Table of Content

28 January 2022, Volume 55 Issue 1

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Review on Large-Scale Centralized Energy Storage Planning under Centralized Grid Integration of Renewable Energy

GU Chenjia, WANG Jianxue, LI Qingtao, ZHANG Yao

2022, 55(1):  2-12,83.  DOI: 10.11930/j.issn.1004-9649.202105017

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With the large-scale centralized grid integration of renewable energy, the problem of renewable energy consumption is becoming more and more prominent. As an important part and key supporting technology of the high-proportion renewable energy power system, the large-scale application of energy storage is conducive to improving the flexibility, economy, and security of the system. However, most of the current reviews focus on the summary of energy storage technologies, and few make a comprehensive review of energy storage planning methods, especially the configuration methods for large-scale energy storage on the source-grid side. Therefore, this paper analyzed the overall impact of including large-scale energy storage into power system planning, summarized the application scenes of energy storage in the power system, and then analyzed the impact of the introduction of energy storage on the modeling of planning problems. Next, the source-grid-side planning of large-scale energy storage and the planning of source-grid coordination considering large-scale energy storage were expounded. Finally, the key issues of the current large-scale energy storage planning and its prospects were discussed.

Review of Energy Storage Configuration Technology on Renewable Energy Side

LI Xiangjun, MA Huimeng, JIANG Qian

2022, 55(1):  13-25.  DOI: 10.11930/j.issn.1004-9649.202109032

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Building a new power system with renewable energy as the main body is an important responsibility and mission of the energy and power industry to serve carbon peak and carbon neutrality. The requirements of the power grid for renewable energy have been gradually upgraded from “friendly grid connection” to “friendly grid connection + active support”. It has become a general trend to install energy storage systems on the renewable energy side. Energy storage configuration is the front-end work in the field of energy storage application, but the cost of energy storage is still high. Therefore, the primary task is to find ways to achieve the optimal energy storage configuration. This paper reviews and summarizes the research progress of application scenarios, configuration methods, and pre-assessment methods of energy storage in the field of renewable energy both at home and abroad. Moreover, issues that need to be further considered in the energy storage configuration on the renewable energy side are proposed, and future research directions are predicted.

Analysis and Calculation of Energy Storage Configuration in Power System

DONG Yu, FAN Gaofeng, DONG Cun, YU Ruoying, ZHAO Junyi

2022, 55(1):  26-36.  DOI: 10.11930/j.issn.1004-9649.202101138

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At present, the configuration analysis and calculation of energy storage are mostly carried out around a single scene, which cannot give full play to the multiple functions of energy storage. Therefore, this research was conducted to achieve an orderly energy storage configuration and promote the comprehensive benefits of the power system. Starting from the overall operation demand of the power system, this paper summarized three key factors that should be considered for the energy storage configuration: the source-grid-load development, the replacement effect of energy storage on conventional units, and the comprehensive optimization of energy storage charging/discharging strategies. Then, an innovative analysis and calculation method for the overall configuration of energy storage in the power system was proposed in the case of uncertain power, energy, and charging/discharging time. The method included the initial value calculation of energy storage power, energy analysis and calculation under determined power, and energy rolling calculation under different power. Finally, a provincial power system was taken as a case to analyze and calculate the energy storage configuration from 2021 to 2025. The calculation results showed that the energy demand of the system could be reduced to a certain extent if the configuration had multiple feasible solutions and the energy storage power increased within a certain range. For economic consideration, the one with the least investment cost was chosen from all the feasible solutions as the final configuration scheme.

Optimized Energy Storage Configuration of Wind Power Integrated Power System Considering DC Regulation Capacity

PENG Sui, GONG Xianfu, LIU Xinmiao, LU Xun, WU Yunyun, XUE Xizhen, ZHOU Bo, AI Xiaomeng

2022, 55(1):  37-45.  DOI: 10.11930/j.issn.1004-9649.202107048

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With the increasing installed capacity of wind power, stronger demand for flexible adjustment resources such as energy storage occurs in the power system, and the AC/DC hybrid power grid is the basis for the grid connection, transmission, and accommodation of large-scale wind power. Given the above background, an energy storage configuration scheme is proposed for the wind power integrated system considering the DC regulation capacity to promote the accommodation of renewable energy and reduce the investment cost of energy storage. First, a scenario analysis method is adopted to deal with the randomness of wind power and loads. Then, a DC line model with adjustable transmission power is constructed. Furthermore, combined with the constraints including energy storage configuration, energy storage operation, and AC power grid, a configuration model of energy storage based on multi-scenario stochastic optimization is built considering DC regulation capacity to minimize the total daily operating cost of the power system. Finally, a comparative analysis of multiple energy storage configuration schemes is simulated in the modified IEEE 14-bus system. The results show that the proposed scheme can promote the accommodation of wind power while lessening the demand for energy storage. As a result, the economic operation of the wind power integrated system is guaranteed.

Capacity Proportion Optimization of Wind, Solar Power and Battery Energy Storage System for Regional Power Grid Based on Source-Load Matching

LI Pai, FANG Baomin, QI Taiyuan, HUANG Yuehui, SHI Zhaodi, WANG Lianfang

2022, 55(1):  46-54.  DOI: 10.11930/j.issn.1004-9649.202012091

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Capacity proportion optimization of the wind, solar power, and battery energy storage system is the basis for efficient utilization of renewable energy in a large-scale regional power grid. In this regard, an optimization method based on source-load matching was proposed to allocate the capacity proportion of the wind, solar, and battery energy storage system in a regional power grid. An optimization model was built to maximize wind and solar power generation. The optimization model considered the operational characteristics of wind and solar power and energy storage, constraints of installed capacity, annual curtailment rates, and proportions of wind and solar power generation. Moreover, the constraint of system-load matching deviation was placed to maintain the match between system power outputs and load demand. Then, with the annual output time-series of wind and solar as the input, the optimal capacity proportion of the wind, solar power, and battery energy storage system, which met the optimal source-load matching, was obtained by solving the proposed model. Finally, the effectiveness and practicability of the proposed model and method were verified by testing on an actual regional power grid in the north of China.

Wide-Area Power System Generation-Transmission-Storage Coordinated Planning Method Based on Multiple Flexibility Constraints and Time-Series Simulation

REN Dawei, XIAO Jinyun, HOU Jinming, DU Ershun, JIN Chen, ZHOU Yuanbing

2022, 55(1):  55-63.  DOI: 10.11930/j.issn.1004-9649.202010117

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With the continuous development of global large-scale wind power and photovoltaic power (PV), the net load fluctuations in the system keep intensifying. It creates an urgent need to build a quantifiable and efficient wide-area power system optimization planning model, which can promote the research on planning multiple flexible resources in a wide area. This paper first constructed a time-series operational simulation model considering the output constraints on multiple flexible resources, which is based on a simplified power system unit-commitment model. The capacity of renewable-energy power supply, power grid interconnection, and energy storage in the target level year was optimized, and the analysis process of generation-transmission-storage coordinated optimization planning is summarized. Secondly, the case analysis was performed with the above model, and the capacity of new power generation, power grid interconnection, and energy storage in 2050 was optimized, which was based on the generation-transmission-storage plan of Northeast Asia in 2035. Further, the key issues were elaborated, such as renewable-energy installed capacity, power-grid interconnection capacity, energy storage capacity, the relationship between renewable-energy installed capacity and energy storage capacity, and that between power grid interconnection and energy storage capacity. Finally, some misunderstandings that should be avoided in generation-transmission-storage planning and coordinated optimization suggestions were discussed to provide a technical reference for future planning of a high-proportion renewable energy power system.

Optimal Operation of Multi-Source Power Generation System with Electric Heater and Concentrating Solar Power Plant Considering Conditional Risk Cost

PENG Chunhua, LIU Yi, SUN Huijuan

2022, 55(1):  64-74.  DOI: 10.11930/j.issn.1004-9649.202011068

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With the continuous expansion of the wind farm scale connected to the power grid, the uncertainty of wind power output has brought great challenges to the dispatch of power systems. To this end, this paper relied on the good regulation of concentrating solar power (CSP) and the wind power accommodation of the electric heater (EH) to stabilize the volatility of wind power output and used conditional value-at-risk (CVaR) to measure the uncertainty risk of dispatch cost. For the minimal comprehensive cost under multiple scenarios, an optimal operation model of a multi-source power generation system with the EH-CSP plant considering conditional risk cost was constructed. The elite archiving strategy was adopted, and a differential evolution whale optimization algorithm with the elite archive was proposed to solve the model. The results verify the superiority of the proposed model and method, and the impact of different confidence levels on the scheduling results is analyzed.

Research Overview on the Integrated System of Wind-Solar Hybrid Power Generation Coupled with Hydrogen-Based Energy Storage

JING Tao, CHEN Geng, WANG Zihao, XU Pengjiang, LI Gaochao, JIA Mingxiao, WANG Yueshe, SHI Jinwen, LI Mingtao

2022, 55(1):  75-83.  DOI: 10.11930/j.issn.1004-9649.202012060

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Based on the technologies of wind-solar hybrid power generation, hydrogen generation from electrolysis of water, hydrogen storage, and hydrogen fuel cell, and by taking hydrogen as the core energy carrier, the integrated system of hybrid wind-solar hybrid power generation coupled with hydrogen-based energy storage is expected to be the key routine to the large-scale application of renewable energy-hydrogen energy-electricity energy. In this paper, the current development status about the key technologies were reviewed first including wind-solar hybrid power generation, hydrogen generation from electrolysis of water, hydrogen storage, hydrogen fuel cell and so on. Then the hot topics such as off-grid system, grid system, and capacity configuration optimization for the as-discussed integrated system were analyzed in details. The following progress analysis provided valuable reference for further technical research and engineering application with regard to the integrated system of hybrid wind-solar hybrid power generation coupled with hydrogen-based energy storage.

Medium and Long-Term Hydrogen Load Forecast for Unified Energy System

PENG Shengjiang, SUN Chuanshuai, TUO Jianjun, YUAN Tiejiang

2022, 55(1):  84-90.  DOI: 10.11930/j.issn.1004-9649.202007205

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In the future energy society, hydrogen will play a huge role in power system, industrial application, heating supply, transportation and other fields. Hydrogen energy will be used as the key element of the unified energy system to achieve the energy conversion between various energy sources. In this paper, a method of hydrogen load forecast is proposed for the future demand of hydrogen energy. Firstly, on the basis of the hydrogen load sample data from the industrial field, the characteristics of the load data are calculated and the support vector machine regression (SVR) algorithm is applied to set up the hydrogen load forecast model accordingly. Secondly, a model based on the hydrogen demand data in the heating supply and transportation fields are built as well, and the improved gray GM (1,1) model is utilized in combination with the metabolic model to obtain a hydrogen load forecast model in the heating supply and transportation fields. Finally, all above three hydrogen load forecast are superimposed together to complete the construction of the mathematical model. From the results, not only the SVRT prediction method is proved to be very accurate, but also the combined model group based on the improved gray GM (1,1) model and metabolism have demonstrated high forecast precision. This method is feasible for medium and long-term hydrogen load prediction.

Comparison of Economic Feasibilites Between Power Transmission and Hydrogen Production from an Offshore Wind Farm

HUANG Weijie, JIANG Yuewen

2022, 55(1):  91-100.  DOI: 10.11930/j.issn.1004-9649.202101124

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The rich off-shore wind resources can be exploited to build wind farms with larger installed capacity, which has shown great potential to develop hydrogen energy storage applications. Power transmission and hydrogen production are the two ways to develop and utilize offshore wind power. Firstly in this paper, a life-cycle cost model for offshore wind power transmission is established. Secondly, the energy efficiency calculation process of the proton exchange membrane (PEM) electrolyzer was derived. Based on the "power-efficiency" characteristic model of the PEM electrolyzer, the hydrogen production yield was assessed, and the life-cycle cost model of the off-shore wind power hydrogen production project was formulated. Finally, case studies are conducted to evaluate the economic benefits of these two approaches respectively.

The Day-Ahead Output Plan of Hydrogen Production System Considering the Start-Stop Characteristics of Electrolytic Cell

YUAN Tiejiang, WAN Zhi, WANG Jinjun, ZHANG Duo, JIANG Dongfang

2022, 55(1):  101-109.  DOI: 10.11930/j.issn.1004-9649.202105102

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As one of the main forms of energy in the future, hydrogen has been widely used in social production. Using new energy to produce hydrogen on a large scale is an important technical means to achieve new energy consumption and clean energy utilization. Aiming at the optimization operation of a large-scale intermittent new energy hydrogen production system, a start-stop feature based on electrolyzers is proposed. Day-a-day efforts to optimize the model. Considering real-time electricity price changes, the operating status of multiple electrolyzers, and the intermittentness of new energy sources, and satisfying constraints such as power balance constraints and electrolyzer production constraints, a day-ahead output optimization model of the hydrogen production system with the lowest system operating cost was established. Using actual wind-solar output data and equivalent hydrogen load characteristic data, four different scenarios were constructed to formulate a day-a-day output plan. The results show that the proposed optimized operation strategy can realize the safe and stable operation of the system and avoid large-scale purchase of electricity and alkali at peak electricity prices. The repeated start and stop of the electrolytic cell reduces the operating cost of the system and verifies the correctness of the proposed method.

Research on Business Operation Mode of Hydrogen Integrated Energy System Based on NSGA-II and Entropy Weight Method

FANG Tong, JIANG Dongfang, YANG Yang, YUAN Tiejiang

2022, 55(1):  110-118.  DOI: 10.11930/j.issn.1004-9649.202107102

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Aiming at the cost and benefit problems in the operation of hydrogen containing integrated energy system, a commercial operation method of integrated energy considering energy supply mode is proposed. Firstly, considering each investor, two operation modes, multi link energy supply mode and multi-party cooperative energy supply mode, are proposed; Finally, the energy selling price of each company in the operation process is determined with the goal of the highest net income of the production capacity company and the energy supply company and the lowest price of each energy sold to users; The fast non dominated multi-objective optimization algorithm with elitist retention strategy (NSGA-II) is used to determine the Pareto solution set of the optimal price under each mode. Finally, the entropy weight method is used to determine the weight of each objective function, and the solution set of scheme 1 and 2 which are most popular among the three parties (energy supply company, capacity company and users) is selected, and then the optimal two modes of integrated energy system commercial operation are obtained.

SHACL-Based Validation Method of Knowledge Graph for Power System Model

LI Xiaolu, ZUO Xuan, LIU Riliang, LU Yiming, LI Congli, LIN Shunfu

2022, 55(1):  119-125,228.  DOI: 10.11930/j.issn.1004-9649.202107093

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With the expansion of the power grid and the high penetration of distributed energy resources, the power system analysis and decision-making have put forward higher requirements for comprehensive and accurate power grid models. With respect to frequent version updates of the Common Information Model (CIM) on which the exchange model depends, the inevitable self-defined extension of CIM, and the dynamic evolution of model quality requirements, a method for validating the knowledge graph of the power system model based on the shapes constraint language (SHACL) is proposed. The CIM-based concept graph and entity graph of the power system model are established, the CIM schema consistency shapes, and the cross-class and cross-property consistency shapes based on simple protocol and RDF query language (SPARQL) for validating the power system model are designed. The SHACL-based knowledge graph validation for the power system model does not need to hard-code the validation rules, and then the flexibility of power system model quality validation can be improved and the dynamic evolution of model quality requirements can be satisfied.

Structure and Key Technologies of Big Data Labeling System for Power Equipment Operation Status

LIU Wenjun, DONG Ming, XU Yuanfu, HAN Qiang, WANG Xin, XU Lei, DU Ming

2022, 55(1):  126-132.  DOI: 10.11930/j.issn.1004-9649.202105034

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With the rapid development and deep application of big data analysis technology in power grid, data label technology provides people with a new idea of data integration. Big data labels for power equipment can realize rapid identification and extraction of useful data from massive and discrete data in a flexible way, which not only contributes to make multidimensional judgments on power equipment for power grid operators, but also provides a basis for subsequent power data mining modeling. A multi-dimensional data labeling system for power equipment is proposed, which lays a foundation for realizing intelligent monitoring of power grid.

An Edge Recognition Method for Insulator State Based on Multi-dimension Feature Fusion

HUANG Dongmei, WANG Yueqi, HU Anduo, SUN Jinzhong, SHI Shuai, SUN Yuan, FANG Lingfeng

2022, 55(1):  133-141.  DOI: 10.11930/j.issn.1004-9649.202011120

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Traditional insulator state recognition methods have such problems as poor real-time performance and insufficient feature extraction ability. Based on the idea of edge computing, this paper proposes a method for recognizing the insulator state based on multi-dimension feature fusion. An edge recognition framework for insulator state is constructed using cloud edge collaboration and edge federation collaboration. And a deep learning network integrating multi-dimension feature extraction is designed, which, by using the ResNet101 as the main feature extraction network, uses the Inception module to build the data pooling layer, and embeds the compression incentive module and convolution attention module to extract features from different dimensions. An insulator state recognition experiment is conducted using the data set of normal and defect states, and the average recognition accuracy reaches 99%. The experimental results have proved the validity of the proposed method.

Full Process Modeling and Correction Strategies for Electricity Spot Market Considering AC Feasibility Check

WANG Hongbo, SHAO Lizheng, XIA Qing, FANG Xinxin, CHEN Xiaoting, LIU Hengyi

2022, 55(1):  142-150.  DOI: 10.11930/j.issn.1004-9649.202110044

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The market clearing results of spot market need to be delivered to the generators after passing N-1 security contingency analysis and AC feasibility check. In existing methods, the check procedures are split from pricing model, which leads to the deviation between the market results and the practical operation instructions and incurs uplift payment. To resolve this problem, a study is made on the full-process modeling and correction strategies in spot market. Firstly, a dispatching model with consideration of the power peak shaving requirement is formulated, and it is proved based on the KKT condition that the LMPs can guarantee storage devices’ and traditional generators’ incentive compatibility. Then, an AC power flow based feasibility restoration model is established, which incorporates the restoration cost into the dispatching and pricing model. Finally, under the circumstances of violations, the strategies for market correction and out-of-market correction are proposed to meet different requirements of market clearing time. It is verified with case study that the proposed method can effectively restore the AC feasibility. When there is no time restriction, the market correction method has advantages over other methods. When there is a time restriction, the convex relaxation based out-of market correction method obtains less operation cost and market surplus than the PTDF-based correction method.

Modeling and Analysis of Daily Generation Schedule Considering the Coexistence of Planned Electricity and Market Trading Electricity

ZHANG Shuying, LI Gang, TENG Xiaobi, CHENG Jifeng, YAN Zheng, WANG Han

2022, 55(1):  151-158.  DOI: 10.11930/j.issn.1004-9649.202009107

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With the continuous promotion of China's electricity market-oriented reform, some provinces and cities will gradually introduce market-oriented trading means on the basis of traditional generation schedule. In this context, how to establish the daily generation schedule model considering planned and trading electricity is an urgent problem to be solved. In this paper, a model of daily generation schedule that combines planned electricity decomposition and Nash equilibrium of market trading electricity is established, in which the existing mode of generation schedule is taken into account. By means of solving the model, the daily generation plan was evaluated in two aspects of economy and security, by studying the impact of different market openness. An example simulation of a provincial power grid in East China is given to analyze the impacts of different market trading electricity proportion on the generation cost and power shortage expectation of the whole system, and verify rationality and effectiveness of the proposed model.

Analysis on Operation Performance of Power Market and Clean Energy Transactions in Northwest China

LIU Ruifeng, QI Xiaofang, HE Yuankang, CHEN Tian’en, LUO Xuan, ZHANG Wen

2022, 55(1):  159-167.  DOI: 10.11930/j.issn.1004-9649.202005019

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Aiming at establishing an analytical system of transaction operation performance, covering power market forms, electricity space, market system and market range, this paper makes a multi-dimension statistical analysis of the power transaction operation data based on the power market construction and power transaction operation practices in northwest China. A study is conducted on the main categories of transaction demands of trans-region and trans-province market operations, so as to provide a reference for promoting the power market construction, new energy utilization, and transaction value creation in northwest China. In addition, this paper tries to describe the current overall features of power market transaction in northwest China, so as to provide a reference for market players to better participate in the power market transaction, determine the marketing strategy and make trading decisions. The focus of this paper is put on the trading types and trading mechanisms for improving the utilization level of renewable energy, and some suggestions are proposed to improve the operation quality of the power market.

Multi-objective Flexible Planning of Transmission Network Considering Wind Power and Load Uncertainties

WANG Juanjuan, WANG Tao, LIU Zihan, ZHU Hainan, LI Fengshuo, SUN Huazhong

2022, 55(1):  168-177.  DOI: 10.11930/j.issn.1004-9649.202007274

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Large-scale centralized integration of wind power into power grid significantly enhances the uncertainty of power output in transmission network. In addition, most of the current transmission network planning models adopt DC power flows, which affects the accuracy of planning results. Based on AC power flow, this paper constructs a two-layer model for multi-objective flexible planning of transmission networks considering the uncertainty of wind power and load. The upper-level model is a multi-objective planning model of transmission networks, with consideration of the objective of the annual cost of construction investment, annual network loss and operating efficiency. The non-dominated sorting genetic algorithm-II is used to solve the problem, and the Pareto optimal planning scheme set is transmitted to the lower level. The lower-level model is a multi-scenario checking model with the minimum wind curtailment and load shedding as objective, which is used to test the endurance capacity of the Pareto optimal planning scheme set to the uncertainty of wind power and load. The constraints of the upper model is modified according to the wind curtailment and load shedding expectations, thus transmitting the impact of wind power and load uncertainty to the upper-level model. The AC power flow constraints of the lower-level model is conducted for second order cone relaxation, and the nonlinear nonconvex planning model is transformed into a second order cone planning model with convex feasible region, which is effectively solved using the Cplex solver. Finally, the effectiveness of the proposed model is verified by an adjusted 39-node system.

Collaborative Planning for Distribution Network and PV-ESS in the Marketization Environment

RAO Ping, XIANG Yue, YAO Haotian, LIU Youbo, LIU Junyong

2022, 55(1):  178-188.  DOI: 10.11930/j.issn.1004-9649.202106033

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In the marketization environment of distributed generation, a planning and operation model was proposed given the distributed transaction mechanisms and the economics of energy storage operation strategies for two main purposes. One is to balance the interests of different subjects in the collaborative planning of the distribution network operator (DNO) and the investor of distributed photovoltaic and energy storage system (PV-ESS), and the other is to ensure the benefits of each subject after the planning. Firstly, the benefit coupling model for the subjects in the planning layer was constructed considering photovoltaic prediction errors and agency costs based on the agency transaction mode. Specifically, the settlement rules of agency transactions were formulated on the basis of photovoltaic prediction errors, and the agency cost model was established considering transmission costs of operators, network loss, and reasonable profit. Secondly, a double-layer planning model was established taking the maximization of the investment and planning benefit of the subjects as the optimization goals. In addition, the timing operation results of the distribution network in typical scenes were obtained in the operation layer using the benefit coupling model and energy storage operation strategy. The double-layer improved particle swarm optimization algorithm was applied to run the model. Taking an actual distribution network as an example for the planning solution and analysis, this paper compared the economics of different energy storage operation strategies and analyzed the rationality of the benefit coupling model. The simulation results verify that the proposed method is effective in ensuring the benefits of different subjects.

Numerical Analysis of Operating Characteristics of Frequency-dividing Disconnectors for Distribution Line Surge Arresters

LI Wei, YANG Tingfang, ZHANG Lei, LIU Zhiyong, ZENG Cheng

2022, 55(1):  189-195.  DOI: 10.11930/j.issn.1004-9649.202002112

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In order to reduce the workload of the operation and maintenance of distribution line arresters, this paper designs a frequency-dividing disconnector using double sphere gaps based on the inverse time principle, which can reliably shunt high and low frequency current. The disconnector can be separated automatically and reliably while the insulation of the arrester is damaged, and the fault section can be found. The disconnector realizes the mechanism of frequency division of leakage current by using inductance and large sphere gaps in parallel. Under the impulse or high frequency, the leakage currents flow through the big sphere gap and the disconnector would not act. While under the power or low frequency, the leakage currents flow through the inductor. When the current takes value from 40 mA to 0.5 A, resistance heating action would be utilized. When the current is larger than 0.5 A, the small sphere gap breakdown action would be adopted, which avoids the mal-operation of disconnector due to burned out resistance. In these two cases, the greater the leakage current, the faster the disconnector operates. Through the ATP model simulation, the parameters of the inductance and the operating characteristics of the large gap can be determined. The numerical simulation and experimental results show that the disconnector can operate reliably when the insulation of the arrester is damaged.

Dual-Passivity-Based Control Strategy for Energy Storage Converter under Microgrid Operation Mode Switching

LIU Hui, LEI Yong, ZHU Yingwei, DU Jiayun, ZHOU Wei, YANG Zhixing

2022, 55(1):  196-202.  DOI: 10.11930/j.issn.1004-9649.202004224

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At the unfavorable moments such as island startup, island load switching, and unplanned off-grid, the excessive fluctuation of microgrid bus voltage frequency may seriously damage the electrical equipment of the entire microgrid. The control performance of the energy storage converter selected as the main inverter is vital for maintaining the voltage and frequency stability of the microgrid. Therefore, on the basis of rigorously proving the passivity of the energy storage converter, a dual-passivity-based control strategy suitable for microgrid is proposed to improve the safe and stable operation of the microgrid. A passivity-based control strategy based on the island voltage loop passivity-based controller and the current inner loop passivity-based controller is designed through establishing a port-controlled Hamiltonian model, setting equilibrium points, solving energy matching equations, and correcting damping parameters. The simulation results have verified that the dual-passivity-based control can effectively improve the voltage and frequency stability of the microgrid under islanding/grid-connected operation mode switching, and better ensure the safe and stable operation of the microgrid.

Business Model Iteration System and Method for Energy Internet

LIU Lin, LI Suxiu, ZHANG Hua, ZHANG Xifeng, LIU Yingqi, CHEN Xingtong

2022, 55(1):  203-213.  DOI: 10.11930/j.issn.1004-9649.202102007

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The quick advancement of energy consumption reform and digital economy brings about higher requirements for transformation and development of energy and power enterprises and business model innovation of energy Internet. The business model also needs dynamic innovation, iteration and evolution. Based on the theoretical connotation of business model and iterative innovation, the connotation concept of business model iteration is clarified in this paper. A business model iteration system under the energy Internet is constructed, and the business model iteration path covering "iteration basis, iteration demand, iteration objective, iteration strategy, and overall evaluation" is established, and the iteration mechanism and methods of each link are proposed. Based on the characteristics of energy Internet, the business model iteration system is used to explore the differential application of the iterative system, with focus on three major emerging businesses，including new business of energy transformation, new products of energy digitization and new service of energy platform. Through a case study of virtual power plant and multi-station integration business, a study is made in stage and step on the design and implementation methods of business model iteration. The proposed strategy and method can effectively guide the business model iterative design and perfection of emerging businesses under the energy Internet, and provide theoretical support for innovation and effectiveness verification of business models.

Study on the Trend of China's Electricity Consumption during the “14 th Five Year Plan”

LIU Qing, ZHANG Lili, LI Jiangtao, ZHANG Chenglong, TAN Xiandong, ZHANG Kai, GUO Wei

2022, 55(1):  214-219.  DOI: 10.11930/j.issn.1004-9649.202006284

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At present, China has started the compilation of the "14th five year plan" for electric power development, and the electricity consumption level is an important boundary condition during the 14th Five Year Plan period. Considering the influence factors of power consumption, such as macro-economy and power substitution, the basic and sensitive scheme is set up, and the medium and long-term electricity consumption prediction model is adopted to forecast the electricity consumption level of China during the "14th five year plan". The results show that according to the basic and sensitive schemes, China's electricity consumption in 2025 will be 9.85 trillion and 9.44 trillion kWh respectively, and the average annual growth rate during the "14th five year plan" period will be 5.6% and 4.7% respectively. According to the principle of moderately advanced power planning, it is suggested that the results of the "basic scheme" be used as the boundary conditions of the "14th five year plan" electric power planning.

A New Index and Method for Evaluating Utilization Level of Power Generating Equipment

AN Hongguang, JIN Kunkun, WU Liqiang, DONG Bo, LIU Zhiqiang, LI Yi

2022, 55(1):  220-228.  DOI: 10.11930/j.issn.1004-9649.202103120

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The rapid development of new energy has brought about constant change of electricity generation structure, leading to the inability of the traditional availability hour to directly reflect the utilization level of power generating equipment. A concept of "benchmark availability hour" is thus proposed, and the availability index is defined as the ratio of availability hour to the benchmark availability hour. The reference values for the design availability hour and comparability availability hour are given respectively in the paper, and then an availability index calculation model is proposed. Through comparison of the generating equipment availability hours and availability indexes in different regions and different companies, it is proved that the availability index can factually reflect the utilization level of power generating equipment under the circumstance of generation structure being taken into consideration adequately. This new index and method can be used for power planning and project management.