Table of Content

05 May 2019, Volume 52 Issue 5

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Innovative Theory and Methods for High-Efficiency and Flexible Power Generation of Ultra-supercritical Double-Reheat Coal-Fired Power Generation Unit

DUAN Liqiang, WANG Jing, PANG Liping, CHONG Daotong, YU Ji'an, DIAO Baosheng, LV Chunjun

2019, 52(5):  1-12.  DOI: 10.11930/j.issn.1004-9649.201903075

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Regarding the problems such as low economic performance and lack of flexibilities during the operations of double-reheat ultra-supercritical coal-fired power generation unit under frequent load change conditions, this paper studies the innovative theory and methods for high-efficiency and flexible power generation of ultra-supercritical double-reheat coal-fired power generation unit. Firstly, on the base of the specific fuel consumption method, the energy consumption distribution regularities of a traditional double-reheat coal-fired power generation unit under different load conditions are revealed. Then five types of new advanced double-reheat coal-fired power generation systems are proposed in this paper, which are all designed with the main steam temperatures of over 600℃ and more advanced capabilities of accommodating the peak load regulations, i.e., double-reheat power generation cycle integrated with the regenerative small steam turbine, double-reheat power generation cycle with the deep coupling between the boiler and turbine system, new double-reheat power generation cycle with CO₂ as the working medium, double-reheat power generation cycle with energy storage system and double-reheat power generation cycle integrated with the solar energy, respectively. Their ideas of integration and characteristics of these new cycle systems in improving the economic performance and operation flexibility are elaborated in details. The research results are illustrated as follows:boilers, steam turbines and regenerative heaters have great energy-saving potential; the standard coal consumption rate of the optimized double-reheat power generation cycle with the regenerative small steam turbine is 2.15 g/(kW·h) lower than that of the reference system; the coal consumption of double-reheat power generation cycle with the deep coupling between the boiler and turbine system can be reduced by 3.6 g/(kW·h) under THA condition; the coal-fired power plant with CO₂ as the working medium still has high efficiency even under load variation conditions; the double-reheat power generation cycle with energy storage system has better flexibility, while the double-reheat power generation cycle integrated with the solar energy has significant energy-saving potential, which can reduce coal consumption by as much as 14.73 g/(kW·h).

Simulation Study on the Dynamic Characteristics of a 660 MW Supercritical Coal-Fired Power Unit During AGC Processes

ZHAO Yongliang, DIAO Baosheng, HAN Xiang, LIU Ming, WANG Zhu, CHONG Daotong, YAN Junjie

2019, 52(5):  13-20.  DOI: 10.11930/j.issn.1004-9649.201903088

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Improvement of loading change rate in coal-fired power units is one of the key evaluation index of flexibilities in the power system during automatic generation control (AGC) regulating processes. In this study, the dynamic simulation models of a 660 MW supercritical reheat coal-fired power unit were developed with the detailed control systems embedded. Then, the dynamic characteristics of main thermal parameters at different loading change rate ranging from 75% to 100% THA were obtained. Taking the maximal fluid temperature deviation and average standard coal consumption rate deviation as the evaluation indexes, the security and economy of the coal-fired power units during AGC load change processes were analyzed. The results reveal that with the increase of loading change rate, the output power, main steam temperature and reheat steam temperature fluctuate more drastically. Besides, the maximal fluid temperature deviations increase gradually at water wall outlet, platen superheater outlet, horizontal low-temperature reheater inlet, and vertical low-temperature reheater outlet, which are 24.7, 29.1, 26.1, 41.3℃, respectively. The average standard coal consumption rate deviation decreases when the loading up rate increases, ranging from 2.35 to 2.53 g/(kW·h). On the other hand, the absolute value of average standard coal consumption rate deviation decreases when loading down rate goes up, ranging from -2.64 to -2.50 g/(kW·h).

Centralized Coordination Control of Ultra-supercritical Unit Based on Control-Constrained MIMO Predictive Control

ZHANG Jinying, SUN Jiguang

2019, 52(5):  21-28.  DOI: 10.11930/j.issn.1004-9649.201903089

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With the traditional control scheme the main steam pressure and the steam temperature of intermediate point cannot be regulated around the target settings when the load of the unit is changing, which will cause severe impacts on the security and efficiency of the unit operation. In this paper, the centralized coordination control scheme based on control-constrained MIMO (multiple input multiple output) predictive control is proposed to resolve the strong coupling and large time delay problems in the MIMO system without extra procedures of decoupling and feedforward. Firstly, the algorithm of control-constrained MIMO predictive control is explored and then prototyped using MATLAB. From the simulation results the centralized coordination control scheme demonstrated comparable tracking performance in power output to the traditional PID control scheme. Nevertheless it outperforms the latter scheme in the aspect of the tracking performance of the main steam pressure and the steam temperature of intermediate point as well as its robustness.

Assessment on the Threat to the Information Security of Power Plant Control System Based on SA-PSO-AHP Method

DUAN Xuchen, PENG Daogang, YAO Jun, ZHAO Huirong, XIA Fei

2019, 52(5):  29-35.  DOI: 10.11930/j.issn.1004-9649.201903085

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Due to the severe situation of information security in power plant control system, based on the information security evaluation of a power plant, a hierarchical progressive analysis model is established by using analytic hierarchy process (AHP) model. And then the consistency problem of judgment matrix is solved through the enhancement of particle swarm optimization (PSO) method in combination with simulated annealing (SA) algorithm, which can effectively overcome the drawbacks such as strong subjectivity and uncertainties in the current information security threat assessment. The practice in the thermal plant shows that this method can not only fully demonstrate the application of the fuzziness of the evaluation elements and processes, but also reduce the impact of individual subjective factors such that satisfactory evaluation results can be achieved.

Application of TDLAS on the Measurement of Temperature and Gas Concentration in Power Plant Boilers

CUI Qingru, LIU Miao, LI Xiongwei, LI Gengda, LI Yingbao, CHEN Baowei

2019, 52(5):  36-41.  DOI: 10.11930/j.issn.1004-9649.201903092

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On-line measurement of temperature and gas concentration distribution in power plant boilers is of great significance for controlling and optimizing the combustion process, improving the combustion efficiency and reducing the pollutant emissions. Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology has great application prospect for on-line measurement of temperature and gas concentration inside the furnace. Therefore, in this paper, the application of TDLAS technology is analyzed in the aspects of market demand, market obstacles, technical difficulties and economic returns, and then the critical problems to be resolved in industrial applications are explored. Overall, due to the relatively high costs of investment and maintenance, there have been few successful applications of TDLAS technology in China. However, it still has considerable potential for its future development.

Research and Application of Intelligent Centralized Management and Control System for Distributed Combined Cooling, Heating and Power Systems

HU Jing, YAO Jun, AI Chunmei, LI Yong, ZHANG Jun, QIU Yaming

2019, 52(5):  42-47,62.  DOI: 10.11930/j.issn.1004-9649.201808023

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This paper introduces the policy and industry background of distributed Combined Cooling, Heating and Power (CCHP) systems and intelligent platform construction. Further research and application of the intelligent management and control system is conducted for one of the National Energy Administration "Internet Plus" smart energy (energy Internet) demonstration project. The technical characteristics of distributed energy station are analyzed, then the overall design principles of centralized management and control system and functional planning are presented. The architecture of centralized management and control system and the application of intelligent technology, especially the key control technologies of the system are also summarized. Discussions regarding the practical application of intelligent technology in the centralized management and control system for distributed energy stations are put forward, which will provide the insights for the intelligent planning, construction and development in the field.

Forecast of Heating Surface Cleanliness of Coal-Fired Power Plants Based on PSO-Elman Neural Network

LI Qiang, SHI Yuanhao, ZENG Jianchao, CHEN Xiaolong

2019, 52(5):  48-53.  DOI: 10.11930/j.issn.1004-9649.201809054

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With the efforts intensified in energy conservation and emission reduction policies, great importance has been attached to the development and research of energy-saving and consumption-reducing technologies for thermal power plants from state level. Aiming at current unreasonable way of boiler blowing on the heating surface of the boiler, the pollution rate (FF) is used to characterize and represent the impacts of the cleanliness of the heated surface on the heat transfer of the boiler heating surface. The forecasting model of the heating surface cleanliness based on PSO-Elman neural network is established. Using the particle swarm optimization (PSO) algorithm in combination with Elman dynamic neural network, the Elman neural network structure is first determined according to the number of input and output parameters. Then by taking advantage of PSO algorithm the weights and thresholds of the neural network are optimized. Finally the derived optimal values and thresholds are assigned to the Elman neural network as the initial value for network training such that the heating surface cleanliness forecast model is established based on PSO-Elman neural network. Through simulations of specific examples, satisfactory forecasting accuracy is obtained and hence the effectiveness of the proposed method is verified.

Influence of Primary Frequency Regulation Parameters on Performance of a Ultra-supercritical Double Reheat Unit

WANG Zhu, HAN Xiang, XU Lihuan, ZHAO Yongliang, CHONG Daotong

2019, 52(5):  54-62.  DOI: 10.11930/j.issn.1004-9649.201903097

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Primary frequency regulation characteristics of double reheat unit have significant impacts on the operation stability and flexibility of power system due to its complicated flow process and large inertia. Based on the GSE simulation platform, the dynamic simulation models of the ultra-supercritical double reheat generation unit and primary frequency regulation were developed and validated by virtue of the combination of JTopmeret module and self-defined program. Then, the response characteristics of the thermal parameters in the double reheat unit during the primary frequency regulation process were studied. The effects of the load step amplitude and the speed droop on the primary frequency regulation characteristics were analyzed. It is discovered from the results that in the primary frequency regulation process of the double reheat unit, with step increase of the load power the real-time frequency will drop rapidly and DEH turbine control system will immediately take measures during dynamic processes, the real time frequency is less 50 Hz. Once the system reaches steady state, the relative change of flow volume and pressure of the primary and secondary reheat steam will be greater than those of the main steam. During the primary frequency regulation of the double reheat units, the increase of load step amplitude or the reduction of the speed droop, will both boost the dynamic overshoot of the frequency, and prolong the time duration for frequency regulation. Compared with single reheat generation units, the primary frequency control systems of double reheat units demonstrate faster response, whereas their maximum overshoot is larger during the regulation process.

Method for Parameter Identification of LV Distribution Network based on AMI Metering Data

WANG Xudong, WANG Gaomeng, LIN Jikeng, KANG Ning, DING Yi, LIU Hui

2019, 52(5):  63-69.  DOI: 10.11930/j.issn.1004-9649.201801029

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Aiming at the problem of poor identification of the line parameters in distribution network, this paper presents a method for identifying the line parameters in low-voltage (LV) distribution network based on advanced meter infrastructure (AMI). Starting from the nodes at the end of the network, the method estimates the branch line parameters of the network using the AMI measurement data. Nonlinear equations of the impedance parameters of the LV distribution line are established and the least square method is employed to solve the equations. In this way, the impedance parameter of all observable lines of the whole network can be identified and estimated. A case study has verified the feasibility and reliability of the proposed method.

The Effect of Excitation Characteristics of Electromagnetic Voltage Transformer on Ferromagnetic Chaotic Circuit

WANG Dongdong, TIAN Mingxing, ZHANG Huiying

2019, 52(5):  70-75,112.  DOI: 10.11930/j.issn.1004-9649.201806121

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In power system, the ferromagnetic chaotic circuit of electromagnetic voltage transformer (TV) may generate chaotic oscillations in some cases. The main reason is the magnetic saturation effect of TV core that leads to the non-linear change of inductance of core. In actual research, the excitation characteristic curve is often used to describe the nonlinear change of the TV core inductance. A fourth-order autonomous ferromagnetic circuit model with TV is introduced, and the influence of excitation characteristics of TV on ferromagnetic circuit is studied. Theoretical analysis and MATLAB simulation shows that chaotic oscillation exists in the circuit, and the nonlinear excitation characteristics of TV are the important factors that affect the chaotic dynamic behavior of the circuit.

Fault Direction Discriminating Element Used for the Distribution Network with ⅡG Integration

ZHU Yifan, ZHAO Hongcheng, CHEN Zhengguang, XU Chenjing, SUN Xiaojia, ZHANG Junjie, WU Hui, WANG Xingguo, WANG Wenhuan, ZHENG Tao

2019, 52(5):  76-82.  DOI: 10.11930/j.issn.1004-9649.201810022

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The access of DG (distributed generation) to distribution network makes the traditional radiant network with single generation become a complex network with multiple generations, which makes the phased current protection no longer suitable. Thus, it is urgent to renovate the original protections of distribution networks. However, due to the difference between DGs and traditional generators in structure and control method, the sensitivity of traditional directional components significantly decreases, which makes misjudgment even possible. In this paper, an adaptive direction discriminating element is proposed by taking the distribution network with ⅡG (inverter-interfaced generation) as an example. Firstly, the characteristics of short-circuit currents are distinguished by restricting the access position of ⅡG. Then, by setting the current setting value, the relay protections at different locations are classified and equipped with different logics of determining the direction of fault. Finally, according to the relationship between the short-circuit current and the setting value, the faults of positive and reverse directions can be distinguished.

Research on Passive Wireless Temperature Measurement System of High Voltage Isolating Switch Based on Pt Resistor

HE Yanmiao, LI Yujie, LI Zhibing, GAO Shan, YANG Jinggang, LI Hongtao, YANG Peng

2019, 52(5):  83-88,163.  DOI: 10.11930/j.issn.1004-9649.201711201

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The online temperature measurement technology is analyzed and verified in this paper based on power supplied by the inductive current and wireless communication technique combined with the structure and principle of disconnector, solving problems in the online temperature measure system such as wireless data transmission, sensor operating supply and equipment high reliability in an environment of high voltage and strong electromagnetic. The temperature distribution of disconnector contact is analyzed in this paper under different influential factors by means of numerical simulation calculation of temperature field and temperature rise test. Contact materials of various kinds, loop resistance in defect situation as well as the corresponding relation between loop resistance and contact temperature are designed in this paper. The temperature real-time monitoring technology with low cost and high efficiency is researched in this paper. Defects of abnormal heating are discovered in time, which is of great significance for ensuring the safe operation and improving power distribution reliability.

Outage Probability Evaluation of the Distribution Corridors Under Strong Typhoon Environment

CHEN Bin, YU Jilai

2019, 52(5):  89-95.  DOI: 10.11930/j.issn.1004-9649.201803213

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An outage probability evaluation method of distribution line under typhoon is proposed in this paper. First, the probability curve of the tower fault of the 10 kV distribution line is fitted according to the historical typical typhoon data. Secondly, the wind load in the area of the distribution network is simulated by the hydrodynamics software. Finally, based on the wind load calculated from the real-time meteorological information under real typhoon environment, the overall failure probability of the distribution lines are calculated. The simulation results verify the rationality and practicability of the method for the probability evaluation of the distribution network fault in the strong typhoon environment. The method can be used as a reference for emergency warning and disaster prevention of distribution network in southeastern coastal areas of China during typhoons.

Damage Causes and Anti-disaster Enhancement Measures of Western Hubei Power Grid

CAI Defu, SHI Tongqin, ZHOU Kunpeng, LU Shengwei, JIANG Wei, YAO Yao, CAO Kan, WANG Ying

2019, 52(5):  96-103.  DOI: 10.11930/j.issn.1004-9649.201707133

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Several large-scale and long-duration blackouts occurred in western Hubei power grid in recent years due to extreme natural disasters. A statistics is made of the damages of western Hubei power grid caused by natural disasters from 2008 to 2016, and the damage causes are analyzed from five aspects, including grid structure, design, equipment, construction, operation and maintenance. The anti-disaster enhancement measures are proposed for western Hubei power grid in terms of grid planning, design, equipment renovation, construction, operation and maintenance. The research results can provide an important reference for improving the anti-disaster abilities of power grid.

Hybrid Energy Storage DC Power Supply System Based on PSO-NM

ZHAO Xinxin, XIA Xiangyang, ZENG Xiaoyong, Li Xinhai, YANG Mingsheng, HUANG Zhi, WANG Zhixing

2019, 52(5):  104-112.  DOI: 10.11930/j.issn.1004-9649.201805113

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DC operation power source is commonly supplied by lead-acid batteries. This method is characterized by slow response speed to high-frequency equipment and environmental contamination. To deal with this problem, the paper proposes a novel hybrid DC power supply system, which consists of lithium batteries and super conductors. A novel energy management strategy, which uses the SOC feedback of the superconductor to limit the power output of the lithium battery, is also presented. The proposed energy management strategy, which is achieved by particle swarm optimization (initially proposed by Nelder Mead), can effectively reduce the instantaneous power output of the lithium battery, thus extending the life span of the equipment. The validity of the proposed approach is demonstrated and verified by Matlab/Simulink and field experiment. Experimental results suggest that the response speed is fast when the proposed strategy is adopted, thus indicating good reliability and engineering value.

Multiple Return-Stroke Characteristics for Positive and Negative Cloud-to-Ground Lightening of ±800 kV Binjin Line Corridor in Zhejiang Province

ZHOU Luyao, LI Te, WANG Shaohua, LIU Li, HU Wentang, ZHOU Xiangxian

2019, 52(5):  113-118.  DOI: 10.11930/j.issn.1004-9649.201805006

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In order to obtain the multiple return-stroke characteristics of positive and negative cloud-to-ground lightening in the corridor of the ±800 kV Binjin line in Zhejiang province, the statistical parameters of the 3 032 cloud-to-ground lightening samples monitored from June to September 2017 are statistically analyzed, including return-stroke times, cloud-to-ground lightening duration, return-stroke time interval, and return-stroke intensity. The multiple return-stroke parameters show obvious systematic variations with the return-stroke number, and the difference between positive and negative return-stroke characteristics is obvious. The statistical results show that the number of positive and negative lightening samples accounted for 27.57% and 72.43%, respectively. Single return-stroke account for 52.60% of negative lightening samples. The maximum number of return-stroke reaches 13, and the average number of return-stroke is 2.47. Single return-stroke account for 77.04% of positive lightening samples, and the number of return-stroke is relatively small. The maximum number of return-stroke is 5 and the average number is only 1.26. The durations of multiple return-stroke for positive and negative lightening are both positively correlated with the number of return-stroke and the overall arithmetic mean values are 250.20 ms and 343.02 ms, respectively. The negative return-stroke time interval does not vary significantly with the return-stroke order, while the positive one decreases with the return-stroke order. Overall, subsequent return-stroke intensity ratios of positive and negative lightening decrease with the subsequent return-stroke order. The first return-stroke current intensity of negative lightening increases with the number of return-stroke, while the trend of positive lightening is not obvious.

Fault Analysis and Protection Allocation Research of Park DC Microgrid

LI Wenming, SU Liang

2019, 52(5):  119-126.  DOI: 10.11930/j.issn.1004-9649.201809074

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Based on the structure and characteristics of park DC micro-grid system, the fault characteristics of different grounding modes and the requirements for fault detection devices are analyzed in this paper, and the response curve of voltage and current is deduced. Based on the topological structure of power electronic transformer, it is proved that the current has no oscillation problem under the condition of under damping. And then, the short-circuit currents before and after installing protection allocation scheme are compared, and the constraint conditions for selection of protection allocation scheme are given with consideration of such factors as equipment safety and protection coordination in case of faults. Finally, a park DC microgrid model is constructed based on the PSCAD/EMTDC platform, and a simulation is made on the proposed scheme. The simulation results indicate that:the short-circuit current decreases significantly after installing protection allocation scheme, while the current response time increases; and the parameter value obtained according to the reference condition for protection device selection satisfies the time required for fault current detection and protection judgment.

Design and Application of Real-Time Monitoring System for Local Rainstorm Water Level in Substation

WANG Jingyi

2019, 52(5):  127-133.  DOI: 10.11930/j.issn.1004-9649.201810036

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The timeliness and accuracy of early warning and the efficiency of emergency disposal have become an important part for the flood control and disaster fighting. In order to monitor the real time water level in the important production areas such as substation, and provide a support for the emergency disposal of disasters, an SCM/4G-based real-time monitoring system for local rainstorm water level in substation is put forward. A number of wireless monitoring nodes are set up in the objective area to collect the water level data, and the data is transmitted to the central server by wireless network while the real-time inquiry and alarm service is available, which can provide a theoretical basis for relevant departments in flood control and disaster fighting. The testing results show that the monitoring system is stable and reliable in water level monitoring results, and can be well applied to the early warning of disasters in important production areas.

A Method for Generating and Checking D5000 Alarm Information Based on Semantic Analysis

ZHANG Xinjie, WANG Jian

2019, 52(5):  134-141.  DOI: 10.11930/j.issn.1004-9649.201805051

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To solve the problems of vague description, undefined interval and missing alarming level existing in centralized power grid monitoring information, this paper proposes a method for generating and checking D5000 alarm information based on semantic analysis. Firstly, the automatic generation of D5000 alarm information table is realized by referring to expert knowledge base theory. Besides, the basic logic variables are automatically extracted from the alarming information table by character decomposition. Based on a comparative analysis of D5000 and ON2000 information tables, the checking and error-correcting function is also accomplished. A case study of a 110 kV substation shows that the method is valuable in simplifying the manual checking process, improving the information processing efficiency, and optimizing the management level of monitoring information.

Building and Application of Substation Digital Construction Management Platform based on BIM

ZHOU Shengdong, XIE Lei, SONG Ruochen, CHEN Hao

2019, 52(5):  142-147.  DOI: 10.11930/j.issn.1004-9649.201809041

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Through combination of the Internet, big data, Internet of things and the construction process, a deep and real digital information model of the substation is built. Based on the staged construction management process, the digital model can be implemented to display the construction growth according to the Gantt chart schedule. The QR code scan mechanism of the model is established to associate the digital model and the real construction nodes. At the same time, through building appropriate management platform and developing APP function module, the life cycle management of power transmission and transformation projects is achieved. The BIM technology is used to precisely calculate the project quantity, which strengthens the information control of material costs to improve the cost calculation efficiency and save costs.

Electricity Price Cross Subsidy Calculation Model Considering Load Characteristics of Electricity Consumers

LI Na, ZHANG Wenyue, CHEN Guoping, MA Zhao, GUO Sen, ZHAO Huiru

2019, 52(5):  148-154.  DOI: 10.11930/j.issn.1004-9649.201802018

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Suitable pricing of the electricity price cross subsidy of electricity price is not only a key point for transmission and distribution prices reform, but also important for promoting the development of electricity market reform in China. Considering the transmission and distribution prices reform as well as load characteristics of the electricity consumers, this paper proposes a electricity price cross subsidy calculation model for different kinds of electricity consumers under different voltage classes, and then empirical analysis is performed by taking a north province of China as an example. The results show:(1) residential consumers and agricultural consumers are cross subsidy receivers, of which the residential consumers obtain the most cross subsidy, namely, 92.84% of the whole package; (2) large industrial consumers and general commercial consumers are cross subsidy suppliers, of which the large industrial consumers provide the most cross subsidy, namely, 51.59%; (3) the lower the voltage level, the more the electricity price cross subsidy of residential consumers and agricultural consumers can obtain.

Assessment on Line-breakage Risk in Transmission Network based on Dynamic Probability Power Flow

CHEN Ying, GUO Xiaomin, HUANG Yu, WANG Yao, YANG Jianwei

2019, 52(5):  155-163.  DOI: 10.11930/j.issn.1004-9649.201809112

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The random variation of load and wind power output is not considered in the conventional power flow-based line-breakage risk assessment methods. The dynamic probability power flow is thus applied in the assessment of line-breakage risk in transmission network. Firstly, the dynamic probability model of load and wind power output is established. Secondly, the overload probability and the node voltage violation probability of non-fault branch lines are calculated using the dynamic probability power flow when line-breakage occurs in the power network. And then, the sequence severity indices are obtained based on power betweenness of lines and nodes. Finally, by combining the probability of line-breakage with the sequence severity indices, the dynamic probability power flow -based assessment method is proposed on the line-breakage risk in transmission network. Simulation results show that the proposed line-breakage risk assessment method is scientific and rationale, and can provide an important theoretical basis for operation planning of transmission network.

Energy-Saving Optimization on the Dust Collection System of a 330 MW Power Plant

LIU Xipu, LI Qiyong, LI Dongyang, GUO Ming, LI Jianguang

2019, 52(5):  164-169,175.  DOI: 10.11930/j.issn.1004-9649.201807029

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After the ultra-low emission transformation, it is of great significance to optimize the electricity consumption of dust collection system in coal-fired power plants with the dust emission control still maintained at the certain level simultaneously. Performance testing is an indispensable part of this energy-saving optimization. In this paper, experimental researches on the energy-saving optimization of the dust collection system under 10 operation conditions with different combinations of charging ratio, spark rate, average secondary current and average secondary voltage have been done in a 330 MW coal-fired power plant. It is discovered from the testing results regarding several basic principles of dust collection system optimization that raising parameters of the first field will lead to significantly higher dust collection efficiency, while increasing the parameter values of the last field properly will significantly lower down the final emission concentration.

Testing and Numerical Simulation on the Abrasion of SCR Catalysts

YAN Junfu, ZHAO Xuebin

2019, 52(5):  170-175.  DOI: 10.11930/j.issn.1004-9649.201808099

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Since the high-ash-content type SCR denitration system is operated under very rough conditions, the factors such as flue gas flow rate and fly ash particles even the particle diameter will contribute to the wearing away of the catalyst. Through the application of mature CFD numerical simulation software, the abrasion of SCR denitration catalyst was studied under different operating conditions regarding the impacts of flue gas velocity, ash particle diameter, fly ash mass concentration and angle of incidence, then verified through the cold test bench established by ourselves. The results show that the abrasion of the denitration catalyst is closely related to the above four influencing factors, of which the fly ash mass concentration and the angle of incidence of the flue gas make significant impacts on the wear of the catalyst. Therefore, in the actual operation, the deflector baffles should be added to alleviate the abrasions from the non-uniformity of the incident angle or the unevenness of the fly ash mass concentrations. In addition a reasonable flue gas flow rate should be set to reduce wear and tear to ensure the secure operation of the system.

Study on the Macro Non-uniform Catalytic De-NO_x Reaction Model for SCR System

SONG Yubao, ZHAO Peng, YAO Yan, XIE Xinhua, WEI Zhenzu, ZHANG Fajie

2019, 52(5):  176-184.  DOI: 10.11930/j.issn.1004-9649.201810005

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Based on the characteristics of the catalyst performance, the inherent relationship between the element potential, superposed potential and serial potential, was studied and the macro model of non-uniform catalytic De-NO_x reaction was presented and verified by measurement data. The study results indicated significant impacts of NH₃/NO mole ratio and part catalyst deactivation on the SCR performance, which would be reduced by about 8%-10% due to flue gas distribution deviation corresponding to the ultra-low NO_x emission design. In addition, the NH₃/NO mole ratio at catalyst inlet was determined by the distribution of the upstream velocity, NO_x concentration and ammonia flow at the ammonia injection grid cross-section. The large-scale mixer and the periodical tuning for ammonia injection would be helpful to improve the uniformity of De-NO_x reaction and reduce the partial ammonia slip peak value in the aspects of both design and operations.