Table of Content

16 June 2016, Volume 49 Issue 6

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Column of Instrument & Control

Design and Implementation of Intelligent Control Function Module for Air and Flue Gas System of Thermal Power Units

ZHU Xiaoxing, CHEN Houtao, CHANG Xuenian, JIANG Sennian, CHEN Siming

2016, 49(6):  1-5.  DOI: 10.11930/j.issn.1004-9649.2016.06.001.05

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The air and flue gas system is an indispensable part of thermal power units. To improve the intelligence level of the thermal power units, the requirements on the intelligent control function module for the air and flue gas system is analyzed, and the functional groups consisting of intelligent startup, operation and shutdown as well as other functional subgroups are designed. Modular design is adopted for each functional group and subgroup , which could be adapted to various operating conditions, such as normal, maintenance, or failure conditions. Manual control is set to be higher priority in case of an emergency. The simulation and application results show that without any manual intervention, by utilizing the intelligent control function module the entire process of startup, operation and shutdown of the air and flue gas system can be controlled automatically and the related important parameters such as furnace pressure are also controlled smoothly. In addition, it can improve the security level of the thermal power units and relieve the labor intensity of operators.

Study on Technical Measures for AGC Optimization in Fossil Fuel Power Plants

HOU Dianlai

2016, 49(6):  6-9.  DOI: 10.11930/j.issn.1004-9649.2016.06.006.04

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Aiming at the factors affecting the operation of AGC (Automatic Generation Control) system after the low NOx combustion retrofit implemented in the boiler, the reason analysis is conducted, and the specific measures are taken to improve the unit load control strategies. The measures include the boiler master control feedforward signal, the steam turbine load demand, the primary frequency control logic, the load adjustment by PAP (primary air pressure), and the control loops of the mill hot air and bypass air dampers. In addition, the combustion control model is improved based on the changes of the boiler’s features. The technical and economic analysis on these measures and the comparison between the control parameters have shown that the AGC indices are enhanced substantially.

Study on Technical Measures for AGC Optimization in Fossil Fuel Power Plants

HOU Dianlai

2016, 49(6):  10-14.  DOI: 10.11930/j.issn.1004-9649.2016.06.010.05

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Aiming at the factors affecting the operation of AGC (Automatic Generation Control) system after the low NOx combustion retrofit implemented in the boiler, the reason analysis is conducted, and the specific measures are taken to improve the unit load control strategies. The measures include the boiler master control feedforward signal, the steam turbine load demand, the primary frequency control logic, the load adjustment by PAP (primary air pressure), and the control loops of the mill hot air and bypass air dampers. In addition, the combustion control model is improved based on the changes of the boiler’s features. The technical and economic analysis on these measures and the comparison between the control parameters have shown that the AGC indices are enhanced substantially.

Application of Large Data Analysis on Characteristics Parameter Identification and Optimization of Steam Turbine Regulating Valves

WANG Gang, LIANG Zhengyu, LI Cunwen, YANG Tao

2016, 49(6):  15-19.  DOI: 10.11930/j.issn.1004-9649.2016.06.015.05

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As a major task in unit-grid coordination, accurate acquisition of the steam turbine regulating valve’s characteristics is the precondition for its precise control. Furthermore, it also affects the unit load stability, the qualities of primary frequency control and AGC performance. Presently, the turbine valve’s characteristics are obtained through field tests. Based on the large data analysis method, the turbine control valve’s characteristic parameters are accurately identified through historical data mining calculation. Therefore, towards the goal to linearize the flow characteristics of valve group, the optimized control valve’s flow management curve is acquired through computation.

Robustness Enhancement of Supercritical Unit Power Control with IMC-PID Controller

LI Xiaofeng, WANG Yagang

2016, 49(6):  20-24.  DOI: 10.11930/j.issn.1004-9649.2016.06.020.05

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This paper proposes a novel boiler-turbine coordinated control system in which the IMC-PID controller is adopted to tackle the power oscillation problem based on closed-loop identification in the turbine control loop. The set-point additive step disturbance is first imposed onto the closed loop to carry out frequency response characteristic identification using process inputs and outputs of the control loops. The process frequency-response matrix is then estimated, and a transform function matrix is obtained with the least square method. The robust PID controller of the turbine control loop is finally designed by using the internal model control(IMC) method based on the previously obtained model. The practical application shows that the IMC-PID controller maintains the robust performance and minimizes the effects of the external or the internal disturbances in the power plant, thus the occurrence of the power oscillation can be avoided.

Optimal Design of Drive Control Logics of Digital Control Systems in Nuclear Power Stations

LIU Yusui

2016, 49(6):  25-29.  DOI: 10.11930/j.issn.1004-9649.2016.06.025.05

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The traditional drive logic design methods, which are specifically for the relay based control systems, can no longer satisfy the new requirements of the digital control systems. This paper intends to solve this problem with a new optimal design technical route and an optimization procedure. A full open/close electric valve is taken as a case to illustrate the optimal design procedure of the drive logic in nuclear power stations. The optimal design methodology is further employed in the conventional island and BOP of Ling’ao second phase project to form the drive logic standard modularization, cancel some relevant relays, simplify the logic circuit, and reduce the error rate. With the methodology the accuracy of the parameters is guaranteed, and the reliability and safety of the units is improved, bringing high economic benefits to the enterprises.

Research on in-Depth Peak Load Regulation of Gas Turbine Generator Units at the UHV Receiving End

SU Ye, ZHANG Peng, ZHANG Yongjun, HE Yongjun, DAI Hangdan

2016, 49(6):  30-34.  DOI: 10.11930/j.issn.1004-9649.2016.06.030.05

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With more and more UHV devices connected to the power grid, it is of great importance to take advantage of the frequency control and peak regulation characteristics of generator units to ensure the security of power grid. Considering the peak regulation characteristics of gas turbine generation units, the factor analysis and test study are carried out on the impacts of fast start and in-depth peak load regulation during low load operation of the gas turbine generator units. The relevant data and experience are then obtained, which can provide references and thoughts to ensure the power system security by virtue of the peak regulation of gas turbine generator units under the circumstances of UHV grid connections.

Study on the Optimization of Air Supply Automatic Control for 650-MW Supercritical Units

SHEN Ming, SHEN Jian

2016, 49(6):  35-38.  DOI: 10.11930/j.issn.1004-9649.2016.06.035.04

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In view of the existing problems such as poor adjustment quality and incapability of auto switch-in in the air supply automatic control system of the 650-MW supercritical unit in a certain power plant, the optimizations on the air volume and the oxygen measurement instruments as well as the automatic control strategy are conducted. The practical operation shows that the optimized air automatic control system can meet the unit operation requirements under the 50%-100% static and variable loading conditions, which is helpful to improve the air automatic regulation quality and the commission rate.

Fault Analysis and Treatment of DLN 2.0+ Combustion System of GE 9FA Gas Turbine

SONG Shunli, ZHANG Ti

2016, 49(6):  39-42.  DOI: 10.11930/j.issn.1004-9649.2016.06.039.04

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Statistics show that the faults of the DLN 2.0+ combustion system happen most frequently in the operation of GE 9FA gas turbines. This paper introduces the structure of GE 9FA gas turbine DLN 2.0+ combustion system and the action sequence of each equipment in this system during the gas turbine startup, operation and shutdown process. The cause analysis on gas leak test failure, Gas Fuel Stop Valve (FSV) fault, Speed Ratio Valve (SRV) fault and gas purge fault is conducted, and the corresponding improvement measures are put forward. The application practice shows that the failure rate is significantly reduced after the improvement measures are taken.

The Present Status Analysis and Optimization Study of Shaft Seal Control of 1 000-MW Steam Turbines

LIU Lei, ZHANG Qiusheng, HE Zhiyong, LIANG Hua

2016, 49(6):  43-47.  DOI: 10.11930/j.issn.1004-9649.2016.06.043.05

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The shaft seal system of a 1 000-MW steam turbine of a power plant is introduced. Also the risks and potential dangers existing in the system are analyzed and summarized. Regarding the present status of the shaft seal system of steam turbines, specific rectification and optimization are conducted on the measurement and the control logics without touching the original design and the protection principles, which effectively improves the security of the unit operation and can provide reference for the steam turbines of the same type.

Research on Soft Measurement Technology of Typical Thermal Parameters of Utility Boilers

LUO Jia, CHEN Shihe, ZHANG Xi, WU Le

2016, 49(6):  48-52.  DOI: 10.11930/j.issn.1004-9649.2016.06.048.05

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In this paper, an algorithm for typical thermal parameters of utility boilers is proposed based on the least square support vector machine(LSSVM), in which the core issues, such as dynamic soft modeling and on-line updating of thermal parameters are intensively explored. Based on the boiler practical operation data, the proposed algorithm is verified with the carbon contents in the flying ash and the oxygen contents in the flue gas taken as cases. A software platform is designed and applied to the fly ash carbon and flue gas oxygen contents measurement for application verification. The software platform is tested in a 600-MW unit in Guangdong. The results prove the validity of the algorithm and the corresponding software platform.

Generation Technology

Analysis on Application of Active Power Transducer in Thermal Power Generating Units

YANG Tao, HUANG Xiaoming, XUAN Jiazhuo

2016, 49(6):  53-56.  DOI: 10.11930/j.issn.1004-9649.2016.06.053.04

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Through the analysis on the transient characteristics of analog power transducer commonly used in thermal power generating units, it is discovered that none of the analog power transducers of various types have exhibited satisfactory transient performance. In the event of faults or disturbances in the power grid, their output signal may be distorted, which will probably lead to valve misoperation. In addition, the analysis concludes that the long response time and small internal AT saturation are the root causes of the analog power transducer output waveform distortion. Therefore, a new type of power transmitting device is introduced. Based on the analysis on the existing problems in power transducer applications and alterations, it is recommended to replace the traditional power transducer with the new type of power transmitting device to prevent valve misoperation if the valve fast operation functionality is included in the unit DEH system.

Treatment of Troublesome Vibrations Caused by Steam Seal Modification in Steam Turbines

HE Guoan, MU Yuanjun, ZHAO Zhonghai, ZHANG Xueyan

2016, 49(6):  57-60.  DOI: 10.11930/j.issn.1004-9649.2016.06.057.04

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Steam seal modification can improve the thermal efficiency of steam turbines. Unfortunately it also may induce vibration problems in some units, among which some of them are quite stubborn and tough to be resolved. In this paper, the cause analysis is conducted on the vibrations observed after the honeycomb seal retrofit in the steam turbine shaft seal. The analysis concludes that the reason of the vibrations lies in the mismatch between the seal technical characteristics and the HIP shaft sealing process design, which causes the deformation of the steam seal and to some extents impedes the expansion of the HIP cylinder, thus consequentially gives rise to persistent frictional vibration at the steam seal. Based on the analysis, the paper also suggests that since significant temperature discrepancies exist between the seal steam and the casing temperatures in the HIP cylinder of many steam turbines under low load conditions, the honeycomb seal should be chosen with caution in order to avoid the frictional vibration problem.

Analysis on Torsional Vibration Caused by IDF Frequency Conversion in 1 000-MW Unit

CHEN Wei

2016, 49(6):  61-66.  DOI: 10.11930/j.issn.1004-9649.2016.06.061.06

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The measurement and spectrum analysis are taken on the process parameters of the fan, such as torsional vibration, torque and bearing vibration, under different conditions to find out the root causes of fan diaphragm coupling fracture and intermediate shaft crack. With the analysis, it is determined that the fan frequency conversion operation causes the torsional vibration and it is the root cause for the damage of the shafting system. Based on the fan shafting system modeling and simulation, the causes and solutions are figured out and suggestions for improvement are put forward.

Study on Energy Saving Technology of Electrostatic Precipitator Power Supply Device

YUE Jianhua

2016, 49(6):  67-71.  DOI: 10.11930/j.issn.1004-9649.2016.06.067.05

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Through studying the mechanism of power supply devices for electrostatic precipitators, a clear understanding of emission reduction and energy conservation characteristics is developed for different power supply devices, and an energy efficient power supply device is proposed with good performance in emission reduction and energy efficiency. Based on a research on applications of different power supply devices, the reason for poor performance of the pulse power source is identified. A combination scheme of different power supply devices is proposed according to the characteristics of dust and soot ratio.

Power System

A Study on the Emergency DC Power Support as the Third Defense of the Power System

LI Bijun, HUANG Zhilong, LIU Fusuo, ZHAI Haibao, LI Zhaowei, LI Jianhua

2016, 49(6):  72-77.  DOI: 10.11930/j.issn.1004-9649.2016.06.072.06

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The research and application of the DC system as part of the security and stability control of the power grid has been limited to the preventive control and emergency control, which are referred to as the first and the second defense line. Fully exploring the characteristics and control capability of the DC system is an important technical way to improve the safe and reliable operation of an AC/DC power grid. The concept of using the emergency DC power support capability as the third defense line of a power system is proposed. The coordination and cooperation of the emergency DC power support with the under-frequency-load-shedding and the over-frequency- generation-tripping can be applied to prevent system collapses. When abnormally low/high frequency is detected, the emergency DC power support can be activated to reduce the amount of load shedding or generation tripping. A preliminary design is presented on the control parameter setting calculation and the abnormal frequency control device. The beneficial results of the emergency DC power support as a control measure of the third defense line is validated by simulations based on actual grid operation data.. The issues concerning the use of the proposed concept as the third defense line are discussed in relation to the timing and control characteristics of the DC system. The findings have importance reference value for expanded technical options for the third defense line to support safe and reliable operation of the power grid.

The Online Isolation Test of Zhoushan Multi-terminal MMC-HVDC System

HUA Wen, LING Weijia, HUANG Xiaoming, QIU Peng, LU Yi, YU Miao, LU Cencen

2016, 49(6):  78-82.  DOI: 10.11930/j.issn.1004-9649.2016.06.078.05

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The theoretical and empirical analyses are carried out to verify whether or not the Zhoushan multi-terminal HVDC system has the capability of online isolating. The charging and discharging potential during isolating process is analyzed based on the topology of modular multilevel converter (MMC) and its sub-module, proofing theoretically the feasibility of online isolating. To ensure the safety of the field test, the isolating test was divided into two separate processes, an open line test with submarine cable and a terminal-to-terminal test. The field test at the Zhouding station verified the online isolating capability for the Zhoushan multi-terminal HVDC system and confirmed that the online isolating process neither impacts the field equipment nor results in dangerous overvoltage or sustained arc.

Study on Reactive Power Circulation Mechanism for High Voltage Common-Tower AC Transmission Lines

CHEN Jianhua, LI Yu, ZHANG Hao, LI Xuan, GUO Ziming

2016, 49(6):  83-89.  DOI: 10.11930/j.issn.1004-9649.2016.06.083.07

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In view of the typical problem of large reactive power flow difference and even reactive power circulation in some high voltage common-tower AC transmission lines, the mechanism of reactive power circulation is analyzed in this paper. An extended symmetrical component method and extended sequence impedance matrix are proposed based on the symmetrical component method. The analysis shows that the extended sequence impedance matrix is asymmetric, which implies that the mutual inductance will be not equal and even in the opposite direction for those phase un-conversed common-tower AC transmission lines. The result illustrates the causes for the reactive power circulation problem of the common-tower AC transmission lines. In order to solve the problem, a parameter decoupled equivalent method for the common-tower AC transmission lines is proposed, and the prerequisites for reactive power circulation phenomenon is derived, which explains the influencing factors and mechanism for the reactive power circulation problem of 220 kV Sanshao common-tower AC transmission lines. The validity of the proposed method has been proved by a case study of an actual power system.

Online Detection Device of Low or Zero Value Insulators in UHVDC Transmission Line

ZHANG Xian, LUO Richeng, ZOU Ming, PAN Junwen, TANG Xiangsheng, ZOU Dehua

2016, 49(6):  90-94.  DOI: 10.11930/j.issn.1004-9649.2016.06.090.05

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Due to time variation of leakage current, it is difficult to measure insulator resistance. The large amount of insulators also lead to heavy workload during online measuring. A ±800 kV UHVDC transmission line insulator insulation resistance testing device is designed to solve the problem. The device can climb on tension insulator strings and vertical insulator strings, measure insulation resistance without impact of leakage current under normal condition. Experimental data show that error margin of insulation resistance measurements is within 5% range. The device has ability to detect low or zero resistance value of line insulators under normal operation. The device is simple, flexible, reliable and has strong practical value.

A Review of Researches on the Influence of Insulator Configuration on Pollution Flashover Voltage of Polluted Insulator

ZHANG Liu，, CHAO Yafeng, HUANG Fuyong, WANG Cheng, WANG Feng

2016, 49(6):  95-100.  DOI: 10.11930/j.issn.1004-9649.2016.06.095.06

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The electric discharge mechanism and pollution flashover characteristics of stained insulators are the core elements of the research on technical measures preventing flashover caused by polluted insulators. To date, many experiments and theoretical investigations have been conducted worldwide, which generated many valuable results. This paper presents an overview of the researches over the last 30 years on pollution flashovers. It provides a systematic summary and analysis of various factors and mechanisms that influence pollution flashover voltage including factors such as physical characteristics of stained surface, flashing formation mechanisms, test methods, flashover characteristics and the mode of insulator configuration. It summarizes the relationships between the pollution flashover voltage and the mode of insulators configuration, and proposes appropriate insulator configurations under different environments.

Dynamic Differential Evolution Algorithm Based on Chaotic Sequences for Dynamic Economic Dispatch Problem of Power System

CHEN Guangyu, DING Xiaoqun, BIAN Erman

2016, 49(6):  101-106.  DOI: 10.11930/j.issn.1004-9649.2016.06.101.06

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Differential evolution (DE) algorithm is applied to solve dynamic economic dispatch (DED) problem and a dynamic differential evolution based on chaotic sequences (ADDECS) is proposed. Chaotic sequences is used in dynamic parameter settings adjustment in DE to keep population diversity. Dynamic search strategies including both global and local search strategy are used to improve algorithm efficiency. To accelerate convergence and deal with complicated constraints of DED problem, constrained process mechanism based on multi-objective concepts is adopted. A new constraint process approach is proposed to allocate infeasible constraint violation proportionally among units according to their regulatory abilities. At the same time, different mutation strategies and improved random search are used to guide population evolution and to enhance global search ability. The feasibility and effectiveness of proposed method is verified on a 10-unit test system. Compared with other methods, ADDECS can obtain better solutions in shorter computational time along with higher robustness.

Research on Influence of Air Gap Discharge on HVDC Line’s Lightning Performance

ZHANG Ting, HONG Xin, RAN Hongwei, ZHANG Xiaoliang

2016, 49(6):  107-111.  DOI: 10.11930/j.issn.1004-9649.2016.06.107.05

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HVDC double circuit transmission line can save transmission line corridor resource. However, the small air gap between transmission line and tower leads to easy flashover instead of insulator which affects lightning performance. After simulation, lightning withstand levels in different transmission line forms with or without air gap-flashover are compared. The results show that back stroke lightning withstand level and shielding performance level are both reduced with consideration of air gap discharge, while lightning flashover rate is raised．Air gap has to be taken into consideration in evaluating HVDC lightning performance.

Analysis and Optimization of High Voltage Electric Field Shielding Scheme of Transmission Corridor in Residential area

PENG Chunhua, JIANG Lei, CAI Zhongqi, SUN Huijuan

2016, 49(6):  112-119.  DOI: 10.11930/j.issn.1004-9649.2016.06.112.08

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In order to solve problem of high power frequency electric field in residential buildings caused by nearby high voltage transmission corridor, shielding effectiveness of different shielding methods and their space construction are studied based on finite element calculation. Through simulation calculation of distorted electric field, the relationship between shielding method and effectiveness is analyzed. A new method to improve shielding effect is proposed by optimizing space construction model. The power frequency electric field shielding schemes for four voltage level high voltage transmission line, ranging from 110 kV to 1 000 kV, are designed with consideration of shielding effect and construction cost. The research shows that shielding effectiveness could be improved greatly by reasonable selection of shielding method and optimized mounting position. This is very important for reducing environmental cost of transmission project.

Test Study on Key Tubes and Connections of the Steel and Concrete Composite Structures for Long-Span Power Transmission Tower

XIE Fang, CHEN Ju, JIN Weiliang, FENG Bing

2016, 49(6):  120-125.  DOI: 10.11930/j.issn.1004-9649.2016.06.120.06

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In order to provide reference for the design of composite structure power transmission tower, the test study is carried out to investigate key technologies such as the concrete-filled steel tubes with lattice angle, and the concrete-filled steel tubular connection. These investigations produce results on stability, failure mode, and bearing capacity of the concrete-filled steel tube with reinforced lattice angle, as well as the chord-wall deformation, stress concentration factor, and bearing capacity of the concrete-filled steel tubular connection. Finally, a bearing capacity calculation methodology is proposed, which could be used for the design of similar structures.

Key Technologies of Large-Scale Automatic Test of Smart Meters

SU Huiling, , WANG Zhongdong, , CAI Qixin, , SONG Ruipeng, , LI Wei,

2016, 49(6):  126-131.  DOI: 10.11930/j.issn.1004-9649.2016.06.126.06

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Key technologies of large-scale automated verification of smart meters are dicussed from data interaction, dispatching control and intelligent diagnosis. First, an application architecture of discrete automatic test is built from multi-dimensional sense using WCF(Windows Communication Foundation) and MQ(Active Message Queue) communication mode. A method combined with feedforward and feedback control is proposed to ensure accuracy and reliability of interactive data. Second, time-space dispatching control strategy is constructed based on the automation verification control framework. Third, combined with fault-knowledge library,“Alarm- Discovery-Diagnosis-Resolution-Study” method is used to construct intelligent diagnosis. The proposed methods are effective for accurate and reliabile data interaction, cooperation of automatic test and operational efficiency.

Investigation on Loss and Heat Dissipation Characteristics for Power Transformer Systems

SHAO Zhiwei

2016, 49(6):  132-136.  DOI: 10.11930/j.issn.1004-9649.2016.06.132.05

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Losses and heat dissipation of oil-filled transformer are key operation factors. To gain accurate value of heat dissipation of typical transformer system, the heat dissipation is calculated by using flow convection along a flat plate, natural convection in infinite space and diffuse gray surface radiation model. Heat dissipation characteristics are obtained through calculated results. The results show that heat dissipation is achieved mainly through radiator, accounting for 77.66 %~85.31% of total amount of the transformer system. The transformer heat is primarily dissipated by radiation, accounting for 55.15%~70.25%. However, the heat dissipated for radiator is mainly through convective and only accounts for 2.18%~11.34%. Compared with the transformer system losses, loss empirical formula is suitable for the transformer system because the error margin is less than 10%. Transformer loss is closely related to type and load factor. Different types of transformer have different losses. Under same load factor, the loss increases with the transformer capacity. The loss also increases with the load factor for the same transformer type.

An Online Power System Smart Restoration System Integrated with D5000 Dispatch Platform

LIU Xinyu, WU Yingxia, FENG Li, SHI Chenggang, LI Changcheng, ZHANG Pei, LIU Cong,WANG Xiaojun, LIU Hai, WANG Shu

2016, 49(6):  137-140.  DOI: 10.11930/j.issn.1004-9649.2016.06.137.04

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Power system restoration is a highly complex decision and control problem. An online power system smart restoration (PSSR) tool is developed based on decoupling complex problem into multiple stages associated with different objectives and constraints. The software is able to obtain real-time data from D5000 dispatching platform. Based on actual system conditions, PSSR can assist operators in developing detailed restoration strategies without violating operational constraints. The developed system has been deployed in Chongqing Electric Power Company and generated effective system restoration strategies. Implementation of PSSR can increase system operators’ capabilities of restoring system, reduce outage time and improve system reliability.

Research on the Connectivity of Distribution Network Island Based on Graph Theory

SHI Quansheng, LU Yanan

2016, 49(6):  141-145.  DOI: 10.11930/j.issn.1004-9649.2016.06.141.05

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A large number of distributed generation(DG) has accessed to the distribution network which makes the structure of the distribution network complicated. When a fault occurs on a trunk line in distribution network, it is needed to disconnect the faulty part of distribution networks from the grid, and reconfigure the distribution networks. The utilization of DG to recover the part load supply can improve both the reliability of distribution network and the utilization rate of the distributed power supply. In order to maintenance the stable operation of the reconfigured network, it is needed to distinguish the connectivity of islanding system after the reconfiguration. The conventional discriminant method only considers the traditional standby power but ignore the large number of distributed generators. In this paper, the improved breadth-first search algorithm is used to distinguish the connectivity blocks of the distribution network, and a 19-node system with distributed generation is adopted in the case study. The results show that the proposed algorithm can not only search the multiple connected blocks of the distribution network containing DG, but also can accurately distinguish the electrical connectivity of each connected block.

Study on Prediction Model for Shanghai Monthly Power Consumption

MU Haizhen, SUN Landong, HOU Yiling

2016, 49(6):  146-150.  DOI: 10.11930/j.issn.1004-9649.2016.06.146.05

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Accurate mid- to short-term prediction of power consumption is the precondition for formulating a scientific power grid operation program. By investigating the series data of Shanghai City, including monthly power consumption(MPC), air temperature(AT), gross domestic product(GDP), population and energy consumption per unit of GDP (ECUG), the main influencing factors of MPC are obtained in this paper, and a MPC prediction model is developed through the Yearly Change Rate(YCR) method. The forecast results show that the YCR method can effectively eliminate the impact of background trend on correlation analysis results and helps to improve understanding the relationship between AT and MPC; the MPC of Shanghai has two summits of winter and summer and shows a tendency of increase as influenced by the increase of economic scale; The YCR of MPC in winter and summer is closely related to temperature variations, while the YCR of MPC in spring and autumn is mainly related to the economic growth and industrial structure adjustment; Taking into account of various influence factors, the MPC prediction model is suitable for power consumption forecast as well as economic situation analysis.

Energy Conservation and Environmental Protection

Study on the TiO₂ Recovery from SCR Catalyst Waste in Coal-Fired Power Plants

CHEN Yingmin, XIE Zong, WANG Chaofan

2016, 49(6):  151-156.  DOI: 10.11930/j.issn.1004-9649.2016.06.151.06

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It is of great significance to recover the valuable metals from the inactive SCR denitration catalyst waste and make them recycled. Taking the waste SCR catalyst from a thermal power plant as the study object, the titanium dioxides are recovered with sodiumzation-calcinating technology from the abandoned SCR catalysts. In addition, the effects of sodium carbonate and dilute sulphuric acid dosages, the leaching water volume, time and temperature, and the calcinating time and temperature on the recovery rate are studied. The results indicate that the processes of sodiumzation-calcinating, raw material extraction and sulphuric acid washing have great impacts on the titanium dioxide extraction. Under the optimal condition, the recovery rate reaches as much as 92.15% with the product purity of 96.28%. The feasibility analysis shows that the developed SCR catalyst recovery program has good economic returns.

Application of Wet Electrostatic Precipitator in Coal-Fired Power Plants

WANG Xianna， ZHU Lin, WANG Dongge, WANG Kang

2016, 49(6):  157-160.  DOI: 10.11930/j.issn.1004-9649.2016.06.157.04

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Taken the practical projects as examples, the particulate matter removal effects of wet electrostatic precipitators(WESP) are explored. The results indicate that WESP can effectively decrease the emissions of particulate matters(e.g. PM2.5, PM10), but at the WESP outlet, some particles still have small peak values. In order to improve the collection efficacy of the particulate matters, the WESP combined with coalescence method is adopted. The results indicate that the WESP combined with coalescence method can greatly enhance the removal; the efficiency in both PM1 and PM2.5 removal reaches more than 80% and the general efficiency of the dust removal system reaches more than 90%, which enables the generation units to meet the requirements of ultra-low dust emission.

Treatment and Control on Pipeline Blockage in SCR Denitrification System

HE Donghong

2016, 49(6):  161-165.  DOI: 10.11930/j.issn.1004-9649.2016.06.161.05

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The malfunction occurrences in ammonia systemendangers the safe operation of the whole SCR denitrification system in thermal power plants. Based on the theoretical analysis and the denitrification equipment maintenance practice, a few approaches and controlling tactics are proposed, including controlling the ammonia quality fundamentally, setting filters on correct places, preventing metals from corrosion, clearing the steam-heater momentarily, setting by-pass at the flow meter, covering and equipping the feed pipes and the valves with thermal insulation and ammonia heater, enhancing timely repairment and maintenance, and improving the control valve logics. The practical operations show that the proposed measures are effective in avoiding the problems to happen.

Study on Carbide Slag-Gypsum Wet Flue Gas Desulfurization Process Technology

LANG Lei

2016, 49(6):  166-169.  DOI: 10.11930/j.issn.1004-9649.2016.06.166.04

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In the operation process of carbide slag-gypsum wet flue gas desulphurization, problems, such as severe abrasion, high slurry pH value in the tower, hard oxidation of calcium sulfite and difficult dewatering of the vacuum belt dewatering machine, are common in the equipments and the pipelines. In this paper, the carbide slag particle size and chemical composition are analyzed through sampling, and the oxidation of calcium sulfite formed in the carbide slag desulfurization process is studied through tests. The study results show that the physical and chemical properties of carbide slag differ substantially from those of limestone, therefore, the carbide slag-gypsum wet flue gas desulfurization process design and equipment and material selection should not follow blindly the limestone-gypsum wet flue gas desulfurization process. Solutions to these problems are put forward, such as carbide slag pretreatment, reasonable material selection, and separation of SO2 absorption from calcium sulfite oxidation.

New Energy

Study on Aggregate Electric Vehicle Charging Load Model and Simulation for Clean Energy Accommodation in Distribution Network

AI Xin, ZHAO Yuequn, ZHOU Shupeng

2016, 49(6):  170-175.  DOI: 10.11930/j.issn.1004-9649.2016.06.170.06

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The model and control method of aggregate electric vehicle(EV) charging loads are studied in the paper, including the direct load control method for accommodation of the uncertain clean energy. It is assumed that the dispatch department can direct control the charging power by broadcasting a universal control signal in real time to complete the wind power accommodation. First, the aggregate electric vehicle charging load model based on a partial differential equation is established by using the transport-based load method. Then, model simulation is conducted based on the real resident travel data, and the model’s effectiveness is verified by Monte Carlo simulation. A SMVSC-based novel control strategy is proposed, which can track the wind power output by using the difference between supply and demand in real time. Finally, the control strategy is verified through the real wind power output curve, which can provide a new method for clean energy accommodation.

ARIMA Model Forecast for Wind Power Time Series with Different Temporal Resolutions

ZHANG Lidong, LI Jiying, WU Ying, YU Kansheng, ZHU Mingliang, CHI Junyu6

2016, 49(6):  176-180.  DOI: 10.11930/j.issn.1004-9649.2016.06.176.05

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By taking a wind turbine of a farm as a case, the ARIMA model is used to predict the wind power time series according to five time resolutions. The results show that the number of characteristic points of power time series decreases with the reduction of time resolution until the characteristic point disappears completely. The mean absolute error (MAE) is used to analyze the prediction results, and it is concluded that the absolute error of the ARIMA-predicted results decreases gradually with the increase of time resolution with the MAE of 1min resolution being the minimum.

Economic Analysis on High PV Modules Capacity Ratios

WANG Shujuan, XUE Manyu, LIU Songmin

2016, 49(6):  181-184.  DOI: 10.11930/j.issn.1004-9649.2016.06.181.04

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The output of photovoltaic modules can hardly reach the nominal power due to the characteristics of solar resources. Therefore, the utilization rate of electrical equipment is low. The cost of per kWh PV generation can be reduced through improving the utilization rate of electric equipments by changing the capacity ratio of PV modules and electrical equipment. Based on an analysis of the solar energy resources of two cities, the Golmud City with abundant solar resources and the Nanjing City with relatively poor solar resources, the output power of PV modules with different capacity ratios and the power reaching inverter after output power reduction is calculated in this paper. Then the power limit ratios of PV projects with different capacity ratios are analyzed and the PV generation increment with different capacity ratios is accordingly calculated. The increments of initial investment and annual operating costs under different capacity ratios are determined. Finally, based on the calculated increments mentioned above, the internal rate of return(IRR) of the investment increment is analyzed.