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Reform Practice of Electrical Engineering Undergraduate Teaching System for Energy Internet
ZHU Guiping, LIN Jin, SUN Hongbin, KANG Chongqing, YU Xinjie, ZENG Rong
Proceeding of the CSEE    2020, 40 (13): 4063-4071.   DOI: 10.13334/j.0258-8013.pcsee.200461
Abstract1795)      PDF(pc) (950KB)(208)       Save
Building the energy internet has become a national energy strategic with rapid industrial development in China to achieve the deep integration of the energy system and the information internet. In order to meet the national strategic demand and lead the industrial development, universities must play the role of cultivating the inter-disciplinary talents needed for the energy internet. Since energy internet is a typical multi-disciplinary field, this paper systematically introduced the reform process and practical experience of the talent training program in the direction of energy internet based on the electrical engineering training program in the Department of Electrical Engineering of Tsinghua University in the past 5 years. The paper presented the knowledge structure required by energy internet professionals, and the advantages of establishing the energy internet undergraduate teaching system based on current electrical engineering program. The paper also took the energy internet undergraduate training program of the Department of Electrical Engineering of Tsinghua University as an example, and introduced the education concept cooperated with R&D and specific measures adopted in the process of talent training in the direction of energy internet. It is hoped to provide a valuable reference for the training of talents in the direction of the energy internet in China.
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Analysis on Blackout in Great Britain Power Grid on August 9th, 2019 and Its Enlightenment to Power Grid in China
SUN Huadong, XU Tao, GUO Qiang, LI Yalou, LIN Weifang, YI Jun, LI Wenfeng
Proceeding of the CSEE    2019, 39 (21): 6183-6191.   DOI: 10.13334/j.0258-8013.pcsee.191632
Abstract655)      PDF(pc) (1401KB)(589)       Save
On August 9, 2019, Great Britain power grid suffered a massive blackout. The accident caused service disruption in some major British cities, including London, and affected about 1 million people. This paper introduced the general situation of Great Britain power grid prior to the accident, the detailed process and the cause of the accident. Then, the development process of each stage of the accident was sorted out and the cause of the accident was summarized according to the official investigation report of this accident. Finally, combined with the actual situation of China’s power grid, this paper summarized the enlightenment of this accident. Finally, with the consideration China power grids, this paper proposed some suggestions for preventing such accidents.
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Recent Progress on Characteristics and Applications of Atmospheric Pressure Low Temperature Plasmas
MEI Danhua, FANG Zhi, SHAO Tao
Proceeding of the CSEE    2020, 40 (4): 1339-1358.   DOI: 10.13334/j.0258-8013.pcsee.191615
Abstract385)      PDF(pc) (5454KB)(268)       Save
Recent progress on the atmospheric pressure low temperature plasmas is summarized and analyzed from the viewpoints of basic characteristics and practical applications based on the related research progress and the academic reports presented in the 2018 National Conference on High Voltage and Discharge Plasmas (HVDP2018). The theoretical-study related to basic characteristics are focused on the plasma power sources, plasma generation devices, experimental diagnostics and simulation methods, while the practical applications are mainly concentrated on the areas of material processing, energy conversion, environmental protection, biomedicine, aerospace, agriculture and food. It can be seen that gratifying achievements have been made in the basic characteristics and applications of atmospheric pressure low temperature plasmas in China in recent years. In the future, we should focus on the basic theoretical and key technical problems that restrict the rapid development of some specific applications and develop practical application-oriented plasma theory and process systems, with the aim of promoting the extensive applications of atmospheric pressure low temperature plasma technology.
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Energy Circuit Theory of Integrated Energy System Analysis (I): Gaseous Circuit
CHEN Binbin, SUN Hongbin, CHEN Yuwei, GUO Qinglai, WU Wenchuan, QIAO Zheng
Proceeding of the CSEE    2020, 40 (2): 436-443.   DOI: 10.13334/j.0258-8013.pcsee.200028
Abstract270)      PDF(pc) (494KB)(381)       Save
The integrated energy system has been a hotspot and frontier of international research. To realize the disciplinary integration of different energy network research, an energy circuit theory was proposed based on the methodology of the deduction from “field” to “circuit” in the electric circuit theory. This paper derived a gaseous circuit model with distributed parameters in the time domain from the conservation equations of mass and momentum. Fourier transform was employed to map the gaseous circuit into the frequency domain and a two-port equivalent model with lump parameters was proposed to simplify the gaseous circuit model from partial differential equations to algebraic equations. Finally, the network matrix and network equation of the natural gas network were derived based on the gaseous circuit, having a unified mathematical form with those of the electricity network. It establishes the theoretical basis for the integrated analysis of the heterogeneous energy flows. The gaseous circuit method has less computational complexity and outperforms the conventional analysis method in terms of efficiency under the same accuracy.
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An Overview on Research Progress of Coreless Stator Axial Flux Permanent Magnet Synchronous Motor
LIU Xiangdong, MA Tongkai, ZHAO Jing
Proceeding of the CSEE    2020, 40 (1): 257-273.   DOI: 10.13334/j.0258-8013.pcsee.190991
Abstract232)      PDF(pc) (2345KB)(240)       Save
The coreless stator axial flux permanent magnet synchronous motor (AFPMSM) has received more and more attention due to its compact structure, high power density and torque density, no core loss and high efficiency. In the occasions requiring space compactness and high torque density, it has broad application prospects. This paper introduced the typical topology of the coreless stator AFPMSM, analyzed the design and analysis method and a series of optimization methods for the electromagnetic performance of such motors, discussed the thermal performance analysis optimization and mechanical performance analysis of such motors, and summarized the control strategy proposed by the characteristics of such motor winding inductance is small and the research on the weak magnetic expansion speed. Finally, the application and future development direction of the coreless stator AFPMSM research field was prospected.
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Blockchain-enabled Charging Right Trading Among EV Charging Stations: Mechanism,Model,and Method
WANG Haoran, CHEN Sijie, YAN Zheng, PING Jian
Proceeding of the CSEE    2020, 40 (2): 425-435.   DOI: 10.13334/j.0258-8013.pcsee.182244
Abstract217)      PDF(pc) (455KB)(249)       Save
Increasing penetration of electric vehicles (EVs) give rise to the challenges in the secure operation of power systems. The EV charging loads should be distributed among charging stations in a fair and incentive-compatible manner while ensuring that power transmission and transformation facilities are not overloaded. This paper proposed a blockchain-based charging right (or charging power ration) trading mechanism and model. A charging station needs to submit the charging demand for a future period. The blockchain first distributed initial charging rights in a just manner and ensures the security of facilities. Given that the charging urgency and elasticity differences vary by charging stations, all charging stations then proceeds double auction and peer-to-peer (P2P) transaction of charging rights. Bids and offers were cleared via double auctions if bids were higher than offers. The remaining bids and offers were cleared via the P2P market. Then, the paper designed a charging right distribution and trading platform and smart contract based on the Ethereum blockchain to ensure the safety of the distribution network and the transparency and efficiency of charging right trading. Simulation results based on Ethereum private blockchain show the fairness and efficiency of the proposed mechanism and the effectiveness of the method.
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Design and Key Technology Development of Permanent Magnet Assisted Synchronous Reluctance Motor
XU Meimei, LIU Guohai, CHEN Qian, ZHAO Wenxiang
Proceeding of the CSEE    2019, 39 (23): 7033-7043.   DOI: 10.13334/j.0258-8013.pcsee.182323
Abstract193)      PDF(pc) (2506KB)(291)       Save
The permanent magnet assisted synchronous reluctance motor (PMaSynRM) combines the advantages of permanent magnet synchronous motor and synchronous reluctance motor, such as high torque/power density, wide speed range and high-cost performance. It has broad application prospects in the fields of electric vehicles, medical equipments, and aerospaces. This paper firstly introduced the working principle of PMaSynRM and discussed the research work of PMaSynRM at home and abroad. Then, researches about the PMaSynRM were summarized through the following aspects: the mechanical stress, the torque ripple suppression, and high fault tolerance performance design. Finally, the developing trends of PMaSynRM were analyzed based on the development status of PMaSynRM.
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Multiple Time-scale Optimal Scheduling of Community Integrated Energy System Based on Model Predictive Control
WANG Chengshan, LÜ Chaoxian, LI Peng, LI Shuquan, ZHAO Kunpeng
Proceeding of the CSEE    2019, 39 (23): 6791-6803.   DOI: 10.13334/j.0258-8013.pcsee.181058
Abstract180)      PDF(pc) (654KB)(347)       Save
In combined cooling, heating and power systems, multiple energy devices must be coordinated to optimize operations and meet energy demands economically and reliably. A reasonable and effective scheduling strategy is the key to achieving this goal. The optimal scheduling of a real community integrated energy system in winter was studied. On the basis of building detailed models of the devices, a model predictive control based two-stage scheduling strategy of multiple time-scale was developed. In the rolling optimization stage, multiple devices ware coordinated to minimize the operation cost and unit startup/shutdown penalty under the time of use tariff mechanism and the schedule of large time-scale was formulated by multi-step’s rolling optimization. In the dynamic adjustment stage, the operation conditions of the devices ware adjusted based on the schedule of the rolling stage to deal with the small time-scale uncertainties of renewable energy and the loads. The analysis results show that the scheduling method in the paper can decrease the operation cost and startup times of the units by coordinating the operation of energy supply and thermal storage devices and utilizing these benefits of complementary operation of them. The introduction of the dynamic adjustment stage can response to the small time-scale changes of renewable energy and the loads quickly and meet the energy demands reliably and economically.
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Mechanism Analysis and Suppression Method of Wideband Oscillation of PMSG Wind Farms Connected to Weak Grid (Part II): Suppression Method of Wideband Oscillation Based on Impedance Reshaping
LI Guanghui, WANG Weisheng, LIU Chun, JIN Yiding, NIAN Heng, HE Guoqing
Proceeding of the CSEE    2019, 39 (23): 6908-6920.   DOI: 10.13334/j.0258-8013.pcsee.191071
Abstract179)      PDF(pc) (1663KB)(192)       Save
The first of this series papers has studied the wideband oscillation phenomenon in permanent magnet synchronous generators (PMSG) wind farms connected to AC weak grid, and analyzed the mechanism. The impedance reshaping method based on the control parameters optimization and strategy improvement design has become a useful method of oscillation suppression. The previous literature usually designs the impedance reshaping for the specific oscillation frequency band after the occurrence of the oscillation accident, the wideband reshaping design method suitable for complex grid environment is lacked. An impedance reshaping control strategy involving active damping and virtual admittance was proposed for the oscillation problems in frequency band III and IV. The analytical impedance model considering the impedance reshaping control was established and verified. Considering the band overlap effect between different frequency bands analyzed in first paper of the series, the unified iterative optimization design of the control parameters of each controller was carried out, and the impedance reshaped of the frequency band II, IV and III were realized successively, improving the system stability margin of PMSG connected to AC weak grid. Finally, based on the control hardware-in-the-loop (CHIL) simulation platform, the impedance reshaping and wideband oscillation mitigation for a practical PMSG were carried out, and the effectiveness of the proposed strategy was verified.
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Integrated Energy Service Based on Blockchain Technology
GONG Gangjun, WANG Huijuan, YANG Sheng, SUN Yue, SU Chang, WEN Yafeng, YANG Haixia
Proceeding of the CSEE    2020, 40 (5): 1397-1408.   DOI: 10.13334/j.0258-8013.pcsee.190062
Abstract171)      PDF(pc) (639KB)(278)       Save
To seek the new developing mode is the direct power to promote the transformation of power grid companies from electric energy suppliers to integrated energy service providers. Therefore, it is necessary to study the value-added service types, differentiated demands, negotiation mechanisms, transaction modes and operation management and control systems in the whole process of “source-network-sale-load” in the market environment. In this paper, it analyzed the application of blockchain and integrated energy service. A integrated energy service network architecture based on blockchain technology was built around the two tasks of integrated energy and integrated services. At the same time, a integrated energy service network architecture based on blockchain technology was built. A chain transaction model based on multi-chain integrated energy service was designed. Different transaction patterns and information interaction processes between nodes were analyzed, then the proof of sharing-stake (PoSS) consensus mechanism was proposed based on proof of stake (PoS). It used a combination of consensus to achieve the realization of service consensus among different subjects. Finally, the feasibility of a single master-slave chain was verified by the construction of the multichain platform. It provides a reference for proving the applicability of blockchain in the integrated energy service scenarios and the application of blockchain technology in integrated energy services.
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Temporal and Spatial Characteristics of Power System Inertia and Its Analysis Method
ZENG Fanhong, ZHANG Junbo
Proceeding of the CSEE    2020, 40 (1): 50-58.   DOI: 10.13334/j.0258-8013.pcsee.190084
Abstract169)      PDF(pc) (1079KB)(281)       Save
With the increasing of wind power and photovoltaic penetrations, the power system inertia has changed in characteristics and forms. Traditional power system inertia researches mainly focused on the system or regional level analysis and few mentioned the inertia of each system node, therefore, it is difficult to analysis the temporal and spatial characteristics of power system inertia and more valuable details are hardly provided for the system safety and stability analysis. To cope with this problem, the physical attributes of inertia in power systems, and then proposed the concept of node inertia and its physical interpretation/ representation were illustrated. After that, based on the dynamic characteristics of node frequencies under large and small disturbances, methods for the temporal and spatial characteristics of power system inertia analysis were proposed, followed by a visualization method which provides real-time monitoring of power system inertia distribution. Simulations were carried out in the 10-machine 39-bus system, and results validate the proposed method.
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Research on Online Optimal Dispatching of Residential Energy Consumption Based on Multi-agent Asynchronous Deep Reinforcement Learning
ZHANG Hong, SHEN Xin, MU Haoyuan, LIU Aidong, WANG He
Proceeding of the CSEE    2020, 40 (1): 117-127.   DOI: 10.13334/j.0258-8013.pcsee.182498
Abstract165)      PDF(pc) (782KB)(243)       Save
To promote the flexible load participating in demand response efficiently, this paper applied asynchronous deep reinforcement learning (ADRL) to optimize the online scheduling of household energy management system, helping customers transition from a passive to an active role and achieving the maximum benefit. According to the characteristics of electrical equipment, the paper described the state of appliances from the perspective of probability theory in the smart grid context. The asynchronous advantage actor-critic (A3C) method was proposed to simultaneously perform multi-action decisions with the probability distribution of historical operating state via multi-agent using the CPU multi-threading function. The proposed method was validated on a large-scale database, which includes information about photovoltaic power generation, electric vehicles as well as residential appliances. Finally, the comparative analysis of decision-making effects show that online energy consumption scheduling strategies can achieve economic goals by providing real-time feedback to consumers.
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Guohua Yongfa Wind Farm Wind Turbine Control Strategy Optimization and Frequency Converter Upgrade Application
YU Jianguo, BIAN Hui, LI Qiang, ZHANG Cunjia, GAO Yingjun
Proceeding of the CSEE    2019, 39 (23): 6964-6970.   DOI: 10.13334/j.0258-8013.pcsee.190369
Abstract163)      PDF(pc) (361KB)(110)       Save
Based on the investigation of Guohua Yongfa wind farm, this paper optimized the control strategy of the refined control model algorithm based on the optimal blade tip speed ratio tracking for the problems existing in 1.5MW wind turbine, including: speed and torque optimization, blade pitch angle dynamic control strategy, yaw optimization strategy, rotor pitch bearing wear and high wind operation protection, etc. Optimizing the cut-in wind speed and related parameters, and optimizing the start-stop control mode and adjust the initial angle of blade installation, at the same time, studied the wind turbines supervisory control and data acquisition(SCADA) transformation technology, solved the problem of frequency converter product upgrade and replacement and put forward the improvement strategy of improving unit safety and reliability. Through the implementation of corresponding countermeasures, the generation capacity and availability of wind power units have been significantly increased, reaching the expected effect, accumulating valuable on-site application engineering experience, and laying a solid foundation for the promotion and application of the project.
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Power Control and Voltage Fluctuation Suppression Strategy of the Bidirectional AC/DC Converter in the Islanding Hybrid Microgrid
LIU Ziwen, MIAO Shihong, FAN Zhihua, KANG Yilong, CHAO Kaiyun, SUN Dandan
Proceeding of the CSEE    2019, 39 (21): 6225-6237.   DOI: 10.13334/j.0258-8013.pcsee.180279
Abstract162)      PDF(pc) (554KB)(172)       Save
In islanding hybrid AC/DC microgrid, a well-designed control of the bidirectional AC/DC converter can achieve independent power distribution and improve the anti-interference ability of AC and DC buses. In this paper, through the equivalence of AC and DC subgrids in the hybrid microgrid to the integrated source, the active power droop control equation of the AC side and DC side of the bidirectional AC/DC converter was given. Then proportional sharing based outer loop power control strategy was proposed to realize the power balance and independent allocation in the hybrid microgrid. Meanwhile, owing to that the convention inner loop PI control cannot get ideal voltage dynamic response, the voltage fluctuation of the bidirectional AC/DC converter was analyzed. Then an improved inner loop control strategy based on the disturbance observer and disturbance suppression was proposed, which can track the reference value with no steady error and improve the robust stability of the microgrid. Simulation results show the validity and efficiency of the proposed control strategies.
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Sequence Impedance Modeling and Analysis of Permanent Magnet Synchronous Generator Considering Machine Side Model
LI Guanghui, WANG Weisheng, ZHANG Xing, LIU Chun, HE Guoqing
Proceeding of the CSEE    2019, 39 (21): 6200-6211.   DOI: 10.13334/j.0258-8013.pcsee.182447
Abstract155)      PDF(pc) (1189KB)(187)       Save
Permanent magnet synchronous generators (PMSG), as the mainstream type of wind power, have frequent oscillation phenomena. Sequence impedance model has gradually become a widely used method to analyze large-scale grid-connecting wind power oscillation issues. The sequence impedance model of PMSG built previously simplifies the machine-side model (including machine-side converter (MSC) and generator) as a current source, ignoring the influence of machine-side model on the impedance characteristic of PMSG. In this paper, a detailed analytical impedance model of PMSG considering generator, MSC, DC-bus dynamic process, DC-bus voltage control loop and grid-side converter (GSC) was established, revealing the frequency characteristic and distribution of the small-signal components in PMSG. Then the influence of MSC control characteristic, DC-bus capacitance and DC-bus voltage control characteristic on the impedance characteristic was studied. Based on the control-hardware-in- the-loop (CHIL) real-time simulation, the accuracy of the proposed detailed model was verified. Then the impedance scanning and stability analysis of several practical PMSGs were carried out. The effect of the machine-side model on the PMSG impedance characteristic was verified.
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Overview of Arc High Impedance Grounding Fault Detection Technologies in Distribution System
WANG Bin, CUI Xin, DONG Xinzhou
Proceeding of the CSEE    2020, 40 (1): 96-107.   DOI: 10.13334/j.0258-8013.pcsee.190815
Abstract154)      PDF(pc) (430KB)(220)       Save
The fault electrical quantity is relatively weak with the arc high impedance grounding fault in feeders no matter in the neutral effective or non-effective grounding distribution systems, the traditional fault detection methods often fail. To solve this problem, the unified model of arc high impedance grounding fault in feeder was established according to different neutral grounding modes, and the zero-state response characteristics generated under the excitation of virtual power supply at fault point were analyzed. Based on the above analysis, the detection methods of arc high impedance grounding fault in feeders under two neutral grounding modes were reviewed and summarized from the perspectives of steady-state frequency domain analysis, transient-state time domain analysis, traveling wave analysis, artificial intelligence, etc. In addition, the following research ideas are put forward from such aspects as harmonic wave fluctuation, line selection starting criterion, wave head recognition and arc waveform distortion.
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Analysis and Reflection on the Marketization Construction of Electric Power With Chinese Characteristics Based on Energy Transformation
CHEN Guoping, LIANG Zhifeng, DONG Yu
Proceeding of the CSEE    2020, 40 (2): 369-378.   DOI: 10.13334/j.0258-8013.pcsee.191382
Abstract154)      PDF(pc) (370KB)(264)       Save
With the continuous deepening of China’s energy clean transition and the acceleration of power market construction, it is necessary to combine the development needs and actual national conditions to fully stimulate the market’s competitive vitality and build a power market with Chinese characteristics on the premise of ensuring the safe operation and green development of the power grid. This paper summarized the needs and trends of China’s energy development, analyzed the changes of power system characteristics and the impact of power market operation under the new situation. On the basis of summarizing the previous practice and achievements, it studied the challenges faced by China’s power market construction and proposed the principle of energy market construction with Chinese characteristics and several key issues.
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Joint Optimal Operation and Bidding Strategies of Concentrating Solar Power Plants With Wind Farms
FANG Yuchen, ZHAO Shuqiang
Proceeding of the CSEE    2020, 40 (1): 39-49.   DOI: 10.13334/j.0258-8013.pcsee.190019
Abstract153)      PDF(pc) (2275KB)(188)       Save
As the most promising renewable energy utilization technologies, concentrating solar power (CSP) utilizes thermal energy storage (TES) to make solar energy a scheduling resource without increasing uncertainty of the system. At the same time, the CSP plant has flexible regulation characteristics, which can cooperate with wind power to reduce the uncertainty of output and improve the consumption capacity of renewable energy. This paper analyzed the energy storage characteristics of the CSP plant and established a joint optimal operation and bidding model for CSP plants and wind farms. The model illustrates the components of the CSP plant in detail and takes into account the effects of renewable energy output and market price uncertainty. In order to increase the flexibility of the power system and the revenue of the joint system, the CSP plant was assumed to participate in the auxiliary service market bidding and providing the reserve capacity for the wind farm to counteract the output fluctuations. Finally, the validity of the model was verified by the case study, and the advantages of the joint bidding strategy were illustrated through the comparison with the single bidding strategy.
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A Review on Modeling of Switching Converters and Their Control Loops
ZHOU Guohua, LENG Minrui, LI Yuan, TIAN Qingxin, DENG Lunbo
Proceeding of the CSEE    2020, 40 (1): 183-199.   DOI: 10.13334/j.0258-8013.pcsee.182603
Abstract153)      PDF(pc) (708KB)(312)       Save
Modeling methods of switching converters and their control loops were summarized and concluded. Meanwhile, classifications for modeling methods of switching converters were given: continuous modeling and discrete modeling; modeling methods based on circuit analysis and modeling methods based on mathematical derivation. According to these classifications, modeling methods of switching converters and their control loops can be combined and further classified as: average modeling, discrete modeling and modeling methods considering sideband effects. On the basis of this classification, principles and characteristics of average method, discrete time method, sampled-data method, describing function method, multiharmonic small signal method and harmonic state space method were analyzed systematically. The differences and relations of various modeling methods were revealed, as well as their merits and demerits were compared which illustrated the applicability of various modeling methods. Taking the most widely used average method as an example, firstly, the equivalent circuit model of basic switching converter was obtained based on time average equivalent circuit modeling, and eight complete transfer functions of power stage were deduced. Moreover, the general gain of sample and hold effect was proposed to figure out that average model ignored the subharmonic oscillation and the traditional gain cannot be used in different average small signal model. Finally, review conclusions and research prospects were presented.
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Analytical Analysis on the Active Power Control Stability of the Weak Grids-connected VSC
WU Guanglu, WANG Shanshan, ZHOU Xiaoxin, ZHAO Bing, LIANG Jun, LI Yingbiao, WANG Tiezhu
Proceeding of the CSEE    2019, 39 (21): 6169-6182.   DOI: 10.13334/j.0258-8013.pcsee.190232
Abstract150)      PDF(pc) (611KB)(301)       Save
First of all, the analytical multi-input multi-output(MIMO) transfer function model of the weak grids-connected VSC was derived in consideration of the AC system strength and the effect of the phase-locked loop(PLL). Then, a novel method was proposed to simplify the MIMO model to a single-input single-output(SISO) model by setting one reference to zero. Then, the SISO open loop transfer function GPC0 of the active power control(APC) can be rearranged as the products of an ideal transfer function GPC0_1 and a modulation function GPC0_2. The GPC0_1 presents the impact of the APC of the infinite system-connected VSC, while the GPC0_2 presents impacts of the AC system strength, the active power, the PLL’s bandwidth and the AC voltage control’s bandwidth. The APC stability of the weak grids-connected VSC can be analyzed by studying the impact of the modulation transfer function on the phase margin of the ideal transfer function. The phenomenon that the system is more likely to lose stability when the PLL and the APC have adjacent bandwidths in weak grids condition, was explained. The impacts of the AC system strength, the active power and the AC-voltage control’s bandwidth on system stability are also investigated. The theoretical analysis was validated by simulation results.
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Route Planning and Charging Navigation Strategy for Electric Vehicles Based on Real-time Traffic Information
XING Qiang, CHEN Zhong, LENG Zhaoying, LU Yu, LIU Yi
Proceeding of the CSEE    2020, 40 (2): 534-549.   DOI: 10.13334/j.0258-8013.pcsee.182001
Abstract147)      PDF(pc) (1338KB)(198)       Save
Aiming at the characteristics of electric vehicles combined with transportation and mobile load, which charging behavior and driving characteristic will have interactive effects on the transportation system and the grid system. On the basis of this, a route planning and charging navigation strategy for electric vehicles based on real-time traffic information was presented in this paper. First, the advantage of the model with time-division was determined by comparing and analyzing the dynamic traffic network models, and the “time-flow” road resistance model considering road impedance and intersection node impedance was proposed according to the characteristics of urban roads. Second, based on the establishment of traffic network model, distribution network model and single electric vehicle model, a multi-objective optimization function integrated with the road travel time, the charging station load and the quantity of vehicles entering the station was determined, which was solved to recommend optimal driving and charging paths by adopting the modified adaptive Dijkstra dynamic search algorithm. Finally, the actual road network of a certain area in Nanjing was selected as an example to introduce the scale of electric vehicles into different regions according to the traffic flow situation and resident trip rule. With the above information, the travel behavior of EVs was simulated by the origin-destination method, the impact of electric vehicle charging and driving behaviors on transportation network and distribution network was analyzed as well. Simulation results demonstrate its effectiveness and feasibility.
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Power Oscillation Damping Control for Microgrid With Multiple VSG Units
HONG Haohao, GU Wei, HUANG Qiang, CHEN Liang, YUAN Xiaodong, WANG Jianhua
Proceeding of the CSEE    2019, 39 (21): 6247-6254.   DOI: 10.13334/j.0258-8013.pcsee.181088
Abstract147)      PDF(pc) (768KB)(260)       Save
Most of distributed generations in microgrid are lack of inertia, which results in poor frequency stability. To solve this problem, virtual synchronous generator (VSG) control method is proposed to simulate the characteristics of synchronous generator. However, active power oscillation is introduced under basic VSG control, which would be more serious when multiple VSGs operate in parallel. In this paper, a control strategy based on mutual damping under distributed communication (MDDC) was proposed, with which the power oscillation was restrained effectively and the dynamic characteristics of VSG was improved. Furthermore, the stability of the improved system was analyzed and proved by Lyapunov function. Finally, a real-time simulation platform based on RT-LAB was built to verify the proposed control strategy.
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Development of Intelligent Perception Key Technology in the Ubiquitous Internet of Things in Electricity
ZHOU Feng, ZHOU Hui, DIAO Yinglong
Proceeding of the CSEE    2020, 40 (1): 70-82.   DOI: 10.13334/j.0258-8013.pcsee.191198
Abstract146)      PDF(pc) (830KB)(404)       Save
Intelligent sensing is the data entry of the ubiquitous internet of things, and plays an extremely important role in the construction of the ubiquitous internet of things. This paper quantitatively compared the advantages of the ubiquitous internet of things in electricity in data transmission capacity by abstracting the information theory expression of the ubiquitous internet of things in electricity, and estimated the scale of intelligent perception network synthetically, forecasting solving the problems needs massive multi-source data fusion and information security protection. This paper proposed decomposition and subsidence coefficient of edge algorithm for the ubiquitous internet of things in electricity, defined a paradigm describing the decomposability of edge algorithm, illustrated the computational efficiency of common electric power algorithms after edge decomposition of ubiquitous internet of things, and discussed the information gain of intelligent perception in space-time, type and accuracy. Based on this, the development ideas of ubiquitous intelligent perception technology in three dimensions of data access network, edge computing and depth computing were described respectively. On this basis, the practical application scenarios of the ubiquitous internet of things in electricity were discussed.
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Itô Stochastic Process Model for Renewable Generations
CHEN Xiaoshuang, LIN Jin, LIU Feng, SONG Yonghua
Proceeding of the CSEE    2020, 40 (1): 83-95.   DOI: 10.13334/j.0258-8013.pcsee.190194
Abstract143)      PDF(pc) (745KB)(234)       Save
With the increasing penetration of renewable energy generations, the uncertainties of these generations bringsignificant influences on power system operations and control. The Itô process is an important tool in the analysis of stochastic dynamic systems. It models the uncertainties of renewable generations as stochastic differential equations, which is consistent with the ordinary-differential-equation model of the dynamics of power systems. Therefore, the Itô-process model makes it easier to analyze the impacts of uncertainties on power system dynamics. Power system analysis and control based on the Itô-process model achieve success in many areas, such as stability analysis, security analysis, optimal control, etc. However, it is still an open problem whether the Itô-process model can describe the stochastic characteristics of renewable generations accurately, which is very fundamental in power system analysis and control based on Itô processes. Under this background, this paper discussed the ability of Itô processes to describe the uncertainties of renewable generations thoroughly. On the one hand, we proved that the Itô-process model can be used to accurately describe the probability distribution, the temporal and spatial correlation of renewable generations; on the other hand, this paper proposed a parameter estimation method of the Itô-process model in order to obtain the parameters based on historical data. Case studies show that the Itô-process model can be compatible with existing models of renewable generations, and can be estimated in a data-driven manner, thus providing a modeling basis for the further applications of the Itô process in the power system.
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Optimum Design of Planer Busbar Based on All-silicon Carbide Power Module
ZHU Junjie, YUAN Jingxin, NIE Ziling, XU Wenkai, HAN Yi
Proceeding of the CSEE    2019, 39 (21): 6383-6393.   DOI: 10.13334/j.0258-8013.pcsee.190614
Abstract139)      PDF(pc) (601KB)(230)       Save
In order to reduce switching oscillation of all- SiC power modules and meet the application requirements of high power density for power devices. The layouts of three-phase two-level topological planer busbar elements were analyzed quantitatively, and a mathematical model of planer busbar elements considering self-inductance and mutual inductance was established. Based on the mathematical model, the equivalent values of stray inductance of the planer busbar circuit corresponding to a single capacitor and two capacitors were calculated. The equivalent stray inductance of the planer busbar circuit corresponding to the capacitance above was calculated and simulated. The results show that with the increase of the number of supporting capacitors, the stray inductance of the circuit decreases gradually, and the consistency is better. By analyzing the stray inductance of each branch, the layout of DC bus port was optimized, and the effect of restraining switching oscillation was verified by double pulse experiment. The experimental results show that although the switching time and switching loss of the optimized power module increase, the switching oscillation can be effectively suppressed, which can better meet the security requirements of high power density applications.
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Matrix Model of Nonlinear Single-port Network for General Harmonic Sources
GE Xinliang, LIU Youwei
Proceeding of the CSEE    2019, 39 (21): 6255-6262.   DOI: 10.13334/j.0258-8013.pcsee.182198
Abstract138)      PDF(pc) (317KB)(162)       Save
In view of the difficulties in modeling harmonic source, the low accuracy of existing models and the limited scope of application, a general nonlinear single-port network model for harmonic sources was derived theoretically in this paper. Based on the differential equation of voltage and current in time domain, the coupling relationship in frequency domain was deduced, and the voltage- controlled model and the flow-controlled model of the nonlinear single-port network were established. Aiming at unknown parameters of nonlinear components and network topology in engineering practice, the numerical solution of model parameters was given in this paper. Finally, in the environment of MATLAB/Simulink, the harmonic source networks with different complexity were established to test the model, and the accuracy of the model was much higher than the existing Norton equivalent model and crossed frequency admittance matrix model. The simulation results show that the proposed model is suitable for harmonic source networks with different nonlinear characteristics and network topologies, and has high accuracy and convenient parameter solution.
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A Review on Grid-friendly Control Technologies for Wind Power Generators
CHENG Peng, MA Jing, LI Qing, WANG Weisheng
Proceeding of the CSEE    2020, 40 (2): 456-466.   DOI: 10.13334/j.0258-8013.pcsee.190243
Abstract137)      PDF(pc) (438KB)(192)       Save
The grid-friendly control strategy has been regarded as a serviceable approach of achieving the flexible interaction between the wind power generators and the power system. By flexibly regulating the voltages/currents, the wind power generators can be controlled to be helpful to the power balance. As a result, the grid-friendly operation of the wind power generator was fulfilled. From the viewpoint of the function dimension, the frequency dimension and the time dimension, the typical characteristics of the grid-friendly control strategies for wind power generators were presented. Then, in order to present the lasted progress in the grid-friendly control strategies, the control strategies on the voltage coordination and the current regulation were reviewed and compared. Finally, the possible future development of the grid-friendly control strategies was discussed.
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Research on Short-term Load Forecasting Variable Selection Based on Fusion of Data Driven Method and Forecast Error Driven Method
ZHENG Ruicheng, GU Jie, JIN Zhijian, PENG Hongqiao, CAI Long
Proceeding of the CSEE    2020, 40 (2): 487-499.   DOI: 10.13334/j.0258-8013.pcsee.181740
Abstract136)      PDF(pc) (1258KB)(190)       Save
Short-term load forecasting is the basis for the safe and economic operation of power system. Since electrical load is affected by many factors, choosing proper variable set is critical to improving forecasting performance. Owing to the characteristics of data driven variable selection(VS) method and forecast error driven VS method and the problems of traditional VS methods in correlation metrics and selection strategies, this paper proposed VS of orthogonal maximal information coefficient, feature interaction and random forest(OMICFI-RFVS). The method combines data driven method and forecast error driven method in two stages. The former was used as the variable pre-screening stage, and the latter completes the further VS. The method achieves the balance between selection quality and computational complexity. The method comprehensively considers the relevancy, redundancy and synergy between variables, which can effectively improve the forecasting performance. The advantages of OMICFI- RFVS were verified by cases from the selected variable set, forecast error and forecast error stability.
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A Review on the Utilization of Energy Storage System for the Flexible and Safe Operation of Renewable Energy Microgrids
LIU Chang, ZHUO Jiankun, ZHAO Dongming, LI Shuiqing, CHEN Jingshuo, WANG Jinxing, YAO Qiang
Proceeding of the CSEE    2020, 40 (1): 1-18.   DOI: 10.13334/j.0258-8013.pcsee.190212
Abstract135)      PDF(pc) (566KB)(334)       Save
Energy storage is a key technology to protect the safe and stable operation of microgrids, and has become one of the important measures to promote commercial application of renewable energy microgrids. In this paper, after analyzing the technical characteristics of renewable energy microgrids, the role, classification, design optimization and application of energy storage systems in microgrids were thoroughly reviewed. The results show that a joint optimization method for energy storage and demand response can effectively improve the economy, reliability and comprehensive utilization of energy of microgrid. By comprehensively evaluating energy density, power density, response time and rated power, the applicability of different energy storage technologies in microgrid can be obtained. Energy storage technology has an important application prospect in the flexible operation of microgrid.
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Transformerless High-voltage Power Conversion System for Battery Energy Storage System and the First Demonstration Application in World
CAI Xu, LI Rui, LIU Chang, CHEN Qiang, LI Xiaolin, LEI Bo, CHEN Man, LI Yongqi, GUO Haifeng, LI Jianlin, YANG Bo, GAN Jianghua, LI Guanjun
Proceeding of the CSEE    2020, 40 (1): 200-211.   DOI: 10.13334/j.0258-8013.pcsee.182511
Abstract132)      PDF(pc) (1384KB)(239)       Save
Comprehensive argumentation and evaluation of the key issues of the transformerless cascaded H-bridge converter applied in battery energy storage system (BESS) were performed from the aspects of topology, control, and design and experiment verification. A unified balance control scheme was proposed in this paper, which reduced the complexity of the whole control scheme and integrates the control under unbalanced grid voltage, module fault-tolerant control and interphase state of charge (SOC) balancing control together. In order to verify the feasibility of the proposed control scheme, a downscaled experimental prototype was built up in the laboratory. The suppression of common-mode current among modules and the second-order rippled current of the battery were discussed in detail. Then, the optimal design method of the cascaded H-bridge converter for BESS was proposed. We have designed a 10kV/2MW/2MW•h battery energy storage system based on cascaded H-bridge converter (CHBC-BESS). Supported by the national high technology research and development of China 863 program, the first practical engineering demonstration application was performed at the Baoqing energy storage power station in Shenzhen in 2014. We has accumulated rich experience and operatingdata in practice, which lays a foundation for the promotion and application of CHBC-BESS.
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