bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Loss and Temperature Increases in Hollow Oil-immersed Reactors
Authors: Xiao Shijie , Yu Peixiang , Chen Zhenxing , Zheng Hai , Chen Gang , Li Shiqiang , Li Hanping
Published: July 2019

Oil-immersed hollow reactors have been applied to high-voltage frequency-modulated resonant power supplies due to their favorable linearity and high insulation strength. A high-quality reactor is the key component of a high-voltage test system. The characteristics of loss and temperature-rise characteristics are the core factors affecting the quality factor of the reactor. In this paper, a finite-element numerical simulation model was established based on a large capacity series resonance test system for a 500-kV submarine cable in China. The eddy current loss, AC resistance loss, and circulating current loss of the oil-immersed air-core reactor were calculated. With these as a foundation, the flow and temperature field distribution characteristics were obtained for an oil-immersed hollow reactor through the coupling of magnetic heat and flow field. Finally, the temperature distribution characteristics of the reactor were compared with the dates obtained from the release testing, and the reliability of the calculation model was verified.
Application of PEEC Model in Calculation of Transformer High Frequency Voltage
Authors: Han Mingming , Chen Bo , Zhu Wenbing , Gu Chao , Yi Feng
Published: July 2019

Overvoltage will occur on transformer windings when high frequency waves such as lightning strike and Very fast transient overvoltage(VFTO) intrude into transformer windings. The model and parameters is the basis of calculating transient overvoltage in transformer windings. In this paper, partial element equivalent circuit (PEEC) is used to calculate High Frequency Voltage on transformer windings. the inner grid of conductor through which conductive current passes and the surface grid of conductor with charge distribution is used to transform into the inductance unit and capacitance unit of PEEC respectively. The mutual capacitance between different windings is solved by PEEC. The change regulation of resistance coefficient of transformer windings under different frequency waveforms is analyzed, and the internal voltage of transformer under different frequency applied voltage is solved. The results show that the self-inductance of winding decreases slightly with the increase of applied voltage frequency, and basically remains unchanged in high frequency band. With the increase of frequency, the voltage waveform on winding turns decreases rapidly.
Research on Low Voltage Ride through Strategy for Power Electronic Transformer
Authors: Kong Xiangping , Li Peng , Han Jiexiang , Zhang Zhe , Yin Xianggen
Published: July 2019

In view of the operating characteristics for voltage sags of AC side of the power electronic transformer(PET), a low-voltage ride through(LVRT) strategy adapted to bidirectional power exchange of PET is proposed for the purposes of maintaining the system stability, assisting the system voltage recovery and protecting PET safety. During the asymmetric voltage sag, the negative sequence current of PET is eliminated to ensure the symmetry of the injected current. According to the degree of positive sequence voltage sag, the reactive current injection is provided to assist in voltage recovery. According to the PET active power condition before the voltage sag, the level and direction of which are maintained as far as possible without exceeding the limit, for which the disturbance to the AC and DC grids is reduced. Finally, the effectiveness of the proposed LVRT strategy is verified by simulation model.
Optimal Coordination Voltage Control of Hybrid AC/DC Grids Considering Control of HVDC System
Authors: Yang Chao , Shi Fangfang , Sun Mengmeng , Wang Liang , Zhang Bing , Liu Meng , Wang Xin
Published: July 2019

With the wide application of UHVDC in long-distance and large-capacity power transmission, the current power grid has developed into a complex AC-DC deep coupling system, which poses a serious challenge to the voltage safety control of the system. Based on the voltage sensitivity of AC/DC system, this paper presents a voltage optimization control method for integrated coordination of AC/DC system control variables. In this control method, a linear constrained quadratic optimization model with minimum control cost is constructed to coordinate the control variables of AC/DC system and correct the voltage amplitude deviation. The potential of UHVDC system to participate in voltage control is studied by optimizing the control quantity of rectifier side and inverter side converters. The simulation results of AC/DC hybrid system show that the proposed optimal control method can effectively coordinate the control quantity of AC/DC system and ensure the voltage operation in a safe range.
Transformer Fault Prediction Method Based on Multiple Linear Regression
Authors: Jiafeng Qin , Chao Zhou , Longlong Li , Demeng Bai , Wenjie Zheng
Published: July 2019

This paper mainly analyzes the transformer fault evolution rule. Meanwhile it analyzes the correlation relation between transmission and transformation equipment fault characteristic parameter and the fault. This paper establishes the fault characteristic parameter multi-factor forecast model and the equipment fault diagnosis model, which realizes the transformer fault occurrence probability, the fault type and the fault position real-time accurate forecast. It includes data acquisition and preprocessing, multi-factor prediction of fault characteristic parameters, correlation analysis of characteristic parameters and fault types, failure probability of various faults, equipment failure probability and fault diagnosis. In this paper, a transformer characteristic parameter prediction model based on environment and other factors is proposed. The example analysis of transformer characteristic parameter multi-factor prediction model based on multiple linear regression (MRL) shows that the multi-factor prediction model can effectively consider the influence of external factors on the variation of characteristic parameter, and the prediction accuracy is higher.
Adaptive Droop Control for DC Voltage Deviation and Power Sharing in Multi-terminal DC(MTDC) Grids
Authors: Teng H D , Ning L H , Yin Y J , Gao L , Liu N M , Xie C X
Published: July 2019

Voltage source converter multi-terminal DC system(VSC-MTDC) have been used in many applications due to their many advantages. With conventional droop control, the voltage and power of the stable point are on a straight line with a specific slope. When subjected to a power disturbance, the voltage quality may be deteriorated or the power distribution effect of the converter station may be deteriorated. In this paper, a new adaptive control strategy is proposed for VSC-MTDC. The control system focuses on voltage quality at low loads and power distribution at high loads. It not only ensures voltage quality but also meets power distribution requirements. Simulation results are provided to verify the validity and effectiveness of the proposed method.
A Consensus-based Nonlinear and Lipchitz-continuous Distributed Cooperative Secondary Control Method for Islanded AC Microgrids
Authors: Meng Xiaoxiao , Zhou Niancheng , Wang Qianggang
Published: July 2019

In this paper, a consensus-based, nonlinear, and Lipchitz-continuous distributed secondary control (DSC) method is proposed to coordinate all the distributed generators (DGs) in an islanded AC microgrids (MGs). This proposed DSC strategy can not only guarantee the restoration control for frequency and voltage, but also realize an accurate active power sharing control for the whole microgrid system. Through introducing a nonlinear, Lipchitz-continuous dynamic from Beta Probability Distribution Function (Beta PDF), the convergence speed of DSC is accelerated, the finite-time convergence of DSC is ensured, and the transient overshoot of DSC is diminished comparing with traditional DSC. Moreover, the common chattering phenomenon in non-Lipchitz DSC scheme is eliminated. The stability and performance of the proposed DSC are also analysed in this paper. An islanded AC microgrid test system with four inverter-based DGs is built in MATLAB/SIMULINK to further validate the effeteness of the proposed DSC strategy.
Study on Low Frequency Oscillation of Wind-solar Hybrid Generation System
Authors: He P , Wu X X , Chen J , Li C S , Ji Y Q
Published: July 2019

Wind-solar hybrid generation system can significantly improve the utilization efficiency of intermittent renewable energy as it can make full use of the complementarity of wind-solar. Meanwhile, it will affect the low frequency characteristics of power system. Effect of different wind-solar accommodation conditions on low frequency oscillation characteristics of power system are analyzed based on IEEE 2-area 4-unit system. Eigenvalue analysis and dynamic time-domain simulation are adopted to figure out the influence, including different factors such as separate integration, grid-connected integration points and hybrid capacity ratios of wind-solar.
Research on the Under-voltage Optimal Control Method of Analytical Sensitivity for Power Simulation Training
Authors: Xu Zhengqing , Yan Faqi , Zhou Chaofang , Xiao Yanwei , Sun Shu-qin , Cao Hua-song , Liu Yu-jie
Published: July 2019

As China increasingly interconnecting power system, more and more factors are interfering with the stable operation of the power system. Due to the lack of system reactive power and the overload, resulting in the increasingly problem of low voltage amplitude. Voltage is a measure of whether the power system operation is basically normal index, the voltage level of the power network determines whether the whole power system is stable or not. The dispatcher and operator need to answer any specific challenges to solve the under-voltage in training simulator. In this paper, based on the analytical sensitivity method, the basic principle of the low voltage problem is solved by the method of load shedding and reactive power compensation. Then the low voltage control method is optimized from two aspects of the load shedding load and reactive power compensation. The reactive power compensation with high sensitivity is presented. If the voltage of the compensation is not returned to the allowable range of the state, cutting the load operation according to the magnitude of the load-shedding sensitivity. Using power system simulation software to build a low voltage model of the IEEE-39 classic power system for the sensitivity index and the low voltage optimization control methods are analyzed and verified.
Research on Virtual Synchronous Generator Control for Vehicle-to-Grid System
Authors: Xinchen Zhao , Hui Wang , Ke Wang
Published: July 2019

This paper investigates the concept of Virtual Synchronous Generator (VSG) and analyses the working principle of common VSG control technology. With the promotion of Vehicle-to-Grid(V2G) technology, large-scale power electronics devices will be connected to the grid. Consequently, the stability of the grid will be influenced by the lack of mechanical inertia and system damping within these power electronic devices. The extant normal control methods are difficult to cope with this issue. Accordingly, a VSG control technology is proposed by this study, which can be applied to V2G system. Moreover, the mathematical analysis of this control method is also suggested in this research. This control method provides mechanical inertia and system damping, which is similar to synchronous generators. It also can achieve the accurate control of power. The original P/Q-U-I three-loop control is simplified to P/Q-I dual-loop control in the condition of not losing the inertia of the converter. Ultimately, the simulation examines the accuracy and effectiveness of the control method.
Optimization Strategy for Improving Power Supply Capacity in Distribution Networks with Electric Vehicle Integration
Authors: Ning Yonglong , Zou Meng , Luo Rongmao , Zhang Xiaolei , Wang Yang
Published: July 2019

In order to alleviate the heavy air pollution problem in China in recent years, power energy alternative loads, such as electric vehicles, are widely integrated into distribution networks, which has a significant impact on power supply capability of distribution networks. In this paper, considering the randomness of electric vehicles, probabilistic multiple scenarios generation method is proposed based on Latin hypercube sampling method, Cholesky decomposition and synchronous back-off reduction, realizing the quick scenario generation with the balance of scenario number and precision. Based on probabilistic multi-scene, taking the power supply ability of distribution network as the main objective, a robust operation optimization model of distribution network containing electric vehicles is established in order to optimize the opening and closing status of the switches. Ant colony algorithm based on the Pareto optimal is adopted to solve the model. A modified IEEE 33 node system is used to verify the effectiveness of the model and algorithm, and simulation results show that the proposed method can effectively promote the power supply ability of distribution networks, and can greatly improve the computational efficiency of the model in the case that lots of uncertain parameters exist due to large-scale integration of electric vehicles.
Research on AC/DC Power Flow Optimization by Using Interior Point Method
Authors: Sun Shuqin , Li Yongbin , Xu Zhengqing , Li Mingjia , Wang Can
Published: July 2019

At present, China’s power system is developing in the direction of AC-DC parallel connection. AC-DC hybrid transmission has become the inevitable pattern of China’s future power grid. In the operation of AC/DC hybrid system, the optimization of multiple indexes is often considered. One of the economic problems of system operation is how to minimize the operation cost of the system. This requires the optimal solution of a system of nonlinear equations with constraints. Among the existing algorithms, the interior point method has excellent convergence performance and has been widely used in power system. In this paper, the basic principle of interior point method is introduced, and the interior point method is used to optimize the AC and DC power flow obtained. With the network operation cost as the objective optimization index. The Matlab software is used for programming and simulation calculation. On the basis of verifying the effectiveness of the algorithm, the algorithm is transplanted into the large network for calculation and analysis, and the adaptability of the test algorithm.
Optimizing Capacity Configuration of Photovoltaic and Battery Energy Storage Systems in EV Charging Station based on Time-of-Use Pricing
Authors: Hai Xiaotao , Yin Lu , Jia Zhuo , Yu Qiang , Wang Yu , Yao Defei
Published: July 2019

In order to improve the utilization efficiency of photovoltaic system (PV system) and battery energy storage system (BESS) in photovoltaic and battery energy storage integrated electric vehicle (EV) charging stations, the capacity of PV system and BESS need to be allocated reasonably. In this paper, the maximization of the net annual financial value is used as the objective function of photovoltaic and battery energy storage integrated EV charging station in its whole life cycle. The control strategy of BESS is proposed based on time-of-use pricing. And then the optimization configuration model of PV system and BESS capacity is built. The economic efficiency of EV charging stations is compared and analyzed with actual test system when PV system and BESS configurating. The results indicate that the income and investment payback period of charging stations can be significantly improved through the reasonable configuration of PV system and BESS.
A New Distribution Network Structure for Maximizing the Allowable Penetration of Distributed Energy Resource
Authors: Zhao S S , Song X H , Li Y J , Gao F , Zhang Y , Li J F , Jia Z Y
Published: July 2019

The traditional network structure cannot be suitable for the connection of large-scale distributed energy resources, thus the high penetration of distributed energy resource (DER) will have destructive effects on the security and reliability of the traditional distribution network. The paper proposes a new distribution network structure to increase the maximum allowable penetration of DER. Firstly, the model and method of the new distribution network structure are presented. Secondly, the theory basis of increasing the DER penetration by the new network structure is proved. Finally, the proposed model and method are applied to the typical test case. And the simulation results show that compared with the traditional structure, the new distribution network structure can not only increase the maximum penetration of distributed energy resource greatly, but also realize the high energy efficiency, reliability and sustainability. Therefore, the issue of future distribution network security with high penetration of distributed energy resource can be well solved by the new distribution network structure proposed in the paper.
Multi-period Robust Dispatch of Active Distribution Network Based on Scene Analysis Method
Authors: Hu W , Deng Z L , Lu X , Y W , Zhu X , Xu X H
Published: July 2019

With the large-scale access of intermittent renewable energy, the active distribution networks (ADN) is facing great challenges on achieving full consumption and efficient use of intermittent renewable energy on the premise of ensuring safe operation. To resolve these issues, a novel multi-period robust dispatch strategy for ADN based on scene analysis method is proposed in this paper. Then, the second-order cone relaxation (SOCR) is used to transform the original model into a mixed integer second-order cone programming (SOCP), which gains as much improvement as possible in computational performance at the expense of as few losses as possible in accuracy. Finally, numerical test on the modified IEEE 33-bus test system demonstrates that on the premise of realizing the maximum utilization of DG, the proposed strategy can also achieve the purposes of energy-saving, loss reduction and improvement in voltage level.
A Supply and Demand Matching Algorithm for Industry-Park-Level Power System Considering Multiple Timeframe Outputs of Distributed Generators
Authors: Zhang J , Han X Y , Zhang W , Gao J , Zhang Q , Jin X L , Wang Z
Published: July 2019

In this paper, a supply and demand matching algorithm for industry park level energy systems is proposed. The algorithm can provide the configuration scheme of distributed generators installed capacity in line with the given load demand. Comprehensively considering the output characteristics of distributed sources such as wind and photovoltaic generators in different timeframes, the outputs of distributed generators are classified into several typical modes, and the installed capacity of distributed generator is matched in line with the representative output mode and the load demand curve so as to realize the balance of energy supply and demand in the industry park. The energy storage device is used to balance the energy due to the asynchronism of the distributed generator output and the load demand. The capacity requirements of the battery under various installed capacities of distributed generators are provided. The proposed algorithm is programmed in MATLAB and verified by the actual data of an industry park in northeast China. The results show that the proposed algorithm can comprehensively consider the output characteristics of distributed generator in different time ranges, and provide reasonable matching schemes of energy supply.
Multi-objective sequential CHP Placement Based on Flexible Demand in Heat and Electricity Integrated Energy System
Authors: Chen Yuqing , Yang Shihai , Ji Feng , Cao Xiaodong , Li Bo , Zhou Xiaoming
Published: July 2019

In order to improve the overall energy efficiency, one of the important trends in the field of energy is the construction of integrated energy systems. In the energy Internet, the comprehensive demand response makes use of the coupling and complementary relationship between different forms of energy, such as electricity and heat, and carries out the coordinated optimization of energy conversion equipment on the demand side to stimulate the flexibility of the comprehensive energy network, which is conducive to improving energy utilization efficiency and reducing energy supply and consumption cost. In this paper, considering the comprehensive demand side response of electricity and heat, an optimal configuration scheme of combined heat and power (CHP) unit is proposed. The scheme takes voltage amplitude, integrated network loss and economic cost as the comprehensive optimization objective. In order to effectively solve the above problems, this paper applies the sequence configuration strategy, adopts the direct power-thermal power flow method, weighted summation method and improved genetic algorithm to solve the above problems. Finally, the simulation of real medium voltage distribution network in Australia was carried out by MATLAB programming, which verified the rationality and superiority of the model.
Corrosion Mechanism and Corrosion State Detection Method of the Grounding Grid
Authors: Huang H , Liu Y C , Xing Y , Wu J R , Mao X Y , Wu Y Y , Peng M F
Published: July 2019

Corrosion of grounding grids can affect the safe and reliable operation of power systems. In view of the corrosion problem of the grounding grid, this paper introduces the corrosion mechanism, which is chemical corrosion and electrochemical corrosion respectively. Then, three common grounding grid corrosion detection methods, such as electric network analysis method, electromagnetic field detection method and electrochemical method, are introduced. On this basis, the advantages and disadvantages of three methods are compared. Further prospects for the corrosion detection technology of the grounding grid are pointed out.
Simulation Study on Pole-to-Pole Short Circuit Faults of the Hybrid Multi-terminal DC Transmission System
Authors: Zheng Mengyuan , Kang Xiaoning , Liu Le , Li Xiaoyu
Published: July 2019

The hybrid multi-terminal direct current (MTDC) system, with the economic superiority of LCCs and technical flexibility of VSCs, is one of the development directions of future DC transmission technology. This paper introduces the development of Hybrid-MTDC transmission projects as well as the related publications especially on fault control strategies. A ring hybrid three-terminal DC transmission system was built on PSCAD/EMTDC to simulate pole-to-pole short-circuit faults at different locations. The fault development process and fault characteristics on DC lines are analysed and summarized, which aims at providing the theoretical basis for the protection principles of hybrid MTDC systems.
Maintenance Scheduling of Power Equipment Considering Opportunistic Maintenance Strategy
Authors: Xu Bo , Zhang Yumin , Sun Kongming
Published: July 2019

This paper investigates the impact of opportunistic maintenance strategy on power equipment maintenance scheduling under economic dependence. The model focuses on power equipment with two types of failures: random failure and deterioration failure. Unlike previous research which didn’t consider opportunistic maintenance between different failures modes, opportunistic maintenance strategy is proposed in this paper. In the opportunistic maintenance strategy, whenever random failure occurs, decision has to be made on whether deterioration failure is preventively maintained based on the degree of equipment deterioration and economic dependence. Firstly, Markov process is used to describe equipment state-space diagram. And then, in order to determine the optimal inspection rate, preventive maintenance threshold and opportunistic maintenance threshold of power equipment, the analytical expressions of inspection cost, maintenance cost, repair cost and outage cost are quantified. Finally, the total cost is minimized to get the optimal maintenance strategy. Case studies demonstrate the feasibility of the proposed model.
A New Location Method of Faulty Segment for Hybrid Transmission Lines Based on Transient Travelling Wave Analysis
Authors: Tang Xu-ming , Guo Ning-ming , Xia Wei , Liu Tie , Zhao Cai-ping
Published: July 2019

The paper proposes a new location method of faulty segment for hybrid transmission lines combined with overhead line and cable. Conventional location method of faulty segment identify faulty segment through position calculation of fault point. However, affected by error, the fault at cable-overhead line joint is hard to be identified. In this approach, faulty segment is identified through characteristics comparison of transient travelling wave under different condition. Compared with situation that fault occurs on overhead line, if fault occurs in cable, there is an additional impedance discontinuity in cable. Thus, the amplitude and wave of various reflected wave will change significantly. The proposed method extracts various reflected waves based on time windows and polarity. It makes use of the relative amplitude and time difference between first travelling wave and secondary reflected wave of cable-overhead line joint as criterion of faulty segment location. To verify its effectiveness, fault simulations based on EMTDC are performed; the simulation results reveal that the proposed method can correctly identify the faulty segment for hybrid transmission lines.
High Voltage Circuit Breaker Fault Diagnosis Based on Reasoning chain and Bayes
Authors: Sun Mengxuan , Chen Qing , Huang Wudi , Zhang Xiaotong , Gao Wangyuan
Published: July 2019

In order to find the reason of the high voltage circuit breaker rejection quickly, an fault diagnosis method based on reasoning chain and Bayesian network (BN) is presented in the paper. Firstly, the concept of event set is introduced. A fault symptom set is constructed based on the measured circuit breaker characteristic parameters and warning signals. And the direct cause of circuit breaker failure, such as a part of the circuit breaker components or mechanism failure constitute the fault cause set. After that, when the high voltage circuit breaker fails, a subset of fault symptoms and fault causes is obtained according to the information. Then an reasoning chain is constructed according to the causal relationship between the two. Finally, a corresponding Bayesian network model for reasoning chain is built. The probability of fault causes is obtained by Bayesian backward reasoning, so as to realize the rapid analysis of circuit breaker faults. And the effectiveness of the method is verified by the result of practical fault diagnosis examples.
Novel Switched Reluctance Machines for Domestic Appliances
Authors: Lei Y K , Tang Q , Li T , Wang Y L , Xu W T , Deng Y Y
Published: July 2019

Switched reluctance motors (SRM) are the core components of household appliances, which directly affect the performance and quality of household appliances. We have studied the application of switched reluctance motors in the home appliance industry. The 12/8-pole three-phase switched reluctance motor with a new rotor structure was proposed for the performance of SRM and the performance is simulated by MATLAB tools. Besides, the control principle and the operating equations of the switched reluctance motor are also introduced and deduced in detail. For the further work, although the 12/8 pole switched reluctance motor can effectively reduce the torque ripple, it cannot be completely eliminated. Therefore, the next step should continue to explore ways to reduce torque ripple.
Operation Situation Assessment of Intelligent Distribution Station Based on Internet of Things
Authors: Hui Zhao
Published: July 2019

In order to solve the problem of online monitoring and early warning evaluation of intelligent distribution station, an operation situation assessment of intelligent distribution station based on internet of things is proposed. A multi-source data information matrix is established for the distribution station, and describes the temperature information, humidity information, water intrusion information, smoke information, switch telemetry information, and switch remote control information of the intelligent distribution station within a period of time before the current time. The distribution station multi-source information matrix is quantitatively evaluated through the distribution station multi-source evaluation matrix. Then, the distribution station multi-source evaluation matrix is quantitatively integrated for each column to generate a distribution station multi-source single evaluation matrix. Finally, based on the weighted average method, the distribution station multi-source single evaluation matrix is integrated to generate the distribution station operation situation evaluation index to describe the overall operation situation assessment of intelligent distribution station. The feasibility of the proposed method is verified by the example analysis, which can meet the actual needs of the field project.
An Intelligent Operation and Maintenance System for Power Consumption Based on Deep Learning
Authors: Huang Zengrui , Mao Wei , Chen Ming , Wu Qiang , Xiong Boyue , Xu Wei
Published: July 2019

With the advent of the era of power big data, power companies can easily access more and more user power data, but they are not making full use of such massive datasets to reflect their value. Due to the huge amount of data collected by the power system, the total amount of abnormal data collected cannot be ignored. These abnormal data cause great interference to subsequent data analysis and maintenance; It’s also important to find how to identify user’s abnormal behaviour based on the power dataset. In this paper, a smart operation and maintenance system based on deep learning is proposed. Based on the composite mathematical statistics method, the data is efficiently reviewed and cleaned. The isolated forest algorithm is used to quickly identify the users with abnormal power consumption and GAN is used to help evaluate this model. This system can help power companies efficiently complete data review and anomaly identification, and can integrate data information from multiple dimensions to guide the actual maintenance and verification.
Research on Power Trading Platform Based on Big Data and Artificial Intelligence Technology
Authors: Yuan Mingzhu , Fang Yin , Lv Jingwei , Zheng Shiqiang , Zhou Zhiyi
Published: July 2019

We achieve an integration of the power trading business with new technologies by rationalizing the convergence path of new technologies and transaction services. To realize the personalized customization of electricity market information services and form automated and flexible expansion capabilities, we build a new architecture of cloud-based power trading platform which establishes and applies power market big data resources, improving platform capacity and business application level. The architecture built in the article achieves the decentralization, real-time processing, high concurrency, high availability, easy maintenance, and convenience and efficiency of the power trading platform.
Research on Neural Network MPPT Algorithm Based on DE and Dichotomy
Authors: Li Xiaojiao , Qi Xuanxuan
Published: July 2019

Aiming at the shortcomings of traditional MPPT method, such as slow tracking speed and oscillation at maximum power point, this paper combines neural network with dichotomy to propose a new maximum power point tracking method for photovoltaic power generation system. And the traditional neural network uses the gradient descent method to solve the problem that the parameters are easy to enter the local optimal solution. In this paper, the improved differential evolution method is used to solve the global optimal solution. The neural network is used to track the vicinity of the maximum power point, and then the dichotomy is used to further approach the maximum power point. The simulation results show that compared with the traditional MPPT method, BP neural network and dichotomy can track the maximum power point faster, avoid the oscillation phenomenon, and have faster tracking speed and higher tracking accuracy.
Research on Simulation Training System of Immersive Substation Based on Virtual Reality
Authors: Liao Xiaohui , Wang Hao , Niu Jinliang , Xiao Jingbo , Liu Chuan
Published: July 2019

Virtual reality technology has been widely used by constructing a virtual space to simulate and restore the real world. The system uses 3ds MAX and Unity3D software to establish a 500kV substation virtual simulation system. The system completely establishes the 3D models of primary and secondary equipment of 500kV substations, and truly restores the overall layout of the substations. At the same time, the Unity3D engine, VR technology and interactive equipment are used at the same time to make this system able to provide trainees with an immersive training experience, which is more realistic than the application over the same period. The system completes the realization of substation training, station roaming and fault simulation functions, including substation equipment technical parameter display and synchronous voice introduction, interface design, basic operation, and fault phenomenon simulation; the infrastructure of the system is developed well and has strong expandability, which lays a foundation for subsequent function development. This system satisfies the substation training needs and can be used for related staff training of substations and to help students in electrical major to gain cognitive learning.
Model and Simulation of Micro Grid Based on Micro Gas Turbine
Authors: Wang J H , Li Z , Zheng T
Published: July 2019

Site Microturbine Generation (MTG) is a distributed Generation technology with wide application prospect in micro grid. This paper introduces the single-axis micro-gas turbine power generation system in detail and studies its operation and control in micro-grid. In this paper, PSCAD/EMTDC simulation software is used to simulate the load tracking ability of the micro-turbine power generation system under the island operation mode, and the ability of the micro-turbine power generation system to stabilize the voltage and frequency under the two modes of island and grid connection. The simulation results verify the correctness of the micro gas turbine model and its flexible adjustment control mode according to the needs of micro grid operation, which has good operation characteristics.
Optimal Control Technology of Electric Power Load Distribution of Submarine Cable Salvage Robot
Authors: Yubing Duan , Xiaoli Hu , Chao Gu , Xiaobin Sun , Jinxia Yao , Bo Yang , Hao Zhang
Published: July 2019

The submarine cable salvage robot needs energy storage device as power supply or backup power supply when working underwater. The optimal control strategy of load distribution can realize the reasonable distribution of electric load among multiple energy storage devices according to the different residual capacity of energy storage devices, thus improving the energy utilization efficiency of energy storage devices and prolonging the operation time of salvage robots.
Construction of the Indicator System Applied to Evaluate Basic Capabilities of Smart Meter Enterprises on NQI
Authors: jingxing Liao , Lei Feng , Juxiu Huang
Published: July 2019

In order to quantitatively evaluate the basic capabilities of smart meter enterprises on National Quality Infrastructure (NQI) and continuously improve the quality level of smart meter enterprises, this paper, profited from China’s NQI capability index system and the Delphi method, with representiveness of indicators as the starting point, and based on repeated screening and expert demonstration, chooses the most representative indicators devised for NQI factors such as measurement, standardization, certification & accreditation, inspection & testing and quality management in the production of smart meters, and constructs an indicator system applied to evaluate the basic capabilities of smart meter enterprises on NQI, which includes 5 first-level indicators, 8 second-level indicators and 30 basic indicators. With construction of this system, we can quantitatively evaluate the basic quality and technology capabilities of smart meter manufacturers and continuously improve deficiencies of enterprises on their NQI. And, the State Grid can also apply this system as a technical specification to evaluate the quality level of smart meter enterprises.
Research on Electromagnetic Radiation Model of Corona Discharge with UHV AC Transmission Lines
Authors: Li Chaoqun , Xu Song , Xia Zhuqing , Yang Xin , Wu Xixiu
Published: July 2019

The corona discharge pulse current has double exponential distribution characteristics. On this basis, the electromagnetic radiation model of corona discharge is established by using the theory of electric dipole. The corona discharge characteristics are analysed and compared with the measured results of 1000kV UHV ac transmission line. The results show that the electromagnetic field strength increases first and then decreases with time, and at the same time, the electromagnetic field strength decreases exponentially with distance. The simulated and predicted corona discharge radiation characteristics have the same variation law as the measured data, which verifies the correctness of the model.
FEM Analysis of Iron Core Losses in Magnetically Controlled Shunt Reactor with Distributed Magnetic Valves
Authors: Tong Li , Hu Caifei , Li Xiaohui , Fan Xueliang , He Liqun
Published: July 2019

In this paper, the MCR with distributed magnetic valves is proposed. The magnetic valve is equally distributed in iron core, which is piled up by silicon-steel sheets and epoxy sheets. Field-circuit coupled simulation model is established in ANSYS software. The wave forms of electrical state variables, magnetic flux density distribution and iron core losses are acquired. The comparison with the MCRs with a single-stage magnetic valves and multiple-stage magnetic valves demonstrates the advantage of proposed magnetic valve structure.
A Design of Interior Permanent Magnet Synchronous Motor for Electric Vehicles
Authors: Zhang Jinlong , Yin Dejun
Published: July 2019

Fractional slot concentrated winding interior permanent magnet synchronous motor (PMSM) has the advantages of high torque density, high efficiency and simple manufacture, which has been widely used in electric vehicles. In this paper, a fractional slot concentrated winding interior permanent magnet synchronous motor (PMSM) with “▽” shape rotor is proposed. This paper focuses on how to reduce the torque ripple of the motor. The permanent magnet angle and eccentric length are optimized to maximize the fundamental air-gap flux density and minimize its torque ripple. The cogging torque, torque ripple, iron loss and efficiency of the motor are analyzed. Finally, the finite element results verify the effectiveness of the optimization.
Research on Current Transfer Characteristics of Hybrid Circuit Breaker in Low Voltage DC Micro-grid
Authors: Guanying Zhang , Fei Gao
Published: July 2019

The analysis of current transfer characteristics of hybrid DC circuit breakers is of great significance for improving their breaking capacity and implementing control strategies. This paper analyzes the principle of hybrid DC circuit breakers. The hybrid circuit breaker simulation model is built based on the Mayr arc model in Matlab/Simulink using IGBT, RCD snubber circuit and arrester model. The current simulation waveforms under different external circuit parameters and transfer branch parameters with a voltage of 400V and breaking fault current less than 200A are mainly studied. Through the analysis of the current transfer characteristics, a series of theoretically supported breaking characteristics are obtained, which provide a reasonable and effective reference for the fast and reliable breaking of DC micro-grid hybrid circuit breaker.
Analysis of Unbalanced and Inadequate Development of Power Grids
Authors: Zhang Yue , Wang Chunsheng , Zhang Yan , Zhang Jun , Han Xinyang , Jin Xiaoling , Chen Mingfeng
Published: July 2019

The principal contradiction facing Chinese society has evolved. What we now face is the contradiction between unbalanced and inadequate development and the people’s ever-growing needs for a better life. As power grids play a significant role in energy resource distribution and utilization, the quality of power grid development is the foundation of healthy social and economic development of China. This paper analyses the unbalanced and inadequate development of power grids. Firstly, current situation and problems of power grid development are analysed. Secondly, an evaluation system of unbalanced and inadequate development of power grids is built to quantitatively assess the development of power grids. The unbalanced development index system is composed of secondary indicators of unbalanced urban and rural grid development, unbalanced regional grid development and unbalanced load development. The inadequate development index system is divided into scale indicators, quality indicators, automation indicators and management indicators. Each secondary indicator is then further detailed into tertiary indicators. Then, a case study of provincial power grid is applied to prove the effectiveness of the proposed index system. Study results highlight some problems, for example, unbalanced transmission and distribution grid development, unbalanced urban and rural grid development, unbalanced regional grid development, inadequate distribution grid development, inadequate automatization etc. Lastly, future improvements and measures are pointed out.
A Mutual Inductance Measurement Method for the Wireless Power Transfer System
Authors: Sokhui Won , Dongsheng Yang , Jiangwei Tian , Zixin Cheng , Songnam Jon
Published: July 2019

The characteristic of the Magnetic Resonance Wireless Power Transfer (MR-WPT) system is related on the coupling coefficients between coils, so it is very important to accurately measure mutual inductance. The method of measuring mutual inductance using the primary current and the secondary voltage, when the secondary circuit is opened, is commonly used and most reliable. However, a standard sine wave generator and a linear power amplifier are needed for measuring the mutual inductance. Due to the high frequency inverter of WPT system may be has distortion, it is not recommended to be as the sine wave generator for measuring the mutual inductance. The proposed method demonstrate that, although the output current waveform of the high frequency inverter and the voltage waveform on the secondary coil are highly distorted in PWM (Pulse Width Modulation) control mode, the base component’s amplitudes of these waveforms are investigated by FFT (Fast Fourier Transform), and then, the mutual inductance is calculated by using these values. According to the above contents, the experimental platform is built, and then the experiments on the different duty cycle ratio and the different frequencies, that is, including the different quantities of its high-frequency harmonics, has been done. In addition, the same operation as above is repeated on the different distances, and the results are compared with the theoretical calculation values. Consequently, the results show that the method is very close to the theoretical value, and it is very stable in whole distance range.
Design and Implementation of Power Market Operation Analysis Tag Library
Authors: Wang Qing-bo , Zheng Zong-qiang , Lyu Jing-wei , Shi Shu-hong
Published: July 2019

Responding to the continuous development of power reform and power market, referred to research of the power market operation, this paper designs operational analysis tag library, which is carried out in four dimensions: market supply and demand analysis, market structure analysis, market behaviour analysis and market operation analysis, to display and track the trend of power market operations more intuitively, and describes the operation status of the power market more comprehensively. Besides, Power Market Operation Analysis Tag Library is designed to deal with power trading management from a macro perspective with decision support.
Automatic control scheme development for process of sulfatizing roasting of iron-manganese concretions in fluidized bed
Authors: Darin A A , Gubin V V
Published: July 2019

The article describes the problem of regulating the process of sulfatizing roasting in a fluidized bed (FB) furnace of an enlarged laboratory facility for processing iron-manganese concretions (IMC) together with pyrite concentrate in a continuous mode. The features of roasting in the fluidized bed and technological factors affecting the control process and, as a consequence, the quality indicators of the technology are considered. The results of large-scale laboratory studies on a continuous installation of a FB controlled in manual mode are given. There is a scheme of adaptive automatic control of the roasting process in the FB with regulation of feed charge components. It allows maintaining a stable hydrodynamic state of the fluidized bed and control of key parameters, such as granulometric composition of the cinder, dust removal from the FB, blast pressure, temperature, etc., affecting the sulfatization of IMC metals.
Analysis of publications about the methods of static friction definition for bulk material
Authors: Erokhina O O
Published: July 2019

Static friction is one of the most important factors affecting the parameters of technological processes in the mining and metallurgical industries. To obtain reliable results of mathematical and computer simulations, there is a need to estimate a number of physical parameters of materials. With respect to the metallurgical and mining industries, the static friction parameter is of particular importance because of its applicability to relatively common process steps. Evaluation of static friction for bulk materials causes particular difficulties, which is justified by the variability of the particle size distribution, shape and density of particles. This article provides an overview of the existing methods for assessing static friction of bulk substances, their applicability, as well as the development trends of this scientific field.
Modeling viscous-plastic extrusion of oil-bearing materials pertaining to Bingham rheology
Authors: Gukasyan A V , Kosachev V S , Koshevoy Ye P
Published: July 2019

This paper defines the boundaries of changing the screw turn pitch to ensure maximum productivity in transporting a viscous-plastic fluid. A technique is proposed to determine the capacity of screw conduits of oil presses using Bingham viscous-plastic model of extrusion. The numerical modeling has shown a possibility for a significant increase in productivity of the FP oil press by means of optimizing the geometry of the press screw by changing its pitch to the optimal value.
Analytical model for estimating the shielding effectiveness of cylindrical connectors
Authors: Ivanov A A , Komnatnov M E
Published: July 2019

In this paper, an analytical model for evaluating the shielding effectiveness (SE) of cylindrical connectors was proposed. A connector shell may be fully or partially filled with dielectric. The results obtained up to 1 GHz using this model and the finite element method are in good agreement. According to this model, SE of the 2RMDT-connector used in the power bus was calculated and SE of 26 dB was obtained for the worst case.