Table of Content

25 November 2015, Volume 48 Issue 1

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13th Five-Year Power Planning

Research on Major Issues of the 13th Five-Year Plan Development of Power Industry

ZHANG Yunzhou, CHENG Lu

2015, 48(1):  1-5.  DOI: 10.11930/j.issn.10.11930.2015.1.1

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In the 13th Five-Year Plan and later periods, given the rare historic opportunity, the Chinese power industry will endeavor to adjust energy structure, control air pollution and reform end users’ energy consumption style, which will energize the transitions in electricity power development pattern. In this paper, the development situation of power industry in the 13th Five-Year Plan period is analyzed, and the strategies to resolve the dilemmas of balancing the relationships in different aspects for the 13th Five-Year Plan are proposed. In addition, some key issues related to the power demands, energy source supplies for power generation, power generation equipment installation and layout, new energy subsidies, power grid development, and power market reform are studied, which will be of great significance for making the 13th Five-Year Plan and energy policies.

14th Five-Year Power Planning

Research on Electricity Demand of China during the 13th Five-Year Plan and Med-Term- & Long-Term Periods

SHAN Baoguo, HAN Xinyang, TAN Xiandong, WANG Yongpei, ZHENG Yanan

2015, 48(1):  6-10.  DOI: 10.11930/j.issn.10.11930.2015.1.6

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It is of great significance to properly determine the forecasts about the national and local power demand trends in the 13th Five-Year Plan as well as the med-term and long-term periods. In this paper, three scenarios of economic and electricity demand growth are constructed to forecast the national and local power demands by 2020 and 2030 based on the established economy and electricity demand forecasting model. The results show that during these periods, China’s electricity demand will still have strong growth potentials, but the growth rate will decrease greatly after 2020. The North China, Central China and East China will always take the major role in electricity demand. By 2020, the total demand for electricity will be about 7 649 to 8 447 TWh with the peak load of 1 271 to 1 410 GW and the proportion of the electricity demand in North China, Central China and East China accounting for 63.7%~65.8%; by 2030, the total demand will be about 1 003 to 1 175 TWh with the peak load of 1 708 to 2 002 GW and the proportion of the electricity demand in North China, Central China and East China accounting for 61.5%~63.2%.

15th Five-Year Power Planning

Research on Development of Transmission Power Grid in 13th Five-Year Period

HAN Feng, SONG Fulong, LUO Jinshan, LU Chang

2015, 48(1):  11-14.  DOI: 10.11930/j.issn.10.11930.2015.1.11

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The 13th Five-Year period is crucial for speeding up the energy and power development mode transitions. This article summarizes the main achievements of gird development during the 12th Five-Year Plan period, analyzes the situation and challenges of power grid development, and puts forward the ideas and major goals of power grid development in the 13th Five-Year Plan period. It also presents that power grid development should not only ensure power supplies for socio-economic development, but also enhance the grid itself and advocate clean and high efficient energy consumption. As China’s main power flows are transferred from west to east and from north to south, in the development plan of power grids affiliated to the State Grid the infrastructure will be demonstrated as the sending ends located at the Northeast, Northwest and Southwest China while the receiving ends at the North China, East China and Central China. The construction of strong smart grid should be accelerated with the UHV power grid as the mainstay and the coordinated development of power grids at all voltage-levels to promote intensive development of large-scaled coal, hydropower, nuclear power and renewable energy bases, implement large-scaled and long-distance power transmission and achieve optimal energy resources allocation nationwide.

16th Five-Year Power Planning

Research on Power Flow and Power Source Installation Planning Scheme during the 13th Five-Year Period

BAI Jianhua, YAN Xiaoqing, CHENG Lu

2015, 48(1):  15-20.  DOI: 10.11930/j.issn.10.11930.2015.1.15

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The period of the 13th Five-Year(2016-2020) is an important opportunity period for the state’s energy and power industry to change its developing mode and optimize its structure and layout. Under the new circumstances of continuous growth of electricity demands, more strict constraints on ecological environmental capacity and large-scaled renewable energy exploitation of wind power and solar power etc., it is inevitable to optimize the allocation of energy in a wider range. Reasonable and scientific power flow planning turns out to be of the most importance. Therefore, a new method of power flow planning applicable to the current situation is proposed in this paper. Based on this new method, the nationwide power flow planning for the 13th Five-Year period is conducted, which can bring forth remarkable social and economic benefits.

17th Five-Year Power Planning

Considerations of Distribution Network Development for the 13th Five-Year Period

LIU Haibo, HU Bin, WANG Xuyang

2015, 48(1):  21-24.  DOI: 10.11930/j.issn.10.11930.2015.1.21

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The distribution network, which is directly interfaced to electricity consumers, is not only the key part to ensure the electricity power transmitted, received and consumed by the users, but also the critical infrastructure to improve the people’s livelihood. To make the distribution network development compliant to the high-quality and intelligentization requirements in the 13th Five-Year-period, based on the analysis of the present situation, the challenges and opportunities of the distribution network are presented in terms of economic and social development, high power supply reliability requirements, distributed energy access, multiple load access and external construction environment changes. The overall development threads of constructing flexible, reliable and efficient distribution networks with reasonable structure and advanced technique are promoted. The development principles of differentiation, standardization, flexibility and coordination are also proposed. At last, the recommendations on future distribution network construction regarding the distributed power sources and electric vehicles access, new urbanization and smart city construction are put forward from the viewpoint of planning and constructions.

18th Five-Year Power Planning

The Security and Stability of Power Grids in 13th Five-Year Planning and Countermeasures

QIN Qin, GUO Qiang, ZHOU Qinyong, QIN Xiaohui

2015, 48(1):  25-32.  DOI: 10.11930/j.issn.10.11930.2015.1.25

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Due to the inverse distribution of energy resources and productivity in China, the energy bases and the load centers are about 1 000 to 4 000 kilometers apart from each other, which needs a wide range of optimal energy allocation to ensure energy supplies. During the 13th Five-Year period of power grid planning, UHV will have entered a rapid development period. The planned national grid (excluding Southern power grid), which has a structure of three sending ends(i.e. the Northwest, Northeast and Southwest power grids) and one receiving end(North China-Central China-East China UHV synchronous power grid) will take shape and features AC/DC hybrid power and multi-infeed HVDC systems. The power stability will face new challenges due to the upgrade of DC transmission capacity and the application of large capacity UHV transformers. Higher requirements on the frequency stability of sending power grids are put forward owing to the concentrated multiple HVDC transmission to the load centers. The security assessment in aspects of short circuit current, static security, transient stability, dynamic stability and voltage stability made by the State Grid Simulation Center indicates that the main security and stability issues faced by the 13th Five-Year power grid planning will be effectively solved by the following countermeasures including the construction of strong AC and strong DC power grid structure, the adoption of AC/DC coordination control strategy and the timely breakup of 1 000/500-kV electromagnetic looped networks.

19th Five-Year Power Planning

Study on the Major Issues of Renewable Energy Development

LI Qionghui, WANG Caixia

2015, 48(1):  33-36.  DOI: 10.11930/j.issn.10.11930.2015.1.33

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Great achievements have been made for the development of renewable energy in China since 2006. However, several problems have been encountered such as the lack of coordination between the developments of wind power and power grids, the difficult position of wind integration in regional power systems with high wind penetrations, and the delay of renewable energy subsidy payment. As the 13th Five-Year is a critical period for the renewable energy development in China, the existing pattern of renewable energy development using the replication of current technology and highly relying on the government subsidy can hardly survive. Three critical issues in renewable energy development need to be addressed properly, i.e., incentive policy adjustments, coordinated planning of renewable generation and other types of generation as well as power grids, and energy accommodation generated from the large renewable energy bases in China.

Generation Technology

Diagnostic Analysis on Insufficient Output of Circulating Water Pumps for a 300-MW Unit

MA Tingshan, CHENG Dongtao, XU Pengjiang, JU Wenping, CHEN Kai, REN Lijun

2015, 48(1):  37-39.  DOI: 10.11930/j.issn.10.11930.2015.1.37

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The circulating water flow is insufficient since the commissioning of a 300-MW generating unit, which greatly influences the economical efficiency of the unit. The testing analysis shows that the designed resistance of the circulating water system is less than the actual value, which leads to the insufficiently designed output of the circulating water pumps, so that the circulating water flow is too small to maintain the normal vacuum. According to the actual resistance characteristics of the circulating water system, new circulating water pumps are selected and substituted for the original ones, making the net coal consumption be reduced by 1.174~1.200 g/（kW·h）. The retrofit has achieved good effects. Therefore, some considerations in circulating water pump design and type selection are put forward.

Study on SBM-Based Failure Prognostic System for Power Generation Equipments

TENG Weiming, LIU Lin, LU Weiming, ZHANG Zhenwei, HU Boyong

2015, 48(1):  40-46.  DOI: 10.11930/j.issn.10.11930.2015.1.40

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Generally, the monitoring system for power generation equipments adopts absolute value to issue alarms when the operating parameters exceed the set values. This single monitoring method makes it difficult to notice the early signs of the equipment abnormalities and then keep the track of their further development, which may eventually cause the forced outage of equipments. In this paper, a modeling technique based on similarity mechanism(SBM) is proposed in which a model matrix is established to simulate the real equipments by analyzing the actual operation data with mathematical method. Then, the deviation is obtained by comparison between the actual operation value and the calculated value on the model. If it is more than the preset deviation, the alarm will be triggered. This system can display the online dynamic process of the system parameter changes, reflect how well the system is operated, and timely remind the maintenance personnel of equipment maintenance. At last, the practical applications of the system are demonstrated with case studies.

Numerical Simulation of High Temperature Corrosion Reduction by Deflected Secondary Air in a Tangentially Fired Ultra Supercritical Boiler

DENG Zhongyi, YU Yongsheng, XIE Hong, CHEN Jian

2015, 48(1):  47-51.  DOI: 10.11930/j.issn.10.11930.2015.1.47

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Aiming at the phenomenon of high temperature corrosion in a large area of the water wall in the routine operation of an ultra supercritical boiler, the numerical simulation using the Fluent software for computational fluid dynamics is conducted. The simulation results indicate that there exists the phenomenon of primary air sweeping the water wall and the concentration of CO in the water wall surface area is high, which is apt to cause high temperature corrosion. The numerical simulation results are proved to be reliable as they are consistent with the test results. Therefore, the simulation on the deflected secondary air alleviating the high temperature corrosion is carried out, which indicates that this method can effectively prevent the high temperature corrosion and it can provide a reference for future’s modification.

Operation Control of Indirect Air-Cooling Generating Unit in Extreme Climate Environment

YANG Zhijun

2015, 48(1):  52-55.  DOI: 10.11930/j.issn.10.11930.2015.1.52

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There are risks for indirect air-cooling generators running under extreme climate conditions. Without proper control, they would cause operation safety problems, such ase radiator tube bundle freezing and great fluctuation in condenser vacuum. Based on the practical operation of two newly built units operating in extremely cold, hot and windy weather, this paper analyzes and studies the factors and mechanism that affect the unit secure operation in climate extremes. and a set of preventive measures are proposed to eliminate the risks. These measures can safeguard the indirect air-cooling units operating safely and reliably under extreme weather.

Entropy Weight Based TOPSIS Method for Nuclear Level ⅠForgings Quality Evaluation

LIN Liangsheng, LIU Li, ZOU Pingguo, CHEN Hong

2015, 48(1):  56-59.  DOI: 10.11930/j.issn.10.11930.2015.1.56

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To evaluate the quality of nuclear level Ⅰ forgings comprehensively and objectively, it is necessary to establish a set of method systems which are suitable for forging quality evaluation. According to the manufacturing process and final quality inspection which affect the quality of nuclear level Ⅰ forgings, the main process parameters are analyzed and the forging quality evaluation index system is established. By exploring the characteristics of TOPSIS method based on entropy weight, the evaluation model is established and applied to the core barrel forging material quality evaluation, and the core barrel forging material quality order is obtained. The results show that the TOPSIS method can evaluate the quality of nuclear level Ⅰ forgings effectively, scientifically and objectively; it is convenient to operate and easy to apply.

Effects of Lay-Up Protective Agent on Water and Steam Cation Conductivity

ZHANG Xiangjin, LI Yan, DENG Yuqiang, NI Ruitao, QI Dongdong

2015, 48(1):  60-63.  DOI: 10.11930/j.issn.10.11930.2015.1.60

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Octadecylamine and surface active amine are generally used as protective agents in boiler lay-up protection. In this paper, the comparative study on the application effects of the two kinds of protective agents is conducted, namely on the changes of main steam and condensate water hydrogen conductivity in wet unitsair-cooled units, and the units with or without condensate polishing treatment system that adopt octadecylamine or surface active amine protection agents during startup and shutdown. The results show that both kinds of protective agents are partly decomposed in the water and vapor system in the process of shutdown and startup, which causes significant increase of the hydrogen conductivity of the water and vapor system. In comparison with the octadecylamine agent, the surface active amine agent can maintain the normal commissioning of the condensate polishing system in the unit startup and shutdown processes so that the water and steam quality can meet the standards quickly and ensure secure operation. Therefore, the surface active amine agent is recommended as the boiler lay-up protective agent.

Optimization of Experimental Conditions for Alkaline Alumina Extraction from Coal Gangue

XIANG Yajun, JI Lichun, REN Genkuan

2015, 48(1):  64-67.  DOI: 10.11930/j.issn.10.11930.2015.1.64

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There exists valuable alumina in the industrial solid waste coal gangue which can become treasure when it substitutesfor bauxite for alumina extraction. However, the kaolin form of aluminum-silicon in the coal gangue has low activity, which has to be broken in high temperatures to change the alumina into soluble calcium aluminate in sodium carbonate solution. In order to achieve the maximal leaching rate of alumina in the coal gangue with lime sinter process, the experimental conditions for activation and extraction of coal gangue are optimized with orthogonal experiments respectively. The experimental results show that in the process of alumina extraction in coal gangue by the lime sinter process, the optimal alumina leaching efficiency can be as much as 89.5%. Therefore, the optimized experimental condition may provide a reference for industrial tests.

Parameter Simulation Methods for Generator and Its Control System Based on DSATools Simulation Tools

QIN Songtao, SHAO Changning, LI Ling, ZHAO Ran, LIU Mei

2015, 48(1):  68-75.  DOI: 10.11930/j.issn.10.11930.2015.1.68

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The knowledge of accurate parameters of the generators and their control systems is the basis for power system analysis. Exact on-line parameter identification is usually difficult to realize due to the limit of working conditions, this brings difficulty to the security check, index estimation, flow optimization and other works of the power system. A parameter recognition method based on the simulation model was presented in this paper. The simulation model of a generator and its control system was built with the DSATools, parameters were optimized by measures of curve fitting, and then the exact parameters simulation results can be gained. Finally, the generator and its control system of Pingban hydropower generator units were tested as an example, which confirmed the feasibility of parameter recognition with the simulation model.

Power System

Contrastive Study on Corona Characteristics of Aluminum Conductor Composite Core and Aluminum Conductor Steel Reinforced

GENG Jianghai, ZHOU Songsong, QI Xiaomei

2015, 48(1):  76-80.  DOI: 10.11930/j.issn.10.11930.2015.1.76

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In order to study the corona characteristics of aluminum conductor composite core (ACCC), corona onset tests of single ACCC-600/71 conductor and LGJ-630/45 conductor were performed based on the corona measurement system with small corona cage. The experimental result shows that: under clean and artificial smear conditions, the corona onset voltages of ACCC-600/71 conductors are higher than those of LGJ-630/45 conductor, which proves that ACCC-600/71 conductors can reduce the line losses and have good performance in energy saving and environmental protection. Surface contamination reduces the roughness factor of ACCC-600/71 and LGJ-630/45 conductors and greatly lowers the corona onset voltages. The bigger the particle size is, the higher the influence will be.

Fault Line Selection Algorithm Based on Correlation Analysis of Transient Information of Fault Signal in Neutral Un-effectual Grounded System

DAI Xusheng, HUANG Chun, YE Qian, WANG Feng, DONG Xuzhu, LENG Chongfu

2015, 48(1):  81-86.  DOI: 10.11930/j.issn.10.11930.2015.1.81

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In case of single-phase grounding fault in small current neutral grounding system, the transient ground fault current contains the information of the whole system’s fault characteristics. The main component of transient phase current of health line is capacitive current to ground. Considering the effect of inductance in the system, the differential current of health feeder is very small and the phase current waveform and zero sequence transient current are significantly irrelevant. Meanwhile the waveform of the fault line and differential current show a significant correlation. Taking the advantage of the feature of small current system in case of signal-phase fault, the fault phase can be detected by the approximation ratio of three phase bus voltage. Then the fault line can be diagnosed by using the correlation analysis and comparison of each line’s transient differential current and zero sequence current correlation. The simulation in MATLAB/SIMULINK is carried out to verify the feasibility of the proposed method.

Interference Analysis of Power Frequency Parameter Measurement for 1 000 kV Wanan-Zhebei UHV Transmission Line

MA Yue, LI Guoman, WANG Shaohua, CUI Zhuye, JIN Yongtao, JIANG Jianling

2015, 48(1):  87-91.  DOI: 10.11930/j.issn.10.11930.2015.1.87

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Interference analysis of power frequency parameter measurement of UHV transmission line is an important basis for selecting appropriate anti-interference test method and analyzing the testing result. The interference voltage signals of 1 000 kV Wannan-Zhebei UHV transmission line were tested during measuring the positive sequence and zero sequence parameters, and their spectrum characteristics was analyzed. On this basis, the field testing error of positive sequence parameters was also analyzed. The results show that the interference voltage has unbalance and time-variant features. Some difference exists between the power frequency parameter testing result obtained by power frequency method and that by variable frequency method. When the interference voltage is time-varied, the variable frequency method should be adopted to measure the power frequency parameter of transmission line.

Analysis on the Unbalanced Circuit Current of the 3/2 Wiring System of 1 000 kV UHV Nanyang Substation

LIU Tao, FANG Jinyan, CHENG Chaolei, HUANG Jianjin, XU Ruina

2015, 48(1):  92-97.  DOI: 10.11930/j.issn.10.11930.2015.1.92

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3/2 main wiring is used in the 1 000 kV system of UHV AC substation. Since the resistive unbalance in the main conductive circuit is significant and the power transmission capacity is large, unbalanced circulation exists in the 3/2 wiring system. In extreme case, some breakers’ single-phase current appears zero or even phase-inverted. Based on the UHV Nanyang substation, the zero-sequence of the unbalanced circulation and the cause are theoretically analyzed. The serious problems and consequences of the secondary system caused by zero-sequence circulation during large load operation are discussed and several solutions are proposed: the conflux current of two breakers is used for protection device; the minimum current of 3-phase brakes the zero-sequence module in single breaker; the conflux current of two breakers brakes single breaker zero-sequence module. This analysis is expected to call enough attention to be paid to the unbalanced circulation in the future projects.

Design of Slope Tower Used in 1 000 kV UHVAC Transmission Line in Mountainous Area

SONG Gang, CHEN Jiamiao, GUO Yong

2015, 48(1):  98-103.  DOI: 10.11930/j.issn.10.11930.2015.1.98

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The lightning shielding failure is the main cause of UHVAC transmission line fault，especially when it travels through mountainous area where lighting activities are frequent and the shielding effect is poor, the lightning trip out rate is higher. In order to reduce the rate of lightning shielding failure, a new type of tower called slope tower used in UHVAC single circuit transmission line in mountainous area was introduced in this paper. Compared with the conventional cup type tower, the cross arms of two phase conductors of slope tower are arranged on the downhill side, which can reduce the distance from conductor to ground, and the shielding failure trip out rate calculated by Electric Geometry Method can be greatly reduced. An analysis of the internal structure force, the electromagnetic environment level and the project cost shows that the slope tower has many advantages and is applicable to UHVAC single circuit transmission lines in mountainous area with heavy lightning, and it can provide a reference for the lightning protection design of UHVAC transmission line in mountainous area.

Structure Parameters of 550 kV SF6 Gas-Insulated Bushing Insulated Shielding Layer for High Altitude Localities

WANG Haibo, DI Qian

2015, 48(1):  104-106.  DOI: 10.11930/j.issn.10.11930.2015.1.104

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The impacts of the structure parameters of insulated shielding layer of 550 kV SF6 gas-insulated GIS bushing for high altitude localities on the electric field distribution is introduced. The impacts of shielding layer structure of different combinations of parameters on the maximum electric field strength are researched with the finite element method based on single shielding layer structure. And the impacts of shielding layer structure with different heights on the electric field distribution of the bushing are also researched. By optimizing the best shielding layer height and the best parameter combination of the shielding layer structure, the ideal internal and external electric field distribution of the bushing can be obtained. The internal and external electric field distribution of 550 kV SF6 gas-insulated GIS bushing for high altitude localities is thus effectively solved. A theoretical basis for design of 550 kV SF6 gas-insulated bushing insulation structure for high altitude localities is provided.

Research on Reactive Power Optimization Using Quantum Evolutionary Algorithm Based on NW Small World Model

MENG Anbo, YUE Longfei, XING Linhua, CHEN Yucheng, LI Yang

2015, 48(1):  107-114.  DOI: 10.11930/j.issn.10.11930.2015.1.107

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In view of the premature convergence problem of quantum evolutionary algorithm(QEA), a novel NW(Newman-Watts) small- world quantum evolutionary algorithm is proposed for reactive power optimization. This algorithm introduces the NW small world network model, and dynamically changes the neighborhood topology of each individual among population through a novel random adding edge method, which not only guarantees the diversity of evolution population, but also improves its balance capability of global exploration. Finally, the proposed algorithm is applied to address the reactive power optimization problem in IEEE 14-bus system and IEEE 30-bus system. The simulation analysis shows that the proposed NW small-world quantum evolutionary algorithm outperforms the standard QEA both in global search capability and convergence precision.

Improvement Measures and Economy Analysis on 10 kV Direct Power Supply Load from 220 kV Substations

ZHANG Qiaoxia, CHANG Gang, XIAO Zheng, CAO Xiaoqing

2015, 48(1):  115-120.  DOI: 10.11930/j.issn.10.11930.2015.1.115

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In order to coordinate the locations of 220 kV and 110 kV substations, a statistic analysis is made of the 220 kV substations based on the direct power supply situation from the 10 kV side of the 220 kV three-volume transformers in a province. The existing problems of direct power supply are studied and corresponding solutions are proposed from both technical and economic aspects. The solutions include: combining the distribution network planning with the 10 kV direct supply loads, optimizing the structure of the distribution system, reasonably utilizing the capacity of 220 kV substations, direct supplying power to the nearby 10 kV load system from the 220 kV substations, and controlling the delivery distance to ensure the system reliability. The above-said solutions can exploit the potential of the existing power network, decrease the line power loss, and make the distribution of the power grid more reasonable.

Modeling and Current Stabilization Coordinated Control Strategy of Rectifier System in an Aluminum Smelter

LIU Haoming, MENG Xia, GAO Yuan, YUAN Xiaoling

2015, 48(1):  121-126.  DOI: 10.11930/j.issn.10.11930.2015.1.121

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The structure of high-power DC supply system of the aluminum smelter is described and the models of electrolytic cell, saturable reactor(SR) and on load tap changer(OLTC) are built respectively. A coordinated control strategy based on SR and OLTC is proposed to keep the DC current stable, in which the OLTC is used for discrete coarse control of series current and the saturable reactor is used for continuous fine control. The proposed coordinated control strategy has good performance when a large disturbance occurs, such as single unit is out of operation, or the anode effect occurs, et al. The rectifying system of 6 units is built by PSCAD/EMTDC, and simulation is carried out on grid voltage and load fluctuations. The simulation results show that the control strategy can keep the DC system on the optimum operation status and the series current stable.

Novel Control Method for Hysteresis-band Current with Quasi-constant Frequency based on Current Change Rate

GU Zhenjiang, LU Yi, HU Yinghong, LIU Shaoyu

2015, 48(1):  127-130.  DOI: 10.11930/j.issn.10.11930.2015.1.127

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Switching frequency of hysteresis-band current control is inconstant, which leads to the difficulties of filter design and the problem of sampling rate. On the basis of analyzing the relationship between hysteresis-band and switching frequency, a novel hysteresis-band current control method with quasi-constant frequency based on current change rate is proposed to solve this problem. With rapid response and good stability, the proposed method can adjust the hysteresis band according to the current change rate so as to keep the switching frequency constant. As this method doesn’t require the information about the system’s parameters, it is simple and easy to be implemented. Simulation and experimental results have validated the method’s effectiveness.

Study on the Probabilistic Optimal Capacity of Energy Storage in Microgrid

MA Xiaobo, CHEN Min, ZHOU Xinnan

2015, 48(1):  131-136.  DOI: 10.11930/j.issn.10.11930.2015.1.131

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Renewable energy power generation represented by wind power and photovoltaic power is undispatchable and sensitive to the outer environment, which brings great challenge to safe operation of the micro-grid and can be effectively solved by connecting an energy storage system in the microgrid. The method to determine the energy storage capacity is studied when a micro-grid is operated in island state, and a probabilistic method is proposed to determine the optimal energy storage capacity. The power difference between the microgrid’s dispataching capacity and the load demand is firstly calculated, and then the maximum charging and discharging power of the energy storage system is determined through the probability density function curve. The optimal capacity of energy storage system can be obtained according to the probability density function curves of the accumulative charging and discharging power of the storage system at different times, which can improve the economic benefit and renewable energy utilization. The proposed method, when used for determine the microgrid’s energy storage capacity, is straightforward in solution and small in needed storage energy capactiy.

Smart Grid

Researches on the Online Monitoring System for Partial Discharges of Power Cables in Smart Substations

JIA Zihang, LI Yanqing

2015, 48(1):  137-141.  DOI: 10.11930/j.issn.10.11930.2015.1.137

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An online monitoring system in smart substations for partial discharges of cables based on IEC61850 was proposed. The detection principles and methods of partial discharges in cables were analyzed. A monitoring hardware system based on fiber synchronous triggering and fiber networks was designed as well as a monitoring software system which is a high-speed acquisition system based on UDP protocol and producer/consumer models. Moreover, this monitoring system’s results can be analyzed by an expert system and then shared via IEC61850 protocol. Finally, two kinds of partial discharge model experiments were simulated to verify the monitoring system. The results show that the system runs well, the monitors can distinguish partial discharge signals accurately, whose results can be shared via IEC61850 protocol.

Application Research on High Frequency Switch Power Supply Technology

ZHU Shipan, ZHANG Yongchao, SHI Zhongcheng

2015, 48(1):  142-145.  DOI: 10.11930/j.issn.10.11930.2015.1.142

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The high frequency switch power supply, reliable in performance, small in volume and high in efficiency, has been widely used in smart substation DC system, which guarantees the substation’s safe and reliable operation. The integrated AC/DC power system is firstly introduced, and then the DC charging module, communication power supply and UPS power supply module are analyzed respectively in detail, and the N+1 redundancy technology and current sharing technology of the high frequency switch power supply are studied specially. The result shows that application of these two kinds of technology can improve the reliability of the high frequency switch power supply module. The high frequency switch power supply can meet the requirements of intelligent substation on DC system’s reliability.

Design of an Intelligent Merging Unit with Multi-ARM Framework

ZHU Lipeng, PENG Xiaotao, YANG Jun

2015, 48(1):  146-152.  DOI: 10.11930/j.issn.10.11930.2015.1.146

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In order to reduce the facility cost of merging units and enhance their intelligence and versatility, an improved intelligent merging unit using multi-ARM for smart substations is proposed. The design procedure of its hardware and software is presented in detail. Flexible modular patterns are utilized for the whole framework design, and fiber interfaces are used to establish the bi-directional fast Ethernet communications between the system and other intelligent electronic devices. With the help of high-speed network communication, standard sampled values and GOOSE messages can be sent and received reliably based on IEC 61850. In addition, the software flows of critical modules such as sampling and switch-in/switch-out control modules are illustrated. The test results on the transmission of sampled values and GOOSE messages demonstrate that the equipment works reliably and steadily, and it shows high performances of real-time, dependability and communication speed, which greatly satisfies the needs of smart substations.

Energy Conservation and Environmental Protection

Adaptability Analysis of Activated Coke Flue Gas Purification Technology Applied in Coal Fired Power Plants

WANG Dawei

2015, 48(1):  153-156.  DOI: 10.11930/j.issn.10.11930.2015.1.153

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The adaptability of activated coke dry flue gas purification technology applied in large-scale-coal fired power plants are analyzed in combination with the pros and cons of the technology and the present status of flue gas desulphurization in domestic power plants. The key issues need to be solved in the application of the technology are discussed, such as the project costs, the adaptability to high SO2 content, the material supplies, the desulfurization byproduct disposal management and the heat resource for activated coke regeneration. The analysis also indicates that for the high sulfur coal in China, the technology needs to be further developed if applied. In particular, only the technology suitable for wide-range flue gas with independent intellectual rights is developed and the core equipiments, such as the absorber and the regenerator are manufactured domestically, can the project costs be reduced by a big margin so as to make the technology more advantageous in technical and economic performances and be applied broadly.

Experimental Study Effects of Na, K, Fe on the Denitrification Efficiency of Biomass Char in the Absence of Oxygen

YUN Duan

2015, 48(1):  157-160.  DOI: 10.11930/j.issn.10.11930.2015.1.157

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The contents of Na, K and Fe in biomass fuels are high, which is helpful to reburning denitrification adopted for low-NOx combustion. Considering the effective utilization of biomass resources in China, it is necessary to study the denitration performance of biomass char. Therefore, the effects of Na, K and Fe in the NO-char reaction are studied in the fixed-bed system. The results show that adequate Na, K and Fe can increase the reduction of NOx, and by adding these elements to the acid-washed de-ashed biomass char, the NOx removal efficiency can also be raised substantially. In addition, the denitrification efficiency of biomass char will be increased by more than 20% when 0.1 g/g Na2CO3 or K2CO3 being added, and higher increase occurs with the rising amount of Na and K The effect of Fe on biomass char denitrification efficiency is superior to that of Na and K. The denitrification efficiency can be increased by 20% when 0.01 g/g Fe(NO3)3 is added, but it will be decreased while the amount of Fe is more than 0.04 g/g.