Table of Content

28 November 2023, Volume 56 Issue 11

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Special Contribution

Problem Identification and Key Measures to Support the Achievement of Carbon Peak and Carbon Neutrality

Guoguang ZHENG

2023, 56(11):  1-8.  DOI: 10.11930/j.issn.1004-9649.202310073

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As the world’s largest developing country and major energy consuming and carbon emitting country, the goal of carbon peak and carbon neutrality (dual carbon) sets higher requirements for China to achieve green and low-carbon economic and social development. Achieving the "dual carbon" goal is a broad and profound economic and social systemic transformation. It is therefore necessary to identify the problems and challenges in achieving the "dual carbon" goal based on a scientific understanding, and the key measures to promote the "dual carbon" work should be proposed. Adhering to the problem-oriented approach, this paper analyzes the sources of "dual carbon" problem, and explores its essence and deep manifestations. Then the paper systematically analyzes the challenges and conditions faced by China to achieve the "dual carbon" goal. On the basis of coordinating development and emission reduction, key measures are proposed to achieve the "dual carbon" goal, including promoting green and low-carbon transformation of energy, advancing energy conservation in key areas, popularizing the application of energy-saving and low-carbon technologies and products, perfecting the system and mechanism for green and low-carbon development, promoting conservation and intensive utilization of resources; enhancing the carbon sink capacity of the ecosystem, and strengthening international exchanges and cooperation.

Offshore Wind Power Transmission and Grid Connection Technology

Probabilistic Forecasting of Offshore Wind Power Based on Dual-stage Attentional LSTM and Joint Quantile Loss Function

Xiangjing SU, Haibo YU, Yang FU, Shuxin TIAN, Haiyu LI, Fuhai GENG

2023, 56(11):  10-19.  DOI: 10.11930/j.issn.1004-9649.202212011

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Probabilistic prediction of offshore wind power is not high in accuracy due to the predetermined threshold limitation of the traditional feature correlation method and the magnitude difference of the quantile loss in each quantile loss. To improve the probabilistic prediction accuracy, a multi-task joint quantile loss-based dual-attention probabilistic prediction model (MT-DALSTM) is proposed. Firstly, a feature and temporal dual attention mechanism is introduced to mine the correlation and temporal dependence among features, and attention weights are given to key features and time point information to improve the accuracy of power prediction. Secondly, during model training, the multi-task joint quantile loss based on task uncertainty is used to improve the final prediction results by dynamically adjusting the proportion of each loss weight. Finally, the simulation validation results based on the real data from the Donghai Bridge offshore wind farm show that the proposed method has significant improvement in sharpness, reliability and comprehensive performance indexes compared to the existing wind power probabilistic prediction studies, which verifies the effectiveness of the model in improving the prediction accuracy.

Economic Analysis of Maximum Cross-Section of Submarine Cables for 66 kV Offshore Wind Farm Collection Systems

Chaohui WANG, Songge HUANG, Bin LIN, Yuwei CHEN, Shumin FAN, Zhaohui SHI

2023, 56(11):  20-28.  DOI: 10.11930/j.issn.1004-9649.202209065

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Topology optimization design of the maximum submarine cable cross-section for offshore wind farm collection systems is an effective means to reduce the total investment of the offshore wind farms and improve the transmission efficiency and system reliability. Since the collection system pooling network has various types of topology and the constraints for selecting the maximum submarine cable cross-section are not considered in the existing optimization studies, there exist low efficiency and high difficulty in the non-convex and non-linear optimization search process of collection system topology, and it is difficult to obtain a global optimal layout scheme. To this end, we propose an economic analysis method for selection of the maximum submarine cable cross-section for 66 kV offshore wind farm collection systems. The constraints for selecting the optimal submarine cable maximum cross-section are added in the process of topology optimization of collection systems through uniparental genetic algorithm and minimum spanning tree technique (MST) to reduce the search space, improve the search accuracy and accelerate the search speed. The results of case study show that it has a significant impact on the economic optimization results to consider the selection constraints of the maximum submarine cable cross-section in the planning of collection system.

Overvoltage Mechanism of 66 kV Submarine Cable Transmission System for Offshore Wind Farm

Xiaohe WANG, Haichao YANG, Shuang SONG, Yuxin YANG, Gui YIN, Ke WANG

2023, 56(11):  29-37, 48.  DOI: 10.11930/j.issn.1004-9649.202208087

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Overvoltage level is the key parameter of the offshore wind power transmission system, which has significant impact on the system design and equipment selection. In order to evaluate the key impact factors of the overvoltage level of the offshore wind farm transmission system and calculate its overvoltage accurately, the overvoltage mechanism of offshore wind farm 66 kV submarine cable transmission system is studied in this paper. Firstly, the topology, control and protection strategy of the 66 kV offshore wind power transmission system are analyzed. And then its overvoltage mechanism is studied from the aspects of fault-free load shedding overvoltage, single phase to ground fault load shedding overvoltage and load-free overvoltage. On this basis, the influence of the neutral point grounding resistance on the overvoltage of the 66 kV transmission system is studied. Finally, a simulation model of the offshore wind power transmission system is established in the PSCAD/EMTDC environment and simulation studies are conducted. The research results show that the grounding resistance of the system and the control and protection strategy of the wind turbine are the main impact factors of the overvoltage level in the 66 kV transmission system. With the variation of the grounding resistance, the control and protection actions of the system will change. The system shows different overvoltage characteristics under different grounding resistance ranges.

Pilot Protection Scheme of Submarine Cable in Flexible Low-Frequency Transmission System Based on Cross Entropy Algorithm

Weixuan HE, Zhengzhen FAN, Yaotong HUO, Yingyu LIANG

2023, 56(11):  38-48.  DOI: 10.11930/j.issn.1004-9649.202306023

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There are power electronic converters on both sides of the AC submarine line of flexible low-frequency transmission system, and the fault current characteristics are determined by the converter control strategy, which is different from the traditional synchronous power supply, which will lead to the risk of incorrect operation of the traditional current differential protection. Based on the fault current characteristics of offshore wind power transmission system cable line, this paper analyzes the operational performance of traditional current differential protection and reveals the reasons for the decline of operational performance. In this paper, a novel pilot protection scheme based on cross entropy algorithm is proposed. In this scheme, virtual negative capacitance compensation and negative number processing are carried out on the sampled current of one side, and then the cross entropy between the sampled current and the current of the other side is calculated. According to the change of cross entropy, external and internal faults are judged. The hardware in-loop test results show that the scheme can operate correctly when various types of faults occur in the submarine cable, and has strong resistance to high transition resistance. It can also operate correctly when there are measurement errors in TA. It can be used as a primary protection for flexible low-frequency transmission submarine.

An Active Frequency Support Strategy for Costal Wind Farms in East China

Jianhua LI, Lu CAO, Renxin YANG, Zhenyan DENG, Zheng LI, Xu CAI

2023, 56(11):  49-58, 112.  DOI: 10.11930/j.issn.1004-9649.202209011

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According to the characteristics of transient frequency response of the East China Power Grid under various operation modes, an active frequency support strategy is proposed for coastal wind farms. Through the PSCAD/EMTDC-based electromagnetic transient equivalent model of the East China Power grid, the requirements of the East China power grid on the support capacity of wind farms under different penetration of renewable energy, and the basic rules of collaborative inertia response with conventional synchronous generators are given. The simulation results show that when the penetration of renewable energy in the East China Grid is higher than 30%, the inertia response of wind power plays an obvious role in increasing the frequency nadir of the grid, and with the rapid growth of the capacity of coastal wind farms, it is indispensable for wind turbines to provide active inertia support; the virtual inertia time constant of wind turbines should be set around the physical inertia time constant of the wind turbines; when wind turbines are needed to participate in the primary frequency regulation (PFR), the pitch system control of wind turbines and the PFR control of synchronous generators should be co-optimized to avoid frequency oscillation. This article can provide a useful reference for the power grid operation under high penetration of non-synchronous power sources.

Technology and Application of Low Power WSN for Electric Power Grid Equipment State Sensing

DDQN Based Resource Allocation Algorithm for Power Sensor Networks

Xueqiong ZHU, Chengbo HU, Jinggang YANG, Yongling LU

2023, 56(11):  60-66.  DOI: 10.11930/j.issn.1004-9649.202305116

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The power sensor network can collect and obtain information on the power grid equipment's working status and working environment in real time, which plays an important role in monitoring and quick response of the grid facilities. Aiming at the special requirements of system such as data queuing time delay and packet loss rate, this paper proposes a resource allocation scheme based on reinforcement learning (RL) for power sensing networks. Under the resource constraints, the scheme optimizes the queuing time and packet loss rate of sensor nodes through the resource allocation algorithms, and the optimization problem is modeled as a Markov decision process (MDP), which is solved by double deep Q-network(DDQN) algorithm. Simulation results and numerical analysis show that the proposed scheme outperforms the benchmark scheme in convergence, time delay and packet loss rate.

Security Protection of Electrical Intelligent Sensors and Sensor Networks

Chunyan AN, Yang LU, Di ZHAI, Xueqiong ZHU

2023, 56(11):  67-76.  DOI: 10.11930/j.issn.1004-9649.202305083

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Security of electrical intelligent sensors and sensor networks is still in the initial research stage, and resource constraints and lack of low-voltage power supply in most application sites make electrical intelligent sensors extremely sensitive to security costs. The widespread user-side deployment makes them more susceptible to physical attacks such as side channel attacks. Besides, new types of security attacks which utilize sensing mechanisms or data processing algorithms are also increasing. Firstly, we analyzed the security requirements of electrical intelligent sensors and networks based on site conditions, service characteristics, equipment capabilities, and industry status quo. And then we established a security technology framework, and reviewed the state-of-the-art research on the security technologies which the electrical intelligent sensors have special needs on, such as sensing security, storage security, lightweight encryption, identity authentication, code and firmware security. Finally, we proposed some development suggestions on the security technologies, which can be used to support the construction of the safe and reliable power database.

Extensible Classification Method for Power Personnel Behavior Based on Pose Estimation

Zhenzhen ZHOU, Yunhai SONG, Yuhao HE, Liwei WANG, Heyan HUANG, Jue HE, Zhihang ZHU, Yunfeng YAN

2023, 56(11):  77-85.  DOI: 10.11930/j.issn.1004-9649.202305046

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Power personnel behavior recognition is a critical component for the safe operation and maintenance of the power system. However, current personnel behavior recognition algorithms, which primarily rely on support vector machines and multi-layer perceptrons for behavior classification, have a number of shortcomings, including low recognition accuracy, insufficient consideration of the interactions between human skeletons, and poor mobility and universality. To address these challenges, we proposes a novel behavior classification decoder based on a self-attention and cross-attention mechanism, which fully considers the associations between human skeletons. Compared to the traditional classification methods, the proposed approach improves the classification accuracy by approximately 10%~20%, and outperforms the deep learning MLP classification methods by more than 2%. To implement behavior recognition, we use a two-stage encoder-decoder architecture method, which has good extensibility while making the decoder suitable for the back end of any pose estimation network. Additionally, we use a grouped decoding method to overcome the quadratic complexity induced by the attention mechanism, which enables the decoder to extend to include more behavior categories, thus being more universal. The proposed behavior recognition algorithm achieves the optimal recognition effect in the personnel image data set based on the substation working scenarios. The comprehensive recognition rate reaches 91.1%, which verifies the efficacy and practicality of the proposed power personnel behavior classification method.

Low-Carbon Planning and Operation for New-Type Power Systems

Multi-objective Cooperative Capacity Determination Method for Integrated System of Wind, Photovoltaic and Storage of Smelting Enterprises Requiring Energy Saving and Carbon Reduction

Wenguang ZHU, Wei WANG, Bin OUYANG, Hua ZHANG, Xin WANG, Rui MA

2023, 56(11):  86-94.  DOI: 10.11930/j.issn.1004-9649.202305047

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Considering the uncertainty of new energy and the carbon emissions of users, a multi-objective capacity determination optimization method for energy storage of smelting enterprises considering economy and cleanliness is proposed. A two-layer energy storage optimization model is established, in which the upper layer model optimizes the energy storage configuration for large users in smelting industry who have installed or plan to install new energy power generation, and the lower layer model optimizes the timing output of energy storage. Firstly, based on the charging and discharging characteristics of wind, photovoltaic and storage, a random uncertainty model of wind and photovoltaic output and a charging and discharging model of energy storage are constructed respectively. Then, a carbon emission accounting model of smelting industry is established to calculate the total carbon emissions and carbon emissions generated by power consumption according to the user output and power load, and the corresponding carbon reduction strategy is given. And then, based on the cost of potential carbon emissions, the maximum economic benefits and minimum cost and total carbon emissions are set as multi-objectives, and the optimal energy storage capacity of enterprises is obtained under the constraints of system safe operation. Finally, taking a copper smelting enterprise as an example, the proposed method is used to optimize the energy storage capacity under the access of wind and photovoltaic with ladder capacity. The simulation results have verified the effectiveness of the proposed method.

Low-Carbon Operation Strategy of Power System Considering Carbon Flow Demand Response

Zhiyuan SUN, Yan SUN, Mosi LIU, Yi SONG

2023, 56(11):  95-103.  DOI: 10.11930/j.issn.1004-9649.202304043

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To address the problem that the traditional low-carbon dispatching methods for power system do not consider the carbon emission reduction potential of users, a low-carbon operation strategy of power system considering carbon flow demand response is proposed to adjust users' electricity consumption behavior and reduce the overall carbon emissions of power system. Firstly, based on the carbon emission flow theory and load-side carbon emission obligation allocation method, a user-side demand response method is established with carbon potential as signal. Secondly, the carbon emission cost is included in the economic cost of power system. Aiming at minimizing the total economic cost of the power system, a low-carbon optimal operation model of power system is established considering the carbon flow demand response. Finally, an IEEE 30 node system is simulated to verify the effectiveness of the proposed method.

Multi-form Flexible Resource Aggregation Model for Virtual Power Plant Based on Grey Target Theory and Spectral Clustering

Xiangxiang LIU, Senlin ZHANG, Siqiao ZHU, Rui MA

2023, 56(11):  104-112.  DOI: 10.11930/j.issn.1004-9649.202304013

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Flexible resources are usually aggregated into virtual power plants to participate in power grid scheduling. A multi-form flexible resource aggregation model for virtual power plant is therefore proposed based on grey target theory and spectral clustering. Firstly, based on the response characteristics of new energy generation, distributed energy storage and flexible loads, the common frequency modulation performance indicators and peak shaving performance indicators are established for each flexible resource from three aspects, including response time, response capacity and daily load fluctuation rate. Secondly, based on the grey target theory, objective weighting method and spectral clustering, the flexible resources in the virtual power plant are classified into frequency modulation resources and peak shaving resources. Finally, a frequency modulation-type virtual power plant aggregation model and a peak shaving-type virtual power plant aggregation model are established respectively, and their post-aggregation response characteristics are studied. The numerical simulation shows that the response time and the daily load fluctuation rate of the post-aggregation virtual power plant are reduced. The peak shaving-type virtual power plants should be used preferentially under peak shaving scenarios. When the peak shaving-type virtual power plants can not meet the peak shaving requirements, the frequency-modulation virtual power plants can participate in peak shaving to improve the utilization efficiency in different scenarios.

Multi-point Synchronous Protection Scheme for Active Distribution Network Based on 5G Communication

Tiecheng LI, Hui FAN, Qian ZANG, Jiangbo REN, Weiming ZHANG, Yibo WANG

2023, 56(11):  113-120.  DOI: 10.11930/j.issn.1004-9649.202304099

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The linear section location method based on remote signaling data does not consider the influence of communication time-delay and reliability, and is only applicable to large current faults and single faults. In this regard, a multi-point synchronous protection scheme for active distribution network based on 5G communication is proposed. Firstly, a section location communication architecture based on 5G communication is established, and its communication time-delay and reliability are analyzed. Secondly, on the basis of analyzing the direction distribution characteristics of the transient zero-sequence current, the switching function is redefined, and a logical relationship location model suitable for small current faults is proposed. Then, using the left-right approximation method, the switching function established according to the logic relationship is linearized, which makes the linearized logic relationship location model not only suitable for single faults, but also for multiple faults. Finally, the proposed protection scheme is validated in an active distribution network with different topologies and 5G communication. The results show that the proposed scheme can not only realize multi-point synchronous protection, but also be applicable to both small current faults and multiple faults.

Fault Diagnosis Method for Operational Security Control System Based on Digital Twins

Wei HAN, Wenyan DUAN, Xingwei DU, Feng YAO, Weidong MA, Lei LIU

2023, 56(11):  121-127.  DOI: 10.11930/j.issn.1004-9649.202306047

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The digital twin technology aims to break through the boundary between virtual and real, achieve organic integration of physical entities and virtual space through virtual real information links, and simulate the real-time state of physical entities. The security and stability control system (security control system) is the second line of defense to ensure the safe and stable operation of the power grid. If it refuses to act or malfunction due to a fault, it will cause serious harm to the operation of the power grid. Therefore, this paper proposes a fault diagnosis method for operational security control system based on digital twins. By analyzing the general operation strategies and possible failure links of the security control system, the digital twin system of the security control system is proposed. And a fault diagnosis model for security control system based on MPA-SVM is established. Finally, the validity and correctness of the proposed method is verified by using the operational data of the security control system to construct the sample datasets.

Power System

Robust Dynamic State Estimation Method for Medium Voltage Distribution Networks Based on Improved Adaptive UKF Algorithm

Junxiang TIAN, Tie CHEN, Bin CHEN

2023, 56(11):  128-133.  DOI: 10.11930/j.issn.1004-9649.202305071

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To address the issues of the lack of real-time measurement, low accuracy of pseudo measurement, and the assumption of constant system state process noise in existing dynamic state estimation (DSE) methods for medium voltage distribution networks, this paper proposes a robust DSE method for medium voltage distribution networks based on an improved adaptive unscented Kalman filter (UKF) algorithm. Firstly, the method uses the smart meter measurement and transformer model at the low voltage side of the distribution transformer in the medium voltage distribution network to derive the equivalent medium voltage measurement to enhance the measurement redundancy of the medium voltage distribution network. Then, this article draws on signal processing technology to update the covariance matrix of system state process noise in real-time and integrates it into the UKF algorithm to reduce the uncertainty of state prediction and measurement filtering, thus proposing a robust DSE method for medium voltage distribution networks based on the improved adaptive UKF algorithm. Finally, based on the constructed 15-buses medium voltage distribution network, simulation results show that the proposed method can effectively perform DSE on the medium voltage distribution network and obtain more accurate situational awareness information.

Power User Load Response Potential Assessment under Fuzzy-Rough Environment

Chaobo GUO, Yibo ZHANG, Hongjiong ZHANG, Kai MA, Lu CHEN

2023, 56(11):  134-142.  DOI: 10.11930/j.issn.1004-9649.202212066

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In-depth exploration of user load adjustment potential is an urgent need for the refined development of the national power market. To effectively perceive the comprehensive load response potential of power users, a hybrid assessment model in fuzzy-rough environment is proposed. Firstly, a load response potential evaluation indicator system is constructed from the dimensions of economy, user load characteristics, and information characteristics. Secondly, the fuzzy-rough number is used to process and aggregate the individual linguistic evaluation information, which fully considers the ambiguity of individual judgment and the diversity of group preferences in the evaluation. On this basis, the fuzz-rough entropy weight method and step-wise weight assessment ratio analysis (SWARA) method are combined to determine the comprehensive weight of the indicators; and the improved multi-attributive border approximation area comparison (MABAC) based on rough-fuzzy numbers is adopted to calculate the comprehensive assessment value of the power user’s load response potential for the attribute function, thereby obtaining the potential ranking result. A case study of load response potential evaluation of power users in multiple industries in Nanjing is presented to illustrate the effectiveness of the proposed model.

Error Status Evaluation Method for Protection Measurement Circuit Based on Improved ED and CM-BPNN Algorithms

Yawen YI, Jingpu ZHAO, Can LIU, Xinxin JIANG, Fangjiu LI, Zhenxing LI

2023, 56(11):  143-150.  DOI: 10.11930/j.issn.1004-9649.202308052

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The accurate evaluation of the error status of the protection measurement circuit can help to understand the operation status of the protection devices, and to timely and effectively find the hidden dangers of the protection devices. This paper proposes an error status evaluation method for substation protection measurement circuit based on improved ED and CM-BPNN algorithms. Firstly, the normalization principle of different index data is formulated for the measurement data. Secondly, the improved Euclidean distance is introduced as the starting criterion for error evaluation. According to the degree of influence on the performance of the protection action, the error status is graded, and the cloud model is introduced to calculate the error status membership degree of the secondary index. Finally, the positioning mapping results corresponding to each error status are determined, and the BP neural network model is constructed, which is then used to evaluate and locate the unknown error status of the current/voltage of the protection devices. Based on PSCAD software, a 220kV substation model was constructed to verify the effectiveness of the proposed method.

Design of DC Composite Electric Field Measurement Structure Based on Vibratory Sensor

Guangzhou ZHANG, Shubo FANG, Zhenyu ZHANG, Zhihui FENG, Qing HAN

2023, 56(11):  151-159.  DOI: 10.11930/j.issn.1004-9649.202207008

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The measurement accuracy of the synthetic electric field of high-voltage DC lines has an important influence on the electromagnetic environment assessment, which is directly related to the environmental protection acceptance of related projects. At present, the most commonly used synthetic field measuring equipment is the rotating field mill tester, whose sensor adopts the structure of rapidly rotating rotor and the mode of carbon brush contacting and grounding. The intermittent contact during high-speed rotation makes the carbon brush grounding unreliable, and the ion accumulation on the rotor leads to the change of electric field and ion current distribution near the measuring point, thus making the measurement results quite different from the actual electric field. In order to solve the inherent defects of the existing grounding mode and rotating structure, based on the measuring principle and structural arrangement of field mill, this paper designs a horizontal reciprocating synthetic field measuring anti-wear vibration sensing mechanism, puts forward the size and arrangement of shielding and induction plates, deduces the sinusoidal relationship between the synthetic electric field and the induced current, draws the modulation waveform of the induced signal, analyzes the amplitude and phase relationship between the synthetic field and the ion flow field, and determines the rotating speed of the rotating motor to be 4 800 r/min and frequency 80 Hz through the limit value of wind speed measurement condition. The results show that the stator plate grounding of the horizontal vibration structure eliminates the accumulation and distortion of ion current; the connection of micro ball guide sleeve can effectively reduce mechanical wear; and the sensor has good linearity, which can meet the requirements of field measurement.

Principle of Supraharmonic Elimination Based on Random Carrier Sinusoidal Pulse Width Modulation for Converter Clusters

Jiawei YANG, Yang YI, Hao JIANG, Lin ZHU, Zhiwei YAO

2023, 56(11):  160-167.  DOI: 10.11930/j.issn.1004-9649.202308013

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It is established by the voltage source converter supraharmonic model based on the principle of RC-SPWM. The relationship among the carrier randomness and amplitude as well as the phase randomness of supraharmonic is explored. The supraharmonic spectrum is distributed over a wider frequency range, and the amplitude of each supraharmonic approximates a normal distribution feature. The phases of supraharmonic approximate a uniform distribution feature due to the randomness of the carrier wave. The mechanism for supraharmonic elimination for converter clusters without carrier synchronization based on RC-SPWM is proposed, where the purpose of suppressing supraharmonic in a wide frequency range can be achieved. The simulation and experimental results demonstrate the effectiveness of the proposed supraharmonic elimination mechanism.

Parameter Design of SOC Balance Control for MMC-BESS Engineering Applications

Xuefen JIN, Jianhui JI, Lanfang LI, Qinan LI, Fan ZHANG, Xiong ZHAN, Junwei HUANG

2023, 56(11):  168-176.  DOI: 10.11930/j.issn.1004-9649.202304076

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In view of the engineering application of MMC-BESS technology, this paper provides theoretical basis and practical steps and methods for SOC balance control parameter design from four dimensions of modulation, efficiency, submodule capacitor voltage balancing, and device selection. To improve the speed of SOC balance control, the SOC balance control method of setting different control parameters in sections between submodules in the bridge arm is proposed. Based on the proposed demonstration project, the control parameters are designed. In addition, the rationality of control parameter design and the effectiveness of segmented control parameters to accelerate SOC balance control are verified by simulation.

Inspiration of the UK ESO Power Supply Sustainability Measures under European Energy Crisis to China Power System Operator

Rui ZHU, Zhuoran LIU, Xiaoling JIN, Yuyao SHI

2023, 56(11):  177-184.  DOI: 10.11930/j.issn.1004-9649.202308040

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The conflict between Russia and Ukraine has brought profound changes to the European energy market, and the security of the electricity supply of the UK national grid in the winter of 2022-2023 has been severely challenged. Before the arrival of winter, the UK power grid has fully considered the extreme situation of the blocked supply of primary energy and the uncertainty of the power support capacity of the European continent, and put forward targeted countermeasures, which are released to the society in the annual report on the preparations for the peak of winter power demand, achieving positive results. From the de facto situation of separately-operated source and grid, gradually-matured power system and mechanism, and occasional conflicts in regional supply and demand structures in China, this kind of analysis of energy and power supply based on grid enterprises is very necessary, and it can provide sufficient reference for guaranteed power supply under the construction of new power system in China, in terms of the analysis paradigm of extreme scenarios, adequate reserve of emergency resources, and timely release of public information. It is suggested that the various source-grid-load players in market and the government departments work together, and achieve further progress in the operation simulation of power system under extreme conditions, the preparation of demand-responsive resources and the improvement of information transparency.

New Energy

Multi-stage Dynamic Plan of Regional Integrated Energy System Considering Medium and Long-Term Carbon Emission Reduction Constraints

Xiaofei WANG, Hongbo REN, Qiong WU, Qifen LI

2023, 56(11):  185-196.  DOI: 10.11930/j.issn.1004-9649.202211028

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On a long-term scale, internal technological innovation and external environmental impact make the operation scenario of an integrated energy system increasingly complex. Based on the economic optimal configuration of regional energy resources and carbon emission reduction requirements, this paper proposes a multi-stage dynamic planning model for integrated energy systems considering medium and long-term carbon emission reduction constraints. The model can preset flexible stage division rules and different carbon emission reduction modes, and the optimal equipment allocation scheme is obtained by using a mixed integer linear programming method with the objective of minimizing the overall regional energy supply cost in the planning cycle. At the same time, a learning curve model is introduced to predict the change trend of equipment cost during the planning cycle, and new carbon reduction means such as hydrogen energy and carbon sink are considered. The simulation results for typical cases show that the increase in the number of planning stages achieves more effective dynamic matching of supply and demand, and the system economy and emission reduction effect are effectively improved. At the same time, different carbon emission reduction constraint patterns will lead to different carbon emission paths, which need to consider regional carbon reduction targets for the reasonable setting of emission reduction constraints.

Multi-verse Optimization-based MPPT Design for PV-TEG System

Dahu LI, Hongyu ZHOU, Yue ZHOU, Yuze RAO, Wei YAO

2023, 56(11):  197-205.  DOI: 10.11930/j.issn.1004-9649.202210127

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A centralized hybrid photovoltaic thermoelectric generator (PV-TEG) system shows multiple local maximum power points (LMPPs) under a partial shading condition (PSC). The multi-verse optimization (MVO) is used for the maximum power point tracking (MPPT) of the PV-TEG system under PSC. MVO can effectively identify the unique global maximum power point (GMPP) among multiple LMPPs by balancing global search and local search, avoiding search results trapped in LMPP and improving generation efficiency and energy utilization. The simulation results of the example show that the MPPT based on the MVO algorithm can collect higher power in a shorter time and achieve the minimum power fluctuation.

Integrated Energy System Optimization Considering EnergyCommunities with Prosumers

Jiguang KANG, Jiehua JU, Yanmin ZHAO, Yutong ZHAO, Xuetao BAI, Yingru ZHAO, Rui JING

2023, 56(11):  206-216.  DOI: 10.11930/j.issn.1004-9649.202209073

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The rapid development of distributed renewable energy gradually transforms energy users to prosumers. Energy communities coordinate the local energy distribution and help users to trade energy, which provides a new direction for energy systems to improve its efficiency and reduce energy cost. Most existing researches either focus on integrated energy systems (IES) design but without considering energy trading among users, or focus on energy trading but without consideration of meeting the users’ multi-energy demand. Therefore, this study proposes an optimization approach for IES considering energy communities with prosumers. Taking the integrated energy service providers and uses as different stakeholders, an energy community trading model is established based on the bid-response mechanism, and the optimal design and operation schemes of IES are studied with the aim to maximize economic benefits. The case study results indicate that users can efficiently shift the peak demand through energy trading, and reduce the energy cost and gain profits by trading within the energy community. Meanwhile, the prosumers within energy communities can reduce their dependence on the upper-level energy system through energy trading and coordination, subsequently mitigating the impact of local renewable energy generation on the upper-level energy system.

Energy Conservation and Environmental Protection

Quantitative Evaluation of Wet Desulfurization Slurry Quality and Spray Layer Operation in Coal-fired Power Plants

Long JIANG, Liang CHENG, Jinjing LI, Qing LI

2023, 56(11):  217-225, 235.  DOI: 10.11930/j.issn.1004-9649.202211064

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With the help of the big data analysis method and the operation experience of the wet desulfurization process, the key parameters such as the quality of the desulfurization slurry, the blockage probability of the spray layer, the leakage probability of the spray layer, and the gypsum supersaturation of the desulfurization slurry that cannot be monitored and evaluated in real time during the desulfurization operation were quantified, and specific qualitative evaluation rules were provided to better judge and guide the safe operation of the wet desulfurization. The constructed index was applied to a 1 000MW unit in North China. When there are operational operations that affect the quality of desulfurization slurry, such as replacing limestone or replacing desulfurization slurry, the developed desulfurization slurry quality index calculation value could quantitatively reflect the changes in desulfurization slurry quality; The probability of clogging and leakage of the spray layer were consistent with the operation status of the spray layer during maintenance; The gypsum supersaturation value of the desulfurization slurry of the unit was maintained at about 1.10 for a long time, and there was no scaling risk, which was consistent with the fact that there was no obvious scale on the filter screen surface and inner wall surface of the desulfurization tower during maintenance.

Application Analysis of Flue Gas Condensation Recovery in Coal-fired Power Plants by Spraying Method

Chao YI, Da TENG, Shaowei SONG, Ou CHEN

2023, 56(11):  226-235.  DOI: 10.11930/j.issn.1004-9649.202302007

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The flue gas reaches wet saturation state after wet desulfurization tower in coal-fired power plant, and directly discharged will lead to large amount of moisture loss. Taking flue gas water recovery system as the research object by the direct spraying method, and explores the characteristic parameters of the flue gas containing water saturation, and builds an integrated device integrating with the flue gas desulfurization, water recovery and deep emissions reduction, and analyzes the operation performance. The results show that the saturated flue gas moisture content varies greatly with the flue gas temperature, and the higher the flue gas temperature, the higher the moisture content. The flue gas water recovery is obviously affected by the cold source medium. The theoretical flue gas water recovery rate is determined by the flue gas import/export moisture content and flow. The actual flue gas water recovery rate is up to 453.62 t/d, and the highest water recovery efficiency is 26.44%. The direct spraying method reduces dust emission concentration by 66%~80% and sulfur dioxide emission concentration by 50%~60%. The research results provide engineering guidance for the flue gas water recovery and utilization.

Technology and Economics

Optimal Energy Trading Strategies for Local Electricity Markets with Multiple Distributed Energy Resource Aggregators

Chuihui ZENG, Wenzheng LI, Baowei LI, Jun XIE

2023, 56(11):  236-245.  DOI: 10.11930/j.issn.1004-9649.202307063

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Distributed energy resources are small-scale and widely-distributed, which make them unable to directly participate in the energy trading. Therefore, it is proposed by an optimal energy trading strategy for local electricity market with multiple distributed energy resource (DER) aggregators. Firstly, scattered DERs are formulated as aggregators to participate in the energy trading of the local electricity market, and distribution system operators participate act as system owners to participate the energy trading of the local electricity market and the wholesale market of the upper grid. Secondly, a two-tier model of optimal energy trading in local electricity market with multiple DER aggregators is established. Finally, the Karush-Kuhn-Tucker (KKT) condition, the strong duality theory and the big-M method are adopted to transform the proposed model into a single layer model. The simulation results show that the proposed model can effectively promote DER to participate in energy trading and improve the operation efficiency of the overall power system.

Cognitive System and Key Issues of Green and Low-Carbon Production Mode and Life Style

Jing HU, Hu YAN, Ning ZHANG, Bibin HUANG, Rui CHEN, Ning CHEN, Dian WANG, Jing LU

2023, 56(11):  246-254.  DOI: 10.11930/j.issn.1004-9649.202304090

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The green and low-carbon production mode and life style have significant impacts on the ecological civilization construction, and the 21st CPC National Congress proposed to "promote the formation of green and low-carbon production mode and life style". Firstly, focusing on how to recognize and build green and low-carbon production mode and life style, this paper proposes a cognitive system of green and low-carbon modes of production and life. Secondly, from the perspective of energy, economy and society, this paper also puts forward the typical scenarios and typical modes for energy and electric power to promote terminal green energy use, the green cost sharing mechanism based on the green cost transmission and allocation in the industrial chain, and the green behavior cultivation mechanism based on Maslow's hierarchy of needs model, respectively, which can comprehensively support the construction of green and low-carbon production mode and life style.