Table of Content

05 March 2019, Volume 52 Issue 3

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Research on Key Issues of Energy Storage Development and Application in Power Systems

YUAN Bo, ZHANG Yunzhou, LU Gang, XU Zhicheng, WANG Peng, YANG Jie

2019, 52(3):  1-8.  DOI: 10.11930/j.issn.1004-9649.201902018

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With the maturity of energy storage technologies and rapid decline in cost, China's energy storage industry has developed rapidly, and the application of energy storage in power systems has gradually shifted from demonstration to commercialization phase. However, the energy storage industry is still in its early stage of development, and some problems still exist, such as the unclear development prospects, the unperfected standard systems, and the ill-defined business models and market mechanism. This paper reviews the status quo of China's energy storage development from the aspects of development scale, technological economy and industrial chain. Based on the coordinated planning theory of "generation-grid-load-storage", the prospect of medium and long term energy storage development are investigated from the macro layer, and relevant important issues are studied, such as the rational operation mode of energy storage and its relationship with new energy accommodation. And the key application issues of energy storage in generation side, grid side and user side are analyzed from the microscopic aspects, and related development strategies are studied. Relevant suggestions are put forward to provide support and reference for promoting the healthy development of China's energy storage industry.

Analysis of Key Points on Curbing Colored Plume in Coal-Fired Power Plants and Environmental Management

MO Hua, ZHU Jie

2019, 52(3):  10-15,35.  DOI: 10.11930/j.issn.1004-9649.201812027

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Based on the study of relevant domestic and foreign standards and by taking account of the current development status of flue gas treatment technologies in coal-fired power plants in China, the concepts, interrelations and distinctions between filterable particulate matters, condensable particulate matters (CPM) and dissolved solids in flue gas are analyzed. It is pointed out explicitly that the colored plume environmental management plays the key role in coal-fired power plants in curbing the condensable particulate matters as represented by SO₃. Then, the existing problems in the present environmental management policy regarding colored plume control are sorted out, and finally corresponding policy suggestions for CPM environmental management are put forward.

Technical Route Selection and Economic Analysis on Wet Plume Treatment for Coal-fired Units

LIANG Xiujin, ZHU Wentao, WEI Hongge, ZHU Yue

2019, 52(3):  16-22.  DOI: 10.11930/j.issn.1004-9649.201901107

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Regarding the multiple available solution strategies for wet plume treatment, systematic thermodynamic calculation has been carried out for a 300 MW unit in this paper. The dominant factors are then studied together with the economic analysis. Calculation results for the thermal system show that if conditions permit, lowering down the flue gas temperature before desulphurization can reduce net gas temperature and humidity effectively. In addition, reducing the circulating cooling water temperature at the flue gas condensing heat exchanger turns out to be the most effective way to reduce heat exchange area. Alternatively increasing the cooling water volume is another efficient way. Through economic analysis, it is discovered that equipment depreciation and electricity consumption account for a larger proportion of production cost increments, while the unit utilization hours and water pricing are important contributors to operation and maintenance cost of the reconstruction project. As far as conventional units are concerned, the extra cost per unit MW generation is around 2.5~4.5 yuan/MW incurred by renovation project of wet plume elimination.

Study on the Behavior of Sulphur Trioxide in the High-Sulphur Low-Temperature and High-Ash Flue Gas Environment

ZHANG Zhixiang, LI Nan, ZOU Xiaogang, SU Lin, LI Wenfeng, LI Weitao, HAN Jianping, XU Dangqi

2019, 52(3):  23-28.  DOI: 10.11930/j.issn.1004-9649.201812024

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A low-low temperature economizer test-bed is set up in a generation unit burning high-sulphur coal, and the SO₃ co-removal experiment is carried out in the high-sulfur, low-temperature and high-ash flue gas environment. The results show that the ratio of SO₃ to SO₂ concentrations is about 0.97%, and the SO₃ concentration at the outlet of the low-low temperature economizer drops significantly when the flue gas temperature falls into the range of 150~120℃. By contrast, when the temperature is below 120℃, no significant change of SO₃ concentration is seen with the temperature decrease, which can be kept below 15 mg/m³. While with the temperature of flue gas below 100℃, the SO₃ concentration is basically stabilized at about 10 mg/m³. Especially when the temperature of flue gas decreases to around 100℃, the removal rate of SO₃ is 84.3%~88.8%. Moreover, the measured SO₃ concentrations do not match well with calculated values from the formulas of acid dew point. When the temperature of flue gas is above 150℃, the measured data is apparently lower than the calculated value, while with the temperature below 115℃, the measured value is apparently higher than the calculated value. The change of SO₃ concentration in the low temperature flue gas of high sulphur coal is subject to the flue gas temperature and the fly ash. The empirical formula obtained through this experimental study can effectively forecast the SO₃ concentrations in flue gas.

Collaborative Removal of SO₃ and Hg by Electrostatic-Fabric Integrated Precipitator

CHEN Kuixu

2019, 52(3):  29-35.  DOI: 10.11930/j.issn.1004-9649.201812056

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Featured by long-term stable dust emissions, high adaptability to varieties of coal, low investments, less land occupation and low maintenance costs, the electrostatic-fabric integrated precipitator (EFIP) technology has been widely used in coal-fired power plants in China in recent years. The removal efficiency of SO₃ by EFIP exceeds 60%, which can be boosted to more than 80% after spraying a small amount of alkaline adsorbent. The removal efficiency of Hg^P by EFIP exceeds 99%. As for gaseous and total amount of mercury, though affected by the distribution of mercury in flue gas, the removal efficiency of gaseous mercury can still be improved to over 90% after spraying the adsorbents. Compared with other pollutant removal equipment, EFIP has obvious advantages in its high efficiency and low cost for collaborative removal of gaseous pollutants such as SO₃ and Hg.

Techno-Economic Analysis on Comprehensive SO₂ and Dust Treatment Technologies of 600 MW Coal-Fired Units

ZHANG Zhizhong, ZHANG Yang, DU Zhen, PEI Yukun, XU Ketao, ZHU Yue

2019, 52(3):  36-42.  DOI: 10.11930/j.issn.1004-9649.201807098

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In view of the requirements of ultra-low SO₂ and dust emission in coal-fired power plants, the currently widely-used technologies of high-efficiency desulfurization, collaborative dust removal of desulfurization system and wet electrostatic precipitator have been briefly described. Taking the example of ultra-low SO₂ and dust emission renovation in 600 MW units burning coal with high sulfur and high ash content, the techno-economic assessment has been performed to study the scheme of double-tower double-cycle collaborative desulfurization and dust removal (i.e. scheme one) and the scheme of double-tower double-cycle design equipped with wet electrostatic precipitator (i.e. scheme two) in terms of technical parameters, engineering work load, adaptability, investment expense and the cost of operation. The comparison result shows that the scheme one comes with less renovation engineering work load, maintenance work load or additional auxiliary power consumption of power plant, while scheme two has advantages over scheme one in the aspects of the adaptabilities of unit load and inlet dust concentration, the physicochemical property sensitivities of dust and the operation stability. Although the total investment expense and the cost of operation and maintenance of scheme two are higher than those of scheme one, scheme two is capable of promoting further collaborative SO₃ removal and contributing to eliminating the issue of blue smoke plume.

Experimental Study of the SO₃ Detection and Collection Efficiency in Coal-fired Flue Gas

CHEN Weixiang, GUO Jun, YE Xinglian, LIU Xiyao, CHEN Yongqiang, ZHENG Fang, GONG Guohan

2019, 52(3):  43-48.  DOI: 10.11930/j.issn.1004-9649.201901088

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Because of the low concentration and active chemical properties, it has always been difficult to detect SO₃ in the coal burning flue gas for pollutant inspection domestically and abroad. Aiming at the problem of the low collection efficiency of SO₃ detection by control condensation method, the experiment was conducted based on the homegrown SO₃ calibration system. Study results show that:the collection efficiency can be effectively improved to over 90% through the application of the D-type condenser and filter membrane filter device with borosilicate glass fiber membrane, if the optimal sampling flow rate was kept at 20 L/min, and the heating temperature of sample tube, condenser pipe and filter was controlled precisely. Hence both the collection efficiency of SO₃ detection and the accuracy of test result are guaranteed. The enhanced control condensation method has been widely used in computer simulations under the conditions of low dust content with certain moisture and various concentrations of SO₃, and consequently can be implemented to examine the SO₃ concentration in fume for the entire coal-fired power industry.

Feasibility Analysis on the Application of SO₃ Removal Technology in Coal-fired Power Units at Low Load SCR Operation

HU Dong

2019, 52(3):  49-55.  DOI: 10.11930/j.issn.1004-9649.201806086

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In order to meet the requirement of the flexibility reconstruction projects in coal fired power plants, it is necessary to ensure the safe and stable operation of the units at low load. The low load SCR denitration is an important part of the flexibility reconstruction project. This paper analyzes why SCR reactor exits when the coal-fired boiler operates at low load, reviews the development of the SCR technology under full load, and introduces some typical retrofitting schemes to improve the adaptability of SCR at low load. These retrofitting schemes are compared with the original design from the aspects of initial investment, retrofitting schedule, effectiveness and other benefits. The specific situation of the plants or units should be considered as well. In addition, the alkaline sorbent injection technology is more practical in engineering, as it has some other benefits such as curing plume visibility, preventing the APH plugging, resolving equipment corrosion, reducing the desulfurization waste water and synergistic removal of heavy metals.

Site Selection for Reactive Power Compensation of Multi-Infeed HVDC systems

LEI Qian, BAO Wei, QU Haini, XU Tangyun

2019, 52(3):  56-60.  DOI: 10.11930/j.issn.1004-9649.201804001

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Reactive power compensation is one of the effective means to improve voltage stability. The reactive power compensation problem of multi-infeed HVDC systems is more complex as the conventional voltage stability index can not effectively represent the relation between voltage and power of multi-infeed HVDC systems. The multi-infeed voltage stability index (MVSI) is proposed for judging the voltage stability of multi-infeed systems, which is based on multi-infeed interaction factor(MⅡF), node weight and time domain analysis. Furthermore, a site scheme is proposed for reactive power compensation. Firstly, the voltage weak areas are identified with the help of critical impedance. Then, the priority compensation node is selected on the basis of voltage weak areas and MVSI. The simulation results proved the validity and accuracy of the index.

Evaluation of Electric Power Replacement Considering Spatiotemporal Characteristics of Power Source Structure

ZHANG Xinhe, SONG Yang, HUANG Wei, QU Bo

2019, 52(3):  61-67,119.  DOI: 10.11930/j.issn.1004-9649.201804032

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The existing evaluation method for demand-side management energy-saving cannot quantify the energy-saving produced by the change of the energy types of the terminal equipment, and the traditional electric power replacement evaluation method cannot take into account the influence of the real power source structure based on the power network flow. An energy-saving and emission-reduction evaluation model is established, which takes into account the power network, power source structure and electricity use mode. The energy consumption coefficient of electricity (ECCE) and coal consumption coefficient of electricity (CCCE), which characterize the energy consumption level of the power system, are proposed and deduced. The energy saving and emission reductions of electric power replacement project are quantified from the perspective of whole process based on generalized energy saving. The spatiotemporal characteristics of ECCE and CCCE are studied through case study, and a typical scenario database is established. Through demonstration of electric vehicle (EV), the operation of electric power replacement project optimized through demand response and energy storage has positive impact on evaluation index.

An Integrated Analysis Method for Wind & Solar Power Accommodation Based on Peak Regulation Balance Principle

ZHANG Jinfang, LI Nan, LIU Jun, MI Zhe, YUAN Bo

2019, 52(3):  68-72.  DOI: 10.11930/j.issn.1004-9649.201706004

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The coordinated development of wind and solar power has become the focus of China's renewable energy development in the current and future. Based on the principle of system peaking regulation balance, and with combination of the statistical characteristics of wind power and solar power output characteristics, an integrated analysis method is proposed for accommodation of wind and solar power. By firstly determining the installed capacity of wind power through system power balance for the night peak load period in a typical day, and then figuring out the installed capacity of solar power through system power balance for the midday peak load hours, the proposed method effectively solves the problem of uncertainty for the conventional peak regulation balance method, which determines the combined installed capacity of the wind and solar power through peak regulation surplus. The simulation results have validated the effectiveness of the proposed method.

Research on the Optimal Maintenance Cycle of Redundancy Protection Based on Hierarchical Markov Model

CHONG Zhiqiang, CHEN Peiyu, MA Shiqian, YU Guangyao, WANG Xudong, LI Guodong, GUO Yue

2019, 52(3):  73-80.  DOI: 10.11930/j.issn.1004-9649.201711285

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In order to solve the problem of numerous states in assessing the reliability of the redundant configured protection system based on Markov method, a hierarchical Markov model is presented. In the process of establishing Markov state space, the states of the protected device and protection system are divided into several layers according to their existing states. And then each layer is further divided into detailed states. Finally, a typical transmission system protection system is used to verify the proposed reliability model, and the optimal maintenance cycle is solved by this model. The results show that excessive maintenance and insufficient maintenance are both unfavorable to the reliability of the protection system. The redundant protection system is better than the single configured protection system in reliability, and has longer optimal maintenance cycle. The main factor that affects the optimal maintenance period of relay protection is the reliability of relay protection and have little relationship with the reliability of the protected equipment. This method can solve the problem of missed states in the process of state division.

Simulation Analysis of Power System Voltage Regulator Based on PSCAD

CHEN Xinqi, QIN Ganghua, YANG Min, ZHAO Lihang, CHEN Rong, XIE Geshang

2019, 52(3):  81-86,139.  DOI: 10.11930/j.issn.1004-9649.201809061

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The high-voltage bus stability of power plants is critical to the stability of the power system. Attaching a power system voltage regulator (PSVR) to the control system can improve the effective dynamic reactive reserve capacity of the generators, and improve the stability of the high-voltage bus of the power plants. Based on the control principle and mathematical model of PSVR, this paper analyzes the current compensation effect of PSVR to compensate for a portion of the transformer impedance. Based on an actual application demonstration project of PSVR, a detailed simulation model of the PSVR research system is built based on the power systems computer aided design (PSCAD) to simulate various disturbances such as power grid accident, impact load, and reactive voltage fluctuation, and the role of PSVR in improving reactive power support of power system is examined and verified. The simulation results show that the PSVR can make full use of the potential reactive capacity of the generators, improve the reactive response speed of the generators, restore the transient voltage faster, and improve the supporting function to the high bus voltage stability of the power plant.

Evaluation Method of Black Start Scheme with Anti-reverse Order and Weight Adaptive

YAO Liyi, LUO Pingping, XIANG Yinxing, LIN Jikeng

2019, 52(3):  87-94.  DOI: 10.11930/j.issn.1004-9649.201807063

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The TOPSIS method is widely used for its simple and easy implementation, but it has the reverse order problem and can not reasonably consider the index weight. To solve this problem, a new evaluation method of black start scheme with anti-reverse order and weight adaptive determination is proposed. Firstly, this method introduces the positive and negative extreme scheme and the improved data normalization method, which overcomes the reverse order problem of TOPSIS; and then it proposes an index weigh adaptive determination method, which not only takes full consideration of the preference of experts, but also makes the objective information be fully utilized. Based on the above improvement strategy, a new TOPSIS method with anti-reverse order and weight adaptive determination is proposed, and the specific implementation steps are provided. The example of black start in Hebei south network has proven the effectiveness of the proposed method.

Optimum Research of Suspension String on Ultra High Voltage Transmission Line

NIU Haijun, SI Jiajun, ZHOU Lixian, ZHU kuanjun, LIU Shengchun, ZHU Xiaoqiang, SHI Xiaolong

2019, 52(3):  95-101.  DOI: 10.11930/j.issn.1004-9649.201804046

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The length of triple suspension insulator string adopted in the UHV projects is always so long that it may result in the waste of engineering investment. In this article, so as to solve the problems mentioned above, the optimum design of the three-variable-two plane, triangle joint plate and hanging plate in suspension string was carried out based on the experience in design, manufacture, construction and operation of fittings used in ±800 kV UHVDC projects and 1 000 kV UHVAC projects. It is proposed that the three-variable-two plate in the three-wire clip suspension string should be placed on the low-voltage side and the original fittings at high voltage side should be replaced by the connection of the single-plate triangle plate and the double-plate triangle plate. Thought the careful simulation analysis of the mechanical characteristics and electrical characteristics of the proposed, as well as the real-model corona characteristic test research, the compact triple suspension string and matching fittings for the 1 000 kV projects were successfully designed. The total length of the insulator string can be reduced about 600 mm which can improve the economic benefit obviously.

Research on Streamer Discharge Simulation and Synergistic Effects of SF₆/N₂

LI Xuebin, LU Xuchen, LI Bin, ZHENG Geling, LI Xintao, GENG Zhenxin, SHAN Changwang, LIN Xin

2019, 52(3):  102-108.  DOI: 10.11930/j.issn.1004-9649.201801176

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A two-dimensional fluid model is set up in this paper to depict the kinetic characteristics of particles in gas discharge process. The finite element method and flux corrected transport method are used to solve the model and to get the features of discharge rules for 50%SF₆+50%N₂ in uniform electric field, simulate distributions of electron number density in streamer process, and the effects of charged particle on uniform electric field are analyzed. A gas discharge experimental platform is established to measure the breakdown voltages of SF₆/N₂ mixtures with the lower insulation gap of plate electrode at 5 mm, and the influences of mixing ratio and gas pressure on SF₆/N₂ synergistic effect are studied by comparing experimental values with calculated values. The results show that the electron number density increases with streamer moving to anode, and that the influence of space charges on electric field is small in initial phase while obvious electric field distortion will occur with the increase of electric charges. The experimental breakdown voltage of SF₆/N₂ gas mixtures is larger than the calculated one, and their difference becomes smaller with the increase of SF₆ content, which means that the synergistic effect of SF₆/N₂ is obvious when the SF₆ content is small while the effect will be weakened when the SF₆ content is high.

Conditional Maintenance of Coal-Fired Power Generation Equipment Based on Early Fault Warning System

YANG Qin, ZHANG Zhenwei, YANG Mo, DONG Yuming, ZHANG Hongsheng

2019, 52(3):  109-114.  DOI: 10.11930/j.issn.1004-9649.201808103

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The state-based maintenance is by far the most advanced maintenance mode with the development of condition monitoring technology. Since the 1990s, the state-based maintenance of power generation equipment has been implemented in China, but with very few remarkably successful cases. In order to practically implement the state-based maintenance of power generation equipment, a power generation group has introduced, developed and popularized an early fault warning system based on similarity modeling technology for the power generation equipment since 2008. This paper introduces the mechanism of the system, and illustrates how the early fault warning system was effectively applied in the state-based maintenance of coal-fired power generation equipment with the case studies in steam turbine, boiler, electrical elements and chemical elements, respectively. At last, some suggestions are put forward on how to integrate them in a better way.

Research and Application of Expanded Unit Element System in Circulating Water Drainage System for Coal Fired Power Plant

YU Bo, MING Jianpu

2019, 52(3):  115-119.  DOI: 10.11930/j.issn.1004-9649.201711013

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Higher than designed water temperature at the outlet of the natural draft cooling tower will seriously affect the economic efficiency of the unit. In order to solve such problem in Heyuan power plant, the amount of circulating water into the cooling tower was first reduced. Then by taking account of the current situation of more frequent standby dispatch whereas more hours of operation for a single unit, this paper demonstrates and implements the expanded unit system transformation of the circulating water drainage system, in which the circulating water were diverted to two cooling towers for heat exchange and cooling. The experimental results show that the amount of water entering each cooling tower decreases significantly while the operation of the circulating water system is still safe and controllable after the expansion of the unit operation of the recirculating water drainage system. Under various typical operating conditions, the condenser back pressure decreases by 0.42~0.96 kPa. Particularly, the higher the unit load, the more the circulating water volume and the more significantly the condenser back pressure decreases. Therefore, the economy of the unit operation is greatly improved.

Cycle Pump Optimization Management System for CCGT Power Plants

HUANG Zheng, SHU Jianjun, YU Guoqiang, SI Fengqi, ZHOU Jianxin

2019, 52(3):  120-126.  DOI: 10.11930/j.issn.1004-9649.201803048

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Aiming to address the lack of cycle pump management in CCGT power plants, a cycle pump optimization management system for CCGT power plants is developed. Based on the optimization model, the system can adjust the pump operation mode, according to the change of the unit load, heating quantity and the weather conditions, to realize the optimized operation of the pump. The system also builds the unit characteristic database, which facilitates the model modification and maintenance after the unit maintenance. The system has been applied in a 200 MW combined cycle unit successfully, which is positive on reducing auxiliary rate, promoting energy saving and consumption reduction, and improving the economy of the unit. The successful practice demonstrates its broad application prospects.

Application Research of Intelligent Security System in Thermal Power Plants

HAN Chao, MA Xinxin, SHEN Weichun, DONG Shibo, WANG Xiuna, CAO Xu, XU Jianfeng

2019, 52(3):  127-132.  DOI: 10.11930/j.issn.1004-9649.201802082

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In view of the growing security requirements in the operation of current thermal power plant, the construction of intelligent security system and the application of intelligent equipment and information technologies have become the up-to-date development trend of safety monitoring and management in thermal power plant so as to ensure the maximum security and reliability of the operations as well as the safety of personnel at the workplace. By identifying major hazard sources and analyzing requirements of safety monitoring and management upgrade, the overall framework and application functionalities of intelligent security system are presented on account of requirement analysis result. Further analysis and research are conducted and elaborated regarding the application and its practical value appreciation with new intelligent security technologies for major hazard sources. Meanwhile suggestions on maintaining the advancement of intelligent security system are also provided.

Applied Research and Prospect of Big Data in Power Plant Intelligence

WANG Zhongjie, WEN Le, YANG Xinmin

2019, 52(3):  133-139.  DOI: 10.11930/j.issn.1004-9649.201705013

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Big data is a hot topic in industry and information technology. With the progress on the research of intelligent power plants and the development of big data technology, the big data technology has broad prospects in intelligent power plant application. The purpose of this paper is to study the framework of big data and its future application prospects in the field of power generation. The status of big data technology development, and the relationship between big data, cloud computing, and intelligent power plants are analyzed and elaborated in this paper. The framework of big data technology for intelligent power plants is proposed, and the prospects of big data in intelligent power plant application is forecasted. In the future, intelligent power plants will be an important field for big data application.

Comprehensive Utilization of Resin Regenerating Wastewater in Zhuhai Power Plant

LI Yuyu, WU Huoqiang, YU Weiquan, MAO Jin, LIAN Kunzhou

2019, 52(3):  140-145.  DOI: 10.11930/j.issn.1004-9649.201711210

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Regarding the problem of excessive ammonia nitrogen content in reclaimed wastewater of condensate treatment system in Zhuhai power plant, three kinds of comprehensive utilization programs, i.e., membrane absorption, reverse osmosis concentration-electrolysis and ammonia stripping-phosphoric acid absorption-reuse to slag water system, were put forward and a thorough comparative study was carried out on the basis of the investigation of water quantity and water quality characteristics and the analysis of ammonia nitrogen discharge of the whole plant wastewater. The results show that after the removal of most ammonia nitrogen in the regenerated wastewater through the process of blowing and absorption, the comprehensive utilization scheme that reuse this part of the wastewater to the slag water system is the most feasible solution with low investment and operating costs while the application techniques are mature and reliable. Meanwhile, phosphoric acid solution is used to absorb ammonia tail gas to produce useful fertilizers without secondary pollution. The scheme was adopted by Zhuhai power plant and implemented in 2018. The actual operation effect is satisfactory. After the operation into service for nearly half a year, the average concentration of ammonia nitrogen from recycled wastewater was reduced from 280~420 mg/L to 30~60 mg/L, and the removal efficiency was over 85%, which exceed the requirements of design specifications.

Applicability Analysis on the Structure Model and Numerical Model for the SCR System

XIAO Yujun, ZOU Yihui, LI Caiting, ZHOU Xuebin

2019, 52(3):  146-152,160.  DOI: 10.11930/j.issn.1004-9649.201803006

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The accuracy and adaptability of the structure model and numerical model were discussed scantly in the numerical calculation for the thermal power plant SCR system. Therefore, in this paper both the complete and the partial structural models were established based on the structural characteristics of the typical SCR system, then simulated using the Fluent software with standard κ-ε turbulence model and Realizable κ-ε turbulence model. Through the comparison of velocities between the simulation and experiment results, the impacts of the turbulence model and the economizer export, the ash hopper, the AIG and the uniform flow grille pattern on the calculation accuracy of flue gas flow field were analyzed. Similarly, by comparing the simulation and experiment results regarding the pressure drops, the NO_x concentration distribution and NH₃ escape distribution in the outlet flue, the method correctness and validity of parameter setting in the porous medium model as well as the multi-component reaction model were also demonstrated respectively The results showed that the economizer export structure and the AIG structure had significant impacts on the calculation accuracy of the flue gas flow field in the inlet flue. The relative error between the simulated and experimental pressure drop across single layer of catalyst was -1.9%. The NO_x removal efficiency of simulation and experiment were 79.35% and 80.56%, respectively with the relative error -1.5%. The NH₃ escape distribution trends of the simulation and experiment result were consistent as well.

Comprehensive Diagnosis and Closed Loop Optimization of NO_x Ultra-Low Emission of SCR

YANG Xigang, JIN Baosheng, XU Yueyang

2019, 52(3):  153-160.  DOI: 10.11930/j.issn.1004-9649.201808126

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In view of the typical problems in the flue gas denitration system, such as poor flow uniformity, ammonia escape, air pre-heater clogging, failure of NO_x stable ultra-low emission in full load section, a comprehensive diagnosis and closed-loop optimization strategy for ultra-low emission of SCR is proposed. Combining with the 630 MW implementation case, with the online large data and performance testing as the base, numerical simulation and system diagnosis as the means, by means of simulation evaluation and test analysis, the improvement scheme is put forward, optimized, revised and implemented, and finally combined with the performance test to verify the effect. The comprehensive diagnosis and closed-loop optimization of the SCR system are performed with multiple means. Comparing before and after modification, the standard deviation of NO_x concentration field decreases from 18.6% to 4.89%, the denitration efficiency increases from 86.7% to over 89%, and the chimney NO_x emission concentration is steadily below 50 mg/m³, the ammonia escaping mass concentration at the outlet of the SCR system decreases from 16 mg/m³ to 0.75 mg/m³. The effect of ultra-low emission reconstruction is remarkable.

A Planning Model for Hybrid Hierarchical Communication Network of Transmission Line Online Monitoring

YU Bin, YIN Xianggen, WU Xiaozhong, TANG Jihong, NING Chunhai, LI Hui, ZHU Weijun, LIU Haifeng, XU Hao

2019, 52(3):  161-168.  DOI: 10.11930/j.issn.1004-9649.201805036

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In order to solve the problems of bandwidth bottleneck and high latency in chain-type wireless communication network of transmission line online monitoring, a hybrid hierarchical communication network planning model and the corresponding multi-objective decision-making method are proposed. A network planning model of fiber-optic separation tower placement is formulated with objects of placement costs and end-to-end latency optimization, while satisfying the constraints of graph-based path connectivity and bandwidth. Particle swarm optimization algorithm is used to solve the model, so as to obtain the Pareto optimal solution set. The most satisfactory network planning scheme is selected by the multi-attribute decision-making method based on fuzzy entropy weight of vague set. Finally, the effectiveness of the proposed model and algorithm is validated by results of the case study. Besides, the impacts of the subjective weight, the data rate and network scale on the decision-making are analyzed.

Development and Application of Partial Discharge Detection Robot for High Voltage Switchgear

LUAN Yiqing, LI Jianxiang, LI Chaoying, HUANG Rui, LYU Juntao

2019, 52(3):  169-176.  DOI: 10.11930/j.issn.1004-9649.201803120

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Partial discharge detection of switchgear can only depend on manual operation at present, which has many problems such as large workload, low detection efficiency and poor detection quality. Aiming at above-mentioned problems, a robot is developed for partial discharge detection of switchgears. Based on the substation inspection robot, the newly developed robot is installed with a 5-DOF manipulator, uses binocular stereo vision technology to locate the detection position, and can carry multi-type sensors for automatically detecting the partial discharge state of the switchgears. The robot has been applied in the Ji'nan Mei Li Lake substation, and the results show that all the functions of the robot have reached the expected goals. The robot is of great significance for engineering application.

Research and Application of Intelligent Maintenance System Based on Internet of things and mobile Internet technology

WANG Liping, PANG Xiaoyan, ZHU Yu, LIU Xin, ZHAO Zihan, ZHANG Xufeng, DING Xiliang

2019, 52(3):  177-184.  DOI: 10.11930/j.issn.1004-9649.201803035

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This paper elaborates the intelligent maintenance methods of secondary equipment combining internet of things and mobile internet technologies, based on the state-of-art operation and maintenance of secondary equipment. An overall structure of secondary equipment intelligent maintenance based on internet of things and mobile internet technologies is developed, to realize the goal of intelligent identification, visual display and intelligent operation and maintenance of the equipment. In terms of technical schemes, the focus of this paper falls on the introduction of key technologies, such as intelligent identification, knowledge push, loop visibility, maintenance decision-making, auxiliary safety measures, which can effectively solve various problems in practice. It could create favorable conditions for the intelligent and information-based operation and maintenance of the secondary equipment, and improve the field equipment management level as well as the efficiency of operation and maintenance.