, an AC/DC power flow model containing multi-port EER is established. In terms of the power flow algorithm for AC/DC hybrid system, AC/DC network admittance matrix and the extended AC/DC network modification equations are applied to solve the problem. Two examples are designed and show that EER can be used for flexible power regulation and voltage improvement. Besides, power flow analysis method of AC/DC hybrid system is demonstrated to be effective. © 2019 Institution of Engineering and *** right reserved.

关键词： Topology

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Comprehensive power-supply planning for active distribution system considering cooling,heating and power load balance

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Journal of Modern power systems and Clean Energy 2015年第4期3卷 485-493页

作者： Xinwei SHEN Yingduo HAN Shouzhen ZHU Jinghong ZHENG Qingsheng LI Jing NONG State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Grid Planning&Research Center Guizhou Power Grid CooporationCSGGuiyang 550002China

An active distribution system power-supply planning model considering cooling,heating and power load balance is proposed in this paper.A regional energy service company is assumed to be in charge of the investment and operation for the system in the *** expansion of substations,building up distributed combined cooling,heating and power(CCHP),gas heating boiler(GHB)and air conditioner(AC)are included as investment planning *** terms of operation,the load scenarios are divided into heating,cooling and transition ***,the extreme load scene is included to assure the power supply reliability of the *** results demonstrate the effectiveness of the proposed model and illustrate the economic benefits of applying distributed CCHP in regional power supply on investment and operation.

关键词： Active distribution system Combined cooling heating and power(CCHP) power-supply planning Load balance

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Analysis of Adaptive Re-closure in AC-DC Hybrid power System 8

Analysis of Adaptive Re-closure in AC-DC Hybrid Power System

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8th IEEE International Conference on Advanced power System Automation and Protection, APAP 2019

作者： Xie, Min Zhang, Wei Liu, Ludeng Jia, Xin Wang, Bin Dong, Xinzhou Dispatching and Controlling Center of Anhui Electric Power Company State Grid Hefei China Tsinghua University Key Lab of Control and Simulation of Power Systems and Generation Equipment China

ISBN: (纸本)9781728117225

The beat frequency characteristic of the recovery voltage of fault phase in the case of single-phase grounding transient fault happening to line with the shunt reactors is analyzed. Besides, the paper analyzes the reason of no beat frequency phenomenon of transient fault happening to line without shunt reactor. The AC power networks with metallic grounding fault and arc grounding fault are analyzed by simulation. The recovery voltage of single-phase grounding fault in AC/DC hybrid power grid is studied by PSCAD. The new problems of the adaptive re-closure in AC-DC hybrid power system are discussed. Then the follow-up ideas to solve several existing problems are also presented. © 2019 IEEE.

关键词： Electric power transmission networks

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