中国电机工程学报
 
      设为首页      加入收藏
 
           About Journal | Current Issue | Contacts Us | Chinese
Office


    Author Center




   Quick Search
 
 
    Advanced Search    
Top Read Articles
Published in last 1 year |  In last 2 years |  In last 3 years |  All
Please wait a minute...
For Selected: View Abstracts Toggle Thumbnails
Social Energy Internet: Concept, Architecture and Outlook
WEI Xiaoguang, GAO Shibin, ZANG Tianlei, HUANG Tao, WANG Tao, LI Duo
Proceeding of the CSEE    2018, 38 (17): 4969-4986.   DOI: 10.13334/j.0258-8013.pcsee.180846
Abstract312)      PDF(pc) (664KB)(436)       Save
Energy internet is a user-centered smart system, which can provide a flexible way for users to employ the different types of energies by the real-time interaction among different systems; therefore human is the major part in the energy internet, and human behavior and interaction among persons have the great impacts on operation, planning, supervision and market of the system, et al. In the above background, the social energy internet was proposed based on the interaction between human and multi-energy system from the perspective of the social attributes of the energy internet. First, the importance and concept of the social energy internet was clarified from the angle of interactive relationships between human and system, multidisciplinary and multidimensional integration. Secondly, the physical features and research framework of the systems of multi-energy flow including energy flow, traffic flow, social flow and information flow considering social networks were analyzed. Furthermore, the planning, operation models and coordinate operation mode were constructed by considering the human behavior. Finally, the potential research topics on the social energy internet were proposed.
Reference | Related Articles | Metrics
Development and Prospect of IGCT Power Device in DC Grid
ZENG Rong, ZHAO Biao, YU Zhanqing, SONG Qiang, HUANG Yulong, CHEN Zhengyu, LIU Jiapeng, ZHOU Wenpeng, LÜ Gang
Proceeding of the CSEE    2018, 38 (15): 4307-4317.   DOI: 10.13334/j.0258-8013.pcsee.172714
Abstract235)      PDF(pc) (377KB)(313)       Save
Compared with power electronics systems in AC grid, the power electronics systems in DC grid have a lot of different characteristics, which provide opportunities for the application of integrated gate commutated thyristor (IGCT). This paper timely summarized the development trend of key power electronics systems in DC grid, and the application of IGCT in DC grid is prospected. Firstly, the application characteristics of IGCT and the key power electronics systems, included high-voltage high-power voltage source converter, medium or high-voltage high-power DC transformer and high- voltage high-power dc breaker, in DC grid were introduced. On this basis, by combining nature features of IGCT and voltage source converter, DC transformer and DC breaker, the application opportunities, basic scheme and technology advantages of IGCT in these systems were discussed comprehensively. At last, the problems and research suggestions were given for IGCT to be used in DC grid. The paper has significance to promote voltage conversation and power transfer with high-efficiency, high-density, high- reliability and low-cost in dc grid.
Reference | Related Articles | Metrics
Economic Dispatch of Microgrid Based on Two Stage Robust Optimization
LIU Yixin, GUO Li, WANG Chengshan
Proceeding of the CSEE    2018, 38 (14): 4013-4022.   DOI: 10.13334/j.0258-8013.pcsee.170500
Abstract220)      PDF(pc) (490KB)(281)       Save
A two stage robust optimization model with min-max-min structure was established to minimize the operation cost of microgrid under the uncertainty of renewable energy and load in this paper. The operation constraints and coordination of energy storage, demand response and controllable distributed generators etc. were considered in the model, and a parameter, named the budget of uncertainty, was introduced to adjust the level of conservatism of the robust solution against the modeled uncertainty. The model was decomposed into a master problem and a subproblem with mixed integer linear structure and solved based on the column and constraint generation algorithm and strong duality theory. Numerical cases show the effectiveness of the model and solution strategy. Furthermore, the boundary condition whether the energy storage wound be scheduled was given under the time-of-use mechanism, which can provide references to microgrid investors and distribution system operator for energy storage planning and the design of incentive mechanism, respectively.
Reference | Related Articles | Metrics
Parameter Analysis of Solar Power Tower System Driven by a Recompression Supercritical CO2 Brayton Cycle
ZHOU Hao, QIU Runchao, LI Yawei
Proceeding of the CSEE    2018, 38 (15): 4451-4458.   DOI: 10.13334/j.0258-8013.pcsee.171938
Abstract173)      PDF(pc) (907KB)(270)       Save
The supercritical CO2 recompression Brayton cycle model was established. The key parameters of solar power tower such as receiver efficiency, receiver area, heliostat field area, cost and solar energy supply ratio were studied. The results show that the Brayton cycle efficiency increases with the inlet temperature of the turbine. With the increase of the inlet temperature of the turbine, the receiver efficiency decreases and the heliostat field efficiency increases, and the efficiency of the whole plant increases first and then decreases, reaching the maximum efficiency at 750℃. With the turbine inlet temperature from 500℃ to 800℃, the receiver area reduced by 21.7%, the heliostat field area is also reduced by 22.2%. The solar energy supply ratio reaches highest (50%) at summer solstice, while at winter solstice is only 27.4%, and the average solar energy supply ratio is 39.7%. The average plant efficiency of summer solstice is slightly higher than that of the equinox by 0.8%. The efficiency of the winter solstice is lower than that of the equinox by 5.5%. The average efficiency of four typical days is about 20.36%.
Reference | Related Articles | Metrics
SOP Based Supply Restoration Method of Active Distribution Networks Using Soft Open Point
SONG Yi, SUN Chongbo, LI Peng, YUAN Kai, SONG Guanyu, WANG Chengshan
Proceeding of the CSEE    2018, 38 (15): 4390-4398.   DOI: 10.13334/j.0258-8013.pcsee.171769
Abstract171)      PDF(pc) (309KB)(188)       Save
Soft open point (SOP) refers to a novel power electronic device installed in active distribution networks (ADNs) to replace the traditional tie switch. The application of SOP will promote the flexibility and resilience of ADNs. Under a fault condition, SOP enables to provide voltage support and helps to expand the scope of power supply for the supply restoration. In this paper, a supply restoration model of active distribution system was established based on SOP, which is essentially a complex nonlinear programming problem. To obtain a high quality solution rapidly and accurately, the second order cone programming was adopted to solve this problem. Then, the modified IEEE 33-node system was used to verify the effectiveness and efficiency of the proposed method.
Reference | Related Articles | Metrics
Hierarchical and Zonal Optimization of the Energy Router Based Energy Internet
GUO Hui, WANG Fei, ZHANG Lijun, LUO Jian
Proceeding of the CSEE    2018, 38 (16): 4726-4737.   DOI: 10.13334/j.0258-8013.pcsee.171368
Abstract168)      PDF(pc) (739KB)(264)       Save
A hierarchical management framework of the energy internet including energy router (E-router) is proposed in the existing research. However, the current studies focus on the hierarchical architecture or the key equipment E-router. For the problem of economic dispatch in hierarchical control, much attention is paid to the interaction between microgrids and the utility grid. The optimal selection of transmission paths between multiple microgrids has not been considered after the E-router introduced into the energy internet. Therefore, a hierarchical and zonal optimization strategy of the E-router based energy internet was proposed in this paper. The lower-level is E-router based microgrid economic dispatch which aims at minimizing generation costs and implements distributed local optimization. While, the upper-level is routing transaction center which adopts the optimization strategy of graph theory based power pool transaction proposed in this paper. By selecting the minimum loss path for each power transaction to realize the benefits maximization and congestion managements. Finally, the effectiveness of the optimization strategy and model were verified by simulations.
Reference | Related Articles | Metrics
Reliability Evaluation of On-line Monitoring Device Over TransmissionLine Based on Data Driven Concept
LI Yan, TENG Yun, LENG Ouyang, YUAN Shun, CAI Zhiyuan
Proceeding of the CSEE    2018, 38 (15): 4410-4419.   DOI: 10.13334/j.0258-8013.pcsee.180785
Abstract166)      PDF(pc) (349KB)(180)       Save
Over the past few years, the backbone power grid of China have experienced a period of rapid expansion, the transmission channels of which cover a wide region of diversified terrain and complex environment, and it poses a huge challenge for ensuring the safe and stable operation of the important transmission channels. To solve the problems of fault identification and reliability evaluation of on-line monitoring devices over transmission line, various models of abnormal patterns were established based on in-depth analysis of abnormal data. Combining fault tree analysis and Bayesian network, a fault identification method for on-line monitoring device was proposed. Aiming at the shortcomings of the online device reliability evaluation method, a ternary judgment model including device state of failure, abnormality and normality was constructed. At last, the validity shows that this method can effectively determine the status of the on-line monitoring device and give the cause of failure and its occurrence probability, which can help the on-site operation and maintenance personnel to take targeted measures, which proved that this method has a broad prospect of engineering application.
Reference | Related Articles | Metrics
Research on a Predictive Direct Torque Control for the Drive Control System of Six-phase PMSM and Three-phase PMSM in Series
CHEN Guangtuan, ZHOU Yangzhong
Proceeding of the CSEE    2018, 38 (15): 4526-4536.   DOI: 10.13334/j.0258-8013.pcsee.171407
Abstract162)      PDF(pc) (1646KB)(374)       Save
Direct torque control (DTC) strategy for multi-phase drive based on switch vector table has many disadvantages, such as the large scale of the switch vector table, the switch vector can not keep optimal, et al. Therefore, a predictive DTC strategy based on voltage vector with zero zero-sequence voltage was built in synchronous rotating coordinate system of two motors to realize the accurate decoupling control of electromagnetic torque of two motors. In order to further reduce the zero-sequence current, the action time of zero voltage vector and the nonzero voltage vectors 21 or 42 was adjusted by the zero-sequence current loop. The experimental results show that compared with DTC based on switch vector table, the predictive DTC drive system proposed in this paper has a large reduction in torque ripple and current ripple, and the zero-sequence current is well near zero.
Reference | Related Articles | Metrics
Dynamic Characteristics Research and Calculating Tool Development ofFixed Structure of Stator End in a Novel Turbine Generator
ZHANG Qinglei, DUAN Jianguo, ZHOU Ying, ZHANG Yan
Proceeding of the CSEE    2018, 38 (15): 4555-4565.   DOI: 10.13334/j.0258-8013.pcsee.171647
Abstract161)      PDF(pc) (3024KB)(183)       Save
The vibration of the stator end is the main reason that restricts the long term stable operation of the turbine generator. Wearing of the bar insulation caused by vibration can lead to a serious short-circuit accident. The finite element modeling of dynamic characteristics of stator end winding fixed structure was studied for a 300MW 60Hz novel turbine generator. Through the analysis of bar, pressure plate, bracket, spring plate, core and the mutual connection between them, the finite element modeling method for different types of structural components and heterogeneous element fusion method were studied. Based on the beam element, shell element and solid element, a high accuracy modal calculating model was established to analyze the dynamic characteristics of the stator end winding. The modal experiments under different temperatures were carried out by the manufacturer to verify the feasibility of the modeling method and the validity of the model. The result shows that the model presented in this paper have less computational scale and higher calculation accuracy, which can be used as a reference for the optimization design of new products.
Reference | Related Articles | Metrics
Aging Characteristics of Interface Between Core and Sheath of Composite Insulators Under Water and High Temperature
NIE Zhangxiang, WANG Liming, YANG Cuiru
Proceeding of the CSEE    2018, 38 (15): 4601-4611.   DOI: 10.13334/j.0258-8013.pcsee.171580
Abstract161)      PDF(pc) (915KB)(189)       Save
The aging of the core and sheath interface of composite insulators is an important reason for the failure of composite insulators. To describe the change characteristics of properties of the interface in the aging process, the aging model of the interface under conditions of water and high temperature was proposed. It is thought that the aging of interface includes micro defects’ formation and extension, and the expansion of defects is dominant in the aging process. In addition, a new performance index of the interface based on the surface topography analysis of the mandrel was proposed: the interface image aging rate. The experiments were carried out on silicon rubber insulator and a novel cycloaliphatic epoxy resin insulator. The samples were aged in boiled water. And the performance of samples in different aging time were tested by the leakage current experiment and core-sheath shear separation experiment. The interface current, shear strength, were interface image aging rate as the performance index of interface state. The results show that the change of interface current and interface image aging rate in aging process are in accordance with S type curve in the aging model, which prove the model effective , interface defects’ extending is the cause of rapid aging of the interface; The shear strength cannot distinguish two sample of different aging time, while the other two indexes can; the interface defects extension index is inherent in the interface, can be used to evaluate the anti-aging properties of the interface for different types of composite insulator; the interface of the new epoxy insulator has better aging-resistance.
Reference | Related Articles | Metrics
An Open-loop Modal Analysis Method to Examine the SSOs Caused by Grid-connected DFIGs in a Multi-machine Power System
CHEN Chen, DU Wenjuan, WANG Haifeng
Proceeding of the CSEE    2018, 38 (14): 4064-4073.   DOI: 10.13334/j.0258-8013.pcsee.171763
Abstract157)      PDF(pc) (738KB)(209)       Save
Based on the modal resonance theory, an open-loop modal analysis method was proposed to investigate sub-synchronous oscillations (SSOs) caused by grid-connected doubly-fed induction generators (DFIGs) in a multi-machine power system. It is found that when an open-loop SSO mode of DFIG is approaching to an open-loop SSO mode of rest of the power system, the damping of one corresponding closed-loop SSO mode will be degraded due to the occurrence of open-loop modal resonance. The closeness of those open-loop SSO modes can indicate the risk of closed-loop SSO. Moreover, an open-loop modal index (OMI) is defined to evaluate the impact of open-loop modal resonance on power system stability. Furthermore, based on the SSO modes involved in modal resonance, the most dominant SGs and DFIGs can be identified by the proposed method. Therefore, countermeasures can be adopted to that dominant SG or DFIG to eliminate the SSO risk induced by grid-connected DFIGs. The correctness and effectiveness of the proposed method are validated through a modified IEEE first benchmark power system and an example of multi-machine power system.
Reference | Related Articles | Metrics
A Novel Differential Protection Scheme With Fault Line Selection Capability for HVDC Transmission Line
ZHENG Junchao, WEN Minghao, QIN Yu, CHEN Yu, YU Bin
Proceeding of the CSEE    2018, 38 (15): 4350-4358.   DOI: 10.13334/j.0258-8013.pcsee.171960
Abstract151)      PDF(pc) (452KB)(162)       Save
In order to solve the problem that the conventional differential protection for high voltage direct current (HVDC) transmission lines can't respond to internal faults quickly, a novel differential protection scheme was proposed in this paper. After voltage and current signals at both line ends are processed by the same low-pass filter the cut-off frequency of which is low enough, then the voltage distribution along the line can be regarded as linear distribution. The distributed capacitive current can be calculated by integrating the linear distributed voltage. After compensating for this current, the new differential criterion can be implemented. If the cut-off frequency is set lower, the distributed capacitive current can be ignored. In this case, the fault line can be selected by comparing the filtered differential current of both lines. A ±800kV Yun-Guang HVDC transmission system was built to test the performance of the new protection scheme. Comprehensive simulation results show that the proposed method not only can detect internal faults and select the fault lines correctly and quickly, but also can respond to internal faults with high ground resistance.
Reference | Related Articles | Metrics
Analysis and Compensation of Position Estimation Error in SPMSM Sensor-less Control Based on High Frequency Pulsating Voltage Injection
LIU Bing, ZHOU Bo
Proceeding of the CSEE    2018, 38 (14): 4232-4241.   DOI: 10.13334/j.0258-8013.pcsee.171683
Abstract150)      PDF(pc) (875KB)(171)       Save
Position estimation precision is of great importance in sensor-less SPMSM control based on high frequency pulsating voltage injection. Firstly, the position estimation errors caused by some non-ideal factors such as motor parameter asymmetry and current detection error were theoretically analyzed. Expressions of the errors were given. Simulations verified the above analysis. Secondly, a novel position observer was proposed in which all-pass filters were used to extract high frequency signal and to eliminate harmonic error. Parameter adaptive control and error feed-forward control were adopted to improve the dynamic performance of the position observer. Lastly, the proposed method was verified by experiments.
Reference | Related Articles | Metrics
Robust PI Controllers Design of Electrolytic Capacitor-less DC Charging Spot in Large Parking Lots
QIN Ling, KONG Xiaoxiao, XIE Shaojun, WANG Yafang, FENG Zhiqiang, QIAN Kejun
Proceeding of the CSEE    2018, 38 (15): 4514-4525.   DOI: 10.13334/j.0258-8013.pcsee.170443
Abstract150)      PDF(pc) (1143KB)(181)       Save
This paper presented a DC charging spot system suitable for large parking lots. Its first stage is electrolytic capacitor-less uncontrolled rectifier. The second stage is Superbuck converter acting as the charging interface. The DC charging spot has many advantages, such as high reliability, high efficiency, simple structure, easy control and low cost. However, its input voltage becomes a DC six-pulse wave. Hence, the right half plane zero (RHPZ) existence of the charging interface converter will change constantly with the variation of operation voltages. Furthermore, the pulsating input voltage will generate serious low frequency ripple (LFR) into the output side and adversely affect the battery lifetime. To ensure that the charger operates stably and LFR meets requirements throughout the whole operating range, this paper proposed a robust stability controller design method—globally scanning method—for variable structure system. The transfer admittance-based design criterion of the LFR robust suppression controller was also proposed. Firstly, the stability conditions of the charging system in constant current (CC) mode and constant voltage (CV) mode were given, separately. Secondly, the LFR transmission mechanism and its basic suppression strategy were analyzed. Then, the design criteria and methods for the input voltage feed-forward controller and the robust PI controllers were given. Finally, the correctness of theoretical analysis had been verified by a 1.8kW/80kHz prototype.
Reference | Related Articles | Metrics
Active Power Stratification Predictive Control Approach for Wind Power Cluster With Multiple Temporal and Spatial Scales Coordination
YE Lin, ZHANG Cihang, TANG Yong, SUN Bohao, ZHONG Wuzhi, LAN Haibo, LIU Hui, LI Pai, HUANG Yuehui
Proceeding of the CSEE    2018, 38 (13): 3767-3780.   DOI: 10.13334/j.0258-8013.pcsee.171685
Abstract146)      PDF(pc) (930KB)(248)       Save
Reference | Related Articles | Metrics
Self-similarity and Flow Field Characteristics of Horizontal Axis Wind Turbine Wakes
ZHANG Xuyao, YANG Congxin, GAO Zhiteng, LUO Song
Proceeding of the CSEE    2018, 38 (15): 4482-4489.   DOI: 10.13334/j.0258-8013.pcsee.171090
Abstract144)      PDF(pc) (1446KB)(159)       Save
In order to elucidate the wake characteristics of horizontal axis wind turbine operating in uniform inflow, by using the shear stress transport turbulence model, a rotor of 33kW two-blade horizontal axis wind turbine was simulated through solving the Reynolds time-averaged Navier-Stokes equations at different tip speed ratio. The results show that, in addition to the edge of the wake region, axial velocity deficit begin to remain the Gaussian self-similarity at a certain distance of downstream, and the greater the tip speed ratio is, the easier axial velocity deficit reach self-similarity state at downstream of wind turbine. Meanwhile, with the increase of the tip speed ratio, the wake expansion effect is more obvious and the tip vortices and root vortices break down early with the process of vortices propagate downstream. Within the range of two rotor diameters downstream of the turbine, the vorticity strength of tip vortices and root vortices decrease gradually with the increase of the distance from the wind turbine rotor, but the size of the vortex core is increasing. At the same axial position of wake region, the vorticity strength of tip vortex is always greater than that of the root vortex.
Reference | Related Articles | Metrics
Economic Optimization Study of Mix-burning Coal Slime Circulating Fluidized Bed Boiler
ZHANG Wei, GAO Mingming
Proceeding of the CSEE    2018, 38 (16): 4807-4814.   DOI: 10.13334/j.0258-8013.pcsee.172110
Abstract142)      PDF(pc) (417KB)(108)       Save
At present, mix-burning coal slime in circulating fluidized bed (CFB) boiler is an effective way to cleanly use low heat value fuels in a large scale. On the basis of the 300MW CFB steady-state operating data, least squares support vector machine (LS-SVM) was used to build the energy cost model, which described the relationship between the operating parameters and the energy cost; Within the safety threshold range of each control variable, the genetic algorithm (GA) was used to optimize the typical CFB parameter settings to establish an expert knowledge base (EKB) offline; The economic utility was introduced into association rule measurement standards, and the improved fuzzy association rule mining (IFARM) algorithm was used to extract the associations between optimal control variables and unit load from the off-line EKB, so as to achieve fast guidance on online optimization and adjustment of mix-burning coal slime CFB under load command.
Reference | Related Articles | Metrics
Research on Pricing Model and Strategy of Electric Vehicle Charging and Discharging Based on Multi View
CUI Jindong, LUO Wenda, ZHOU Niancheng
Proceeding of the CSEE    2018, 38 (15): 4438-4450.   DOI: 10.13334/j.0258-8013.pcsee.171958
Abstract142)      PDF(pc) (410KB)(195)       Save
With the booming of the electric vehicle industry, the pricing models and strategies of electric vehicles have stood out as the focus of current researchers and scholars. This paper is first designed to introduce the classification rationale of current electric vehicle charge and discharge pricing, and explore the realization mechanism of the orderly charge and discharge pricing models of electric vehicles as well as the advantages and disadvantages of each model from maximizing the benefits of power grids, charging stations, users and achieving a win-win result between suppliers and consumers. Then it elaborates on the corresponding optimization direction. Finally, a multi-objective charging optimization model based on time-of-use price is proposed with the security of power grid operation and the individual needs of users and the interests of all parties taken into account. The research data has verified the effectiveness and efficiency of this model as different electricity pricing plans will guide the users to adjust their electricity-using habits, thus deviating the load curve of power grids to ensure the safety of power grids, and interests of all parties concerned.
Reference | Related Articles | Metrics
A Double Vectors Selection Direct Torque Control Strategy of Permanent Magnet Synchronous Motor
XU Yanping, LI Yuanyuan, ZHOU Qin, LI Zehui
Proceeding of the CSEE    2018, 38 (17): 5211-5218.   DOI: 10.13334/j.0258-8013.pcsee.171814
Abstract139)      PDF(pc) (522KB)(242)       Save
In the duty cycle direct torque control (DTC) strategy, an effective voltage vector and a zero vector were selected in a sampling period. There were still obvious torque and flux ripples because the second voltage vector was only a zero vector. In order to reduce torque and flux ripples, a vectors double selection direct torque control of permanent magnet synchronous motor (PMSM) strategy was proposed. In this strategy, there were two voltage vectors in each sampling period. The first voltage vector was selected according to the switching voltage vector selection table and the second voltage vector was selected by the minimum principle of torque and flux errors. The durations of two vectors was calculated through torque deadbeat control method. The second vector was no longer just zero vector, but extended to arbitrary voltage vector. Experimental results show that compared with the duty cycle DTC, the proposed strategy can expand the range of optional voltage vectors and effectively reduce torque and flux ripples.
Reference | Related Articles | Metrics
Influence of AC Unbalanced Faults on DC System of Hybrid AC/DC Microgrid
XU Kuo, WANG Wanjun, JIA Lihu, ZHU Yongqiang, XIA Ruihua
Proceeding of the CSEE    2018, 38 (15): 4429-4437.   DOI: 10.13334/j.0258-8013.pcsee.171284
Abstract139)      PDF(pc) (474KB)(211)       Save
As the low voltage and small power capacity of hybrid AC/DC microgrid, the case which causes harmonic disturbance on DC side is less, therefore, there is no need to configure DC harmonic protection as the DC transmission field. However, the influence of AC disturbances caused by AC unbalanced faults on the DC system should not be neglected. The influence of disturbances on DC system, which is caused by AC unbalanced fault, was analyzed deeply, and the generation principle of first and second harmonic were studied firstly. And then, combined with three typical distributed generation (DG) control strategies, the response of DG control system to AC harmonic disturbances was analyzed, and the inner-loop reference current expression with perturbation component was proposed to analyze the influence. After that, simulation tests based on PSCAD/EMTDC were carried out to analysis the response of DC side and verify the above theoretical analysis. Finally, combined with the influence of AC disturbances, the suggestions for the design of hybrid microgrid protection system were proposed.
Reference | Related Articles | Metrics
Study on Frequency-domain Modeling and Time-varying Characteristics of DFIG Input Impedance With Excitation Under Static Reference Frame
LIAO Kunyu, TAO Shun, YAO Liting, XIAO Xiangning, YANG Lin
Proceeding of the CSEE    2018, 38 (16): 4886-4897.   DOI: 10.13334/j.0258-8013.pcsee.171858
Abstract136)      PDF(pc) (695KB)(152)       Save
Though the mechanism of time-varying sub-synchronous resonance (SSR) frequency in the series compensated transmission system based on doubly-fed induction generator (DFIG) has been studied, it is still necessary to clarify the mechanism more clearly. The modeling of input impedance could concisely analyze the characteristics of time-varying SSR frequency physically. However, the excitation has never been considered in DFIG impedance models. Thus, utilizing the small-signal analysis and harmonic linearization methods and considering excitation and disturbance phase sequence, the frequency-domain input impedance model was established in the stator static reference frame, which contains rotor current controller and phase-locked loop (PLL).The analytical impedance formula and equivalent circuit topology diagram were given. Also the physical meaning of PLL was explained. After introducing the stability criterion based on the input impedance and analyzing the influence factors of DFIG input impedance and the system stability, the time-varying characteristics of DFIG input impedance was proposed and studied. From the perspective of impedance, the physical mechanism of time-varying SSR frequency in DFIG series compensated transmission system was revealed. In PSCAD platform, the simulation cases verify the accuracy of the established model and its derivative conclusion as well.
Reference | Related Articles | Metrics
Fixed Frequency LCC Resonant Converter Design With Wide Zero Voltage Switching Range
LIN Leiming, XU Jianping, CHEN Yiming, MA Hongbo
Proceeding of the CSEE    2018, 38 (16): 4846-4854.   DOI: 10.13334/j.0258-8013.pcsee.170850
Abstract135)      PDF(pc) (590KB)(133)       Save
Compared with traditional variable frequency LCC resonant converter, fixed frequency LCC resonant converter benefits from simple design procedure of magnetic components. However, the lagging-leg switches of fixed frequency LCC resonant converter may lose ZVS operation under wide input voltage range or wide output power range, which results in high switching loss, low efficiency and serious EMI. To solve such problems, a passive auxiliary network consisting of auxiliary inductor and block capacitor was added between the leading and lagging legs, which assisted the ZVS operation of LCC resonant converter in wide input voltage range and wide output power range. Meanwhile, such LCC resonant converter was conducive to component selections due to the reduced resonant current. This paper elaborately analysed the steady state operation of proposed LCC resonant converter, based on which the ZVS condition was derived and a step-by-step parameter design procedure was built. In order to verify the correctness of theory analysis, a 500W/48V experimental prototype was built, which showed the proposed LCC resonant converter maintained ZVS operation with wide input voltage and output power range.
Reference | Related Articles | Metrics
Time-domain Modeling and Dynamic Simulation of the Grid-connected CHPs
XIE Da, CHEN Aikang, GU Chenghong, TAI Jun
Proceeding of the CSEE    2018, 38 (13): 3735-3747.   DOI: 10.13334/j.0258-8013.pcsee.171393
Abstract135)      PDF(pc) (649KB)(195)       Save
Reference | Related Articles | Metrics
Robust Biennial Scheduling of Cascade Hydropower System Considering With the Multi-band Uncertainty Set of the Inflow
GE Xiaolin, ZHONG Junling, FU Yang
Proceeding of the CSEE    2018, 38 (17): 5097-5106.   DOI: 10.13334/j.0258-8013.pcsee.172172
Abstract130)      PDF(pc) (300KB)(165)       Save
The mid-long term uncertainty and temporal correlation of the inflow of cascaded hydropower system are deeply related to the biennial hydropower scheduling. For improving the scheduling of the system in all possible scenarios, robust optimization theory was introduced into the biennial scheduling of cascade hydropower system. And considering with the temporal distribution characteristics of natural inflow of cascaded hydropower stations and the correlation of whole watershed, a multi-band uncertain set was proposed to describe the random factors of hydropower operation, which can reduce the conservativeness of traditional robust optimization. Finally, a two-stage optimization model of economic and safety coordination was established, and the optimized scheduling scheme with robust feasibility was obtained based on dual theory and mixed integer quadratic programming. Case studies show that the proposed robust optimized scheduling method for cascade hydropower system is more efficient than the scenario programming method, and the multi-band uncertain set can effectively improve the economics of the scheduling scheme.
Reference | Related Articles | Metrics
Theory of Aggregation Kernel of Turbulence and Brown Synergizing Vapor Condensing on the Surface of PM and Its Numerical Simulation
MI Hang, WANG Chunbo
Proceeding of the CSEE    2018, 38 (17): 5126-5133.   DOI: 10.13334/j.0258-8013.pcsee.172220
Abstract129)      PDF(pc) (560KB)(195)       Save
Reference | Related Articles | Metrics
Fast Solving of Day-ahead Power System Scheduling Chance-constrained Model Based on Improved ε -constrained and Deterministic Transform by Sampling
LI Zhiwei, ZHAO Shuqiang, LI Dongxu, ZHANG Tingting
Proceeding of the CSEE    2018, 38 (16): 4679-4691.   DOI: 10.13334/j.0258-8013.pcsee.171835
Abstract129)      PDF(pc) (715KB)(165)       Save
In the context of a high proportion of renewable energy access to electric power system, a multi-energy power scheduling model was established, after considering the uncertain output of wind power and photovoltaic power generation. In order to solve the large-scale scheduling model using commercial solver, the problem of dealing with the multi-objective and chance-constraint was studied. In the process of multi-objective optimization problem, the existing ε -constrained method was improved from the viewpoint of improving the uniformity of Pareto frontier set. The multi-objective optimization problem was transformed into a series of single-objective optimization problem with parameters, and the Pareto frontier set with multi-objective optimization was obtained by changing the value of the parameter. With regard to the chance-constrained constraints, a deterministic transformation method based on sampling was proposed, which transforms the opportunity constraint into multiple mixed integer constraints. According to the characteristics of the model which the random variables can be separated from the optimize variables, the transformation model was further simplified, which greatly reduces the calculation time of the chance-constrained programming and achieves the goal of solving the model within the required time. Finally, an example was given to demonstrate the effectiveness of the proposed method.
Reference | Related Articles | Metrics
Numerical Simulation Study of Low-heating-value Gas Turbine Nozzle Melting
QIN Ye, ZHANG Bo, YAN Shu, MU Yanfei, SHI Shaoping
Proceeding of the CSEE    2018, 38 (15): 4459-4466.   DOI: 10.13334/j.0258-8013.pcsee.171629
Abstract128)      PDF(pc) (993KB)(131)       Save
Low-heating-value gas turbine is the core equipment of an integrated gasification combined cycle (IGCC) plant. Aiming at serious burner nozzles melting of the low-heating-value gas turbine, computational fluid dynamics (CFD) was employed to construct the numerical model of the combustor and burner to analyze the reasons, considering the structure of the low-heating-value burner, fuel characteristics, and actual operation condition of the gas turbine. The CFD model shows that a small amount of syngas flows out of the flame stabilization holes of the nozzle. Then, it was pressed to the nozzle wall by air and burns there, which leads to high temperature regions and possible melting of the nozzle. To solve this problem, adding a baffle ring above the flame stabilization holes was proposed. The solution was examined by the CFD numerical model and shows that the highest nozzle wall temperature reduces from 1666K down to 1076K, far blew the melting temperature.
Reference | Related Articles | Metrics
Study on the Discharge Decomposition Characteristics of an Environmental-friendly Insulating Medium C5F10O
LI Yi, ZHANG Xiaoxing, XIAO Song, HUANG Liqun, TANG Ju, DENG Zaitao, TIAN Shuangshuang
Proceeding of the CSEE    2018, 38 (14): 4298-4306.   DOI: 10.13334/j.0258-8013.pcsee.170774
Abstract127)      PDF(pc) (1377KB)(117)       Save
Recently, the CnF2nO species have received much attention in the field of alternative gases, particularly C5F10O and C6F12O, both of which have a very low global warming potential (GWP) and excellent insulation properties. Due to its excellent insulation performance, foreign scientific research institutions and companies begin to study the material and its mixture, and there are few studies on its decomposition characteristics under discharge. In this paper, based on the density functional theory, the stability of C5F10O and its possible decomposition path were analyzed. At first, the ionization energy of C5F10O was calculated, and the possible position of the reaction in the molecular structure was determined based on the frontier molecular orbital theory. Secondly, the possible decomposition pathway of C5F10O, the formation mechanism of the decomposition products and the corresponding energy changes were analyzed. Finally, the C5F10O/N2 gas mixture was tested by using gas insulated test platform,the gas components in the gas chamber before and after breakdown were analyzed based on gas chromatography mass spectrometry (GC-MS), the insulation properties of the decomposition products and the dynamic equilibrium processes of various particles during the discharge process were discussed. The results show that the formation of CF3CO·, C3F7· or C3F7CO·, CF3· radicals is most likely to occur during the decomposition of C5F10O, and further reactions of various free radicals will generate CF4, C2F6, C3F8, C3F6, C4F10, C5F12, C6F14. The products have strong insulating properties, and the dynamic equilibrium between C5F10O molecules and free radicals exists, both of which ensure the insulation performance of the system. The test results showed that with the increase of breakdown times, the content of C5F10O decomposition products increased, and the growth rate of CF4, C2F6 and C4F10 was higher than that of C3F8 and C6F14.The conclusions provide theoretical basis for further research of insulation properties and synergistic effect of C5F10O gas mixture, and provide a reference for the study of CnF2nO environmental- friendly medium.
Reference | Related Articles | Metrics
Influence of System Structure on Multi-infeed HVDC Short Circuit Ratio
ZHANG Xiaohu, CHEN Chen
Proceeding of the CSEE    2018, 38 (16): 4777-4783.   DOI: 10.13334/j.0258-8013.pcsee.172282
Abstract127)      PDF(pc) (237KB)(202)       Save
Since the commutation of convertor relies on ac system voltage the relative strength of AC system is critical for line-commutated converter transmission. As more and more HVDC systems infeed to the load center, the power supply mode greatly changed and the stability and safety of AC / DC systems is faced up to severe challenge. Papers have been published on this issue, including DC optimal and/or coordinate control, DC infeed allocation, minimizing AC generation units in operation, dynamic reactive support and so on. However, adjusting AC grid structure to improve the stability level of AC / DC system has not been revealed. Recently condensers at the receiving terminal are supposed to improve the dynamic reactive power support, along with which the short-circuit current is raised up, however, series impedance is added to offset it . The comprehensive effect of all of them is not clear yet multi-infeed short circuit ratio (MISCR) is an effective indicator of transmission system strength. The branch additional method was applied on the system impedance matrix to analyze the influence of system structure on MISCR. It gives the guidance how to strengthen the multi-infeed AC/DC system by adjusting the power grid structure.
Reference | Related Articles | Metrics
Model Predictive Control and Power Balance Scheme of Dual-active-bridge DC-DC Converters in Power Electronic Transformer
AN Feng, SONG Wensheng, YANG Kexin
Proceeding of the CSEE    2018, 38 (13): 3921-3929.   DOI: 10.13334/j.0258-8013.pcsee.171555
Abstract127)      PDF(pc) (1370KB)(733)       Save
Reference | Related Articles | Metrics
Copyright  ©  PROCEEDINGS OF THE CSEE
Support by Beijing Magtech Co.ltd   support@magtech.com.cn