Table of Content

18 December 2015, Volume 48 Issue 12

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Smart Grid

Research on Deployment Scheme of Power Synchronization Network Management System

XING Zechao, TENG Ling, GAO Qiang, WANG Miaoxin, WANG Yang

2015, 48(12):  1-5.  DOI: 10.11930/j.issn.1004-9649.2015.12.1.4

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In order to solve the problem of lack of unified management in power synchronous network management, some key technologies in power synchronization network management are discussed based on characteristics of telecommunication. Considering the standpoint of electric power industries, four schemes, namely third-party network central deployment, original factory network central deployment, third-party network dispersed deployment and original factory network dispersed deployment are proposed. After comparison from aspects of initial investment, operation costs and technical superiority, the third-party network central deployment is selected as the most suitable scheme for national network management. A specific application of proposed scheme in North China are also presented.

Research and Testing of Real-Time Performance of Modbus/TCP Protocol

WANG Linhao, WU Guichu, DAI Chong, ZENG Linghua

2015, 48(12):  6-6.  DOI: 10.11930/j.issn.1004-9649.2015.12.6.0

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This paper studies the real-time performance of Modbus/TCP protocol. Theoretical analysis is conducted on establishing of Modbus/TCP transportation layer and data transmission time of Modbus application frame over Ethernet. Modbus/TCP protocol is applied in low-voltage power distribution system. A testing platform using intelligent circuit breaker as a modbus slave device is built to test the real-time performance of Modbus/TCP protocol over Ethernet. Detailed analysis of transmission delay on Modbus / TCP over Ethernet and Modbus over serial link is given based on test results. It concludes that Modbus/TCP has good real-time performance and satisfies communication needs of intelligent power distribution equipments. It is an efficient solution for the network communication of low-voltage power distribution system.

Research on On-Line Monitoring Scheme of Power Time Synchronization System

LI Xin, TENG Ling, XIONG Hongzhang, GAO Qiang, LU Lifeng, WANG Yang

2015, 48(12):  12-15.  DOI: 10.11930/j.issn.1004-9649.2015.12.12.3

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In order to solve problem of lacking of control measures of time synchronization system and timed devices in substations, the applicability of relative and absolute monitoring methods are analyzed. The relative monitoring method is suitable for time synchronization system with Precision Time Protocol(PTP) signal, while absolute monitoring method is suitable for independent time synchronization systems. A time synchronization monitoring system architecture is proposed in order to transfer monitoring signal in electric power dispatching data network based on current system situation and absolute monitoring method. The proposed method uses time monitoring unit equipment to monitor timed devices status in plant, station and secondary equipment. An implementation plan of northern Hebei power grid is also presented.

Design of Intelligent Switching Order Supervising System

DONG Xiaofeng, GU Xiaowen, WANG Ye, ZHU Guofang

2015, 48(12):  16-22.  DOI: 10.11930/j.issn.1004-9649.2015.12.16.6

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After review of current operation situation, requirement and process of switching order system, a novel intelligent monitoring system is proposed. The proposed system integrates server terminals, communication network, intelligent wearable equipment and verification mechanism of computer pattern recognition. The computer acts as second remote supervisor in addition to the original one- watch-one-operate working mode, which increase operation safety and improve work efficiency. It also add record and monitoring in the switching process. It is also possible to implement single person switching operation with computer and operator remote operation, which effectively increase working efficiency and reduce operation cost.

Design and Implementation of Insulator Resistance Measurement Robot Based on WiFi Wireless Remote Control

CAI Zhengzi, LI Weiguo, CAO Wenbin, LIU Fuhao

2015, 48(12):  23-26.  DOI: 10.11930/j.issn.1004-9649.2015.12.23.3

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Insulator resistance measurement is mainly performed by human, which has low efficiency, high risk and intense workload. An insulator resistance measurement robot based on WiFi wireless remote control is designed and implemented in actual engineering project. The robot can be used to measure porcelain insulator resistance of every piece of insulator string on the overhead line. It is suitable for porcelain insulator string arranged in different angles. The whole system consists of three parts, the upper computer-tablet PC, measuring terminal and actuator robot. Engineering practice test shows safe and stable performance of the proposed method. The fast measurement can greatly improve resistance measurement efficiency.

Research on Grid Security Risk and Response Strategies on Centralized Monitoring of Massive Information

WANG Bo, WANG Wei, LI Fengwei

2015, 48(12):  27-32.  DOI: 10.11930/j.issn.1004-9649.2015.12.27.5

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Based on the centralized power grid monitoring development of the State Grid Corporation of China, the potential security risks of the power grid is elaborated in this paper. In view of the separated and centralized massive information problems, it is discussed how to establish an efficient automation support systems and formulate reasonable management strategies so as to control the potential risks and effectively response the ordeal of hazard weather and major power grid faults, and consequently make a full play of the advantages of centralized monitoring and ensure the grid safety and reliability.

The Mapping and Application of the Wind Zone Distribution of Hunan

WANG Feng, ZHOU Ting, WANG Cheng, Huang Fuyong, ZENG Peng

2015, 48(12):  33-38.  DOI: 10.11930/j.issn.1004-9649.2015.12.33.5

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Power systems are increasingly threatened by the severe wind disasters. However, the conventional standards for wind zone distribution are relatively coarse, especially in anti-wind design and refurbishment of transmission line. Currently, there are not enough guides for anti-wind design and that is the main focus of this work. Firstly, the characteristics of the faults caused by wind in Hunan power grid, one provincial power grid located in south China, are investigated in detail. By using the well-known I distribution statistical model, the meteorological data of Hunan during the past three decades are presented and discussed. The wind characteristics are summarized and the standards for wind zone distribution of Hunan are proposed. Furthermore, the suggestions for the mapping and practical applications for the wind zone distribution are presented. The work offers technical references for anti-wind design and reconstruction of transmission line.

Application of Beidou Communication in Smart Grid Status Monitoring

OU Yuqiang, ZHANG Fei, GUO Xiaolong, XU Ping, MA Chengzhi, FAN Yazhou, JIAN Wei, ZHENG Zengwen

2015, 48(12):  39-42.  DOI: 10.11930/j.issn.1004-9649.2015.12.39.3

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Power transmission line status monitoring technology is very important to Smart Grid. Currently, most systems are based on public mobile network. Those systems are subject to restriction of geographical environmental conditions and have lots of blind area. A new system architecture and technical scheme is proposed by using Beidou satellite communication. The redesigned software and hardware has ability to use Beidou satellite short message as key data transmission method for power transmission status monitoring. The proposed method can provide stable and reliable real time data transmission of power transmission line status monitoring. The system is applicable and extendable with smart grid information development.

Application of Smart Substation GOOSE Network

HUANG Zhongsheng, LIU Juan, LIAO Xiaojun, WANG Tingting, FENG Xianzheng, LIU Xinghai

2015, 48(12):  43-47.  DOI: 10.11930/j.issn.1004-9649.2015.12.43.4

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In order to ensure real-time performance and reliability of generic object oriented substation event(GOOSE) message transmission in smart substation, the characteristics of static MAC address, virtual local area network(VLAN) and GARP Multicast Registration Protocol(GMRP) for packet filtering are analyzed and compared. The port based VLAN scheme is feasible solution in smart substation communication at the present stage. The data flow and interaction range of the GOOSE packets between the intelligent electronic devices (IED) are analyzed in detail. A VLAN partition scheme based on GOOSE information classification and protection bay is proposed. A GOOSE configuration scheme is given using real project as example. The proposed scheme is easy to implement, has clear data flow and can isolate multicast packets effectively.

Research on the Integrated Design of Prefabricated Pure Electric Bus Charging Station

LI Linlin, FANG Xiangcheng, LI Songhe, SONG Bingbing, ZHANG Xiaoguang, WANG Xiaolei

2015, 48(12):  48-53.  DOI: 10.11930/j.issn.1004-9649.2015.12.48.5

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With the continuous decrease of world energy in these years, the extensive use of vehicles has led to the lack of oil reserves. The clean energy vehicles are good solution to the energy shortage and are promoted in lots of countries. However, the major problems for the electric vehicle development are the lifetime and power charging of electric vehicles. Therefore, construction of the power charging station is in the first pri-ority of the project. The existing power charging stations are constructed by building“house” firstly, followed by assembling and debugging power supply facilities, purging electric facilities, monitoring facilities and auxiliary facilities. A new type of prefab-ricated power system is proposed, in which the cabinet is used to replace the original power station building and a simple greenhouses are constructed in the field . The elec-tric and monitoring ficilities, such as lighting HVAC, water supply, drainage, firefighting and environmental protection equipment are wired and cabled in the prefabricated cabi-net. The integration design saves the resources of human, material, finance and space.

Generation Technology

Application of Steam Ejector Pump in CCHP Systems

HU Mengqi, XIAO Junfeng, ZHONG Daotong, LI Yuanyuan, LIAN Xiaolong, LI Zhaoyu

2015, 48(12):  54-58.  DOI: 10.11930/j.issn.1004-9649.2015.12.54.4

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Generally, in combined cold, heat and power(CCHP) systems, desuperheaters are used to obtain the low grade steam. However, during the pressure and temperature reduction process, irreversible energy losses are caused, lowering the steam working capability. In this study, the steam ejector pump is introduced into the CCHP system to lower the steam grade by virtue of high grade steam entrainment, forcing the high grade steam to return to the steam turbine to convert into power. As a result, the economic efficiency of the CCHP system is improved without changing the flow path of the steam turbines. The calculation and analysis indicate that when applying the steam ejector pump in the system, the generation and system efficiencies and the maximum heat supply capacity of the CCHP system increase significantly and they can meet the heat demand increase. In addition, the optimization design principles and off-design adjustment method of the steam ejector pump are valuable for the study and application of steam ejector pumps.

Optical Measurement on Particle Velocity in a Large-Scale Circulating Fluidized Bed Boiler Furnace

ZHOU Xinglong, SUN Ping, XIE Jianwen, YANG Bin, GAO Shengbin

2015, 48(12):  59-63.  DOI: 10.11930/j.issn.1004-9649.2015.12.59.4

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Distribution of particle velocity in the circulating fluidized bed boiler furnace has important influence on issues of combustion, heat transfer and abrasion. Experimental measuring holes are set on the water walls of a 330 MW circulating fluidized bed boiler furnace. A water cooled optical fiber probe is used to measure the local particle axial velocity in the furnace. Horizontal distribution of particle axial velocity near the water wall, boundary layer thickness, downward velocity of cluster and relative velocity of gas and particle are studied. Results show that negative particle axial velocity exists on the water wall. Particle axial velocity increases with the increment of distance to the water wall. Particle axial velocity is positive in the core region of furnace. The boundary layer thickness is about 0.1~0.2 m. The boundary layer thickness increases slightly with the increment of distance to the top of furnace. Downward velocity of cluster is less than 1 m/s. The relative velocity of gas and particle (about 2.05~2.73 m/s) is higher than the particle terminal velocity.

FEM Analysis of Heat Transfer Crisis of Water Wall Tube on Transverse Crack in Ultra-Supercritical Pressure Boiler

LI Bin, WANG Huajian, LIANG Xuedong, WANG Chengbin, SHI Biao

2015, 48(12):  64-69.  DOI: 10.11930/j.issn.1004-9649.2015.12.64.5

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In order to study the features of the temperature and the thermal stress distribution in water wall tubes under different conditions, the 3D FEM model of a water wall tube of a 1 000-MW ultra-supercritical pressure boiler is built and the computation is taken in the scenarios of the normal heat transfer and the deteriorated heat transfer. The computation results show that the temperature and the thermal stress are strongly affected by the fire-side heat flux and the tube internal heat transfer coefficient, and there is a linear relationship between the temperature and the thermal stress before the water wall tube yields. In the normal heat transfer scenario, the temperature and the thermal stress in fins are bigger than that in the fire-side apex, while in the deteriorated heat transfer scenario, the temperature and the thermal stress in the fire-side apex grow greatly, and they are much bigger than that in fins. The alternating stress caused by the repeated heat transfer crisis will make transversal cracks in the tube.

The Analysis of Electromagnetic Properties and Fault Handling of Magnetoresistive Rotational Speed Measuring System

WANG Zhijie, LIU Fuping, CHANG Xuenian

2015, 48(12):  70-73.  DOI: 10.11930/j.issn.1004-9649.2015.12.70.3

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The magnetic resistance speed sensor is a common device for rotational speed measurement. Regarding the faulty speed measurement due to its own electromagnetic properties of the magnetoresistive speed measuring system during generation unit commissioning, the fault analysis is conducted and the fault mechanism is also studied. The analysis reveals the variation principles of the input voltage of the measuring module with respect to its own resistance, capacitance, and alternating frequency of the electromotive force. Based on that, the specific treatment measures and proposals are put forward. The implementation of these measures exhibits the effectiveness in eliminating the measurement fault.

Design and Economic Analysis of Adjustable Ten-Stage Heat Regeneration System for 1 000-MW Ultra-Supercritical Unit

XU Hongbo, CHEN Qing

2015, 48(12):  74-78.  DOI: 10.11930/j.issn.1004-9649.2015.12.74.4

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In this paper, the in-depth study is conducted on the feasibility and economics of the adjustable ten-stage heat regeneration system for the two 1 000-MW ultra-supercritical units with one reheat cycle in Shenhua Guohua Yongzhou Power Plant (2×1 000 MW) Phase I Project. The serial No.0 high-pressure heater, equipped with the control valve to regulate the extraction pressure, is placed upstream the outer steam cooler. Under the partial load conditions, compared with the ten-stage heat regeneration system with nonadjustable stage, the initial steam pressure of the No.0 HP heater and the feedwater temperature are both improved, which lowers the turbine heat rate by 12~38 kJ/kWh, showing significant decrease of coal consumption. As a result, the total comprehensive benefit of the two units in 20 years can be as much as 53.08 million yuan.

Analysis on the Application and Related Issues of TCCS Technology in Large Nuclear Power Units

JI Runjing, ZHANG Junfeng, LIU Yang, XUE Jin

2015, 48(12):  79-84.  DOI: 10.11930/j.issn.1004-9649.2015.12.79.5

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Regarding the problem that the measured clearance value in disassembled casing condition cannot reflect the actual operation status when using the traditional method to measure the large capacity nuclear turbine clearance, this paper introduces a laser-track based clearance control technique, i.e. TCCS, which can be applied for assembled casing condition. Compared with the traditional method, the advantages and limitations of TCCS are presented. The data analysis is conducted for the first TCCS application case of domestic large capacity nuclear turbine and the problems in the application are put forward. Considering the actual situation on site, 15 action items from four aspects are proposed and carried out. Through the implementation of these action items, the problems are solved, the application of TCCS on site is improved and satisfactory result is achieved eventually.

Study and Application of NO_x Emission Reduction Technology for 1 000-MW Boilers

XU Yichun, ZHAI Deshuang

2015, 48(12):  85-90.  DOI: 10.11930/j.issn.1004-9649.2015.12.85.5

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With the stricter national standards on NO_x emissions set in China, the low NO_x combustion technology will be much more widely adopted in boiler combustion optimization. In this paper, a series of study on the closed loop control system for low NO_x combustion and the state controller of SCR spraying ammonia grille tone is conducted in consideration of the optimization of low NO_x combustion technique and SCR denitration system. In the study, the optimization strategies are proposed and the comprehensive optimization system for boiler combustion and denitration operation is developed. The engineering practice shows that, under different load conditions, by virtue of the comprehensive optimization system in practice, the denitration efficiency is improved while the NO_x emission concentration and ammonia escape rate are lowered down at the outlet of SCR reactor. In this way the national standard requirements of gas turbine emissions can be met.

The RB Control Strategies for 600-MW Supercritical CFB Power Unit

MA Rui, YANG Xuesong, ZHOU Xiyuan

2015, 48(12):  91-95.  DOI: 10.11930/j.issn.1004-9649.2015.12.91.4

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In this paper, the runback control strategies for the world’s first 600-MW supercritical CFB unit of Baima Power Plant are ananlyzed. The analysis includes post-runback control mode switching, override interlock, deviation block, limit block and parameters change-over. With these control strategies, the runback actions can be completed highly automatically and the unit can be recovered to the target load at the optimal runback rate with all the main parameters controlled within the normal operation range. Moreover, during the fan runback, by performing the interlock and override functions, the furance pressure control quality is improved; and during the feedwater pump runback, lower target load is more helpful for the steam/water system heat balance. By adopting the desuperheating control based on the physical mechanism model, the fast increase of steam temperaure can be inhibited, and by adopting the two-staged priamry air control, boiler normal fluidizing and bed pressure balance can be ensured. The runback tests show that the control quality of these strategies are good enough for popularization.

Power System

Real-Time Evaluation for Load Capability of Active Distribution Network

ZHU Jing, GAO Yajing, LIU Jianpeng, CHENG Huaxin, LIANG Haifeng, LI Peng

2015, 48(12):  96-102.  DOI: 10.11930/j.issn.1004-9649.2015.12.96.6

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This paper proposes a real-time evaluation method for power supply capacity of active distribution network with distributed generation (DG) based on the uncertainty of DG output and the cyclical change characteristics of power grid load. The method considers the situation with the access of various types of DG in distribution network and obtains the future load and DG output through prediction. The optimization model is established using the maximum load that can be supplied by distribution network as objective function and the safe operation requirements of the system as constraint conditions. Not only can a real-time evaluation of power supply capacity and power supply margin of distribution network be provided for a period of time in the future, but also can a series of power supply bottlenecks that restrict power supply capacity be given. The findings allow dispatchers to take corresponding measures in advance according to the evaluation results to ensure the safety and reliability of power grid operation. Additionally bottlenecks discovered can be reformed to explore the potential power supply capacity.

Study on the Assessment of Line Loss Levels Based on Power Grid Characteristic Differences

ZHOU Qian, SUN Zhiming, WEI Peng, AN Haiyun

2015, 48(12):  103-109.  DOI: 10.11930/j.issn.1004-9649.2015.12.103.6

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Because the active power loss level is closely related to the grid type, it is unreasonable to take the actual power loss rate as the criteria to evaluate the level of power loss of different power grids. In order to establish a scientific and rational power loss level evaluation methods, the corresponding index system is constructed by considering the factors of grid structure, parameters of device, grid operation and the structure of power consumption, et al. Mathematical models for all indices are also proposed. Based on the value of each lower level index using AHP analysis, the comprehensive evaluation value of power loss is then obtained. The obtained evaluation values and the actual line loss rates are sorted to objectively assess the regional power grid power loss levels by analyzing the sorting results. Using IEEE-14 test system as an example, the impact of the typical indices on power loss rate are analyzed. Jiangsu power grid is also tested to verify the scientificity and effectiveness of the method. The results show that the proposed typical indices can reflect the effects on regional power loss of different grid characteristics. The evaluation method proposed in this paper provides a quantitative basis to assess the level of power loss, and it can be widely used to assess the status of active power losses for provincial, municipal or prefectural power grids, which will solve the problem of loss reduction space assessment.

Broadband Modeling of Ultra High Voltage CVT Capacitor Voltage Divider

LI Xuan, ZHANG Guangyong, WANG Xiaoqi, WANG Ping, WANG Zengwen, LI Xiaoyan

2015, 48(12):  110-114.  DOI: 10.11930/j.issn.1004-9649.2015.12.110.4

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Ultra high voltage(UHV) capacitor voltage transformer(CVT) is an important primary equipment. As the capacitive divider of CVT suffers high voltage from power grid, broadband modeling of CVT capacitive divider has important significance for studying the over-voltage distribution. The broadband’s impedance parameters of the CVT capacitive voltage divider are measured by network analyzer and processed for rational function approximation with the vector matching method. And then a broadband equivalent circuit is built by circuit synthesis. Comparing the measurement and modeling results of the two devices shows that the method is applicable to broadband modeling of UHV CVT capacitive divider.

Study on “Load-Grid-Source” Coordination with Participation of Gansu Grid-Based Energy-Intensive Enterprises to Facilitate Renewable Energy Accommodation

LI Ming, YANG Lieluan, WANG Weizhou, SUN Hongbin, WANG Bin, JIN Hongyang

2015, 48(12):  115-121.  DOI: 10.11930/j.issn.1004-9649.2015.12.115.6

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With the fast construction of the renewable energy plants, the curtailment of wind and light power generation becomes increasingly frequent due to the limits of transmission, peak-load regulation and reserve capacity. To improve the integration of renewable energy, this paper focuses on the scheduling of energy-intensive enterprises (EIE). The properties of EIE model in load-side and the current operational status of EIE have been analyzed. Then the possibility that EIE participate in scheduling to improve the renewable energy integration is discussed. Based on the analysis, the paper proposes the idea and framework of “Load-Grid-Source” coordination. A modified decomposed coordinative scheduling (DCS) method is applied to solve the optimization problem. A case study is carried out by applying the method to prove the feasibility and efficiency of the method.

Study on the Intelligent AGC Initiative Coordinated Control System Based on the Online Prediction of Distributed Power Load

SHI Hui

2015, 48(12):  122-128.  DOI: 10.11930/j.issn.1004-9649.2015.12.122.6

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Based on the D5000 integrated data platform, an intelligent AGC initiative coordinated control system is proposed, which is composed of multi-modules. The main program module can, through ultra short-term synchronized forecasting of the distributed load, carry out several functions automatically, including AGC adjustable judgment, start/stop unit screening, real-time output adjustment. The auxiliary module can proceed the pre-conditionings before switching and emergency adjustment after accidents. The intelligent AGC system can automatically optimize and remotely start/stop hydropower units according to the load fluctuation, and automatically optimize the unit output of the whole grid. Besides, the AGC system can assist the dispatchers to perform pre-conditions before the equipment blackout and emergency adjustment after accident trip. The simulation case shows that the system can not only effectively improve the implementation rate of optimal short-term generation scheme and optimize the performance indicators, but also assist the power grid stabilization adjustment and reduce the labor intensity of dispatchers.

Simulation Study of Low Order Harmonic Stability for Islanded HVDC Systems

LIU Hongtao, ZHANG Yong, MEI Yong, ZHOU Yuzhi, XU Zheng

2015, 48(12):  129-135.  DOI: 10.11930/j.issn.1004-9649.2015.12.129.6

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Based on the detailed digital simulation models of Niucong and Puqiao HVDC systems, this paper studies the low order harmonic stability under islanded operation condition. Firstly, the ac parallel impedance and dc loop impedance of the HVDC systems are calculated with the test signal method. Then, the low order harmonic stability of the HVDC is roughly checked by analyzing the ac parallel impedance and dc loop impedance under low order harmonic frequencies. Finally, the low order harmonic stability is verified by time domain simulation. The result shows that under islanded operation condition, the harmonic impedance of the HVDC system is slightly influenced by the short circuit ration of the connected ac system. Additionally, the HVDC systems don`t have the low order harmonic instability problems under the concerned operation conditions.

Power Grid Diagram Automatic Mapping Algorithm for Radial Distribution Feeder

ZHOU Boxi, MENG Zhaoyong, WU Wenxuan, ZHU Yiyong, GUO Jianzhao

2015, 48(12):  136-140.  DOI: 10.11930/j.issn.1004-9649.2015.12.136.4

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Based on the CIM_SVG radial distribution feeder, an automatic mapping algorithm is designed in this paper. Firstly, the feeder branches which belong to different levels are preliminarily arranged in vertical and horizontal direction according to CIM_SVG based data. Then, a lever-to-lever trunk-branch model and corresponding branch-regional model which conform the object oriented programming (OOP) are proposed. By utilizing the proposed models, the extremely asymmetrical branches and the overlap/cross regions in the preliminary mapping are identified and eliminated. Finally, a 10 kV radial distribution feeder is taken for mapping as an example to demonstrate and validate the algorithm. The result shows that the proposed algorithm is able to draw the typical distribution network in a few seconds and can be applied to distribution network visual analysis.

Research on the Characteristics of Z-Type Slope Transmission Tower for ±800 kV UHV Lines

YU Jianwei, PAN Feng, XIE Fang, SONG Gang, WANG Yiwen

2015, 48(12):  141-147.  DOI: 10.11930/j.issn.1004-9649.2015.12.141.6

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UHVDC Transmission lines usually crosses the mountainous areas, where lighting activities are frequent and the earth shield function is poor. This paper presents a new type of tower called Z-type slope tower, which is suitable for UHVDC Transmission lines in mountainous areas. Compared with the conventional T-type tower, the slope tower has the conductor cross arms for both polar conductors arranged in step, which can reduce the distance from conductor to ground and make full use of the effective height of the tower to reduce the shielding failure trip out rate and improve the lightning withstand level of UHV DC transmission lines. An analysis is made on the linear and nonlinear internal force distribution of the tower structure by using the finite element analysis software. The economic feasibility of the Z-type slope tower is also studied through comparative analysis of the tower weight and the amount of concrete. The results show that the inner force of the Z-type slope tower is almost the same as that of the T-type tower, and the project cost is consistent. This paper provides a basis for the application of the Z-type slope tower in UHVDC transmission lines in the heavy lightning mountainous area.

Calculation Method for Gale Outage Probability of Transmission Lines

WANG Zhongyue, LIN Jikeng, HU Shijun, LIU Hui, YE Jianhua, WEI Wenhui, LIN Changnian, SUN Yihao

2015, 48(12):  148-154.  DOI: 10.11930/j.issn.1004-9649.2015.12.148.6

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Wind faults early warning and trip probability calculation has a positive significance for power system defending windage yaw flashover and transmission line outage. This paper presents a novel algorithm for calculating wind trip probability based on calculation model of windage yaw and g-h distribution model. Firstly, windage yaw angle and minimum air gap are computed according to the calculation model of windage yaw of insulator string. The linear relationship between minimum air gap and probability of windage yaw flashover is established. The calculation method for probability of transmission line outage under gale disaster is further proposed based on the g-h distribution model. Historical data of transmission lines in Anhui power grid verify the correctness and efficiency of proposed method. Establishing calculation model of windage yaw and gale distribution model are important to prevent gale outage.

Strategy and Practice of Cooperative Operation of Province and City Power Grid

TANG Wei, LIU Hui, LIU Ludeng, YANG Cheng

2015, 48(12):  154-160.  DOI: 10.11930/j.issn.1004-9649.2015.12.154.6

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In recent years multiple power grid outages are resulted from improper operation mode arrangement between province network and city network. In order to improve power grid operation safety and reliability, in-depth analysis is performed on defects existing in provincial and city power grid dispatching. The real-time operation data on different voltage levels scattered in provincial and city dispatch centers are integrated to realize automatic splicing of multiple sequence network topology model. The bottleneck points of network connection are searched automatically based on traversal algorithm. The loss of load is evaluated precisely in order to identify high-risk customer delivery quickly. Joint analysis is also performed on power grid real time operation control strategy. A collaborative grid model is built to identify unreasonable overlapping maintenance schedule. The realization of joint decision making of provincial and city power grid is crucial for construction of inter-provincial power network collaborative decision making platform. The practical application in provincial grid system shows that the proposed strategy can effectively avoid operating mode conflict between provincial and city grid. It also implements the collaborative decision-making on the whole grid.

Design of 110 kV CD Superconducting Cable Conductor

WU Peng

2015, 48(12):  161-165.  DOI: 10.11930/j.issn.1004-9649.2015.12.161.4

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In recent years, superconducting technology has become the major foundational innovation in modern industry development. It has important strategic significance for the present and future development. Various aspects of structural design of 110 kV/3 kA CD superconducting cable are discussed, including electromagnetic characteristic, cable materials, insulation thickness, shielding layers diameter and winding range. The results provide useful references for theoretical research and engineering practice of cable structure design in the 110 kV/3 kA CD superconducting project.

New Energy

Research and Application of Renewable Energy Accommodation Capability Evaluation Based on Time Series Production Simulation

DONG Cun, LI Mingjie, FAN Gaofeng, HUANG Yuehui, LI Xiaofei

2015, 48(12):  166-172.  DOI: 10.11930/j.issn.1004-9649.2015.12.166.6

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With the rapid development of wind power and PV power in China, it is big challenge for grid operation to reduce wind or PV power curtailment and to increase capacity for renewable energy. Annual renewable energy accommodation capability is the key point to optimize power system operation arrangement and to obligate renewable energy electricity space. After review of current research situation, a new method is proposed for annual renewable energy accommodation capability assessment based on time series production simulation. A mixed integer programming model for the constraint of starting and stopping of the generation unit is also established. Renewable Energy Production Simulation (REPS) Platform is developed based on proposed algorithm. The annual renewable energy accommodation capability of 2015 is evaluated by REPS and the comparison with field data in first quarter shows the accuracy and adaptability of proposed method.

Simulation on Fault Diagnosis of Brush and Slip Ring System in Doubly-Fed Induction Generators Based on Temperature Field

CHEN Taotao, MA Hongzhong

2015, 48(12):  173-178.  DOI: 10.11930/j.issn.1004-9649.2015.12.173.5

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A temperature field model of brush and slip ring system in doubly-fed induction generator is established in this paper by using the ANSYS software based on the principle of thermoelectric coupling. The temperature field of brush and slip ring system is calculated with the finite element method under normal operating condition, and the temperature field and current density vector distribution of the various components in the system are obtained in the paper. Then, the uneven distribution fault of brush current is simulated by loading different currents onto different brushes, and a transient simulation analysis is carried out on the brush and slip ring system under fault state. The temperature field and electric field under fault condition are compared with that under normal condition. Finally, relevant conclusions are given, which can guide the state monitoring of the temperature field and overheating fault forecast of the brush and slip ring system.

Analysis on the Measures and Actions of Germany Power System Operators during Solar Eclipse

WANG Caixia, ZHENG Zhanghua

2015, 48(12):  179-183.  DOI: 10.11930/j.issn.1004-9649.2015.12.179.4

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This paper analyzes the safty operation conditions during the solar eclipse happened in Germany on March 20^th 2015. Based on the operational data, an analysis is made on the measures taken by the German power system operators to deal with the impact of solar eclipse on power system operation. The results show that accurate solar generation forecast is an important precondition for preventing power grid from operational risks brought about by variable generations. Besides, plentiful dispatchable generation resources such as coal fired generation, power grid interconnection are the basis for assuring system opeartion security with high penetrations of variable generations. Good electricity market design is also an important way to reduce the risks brought about by variable generations.

Technology and Economics

Analysis on the Reliability Management-Control Efficiency for Power Supply Enterprises

ZHANG Yue, FU Cong, ZHAO Yanjun, WANG Longjun, HUANG Jiajian

2015, 48(12):  184-189.  DOI: 10.11930/j.issn.1004-9649.2015.12.184.5

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Analysis of the reliability management-control efficiency can not only help power supply enterprises explore the weaknesses in reliability management and control, and direct the planning, operation and maintenance of power grid according to the local conditions, but also be of great significance for steady improving the reliability level and the economic and social benefits. On the basis of analyzing the relationship between the reliability indices and the management-control indices, a two-stage approach is proposed for analyzing the management-control efficiency of power supply enterprises, which can quantify the reliability management-h efficiency of power supply enterprises, and analyze the influencing factors and their impact extent. The proposed method is implemented to 19 power supply enterprises that are under the jurisdiction of Guangdong power grid corporation, and the practical results shows that the approach is validated.

Research on the Development Model of Replacing Coal with Electricity and its Application

JIA Dexiang, HAN Jing, HUA Zhang

2015, 48(12):  190-192.  DOI: 10.11930/j.issn.1004-9649.2015.12.190.2

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Large quantity of coal has been consumed directly in China for a long time, which is an important factor for environmental pollution. With the goal of minimal total annual cost, an optimization model for replacing coal with electricity is proposed, with the reduction of coal consumption and the production capacity of the main coal replacement technology as constraints, and with consideration of China’s total coal consumption control target and the action plan of energy conservation and emission reduction. Research result shows that the market prospect of replacing coal with electricity is promising, but it needs the support of national policy for a win-win situation of every participator. A case study has proved the feasibility and efficiency of the proposed method. The method can be referred for long term planning of national coal replacement.