All posters are displayed during the two conference days and can be viewed anytime. The poster session & time here is only used for programming & information purpose.
Among all kinds of power quality problems, voltage sag has the most serious impact on the production of users. In recent years, the research on voltage sag is one of the hotspots in the field of power quality.This paper systematically analyses the causes of voltage sag and its typical characteristics;By comparing and analyzing the existing optimal allocation methods of voltage sag monitoring points, it is pointed out that the current optimal allocation of voltage sag monitoring points generally depends heavily on voltage sag threshold and neglects fault resistance;The time-frequency analysis method and non-time-frequency analysis method in voltage sag detection are elaborated. The shortcomings of current voltage sag detection methods are pointed out. The advantages and disadvantages of improved S-transform are compared and analyzed emphatically;This paper analyses the methods of voltage sag control from three aspects: power supply side, user side and equipment manufacturer side. It is proposed that the integrated control based on the relationship between the three methods is more effective, and the research on the integrated control of voltage sag is prospected.
Currently studying in Nanjing Institute of Technology, the research direction is voltage sag.
In order to investigate the icing condition of the transmission line which across the micro-geography and micro-meteorological, in this paper, on the basis of micro-meteorological theory, the regression model between meteorological factors is established by the multiple regression analysis method, taking three transmission lines which with typical micro-geography distribution in North China Grid and occurred accidents in history as an example. The results show that the method can reveal the relationship between micro-meteorological parameters from a quantitative angle and make the meteorological analysis and prediction of transmission lines in micro-geography environment more accurately. It lay a foundation for real-time evaluation of electrical reliability of transmission lines and the establishment of early warning system. In this paper, a micro-meteorological prediction system for transmission lines is developed by using MATLAB GUI. Three typical transmission lines of the micro-topography distribution in North China Power Grid, namely X 1st & 2nd, Y line, are applied for example application. The calculation results are compared with the historical micro-meteorological parameters of the lines. The results show that the micro-meteorological parameters obtained by using the prediction model are basically consistent with the actual situation of the lines, and the accuracy and practicability of the prediction model can be verified to some extent.
Li Longji (1986-), mylongji@tsinghua.org.cn, male, master, senior engineer, engaged in high voltage transmission technology, external insulation technology, state maintenance and fault diagnosis technology, new energy power generation and numerical control technology research.
In this paper, an automatic configuration method of reactive power compensators is proposed based on modified DC power flow and reinforcement learning (RL). The node voltages are estimated by the modified DC power flow algorithm. A reinforcement learning algorithm is proposed to make configurations of reactive power compensators on the basis of a rule-based reactive power compensators adjustment framework. Simulations on IEEE 300-bus system and matpower 9241-bus system have proved the feasibility and effectiveness of the proposed method.
Songtao ZHANG is a Ph.D student from China Electric Power Research Institute.
With soft normally open point (SNOP) putting into the distribution network, it not only realises the interconnection between the distribution networks with different voltage levels and feeders with different phases, but also provides the practicability for the non-stop load transfer. There are great need to achieve the operation of SNOP with an accurate state. Therefore, this paper proposes a state estimation model of the flexible distribution network based on the quadratic constrained quadratic problem (QCQP). This model considers the three-phase unbalance characteristics of the distribution network and the transmission loss of SNOP. Besides, the corresponding measurement equations and constraints can ensure the observability of state estimation. Finally, Numerical tests on the flexible distribution network with SNOP show that this state estimation method is utilitarian and efficient.
Xin Ma received the B.S. and M.S. degrees from Zhejiang University, Hangzhou, China, in 2012 and 2016, respectively, all in electrical engineering. Now, he is an engineer in the Electric Power Research Institute of State Grid Ningxia Electric Power Company. His research interests include the operation of the distribution network.
A comprehensive compensation method of negative sequence and harmonic for co-phase traction power supply system in electrified railway with Dd transformer and static var generator (SVG) is presented in this paper. With this method, not only can the comprehensive compensation of negative sequence and harmonic be realized, but also the potential safety hazards can be reduced when a locomotive passes through the neutral section. Taking Dd0 transformer as an example of Dd transformer, topologies of the comprehensive compensation schemes are presented in detail, which are divided into compensation mode I and compensation mode II. From the perspective of mathematical analysis, mathematical model of the comprehensive compensation is deduced in detail, and the basic principle of comprehensive compensation is revealed. Based on the mathematical model, the method to determine the compensation scheme is given. Aiming at the comprehensive compensation methods of mode I and mode II, the closed-loop control strategies for compensation mode I and mode II are proposed respectively. Finally, effectiveness and accuracy of the method and control strategies proposed in this paper are verified by the simulation models.
Hui Wang，received the B.S. degree and M.S. degree from Southwest Jiaotong University, China, in 2014 and 2017. Currently, he is pursuing the Ph.D. degree in electrical engineering at Southwest Jiaotong University. His research interests are theory of traction power supply system and power quality.
The Zhejiang Province is in the temperate maritime climate with the geographical characteristics of mountains and hills. Thus it lies in the thunderstorm prone area which caused many troubles to the power grid. The statistical distribution of lightning is an important basis for the scientific research of lightning. Based on the data of lightning flash monitoring in Zhejiang Province from 2010 to 2018，The spatial-temporal features of these lightings are statistically analyzed. A total of more than 3.8 million Lighting strikes are observed in Zhejiang Province from 2010 to 2018. An in-depth data mining of these data could provide useful information for lightning protection. Moreover，The characteristics of the500kV transmission line lightning stroke are also presented,the high incidence lightning area and power transmission line corridor are proposed．
Zhenguo Wang, born in Shandong province in 1989, Doctor of electrical engineering. Research areas include transmission line disaster prevention and mitigation and corona discharge.
Due to the limitation of the simulation step size, the traditional electromechanical transient simulation tool is difficult to accurately simulate the dynamic behaviour of the power electronics devices. Large-scale power grids with power electronics need to be simulated using EMT simulation. Due to its small simulation step size, complex models, EMT simulation performs huge computational complexity and is very challenge to be used in large-scale power grid simulation. The entitle power grids will be divided into subgroups by the Transmission Line. The subgroup divided by Transmission Line is wholly decoupled which requires synchronization in a separate step. Therefore, the subnetworks in a group requires large amount of information, while the groups will be synchronized with limited information. This paper proposes the hierarchical communication to handle this complex communication requirement and speed up the entire communication time. The algorithm proposed in this project can realize ultra-real-time simulation of 7000-node large-area power grid.
Qing Mu is specialized in the simulation of Power system and Power Electronics. He got Phd. at CEPRI in 2013, and studied in Cardiff University from 2015-2016 as Marie Curie Researcher. Currently, he is developing ADPSS, which is a dominated simulation tool in China power industry.
With the rapid growth of economics, power quality issue represented by voltage sag has increasingly captured considerable attention from both utility companies and their customers. Continuous voltage sag results in the operation of under voltage load shedding (UVLS), seriously influencing the system security and service reliability. Based on energizing typical 1000 kV no-load transformer located in UHV network in North China Power Grid, the mechanism of voltage sag caused by energizing no-load transformer was analysed and it was proposed that the inrush current was an important factor influencing the voltage sag. The voltage sag caused by the oscillating inrush current is discussed. And the influence factors and suppression measures on the voltage sag are studied. It is proposed to install large-capacity dynamic reactive power compensation device Static Var Generator (SVG) to mitigate voltage sag in energizing no-load transformer. And to verify the effectiveness of SVG to mitigate voltage sag in energizing no-load transformer, a typical model of the analysis system based on PSCAD/EMTDC has been built, both theoretical analysis and simulation results show that this method is effective.
Hongli Jiang received the B.S. degree from Beihang University, Beijing, China, in 2013 and M.S. degree from Tsinghua University, Beijing, China, in 2016, respectively. Currently, he works as an Engineer with China Electric Power Research Institute, Beijing, China. His research interests include power system stability analysis and control, modelling and performance studies of wind farms and FACTS.
In recent years, power system failure events caused by high-risk and low-probability extreme events have occurred frequently in the world, and resilience is used to describe the system's ability to adapt and recover from extreme events. In order to accurately evaluate the resilience of the distribution network, resilience metrics and evaluation method considering the system operation duration and risk are proposed and verified. Firstly, the resilience metrics of the distribution network considering the operation duration and risk are proposed. Then, The probability distribution of different distributed renewable energy sources and loads is fitted by kernel density estimation(KDE) method. To reflect the uncertainty of distributed renewable energy and load, the scenes are generated by Latin hypercube sampling(LHS) and cholesky method, and simultaneous backward reduction(SBR) method is used to reduce the generated scenes. Secondly, a two-layer optimization model of system operation duration and operational risk, which takes into account the uncertainty of renewable energy generation is proposed. According to the internal and external evaluation results, the resilience of the system under a given risk constraint can be evaluated. Finally, based on the improved IEEE33 node system, the proposed metrics and methods are verified, and the system resilience under different risks is analyzed.
Shizhong Zhang is a PhD student at the institute of electrical engineering, Chinese academy of sciences . His research interests include distribution system resilience and AC-DC hybrid distribution network.
Abstract
All 10kV distribution network systems in China adopt non-effective grounding. With the expansion of distribution network scale and the increase of nonlinear load, the earth fault current and the harmonic content increases. The earth fault arc difficult extinguish by itself.Some scholars put forward an arc extinction technology that USES circuit breaker to transfer the fault to the substation. However, this technology may cause potential rise in the station due to excessive fault current, it may cause safety risks to the control and protection equipment.In this paper, A voltage arc extinction method for the combination of single-phase cascade h-bridge converter and vacuum circuit breaker is proposed. Three single-phase vacuum circuit breakers are respectively connected to A, B and C phases. When the fault occurs, the closed corresponding circuit breaker is connected to the ground fault for transfer.A double closed-loop control system is constructed to track the ground fault current in real time based on the deadbeat control method, so as to realize the full compensation of ground fault current and eliminate the ground potential rise.Through rt-lab simulation platform, a 10kV distribution network model was built. The arc extinction method proposed in this paper was simulated and analyzed in the case of arc light and high resistance grounding. It was verified that it could effectively suppress arc light grounding fault and solve the problem that the traditional failover device could not flexibly control zero-sequence current.
Key words: Distribution Network , H-bridge ,Double Closed-loop Control, Without Difference Beat Control, Rt-lab
Chen Weidong, male. People's Republic of China Lingyuan City, Liaoning Province, in Shenyang University of Technology School of Electrical Engineering, second grade. Professional direction is power system and its automation. In Liaoning Province High Voltage and Power System Research Institute engaged in active distribution network, AC-DC hybrid microgrid, DC distribution network protection, multi-energy interconnection research. Has participated in the distribution network single-phase arc-optical grounding active arc suppression, polymorphic complex conditions of distribution network line selection research, modular photovoltaic DC boost and other related topics.
To avoid numerical inaccuracy by the time-domain solvers or high-frequency oscillatory integrals by the frequency-domain solvers when calculating the lightning transient in GIS grounding grids, this paper proposes an alternative and stable approach base on the frequency-dependent and wide-band transient modelling of grounding grid and the simultaneous extrapolation approach using the local linear basis. According to the circuit theory and the electromagnetic field theory, the transient model of grounding grids with its parameters can be obtained and meanwhile the frequency-dependent parameters are transferred by vector fitting method in the process. Thus, the early time and low-frequency data under the lightning are also available through the model. Combining the early time response and low-frequency spectrum, the full response is extrapolated by simultaneous extrapolation approach and the analysis of two key factors, the evaluation of early-time and low-frequency truncation and the method of singular value decomposition (SVD), are conducted. This approach is then applied to extrapolate a 6-by-6 transient grounding grids case under the lightning and the results are compared with the one simulated by EMTP/ATP. The comparisons show the feasibility and accuracy of the simultaneous extrapolation approach for calculating the lightning transient in grounding grids. At the same time, the early truncation time needs to be chosen to include the peak response and the low-frequency truncation frequency should be determined correspondingly.
Jun Zou received his Ph.D. degree from Tsinghua University, Beijing, China in electrical engineering. In 2001, he joined electrical engineering department of Tsinghua University and In 2011, he was promoted to be a full professor. Dr. Jun Zou has been involving in researches on EMC in power systems, computational electromagnetics.
The body feeling of different insulation effects under AC and DC transmission line is analyzed in this paper.The results could provide a reference for evaluating the electromagnetic environment of AC and DC transmission lines. Firstly, the different types of the body feeling under AC and DC transmission lines is analyzed. The main body feeling under the AC electric fields is the steady-state feeling of the body in the electric fields. The main body feeling under the DC transmission line is the transient electric shock. Secondly, an three-dimensional finite element model of transmission lines and a simplified human body model is established in COMSOL. This paper calculated the induced potential, induced current density and electric field of the human body under different states of insulation. The result shows that wearing the shoes make the body induced voltage increase significantly. Finally, the transient electric shock of different insulation states under the DC transmission line is analyzed in this paper. The model of DC transmission line and human body is built in the laboratory, and the transient electric shock under different insulation states is simulated. The body's discharging waveform can be used to evaluate the body feeling. The experiment results can provide technical support for the safe operation and maintenance of DC transmission lines.
Bin Yang is currently an engineer in State Grid Shaanxi Electric Power Research Institute. She received a B.S.and an M.S. from Xi’an Jiaotong University in 2012 and 2015.Her current research focuses on electromagnetic environment of the AC and DC power system.
The application of a large number of nonlinear, impulsive and fluctuating loads makes the power grid environment more complex, which will generate unsteady signals. The traditional energy measurement algorithm is suitable for harmonic and other steady-state signals, but it is not accurate enough for unsteady signal. In order to realize the accurate measurement of the electric energy of the unsteady signal, this paper proposes an algorithm of the electric energy measurement based on the S-transform. Firstly, the voltage and current signals are sampled, and the S-transform is performed after the unsteady signal are obtained. Then the power matrix is obtained by multiplying the S-transform result matrix, and then the extreme value is taken, and finally the electric energy is obtained. Finally, through the simulation of steady-state signal and unsteady signal, it shows that the algorithm is not only suitable for calculating the electric energy of harmonic steady-state signal, but also suitable for calculating the electric energy of unsteady signal.
My name is Ni Weilun, studying in the school of electrical engineering, Shanghai University Of Electric Power, China. I am a postgraduate male student majoring in power system and automation. My research direction is power metering. My research topic is power metering in complex power environment. The title of the paper I submitted in this meeting is Study On The Method Of Electric Energy Measurement For Unsteady Signal. With the increasing complexity of the power environment, the power grid signal appears the characteristics of unsteady state, randomness and volatility, which will have a great impact on the power measurement. This paper discusses and studies this problem.
The Power Flow Convergence (PFC) adjustment is an essential issue in the study of power system Operation State Calculation (OSC). Currently, as the grid structure expands markedly, the PFC adjustment is realized by adjusting the regional active and reactive power manually in most dispatching centres, which is tedious and personnel-experience oriented. Therefore, it is crucial to automate the PFC adjustment for efficiency and quality improvement. In this paper, an improved deep reinforcement learning (IDRL) based method and an action-executing strategy are proposed for the automation of the PFC adjustment. The optimal configuration scheme of the adjustable generators is derived from the trained online Q network for multi-load levels. Finally, the testing results on the IEEE-118 bus system demonstrate that the proposed method can obtain the convergent power flow state according to the given load level effectively.
Huating Xu received his B.S. degree in electrical engineering and its automation from Sichuan University. He worked as an electrical engineer in China General Nuclear Power Group from 2012 to 2017. He is presently working towards his M.S. degree in China Electric Power Research Institute. His current research interests include deep reinforcement learning, reactive power and tie-line power adjustment, optimal power flow, and multi-agent system.
Transmission line project is an important link of power grid construction stage. The refined prediction of line project cost can help and promote project evaluation, budget formulation, capital audit and other aspects. Intelligent model has been widely used in the modeling process of line engineering cost prediction. This paper describes the establishment process of two classical intelligent algorithm prediction model in detail, compares the advantages and disadvantages of neural network and support vector machine prediction model, and analyzes the applicable fields of the two methods. The application of K-means clustering, hierarchical clustering and fuzzy clustering in the field of prediction have been described. Three clustering methods are used to improve the prediction accuracy of neural network and support vector machine intelligent algorithm. In this article a method of comprehensive intelligent prediction of transmission line project cost based on clustering is proposed. Taking the cost of 90 groups of 110kV transmission line projects newly built in 2017-2018 of a block power grid as the data source for example verification. The experiment shows the comprehensive clustering of data sources can significantly improve the accuracy of the application of neural network and support vector machine algorithm in the price prediction of transmission line projects. All of the prediction errors are less than 20%. Hierarchical clustering has the most significant effect on reducing the error of neural network algorithm, while fuzzy clustering has more obvious effect on improving the accuracy of SVM algorithm.
Hao Li, received the B.S. degree and M.S. degrees in electrical engineering from Shandong University. He is an assistant engineer of ECONOMIC&TECHNOLOGY RESEARCH INSTITUTE. STATE GRID SHANDONG ELECTRIC POWER COMPANY, Jinan, China. His research interests are power system distribution network planning, distribution network project review and dynamic simulation of power system.
With the fast development of renewable energy generation, the randomness and volatility seriously threaten the stability of the power system. In order to improve the consumption rate of renewable energy and the economic benefit, the source-network-load collaborative optimization is put forward and widely used in the power system. And the active power distribution network which consists of the energy storage devices and flexible load is the best carrier to realize it. Based on the active power distribution network planning, this paper firstly designs an economic index covering construction cost and operation cost as the optimization objective. Then with the physical constraints consisting of the physical features of generation units, energy storage devices and flexible load, the source-network-load collaborative optimization model of active power distribution network is established. Finally, a case of city distribution network is presented to verify the effect of source-network-load collaborative optimization and the efficiency of the optimization model.
Jiang Zhicheng was born in Zhejiang, China on July 9, 1997. He received B.S degree from Tsinghua University in 2019. He is now working as a postgraduate student in Tsinghua University, Beijing, China. His area of interest includes microgrid operation.
The neutral point ungrounded system is widely used in China because of its power supply reliability. When an intermittent arc grounding fault occurs, active grounding the fault phase bus can extinguish the arc and suppress the overvoltage. Use of the bus active grounding device adds an extra grounding process with fault characteristics, which can provide data support for subsequent fault line selection. As far as the zero-mode network of the system is concerned, the magnitude and direction of the zero-mode current flowing on each line depends on the location of the fault and changes in the equivalent voltage source. Because of the input of the bus active grounding device, the fault originally located on the line is transferred into the bus, so the electrical characteristics of the two transient processes before and after can be comprehensively used. The zero-mode current of each line is extracted to calculate the line energy, and the energy difference between two transient processes is compared with the threshold value to realize fault line selection. This method uses the current signals of the respective feeders, and it does not require data comparison between feeders. The accuracy and robustness of the proposed method are verified by simulations.
Xiangyu Liu, Master Candidate, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology. His research topics are focused on power system relay protection and distribution network fault location.
Bird-related outage of overhead transmission lines can be divided into bird nesting, bird excrement, and bird short-circuit. The main anti-bird devices include bird-repellent, bird-blocking, and bird-leading. Part of Zhejiang Province is a dense area of bird activity, and some lines are frequently disturbed by bird activities. This article comprehensively analyzes the geographical distribution of bird-related fault risks, typical bird-related failure cases, and related control measures in Zhejiang Power Grid Anatomy. Adhere to the "bionics" bird-proofing path, and in accordance with the concept of "upper and lower guides, coexistence of line birds, human and nature, and harmonious development", innovative use of "dangerous area installation of bird box blocking, safe area setting of bird cages" "Method, combined with high-density inspection and timely processing, can achieve effective control of bird-related faults.
Zhou Luyao, master, graduated from the School of Electrical Engineering, Beijing Jiaotong University in 2016. Currently working at the State Grid Zhejiang Electric Power Co., Ltd. Electric Power Research Institute, mainly engaged in the research of transmission equipment condition evaluation technology, and has been awarded the provincial company-level science and technology award 2 items, published more than 20 academic papers in domestic and foreign journals such as "High Voltage Technology", "China Electric Power", "High Voltage Electrical Apparatus", 5 patent applications, and 3 standards.
The AC-DC hybrid grid is a new form of grid development. The world's largest and highest voltage hybrid grid has been built in China. Unlike the pure AC system, AC/DC hybrid system AC fault characteristics is the result of the superposition of faults in the AC and DC systems. During the fault, the AC and DC systems interact with each other. When a line fault occurs on the AC side, it is easy to cause a commutation failure on the inverter side, which in turn adversely affects the AC system, resulting in a frequency offset of the power frequency fault current. Therefore, the power frequency protection based on Fourier transform has an adaptive problem in the AC/DC hybrid system. When the serious commutation fails, the power will be reversed, and the traditional longitudinal protection may be misplaced. This paper analyzes in detail the commutation failure and power reversal mechanism during AC system failure, the variation of AC system fault characteristics and the applicability of longitudinal protection. On this basis, further explore the impact of fault location and transition resistance on commutation failure, frequency offset and power reversal. Finally, a new protection scheme for power reversal in AC/DC hybrid systems is proposed.
Professor of Xinjiang University's School of Electrical Engineering, mainly engaged in the research of new energy grid connection and AC / DC line protection. I like to share, exchange and learn scientific research experience with outstanding scholars.
To address the comprehensive evaluation of overseas wiring in less developed countries with large urban power grids, the proposed comprehensive evaluation model wiring model based on the optimal combination weighting method. Integrated optimal combination weighting method Delphi method, AHP and Entropy methods, established include reliability, economy, electrical characteristics and adaptability of four evaluation, three typical wiring for each model calculations subjective and objective index weight vector and the optimal combination, to build a comprehensive evaluation model to achieve the planning and design network reconfiguration of overseas cities with large. This design successfully applied to distribution network reconstruction project in Dhaka's Dhanmondi area, improved power supply reliability rate 0.428%, the terminal voltage deviation rate fell 0.106%, 1.754% line loss rate has dropped，economics and adaptability have also increased accordingly.
Ziyi Liu was born in hubei, China, in 1995.She received a bachelor's degree in electrical engineering and automation from China Three Gorges University in 2018.She is pursuing a master's degree in China Three Gorges University, under the tutor of Dr. Tang Bo. Her research interest includes Electromagnetic environment of power transmission and transformation engineering and power transmission line engineering.The subject currently under study is the key technology for the transformation of distribution networks in less developed overseas countries.
Nowadays, the increasing demand for power has overwhelmingly challenged the line design capacity, which has become a severe problem in micro-grids. The dynamic increase in line capacity is an effective solution to this problem. It determines the actual capacity of the line by actual meteorological conditions and real-time monitored line parameters. First, this paper analyzes the influence of the real-time status of various devices on line capacity based on the topology of micro-grid and then demonstrated the feasibility of dynamic capacity increase. Based on the general dynamic capability model, this paper proposes a dynamic capability model based on big data situational awareness technology, which provides the operational basis for dynamic capability improvement. The effect of different factors on dynamic capacity estimated by simulation, from which conclusions are derived. The effect of the model with situation-aware this paper proposes aligns well with the general model. Finally, this paper presents key concepts relevant to real-time situation-aware technology with a graphical interface. The research results lay a foundation for the dynamic growth of micro-grid in actual operation, and have certain reference value for the stable and safe operation of offshore oil platform grid, and will be popularized in the future work.
My name is Guo Min. I am now working at the Fundamental Industry Training Center，Tsinghua University.Participated in the 2018 China International Solar Decathlon and won the runner-up, and participated in the rule-making of the 2020 China International Solar Decathlon.In 2018, I participated in the project of digestive tract disease autonomous detection system.In 2019, we developed the processing course based on Greenplum distributed data system.Participated in many national innovation projects such as offshore oil platform power system research.My current research interests include power system automation, micro-grid, big data systems and deep learning, intelligent hardware and intelligent system, and humanoid robot.
The fault detection device for the equipment in distribution grid station house collects information such as line operation state, line load and voltage through the mobile phone APP and has a real-time detection of line faults to realize on-line monitoring and analysis of distribution lines, which enables the operation and maintenance personnel to know about the line working at any time and provides data support for line perception, early warning and prediction, and auxiliary diagnosis. As the edge facility under the ubiquitous Internet of Things, the fault detection device connects the smart grid and the data from the ubiquitous Internet of Things, which creates an open and innovative data application ecology and provides data services for lean management of the distribution grid. It meets the requirements of "Research on Key Technologies of Sensors and Research and Development of Equipment", one of the five key technical research projects of the State Grid on strengthening the construction of Internet of Things in Power Systems. It is innovative in micro-power wireless communication technology, sensor energy collection technology, weak signal filtering and calculation.
Ba He Ti Bie Ke was born in Urumqi, XinJiang Province in 1990 and obtained his master's degree in Electrical Engineering at Beijing Jiaotong University in 2016. He has worked in State Gird Urumqi Electric Power Supply Company since 2016. His Researched field is the application of universal power internet in distribution network. During the years of working at Urumqi Electric Power Supply Company, he has mainly participated in the world-class distribution of electircal network planning project in Urumqi high-speed railway area and responsibled for the 14th Five-Year Plan of Urumqi Electric Grid. In the past years, He has won the Urumqi Electric Power Supply Company QC Innovation Award and Excellence Award. During the professional training in Shandong, he won the National Network Technology Institute Ourstanding Cadre Award, in addition, published several papers in the core journal.
This paper analysed different constrains of power transmission capacity of large power supply through UHV AC channel, mainly including power angle stability, dynamic stability and thermal stability. The paper also studied the influences of different power supply and grid production timing on the transmission capacity of UHV AC channel. Besides, the paper researched the effects on transmission capacity of UHV AC channel of essential PSS parameter and series compensation. What’s more, the transmission capacities under different PSS parameters and series compensation ratios were calculated. The results showed that the capacity of UHV AC lines could be promoted by optimizing the PSS parameters of units or adding series compensations. The paper also studied the influences of near-area AC lines or main transformers fault on power system stability under different start-up modes. And the corresponding control measures were proposed.
Ping Wu, senior engineer, now is engaged in electrical engineering field related to power system security and stab ility analysis and control, including: AC and DC coordinated control technology, as well as control strategies of UHV AC and DC projects
Line loss and line loss rate are important indexes to reflect the operation of distribution network. Due to the variation of line layout, load characteristics, power supply radius, reactive compensation and so on, the line loss rate is also affected by above various factors. In this paper, several key factors, such as operation mode, reactive power compensation, distributed power supply access and so on, which affect the distribution line loss rate, are studied and verified by simulation. Through real cases simulation, it can be seen that the competence of distribution line is developed and the line loss rate is reduced.
Feng Chen was born in November 1990. He received the B.S. degree in electrical engineering from Zhejiang University, Hangzhou, China, in 2016. His research focus is on FACTs, and energy conservation of power grid.
STATCOM is an important reactive power source in modern power system. The model requirements for electromagnetic transient analysis and electromechanical transient analysis are quite different. The parameter design method in Matlab/Simulink is mature while there is no universal parameter design method in PSD-BPA.
Typical topology and working principles of STATCOM are analysed firstly. The mathematical models of STATCOM in Matlab/Simulink for electromagnetic transient analysis and mathematical models of STATCOM in PSD-BPA electromechanical transient analysis are presented respectively. Both d axis and q axis control loops are presented in the detailed model of Matlab/Simulink. The d axis loop controls the bus voltage / reactive power while q axis loop controls the DC voltage. There are two types of STATCOM models in PSD-BPA. The STATCOM is regarded as a controlled voltage source in one type and the other a controlled current source. Both models contain bus voltage control loop and the DC voltage control loop is ignored since PSD-BPA focus on grid analysis.
Dynamic responses of the two simulation platforms are compared afterwards. Typical parameter design method for detailed model in Matlab/Simulink is presented. Control link functions are analysed and a universal parameter design method for PSD-BPA is present according to the detailed model in Matlab/Simulink.
Ruanming Huang received his bachelor degree from southeast university，China. he is currently serving as a powersystem planning engineer in State Grid Shanghai municipal electric power company.
Reliable lightning protection of 500 kV extra-high voltage substation is essential for its safe and stable operation. In this paper, combined with the design scheme of typical 500 kV substation -- Fengquan substation in west Inner Mongolia power grid, the electromagnetic transient calculation program (EMTP) was used to establish the simulation calculation model of lightning intrusion wave overvoltage of 500 kV extra-high voltage substation. Considering the configuration scheme and parameters of the lightning arrester in the substation, the lightning stroke point, the impulse grounding resistance of the tower and other influence factors, the overvoltage of the electrical equipment in the 500 kV substation was calculated when lightning wave intruded by using the deterministic method. The influence of various factors on the overvoltage was analysed, and the layout scheme of the lightning arrester in the substation was checked. Combined with the altitude of the substation, the lightning impulse insulation level of the substation equipment was checked. Moreover, using the probability and statistics method, the minimum safe operation year of the equipment in the 500 kV Fengquan substation was calculated to be 1455 years, which proved that the safe operation years of the substation equipment can meet the standard requirements. The research results can provide reference for the design of extra-high voltage engineering in west Inner Mongolia power grid.
Lu Tiantian, female, engineer, mainly engaged in research work on overvoltage and insulation coordination, lightning protection and grounding of power systems.
This paper models the typical structures of urban medium voltage distribution network baesd on the power system analysis software CYME，carry out the reliability indexes of each structure under different power supply radius. Then the influencing factors of overhead lines reliability are analyzed in detial, including the power supply radius, the contact switches and line segments，not only illustrates the impact trends, but also quantifies the degree of impacts . Finally, this paper has obtained the recommended typical strutures of urban medium voltage distribution network, which has certain guiding significance for urban medium voltage distribution network planning.
Wenjie Pan, working at State Grid Jiangsu Electric Power CO., LTD. Economic Research Institute, is engaged in distribution network planning research and power transmission engineering design.
The lightning performance calculation model of 500 kV transmission lines—Yongfeng lines Ⅰ, Ⅱ and Ⅲ with high lightning strike trip rate in west Inner Mongolia power grid is established. Considering the factors such as lightning density, topography, and grounding resistance of the tower, the paper calculates the trip rate of back flashover, shielding failure trip rate and total lightning strike trip rate. Based on the actual operation data of 500 kV Yongfeng lines Ⅰ, Ⅱ and Ⅲ in west Inner Mongolia power grid, the reason for lightning trip is researched. Both the calculation results and the operating experience indicate that the main cause of the lightning trip rate of the Yongfeng lines ⅠI, Ⅱ and Ⅲ is shielding failure. On this basis, the method of reducing shielding failure trip rate of the lines is studied, and the targeted differentiated lightning protection measures and transformation scheme are formulated. The research shows that the lightning strike trip rate of 500 kV overhead transmission lines Yongfeng Ⅰ, Ⅱ and Ⅲ can be controlled within 0.14 times / (100 km•a) as long as the appropriate line arresters are installed on the vulnerable towers, vulnerable sections and vulnerable phases.
Lu Tiantian, female, engineer, mainly engaged in research work on overvoltage and insulation coordination, lightning protection and grounding of power systems.
The voltage sag and harmonic detection in distribution network with high proportion of DG is a hot issue[1-3]. The dynamic voltage restorer is an effective method. The detection algorithm is the first and key part. In this paper firstly the voltage sag and harmonic detection problems of distribution network with a large number of DGs integration are discussed. S-transform and improved multi DQ coordinate rotation transform are respectively designed. For a further verify, simulations are carried out in Matlab. The results show that the improved multi DQ coordinate rotation transform method is more flexible for dynamic voltage restorer.
My name is Yitao Guan and I am a postgraduate student of Nanjing Institute of Technology.My Major is electrical engineering.Under the guidance of my tutor,I am very interested in this major and confident to learn professional konwledge well.
The contamination characteristic of high voltage electrical equipment is directly related to its insulation performance. In this paper, the contamination degree and components of two HVDC converter stations in coastal and inland areas are measured, their contamination outdoor insulation characteristics are analyzed in combination with geographical environment, meteorological conditions and the pollution sources in the vicinity. On this basis, a portable salt density measuring device is developed, which can measure the equivalent salt density of insulators in the field, greatly reduce the cost of measurement, improve the detection efficiency, and can be popularized in the field of pollution measurement of outdoor high-voltage electrical equipment.
Wei Li received the B.Sc. degree from the school of Electrical Engineering, Huazhong University of Science and Technology, China, in 1998. He is now engaging in operation and maintenance of substation equipment.
The transmission line passes through the forest, farmland, human gathering place and other complex environment, which makes the transmission lines face the threat of foreign matter invasion. The plastic cloth overlapped on the conductor is easy to cause the transmission line flashover in rainy weather. In order to study the influence of the geometry size and lapping mode of the plastic cloth on its discharge characteristics under different conductivity of rain water, the surface equivalent salt deposit density, no soluble deposit density of the plastic cloth and the resistance under different conductivity of rainwater were measured, and its conductivity was analysed. The discharge characteristics of plastic cloth under different conductivity of rain water, geometry size and lapping mode were studied, and the discharge process was observed by UV imager. It is found that the old plastic cloth has good conductivity. With the increase of the conductivity of rain water and the width of plastic cloth, the flashover voltage of the plastic cloth decreases gradually. In serious cases, the effective value of flashover voltage of the plastic cloth completely overlapped transmission line is 0.38 kV/cm.
Tingyue Jiang was born in Hubei Province, China, in 1996. She received the B.S. degree in electrical engineering from China Three Gorges University, Yichang, China, in 2018. Since this date, she has been a master student in College of Electrical and Electronic Engineering, North China Electric Power University-Baoding Campus, Baoding, China. Her major study is state management of transmission, UHV transformation equipment, insulation system, partial discharge and electric field mapping.
Firstly the working principles, operating characteristics, modeling, control scheme and dynamic characteristics of the unified power flow controller(UPFC) are introduced.Then the application of 220kV UPFC in State grid Shanghai electric power company are studied including the main circuit topology, control scheme and protection configuration. Finally the effects of UPFC on section transmission capacity improvement, voltage stability, regional grid balance are discussed.
Mr.Sun Xin is an electrical Engineer in State Grid Shanghai fengxian Power Supply Company, he has long been dedicated in the research of distribution network and Internet of Energy.
Abstract
This paper mainly studies and analyzes the temperature rise test of oil immersed distribution transformer and dry-type distribution transformer, including the determination of test method and the analysis of test data. In this paper, the temperature rise test of oil immersed distribution transformer adopts the short circuit method, and the temperature rise test of dry-type distribution transformer adopts the simulated load method. Both test methods have the advantages of simple wiring, accurate test data, etc., which are convenient for implementation in manufacturing enterprises. Through the field test, the test data is obtained, and then the resistance value at the time of power failure is calculated. The error between the value and the design value is very small, which shows that the temperature rise values of the two distribution transformers are in line with the temperature rise limits specified in the national standards. This paper also analyzes the uncertainty of the temperature rise test data of two distribution transformers, the test results still do not exceed the national standard temperature rise limit after considering the uncertainty. This indicates that the temperature rise test method adopted in this paper can ensure the accuracy and reliability of the test results.
Key words: distribution transformer; temperature rise test; short circuit method; simulated load method; uncertainty
Postgraduate in Electrical Engineering.
The power supply reliability assessment of microgrid can guide the planning and construction of the system. Fluctuation and power supply supporting effect of distributed generation increase the difficulty and complexity of power supply reliability assessment of the system. In this paper, a power supply reliability assessment method for grid-connected microgrid is proposed. Firstly, evaluation indexes of power supply reliability for microgrid system is introduced. Then, prediction models for distributed generation output and load demand forecasting are established. State sequences of each element in the system are generated by using sequential Monte Carlo method. The power supply reliability result of the whole system can be obtained based on the interruption duration analysis of each load, by using predicted powers of the distributed generations and loads, and remaining capacity of energy storage, which takes load priority into consideration. Finally, a typical case study is carried out by MATLAB simulation in an AC/DC hybrid microgrid, and the effectiveness of the proposed method is verified.
Dr. Geng Niu is now with the China Electric Power Research Institute. His research interests are distributed generation and microgrid technology, fault location and self-healing of smart distribution network.
assistant engineer, master of engineering, mainly engaged in maintenance , electrical test and lightning overvoltage protection.
Merging units, intelligent terminals and other intelligent electronic devices (IED) are currently widely used in smart substations, where optical fiber has taken the place of electric cable in transmitting protection sample values and switch control commands. There are three major technical problems in real-life application. The first one is that the 7-10ms intermediate link process delay induced by merging units and intelligent terminals slows down the protection action. The second is that overheating and hostile working environment can cause increased defect rates of the secondary devices installed in outdoor cabinets. The third is that traditional outdoor cabinets need to be equipped with heat exchangers or air-conditioners, which require a considerable amount of repairs and maintenance work.
This paper analyzes the root causes of the above problems existing in the current field installation IED, and brings forward a design scheme of line protection localization based on new field installation IED and new outdoor cabinets. This paper elaborates on the new IED design scheme. Last but not the least, the paper compares the protection localization scheme based on the new field installation IED and the existing smart substations scheme, and looks into the future application of the new field installation IED in smart substations.
Senior engineer of researcher level, engaged in the research of protection and control platform technology
The UHVDC converter station is equipped with AC filters of different types and parameters, and its overall impedance-frequency characteristics are relatively complex. It can easily cause harmonic amplification by interaction with the grid impedance in some frequency range. For further analysis, the grid background harmonic impedance is needed. The equivalent harmonic analysis circuit for grid background harmonic impedance estimation is given. The 500 kV AC bus of UHVDC converter station is used as the PCC point. The harmonic voltage of AC bus and the harmonic current of converter transformer are taken as observation data, and the data forms a measurement matrix. Then a 500kV grid background harmonic impedance estimation method based on different operating conditions of the converter station is proposed. The measurement matrix is decomposed by singularity value decomposition method, and the grid background harmonic impedance with grid background harmonic voltage is solved by least squares method. Finally, a PSCAD simulation model was built. The simulation results demonstrated the validity and practicality of this method.
Wen-tao Lyu was born in March 1989. He received the B.S. degree in electrical engineering from Zhejiang University, Hangzhou, China, in 2014. His research focus is on FACTS, and power quality of power grid.
The structure of 110kV high-voltage cable terminal is compact and the distribution of electric field is complex. The magnitude and distribution characteristics of electric field on body surface of live line workers are an important basis for formulating the safety protection and operation methods. In aim to attain the distribution of electric field on body surface of live-line workers under different working conditions, Combined with typical 110kV cable outdoor terminal, established human body’s surface electric field analysis model under three working conditions, namely earth potential, flaoting potential and equal potential, and horizontal and vertical entry path. Analysis results show that: The distortion field intensity of head, hands and feet is relatively large. With the distance between workers and cable terminal increasing by 0.1m, voltage decreases by 8% and electric field drops exponentially. When workers accesses to equal-potential in vertical direction, electric field rises about 2.2kV/m for each upward movement of 0.1m. When human body is in different phases, electric field in phase A to phase C gradually increases by 11% per phase. The operation mode and access path provide a reference for cable terminal live working, which has theoretical value and practical significance for ensuring safety of live line maintenance.
Wu Tian(1983-02), Senior engineer, graduated from Wuhan University in June 2012, majoring in High Voltage and Insulation Technology. In 2012, joined the live working laboratory of the Institute of High Voltage Research, China Electric Power Research Institute, and engaged research work on live working, power grid operation and maintenance and external insulation, participate in the development of four industry standards. He joined the School of Electrical and New Energy of three Gorges University in May 2017.
The tower structure and voltage level of 35kV line are between distribution line and transmission line, which makes it difficult for live line operators to choose appropriate electric field protection measures. In order to ensure the safety of live line working on 35kV line, the spatial electric field distribution of 35kV single circuit and double circuit towers and the electric field intensity of live line operators at different working positions are simulated and calculated by finite element method, and the electric field intensity on the surface of live line operators at different working positions is analyzed The distribution characteristics and change rules of electric field on the body surface of the operators, and the corresponding personnel protection requirements are put forward. The calculation results show that the electric field intensity on the surface of the workers' body at the working position is within the limit value when the workers are working on the 35kV single circuit and double circuit line poles according to four typical working conditions, which meets the standard requirements and does not need to wear the live working shielding clothing. The research results provide a technical basis for guiding the safe development of live line operation of 35kV line.
Wang Lei 1981.12 male, Ningjin, Shandong, master's degree, senior engineer, research direction Substation maintenance, live operation management
With the rapid demand of electrical power, distribution networks have been developed broad and complicated. In order to guarantee the reliability of power transmission, medium voltage distribution networks applied resonant earthed to eliminate grounding fault mostly. However, arc suppression coil applied for resonant earthed has poor performance as the growth of capacitative current. In order to eliminate the grounding fault effectively, a method based on controllable voltage source is therefore proposed to improve the full-compensation ability. Controllable voltage source proposed based on IGBT could inject specific phase vector and amplitude of voltage into neutral point, realize self-modulate with the fault condition as well. The verification of the improved scheme for grounding fault full-compensation is supported by PSCAD/EMTP. Results acquired indicated that the method based on controllable voltage source could eliminate the grounding fault fast and effectively.
His major research interest is overvoltage protection.
The working environment of medium voltage networks is complicated and the reliability of fault discrimination is relatively high. However, high impedance ground fault induced by a falling tree or transmission line grounding has relatively insignificant diagnostic efficiency. In order to improve the efficiency of high impendence ground fault identification, an improved identification structure is proposed. Single-phase ground fault experiments were carried out on 10kV test platform, and several fault conditions were taken into consideration. Basing on experimental results acquired, the characteristics of the fault current and the pattern of three-phase voltage were analysed. The structure of high impendence ground fault identification based on support vector machine is established. It is an improvement on high impendence ground fault identification.
His major research interest is overvoltage protection.
With the increase of multi-infeed LCC-HVDC systems (MIDCS’s) capacities, the grid strength of receiving AC systems tends to become weak, which results in static voltage issues. Besides, there have been lots of photovoltaic (PV) converter installed at the receiving AC system of MIDCS. However, the impact of PV converter on the stability of MIDCS has been paid little attention. Therefore, this paper proposes a sensitivity-based method to analyze how the PV converter influences the static voltage stability of the MIDCS. Firstly, we construct the structure-preserving model of MIDCS with a PV converter (located at arbitrary network bus) taken into consideration in quasi-static state. Then, the generalized short-circuit ratio (gSCR) is introduced, which can quantify the grid strength (representing the static voltage stability) of the receiving ac system. Moreover, a sensitivity-based method is proposed to analyze the impact of PV converters on the CgSCR. The theoretical analysis shows that the impact of PV converter on the CgSCR is mainly related with PV converter’s location and control parameter. Finally, we have simulated the effects of different controls parameters and locations of PV converter on the static voltage stability of the receiving AC system in MIDCS and verified the theoretical analysis.
Yuchen Li received the B.E. degree in electrical engineering, in July 2018, from the School of Electrical Engineering, Zhejiang University, Hangzhou, China, where he is currently working toward the MA.Eng degree. His research interests include ac/dc power systems stability analysis and control.
A large-scale multi-infeed direct current (MIDC) system leads to the relatively weak voltage support capability in the receiving AC system. Although it is critical to enhance the strength of AC system for mitigating severe voltage stability issues, it may exacerbate the short-circuit current (SCC) level at the same time. Since the network structure of the MIDC plays a significant role in dealing with the dilemma between grid strength and SCC level, this paper proposes a power network structure optimization method with constraints of static voltage stability and SCC level. First, the generalized short circuit ratio (gSCR) is applied to assess the grid strength of receiving AC system of the MIDC in terms of static voltage stability. Second, the relations between the gSCR and the SCC level are explored. Finally, we propose a solution algorithm based on the sensitivity analysis of SCC, with the goal of minimizing the number of lines to be opened by satisfying the constraints of the gSCR and the SCC level. The proposed method is verified to be effective by simulations that it can both limit the SCC level and ensure the static voltage stability of receiving AC system of the MIDC.
Jiaming Wang received the B. Eng. degree from the School of Electrical Engineering, Shandong University, Jinan, China, in 2018. He is currently working toward the M. Eng. degree from the College of Electrical Engineering, Zhejiang University, Hangzhou, China. His research interests include AC/DC power system stability analysis and control.
Caused by the random fluctuations of wind power, the power network losses become more volatile and changeable. A probabilistic losses analysis method is proposed in this paper considering the output characteristics of the wind power and the fluctuation of load. Multiple samples considering the correlation among multiple wind-power farms are firstly generated with Latin hypercube sampling technique. Using Monte Carlo simulation, we could obtain the corresponding samples of power network losses. The fluctuation distribution and numerical features of power losses can be calculated finally. The validity and rationality of the proposed method is validated on the modified IEEE 30-bus system. The Impact of the wind power output characteristics upon the power losses are also analysed in the end.
An electrical engineer. Work on the economic operation of the power system now.
A new round of electric power system reform for the main body to participate in the market transaction, the chance. Micro power grid as the aggregation of distributed power supply (distributed generation, DG), the effective ways to achieve the DG capacity volatility, stochastic and uncontrolled change, especially under the background of new electric change to microgrid provides a good policy support to participate in market transactions. New electricity to the basic background, this paper studies the operation of the microgrid features and related business, and focuses on analyzing the new electricity island under the change of the microgrid operation characteristic, considering the wind turbines, solar units, fuel cell and energy storage devices and power load of the microgrid model, for the best strategy to achieve internal micro power grid operation structure, the lowest marginal cost, the optimal model in ensuring that the internal network, on the basis of balance between supply and demand, realize the optimal control strategy for micro power grid.
Wang Lei was born in Shanxi, China in 1994. He is a electrical engineer at Inner Mongolia Power Research Institute. He received the master's degree in Power system and automation from North China Electric Power University in 2019. His current research interests are in space charge measurement, electrical insulation and materials, condition monitoring of power apparatus.
It is a multi-objective and multi-constraint, non-linear optimization problem that the maintenance scheduling of transmission equipment in interconnected large power grid needs to consider the guarantee of renewable energy transmission capability and the operational safety of regional power grids. Therefore, a method of maintenance scheduling of transmission equipment based on improved gravitational search algorithm (GSA) is proposed: one of the optimization objectives is to calculate the electric quantity of the abandoned renewable energy. In addition, considering the safety constraints of the operation of the interconnected power grid, the optimization model of the maintenance scheduling is established, and GSA method is used to solve the model. By introducing the idea of simulated annealing (SA) and using the Metropolis criterion to update the particle position according to the probability, the particle degradation in the GSA is reduced, and then the overall convergence and accuracy of the algorithm are improved. The annual maintenance scheduling of the actual power grid is verified as a calculating example.
I have been working in China Electric Power Research Institute for ten years after graduation. I have been engaged in scientific research on power system and the automation. I am now a senior engineer and have published many articles in domestic and foreign journals and in the conferences.
This review starts by providing a horizontal overview of Ubiquitous power Internet of Things(UPIoT). In particular, the review highlights the importance of the communication technology for power transmission and distribution system. Wireless access technology is a key technology at UPIoT network layer. By introducing low power wide area network(LPWAN) technologies combined with traditional wireless communication technologies, UPIoT are able to achieve exquisite energy management by reliable communications and extensive connections. In this review, the wireless access technologies applicable to UPIoT are divided into two categories: long-range wireless communication technology, which is suitable for communication scenarios of power equipment such as mass “transmit-transmit-transform-deploy-use” terminals, “factory-station-line-transform-house” distributed sensing terminals and short-range wireless communication technology, which is suitable for short-distance intelligent interactive terminal communication services. Finally, novel communication technologies and the application of 5G in power transmission and distribution scenarios are also discussed.
ZhangXi is a graduate student in the School of Automation Science and Electrical Engineering, Beihang University, China. She is particularly interested in power transmission, Internet of Things and cloud manufacturing. Her research topic is the Key Technology Research of Ubiquitous Power Internet of Things Data Acquisition based on Cloud Block chain. She participates in the State Grid Science and Technology Project: Ultra-High-Voltage Direct Current Power Lines Three-Dimensional Space Synthetic Electric Field Measurement Technology Research, and National Key Research and Development Program of China: Manufacturing Mega Data and Model-Driven Industrial APP Construction Technology.
Transmission corridor, which is the key link of the transmission network, is composed of some high voltage and capacity transmission lines. With the increase of outside destroy risk points and transmission lines, the traditional prevention work of outside destroy of transmission line needs more human and material resources. This paper analyzed outside destroy failures of Zhejiang grid. Research on panoramic monitoring of transmission line developed by state grid Zhejiang power company was introduced.
Dr. Yuan Gao. Working at shanghai university of electric power. Dr. Gao mainly focus on oil flow electrification in oil-paper insulation transformer, tphoon disasters of power transmission system, online monitoring of transmission lines and lightning protection of power transmission system.