Table of Content

20 December 2016, Volume 49 Issue 12

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Special Contribution

Progress of Supercritical and Ultra-Supercritical Circulating Fluidized Bed Boiler Technology

CAI Runxia, LU Junfu, LING Wen, YANG Hairui, ZHANG Man, YUE Guangxi

2016, 49(12):  1-7.  DOI: 10.11930/j.issn.1004-9649.2016.12.001.07

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The supercritical and ultra-supercritical circulating fluidized bed (CFB) combustion technology combines the advantages of CFB combustion and supercritical/ultra-supercritical steam cycle, which can achieve low cost and high efficient clean coal combustion, and will be one of the most important development trends of CFB combustion technology. In this paper, the design and operation characteristics of supercritical CFB boilers are compared, including the boilers of 460 MW in Poland, 330 MW in Russia, and 600 MW and 350 MW in China. Also the update progress of ultra-supercritical CFB boilers is introduced, including the ones of 550 MW in South Korea and 660 MW in China.

Power System

Corrosion Behavior of Transmission Tower Weathering Steel under Different Atmospheric Conditions

GE Zhaojun, ZHANG Qiang, HUANG Yao, HAN Junke

2016, 49(12):  8-14.  DOI: 10.11930/j.issn.1004-9649.2016.12.008.07

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For application of weathering steel in transmission tower, a type of high strength and high toughness weathering steel is successfully developed for transmission towers, which has excellent mechanical properties with a yield strength of up to 510 MPa, a tensile strength of 568 MPa, a total elongation of greater than 27.5%, and the impact energy of 89 J~176 J under the low temperature of minus 40 ℃. The corrosion resistance of transmission tower weathering steel is evaluated comprehensively in four different atmospheric conditions by using SEM, XRD, EIS and other means. The corrosion behavior and mechanism of weathering steel in different atmospheric environments are studied. The results show that the rust resistance of transmission tower weathering steel increases gradually with increasing exposure duration. The rust corrosion product is mainly composed of α-FeOOH, γ-FeOOH, Fe3O4 and some amorphous corrosion products. Comparing with other weathering steels, the weathering steel used in Hebei Caofeidian region is most stable in protective rust layer. The transmission tower weathering steel is suitable for using in Hebei Caofeidian, Beijing Liangxiang and Fujian Yongtai regions, but temporarily not for Fujian Pingtan area.

Short-term Reliability Assessment Scheme for Distribution System

DONG Lei, ZHAO Can, CHEN Naishi, PU Tianjiao, PANG Xiaojin

2016, 49(12):  15-20.  DOI: 10.11930/j.issn.1004-9649.2016.12.015.06

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The majority of the existing reliability assessments of distribution system are for long-term average reliability. The reliability assessment for short-term or online operation is rare. Considering the characteristics and short-term conditions of elements in distribution system, this paper proposes a short-term reliability assessment scheme for distribution system, which adds the load loss conditions to define short-term reliability indices of distribution system, and uses the improved conditions dependent element model to obtain short-term outage rates, and the forward failure diffusion algorithm to evaluate and analyze the short-term reliability of the distribution system. Through simulation analysis, the feasibility of the short-term reliability indices and the effectiveness of short-term reliability model are confirmed, which may provide a theoretical basis and dispatching guidance for short-term operations of distribution systems.

Simulation of Closed Loop Current for Low Voltage Power Distribution Network Based on PSCAD/EMTDC

LI Peng, LI Huisheng, WANG Rui, FANG Binghua, CHEN Lidan

2016, 49(12):  21-25.  DOI: 10.11930/j.issn.1004-9649.2016.12.021.05

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With increasing power supply reliability requirement, low voltage distribution network will be an important factor in the future of power supply reliability and security constraints. Three power supply schemes, bus connection mode for double public transformer room, neighborhood distribution transformer and connection between two main cables from different distribution transformer, are designed. Simulation model of closed loop operation for low voltage is established by using PSCAD/EMTDC. Parameters of superior power, low voltage distribution transformers and load are changed to obtain closed loop current in different cases. Various factors related to closed loop current are analyzed. It is found that voltage phase difference between both sides has great influence on the current loop. Loads can be switched by loop closing operation when all the equipments and lines on the loop are not overloaded and closed loop impulse current is not exceeding auto-boot current value of quick-break protection.

Study on the NES6131 Detection and Alarming Device for Rotating Bridge Rectifiers

ZHANG Yin, WAN Xing, YU Zhen, LI Jianqiu, SI Chao

2016, 49(12):  26-30.  DOI: 10.11930/j.issn.1004-9649.2016.12.026.05

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Rotating bridge rectifier is the integral part of the power unit, the quality and running status of which is very important for the safe and stable operation of generator units. However, there is no proven detection and alarming device for rotary rectifying element in the domestic market. In this paper, an introduction is made to the NES6131 rotating rectifier element detection and alarm device newly developed by NARI TECH. Through a series of field tests in the No.2 generator units of Tianwan Nuclear Power Plant, the NES6131 is fully functional, reliable, accurate and high portable, and is especially suitable for large brushless generators which is equipped with position detection coil and current detection coil.

Formation Pattern and Effect of Copper Sulfide in Transformer Oil

HE Zhiman, WANG Jianfei

2016, 49(12):  31-36.  DOI: 10.11930/j.issn.1004-9649.2016.12.031.06

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The corrosive sulfur in transformer oil may cause bad impacts on the transformer insulation. In order to study the influence of corrosive sulfur in transformer oil on the copper line and the oil immersed insulation paper, a series of thermal aging tests are carried out on Oil Samples 1 and 2 at 130 ℃ and 150 ℃ in laboratory. By analyzing the property changes of bared copper line, paper wrapped copper line, paper and oil, Sample 1 exhibits strong sulfur corrosiveness while Sample 2 does not. In addition, the corrosion on the copper line surface and the insulating paper inner surface deteriorates with the aging time. The Cu2S deposition on the insulating paper is related to not only the severity of corrosion, but also the aging time. Moreover, it may change the copper line surface structure and the insulation paper fiber distribution significantly, as well as the dielectric properties of oil immersed paper. With Cu2S deposition, the breakdown field of a strong composite medium will also decrease substantially. The study results on corresponding corrosion preventive measures will be elaborated separately.

Power Grid Automatic Intelligent Dispatching Model Improvement Based on Situational Awareness

HUANG Chao, YAO Senjing, ZHU Zhengguo, DENG Kun, WEI Enwei

2016, 49(12):  37-41.  DOI: 10.11930/j.issn.1004-9649.2016.12.037.05

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Traditional power grid dispatching model is based on real-time network parameters. It lacks situational awareness of whole grid operation. The dispatching model is improved based on situational awareness theory. The awareness process is analyzed and system operation performance index are established. Based on improved model, unit dispatching process under different load are analyzed in detail. Dynamic unit commitment method is applied in intelligent automatic dispatching. The experimental results show that proposed model improvement has high efficiency and low energy consumption.

TA Saturation Detection Algorithm Based on Histogram Symmetry Correlation

WANG Yu’en, GAO Changpei, BAI Jialin, NIU Jing, ZHAO Wuzhi, ZHAO Jianxin, HUANG Ting, MA Yulong

2016, 49(12):  42-47.  DOI: 10.11930/j.issn.1004-9649.2016.12.042.06

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Current transformer (TA) saturation is a physical phenomenon which could lead to protective relay malfunction. A TA saturation detection method using frequency distribution histograms combining symmetry correlation is proposed. First of all, TA secondary current is sampled and analyzed, and then wave conversion is transformed by using waveform image transformation technology. Then, correlation degree of symmetry is calculated with generated histogram. Finally, the correlation degree is compared with setting value to determine whether current transformer saturation occurs or not. Proposed algorithm is simple, reliable, accurate and fast. It has important reference value for detecting TA saturation, improving the reliability of action and maintaining system operation.

Selection of P Type Current Transformer Based on Protection Characteristic

BAI Jialin, GAO Changpei, WANG Yu’en, ZHAO Wuzhi, NIU Jing

2016, 49(12):  48-52.  DOI: 10.11930/j.issn.1004-9649.2016.12.048.05

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In order to investigate the saturation characteristic of class P current transformer and formulate measures to prevent protection malfunction caused by transformer saturation, the impacts on current transformer transient saturation characteristic of core remanence, fault current non-periodic component, time constant and other factors are analyzed in detail through theoretical derivation and calculation. The analysis results show that current selection provisions of specified transient factor not less than 2 for protection current transformer cannot meet the line protection and transformer protection requirements. According to analysis results, advice is proposed on protection class P current transformer selection for the technical requirements of different protection devices. Considering actual situation of power network, preventive measures are also proposed from the aspects of current transformer, protection device and power grid operation.

Single Line Diagram Layout and Optimization Method for Regional Distribution System Based on Genetic Algorithm

GE Chengyu, ZHOU Boxi, ZHU Songyi, ZHANG Junling, SUN Lianxi, WANG Jinliang, ZHANG Hao,LIU Shuge, HAN Xianhe

2016, 49(12):  53-57.  DOI: 10.11930/j.issn.1004-9649.2016.12.053.05

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A GA-based single line diagram layout and optimization method for regional distribution system is proposed in this paper. The proposed method takes the minimum difference between line nodes and path as the objective function, in which the relative geographic information of substations is adopted as the constraint. With well designed crossover operator and mutation operator, the GA algorithm can be utilized to seek the optimum of nodes layout positions. While drawing the connection of line, a series of strategies are used, which include line path exploration, cross and overlap region identification and layout adjustment. The simulation results show that the algorithm allows uniform distribution of nodes in the figure. The connection line is clean and clear, and the computational efficiency and graphic effects can satisfy practical project requirements.

Coordinated Voltage Control Based on Model Prediction in Active Distribution Networks

ZHUANG Huimin, ZHANG Jianglin

2016, 49(12):  58-64.  DOI: 10.11930/j.issn.1004-9649.2016.12.058.07

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Temporary over/under voltages often occur in active distribution networks due to distributed generation, the renewable energy in particular, it is therefore necessary to control the undesirable voltage by reasonable control strategy. This paper presents a coordinated voltage control method based on model prediction by considering the intermittence of RES output and the actual action characteristics of on-load tap changer(OLTC). The trust region method with good global convergence is used for optimization. The control strategy not only can compensate the modeling inaccuracies caused by measurement error but also can predict the impact of future OLTC actions on the controlled voltages as to avoid the premature or unnecessary dispatch of other control actions. Finally, the proposed coordinated voltage control method has been tested in a 24.9 kV IEEE distribution network, which consists of 34 nodes and 5 distributed generating units. The test results show that the strategy is robust and effective for controlling voltage in active distribution networks.

Research on Optimization Measures of DC Line Recovery Sequence Logic in Tian-Guang HVDC Project

CHEN Jisheng, HUANG Yilong,WU Jianying, LI Jinwei

2016, 49(12):  65-69.  DOI: 10.11930/j.issn.1004-9649.2016.12.065.05

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Continuous faults in a short perid lead to malfunction of of Tian-Guang DC line fault restart device. Based on principles of DC line protection, protection sequence of events and line restart logic, failure reasons in second DC line fault restart are analyzed. Simulation test reproduces field fault. It is shown that if there is a second fault occurs during the 50 ms time delay of retart counter after first fault, the fault restart device will fail. Optimization measure is proposed to delete the time delay in the process. Simulation result proves feasibility and effectiveness of proposed method.

Scheme for Secondary Devices with Incomplete Power Shutoff of 220 kV Smart Substation

DING Xuanwen, LIU Mingzhong, JIANG Zhenchao, ZHENG Yongkang, LIU Xuewen

2016, 49(12):  70-75.  DOI: 10.11930/j.issn.1004-9649.2016.12.070.06

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At present, there are numbers of substandard secondary intelligent devices operating in the smart substation, which are potentially risky. It is necessary to replace, rectify and debug such substandard devices. In order to prevent the security risks that may occur in the process of renovation. A study is made on the secondary device renovation scheme with incomplete shutoff of 220 kV smart substations. The proposed scheme includes rotatory power shutoff of different bays for merging unit renovation, debugging methods for such secondary smart devices as intelligent terminals, and the secondary security measures. The scheme formulates one-on-one dual security measures according to the security risks in the process of renovating different intervals. The scheme is characterized with high security and strong operability, and has been successfully implemented in the intelligent equipment renovation of Lu Ping substation.

Research and Implementation of Regional Automatic Transfer Switching Technology Based on Real-Time Information

JIN Zhen, DONG Kaida, CHEN Jun, ZHANG Chunhe

2016, 49(12):  76-80.  DOI: 10.11930/j.issn.1004-9649.2016.12.076.05

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The paper aims at solving the problem that the fast power recovery cannot be achieved by traditional automatic transfer switching devices when a failure occurs in an 110 kV chainlike serial power supply system. Based on regional power grid real-time information, a new solution of regional automatic transfer switching is proposed in the paper, which is applicable to traditional or smart substations. A detail discussion is made on the principle and realization of regional automatic transfer switching, as well as the relationship with substation-area automatic transfer switching, traditional automatic transfer switching devices, regional relay, and regional stability control. The RTDs test and the field project application cases provide convictive results that the regional automatic transfer switching can provide a superior performance for fast power recovery when a failure occurs in regional power grid.

Generation Technology

Research and Application of Online Monitoring Model of Coal-Fired Units in the Coordinated Interaction of Large Power Grid

SUN Shuanzhu, JIANG Yefeng, DAI Jiayuan, ZHOU Ting, ZHOU Chunlei

2016, 49(12):  81-85.  DOI: 10.11930/j.issn.1004-9649.2016.12.081.05

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To avoid the impact of UHV faults on the receiving end power grid and effectively enhance the response ability of the local power resources, the study on the adjustable output online monitoring model is carried out based on the concept of power grid coordination. The model assesses the adjustable power output margin of the main coal-fired units in the aspects of the heating unit, the main auxiliary equipment running state, and the coal quality. This model tends to help the electric power dispatching department for decision making on dealing with extra high voltage failures. The model has been put into trial operation in Jiangsu power grid and been dynamically evaluating the adjustable output of more than 130 units in the province, providing real-time and reliable online monitoring and evaluation results.

Quantitative Analysis on Influence of Boiler Heat Storage Coefficient on Coordinated Control System Parameters

CHEN Qi, GUO Xiaohong, WANG Biao, XIN Xiaogang

2016, 49(12):  86-90.  DOI: 10.11930/j.issn.1004-9649.2016.12.086.05

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The boiler heat storage coefficient is the parameter which affects the coordinated control system, especially the controller on the boiler side in thermal power plants. Based on the values of different operation conditions calculated with the design and operation data, the heat storage coefficient is simplified linearly according to the simplified nonlinear dynamic model. After the linearization, the transfer function of boiler fuel flow versus throttle pressure is deduced for the simplified typical boiler-following-turbine coordinated control system structure under the condition of the generation loads controlled by HP cylinder regulating valve opening. The study results show that the boiler-side equivalent controlled object is the non-self-balanced object with integral characteristic, and the boiler heat storage coefficient is reflected in the object gain. The rule is that the bigger the heat storage coefficient is, the smaller the object gain will be. According to this rule, the gain compensation logic for the coordinated control system of a 600-MW unit is designed, which has obtained satisfying control performance in the load range of 50%~100%.

The Mechanism and Restraining Measures for Low Frequency Oscillations with Participating Steam Turbine Units in Power System

ZHANG Bao, FAN Yinlong, GU Zhenghao, WU Wenjian

2016, 49(12):  91-95.  DOI: 10.11930/j.issn.1004-9649.2016.12.091.05

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The steam turbine unit is closely related to the power system low frequency oscillation. The classification, mechanism and locating methods for power system low frequency oscillations are presented in details from the aspect of the steam turbine unit. Then, specific measures to restrain the low frequency oscillation are proposed from the power generation side in terms of control logic optimization, strict testing as well as quick and correct operation procedures. At last, suggestions on power grid coordination are put forward, such as the control logic optimization and strict field testing, to improve the power grid security and stability level.

R&D and Application of Plant-Wide Load Control System for Thermal Power Plants

NIU Honghai, LI Bing, CHEN Jun

2016, 49(12):  96-100.  DOI: 10.11930/j.issn.1004-9649.2016.12.096.05

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To solve the problem that the current AGC mode cannot guarantee the economic and safe operation of the power plant simultaneously, the current development and the applications of the plant-wide load control system are analyzed, and the study on the key technologies such as the system architecture and the plant-wide optimal load distribution model is conducted in this paper. First, one dual redundant plant-wide load control system based on the embedded device is proposed, which can not only meet the security and real-time requirements of the power grid, but also realize high information integration of the plant. Then, based on the traditional plant-wide load distribution model that fulfills the minimum coal consumption rate, a new online multi-objective load optimal distribution model is established with the consideration of the frequency regulation requirements. The simulation results show that with the model, the average gross coal consumption rate can be reduced by about 0.3 g/(kW·h). At the end, the main functions of the plant-wide load control system are introduced, which could provide reference for the implementation and reconstruction of the system.

Infornation and Communication

Construction and Application of State Grid Enterprise Information Architecture Model SG-EA

WANG Jiye, GAO Lingchao, HAO Hanyong , ZHENG Lei

2016, 49(12):  101-106.  DOI: 10.11930/j.issn.1004-9649.2016.12.101.06

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The enterprise information system is becoming increasingly complicated. A method based on the enterprise architecture design is proposed in this paper to construct and apply the enterprise architecture model for information from the global perspective. The paper discusses the method’s theoretical basis, construction process, application scenarios and application results. The method not only makes the information system and the service consistency analysis more standard and automatic, but also makes it easier to construct a steady enterprise architecture of information system so as to realize the matching of enterprise’s IT strategy and business strategy, data sharing, module integration, business collaboration, and meet the business requirement for future development.

Research on Intelligence Management Mode of Power Cables with Internet Plus

WANG Chunlin, WANG Hui, WEN Rui, XIANG Yong

2016, 49(12):  107-113.  DOI: 10.11930/j.issn.1004-9649.2016.12.107.07

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With the advancement of urbanization, power cables are widely applied in city power supply grid. In this paper, the challenge of current management mode of cable lines is analyzed, and then the intelligence management mode is proposed. Finally, Based on a case study of the cable management of Suzhou city grid, an introduction is made to the advancement of the intelligence management mode of power cables in China.

Analysis on IPv6 and Its Application in Electric Power Automation Systems

GAO Zhiyuan, WANG Wei, SUN Qian, YAN Mifang, CAO Yang, ZHANG Jing

2016, 49(12):  114-120.  DOI: 10.11930/j.issn.1004-9649.2016.12.114.07

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IP protocol of network layer is developing from IPv4 to IPv6, which has important impacts on the realization of electric power automation systems. It is necessary to systematically analyze the impacts of IPv6 on power system automation and its possible application scenarios. Based on protocol changes from IPv4 to IPv6, changes of technology characteristics are described. Application prospects in electric power automation systems in accordance of IPv6 technology improvements are then discussed. Furthermore, in-depth analyses of important possible application scenarios are provided. Electric power automation systems have wide range of potential demands for IPv6 protocol, especially in the scenarios that need large number of globally-routable Internet addresses, better end-to-end communication abilities or better QoS control abilities. However, practical application implementations of IPv6 depend on project requirement and specific technical conditions in different scenarios.

Research on Adaptability of Distribution Communication Network in Typical Application Scenarios

HU Qianqian, ZHAO Honghao, DU Chunchao, HU Yang, CHEN Ze

2016, 49(12):  121-126.  DOI: 10.11930/j.issn.1004-9649.2016.12.121.06

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To address the unified planning and design issues of distribution network communication system with different scenarios, this paper analyzes the traffic flow of network communication system with different sizes in different application scenarios based on the distribution network model. The main communication networking technologies used in the power terminal communication access network are discussed, and based on the flow analysis, the adaptabilities of different communication modes to the distribution network are compared from the perspectives of network availability and resource utilization. The results show that in the power supply region of class A+, A and B where the distribution automation business is operated, both the optical fiber communication technology and dedicated wireless network can be adapted; while in the region not capable for laying fiber cable, the dedicated wireless network technology should be the first choice.

New Energy

A Short-Term Wind Power Prediction Method of Multiple Output Model

YANG Mao, DONG Juncheng

2016, 49(12):  127-132.  DOI: 10.11930/j.issn.1004-9649.2016.12.127.06

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Accurate wind power prediction is important for power system planning and operation. Based on extensive wind power historical data, a new short-term prediction method of multiple output model is proposed by combing correlation analysis and K-Nearest Neighbor algorithm. Taken field measurement data from two wind farms in Northeast region as example, the two multi-step prediction methods are evaluated by using index defined by National Energy Board. The results show high precision and simplicity of proposed method.

A Combined Photovoltaic Output Forecasting Method Based on Rough Set Theory

YANG Xiyun, REN Jie, XIAO Yunqi

2016, 49(12):  133-138.  DOI: 10.11930/j.issn.1004-9649.2016.12.133.06

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Photovoltaic output prediction is an effective way to decrease impacts for photovoltaic power connecting to grid. Improving accuracy is the key to photovoltaic output prediction. A combined prediction method is proposed based on rough set theory. Firstly, three different models, namely, similar day method, support vector machine and persistence method, are constructed. Then rough set theory is used to obtain relative weights by calculating degree of importance. Finally, the combined model is established by using the weights obtained. A case study shows that rough set theory is effective to obtain appropriate weights, which lead to high prediction accuracy of proposed method.

Technical Performance Test and Improvement Measure Study for Dynamic Reactive Compensation Devices Applied in Large-Scale Wind Power System

LIU Jingbo, CUI Zhengpai, WU Yuhui, LIU Hui

2016, 49(12):  139-143.  DOI: 10.11930/j.issn.1004-9649.2016.12.139.05

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The voltage stability problem of large-scale wind power collection system is key factor to power grids. Dynamic reactive power compensation devices on wind farms are effective for controlling reactive power and voltage of wind power system. However, in field operation process, reactive power compensation device has problems including unreliable operation, slow dynamic response time which does not meet power grid requirement. Some effective correction measures are proposed based on testing results. Practice shows that reactive power compensation device performance testing and rectification work can effectively improve device performance, system operation safety and wind power accommodation capability.

A Dynamic Equivalence Method Considering the Effect of Spatial Wind Farms

YUAN You, KANG Jitao, WANG Delin, XU Mingyu, GAO Chaofeng

2016, 49(12):  144-149.  DOI: 10.11930/j.issn.1004-9649.2016.11.144.06

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A dynamic equivalent model suitable for wind farms based on clustering algorithms and experimental data is presented in this paper. According to the experimental data of one wind farm, Existence of dispersion between wind farm units is proved by the way of comparison of random sampling. Besides, the study making use of the significant difference between wind speed curves and power curves in different units indicates that the dispersion among wind farm units can’t be ignored. In the new model, the wind farms ′33 UP77-1.5MW wind turbine units are clustered into four categories by making use of the K-means cluster analysis of SPSS platform and using the measured data as clustering index. At last, the macro comparison and error analysis between various models and measured data verifies the rationality of the model. In addition, the result of comparing with the traditional model indicates that the model in the new method of this paper has a higher accuracy.

Calculation Method of Power Supply Capacity of Distribution Network Considering Distributed PV

YANG Fenyan, ZHANG Yue, ZENG Jie, ZOU Guangyu

2016, 49(12):  150-155.  DOI: 10.11930/j.issn.1004-9649.2016.12.150.06

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Power supply capacity can be improved by integration of distributed PV. A calculation method is presented in this paper to effectively calculate the power supply capacity of distribution network with consideration of distributed photovoltaic(PV). Firstly, the distributed PV is simplified into one special transformer and the analysis of power supply capacity is thus dumbed down. Then, the Monte Carlo simulation is used to estimate the reliability of the combined system of distributed PV and traditional transformers. Finally, the power supply capacity is calculated through checking the procedure of“N-1” standard. Case study has shown that the proposed method can calculate the effectiveness of the distributed PV in improving power supply capacity.

Technology and Economics

Post-Evaluation of Economic Benefits of Power Grid Projects with Consideration of Relevance

WU Yunna, FAN Liang, CHEN Kaifeng

2016, 49(12):  156-161.  DOI: 10.11930/j.issn.1004-9649.2016.12.156.06

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In the context of electric power system reform, power supply companies have to estimate the economic performance of the constructed power grid projects with a more market-oriented perspective so as to provide a support for management decision-making of similar construction projects. An economic benefits post-evaluation model is proposed for power grid projects and an index system with network hierarchy is built which consists of such four relevant factors as construction costs, financial benefit, social benefit, economic benefit and environmental impact costs. The ANP method is applied to solve the weight of relevant index, and the hesitant language evaluation method is introduced to serve the policymakers. Finally, the cloud model is used to assemble every index evaluation result. Three power grid construction projects built in Liaoning province are used to verify the feasibility and rationality of the proposed model.

Research on Pricing Mechanism of West-to-East Power Transmission Price for China Southern Power Grid

LI Feng, YU Chao, KONG LIANG, LIU Qing, ZHANG Jian, LV Shisen

2016, 49(12):  162-167.  DOI: 10.11930/j.issn.1004-9649.2016.12.162.06

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West-to-east power transmission is of strategic significance for speeding up China’s energy structure adjustment and promoting the economic development and optimal allocation of resources of the western regions. Along with the gradual rise of the power price level, the problems of west-to-east power transmission are getting prominent. A study is made on the pricing mechanism of west-to-east power transmission during the “13th Five-Year” priod (2016-2020) in terms of stock and increment. A two-part transmission pricing mechanism of the incremental part is proposed based on the hierarchical power transmission curve, and the ratio between of the electrical capacity charge and power charge is determined, and the electrical capacity charge is apportioned with peak-load electricity capacity ratio method. An analysis is made on the impact of the two-part transmission pricing mechanism on the interests of power feeding and receiving ends as well as transmission companies. And the interests of the shareholders are also discussed respectively under guarantee curve, protocol curve and super delivery curve. It is concluded that the proposed two-part transmission pricing mechanism under the hierarchical electricity curve can stabilize the income level of transmission companies, and encourage the enthusiasm of both the feeding-end and the receiving-end respectively for increasing the generation capacity and receiving the western power. The proposed idea can be an important reference for solving the west-to-east power transmission pricing problems.

Energy Conservation and Environmental Protection

Review of SO2 and H2O Poisoning over Commercial Vanadium-Titanium Catalysts in the Selective Catalytic Reduction Denitration

YU Yuexi, LIAO Yongjin, SHU Han, SHI Yajuan, ZHANG Yaping, YANG Linjun

2016, 49(12):  168-173.  DOI: 10.11930/j.issn.1004-9649.2016.12.168.06

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So far the technology of selective catalytic reduction of NOx with NH3 has been widely applied in power plants, of which the hot topics such as the effect of flue gas composition on catalyst performance, catalyst poisoning and the production of fine particles have been drawing more attentions. In this review the discussion is focused on the poisoning mechanism, influencing factors and optimization measures of SO2 and H2O in flue gas on the commercial V2O5-WO3/TiO2 catalysts. The poisoning mechanism of SO2 mainly includes ammonium sulfates blocking, mental sulfate absorbed on the active sites and the competitive absorption with NH3 and NO. The poisoning mechanism of H2O refers to the deteriorating NOx removal efficiency of the catalyst due to the competitive adsorption with NH3 and NO, which promotes the production of ammonium sulfate and inhibits the reaction between ammonium sulfates and NO, etc.

Numerical Simulation of Desulfurization Wastewater Treatment with in-Depth Filtration-Flue Evaporation Process

JIN Yinjia, WANG Shuai, JI Haihong, WANG Fengji, ZHU Yue, WANG Shuo

2016, 49(12):  174-179.  DOI: 10.11930/j.issn.1004-9649.2016.12.174.06

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The atomizing nozzle of the desulfurization wastewater treatment system tends to be blocked by the suspended solids in the water. Therefore, the correlative filtration process is proposed as a pretreatment process, in which the water is thoroughly separated before evaporation. After the filtration, the mass concentration of the suspended solids in the wastewater can be decreased to 40 mg/L with over 99% of the remaining particles smaller than 1 μm. Moreover, the theoretical calculation as well as digital simulation using the Fluent software package is conducted to study the evaporation process. The results show that higher flue gas temperature and smaller liquid drop diameter yield shorter evaporation time. By taking in account of the liquid drop evaporation effects and the energy consumption, it is recommended to make the diameter of the liquid drops under 60 μm in engineering applications. The study results can provide some guidance for the atomizing nozzle system design, as well as the optimization of the treatment process.

Numerical Study on the Installation of V-Shaped Guide Plate behind theAmmonia Injection Grid

ZHANG Ling, LIU Haiting

2016, 49(12):  180-184.  DOI: 10.11930/j.issn.1004-9649.2016.12.180.05

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The mixture evenness of ammonia and flue gas has great impacts on both the denitrification efficiency and the ammonia slip. By taking the example of the selective catalytic reduction (SCR) flue gas denitrification system of a 600-MW coal-fired power plant as the study case, the Fluent software is used to calculate the air mixture flow rate at various flue gas velocities with no spoiler and the ammonia-air mixture flow rate at 0.5 and 0.8 m/s respectively. The optimal flow rate combination is obtained as flue gas velocity of 3.7 m/s and ammonia-air mixture flow rate of 0.5 m/s. Then, the V-shaped spoiler(horizontally or vertically arranged) is installed behind the ammonia injection grid to make the ammonia mixed evenly with the flue gas. Numerical simulation is conducted on velocity, flow field uniformity, pressure and pressure drop. From the simulation results the horizontal V-shaped spoiler exhibits satisfactory performance in mixing the ammonia evenly with the flue gas so as to meet the designed requirements of system pressure drop.