bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coordinative Control Strategy for Power Electronic Transformer with Microgrid Connection
Authors: Li Zheng , Zheng Tao , Ma Hongyue , Wang Jiahao 
Published: July 2019

Abstract
Power electronic transformer integrates rich forms of electrical interfaces and is able to realize a flexible, accurate and continuous regulation of the network power flow. It’s a promising power equipment to act as the ‘energy router’ in the energy internet, achieving a large-scale access and efficient utilization of distributed energy resources. To solve the DC-bus voltage fluctuation of PET caused by the randomness of the output power of microgrid, a coordinative control strategy between the input stage, isolation stage of PET and the microgrid is proposed. The frequency-domain analysing method is used compare the characteristics of the power fluctuation response under the proposed coordinative control strategy and a traditional control strategy. The simulation results indicate that the proposed control strategy can achieve the stability and fast convergence of DC bus voltage, which proves the correctness and advancement of the coordinative control strategy.
Research on PMSM Low-speed Sensorless Control Strategy based on Rotating High Frequency Injection Method
Authors: Tang Hui , Yin Dejun 
Published: July 2019

Abstract
In this paper, by studying the Permanent Magnet Synchronous Motor (PMSM) position sensorless control strategy, a method for error compensation of current responsed by high frequency error signal is proposed. Since the high-frequency carrier current contained in the stator current causes the erroneous adjustment of the current regulator, the control system contains a high-frequency error signal, which affects the motor rotor position and speed estimation accuracy. The high-frequency error voltage signal is extracted in the stationaryα − β coordinate system, and the high-frequency error response current in the stator current is estimated, and the estimation system is compensated. The PMSM position sensorless control system based on the rotating high frequency voltage injection method and the Matlab-Simulink system model of the error compensation are established. The results show that the speed and position estimation are more accurate after error compensation, and the steady-state error is smaller, which improves the smoothness of the motor at low speed.
Distribution Network Planning with Comprehensive Economy and Reliability
Authors: Du Wei , Lu Mengke , Li Deyi 
Published: July 2019

Abstract
From the perspective of reliability and economy of distribution network, this paper combines the layout of network frame and the configuration of section switch and contact line, and obtains many plannings that coordinate economy and reliability. Firstly, considering the grid planning, a multi-objective optimization planning model of the distribution network frame with the lowest investment and operating costs and the best reliability index is established. When solving the model, the minimum spanning tree algorithm is used to avoid the generation of infeasible solutions and reduce the computational burden. This paper improves the minimum spanning tree algorithm, when algorithm iteratively generates a new solution, the sum of the reduction rate of economic index and the growth rate of reliability index is used to be the objective function in the iterative process, so that the multi-objective problem is transformed into a single objective problem. The preference factor of the decision-maker is given by weight assignment. And the algorithm is extended to multi-power planning. Secondly, considering the configuration of section switch and contact line, the nonlinear mixed integer programming model corresponding to the system is established, and the Pareto optimal solution set is generated by the NSGA-II algorithm. Then, the Pareto optimal solution set is converted into a series of corresponding planning schemes that the designer can select. Finally, the validity and correctness of the proposed method are verified by the analysis of single-source and multi-source distribution network examples.
A Study on Power Quality Transient Disturbance Location Method
Authors: Zhang Huaying , Hu Ziheng , Li Yan , Ai Jingwen 
Published: July 2019

Abstract
Due to periodic variation of power signal and various disturbances present during sampling process, resulting background gradient affects the accuracy of disturbance detection. In order to solve this problem, this paper proposes a power quality transient disturbance location method based on morphological edge detection, and introduces a soft threshold quantitative evaluation method to improve its accuracy. Firstly, an evaluation method of filtering effect is proposed, and original signal is filtered by adaptively choosing size of structuring elements. Then, Top-Hat transform of morphological gradient is performed by flat structuring elements to suppress background gradient, and the location result is initially obtained. Finally, combined with soft threshold processing method, the location of power quality transient disturbance is realized. Simulation analysis of a series of power quality transient disturbances shows that this algorithm has accurate location results, strong capacity of resisting disturbance and good versatility.
Regeneration Technology of Ex-service SF6 Adsorbent Using Vacuum Heat Treatment
Authors: Wen Chunlei , Wei Gang , Hu Min , Yin Hua , Yang Jun , Li Cuiying , Zhang Haiyan 
Published: July 2019

Abstract
Ex-service SF6 adsorbent is toxic, and its direct dumping may cause environmental damages. Therefore, studying the environmental-friendly processing of ex-service SF6 adsorbent has important social values. In this study, the adsorption components of the ex-service SF6 adsorbent were analyzed by thermogravimetry. In order to study the most economical and effective regeneration method of SF6 adsorbent, the regeneration technology of vacuum heat treatment was proposed, and the regeneration theory of vacuum heat treatment concerning adsorbent was elaborated, then followed by the experiment of vacuum heat treatment. By combining with infrared spectroscopy, the content change of harmful ingredient in adsorbent was analyzed, focused on the confirmation of vacuum heat treatment regeneration temperature, regeneration time and vacuum pressure, and the test verification on adsorption isothermal curve was performed to determine the desorption capacity of SF6 molecular sieve adsorbent recycled. We found that vacuum heating can increase performance recovery rate by 85%–90%.
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.