Electric Power

Planning and Assessment Method of Large-Scale Electrochemical Energy Storage in Power Grids Considering Battery Aging

QI Buyang, ZHUO Zhenyu, DU Ershun, ZHANG Ning, KANG Chongqing

2023, 56(8): 1-9,47. DOI: 10.11930/j.issn.1004-9649.202212068

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China will strive to peak carbon dioxide emissions before 2030 and achieve carbon neutrality before 2060, which requires the development of a power network with high penetration of renewable energy generation. With the addition of new types of load technologies and larger peak-valley difference due to the development of economy, the uncertainty and unbalance between generation and load becomes a salient problem for low-carbon power networks. Energy storage devices can provide flexibility to such power networks and are considered to be a vital part in the construction of low-carbon power systems. In this research, a planning method for large-scale electro-chemical energy storage devices in networks considering battery ageing is developed, and the assessment of energy storage based on simulation is performed. This method can provide guidance for the configuration of energy storage devices in future low-carbon power networks. The addition of energy storage can lower the cost of system operation and decrease the emission of greenhouse gases. The reliability of the system and the ability of renewable energy consumption can be enhanced.

Research on Alternative Effect Evaluation and Policy Mechanisms of Grid-Side Functional Alternative Energy Storage

HU Jing, HUANG Bibin, MENG Zihan, LI Nana, JI Zhe

2023, 56(8): 10-16. DOI: 10.11930/j.issn.1004-9649.202304094

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In recent years, China has issued several policies to support the development of new energy storage, which has entered the fast track of development. As an important application form, grid-side functional alternative energy storage can replace or delay the construction of transmission and transformation facilities in the power system. The national policy clearly supports the development of grid-side functional alternative energy storage and proposes to explore the inclusion of power transmission and distribution price dredging costs. At present, grid-side functional alternative energy storage is in the initial stage of exploration, and the relevant policy management mechanism is not mature. This paper clarifies the definition scope of grid-side functional alternative energy storage, puts forward the alternative effect evaluation method of grid-side functional alternative energy storage, and carries out the analysis and demonstration of typical cases. The paper also proposes the cost dredging mechanism of grid-side functional alternative energy storage at different development stages of the power market and provides relevant policy suggestions, so as to promote the orderly development and efficient utilization of grid-side functional alternative energy storage.

Research on Development Potential and Path of New Energy Storage Supporting Carbon Peak and Carbon Neutrality

REN Dawei, HOU Jinming, XIAO Jinyu, JIN Chen, WU Jiawei

2023, 56(8): 17-25. DOI: 10.11930/j.issn.1004-9649.202303034

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The construction of a new power system is crucial to achieving the goal of carbon peak and carbon neutrality. The flexible regulation ability of the system has become a key factor in building a new power system. The new energy storage has many advantages, and the technical economy is progressing rapidly, which will become an important support for improving the flexible adjustment ability of the system. The amount and the type of new energy storage and the way to develop new energy storage are the key research topics for the new power system to support the realization of carbon peak and carbon neutrality in the future. This paper attempts to combine the transformation path of China’s power system, the collaborative planning of flexible resources, the development of energy storage technology, and the characteristics of China’s power system. Based on the transformation path scenario, three new energy storage research schemes are proposed with full consideration of the uncertainties in the development process of coal power. The source-grid-load-storage expansion optimization model of the power system based on time series production simulation is adopted to fully describe the system characteristics of power supply, load, and grid interconnection of seven regional power grids, comprehensively consider the technical and economic characteristics of system flexible resources, and quantitatively analyze the demand potential of the seven regional power grids in China for various types of energy storage. The development path of new energy storage is proposed from the dimensions of the development task, technical and economic level, and development scale of new energy storage in terms of three stages of carbon peak, rapid emission reduction, and carbon neutrality, which provides decision-making reference for the development planning of new energy storage and the sustainable development of industry in China.

Master-Slave Game-Based Robust Pricing Method of Shared Energy Storage Considering Renewable Energy Accommodation and Energy Storage Participating in Frequency Modulation

QI Caijuan, CHE Bin, YANG Yan, CHEN Baosheng

2023, 56(8): 26-39. DOI: 10.11930/j.issn.1004-9649.202301004

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For the unclear trading mechanism of large-scale energy storage application and the difficulty in recovering investment costs, this paper proposes a pricing method for shared energy storage. A distributionally robust pricing model based on master-slave game for shared energy storage with shared energy storage operators as leaders and wind farms as followers considering energy storage participating in frequency modulation is built. The upper layer aims at maximizing the profit of shared energy storage operators. It is proposed that energy storage can not only benefit from wind farms but also obtain revenue by participating in system frequency modulation. The lower layer aims at maximizing the revenue of wind farms and builds a two-stage distributionally robust optimization model of wind farm considering the uncertainty of wind power. The first stage maximizes the revenue of electricity sales in the basic scenario, and the second stage minimizes the penalty cost expectation of wind farm grid deviation under uncertain scenarios. An example is designed and simulated based on the actual wind farm operation data in Northwest China. The results show that the reasonable pricing strategy of shared energy storage operators is not only conducive to improving the regulation capacity of new energy stations and reducing wind abandonment, but also increasing the utilization rate of energy storage and achieving mutual benefit and win-win results for both parties in the game.

Seasonal Energy Storage Capacity Planning for Provincial Region Considering Unbalanced Seasonal Renewable Energy Generation

WU Zhen, HUO Yanda, ZHANG Yi, HUANG Julong, DAI Jianfeng

2023, 56(8): 40-47. DOI: 10.11930/j.issn.1004-9649.202301047

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With a high penetration of renewable energy, the new power system is facing the challenges of uneven seasonal power supply caused by renewable energy, and the stability of the power supply in the system is threatened. As a new flexible regulation resource, seasonal energy storage can realize long-term and large-scale energy transfer, which can be used to balance the seasonal power outputs. Reasonable allocation of seasonal energy storage at the planning stage can ensure the balance of monthly electricity and reduce the pressure on the power supply. In this paper, a planning method for seasonal energy storage is proposed. Firstly, based on the monthly meteorological information, the seasonal model of renewable energy is established. Then, by taking the minimum annual comprehensive cost of the system as the objective function and considering the operation constraints of various types of power supplies, energy storage planning/operation constraints, and annual/monthly power balance constraints, the seasonal energy storage calculation model is established to calculate the seasonal energy storage capacity. Finally, the 2050 planning scheme of a province in South China is used as an example to verify the effectiveness of the proposed method.

Bidding Strategy of Energy Storage Participating in the Auxiliary Market of Peak and Frequency Modulation in New Power System

YU Haibin, DONG Shuai, LU Zengjie, ZHOU Yi, WEN Guanglei, ZHANG Yu, GAO Yiling, LI Xueyan

2023, 56(8): 48-60. DOI: 10.11930/j.issn.1004-9649.202301059

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Under the green and low-carbon energy transition, the gap of peak and frequency modulation in the power system is increasing. With the flexible climbing and bidirectional regulation characteristics, energy storage can be an independent subject or an internal member of a virtual power plant (VPP) to coordinate and solve the problems of peak and frequency modulation and new energy consumption. This paper analyzes the general situation of energy storage participating in the electric power market in China and abroad and establishes the VPP aggregated multi-distributed energy resource (DER) peak modulation bidding model and peak modulation bidding strategy with maximum overall benefit. Based on the joint clearing model of the electricity energy and frequency modulation market with the goal of minimizing the cost of power generation and frequency modulation, an efficiency factor is introduced to reflect the advantages of fast frequency modulation resources. An example is given to verify that the income of energy storage distribution under the VPP bidding strategy is better than the independent operation mode. Compared with the sequential clearing mode, the fire-storage combined clearing model of traditional and fast frequency modulation trading varieties participating in the day-ahead market design has higher social benefits. The introduction of the efficiency factor can enhance the enthusiasm of high-quality frequency modulation resources to participate in the market and save the total frequency modulation cost of the power grid.

Trust Mechanism Based Secure Cluster Head Election Algorithm for Electric Power Wireless Sensor Networks

WEI Lei, XU Jiangtao, GUO Yajuan, ZHU Daohua

2023, 56(8): 61-67,76. DOI: 10.11930/j.issn.1004-9649.202211086

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Wireless sensor network (WSN) is increasingly applied in sensing and monitoring scenarios, but a large number of sensor nodes usually face high security risks. Having limited resources and weak security protection, sensor nodes are vulnerable to malicious attacks such as selective forwarding, forgery and tampering of data in collecting data, resulting in unnecessary damage to the system. A trust mechanism based secure cluster head election algorithm is thus proposed for wireless sensor networks. Considering the historical communication records, data consistency, the distance between nodes in the cluster and the distance between base stations, as well as the communication quality and energy consumption, the safe and reliable cluster heads are elected as the aggregation node of the current cluster. At the same time, the fairness of energy consumption of selected cluster head nodes is guaranteed by time cycle rotation. Finally, the simulation results show that the algorithm can effectively avoid the malicious nodes being selected as cluster heads and improve the security of wireless sensor networks.

Coverage Optimization Technology of Power Pipe Gallery Based on Improved Gray Wolf Algorithm

ZHONG Cheng, ZHAI Di, LU Yang, LIU Xiaobo, WANG Xinru, ZHAO Xiongwen

2023, 56(8): 68-76. DOI: 10.11930/j.issn.1004-9649.202303023

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To address the problem of reduced communication quality in narrow underground power pipe gallery, where wireless sensor network coverage is affected by irregular shapes, obstacles, and electromagnetic interference, a power monitoring coverage sensing model is constructed based on the minimum access rate constraint, and an improved gray wolf coverage optimization algorithm is proposed by combining neuron mapping and differential evolution. Firstly, a uniform initial population is generated by neuron chaos mapping. Then, the nonlinear convergence factor is used to balance the global and local search ability. And finally, a differential evolution algorithm is introduced to mutate the gray wolf individuals. A comparative simulation analysis is made of various coverage optimization methods, and the results show that the proposed algorithm has robust search capabilities and it can significantly improve the network coverage performance in the narrow underground power pipe galleries, while effectively satisfying the communication needs of the monitored nodes.

Resource Allocation for Edge-enhanced Distributed Power Wireless Sensor Network

WU Gang, ZHOU Jinhui, LI Hui

2023, 56(8): 77-85,98. DOI: 10.11930/j.issn.1004-9649.202304069

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Aiming at the problems of high access latency, high energy consumption, and deteriorating user service quality in traditional wireless power sensor networks, the mobile edge computing (MEC) is introduced to establish a joint optimization model of access latency and network energy consumption, with objective to minimize the joint function of latency and energy consumption. Then, the total resource processing capacity of the central unit/distribution unit is determined by controlling the waiting latency in the load transfer process under the common constraints of the remaining resources of the RF remote unit, the load queuing latency, and the remaining resources of the central unit/distribution unit. And then, based on the resource utilization of the MEC server, the energy consumption of the sensor devices is reduced by reducing the number of active MEC servers. The influence of the weight coefficient on the objective function and the comparison of the algorithm under different traffic flows and times are analyzed. The results show that the proposed allocation mechanism is better than other comparison algorithms in reducing access latency and energy consumption. Therefore, this mechanism can effectively improve the communication quality of the sensors and the efficiency of the system, extend the life of the sensor equipment, and reduce the network cost.

Adaptation of Digital Perception Service and Communication Technologies for Local Communication Network of Urban Grid

ZHONG Cheng, ZHAI Di, LU Yang, FAN Jingyi, LIU Xiaobo, ZHANG Xinyue, ZHAO Xiongwen

2023, 56(8): 86-98. DOI: 10.11930/j.issn.1004-9649.202304068

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In view of the requirements of the differentiated new local digital power perception service for communication performance, the adaptation of flexible and reasonable communication technology is essential to establish a safe, reliable and economic power communication network. Aiming at the new local digital perception scenarios of the new power system, an analysis is firstly carried out on the requirements for the communication performance of the typical local communication technology and power business, and a multi-level and multi-dimensional comprehensive evaluation model is constructed. Secondly, a combined subjective and objective weighting method by fuzzy analytic hierarchy process-entropy weight based on correlation coefficient is proposed to determine the weights of indexes. And finally, the best fit-technique for order preference by similarity to ideal solution (BF-TOPSIS) is used to calculate the weighted evaluation scores to obtain adaptation results. The results show that the proposed evaluation model and adaptive algorithms can provide a theoretical basis and solutions for matching between new local digital power perception services and local communication technologies.

Online Detection Method of Open Circuit Fault of Rotating Diode in Multi-phase Brushless Exciter

WU Yucai, SUN Shuqiong

2023, 56(8): 99-108. DOI: 10.11930/j.issn.1004-9649.202303043

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Aiming at the open-circuit detecting difficulty of the rotating diode of polyphase brushless exciter, the 39-phase-11-pole brushless exciter is taken as the example in this paper, the armature current characteristics of the brushless exciter during normal operation and single-tube open-circuit fault are analyzed. Firstly, the change law of armature magnetic field in two states is analyzed, a magnetic field detection coil is proposed to be installed on any pole of the stator in the exciter according to the structural characteristics of the exciter and electromagnetic coupling relationship. Then, combining with the harmonic characteristics of the spatial magnetic field of the brushless exciter, the flux expression of the detection coil is derived, and the induced voltage of the detection coil could be obtained. Specifically, it is found that an open diode fault causes a change in the amplitude of a specific frequency harmonic in the induced voltage. Finally, the finite element simulation proves that the detection coil method can effectively identify the rotating diode open circuit fault without affecting the normal operation of the brushless exciter.

Passive Sliding Mode Control Strategy for PCHD Model of MMC in Unbalanced Power Grid

LIU Daobing, BAO Miaosheng, Li Shichun, Guo Hancong, Guo Yingying, Qi Yue

2023, 56(8): 109-116. DOI: 10.11930/j.issn.1004-9649.202302084

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When the voltage of the power grid is unbalanced, the DC transmission and distribution system using modular multilevel converters (MMC) as converter devices will encounter problems such as AC current asymmetry and secondary pulsation of active and reactive power. Therefore, a hybrid control strategy of passive based control (PBC) and sliding mode control (SMC) based on port controlled dissipative Hamiltonian with Dissipation (PCHD) model is proposed. A passive sliding mode variable structure controller for MMC control system under PCHD model is designed further. Through simulation, it is verified that the proposed method has better control performance than common methods such as PI control and passive control.

Expansion Planning Method of Power Grid with Wind Power Considering Optimal Switching and Current Limiting

DONG Shuwen, LIU Baozhu, HU Junjie

2023, 56(8): 117-125,142. DOI: 10.11930/j.issn.1004-9649.202303056

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In order to address the new challenges brought by the large-scale integration of new energy into the power system represented by wind power, a wind power grid expansion planning model considering line optimization, switching, and current limiting is proposed. First of all, from the perspective of conventional thermal power unit startup and shutdown caused by system load change, the short circuit current constraint in typical scenarios is converted into the constraint under the corresponding unit startup and shutdown status. The equivalent expression of wind farm is studied by the structural equivalence of wind farm’s power collection system, and the short circuit current constraint considering the wind power connection is introduced. Secondly, by determining the overall idea of power grid expansion planning and taking the minimum total investment as the objective function, the mixed integer linear programming model of power grid planning is established and solved that comprehensively considers the energy storage, demand-side response and short-circuit current constraints. Finally, taking IEEE-RTS 24-node system as an example, the effectiveness of the proposed method is verified by setting different cases for comparative analysis.

Current-Harmonic-Based Active Damping Strategy

XU Jia, YANG Shude, ZHANG Xinwen

2023, 56(8): 126-135. DOI: 10.11930/j.issn.1004-9649.202303004

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The voltage-harmonic-based active damping control (VHBAD) can improve the adaptability of the converter to the weak grid, but it will weaken the suppression ability of background harmonic voltage disturbance and affect the quality of grid-connected current. For this reason, the mathematical model of the grid-connected converter to the weak grid is established first, and the influence of the grid equivalent inductance on the system stability is analyzed. Then, a current-harmonic-based active damping (CHBAD) strategy is proposed. This strategy moves the action point of the active damping branch from the reference signal to the output of the regulator, which can improve the adaptability of the converter to the weak grid and ensure the quality of grid-connected current. Finally, the simulation model is built by simulation software, namely Plecs, and the time domain simulation results are consistent with the theoretical analysis, which verifies the effectiveness of the strategy.

Day-Ahead Optimal Dispatch for Active Distribution Network Considering Action Cost of Devices

YUE Yuanyuan, WANG Zhuding, WANG Hui, LUO Xuan, SU Zhou, HUI Zijia

2023, 56(8): 136-142. DOI: 10.11930/j.issn.1004-9649.202208112

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In order to reduce the cost of active distribution network day-ahead optimization scheduling, a method of active distribution network day-ahead optimization scheduling considering equipment adjustment cost is proposed. Establish a daily optimal scheduling model with the objective function of minimizing the comprehensive operating cost and the constraints of Distflow branch power flow and equipment safety operation. A new linearization method is proposed to form a mixed integer Linear programming model for nonlinear items such as node voltage fluctuation constraints and energy storage life cost model in the form of Second-order cone programming (SOCP). Simulate and calculate in an improved IEEE-33 node system using the YALMIP/CPLEX tool. The experimental results show that the proposed method can effectively consider the cost factor of energy storage life loss, and the effect is good.

Probabilistic Load Forecasting Method of High Voltage Substation Based on Hierarchical Measurement Data

TANG Xuchen, CHAO Zhu, DUAN Qinwei, SU Binghong, CHEN Huican

2023, 56(8): 143-150. DOI: 10.11930/j.issn.1004-9649.202209110

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In recent years, the continuous upgrading and improvement of measurement systems at all levels in the power system makes it possible to further improve the accuracy of load forecasting in high-voltage substations. Based on the multi-level load data of high-voltage substation and its auxiliary medium voltage outgoing line and medium voltage distribution transformer, the paper proposes a bottom-up probabilistic load forecasting method based on medium voltage outgoing line and medium voltage distribution, analyzes the distribution characteristics of the results and completes the load accumulation. In addition, in order to improve the prediction accuracy, the probability prediction method is used to correct the prediction deviation caused by network loss and measurement error. The results of example analysis show that the comprehensive evaluation of the proposed method is better. It can not only get high accuracy load point forecasting results, but also delimit smaller forecasting intervals.

Method of Load Forecasting in Microgrid Based on Differential Expansion of Small Sample Data

JIA Wei, HUANG Yuchun

2023, 56(8): 151-156,165. DOI: 10.11930/j.issn.1004-9649.202209035

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For load forecasting in renewable energy microgrid, aiming at the problem that the prediction accuracy is not high because of the lack of sample data in mid- and long-term load forecasting. This paper proposes a new data expansion method. The original data sample is used as a new data sample, and the data is filtered by setting a threshold. The data sample is expanded while ensuring the accuracy of the data, and the data based on the difference operation is analyzed. The capacity expansion method can eliminate the uncertainty of load data. Considering the influencing factors such as meteorology and population, using multiple regression analysis to fit the impact of various related factors on the load, the original data load forecasting model was used as a control, and practicality and accuracy of the expansion method in this paper was verified by comparing the error between the predicted result and the actual load.

Parameter Estimation for Line Impedance in Distribution Network Based on μPMU Data

ZHANG Zitong, ZHOU Qun, DIAN Yulin, GUAN Zichao, YIN Yue, LENG Minrui, LIU Xueshan

2023, 56(8): 157-165. DOI: 10.11930/j.issn.1004-9649.202212097

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In order to solve the long standing issue of missing line impedance parameters in low voltage distribution network, this paper proposed a new approach based on measurement data collected from the micro-synchronous phasor measuring unit (μPMU). Firstly, by taking line impedance parameters as variables, the root node state value of the station area is calculated from the measurement data. And then by setting the objective function as the minimization of the difference between the calculated value and the measured value, the solution for impedance parameters is converted to a multi-objective optimization problem. Moreover, through designed experiments the weight coefficients of the objective function and the size of the dataset are determined appropriately to reduce the influence of errors on the solution results such that the model can be solved with higher accuracy. Finally, an example of a low voltage distribution network with 26 load nodes and 34 line branches is set up. Considering the actual measurement error, the average error of the line impedance parameter estimation is 3.87%. The case study results show that the proposed method achieves accurate estimation of the impedance parameters and hence the effectiveness of the proposed model is verified.

Sending-Terminal DC Power Grid in Western China and Its Operation Characteristics in the Context of New Power System

LI Huiling

2023, 56(8): 166-174. DOI: 10.11930/j.issn.1004-9649.202212103

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Inevitably China will encounter the enormous demand of large-capacity power transmission over long-distance transmission from the west to the east in the future. With regards to such emerging requirement, a cluster-connected western sending terminal DC grid based on VSC-HVDC is constructed in this paper such that the complementary regulation is performed between different power sources such as wind power, solar power, hydro power and thermal power in Western China, and the problem of randomness and fluctuation of renewable energy can also be addressed. The simulation system of the western sending terminal DC grid is set up based on the studies of the steady-state model, transient model and coordinated control strategy. Furthermore, the steady-state operation characteristics and transient operation characteristics of the western sending terminal DC grid are analyzed, as well as the impact of large renewable energy generation fluctuation on the operation of DC grid. The results show that, in view of the power change of the renewable energy converter stations caused by AC/DC fault and power fluctuation due to the weather reasons, power generation can be coordinated among the converter stations to achieve emergency backup of all kinds of energy sources and reduce the disturbance impact. Therefore, the western sending terminal DC grid can realize the stable long-distance transmission of large-scale renewable energy.

Optimal Planning of Terminal Locations and Capacity of UHVDC Considering Constraints of Receiving-End Power Grid Support Capability

YU Linlin, YAN Ge, YAN Xintong, MAO Yubin, CHEN Shuyu, LI Tiantian, WEN Yunfeng

2023, 56(8): 175-185. DOI: 10.11930/j.issn.1004-9649.202303052

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Ultra-high voltage direct current (UHVDC) transmission has the high capacity to transmit power over a long distance, which has effectively alleviated the problem of mismatch between the load's demand and the clean energy distribution in China. However, with the increasing number and capacity of UHVDC infeed in the receiving-end power grid, the supporting capacity of the receiving-end power grid decreases significantly, and the safety and stability risks of the power grid rise sharply. Therefore, this paper puts forward a optimal planning method for terminal locations and capacities of UHVDC considering the constraints of the grid support capacity. Firstly, considering the voltage and frequency support capability of the receiving-end power grid, a coordinated planning model of UHVDC terminal locations (including the DC terminal locations, access mode selection and near-region grid optimization) is constructed, which transforms the DC terminal location planning problem into a mathematical optimization problem. Furthermore, the model is decomposed into a upper layer for planning and a lower layer for operation checking, and the the Benders decomposition algorithm is used to realized the iterative solution of the complex optimization model. Finally, a case study is made on an improved IEEE-39 node system and a provincial power grid. The results of calculation and simulation show that compared with the comparison schemes, the planning scheme for DC terminal locations determined by the proposed model can improve the voltage and frequency stability against the AC and DC faults of the receiving-end power grid to a certain extent.

Assessment of New Energy Supportability of Distribution Network Considering Demand Side Management and Network Reconfiguration

LIU Guowei, MA Nan, DENG Hao, CHENG Zhuo, CAO Yi, LIU Zhiwen

2023, 56(8): 186-192. DOI: 10.11930/j.issn.1004-9649.202209096

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A new energy supportability assessment method of distribution network considering demand-side management and network reconfiguration is proposed. Firstly, a demand-side management and network reconfiguration model suitable for new energy carrying capacity assessment of distribution network is constructed. Secondly, with the goal of maximizing the supportability of distributed new energy, a new energy supportability assessment model of distribution network considering demand-side management and network reconfiguration is established. And then, the model is solved using second-order cone relaxation method. Finally, an improved IEEE 33-bus distribution network is used for simulation, and a comparative analysis of the new energy supportability of the system distribution under different scenarios is carried out. The results show that considering the demand-side management and network reconfiguration can effectively improve the distributed new energy supportability of distribution network.

Restraint Scheme of Transformer Zero Sequence Differential Protection Based on Tanimoto Similarity

ZHU Jia, WANG Feng, LI Yiquan, JIAO Shaolin, XU Xiaochun, ZHAO Qingchun

2023, 56(8): 193-199. DOI: 10.11930/j.issn.1004-9649.202302076

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As one of the important transformer protections, zero sequence differential protection has the advantages of high sensitivity and strong anti-interference ability. The comparison object of its protection criterion is the self-generated zero sequence current and neutral zero sequence current obtained by the sum of three phase currents on the side of the three-phase incoming line. The difference of saturation characteristics between the three phase incoming-line side CT and the neutral side NCT will cause errors of zero sequence current transmission. The zero sequence current waveform after CT transmission will produce distortion in different degrees, which leads to the generation of false differential current, and then causes the misoperation of zero sequence differential protection. To solve this problem, on the basis of an analysis of the magnitude and phase characteristics of zero sequence current on both sides after CT transmission under various working conditions, a Tanimoto similarity-based constraint scheme for transformer zero-sequence differential protection is proposed, and the effectiveness of the proposed constraint scheme is verified by simulation.

Suppression Strategy of Unintentional Emission Supraharmonic Based on Edge Computing for Wind Farms

LI Tianchu, RONG Bin, WU Zhipeng, HUANG Jue, HUANG Kailai, YANG Gang, YI Yang

2023, 56(8): 200-206,215. DOI: 10.11930/j.issn.1004-9649.202208056

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To solve the unintentional emission supraharmonic problem at the grid-connected point of wind farm group, this paper introduces a supraharmonic suppression mechanism and a carrier phase optimization control strategy based on edge computing. Firstly, a supraharmonic emission model is established for the grid-side converter of wind generators and the propagation characteristics of supraharmonic is analyzed with consideration of the Bergeron distribution parameter model. And then, considering the influence of active power, carrier phase, and other parameters of wind generators, the quantitative relationship between the carrier phase and the supraharmonic phase is studied. A phase adjustment model of unintentional emission supraharmonic is constructed for grid-connected wind power systems, and a supraharmonic suppression method is proposed through controlling supraharmonic phase. Finally, taking advantage of the low-latency advantage of the edge computing in data calculation, the optimal control algorithm for the carrier phase of the wind farm group is deployed on the wind generator side, and the unintentional emission supraharmonic suppression strategy is proposed for wind farm group based on edge computing. The simulation results show that the supraharmonic suppression mechanism and control strategy can significantly eliminate supraharmonic at the grid-connected point of wind farm group.

Fault Location Method for Communication Link with Multi-information Fusion Modeling of Smart Substation

PI Zhiyong, ZHU Yi, LIAO Xuan, LI Zhenxing, FANG Hao, WU Pei

2023, 56(8): 207-215. DOI: 10.11930/j.issn.1004-9649.202212075

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In order to solve such problems of smart substations as numerous alarm information caused by communication link failure and poor operation efficiency, a fault location method for communication link is proposed with multi-information fusion modeling of smart substation. Firstly, a communication network numbering principle is proposed by traversing the device nodes of SCD. Secondly, by fusing multiple alarm information, the node and link coding rules are formulated, and the node-link mapping relationship and positioning model are established. And then, the adaptive genetic particle swarm algorithm is used to solve the positioning model to achieve accurate positioning of link faults. Finally, taking the secondary network of a 220 kV smart substation as an example, the effectiveness of the proposed method is verified under different link failure scenarios.

Review and Prospect of Power Standard Digitization for Machine Readable Standards

MA Chao

2023, 56(8): 216-229. DOI: 10.11930/j.issn.1004-9649.202302021

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In the context of electric power digital transformation, it is urgent to carry out research on the digital transformation of electric power standards in order to give full play to the fundamental, leading, strategic, normative, and supportive roles of electric power standards in the process of digital transformation, and thereby promote the work of electric power standardization to be more convenient, efficient, and intelligent. Therefore, it is of great significance to study the electric power standard digitization for machine readable standards. Currently, there is no consensus on the development needs, core issues, technical paths, and application scenarios of the digital transformation of electric power standards, which is still in the exploration stage. In this context, the paper firstly reviews the relevant concepts of standard digitization and summarizes the common issues in the current transformation and development of standard digitization in China. Secondly, two issues that need to be considered in the digital transformation of electric power standards are analyzed in depth from the perspectives of the differences between electric power and other industries, and the characteristics of the electric power industry itself. And then, the overall technical path for the digital transformation of electric power standards is constructed from three dimensions of overall thinking, core technologies and typical cases. At the same time, four business scenarios for electric power standard digitization are constructed, including "analysis and display of power standard contents, comparison of power standard indicators, digitization of power UAV inspection standards, and digitization of power supply chain standards". Finally, suggestions are proposed for the development of digital transformation of electric power standards, and prospects for the development of digital transformation of electric power standards in the future are presented, with a view to providing decision-making references for the development path of digital transformation of electric power standards in the future.

Research on Operation Optimization of Energy Cascade Utilization Heating Based on Exergy Analysis

HOU Jianjun, FU Xiliang, LI Ransheng, LIU Guixi, SUN Yanping, SUN Li, LIANG Zhanwei

2023, 56(8): 230-240. DOI: 10.11930/j.issn.1004-9649.202304078

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In order to realize the optimization of energy cascade heating unit, An analysis-based evaluation model of heating economy is established, Got the whole plant efficiency, the heating index, And power generation coal consumption and heating coal consumption based on analysis; The simulation model built based on the thermal system integration and optimization software, This paper studies the operation economy of high back pressure heating unit, high and low side steam extraction-back pressure heating, middle exhaust steam heating and middle exhaust steam extraction-back pressure heating, The results show that the best efficiency, index, power generation coal consumption and heating coal consumption index of middle exhaust steam-back compressor are better than other heating modes; Based on the analysis method, the heating coal consumption can be the economy of different energy heating modes. The research results provide support for the operation optimization of energy cascade using heating transformer condition.

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