Table of Content

28 August 2025, Volume 58 Issue 8

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Flexible Resource Planning Operation and Dynamic Control of AC/DC Power Distribution System

Optimal Dispatching Method of Demand-Side Resources with Load Aggregator Participation

FU Chengcheng, ZHANG Chunyan, LIU Jianye, JIA Dexiang, LI Dan, WANG Su

2025, 58(8):  1-11.  DOI: 10.11930/j.issn.1004-9649.202407085

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Demand response (DR) technology is an important means to realize new energy consumption and dual-carbon strategy. However, independent demand-side entities lack effective participation pathways in dispatch due to the decentralized characteristics of demand-side resources (DSRs) and limited actual dispatch capacities. For this reason, an optimal dispatch methodology for DSRs with load aggregator participation is proposed, with consideration of multi-operator consensus, multi-category DR and carbon emissions. Firstly, the basic management mode of DSRs was analyzed. Secondly, an optimal dispatch model for DSRs was established by integrating the economic cost and carbon emission objectives with consideration of carbon emissions and multi-category DR. Finally, the sparrow algorithm was used for simulation to verify the effectiveness of the optimal dispatch model. The simulation results show that the proposed model can effectively reduce the energy use cost of decentralized resources by 5%, significantly improve the economic cost and carbon emissions of DSRs entities, and enhance the DSRs management level, which provides an effective means for the optimal dispatch of low-carbon resilient power grid.

Single-Pole High-Resistance Grounding Protection for DC Distribution Lines Based on Current Integral Quantity Correlation

JI Xingquan, MAO Huizong, YE Pingfeng, LIU Zhiqiang, ZHANG Xiangxing, HUANG Xinyue, NI Yachao

2025, 58(8):  12-22, 30.  DOI: 10.11930/j.issn.1004-9649.202408060

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When a single-pole high-resistance grounding fault occurs in a DC distribution system, the transient current amplitude is small and the fault characteristics are weak, making it hard for the existing protection methods to provide reliable protection for the DC system. Therefore, a single-pole grounding protection method is proposed for the DC distribution lines based on current integral quantity correlation. According to the transient current characteristics of the high-resistance grounding faults, distinct polarity difference features of fault currents are identified between internal and external faults. The current integral sequence is calculated to highlight the overall change situation of the current. Pearson correlation analysis is employed to quantify the current correlation degree between the line terminals. Based on the correlation level, a fault detection criterion is constructed to achieve protection against single-pole grounding faults in DC distribution lines. Based on PSCAD/EMTDC simulation platform, the simulation results show that the proposed method can provide accurate fault protection under relatively weak fault features, with high protection sensitivity and reliability.

Intelligent Control Strategy for PEDF Accessed in Distribution System Driven by Brain Emotion Learning

CHEN Weidong, SUN Leping, WU Xiaorui, WU Ning, GUO Min

2025, 58(8):  23-30.  DOI: 10.11930/j.issn.1004-9649.202412055

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Aiming at the voltage stability control problem of the low-carbon photovoltaic storage direct-flexible system connected to the distribution network in the park, a secondary control strategy based on brain emotional learning-based intelligent controller (BELBIC) is proposed in this paper. Different from the traditional control method, the controller has the ability of fast automatic learning and can handle the complexity, nonlinearity and uncertainty of the photovoltaic storage direct-flexible system model. The proposed controller is completely model-free and maintains robust regulation capability when the system model and parameters are unknown. The method ensures low steady-state variation and high bandwidth, and ensures stable voltage control and accurate current sharing of the converter under the droop mechanism. Finally, real-time simulation is carried out on the OPAL-RT simulator to verify the robustness of the proposed control strategy under different conditions. The results show that the strategy can realize bus voltage recovery and load current accurate proportional distribution within the allowable range of communication delay, and has outstanding plug-and-play capabilities, providing an innovative solution for the flexible access of high-proportion distributed energy in new distribution systems.

Panoramic Optimal Prediction of Load 8760 Curve Guided by Gaussian Distribution

LUO Chao, NI Tian, CHEN Lingyun, KANG Yi, HOU Hui, WU Xixiu

2025, 58(8):  31-40.  DOI: 10.11930/j.issn.1004-9649.202411079

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Accurate long-term load forecasting provides base data for power system planning. However, most of the existing long-term load forecasting adopt the form of long time scale such as year and month, without considering the randomness and volatility of load. Taking the power load as variables, a panoramic optimization prediction method of 8760 load curve guided by Gaussian distribution is proposed. Firstly, a long-term panoramic load forecasting framework of load 8760 curve is proposed, which describes the long-term load changes in a panoramic and refined structure for a year which consist of 8760 h. The multi-time scale load indicators contained in the curve were analyzed and decomposed into long-term trend, medium-term fluctuation and short-term change according to statistical characteristics. The probability distribution of the maximum daily load with high fluctuation is determined by Gaussian hypothesis test. For other indicators with obvious statistical characteristics, the change rule is found on its time scale. Then, the load probability optimization model is established with the maximum load probability as the objective function, and the panoramic load prediction is transformed into an optimization problem. By predicting the load characteristics of different time scales, the constraints of the model are formed, and the optimization model is solved and the target annual load 8760 curve is restored. The results of the actual load data arithmetic examples in the central and southern provinces of China show that the proposed method accurately describes the panoramic loads in the form of load 8760 curves by determining the load probability distributions, which can effectively improve the accuracy of long-term forecasting and has great generalizability and interpretability.

Differentiated Governance Strategies for Distribution Transformer Overload and Three-Phase Imbalance Considering Source-Load Regulation

YANG Qiang, LUO Yingting, SHI Mo, JIANG Junfei, RUAN Dihang, LIU Shengyang, YAN Qin, MA Rui

2025, 58(8):  41-49.  DOI: 10.11930/j.issn.1004-9649.202501016

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Aiming at the mixed problems of three-phase imbalance and heavy overload of distribution transformers caused by large-scale access of single-phase distributed photovoltaic and single-phase charging piles, a differentiated governance strategy for heavy overload and three-phase imbalance of distribution transformers considering source-load regulation is proposed. Firstly, a substation imbalance and heavy overload model considering the randomness of photovoltaic charging is established, and the influence of the uncertainty of photovoltaic output and charging behavior on the three-phase imbalance and heavy overload of the substation is analyzed. Secondly, a substation evaluation and clustering model considering the potential of source-load regulation is established, and the substations with the potential of source-load regulation are mined as control clusters; finally, a substation regulation model considering three-phase imbalance and heavy overload is established, with three-phase imbalance, load rate and network loss as the objective function, considering the coordinated control of aggregated photovoltaic control, aggregated charging power control, energy storage and reactive power compensation, and solving it by NSGA-Ⅱ algorithm and maximum fuzzy satisfaction method. The IEEE33 node example model is used for simulation verification, and the results show that this method can effectively manage the mixed problems of three-phase imbalance and heavy overload in the substation.

Synergistic Optimization of Harmonic Suppression and Loss Reduction in Distribution Networks Based on PSO

LI Zhipeng, LIU Shaobo, YANG Hao, DONG Rui, QI Chenfeng, SHEN Shuo, ZHAO Peng

2025, 58(8):  50-59.  DOI: 10.11930/j.issn.1004-9649.202503008

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With the increasing complexity of distribution networks and the growing demand for power quality, harmonic pollution and network losses have become key factors affecting system stability and operational efficiency. This paper proposes an innovative approach based on the particle swarm optimization (PSO) algorithm, aimed at simultaneously optimizing the configuration of capacitors and active power filter (APF) to achieve the dual objectives of harmonic suppression and network loss minimization. First, a harmonic power flow analysis model is used to assess harmonics, with frequency-domain modeling based on the harmonic penetration method. Then, the simultaneous configuration of capacitors and APF in the distorted distribution network is modeled, and the mixed-integer nonlinear programming problem of optimizing the simultaneous configuration of capacitors and APF is solved using the PSO algorithm. Experimental results show that proper configuration of capacitors and APF significantly improves the network's voltage quality, the proposed synergistic optimization method not only reduces system costs but also significantly improves the network's power quality and operational efficiency.

Energy Management Strategy for Distributed Energy Systems Considering the Regulation Capability from Flexible Loads

GUO Qi, CHEN Mengxiao, YU Jiawei, HUANG Yiheng, GUO Haiping

2025, 58(8):  60-68.  DOI: 10.11930/j.issn.1004-9649.202411005

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The impact of climate change, electricity price fluctuations, and electricity consumption behavior on the flexible regulation boundaries of the load side constrains the economic efficiency of day-ahead energy management strategies in distributed energy systems. To address this issue, a two-stage stochastic optimization method based on the potential for flexible load regulation is proposed. In the first stage, the objective is to minimize the comprehensive operating costs of the distributed energy system, encompassing equipment maintenance, energy procurement, carbon emissions, and compensation costs for flexible electric and thermal loads. The second stage incorporates a compensation mechanism to mitigate deviations in renewable energy output and flexible load regulation boundaries, formulating a dynamic optimization model that accounts for intraday reserve costs. Case study results demonstrate that the proposed method effectively reduces total system operating costs and enhances renewable energy utilization. Further sensitivity analysis indicates that, compared to adjustable electric load uncertainty, adjustable thermal load uncertainty exerts a more pronounced impact on system operation.

Research on Low-carbon Operation Strategies for Regional Integrated Energy Systems Based on Multi-agent Three-level Game

WANG Hui, XIA Yuqi, LI Xin, DONG Yucheng, ZHOU Zilan

2025, 58(8):  69-83.  DOI: 10.11930/j.issn.1004-9649.202411078

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To address the conflicts of interests among multiple stakeholders in regional integrated energy systems, as well as the issues such as high investment costs, uneven capacity utilization, and significant carbon emissions associated with user-side distributed energy storage, we proposed a low-carbon operation strategy for regional integrated energy systems based on three-level game among cloud energy storage service providers, integrated energy system operator (IESO), and load aggregators (LA). Firstly, an energy trading framework was established between the IESO and LA for leasing cloud energy storage. Secondly, considering the profit maximization demands of multiple rational stakeholders, a three-layer game model for the integrated energy system was established. The first layer is a principal-agent game with IESO as the leader and LA alliance as the follower; the second layer is a master-slave game with cloud energy storage service provider as the supplier and IESO as the receiver; the third layer is a cooperative game among LA alliance members, and the revenue is distributed using the asymmetric Nash bargaining method. Finally, the model was solved using the bisection method, KKT conditions, and the alternating direction multiplier method (ADMM). The simulation results show that the proposed strategy not only promotes the system's low-carbon operation, but also satisfies the economic needs of all stakeholders.

New Energy and Energy Storage

Adaptability Analysis of Positive Sequence Fault Component Direction Element Under the Condition of Electrochemical Energy Storage System

CHEN Rui, ZHENG Tao, REN Xiang, SHEN Wentao, ZHANG Lu, QIANG Yuze, LIU Bo, WANG Yuxuan

2025, 58(8):  84-93, 138.  DOI: 10.11930/j.issn.1004-9649.202503049

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When a fault occurs in the outgoing line of a large-scale battery energy storage system (BESS), the positive-sequence fault component impedance characteristics differ significantly from traditional power sources due to the influence of its low voltage ride-through (LVRT) control strategy. Based on BESS-related technical specifications, this paper categorizes the operational mode transition methods into three types according to BESS charging/discharging modes before and after faults. Furthermore, taking into account the LVRT control strategy of BESS, we derive expressions of the positive-sequence fault component impedance angle under different operational mode transitions, thereby analyzing the impacts of various influencing factors on the impedance angle. Accordingly, the adaptability of positive-sequence fault component directional elements in BESS-integrated scenarios is investigated. Finally, the correctness of theoretical analysis is verified using the Matlab/Simulink simulation platform.

Fault Identification for Wind Turbine Based on Attention Mechanism and RCN-BiLSTM Fusion

CHEN Xiaoqian, YIN Liang, ZHAN Zonghui, WANG Fang, LI Xutao

2025, 58(8):  94-102.  DOI: 10.11930/j.issn.1004-9649.202412081

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To improve the identification accuracy of wind turbine faults, an RCN-BiLSTM-Attention wind turbine fault identification method based on the attention mechanism (AM) and the fusion of residual capsule network (RCN) and bidirectional long short-term memory (BiLSTM) network is proposed. First, the abnormal values in the wind turbine supervisory control and data acquisition (SCADA) system are eliminated by the density-based spatial clustering of applications with noise (DBSCAN) algorithm. Then, RCN is employed to extract spatial relational features from the fault data, the BiLSTM is performed to dynamically capture the hierarchical temporal dependencies of the spatial features extracted by RCN to obtain the temporal information of multiple faults, and fusion AM assigns different weights to the outputs of BiLSTM to enhance the accuracy of wind turbine fault identification. Finally, the SCADA data of several wind turbines are used to verify that the proposed model provides high identification accuracy and generalization ability compared with other models.

Coordination Optimization Method for New Energy Distribution Network Based on Reversible Pumped Hydro-Storage

CHEN Feng, ZHAO Peng

2025, 58(8):  103-108.  DOI: 10.11930/j.issn.1004-9649.202412057

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At present, the share of new energy in the distribution network is increasing, and its inherent intermittency and volatility pose severe challenges to the management of the distribution network. To this end, a new energy distribution network coordinated optimization method based on reversible pumped hydro-storage (RPHS) is proposed, and an energy management system based on RPHS is constructed to minimize the levelized cost of energy (LCOE), and the coordinated optimization configuration of new energy is realized. The proposed method is verified through the design of simulation experiments. The results show that RPHS has achieved remarkable results in improving energy utilization efficiency, reducing operation costs, and system stability.

New-Type Power Grid

Synergistic Effect of Green Certificate-Carbon-CCER Market Trading Subjects

CHEN Yongquan, YANG Wanjia, WANG Mengyu, LI Jialin

2025, 58(8):  109-117.  DOI: 10.11930/j.issn.1004-9649.202410082

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In order to realize the goal of “double carbon”, we study the synergistic effect of thermal power generators in the green certificate market, carbon market and Chinese certified emission reduction (CCER) market under the background of market expansion. We construct a trading framework for thermal power generators under the multi-market association, and analyze the synergistic effect of emission control enterprises and emission reduction impacts under the market expansion based on the multi-subject non-cooperative game model, and adopt the empirical mode decomposition (EMD) combined with the support vector machine (SVM) model to predict the carbon emission right trading volume, and to estimate the carbon emission right trading volume, and to estimate the carbon emission right trading volume. Empirical mode decomposition (EMD) combined with support vector machine (SVM) model is used to predict the volume of carbon emissions trading and provide key parameter support for the game model. The results show that the thermal power industry dominates the market through flexible strategies, while the steel and cement industries rely more on carbon emissions trading and CCER compliance, and there are differences in the performance of different industries in the market, and the expansion of the carbon market, and the combination of green certificates and CCER effectively alleviate the pressure of the carbon market.

Bi-level Optimization Peak-shaving Strategy for Short-process Steel Enterprises Considering Maximum Demand Based on an Improved RTN Model

LIU hang, SHEN hao, JI Ling, ZHONG Yongjie, CHEN Jiarui, YU Yang

2025, 58(8):  118-129.  DOI: 10.11930/j.issn.1004-9649.202503038

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As large energy users, the short-process steel enterprises have great potential for peak-shaving, which provides an important resource for improving the peak-shaving state of the power grid. However, their production processes are closely linked and orders fluctuate greatly, resulting in irregular electricity consumption, which makes it difficult for steel enterprises to participate in power grid peak-shaving. To this end, this paper proposes a bi-level optimization peak-shaving strategy for short-process steel enterprises considering maximum demand based on the improved resource-task network (RTN) model, so as to help short-process steel enterprises participate in power grid peak shaving. Firstly, an improved RTN with time window nodes was designed to accurately characterize the coupling relationships of materials and temporal resources between devices within a single production line when processing different types of orders, ensuring the feasibility of order allocation and scheduling strategies. Secondly, enterprise orders were allocated based on the actual multi-production-line scenarios, and a supply-demand interaction bi-level optimization peak-shaving model considering maximum demand was proposed, which was solved using a hybrid algorithm combining adaptive particle swarm optimization (APSO) and the Cplex solver. Finally, according to the data from an actual short-process steel enterprise, three simulation scenarios were set up to verify the proposed scheduling strategy. The results show that the proposed strategy can effectively smooth the load curve while reducing the enterprise’s electricity costs.

Stochastic Optimization Strategy for Load Management of Industrial Park Under Energy Constraints

RU Chuanhong, LU Ji, QIN Jian, ZHANG Junda, CHANG Junxiao, JIANG Beini

2025, 58(8):  130-138.  DOI: 10.11930/j.issn.1004-9649.202311142

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In order to solve the load management problem of industrial park microgrids in the event of energy shortage, this paper proposes a new method for managing user-specific loads. By defining the user-specific load management as a stochastic predictive model control problem, this method firstly establishes prediction models for photovoltaic and users’ power demand, and then solve them using two-stage stochastic programming and approximate dynamic programming. Finally, the effectiveness of the alternative solutions is tested through two controllers in an environment in which user response to the load management is simulated. The results indicate that even if the controller does not have a complete model of user response, the predictive models used for scheduling the load management can significantly improve the power availability and user consumption efficiency.

Transient Stability Assessment Method for Multi-machine Power Systems Considering Dense Channels

WANG Xuejun, FANG Shuiping, CHI Guangyong

2025, 58(8):  139-146.  DOI: 10.11930/j.issn.1004-9649.202501042

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To improve the accuracy and efficiency of power system transient stability assessment, a transient stability assessment method for multi-machine power system considering dense channel based on deep transfer is proposed. Firstly, a new transient stability index is proposed, and a data set and fluctuation equation of power system considering dense channel are established. Secondly, a deep transfer learning method for transient stability assessment using a pre-trained deep convolutional neural network is proposed. Finally, the effectiveness and efficiency of the proposed method are verified by simulation.

Reliability Improvement Strategy for Transformer Zero-Sequence Differential Protection Based on Zero-Sequence Current Amplitude Difference Characteristics

ZHENG Junchao, GE Yaming, KONG Xiangping, REN Xuchao, CHEN Shi, WANG Chenqing

2025, 58(8):  147-155.  DOI: 10.11930/j.issn.1004-9649.202409080

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The zero-sequence differential protection of transformer may cause the reliability to decrease or even malfunction due to the fault of current transformer (CT) when dealing with complex inrush current and fault. To solve this problem, a strategy to improve the reliability of transformer zero difference protection is proposed. The zero-sequence current and its amplitude characteristic are analyzed and studied to obtain the relevant auxiliary criterion and the simulation model is established to simulate the typical working conditions such as zone fault, outside fault and complex inrush current. The simulation results show that the auxiliary criterion can effectively improve the reliability of zero-sequence differential protection and avoid the malfunction caused by the deterioration of the transmission characteristics of current transformer.

Data Driven Analysis and Control of Power System Security and Stability

ZHANG Dingqu, QIAN Bin, YANG Lu, CHEN Feng, LUO Yi

2025, 58(8):  156-163.  DOI: 10.11930/j.issn.1004-9649.202410010

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In order to control the transient over-voltage accurately and deal with the sharp change of voltage in time and effectively, this paper proposes a data-driven power system security and stability analysis and control strategy under the condition of high proportion of photovoltaic power generation connected to the grid. This strategy involves continuous monitoring of key electrical indicators such as voltage fluctuations in the high-penetration PV grid-connected system, upon which a neural network model based on Radial Basis Function-Particle Swarm Optimization (RBF-PSO) is constructed. Using real-time data, the model can predict the transient behavior of the power grid. Once the prediction indicates a risk of transient over-voltage, the system immediately sets the nodes to be controlled according to preset priorities and, in combination with sensitivity analysis at PV connection points, automatically activates the preset transient over-voltage control mechanism by adjusting the reactive power compensation and active power reduction functions of the PV inverters. This aims to swiftly restore system voltage stability and ensure equipment safety. Experimental verification shows that this method not only responds rapidly but also significantly reduces the reactive power required by PV inverters.

Grid-Forming Technologies

A New Pilot Protection for Transmission Lines Based on Overcurrent Limiting from Grid-Forming Power Sources

MA Bingqing, LI Zhenxing

2025, 58(8):  164-175.  DOI: 10.11930/j.issn.1004-9649.202501046

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Grid-forming renewable energy sources have attracted widespread attention due to their excellent damping and inertia support characteristics. However, their complex fault response characteristics lead to compromised effectiveness of conventional protection schemes. To address this issue, this paper proposes a novel differential protection scheme combining fault current limiting and waveform similarity. First, based on an analytical model of fault current in grid-forming sources, the failure mechanism of traditional protection is revealed. Further considering inverter current tolerance and grid code requirements, an adaptive virtual impedance calculation module is designed to form an auxiliary control strategy for grid-forming sources, effectively suppressing inverter overcurrent during system short circuits. Finally, based on waveform similarity theory, cosine similarity is employed to quantify current waveforms at both ends of transmission lines. By analyzing significant differences in similarity between internal and external faults, a new differential protection criterion is established. A simulation model built in PSCAD/EMTDC verifies the proposed scheme under various fault scenarios. Results demonstrate that the scheme achieves simultaneous short-circuit current suppression and accurate fault zone identification, maintaining high reliability, sensitivity, and rapidness even under high-resistance grounding conditions.

Adaptability Analysis of Transmission Line Protection under the Control Strategy of Grid-Forming Energy Storage Converter

FENG Xiaoping, CHEN Qidi, ZHAO Qingchun, WANG Xing, LI Bin, XIE Hua

2025, 58(8):  176-184.  DOI: 10.11930/j.issn.1004-9649.202410090

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Under the dual carbon target, a large number of new energy sources are connected to the power grid, and relay protection is becoming increasingly important as the primary guarantee for the safe and stable operation of the power system. The research on grid type inverter technology mainly focuses on system stability control, fault ride through, and other aspects, with little attention paid to the characteristics of relay protection. In this regard, this article analyzes the adaptability of transmission line protection under the control strategy of grid type energy storage inverters. Firstly, the synchronous control strategy and fault ride-through control strategy of grid-forming converters are analyzed, with equivalent circuits derived for grid-forming converters under different fault ride-through control strategies in the event of faults. Secondly, an evaluation of the operational performance under grid-forming control strategies is conducted. Additionally, an adaptability analysis is performed for each of these protection configurations. Lastly, a transmission line model incorporating a grid-forming energy storage converter is established in Simulink to validate the relevant theories. Based on the adaptability of transmission line protection, corresponding improvement suggestions are proposed.

Longitudinal Protection of Grid-Forming New Energy Outgoing Lines Based on Composite Sequence Current Characteristics

YUAN Song, GE Zhao, Tang Jiajie, MEI Jiabao

2025, 58(8):  185-192.  DOI: 10.11930/j.issn.1004-9649.202410068

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The access of grid-forming new energy centralized transmission system has significantly changed the fault characteristics of the grid, and the traditional longitudinal protection is prone to sensitivity reduction or even refusal risk when the transmission line fault occurs. Based on this, this paper proposes a new principle of longitudinal protection for transmission lines of grid-forming new energy units based on composite sequence currents. Considering the limiting effect of the grid-forming new energy unit's inherent control strategy on the positive-sequence component and the negative-sequence component during faults, the faults of grid-forming new energy transmission line are classified into symmetrical faults, asymmetrical faults, and centralized transmission faults. The positive sequence component and negative sequence component are used to construct the protection criteria, and the positive sequence mutation is proposed to construct the protection criteria for the centralized transmission fault scenario. On this basis, the three fault characteristics are integrated and the protection criterion based on compound sequence current is constructed to further improve the sensitivity and rapidity of protection. The performance of the proposed new protection principle is verified by constructing a model of new energy centralized transmission system in PSCAD. The simulation results show that it still has high sensitivity even in the case of high resistance grounding.