Table of Content

25 September 2017, Volume 50 Issue 9

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Special Contribution

The Economic Principles of Electricity Wholesale Market Design

LIU Shujie, YANG Juan

2017, 50(9):  1-10.  DOI: 10.11930/j.issn.1004-9649.201707123

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This paper discusses the design principle of electricity wholesale market from the perspective of economics. Electricity is a system integrated real-time product. The security and reliability of power system is the material premise of electricity competition. However, the reconstruction of electricity transaction relationship and the institutional arrangement of competitive electricity transaction are essence of electricity market. The differences of transaction relationship and “right and responsibility equality” between unilateral and bilateral competitive electricity markets lead to significantly different structure of energy market and clearing mechanism of energy spot market. Thus, there are two different modes of electricity transaction: “unilateral transaction”, known as “mandatory electricity pool” and “bilateral transaction”, named as “bilateral transaction + balancing mechanism”. The scientific design of the electricity market should be based on the qualitative identification of transaction relationship and take the “right and responsibility equality” as the main line, and then choose a cost effective mode of electricity transaction according to cost-benefit analysis.

Power Planning

Electricity Consumption Forecasting of China During the Period of the 13th Five-Year

DU Zhongming, WANG Xuesong

2017, 50(9):  11-17.  DOI: 10.11930/j.issn.1004-9649.201706123

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Electricity consumption forecasting is an important basis for the power industry development planning during the period of the 13th Five-Year. The new momentums drive the development of the electricity consumption of China under the new economic normal, which include power demand of the second industry represented by the high-end manufacturing industry, power demand of the third industry represented by the modern service industry and power demand of residents living driven by the new urbanization. China is in the stage of transition from the middle of industrialization to the later stage. Under the situation of economic structure adjustment, transformation and upgrading, it is difficult for the two-digit high speed growth to appear again similar to the period of the 10th Five-Year and the 11th Five-Year. At present, there is still a big gap between China and the developed countries in the level of per capita electricity consumption. Therefore, the future electricity demand of China still has great potential for development. The low electricity consumption growth rate is not consistent with the electricity consumption development experience of relevant nations and regions. Methods such as per capita electricity consumption, electricity elasticity coefficient, various sub sectors and quantitative economic model are used for forecasting the electricity consumption of China in this paper. It is predicted that the electricity consumption of China during the period of the 13th Five-Year will keep a rigid growth.

Study on Power System Planning Method Adapting to New Energy Development

XU Lin, HUANG Xiaoli, DU Zhongming, ZHANG Tao, LI Zhenjie, CHENG Linyan

2017, 50(9):  18-24.  DOI: 10.11930/j.issn.1004-9649.201706124

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Power-energy balance and peak regulation method is presented to adapt to the new energy development in power system planning. Firstly, with the convergence condition of given LOLE value, the power-energy balance is obtained by the convolutional integration of probability-distribution functions of the output of thermal and new-energy plants. Secondly,the over-supplied indices is also presented and used to evaluate the peak regulation capability of power system and the abandoned new energy in the case that all thermal plants are in their minimum technical capacity. Case studies show that the presented method is suitable for the variable-output of new-energy generators, which can evaluate their capability-effects correctly. The presented peak regulation method is more necessary in power system with rich new-energy, because the energy is abandoned so frequently for variable-generations.

Study on the Energy Development Demand and Smart Grid Construction Under New Situation

HUANG Xiaoli, LI Zhenjie, ZHANG Tao, GU Han, CHEN Guodong, ZONG Zhigang, DUAN Wei

2017, 50(9):  25-30.  DOI: 10.11930/j.issn.1004-9649.201707113

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The problems of resources and environment bring an urgent necessary for the transformation and upgrading of energy production, transmission and utilization, which can be effectively solved through development of the smart grid. In this paper, the relationship among the smart grid, smart energy and energy internet is discussed firstly. The new situation under the development of the energy and electric power industry is analyzed in depth. It is concluded that the smart grid is the essential path for the development of energy and electric power industry. Then, the general architecture of the smart grid development is proposed from 9 aspects in terms of production, transmission, distribution, utilization, etc. The importance and significance of the smart grid are expounded in promoting energy transformation, constructing smart city, industrial upgrading and other aspects. In summary, it is helpful for the sustainable development of energy, and the healthy and rapid development of social economy to keep development of smart grid as core task and fully play its fundamental role in construction of smart energy and smart city construction.

Analysis on Influencing Factors of Energy Demand Based on Interpretative Structural Modeling

WANG Jingmin, KANG Junjie

2017, 50(9):  31-36.  DOI: 10.11930/j.issn.1004-9649.201607096

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The energy demand system is not only affected by various factors inside energy system, but also influenced by various other factors including economic development, social natural environment, population factor, technological progress. It is a typical nonlinear system with very complex relationship among various factors. System engineering methods are used to analyze influencing factors of energy demand and relationship amongthem. The interpretative structural model is used to analyze hierarchical relationshipamong influencing factors of energy demand. Surface factors, intermediate factors, core factors and source factors that affect energy demand are summarized. The analysis shows that population, urbanization level, living standard, energy consumption structure and energy use efficiency are direct influencing factors of energy demand change. The economic development level is the core factor, and the source factors can be divided into three categories: international economic situation, various related policies and major activities.

Optimizing Sichuan Clean Energy Delivery by Hydro/Wind Power Complementation

CHEN Hanxiong

2017, 50(9):  37-43.  DOI: 10.11930/j.issn.1004-9649.201605102

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Hydropower and wind power of Sichuan Provincial have substantial surplus of electricity quantity and seasonal complementary character. In order to take advantage of clean energy of Sichuan grid and power transmission capability of 4 UHVDC transmission lines in Sichuan system, study of optimizing annual delivery quantity of Sichuan electricity with consideration of hydropower/wind power complementation character is performed. By achieving optimal allocation of Sichuan green clean energy in greater range, economic efficiency of 4 UHVDC transmission lines in Sichuan system can be improved. The result shows that annual utilization hours of 4 UHVDC transmission lines can be increased by 75~280 hours after optimization.

Planning and Typical Engineering Application of Distribution Automation

ZHANG Tao, TIAN Bin, ZONG Zhigang, YU Yuan, YANG Gang, MIAO Zhu, A Sileng

2017, 50(9):  44-51.  DOI: 10.11930/j.issn.1004-9649.201706140

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Distribution automation, as one of the important development direction of distribution network, is the key method to promote distribution automation level, shorten blackout time, enhance power supply reliability, and guarantee the power supply reliability. Based on summary of existing problems and development tendency of distribution automation, function and orientation of distribution automation are clarified, and a comprehensive distribution network planning and constructing scheme is proposed. Also, typical application scenarios are analyzed. During planning and constructing of distribution automation, features and key problems should be determined on comprehensive analysis of current situation. Meanwhile, grid structure optimization, pattern selection, master station construction, terminal configuration, device transformation and coordinated management should be fully considered during distribution automation system construction. The programming scheme and idea have been applied in eight leagues in the Inner Mongolia region, which significantly improve operation and management level.

Overview of the Hybrid Solar Coal Power System

PENG Shuo, ZHOU Xian, WANG Baomin

2017, 50(9):  52-58.  DOI: 10.11930/j.issn.1004-9649.201608026

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This paper reviews the current development of the hybrid solar coal power system, summarizes the progress of the researches on the thermodynamic performance of the system and presents the evaluation criterion of the system. Then, the paper conducts the analysis on the economic performance of the system. At last, the demonstration power plants both in China and abroad are introduced.

Power System

Analysis on V-String Offset and Unbalanced Tension Forces Under Broken Iced Conductor of ±1 100 kV Transmission Lines

YANG Fengli, LI Zheng

2017, 50(9):  59-65.  DOI: 10.11930/j.issn.1004-9649.201611114

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By applying the scheme of stretching the V-string into the tower body, the length of the cross arm of ±1 100 kV transmission tower can be shorten. As a result, the tower weight and the corridor width can be reduced. The V-string offset with broken iced conductors is an important controlling parameter for determining the layout scheme of V-string stretching into the tower body. Accurate calculation of the dynamic unbalanced tension forces of the broken iced conductor can provide the basis for checking the structural strength of the lighting protectors of transmission lines. A seven-span conductor-V-string finite element analysis(FEA) model of ±1 100 kV line section is established with general software ANSYS. The initial tension force of conductors can be applied by lowing temperature method. The damping of the conductor-V-string system is realized by Rayleigh damping form. Four sub-conductors are assumed to be broken simultaneously. The conductor elements at the broken point are killed for realizing the broken conductor simulation. By using nonlinear transient analysing method, the time histories of the V-string offset and the unbalanced tension forces at the suspension point with and without sub-spacers are calculated. When considering the effect of the sub-spacers, the peak values of the V-string offset and the unbalanced tension forces are lower than the design values calculated by static model without sub-spacers. It is safe to determine the scheme of V-string stretching into the tower body and the unbalanced tension forces according to design values.

Rapid Search of Cascading Failure Serious Paths in Power Systems Based on Vulnerable Line Identification Results

YANG Chaoping, MA Zhiyuan, SHEN Chen, ZHANG Shuang, GU Yujia

2017, 50(9):  66-71.  DOI: 10.11930/j.issn.1004-9649.201612112

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In order to balance the search accuracy and efficiency, this paper proposed a new algorithm, which is based on vulnerable line identification results and operation status of power systems and is suitable for the rapid identification of serious fault paths. Firstly, the modified k-core method was introduced to rapidly recognize the vulnerable lines in power grid. Secondly, the cascading failure development in the direction that may lead to serious power losses was identified by specifying the first two cascading failure components as the vulnerable lines, so as to improve the efficiency of prediction. The case studies are carried out on the IEEE 39-bus test system to demonstrate the validity and effectiveness of the proposed method.

Configuration of Last Breaker Trip Function for Chongqing-Hubei Back-to-Back HVDC Project

ZHANG Qun, ZHAO Qian, HAO Junfang, YAN Bing, CHEN Peng, KONG Lingkai

2017, 50(9):  72-76.  DOI: 10.11930/j.issn.1004-9649.201607042

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The removal of all AC lines and load shedding of inverter station in flexible HVDC system will cause overvoltage at the DC side and other parts in inverter station, which may endanger the safety of primary equipment. Therefore, the configuration of last breaker trip function in inverter station is very necessary. In this paper, based on the Chongqing-Hubei back-to-back HVDC project, a configuration scheme of last breaker trip function for flexible HVDC system is proposed, and is verified by RT-LAB real-time simulation platform which is integrated to the control and protection system and operators monitoring system. The results show that the configuration of last breaker trip function can ensure the locking of converter valves before tripping of the AC circuit breaker or before the DC voltage increasing to the protective setting value so as to avoid serious overvoltage at both AC and DC sides.

Study on a New-Type Phase Adaptive Power System Stabilizer and Its Simulation

LU Cencen, WU Kuayu, WU Long, HAN Bing, SHEN Yijun, LU Haiqing

2017, 50(9):  77-83.  DOI: 10.11930/j.issn.1004-9649.201610053

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The hysteretic characteristic of generator excitation system weakens generator damping, thereby increasing the risk of low frequency oscillation. Most typical power system stabilizer(PSS) models use multistage advance steps to compensate the hysteretic characteristics, which results in limited gains and insufficient damping of middle-low frequencies. A new PSS design idea is proposed in this paper, in which the input is a synthetic phasor of active power negative variation and rotating speed variation, and the phase advances automatically. It can solve the problem of multistage advance compensations. Theoretical analysis and simulation calculation have verified the adaptive phase ability of the new PSS and its ability for suppressing the low frequency oscillation, recovering from large-disturbance faults and the reverse regulating effects.

Information and Communication

Design and Implementation of the Hand Held Power Substation Inspection System

TAO Li, ZHU Xiaoguang, WANG Shanhong

2017, 50(9):  84-88.  DOI: 10.11930/j.issn.1004-9649.201604019

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Substation inspection is critical for power system secure operation management. With the rapid development of smart grid, it is urgently needed to develop a set of convenient and practical power substation inspection system, to make the inspection more accurate, the data more complete, and the operation procedures more clear. In this paper, the design and implementation of the handheld power substation inspection system is introduced. It combines the intelligent identification and mobile data transmission technology of IOT. Using a portable mobile terminal,it can identify the equipment and accomplish the inspection management through two dimensional code scanning. Inspection results are also automatically summarized and reported electronically. Furthermore, with paperless account management, it can provide end-to-end inspection solutions. This system can be operated independently. It can also provide data services for other systems and is helpful for management standardization. The system has been applied to the 110 kV Long Gang substation, and its easy and straightforward operation has been unanimously recognized on field. There is no doubt that it can be further extended to other application areas.

Research on Modeling of Low-Voltage Power Line Background Noise by Wavelet Neural Networks

SUO Chaonan, ZHAO Xiongwen, ZHANG Hui, LU Wenbing

2017, 50(9):  89-94.  DOI: 10.11930/j.issn.1004-9649.201606111

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In order to improve anti-interference ability of power line communications, a new modeling method for colored background noise and narrowband noise based on wavelet neural network is proposed. Firstly, the background noise is modeled by wavelet neural network. The output noise waveforms and power spectrum densities (PSD) obtained from model are compared with test noise by calculating root mean square error(RMSE). Moreover, the background noise is also modeled by traditional wavelet packet transform and peak typed Markov chain. RMSEs of PSDs before and after modeling are also calculated. Simulation results show that both output noise waveforms and PSD obtained by proposed model have good agreements with test noise. The RMSE is smaller than the value generated using wavelet packet transform and peak typed Markov chain. Therefore, the proposed wavelet neural network model is effective in modeling background noise, especially for the wideband colored background noise.

Research on Innovative System of Intelligent Power Utilization and Interactive Service for the Internet+Power Marketing

TU Ying, ZHU Jiong, QIU Huadong, WANG Xiaowen, JIANG Lei

2017, 50(9):  95-99.  DOI: 10.11930/j.issn.1004-9649.20160041

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Based on new era of deep integration between “Internet +” and traditional industry, an “internet + power marketing” innovative system of intelligent and interactive service is presented. The architecture of intelligent and interactive service is described, which consist of resources support, data support, business management and operations management. The proposed system has been applied in practice partially which shows its advantage and effectiveness.

Application and Process Design of Statistical Analysis and Evaluation in Power Communication System

YU Liangliang, ZHAO Yongbin, ZHAO Jinghong

2017, 50(9):  100-104.  DOI: 10.11930/j.issn.1004-9649.201606043

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Statistical analysis and benchmarking evaluation are important work contents in power communication system, but they have not been effectively applied and managed. The statistical analysis and benchmarking evaluation carried out by manual calculation is overloaded and inefficient. Based on the application status quo of statistical analysis and benchmarking evaluation in power communication system, an application platform concept is proposed, in which the management processes of statistical analysis are designed respectively for two different data collection strategies, and their advantages and disadvantages are also analyzed. In addition, the management process of benchmarking evaluation is also designed, which will play a positive role in promoting safe production and management.

Energy Conservation and Environmental Protection

Analysis on Design and Procurement of the Catalyst for Ultra Low Emission Reconstruction Project

YAN Min, LI Chao, ZHU Yue

2017, 50(9):  111-115.  DOI: 10.11930/j.issn.1004-9649.201609052

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Along with the nitrogen oxide emission restrictions getting more stringent, ultra low emission retrofit will be carried out throughout all domestic coal-fired power plants. Based on the analysis and summary of the quality and operation characteristics of the in-service denitrification catalyst, in order to standardize and enforce the procedures in the catalyst design and procurement, by taking account of the current production status of denitration catalyst, the operation of denitration equipments as well as the test results of denitration catalyst in the recent 3 years, this article presents detailed issues for specific attentions in the design and procurement of the catalyst for the ultra low emission reconstruction in the SCR denitration device of current domestic coal-fired power plants. Especially, the possible problems are analyzed in the design and purchasing technical agreement for extra layer catalyst.

Study on Application of Economizer Feedwater Bypass to Increase the Flue Gas Temperature

GUAN Jian, XIANG Qunyang, SHEN Li, SHEN Weijun, QIU Lichun

2017, 50(9):  116-120.  DOI: 10.11930/j.issn.1004-9649.201605070

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Aiming at the problem of unusable SCR denitrification system due to the low inlet flue gas temperature during the medium and low load operations of a 300 MW coal-fired boiler, an economizer feedwater bypass technology is applied to raise the SCR inlet flue gas temperature. Based on the bypass tests at typical loadings, the effect of the economizer feedwater bypass on the enhancement of the flue gas temperature is validated and the influence on the boiler operation is studied. Besides, considering the potential risks of the evaporation of the saturated feedwater on boiler safety, a real-time bypass safety flow-rate computing model is established. Therefore, the real-time safety flow-rate is obtained, which can guide the application of the bypass technology. The study results can provide valuable reference for the wide-load denitrification of power plants.

The In-Depth Research on PM and SO₃ Simultaneous Removal by Low-Low Temperature ESP Technique

CAO Yufeng, YAO Yuping, LIU Hanxiao, LI Wenhua, LI Jianguo

2017, 50(9):  121-124.  DOI: 10.11930/j.issn.1004-9649.201609019

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In recent years, to realize ultra-low emission of air pollutants from coal-fired power plants, the application of low-low temperature ESP technique has just stepped onto the stage. Taking the low-low temperature ESP of 660 MW unit in Zhejiang Wenzhou Power Plant as the research object, the PM and SO₃ simultaneous removal effects of low-low temperature ESP are tested, and the resistivity of fly ash and its impact on dust removal efficiency at low-low and regular temperatures are studied. The results show that since the flue gas cooler is put into operation, the working condition resistivity of fly ash under low-low temperature has been lowered by ten times compared with the regular working conditions. The emission mass concentration of dust has been decreased from 6.94 mg/m³ to 3.25 mg/m³, which meets the ultra-low emissions requirements, and the SO₃ removal rate reaches 96.6%.

Analysis on the Impacts of Low-Low Temperature Eletrostatic Precipitator on Dust Characteristics and SO₃ Removal Effect

DU Zhen, YANG Liqiang, WEI Hongge, YE Weiping, ZHU Yue

2017, 50(9):  125-128.  DOI: 10.11930/j.issn.1004-9649.201607139

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This paper analyzes the impacts of low-low temperature electrostatic precipitator(ESP) on dust characteristics and SO₃ removal efficiency, and concludes that the low-low temperature ESP can improve the dust chargeability by reducing the dust resistivity, thus effectively improves the dust removal effect. Moreover, increasing the average diameter of the dust is good for improving the collaborative dust removal effect of the desulfurization system. The wet desulphurization system does not have high SO₃ removal efficiency, while the low-low temperature ESP and the wet ESP can remove about 80% of SO₃. Therefore, the low-low temperature ESP and the wet ESP are more effective to control SO₃.

The Integrated Design Technology for Simultaneous Dust Control and Desulfurization System Based on Bayes Network Model

WANG Yifei

2017, 50(9):  129-134.  DOI: 10.11930/j.issn.1004-9649.201606172

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Based on the theoretical and data analysis, this paper finds out the design and operation parameters of the desulfurization system capable of removing the dust simultaneously, then builds up the Bayes Network Model and trains the model with a large number of the design and operation data collected from the units adopting simultaneous dust removal and desulfurization technology. The model quantifies the impacts of desulfurization parameters on dust removal efficiency and is integrated into the design system to conduct future reconstruction for dust simultaneous control, and solve the problem of excessive dust emission in the applications of the desulfurization system with simultaneous dust removal technology in coal fired power plants. The integrated design system has been successfully used in several coal fired power plant of China Datang Corporation. After reconstruction, the dust emissions at the inlet of the chimney have met the designed target and been stabilized for long term.

Feasibility Analysis on Reusing Treated Industrial Wastewater for Desulfurization Process Water in Power Plants

SUN Lijiao, YE Zhian, HU Teli, LI Rongxuan, CAO Ruixue, WANG Hongbin

2017, 50(9):  135-137.  DOI: 10.11930/j.issn.1004-9649.201610016

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In order to improve the utilization rate of the entire plant water resources, the quality of treated industrial wastewater in one thermal power plant of Hebei Province is compared with the quality requirements of desulfurization process water, which concludes that they are quite close to each other. Since the amount of the treated industrial wastewater accounts for only 7% of the total desulfurization process water, it is decided to use it as desulfurization process water. To further eliminate the risks and make the utilization plan properly, the on-site testing study is carried out. The results show that the desulfurization system runs normally after the treated industrial wastewater is served as the influent water for desulfurization. Meanwhile, this system has a desulfurization efficiency of no less than 95%. The slurry density maintains at 1 130 kg/m³ during the operation process. The water ratio of the gypsum as the desulfurization byproduct is about 10%, and the weight percentage of CaCO₃ is less than 3%. The purity of CaSO₄·2H₂O is above 90%, which satisfies the market requirements for the quality of gypsum. Therefore, the treated industrial wastewater is eligible to be reused in desulfurization process.

Generation Technology

The Reheat Steam Temperature Control Strategy for the 1 000 MW Ultra-Supercritical Double-Reheat Unit and Its Application

NIU Haiming, QIU Zhongchang, HUANG Huanpao

2017, 50(9):  138-142.  DOI: 10.11930/j.issn.1004-9649.201703066

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Through the analysis on the effects of the temperature control methods on the reheat steam temperature, a reheat steam temperature control strategy for the 1 000 MW double-reheat ultra-supercritical unit is proposed and illustrated from the aspects of the boiler heating surface arrangement, the swinging burner nozzle, the flue gas damper, the micro water spray desuperheaters and emergency water spray desuperheaters for both the primary and the secondary reheaters. Then the structure of the primary and the secondary reheater steam temperature control circuits of a 1 000 MW unit is presented with the superheat and reheat steam temperature decoupling method also being introduced. The practical operation has proved that this control strategy has good application effects.

Optimization on the Logic of Fast Valving System of Ultra-Supercritical Unit of Shanghai Turbine Company

FAN Yinlong, ZHANG Bao, LI Wei, DING Yangjun, GU Zhenghao

2017, 50(9):  143-147.  DOI: 10.11930/j.issn.1004-9649.201705050

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In order to guarantee the stability of the power system, fast valving is usually set up for turbine units, which can effectively avoid unit tripping during the transient fault of power grids. However, tripping accidents caused by the misoperation of the fast valving system during the transient fault of power grids have occurred in many units in recent years. In this paper, with the discussion of several such accidents and taking a 660 MW ultra-supercritical unit made by Shanghai Turbine Company as an example the fast valving model is established and the fast valving logic is analyzed. To improve the reliabilities of the fast valving system, the time delay and the speed quantitation are added to the original logic judgment to carry out simulation for the logic optimization. The simulation results show that the optimization can make the fast valving system work better and avoid its malfunction at the same time, ensuring the safe operation of the units.

Study on the Reliability Evaluation System for the Auxiliary Equipment in the Thermal Power Plant

BAI Ling, CHEN Hangjun, LI Shi, ZHAO Zhenning, SUN Zhichun

2017, 50(9):  148-154.  DOI: 10.11930/j.issn.1004-9649.201703085

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The reliabilities of the auxiliary equipments in thermal power plants are the major factors that affect the safety of the units. Therefore, it is important to establish an evaluation model to improve the management of the equipments. There are various and correlative indicators with cause-and-effect and subject relationships to evaluate the reliabilities, such as frequencies and times. In this paper, with the combination of the analytic hierarchy process(AHP) and the fuzzy comprehensive evaluation(FCE), the multi-level comprehensive evaluation model and system consisting of the goal level, the management level and the equipment level are established and the overall, precise and comprehensive quantitative assessment is obtained. In addition, the rationality of the model is verified by the practical evaluation on the 186 auxiliary equipments of 12 units from 4 power plants.

Cause Analysis of Main Steam Piping Explosion in a Coal-Fired Power Plant

SUN Zhongyuan, QIU Yunlin

2017, 50(9):  155-160.  DOI: 10.11930/j.issn.1004-9649.201612024

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Regarding the main steam pipe explosion accident that occurred in a power plant, the analysis on the failure of the main steam pipe is conducted by means of the combination of macro structural stress analysis and microscopic study. Several related factors, such as piping mechanics, component structure, material component, metallographic structure, piping mechanical property, and section analysis, etc are also taken into account. The result shows that the unsuitable base metal and mismatched welding material are the major causes of the explosion. In addition, there exist some other severe defects in the weld joints such as cracks and blowholes. From the result it is pointed out that the safety testing of the power pipeline has to be enhanced to remove the potential safety risks and avoid such problems happening again.

Determination of Three Antioxidants in Turbine Oil by GC-MS Method

MENG Weixin, WANG Hongmei, QIAN Yihua, ZHANG Li

2017, 50(9):  161-164.  DOI: 10.11930/j.issn.1004-9649.201707063

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It is of great importance to determine antioxidant contents in the study of turbine oil antiaging. In this paper, methanol is selected for oil sample extraction. By using gas phase chromatography-mass spectrometry(GC-MS), the method to measure three antioxidants simultaneously and quantitatively in turbine oils, i. e., 2, 6-Di-tert-butyl-4-methylphenol(T501), N-Phenylnaphthalen-1-amine (T531) and 4, 4'-dioctylphenylamine (DODA), is established. The accuracy and precision of the method are also studied, and the analysis of the actual samples is carried out. The study results show that the recovery rates of the three antioxidants are between 95.8% and 101.2% with the relative standard deviation less than 1.04%. Particularly, the method is suitable for fast determination of the three antioxidants in turbine oils owing to its ease to use in sample treatment and analysis. The successful development of this method can also provide a new way for the determination of other additives in turbine oils.

New Energy

Optimal Control Strategy of Quick Response of Large Direct-Drive Wind Turbine

MENG Jie, PAN Qiaobo, GAO Qingshui, DENG Xiaowen

2017, 50(9):  165-170.  DOI: 10.11930/j.issn.1004-9649.201606039

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Because of large system inertia in high capacity wind power turbines, it is difficult to respond quickly to controls. Based on wind turbine characteristics and PMSM mathematical model, a non-linear affine model is established for wind power system. A system speed control strategy is proposed by using differential geometry principle and feedback linearization theory. A load torque forward compensation method is introduced to form a rapid response control strategy with easy physical implementation. Compared with traditional vector control stagey and voltage decoupled forward compensation strategy, the simulation results show the effectiveness of proposed method in large capacity wind turbine quick control response.

Research on Peer to Peer Control Strategy for Microgrid Based on the Improved Power Loop

WANG Lingyun, ZHOU Xuanqing, LI Sheng, LIU Yuan

2017, 50(9):  171-177.  DOI: 10.11930/j.issn.1004-9649.201611006

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To overcome the defect of traditional droop control method, a peer to peer control strategy for microgrid based on improved power loop is proposed. The proposed strategy can also reduce dependency of microgrid on communication system and realize plug and play for distributed generators (DG) and loads. In order to solve bus voltage amplitude and frequency deviation problem caused by traditional droop control method, a compensation unit of voltage amplitude and frequency is introduced and an improved feedback controller of power loop is established. Taken a microgrid composed by two DGs with same capacity as example, simulation results using the traditional and proposed schemes are compared and analyzed. Microgrid operation characteristics are analyzed respectively in two operation modes: grid-connected/islanding operation switching mode and load switching mode. The simulation results indicate that proposed control strategy can reduce bus voltage amplitude and frequency deviation effectively.

Rotor Current Increment Analysis of Doubly-Fed Induction Generator During Symmetrical Faults Before Crowbar Protection Trigger

WANG Yijun, LEI Yang, SHEN Qingkun

2017, 50(9):  178-184.  DOI: 10.11930/j.issn.1004-9649.201607056

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It is important to analyze rotor current increment characteristics quantitatively for doubly-fed induction generators(DFIG) initiated by terminal voltage symmetrically dip for wind farm planning, relay protection configuration and cascading trip-off risk reduction. Under conditions of constant rotor speed, excitation voltage in early phase, the electromagnetic transient process of DFIG before crowbar protection triggered is analyzed in detail. By using superposition principle, a maximum rotor current increment calculation method for DFIG initiated by terminal voltage dip is proposed. Furthermore, analytic model to calculate maximum increment of rotor current for DFIG initiated by terminal voltage dip without consideration of stator and rotor winding resistance is derived. Calculating results of different kinds of generators are within 10% error margin compared with iterative calculation results, which show effectiveness of proposed analytical method.