Table of Content

25 May 2021, Volume 43 Issue 5

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Intelligent Power Energy Conservation and Environmental Protection New Energy

Intelligent Power

Multi-objective optimization of PI controller parameters under robustness constraint and its application

JING Likun, TANG Yiqiang, PAN Fengping, WU Zhenlong

2021, 43(5):  1-8.  doi:10.3969/j.issn.1674-1951.2021.05.001

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Though a proportional-integral （PI） controller is of simple structure and good operability,its parameters can barely satisfy the control on the controller. To improve its operation quality, a multi-objective optimization method for PI controller parameters under robustness constraint is proposed. Taking maximum sensitivity function as the robustness constraint index and setting the tracking performance and anti-interference as optimization objectives simultaneously, the method can get Pareto optimal solution satisfying the robustness constraint after optimizing PI controller parameters in their stable regions by multi-objective algorithm. Then, the parameters are optimized by level diagrams. PI controller parameters of No.3 high-pressure heater of a power plant in Weifang, Shandong Province were optimized by this method. The test results show that,taking the proposed method,the fluctuation of high-pressure heater water level is about 61.89% of the original one only, which indicates the promising application prospect of this method on industrial site.

Prediction method for NO_x discharged from SCR denitrification systems based on IQGA-GRNN model

CAO Xiguo, ZHANG Yongtao, LI Yatian

2021, 43(5):  9-14.  doi:10.3969/j.issn.1674-1951.2021.05.002

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According to the complex craftwork and non-linear characteristic of SCR denitrification systems, a mathematical model for NO_x discharged from coal-fired power plants was created based on Improved Quantum Genetic Algorithm （IQGA） and General Regression Neural Network （GRNN）. Firstly, QGA was modified by revolving door to get the search results more accurate. Secondly, the smoothness factor in GRNN was optimized to improve the approximation ability of the algorithm. Taking a 300 MW heat-supply unit as an example, an IQGA-GRNN model was created and trained by the training data of the unit. The maximum error between the predicted value made by the model and the measured value is within 8.0%, and the average error is within 0.2%. The IQGA-GRNN model is supportive for precise control on NH₃ spray.

Architecture and key strategy of online state assessment system for substation auxiliary power supply system

WANG Liding, ZHAN Qingcai, YIN Jianjun, YANG Changfu, WANG Junhui, NIE Xiaobo

2021, 43(5):  15-22.  doi:10.3969/j.issn.1674-1951.2021.05.003

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Auxiliary power supply system of a substation is important to the station's safe and reliable operation.The system is mainly composed of AC power supply system,DC power supply system and AC uninterruptible power supply system.To effectively evaluate the operation states of AC and DC power supply systems,an online state assessment system for substation auxiliary power supply system is proposed which works with the collaboration of the main system and the subsystem.After introducing the main functions and components of the main and sub-systems,the assessing process and the criteria for assessing the AC power supply equipment,inverter power equipment,DC/DC communication power supply equipment and DC power supply equipment are expounded.According to its application situation in a substation,the assessment system is proven to be effective in keep the safe and reliable operation of auxiliary power supply system in substation.It is of engineering application value.

Application of blockchain technology in energy digital economy

WANG Cheng, CUI Weiping, GAO Hongda, HE Peng, LIU Rui, LIU Jianye, CHEN Guang, LI Xinda

2021, 43(5):  23-29.  doi:10.3969/j.issn.1674-1951.2021.05.004

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As an important technology for energy digitization,blockchain technology is characterized by distributed computing,storage,data sharing,sharing,openness and transparency,non-tampering and traceability,which can provide technical support for this industry.The deadlock of energy digital economy can be broken by blockchain.The role of blockchain played in building a new production relationship in digital energy economy is analyzed from three aspects：ownership of the means of production,new production relations and product distribution.Meanwhile,based on the new production relationship,there are three application scenarios of blockchain in energy digital economy,namely the metering of energy data,electronic contracts and power outage insurance.By analyzing and summarizing the application scenarios above,it is expounded that the integration of business mode and other digital technologies is key to the research.In the development of blockchain,the storage space and user privacy are the key problems to be solved.

Research and application of intelligent interactive platform for power consumption information based on data integration

YE Ling, CHANG Wenliang, LONG Quan

2021, 43(5):  30-35.  doi:10.3969/j.issn.1674-1951.2021.05.005

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Taking data integration,Ant Design system,WeChat Public Platform and Serverless workflow and other technologies,an intelligent interactive platform for power consumption information based on data integration is built to deal with the lack of intelligent personalized marketing service on user end,inconvenient communication channel and asymmetric access to power consumption information.The platform architecture considers data support,application services and business applications.Focusing on basic and value-added services,the platform sets up its functional architecture to realize intelligent business flow,precise information push and close-loop process control.The application modes of the platform for customer management and service were illustrated in three scenarios which were routine safety inspection,power outage information push and energy consumption optimization.Finally,the leadership of digitalization in management and service mode improvement of power supply enterprises is summarized.

Research on service life prediction on rolling bearings based on vibration signal analysis

TAN Zhiling, CHEN Caiming, XU Shengchao, WU Zhihong, SONG Yin, WANG Pengfei

2021, 43(5):  36-44.  doi:10.3969/j.issn.1674-1951.2021.05.006

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The prediction on residual life of rolling bearings is complex because of the multiple categories and multiple features.It is difficult to apply traditional prediction methods based on mechanics and probability statistics on engineering practices.In the following study,the service life of a rolling bearing was predicted based on vibration signal analysis.Firstly,feature extraction in time and frequency domains was made on the collected vibration signals and wavelet packet sample entropy.Then,the features with high correlation to the bearing's life span were selected by Pearson correlation analysis as the sample set of bearing life prediction.The selected characteristic parameters were taken as the inputs training the improved particle swarm optimization-General Regression Neural Network（PSO-GRNN） model to construct the bearing life prediction model.Comparing the results made by this bearing life prediction model,back propagation（BP） Neural Network model and PSO-GRNN model,the proposed model is verified to be more stable and accurate.

Energy Conservation and Environmental Protection

Simulation and optimization for Urea-SCR system of the natural gas internal combustion engine in a distributed energy station

ZHAO Dazhou, WANG Mingxiang, RUAN Huifeng, GU Jing, WANG Mingxiao

2021, 43(5):  45-52.  doi:10.3969/j.issn.1674-1951.2021.05.007

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In order to improve the NO_x removal rate of a Urea-SCR system, a three-dimensional numerical model of a 9.7 MW natural gas internal combustion engine's Urea-SCR system was established. The effects of the static mixer, porous plate in the reactor on flow field, NH₃ conversion rate and NH₃ mole fraction distribution were studied. Simulation results show that, the farther the injection location is from the first-layer catalyst, the higher the NH₃ conversion rate is and the more evenly the NH₃ distributes. A baffle static mixer will hamper the uniformity of flow velocity at the inlet of the first layer catalyst,which is not conducive to the transformation and mixing of NH₃. The porous plates arrangement in the diffuser can effectively improve the uniformity of the flow field in front of the inlet of the first layer catalyst and improve the conversion of NH₃.However,it is not conducive to the mixing of NH₃. Laying porous media on the standby layer of catalyst, an ideal conversion rate and decent NH₃ uniformity can be obtained.

Water balance analysis for the flue gas water removing technology within ceramic membrane

HAN Changliang, GU Xiaobing, YUAN Zonghai, LI Gang, SUN Baomin, GAO Dan

2021, 43(5):  53-58.  doi:10.3969/j.issn.1674-1951.2021.05.008

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Water balance models for a desulfurization system and a water removal system were built to assess the capacity of ceramic membrane in water removal and wet plume eradication.The operation results of a 600 MW unit show that the exhaust gas temperature and unit load are directly proportional to the water captured by the water removal system.A boiler taking lignite as fire coal demands the least amount of process water supplement which is far exceeded by the water captured by the water removal device.To meet the requirement of wet plume eradication in winter,the captured water mounts up.The captured water increases by 25 t/h for every 10% increase in dewatering efficiency of the ceramic membrane,but the exhaust gas temperature at the chimney outlet will be lower.When the efficiency rises from 10% to 60%,the exhaust gas temperature falls by 14.28 ℃,and the plume rise height reduces by 176.5 m.In the proper condition,the plume removal technology of the water removal system can effectively reduce the water consumption made by the desulfurization system,which is of great significance to the overall water saving.

Study on theoretical calculation of desulfurization slurry injection pressurization device

ZHANG Xiqian, YANG Pengfei, WU Chong

2021, 43(5):  59-63.  doi:10.3969/j.issn.1674-1951.2021.05.009

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A coal-fired power plant can effectively eliminate gypsum rain by reducing the flue gas temperature and moisture content at the outlet of wet desulfurization system,realize desulfurization water saving and reduce the emission of condensable particulate matters such as ultrafine particles and aerosols.Some coal-fired power plants reduce the flue gas temperature and moisture content by installing cooling devices on desulfurization circulating slurry pipelines,resulting in increased resistance in the pipelines,insufficient outputs of the slurry circulating pumps and decreased desulfurization efficiencies.To solve these problems,by carrying out a theoretical analysis from the aspect of fluid mechanics,a theoretical design for a slurry injection and pressurization device was obtained.Taking a desulfurization project as an example,the design was proven to be feasible and provides theoretical guidance for the design of other slurry injection and pressurization devices.

Experimental study on deep peak-load shaving of a 660 MW ultra-supercritical secondary reheating unit

CONG Xingliang, XIE Hong, SU Yang, ZHANG Jun, CHENG Yingjie

2021, 43(5):  64-69.  doi:10.3969/j.issn.1674-1951.2021.05.010

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To adapt to the development trend of coal-fired units in the context of realizing carbon peak and carbon neutrality, deep peak-load shaving study was made on a 660MW ultra-supercritical secondary reheating unit. The experiment verified that the unit performs well at 30% rated load. Under 30% rated load, the combustion in the boiler is stable and in good condition. The control and operation parameters of the main and auxiliary equipment are normal and stable with adjustment margins. The environmental protection equipment works well and keeps the discharged pollutant within the ultra-low emission standards of China. However, the economic performance of the unit running with 30% rated load is inferior to that with 50% rated load. Influenced by heat consumption for steam turbine unit,heat consumption for boiler and auxiliary power rate,coal consumption for power supply of the unit running with 30% rated load is much higher than that of the unit with 50% rated load,increasing by 49.0 g/（kW·h）.Thus,the parameters of units under deep peak-load shaving need to be further adjusted and optimized.

New Energy

Optimal center height of the receiver in a 100 MW solar power tower plant

GAO Song, REN Bohan, XU Jigang, XU Zhiqiang, LI Hongfei

2021, 43(5):  70-74.  doi:10.3969/j.issn.1674-1951.2021.05.011

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In order to reduce the power generation cost of solar power tower plants, center heights of the receivers should be optimized for stations' efficiency improvement. The optimization method for the receiver's central height in a 100 MW solar power tower plant was investigated. The influences of the receiver's height on the quantity of heliostats and the power plant output were simulated after model construction. The height of the receiver was obtained by the minimum power generation cost method. The results show that, with the increase of the receiver's height, power generation cost will touch bottom. With a certain heat storage capacity, the power generation cost can bottom out with a receiver tower height at 220 m. By the means of optimizing receiver towers height, the investment cost can be reduced and the economy can be improved.

Wind speed correction for wind turbine based on convolutional neural network

YANG Mingming

2021, 43(5):  75-79.  doi:10.3969/j.issn.1674-1951.2021.05.012

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The wind turbine nacelle anemometer is affected by the wake of turbines and disturbance of blade.International Electrotechnical Commission（IEC） indicated that nacelle transfer function cannot accurately describe the complex relationship between measured wind velocity and inflowing wind velocity.A nacelle wind speed correction model based on convolution neural network is proposed.The model adopting multi-layer convolution pooling can effectively filter the influence brought by turbine wake and blade disturbance,abstract feature variables,and improve the accuracy of the corrected wind speed.The engineering example shows that the fitting accuracy R² of the convolution neural network method is 0.844 7,and its mean absolute error （MAE） is only 0.071.The difference between the power calculated by this method and the one measured by anemometers is only 4.07%.All the deviation indexes are better than those made by IEC nacelle transfer function,which fully reflects the advantages of the wind speed correction model.

Discussion on sustainable development of large hydropower projects in southwestern China under new situation

XU Ganglei

2021, 43(5):  80-85.  doi:10.3969/j.issn.1674-1951.2021.05.013

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By the end of 2019,the installed capacity of hydropower units in China has reached 3.564 TW,and the annual power generation is around 1.3 PW·h.Hydropower has become the central pillar of energy structure adjustment.The proposal of carbon neutrality and carbon peak makes it more urgent to solve the problem of renewable energy consumption.The 13th Five-Year Plan for hydropower development makes it clear that the subsequent development of hydropower should concentrate in southwestern regions.Under the new situation,although the abandoned hydropower has been lowered,the continuous decline of electricity price and increasing exploration cost of hydropower seriously restrict the sustainable development of large hydropower projects. In response to this,a reasonable mechanism for sustainable development is discussed combining the current development strategy and macro regulation strategy.It is suggested that,upholding the principle of "allowable cost plus reasonable income",a sustainable hydropower electricity price mechanism "benchmark price + floating price" is cosntructed,which can promote the high-quality development of hydropower energy.