Electric Power

Key Issues on Rural Energy Development in China

FENG Kaihui, LI Qionghui, HUANG Bibin, YAN Hu, ZHANG Hongxian

2022, 55(6): 1-8. DOI: 10.11930/j.issn.1004-9649.202202016

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In recent years, China's rural energy supply security capacity has been continuously enhanced, and the energy structure adjustment has achieved remarkable results, but some problems still exist. The low utilization rate of rural waste energy has restricted the comprehensive utilization of resources and the environmental protection; the low level of rural energy consumption and electrification has restricted the rapid integration of urban and rural development and the upgrading of energy consumption in rural areas; and the delayed construction of rural energy socialization service system has restricted the effective supply of rural energy and social equity of efficient service. In view of the problems and challenges of rural energy development in China, an analysis is made on the current situation of rural energy development in China with focus on rural domestic energy consumption. According to the particularity of China's national conditions and the specific characteristics of different regions, the key issues, such as rural waste energy utilization, rural energy electricity gasification and rural energy service system construction, etc., are studied, and some suggestions are proposed for advancing the scientific development of rural energy in China.

An Annual Peak Regulation Auxiliary Service Demand Assessment Model Based on Multi-time Scale Stochastic Optimization

LIU Huorang, YAN Wei, LIN Zugui, TAN Hong, LI Guoqiang, WEN Xu

2022, 55(6): 9-17,24. DOI: 10.11930/j.issn.1004-9649.202201044

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In order to assess the annual peak regulation demand of power system, an annual peak regulation auxiliary service demand assessment model based on multi-time scale stochastic optimization is constructed, which covers three stages: the mid-and-long term stage, short term stage and peak regulation service stage. For the mid-and-long term stage, the randomness and the balance relationship of daily electricity, maximum and minimum load are considered to optimize the mid-and-long term plan for unit maintenance, cross-day start-stop and reservoir water level. For the short-term stage, the hourly power balance of source-load and its fluctuation is considered to optimize the units output on a ten-day basis according to the mid-and-long term plan. For the peak regulation stage, the start-up conditions of the auxiliary services are simulated through analyzing the daily peak regulation capacity and water curtailment, and the deep peak regulation and start-stop peak regulation capacity of thermal power units is considered to correct and optimize the short-term plan. Based on the actual data of a provincial power grid in China, a simulation analysis is conducted, which shows that the model can effectively simulate the randomness of source-load under multi-time scale, and realize the annual peak regulation demand assessment.

Research and Application of Algorithm for Distribution Network Synchronous Phasor Measurement Unit Based on Hanning Window

YU Gaowang, FANG Chen, FAN Zhanfeng, LIN Li, GONG Yun, ZHU Yunfeng

2022, 55(6): 18-24. DOI: 10.11930/j.issn.1004-9649.202007191

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The measurement environment of distribution network is complex and poor, and the traditional synchronous phasor algorithm of transmission network is difficult to meet the requirements. The harmonic suppression ability of Fourier algorithm under common window functions is analyzed. The synchronous phasor measurement algorithm with fixed interval sampling is deduced by using three equal interval discrete Fourier transforms with Hanning window, which theoretically eliminates the influence of frequency leakage under non rated frequency, and can meet the requirements of high-precision phase measurement with good harmonic/interharmonic suppression ability. Aiming at the problem that spectrum leakage affects the calculation accuracy when multiple signals exist at the same time, the advantages of FFT interpolation algorithm with Hanning window over other window functions are analyzed and compared. Theoretical analysis and practical tests show that the measurement accuracy of phasor, harmonic / interharmonic and other quantities is improved after adopting the above scheme.

Power Load Classification Based on Feature Weighted Fuzzy Clustering

MA Zongbiao, XU Su'an, ZHU Shaobin, WANG Jing

2022, 55(6): 25-32. DOI: 10.11930/j.issn.1004-9649.202006320

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The load classification of power users provides basic guidance for the research of power system planning, load forecasting, and time-of-use electricity price. In this paper, the variational modal decomposition(VMD) and fuzzy C-means clustering algorithm(FCM) are used for power load classification. Based on the unique feature weight of Euclidean distance in FCM, a feature weighting based VMD-FCM clustering algorithm is proposed using the feature weighting based fuzzy clustering method. According to the measured load data of the power grid, the VMD method can effectively decompose the inherent modality of the data, and the introduced FCM-based weight coefficient significantly improves the algorithm's convergence speed and clustering accuracy. The clustering results show that the proposed VMD-FCM clustering method can effectively distinguish different load types and has practical application values, thereby providing guidance for the design and planning of the power system.

Fast Multi-stage Reconfiguration Method for Distribution System Based on Greedy Algorithm

ZHAO Shengju, YAO Li, LIN Jikeng, ZHANG Xu

2022, 55(6): 33-41. DOI: 10.11930/j.issn.1004-9649.202007222

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Aiming at the slow-speed computation problem of the multi-stage dynamic reconfiguration, a new dynamic reconfiguration method is proposed. Based on the given optimization scale parameter M, the proposed method makes all possible merges for 2M+2 phases which are centered on the two successive phases with the highest number of switching actions, and carries out static reconfiguration for each new merged phase, and then selects the merging scheme with a minimum objective function value as the current optimal merging scheme; repeat the iteration until the objective function value is no longer reduced and the current solution is a feasible solution, thereby obtaining the approximate optimal solution. On the premise of obtaining an approximate solution to the global optimal solution, the calculation speed is nearly 2 orders of magnitude faster than the global optimal solution. Case study shows that the proposed method has good engineering application prospect because of its high efficiency in solution.

Coupling Analysis of Energy Flow and Economic Flow in Power Grid

YU Jilai, GUO Yufeng, SHENG Yuhe, ZHANG Wei, WANG Songyan

2022, 55(6): 42-52. DOI: 10.11930/j.issn.1004-9649.202007174

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A natural coupling relationship exists between the energy flow information from power network source-flow pairs and the transaction information from power market subjects. If this relationship cannot be handled correctly, it will lead the relevant economic flow distribution information to be inaccurate, which would further affect the efficiency of power system operation and the fairness of power market operation. Therefore, based on the real-time energy flow information provided by the energy tracking method, and considering the above coupling characteristics, the economic flow distribution information along the energy delivery path chains among network source-flow pairs is discussed, and the real-time electricity price expressions serving for various cost accounting are given. For two billing ways respectively based on the sending and receiving energies in a path chain, a general principle of cost-accounting consistency is put forward. If the influence of real-time operation state of network is not considered, and the off-grid electricity price is calculated as the sum of the on-grid price, the over-grid price and the governmental fund price, the cost-accounting consistency principle will not be fully satisfied. Finally, for typical transaction modes and their associated multiple network source-flow pairs, the expressions of various economic flow distribution are proposed for quantitative analysis. Case study shows that the economic flow obtained by analyzing the real-time electricity price via considering the coupling characteristics can meet the principle of cost-accounting consistency, which will provide a theoretic basis for revealing the internal causes of cross subsidy.

Community Energy Sharing Market Model Considering Flexible Resources on Demand Side

AI Xin, XU Limin

2022, 55(6): 53-64. DOI: 10.11930/j.issn.1004-9649.202107019

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A two-sided bidding mechanism considering flexible resources on the demand side is proposed for the community energy sharing market, and prosumers and consumers of distributed solar energy are included in the market. It is assumed that the agents formed by all consumers and prosumers have flexible aggregated electric vehicles (EVs) and energy storage equipment that can be used in demand response. Firstly, a robust virtual battery (VB) model is used to describe the flexibility of aggregated EVs under price incentives to achieve reliable and economic expansion of energy storage capacity. Then, agents set the optimal charging and discharging plan for the energy storage system in the community energy sharing market to reduce the cost of electricity. After that, the managed prosumers and consumers are applied in the market, and the non-cooperative game is employed by all community consumers and prosumers to calculate the spot price in the two-sided bidding market. An iterative algorithm is presented to clear the market and minimize the uncertainty of power supply and demand. Finally, ten agents in the community are taken as examples to verify the effectiveness of the VB model for describing the flexible resources on the demand side and the community energy sharing market model.

Optimal Configuration of Multi-microgrid System with Multi-agent Joint Investment Based on Stackelberg Game

PAN Ruiyuan, TANG Zhong, SHI Chenhao, WEI Minjie, LI An, DAI Weiyang

2022, 55(6): 65-73,127. DOI: 10.11930/j.issn.1004-9649.202107162

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With more and more microgrids operate in coordination, the process of power interaction between microgrids and between microgrids and distribution networks has become increasingly complicated, which also affects the investment interests of microgrid and distribution network operators. To explore the best planning strategy for joint investment between the two, this paper proposes a method for optimal configuration of the multi-microgrid system with multi-agent investment based on the Stackelberg game. Firstly, on the basis of the multi-microgrid system model, a function model is constructed, which considering the operating costs and economic benefits of microgrid operators, investment costs of distribution network operators in microgrids, as well as interests of delays in grid upgrades and electricity sales and purchases. Then, a Stackelberg game model is built to minimize the payoff function of the multi-microgrid system and maximize the revenue of distribution networks separately. In addition, an algorithm combining the adaptive genetic algorithm and particle swarm optimization is proposed to solve the optimal configuration of distributed power in the multi-microgrid system. Finally, a comparative experiment with four sets of plans proves that the proposed planning method can better balance the revenue between multi-microgrid operators and distribution network operators.

Two-Layer Stackelberg Game Model for Energy Supply and Demand in the Park

LU Peng, FENG Chunxian, WU Weiming, WANG Tieqiang, XIE Lijuan, MA Rui

2022, 55(6): 74-79. DOI: 10.11930/j.issn.1004-9649.202011095

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Aiming at the optimization of the price and quantity of energy dealers and users in energy trading in the park, this paper proposef a two-layer Stackelberg game model of the price and quantity of energy supply and demand in the park.The upper-level model energy business aimed to maximize its own interests, considered the multi-energy flow rate balance constraints and external grid interaction constraints, power-to-gas, power/heat, gas turbines and other source-storage constraints, at the same time determined energy prices through competition. The lower model considered the user's energy demand response, aimed to minimize the energy cost, considered the load demand constraint, and determines the energy demand according to the decision price of the energy supplier. The energy supplier further optimized the energy price according to the user's energy demand, and iterated until convergence. The results of the example show that it can effectively maximize the benefits of both parties.

Energy Storage Market Trading Mechanism and Benefit Analysis of Zhejiang Power Spot Market

ZHUANG Xiaodan, LIU Weidong, HUANG Weiqun, DENG Hui, WANG Wei

2022, 55(6): 80-85. DOI: 10.11930/j.issn.1004-9649.202105023

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The rapid development of energy storage promotes the consumption of clean energy and ensures the safe and stable operation of power grid, but it also brings new challenges to the mechanism design of energy storage to participate in the power market. Based on the experience and enlightenment of energy storage participating in the spot market in the domestic and overseas, taking Zhejiang Province as an example, the benefits of energy storage participating in spot energy market and frequency regulation auxiliary service are simulated and calculated respectively. The results show that due to the influence of energy storage conversion efficiency, power loss and the cost of transmission and distribution system, the overall income of energy storage participating in the electric energy market does not achieve the expectation, but it has certain advantages in the frequency regulation auxiliary service.

Key Transmission Section Search Strategy Based on Improved Clustering Algorithm

WANG Jie, DING Ming, SUN Lei, WANG Liubing

2022, 55(6): 86-94. DOI: 10.11930/j.issn.1004-9649.202012131

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In order to effectively avoid the occurrence of cascading failure due to the loss of faulted or overloaded lines, a key transmission section search method based on an improved fuzzy C-means clustering algorithm is proposed. Firstly, an improved particle swarm optimization algorithm is employed to update the clustering center, so that the problem that the clustering algorithm is sensitive to the initial clustering center can be solved. Then the initial transmission section is obtained based on the improved clustering algorithm. The Floyd algorithm is used to search the shortest circuit and sub-shortest circuit with the disconnected lines, and the missing lines are added to the initial transmission sections to form the candidate transmission sections. Finally, the composite factor criterion is proposed to determine the key transmission sections. Case studies are made on the IEEE 14-bus and IEEE 118-bus standard systems, and it is proved that the proposed method can accurately search out the lines in the system that are significantly affected by the cut-off lines and may have the risk of cascading tripping, i.e. the key transmission sections. The results show that the key transmission sections obtained by this method are more practical and valuable in engineering.

Corona Loss Prediction of UHV AC Transmission Line Based on DBN Neural Network Optimized by PSO

HUANG Shumin, JIANG Lingao, LI Zhichuan, YANG Guangxu, SONG Fugen

2022, 55(6): 95-102,214. DOI: 10.11930/j.issn.1004-9649.202112041

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Based on the correlation between corona loss of UHV AC transmission lines and weather conditions such as rainfall, specific humidity, temperature, relative humidity, pressure, etc., a corona loss prediction method for UHV AC transmission lines is proposed by predicting corona loss of UHV AC transmission lines under some weather conditions. Based on the optimization mechanism of particle swarm optimization (PSO) and the prediction principle of deep belief network (DBN), the intelligent algorithm mechanism of this prediction method is explained in detail, and a complete set of prediction methods based on PSO—DBN intelligent algorithm is proposed. Firstly, the weather conditions that have strong correlation with corona loss are determined by the size of the Spearman correlation coefficient and used as the characteristic values. Then the DBN neural network is built with the selected eigenvalues as the index system to predict the corona loss. Then the internal parameters of the DBN neural network are adjusted by PSO optimization algorithm to improve the prediction accuracy of the DBN neural network. Finally, the proposed algorithm is used to predict the corona loss of the actual Fujian—Zhejiang UHV transmission line, and the statistical corona loss values of the line are compared and analyzed to verify the feasibility of the proposed prediction method. This method provides reference for corona loss research and engineering design of extra high voltage transmission lines.

Simulation Experiment on Discharge of Plastic Film Overlapping on UHVDC Transmission Lines

WANG Shenghui, WANG Ximing, DONG Xinghao, ZHOU Jun

2022, 55(6): 103-110. DOI: 10.11930/j.issn.1004-9649.202202038

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In order to study the discharge phenomena of plastic film overlapping on UHV DC transmission lines and explore the cause of flashover fault of a ±800 kV UHV line, an experimental study is conducted on the flashover characteristics of plastic film with three different gap distances of 1.0 m, 2.0 m and 11.5 m, and the relationship between flashover voltage and plastic states, including dry and wet state, spreading and rolling state, is studied through analyzing the equivalent salt density of three typical areas on the surface of plastic film. The results show that, when the gap distance is 1.0 m and 2.0 m, the gap flashover potential gradients of wet plastic film are 1.22 kV/cm, 0.96 kV/cm, 0.82 kV/cm and 0.7 kV/cm respectively for the spreading out and rolling up state; When the gap distance is 11.5 m, the gap flashover potential gradient of the wet plastic film is 0.56 kV/cm. Under the condition of moisture, the plastic film in rolling up state is more prone to flashover than that in spreading out state, and the average flashover potential gradient decreases with the increase of gap distance. Finally, the causes for the failed three times of restart of a ±800 kV UHV line caused by short circuit of plastic film is analyzed.

Construction and Application of Discrete-Time-Domain Framework -based Power-Grid State Space

XIONG Wei, ZHANG Yue, DOU Jianzhong, JIANG Baofeng, SHAN Lianfei

2022, 55(6): 111-117. DOI: 10.11930/j.issn.1004-9649.202111085

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To obtain the eigenvalue more efficiently and conveniently, a discrete time domain model (DTDM) based state space construction method is proposed for power grids, and the stability criterion of is presented. Compared with the traditional methods, the nonlinear components can be linearized naturally in the proposed method so as the construction of the power-grid state space is simple. Meanwhile, the DTDM based state space can capture a wider range of system information at one time and is not restricted by the model of electrical equipment. That is the whole state space of power grids can be obtained only by the DTDM of the components and the topology of the power grid. The calculation of the eigenvalue is simple and efficient, and it can give the trend of the eigenvalue and predict the stability of the power system.

A Feasible Topology of DC Collection Valve for Long-Distance Offshore Wind Farms and Cost-Effective Analysis

LIAO Xiupu, ZHOU Quan, LI Lei, LI Binbin, WANG Zhiyuan, YANG Ming, XU Dianguo

2022, 55(6): 118-127. DOI: 10.11930/j.issn.1004-9649.202108068

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HVDC is a preferred technology for high-power and long-distance offshore wind farms, and the valve plays a pivotal role. Due to the high cost, large footprint and weight of valve, and high construction cost of offshore platform, an evolution is anticipated from traditional modular multilevel converter (MMC) based AC collection valve to the DC/DC transformer (DCT) based DC collection valve. Firstly, based on analyzing the technical characteristics and feasible topology of the DC collection valve, it is proposed to adopt the capacitive energy transmission (CET) principle based DCT, which presents low-cost, small footprint, light weight and low power loss. And then the topology of CET-DCT is improved into the bipolar topology for engineering applications, and the operation principle is also discussed. The effectiveness of the DC collection valve has been verified by simulation and experimental results, and the cost-effectiveness of the CET-DCT based DC valve is concluded by comparison with the MMC based AC collection valve.

Influence of 500 kV AC Lines on Safety Protection of Live Working Personnel in Parallel ±800 kV DC Lines

MA Aiqing, WANG Jie, BI Yongxiang

2022, 55(6): 128-136. DOI: 10.11930/j.issn.1004-9649.202007015

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In order to ensure the reliable operation of AC 500 kV and DC ±800 kV parallel transmission lines without power failure, the three-dimensional finite element model and electromagnetic transient model are used to study the safety protection of EHVAC and UHVDC transmission lines live working in hybrid lines. The safety protection is analyzed through the three aspects of body surface electric field, transfer current and transient energy. The results show that the worker's body surface electric field changes with the change of the phase of the AC line. The distance between the worker and the UHVDC transmission line is closer, the effect of the AC transmission line on the surface electric field is more obvious. Compared with the independent UHVDC transmission line, the worker's body surface electric field and transfer current amplitude in the mixed line have increased significantly, the transient energy value relatively has a small increase. In the hybrid line, it is recommended that the worker’s potential transfer work should be proceeded at a distance between 0.4 m to 0.5 m from the conductor with suitable screen clothes.

An Overhead Conductor Temperature Calculation Method Based on Elevation Wind Speed Prediction

CHEN Zhengganzhe, ZHANG Bin, FAN Yazhou, WU Yunfa

2022, 55(6): 137-145. DOI: 10.11930/j.issn.1004-9649.202011014

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The wind speed used in overhead conductor temperature calculation is usually measured near to ground. The low precision of the measurement leads a large deviation in temperature calculation, resulting high difficulty in line operation and maintenance. To overcome this problem, a temperature calculation method of overhead conductors based on elevation wind speed prediction is proposed in this paper. Taylor formula iteration method is used in the calculation process to realize the fast and accurate calculation of wire temperature. Integrating the finite element method with the basic heat transfer principles, the temperature of overhead conductors is simulated in ANSYS, and the simulation results prove the reasonableness of the proposed method. Finally, the practical application results verify its effectiveness.

Analysis and Simulation of Measured Wind Speed and Wind Speed Correction Method of Tower Under Microtopography

FANG Chunhua, TAO Yuning, ZHANG Wei, ZHI Li, LI Jing

2022, 55(6): 146-153. DOI: 10.11930/j.issn.1004-9649.202011004

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The operation safety of transmission lines is greatly affected by strong wind, but the previous research lacks the measured wind speed data and ignores the influence of micro topography on wind speed coefficient. Based on the measured data of meteorological stations, this paper studies the distribution characteristics and recurrence period of wind speed, completes the correction and Simulation of fluctuating wind speed spectrum, obtains the micro terrain parameters of transmission lines through Google Earth, proposes four kinds of wind speed correction methods under micro terrain, and calculates the wind speed correction coefficient. The results show that GeV model is more suitable for fitting probability distribution density of wind speed in Jiangsu Province. The design wind speed of UHV transmission tower in Jiangsu area should be between 34.5 m/s and 39 m/s. According to the time history data of wind speed in the period of monsoon typhoon monsoon, the fluctuating wind speed spectrum is highly consistent. When the tower nominal height is 1, the wind pressure correction coefficient increases with the increase of peak height or slope angle; when the tower nominal height / mountain height is higher than 3.0, the wind pressure correction coefficient is fixed. The research results can accurately calculate the wind speed of the tower in the micro terrain area near the meteorological observation station based on Google Earth micro terrain data.

Load Reduction Potential of Tea Production Energy System Based on Transcritical CO₂Heat Pump

ZHOU Anren, WANG Jianrong, MA Zhiquan, LI Weilin

2022, 55(6): 154-160,171. DOI: 10.11930/j.issn.1004-9649.202104079

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The fossil energy equipment in rural industry has been gradually replaced by electric energy technologies, which, however, causes increasing fluctuation of rural power load and concentrated high load in some periods. In order to solve the above-said problem, the low-grade clean energy has been applied to tea production in rural areas, and the transcritical CO₂ heat pump tea drying technology is proposed according to the technical requirements of the whole-process tea drying. Taking a tea production village for a case study, an analysis is made on the annual daily power consumption and the daily load for tea production in its representative village. The results show that the load can be reduced to 39.6%~46.8% of the original load after using CO₂ heat pump tea drying, and the ratio of peak load to normal load can decrease from 13.6 to 5.4~6.2. The application of transcritical CO₂ heat pump in production of farm produce can effectively relieve the power supply pressure in rural areas.

Comprehensive Performance Evaluation of UHV Power Transmission Project Based on Bayesian Best-Worst Method and Improved Matter-Element Extension Model

ZHAO Huiru, ZHAO Yihang, WANG Luyao, FENG Kaixin, LI Bingkang, GUO Sen

2022, 55(6): 161-171. DOI: 10.11930/j.issn.1004-9649.202012003

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Due to the inconsistency between energy consumption centers and energy production distribution patterns in China, it is of great significance to build UHV power transmission projects that are characterized with long distance, large capacity and low loss. The performance evaluation of an UHV power transmission project is the key to judging whether the project can achieve the expected goals and meet the requirements of project construction. A comprehensive performance evaluation index system is constructed for UHV power transmission projects from four dimensions of operation, finance, environment and society, and a comprehensive performance evaluation model is proposed for UHV power transmission projects based on Bayesian best-worst method and improved matter-element extension model. The former combines Bayesian theory and the best-worst model to determine the weight of each criteria, while the latter improves the traditional matter-element extension model to achieve the grade ranking of the comprehensive performance for UHV power transmission projects. A case study is made on a ±800kV UHVDC power transmission project, and the result shows that the overall performance of the project falls into ‘Medium’ grade. The case study shows that the proposed model is effective and scientific for comprehensive performance evaluation of UHV power transmission projects.

Mixed-frequency Asymmetric Measure of China's Electric Power Industry Prosperity Index

ZHOU Decai, CHEN Jinjin, LIU Bo

2022, 55(6): 172-185. DOI: 10.11930/j.issn.1004-9649.202006195

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In view of the problem that the traditional co-frequency power prosperity index lacks timeliness and dynamism, a MF-MS-SW model is constructed, which can analyze both the quarterly and monthly frequencies at the same time. Leading, consistent and lagging mixed-frequency sample data consisting of 21 economic indicators are selected to construct China's mixed-frequency power prosperity index and early warning signal system. The results show that the proposed MF-MS-SW measurement model has a good description of the fluctuation characteristics of China’s power prosperity index, i.e., multiple-frequency and nonlinear characteristics, and has a high degree of consistency with China’s overall economic development status. The model can be used for early warning and forecasting. It is recommended that the energy and power sectors regularly compile and publish China's power prosperity index, reflecting the real-time changes in the power industry's economic status and promoting the optimization and adjustment of energy structure.

Capacity Configuration and Control Strategy of Hybrid Energy Storage to Smooth Wind Power Fluctuations

XU Yanhui, XU Yijia

2022, 55(6): 186-193. DOI: 10.11930/j.issn.1004-9649.202201073

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In order to smooth the output power of wind farms and reduce the influence of wind power fluctuations on power grid, a hybrid energy storage system consisting of energy-based energy storage element electrolyzer and power-based energy storage element supercapacitor is adopted to smooth wind power fluctuations. Firstly, the energy storage output in a large number of time slots is analyzed by probability statistics, and the smoothing effect of wind power fluctuation is evaluated by the probability change of the grid-connected power fluctuation within the limit of wind power fluctuation, and the power at a given confidence level is taken as the rated power of the hybrid energy storage. On this basis, the hybrid energy storage power is decomposed by the adaptive sliding window algorithm considering the economy, and the rated capacity of the supercapacitor and the rated power of the electrolyzer are determined, so as to realize the capacity allocation which takes into account the economy and fluctuation stability effect. Secondly, based on the charging state of the supercapacitor, the rated power of the electrolytic cell and the overall power command of the energy storage system, the operation control strategy of the hybrid energy storage system is formulated. Finally, the simulations results show that this method can effectively reduce the fluctuation of wind power while realizing the power distribution and ensuring the normal operation of each energy storage module.

Multi-objective Optimization Strategy of User-Side Energy Storage Operation Differentiating Working / Nonworking Load

SUN Weiwei, KOU Xiaowen, ZHOU Guang, LI Manli

2022, 55(6): 194-201. DOI: 10.11930/j.issn.1004-9649.202108060

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Under the two-part electricity price, in order to make more efficient use of energy storage and improve the comprehensive benefits obtained by users, a user side energy storage multi-objective optimization strategy distinguishing working / nonworking load is proposed by constructing demand management, energy storage income, load fluctuation increase rate and SOC process control model. It can effectively realize the multi-objective optimization of reducing the monthly power consumption cost of users, reducing the increase rate of load fluctuation range and reducing the times of energy storage charge and discharge and standby state conversion. An example of a large industrial user is optimized by calling CPLEX solver with MATLAB to verify the feasibility of the strategy.

Annual Fuel Cost Minimization Decision Model for Thermal Power Plant and Its Applications

LIU Xiwen, PENG Zhuoyin, HU Xinqiang, YE Ze, HE Huixue, CAI Rui, WEI Wenbo

2022, 55(6): 202-207. DOI: 10.11930/j.issn.1004-9649.202012042

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Fuel cost accounts for 60%–70% of the production cost of a power plant, and the management of fuel cost has a direct influence on the power plant’s economic benefits. At present, the thermal power plants in China have attached great importance to the whole process of fuel cost management. Based on the relationship among fuel purchase cost, inventory cost and loss cost, an annual fuel cost minimization decision model is established for thermal power plants. The actual operation data of a power plant in 2019 was calculated for decision making. The results show the decision in fuel purchase timing and purchase volume reduced the total annual fuel cost, the annual fuel procurement cost, and the annual fuel inventory and loss cost by 1.18%, 1.14% and 1.43%. respectively. The proposed model provides a new method for scientific management of the fuel cost in thermal power plants.

Analysis of Energy and Material Consumption Characteristics of Double Tower Double Cycle Desulfurization System for Ultra Low Emission Unit

DU Zhen, ZHANG Cheng, ZHU Yue

2022, 55(6): 208-214. DOI: 10.11930/j.issn.1004-9649.202107057

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In order to systematically analyze the energy and material consumption characteristics of double tower double cycle desulfurization system, testing the power consumption, water consumption and limestone consumption at the exit of double tower double cycle desulfurization systems in 53 ultra-low emission units. And study the effects of inlet SO₂ concentration, liquid gas ratio, pH value and Ca/S ratio on the energy and material consumption characteristics of unit mass SO₂ removal. The measurement results indicate that the the energy consumption of SO₂ removal accounts for 55%~80% of the total removal cost, while the power consumption of circulating slurry pump accounts for 50%~70% of the total energy consumption. The energy consumption per unit of SO₂ removal in primary and secondary absorption tower decreases with the increase of inlet SO₂ concentration, and the energy consumption per unit of SO₂ removal in secondary absorption tower is much higher than that in primary absorption tower, The energy consumption per unit of SO₂ removal in the first and second stage absorption towers decreased first and then increased with the increase of pH value. Which shows that in order to reduce the energy and material consumption per unit mass of SO₂ in the double tower double cycle desulfurization system, the SO₂ concentration at the inlet of the primary absorption tower should be controlled at 4 000~6 000 mg/m³, and the slurry pH value should be controlled at about 5.2; The concentration of SO₂ at the inlet of secondary absorption tower should be controlled at 1200 mg/m³, and the pH value of slurry should be controlled at about 6.0.

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