Electric Power

Study on the Influence of Electric Vehicle Development and the Vehicle-Grid Interaction on New Energy Storage Configuration in China

Yuanbing ZHOU, Naiwei GONG, Haojie WANG, Jinyu XIAO, Yun ZHANG

2024, 57(10): 1-11. DOI: 10.11930/j.issn.1004-9649.202405058

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With the continuous and rapid development of electric vehicles, the positive interaction between electric vehicles and the power grid in the future will affect the new energy storage configuration of the power system. In view of the insufficient overall planning of the current new energy storage, resulting in high development expectations, this paper proposes that new energy storage and the development of electric vehicles must be considered as a whole, and pay attention to the replacement of vehicle-grid interaction for short-term new energy storage. The key factors affecting the development of electric vehicles and the adjustment ability of the vehicle-grid interaction are analyzed. Based on the development of electric vehicles in China, combined with the energy consumption habits of electric vehicles and the system adjustment demand, the interaction model of the electric vehicles and the system in China is constructed. The flexible adjustment ability of electric vehicles is evaluated, and the impact on the new energy storage configuration in China and its seven regions is analyzed.

A Distributional Robust Distribution Network Reconfiguration Method Based on Compressed Switch Candidate Set

Haocheng DU, Shilong LI, Yuntao JU, Jinqi ZHANG

2024, 57(10): 12-24, 35. DOI: 10.11930/j.issn.1004-9649.202403022

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In the large-scale multi-moment distribution network reconfiguration (DNR) problem, a large number of switches to be optimized seriously reduces the solution efficiency of distribution network reconfiguration. To address this problem, a distributional robust distribution network reconfiguration model based on a compressed switch candidate set was proposed, which was divided into two stages. The first stage took the minimization of active network loss of the system as the objective function and used the optimal matching loop flow method to compress the switch candidate set; the second stage took the minimization of the sum of the power purchase cost and the switch action cost as the objective function, constructed the chance constraints on the capacity limits of the power point, and adopted a Wasserstein ball-based distributional robust method to deal with the uncertainty of distributed generation. It transformed the model into a mixed-integer second-order conic planning problem by deterministically transforming the worst-case expectation and chance constraints in the objective function by using a dual transformation method. Finally, numerical experiments were conducted on the 33 node and Liaoning Panjin 45 node systems, which proved that the model proposed in this paper could effectively improve the computational efficiency, and the decision maker could adjust the economy and conservatism of the model by changing the number of samples and the confidence level, compared with the robust model and the stochastic planning model.

Linear Active Disturbance Rejection Control Parameter Tuning Method for Energy Storage Converter with Enhanced Stability

Shilong LI, Longjiang LI, Xinbo LIU, Hua ZHANG

2024, 57(10): 25-35. DOI: 10.11930/j.issn.1004-9649.202402009

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In order to compensate for the negative impedance characteristics of constant power load in the direct current (DC) microgrid, it is necessary to speed up the response speed of the hybrid energy storage system and give full play to its performance. This paper proposed a linear active disturbance rejection control parameter tuning method based on the mixed potential function theory for the energy storage converter of the microgrid. Firstly, the active disturbance rejection transfer function of the energy storage converter was derived. Then, the stability of the DC microgrid with a hybrid energy storage system and constant power load was analyzed, and the mixed potential function criterion considering the bandwidth ω₀ of the extended state observer was derived, which provided an important basis for tuning the linear extended state observer bandwidth and the state error feedback control parameter of the energy storage converter with active disturbance rejection control. Experimental results show that the proposed method has a fast response speed and strong disturbance rejection ability, which ensures the stable operation of the DC microgrid system.

Influence Rules and Mechanism Analysis of Distribution Network Flexibility Degree on Distributed Generator Accommodation

Haishen LIANG, Kangli WANG, Hongyu SONG, Jinna HAO, Jun XIAO

2024, 57(10): 36-45. DOI: 10.11930/j.issn.1004-9649.202311092

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Two hot topics in distribution network research are power electronics flexibility and distributed generator (DG) accommodation. This paper revealed the influence rules and their mechanisms of distribution network flexibility degree on DG accommodation. Firstly, the concept of distribution network flexibility degree was introduced, and its definition was improved. Then, by taking typical wiring modes and the expanded IEEE RBTS-Bus4 test system as the research objects, the change in the DG accommodation ratio was observed as the flexibility degree started from 0, and the rules and mechanisms were analyzed. The results show that not all distribution network flexibility can improve DG accommodation, and there is an effective condition. In other words, there is a surplus of DG relative load in the feeder on one side of the soft open point (SOP) and a DG shortage on the other side. However, the regularity between the DG accommodation ratio and flexibility degree doesn’t appear after the effective condition is met. This paper thus proposes two approaches, namely analyzing the restriction conditions of DG accommodation increase and observing SOP installation order, and finds the hidden rules: The flexibility degree and DG accommodation ratio have a positive correlation when there is available space for DG accommodation increase, without the SOP capacity restriction, or when they are in the same SOP installation order. The rules and mechanisms found in this paper provide a new theoretical basis for guiding the flexible development and DG accommodation of distribution networks.

Application of Three-Phase Linearized Power Flow and Line Loss Analysis of Distribution Network Driven by Data and Physics Fusion

Huaitian MU, Hongliang LIAN, Juan LIU, Yanqiong LI

2024, 57(10): 46-56. DOI: 10.11930/j.issn.1004-9649.202402028

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The large-scale grid connection of distributed generation introduces non-smooth local control constraints such as droop control, which easily leads to the convergence failure of the traditional power flow calculation method based on the forward and backward substitution method. Moreover, because the grid-connected distributed generation changes the power flow direction of the system, the traditional theoretical line loss calculation methods such as the equivalent resistance method and the pressure drop method are no longer applicable. In order to solve the above problems, this paper proposed a smoothing model considering on-load tap changer regulation and distributed generation droop control and constructed a fast calculation model of linearized theoretical line loss of a three-phase distribution network driven by data and physics fusion. On the basis of traditional linearization based on steady-state operation and first-order Taylor expansion linearization, the partial least squares method was used to compensate for the linearized error. Compared to pure physics-driven linearization, it still maintained high accuracy under overload conditions; compared to pure data-driven linearization, it retained branch topology information, making it suitable for scenarios with switch status changes. The proposed model compensated for linearized errors, greatly improving the convergence and calculation efficiency of the power flow model while ensuring linearized accuracy, and it could adapt to different load levels to achieve precise error compensation. Based on the actual 42-node three-phase distribution network system simulation, it was verified that the proposed model had high accuracy and could realize the robust and fast calculation of the theoretical line loss of the distribution network.

Effective Development and Management Strategy for Distributed Smart Grids Based on Collective Intelligence

Zongchao YU, Ming WEN, Xianghua LI, Xintao XIE, Hongming YANG

2024, 57(10): 57-68. DOI: 10.11930/j.issn.1004-9649.202312024

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To overcome the challenge of accurately investing in the construction strategies of distributed smart grids under different resource endowments, an efficient development and management strategy for distributed smart grids based on collective intelligence was proposed. Firstly, relying on development planning data of massive distributed smart grids, the optimal index set for the development of distributed smart grids was constructed from three aspects of operation, planning, and development by using Ward agglomerative hierarchical clustering. Secondly, the corresponding probability distribution function was fitted according to the type of each index, and the index threshold interval was determined to achieve the objective scoring of each index. Then, the precise investment evaluation system for the development of distributed smart grids based on collective intelligence was constructed, and the horizontal and vertical difference degree of indexes was used to drive the re-weighting of collective intelligence, so as to achieve the rational evaluation of distributed smart grid construction strategy. Finally, the closed-loop feedback was formed by calculating the input-to-output ratio of the development planning, and efficient development and management of distributed smart grids was achieved. The rationality of the proposed system was verified by analyzing the development planning data of 10 000 groups in a province.

Economic Dispatch Analysis of Risk Prevention and Control Based on Game Theory Equilibrium

Qixiang WANG, Zhentao HAN, Yi LIANG

2024, 57(10): 69-77. DOI: 10.11930/j.issn.1004-9649.202402032

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To evaluate the costs and benefits of each power generation and consumption entity in the power system, it is necessary to analyze the game theory equilibrium point of the economic dispatch problem. With the massive integration of renewable energy units and the gradual improvement of users' awareness of green power consumption, both the generation and consumption sides of the power system are showing new characteristics. First of all, the low marginal cost characteristics of renewable energy units, the need for risk prevention and control of system operation, and users' demand for green power will all have an impact on the mathematical form of the economic dispatch problem. At the same time, traditional analytical methods also face problems such as numerous variables and difficulty in solving nonlinear equilibrium problems. In order to solve these problems, this paper first proposes an economic dispatch mathematical model for risk prevention and control of the power system considering green power generation and consumption and then puts forward a game theory equilibrium solution algorithm based on the optimal response method. Through case analysis, the game theory equilibrium situation of the economic dispatch problem under the generation and consumption of renewable energy is evaluated, and relevant suggestions are put forward for investment planning on the power generation side of the power system.

Injection Current Distribution Characteristics Identification Based Distribution-Level Fault Line Selection

Xiaowei WANG, Yang YUE, Liang GUO, Xue WANG, Yizhao WANG, Zhihua ZHANG, Fengfeng YANG

2024, 57(10): 78-89. DOI: 10.11930/j.issn.1004-9649.202401043

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Addressing the challenges posed by the subtle characteristics of single-phase grounding faults in resonant grounding systems, which lead to decreased sensitivity and reliability in fault line selection methods reliant on these characteristics, an innovative approach for fault line selection through active injection signal identification is proposed. Initially, the distribution characteristics of the injected current, influenced by line-to-ground conductance, are derived. These characteristics then form the foundation for constructing a robust line selection criterion. Furthermore, a thorough analysis is conducted to assess the impact of the injected signal on system operation from various perspectives. This analysis leads to the selection of an optimal injection signal with suitable parameters. Notably, to enhance the method's resilience against transition resistance, a decision is made to inject a low-frequency signal. Subsequently, the zero-sequence current of each feeder line is measured after injecting the signal. A specific steady-state zero-sequence current time window is identified, and the Prony algorithm is employed to accurately discern the 25Hz current amplitude within the zero-sequence current of each line. This approach enables precise fault line selection. Extensive PSCAD simulations and on-site waveform measurements validate the effectiveness of this method. The results demonstrate its ability to accurately identify fault lines across a range of fault scenarios, while maintaining excellent resistance to transition resistance.

An Optimized Scheme for Active Distribution Network Current Speed Protection Setting Considering Tie Switch Operation

Nuo CHENG, Dacai CHEN, Xue CHEN, Xiaofei RUAN, Shuqing WEI, Zheyu HAN

2024, 57(10): 90-101. DOI: 10.11930/j.issn.1004-9649.202402026

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Active distribution grid with tie switches has a complex grid structure and undergo frequent changes in operation mode, which greatly affects the correct operation of traditional current protection that relies on static grid topology and fixed operation mode. A setting optimization scheme for instantaneous overcurrent protection is proposed, which monitors the switch status information in real-time by the terminal unit, uploads the topology correlation matrix to the master station, and combines the output characteristics of the inverter-type distributed power supply to adaptively adjust the protection settings. The scheme can effectively enhance the adaptability of the protection to the grid topology and the output fluctuation of the inverter-type power supply with low communication pressure. Simulation results show that it can effectively increase the instantaneous overcurrent protection range, reduce the impact of DG output and better adapt to grid topology changes.

Distance Protection for Outgoing Line of Photovoltaic Station Based on Superconducting Magnetic Energy Storage

Zhihui DAI, Meiyuan LIU, Shuqing WEI, Weiping ZHU, Wenzhuo WANG

2024, 57(10): 102-114. DOI: 10.11930/j.issn.1004-9649.202403054

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Affected by the control strategy of photovoltaic inverters, the photovoltaic station has weak-feedback and current-phase-controlled characteristics. As a result, the measured impedance of the distance protection on the photovoltaic side of the transmission line cannot correctly reflect the location of the fault, and the ability to withstand fault resistance variations is significantly reduced. First, the solution equations of the line short-circuit impedance are derived according to the fault component sequence network diagram of the transmission line system. At the same time, the traditional low-voltage-ride-through (LVRT) control strategy is changed based on the superconducting magnetic energy storage (SMES) connected to the DC bus of the photovoltaic station. The unknowns in the equations are eliminated by the control and protection coordination, and then the line short-circuit impedance is solved. Finally, the distance protection scheme for outgoing line of photovoltaic station based on SMES is proposed. Compared with the existing methods for deriving the line short-circuit impedance, there is no approximate calculation in the method. As a result, the accuracy of the calculation is greatly improved. In addition, compared with other control and protection coordination schemes, while ensuring the reliable operation of the distance protection, the scheme also takes into account the reactive power support for the power grid during the fault period. Instead of being weakened, the LVRT capability is even enhanced.

Co-Optimization of Inertia and Droop Control Coefficient for Grid-Forming Photovoltaic-Storage System Considering Capacity Limits

Yingjie HU, Qiang LI, Qun LI

2024, 57(10): 115-122. DOI: 10.11930/j.issn.1004-9649.202404142

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As the renewable energy's share in the power system continues to increase, the inertia level of the system gradually decreases. The effective approach to tackle frequency stability issues is to configure energy storage to enable photovoltaic (PV) power generation to provide inertia and primary frequency regulation support. Excessively small frequency support parameters cannot fully utilize the frequency regulation capabilities of the photovoltaic-storage system, while excessively large parameters may lead to power limit violations of the energy storage or converter during transient processes, posing a risk of equipment damage. To address this, an optimized configuration method for the inertia and primary frequency regulation parameters of photovoltaic-storage systems, considering capacity constraints, is proposed. Firstly, an analytical relationship between frequency deviation, frequency dead zone, primary frequency regulation coefficient, and converter output is established based on the control equations of the grid-forming photovoltaic-storage system. This relationship allows deriving the feasible boundary of the primary frequency regulation coefficient that ensures the converter and energy storage outputs do not exceed their limits. Secondly, with the constraints of the photovoltaic-storage system's capacity limits and its dynamic equations for participating in transient frequency support, an optimization model for maximizing the frequency nadir of the photovoltaic-storage system is established to determine the optimal virtual inertia coefficient. Finally, simulation analyses verify that the proposed method can fully utilize the transient frequency support capabilities of the photovoltaic-storage system under various scenarios while satisfying capacity constraints.

Virtual Inertia Parameter Feasible Region Based High-frequency Oscillation Suppression of DC Microgrid

Rui WANG, Xueshen ZHAO, Xinhui ZHANG, Ke PENG, Honglu XU, Haoyue SUN

2024, 57(10): 123-132. DOI: 10.11930/j.issn.1004-9649.202402023

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Addressing the issue of high-frequency oscillation instability in DC microgrids caused by unreasonable virtual inertia control parameters, a low-pass filter equivalent modeling approach is proposed. This approach establishes a reduced-order model of the DC microgrid and its voltage closed-loop transfer function. From the perspective of ensuring the small-signal stability of the DC microgrid, the concept of a feasible region for virtual inertia parameters is defined in the parameter space, with droop coefficients and low-pass filter control bandwidth as the primary parameters. Based on the zeros and poles obtained from the voltage closed-loop transfer function, a method for solving the feasible region of virtual inertia parameters is proposed. This feasible region provides practical guidance for the design of virtual inertia control parameters in DC microgrids. Finally, a simulation case of a DC microgrid based on a switching model is built using PLECS software. Multiple simulation results have verified the effectiveness of the reduced-order model and the feasible region of virtual inertia control parameters.

D-S Evidence Theory Based Comprehensive Identification Model for Cause of Grounding Fault in Distribution Network

Yunpeng HU, Chenggang DU, Jun QI, Rihong ZHENG, Minfu A, Hao ZHANG, Yongliang LIANG

2024, 57(10): 133-142. DOI: 10.11930/j.issn.1004-9649.202405007

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Single-phase-to-ground fault (SPGF), being the most prevalent issue in distribution networks, significantly impacts the reliability and safety of the distribution system. Accurate identification of SPGF can enhance the level of refinement in handling grounding faults in distribution networks. Firstly, a set of candidate waveform features that effectively reflect various grounding fault causes is extracted from the fault waveforms. These features are then subjected to multivariate analysis of variance (MANOVA) to assess their correlation with grounding fault causes, thereby selecting effective features for identifying the root causes. Subsequently, fault cause identification models based on Extreme Learning Machine (ELM) and Support Vector Machine (SVM) are designed respectively. These models' recognition results are fused using Dempster-Shafer (D-S) theory of evidence fusion, establishing a comprehensive identification model for grounding fault causes. Finally, the validity of the established comprehensive identification model is verified based on field data, demonstrating its superiority over any single identification model and confirming its feasibility.

Optimization of Power System Black Start partition Target Network Taking into Account the Black Start Space-Time Support Capability of New Energy Station

Ruixin WANG, Jiguang SUN, Yan LIU, Lun CHENG, Ting XU, Guanghui SUN

2024, 57(10): 143-149. DOI: 10.11930/j.issn.1004-9649.202403073

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Taking into account the spatiotemporal support capacity of new energy station black start, a target network optimization method for power system black-start zoning is proposed to improve unconventional security defense ability of the new power system. Firstly, extended black-start power source (EBSPS) is defined based on the concept of spatiotemporal support capability for black start of new energy stations. Secondly, with the optimization objectives of minimizing electrical distance within the partition and the number of interconnections between partitions, an integer linear programming model for partition target network that takes into account EBSPS is established, in which EBSPS is transformed into a constraint on the number of partitions and other constraints such as power balance, partition connectivity, and flexibility resources are considered as well. Finally, the proposed method was validated through a simulation system to aid in the decision-making process for restoring black start zones in new energy stations.

A Decision-making Optimization Method for Network Reconfiguration of Power System With New Energy Considering the Synergistic Support of Source-grid

Jian ZHOU, Nan FENG, Yiping JI, Yuyao FENG, Shuai WANG, Shaoyan LI

2024, 57(10): 150-157. DOI: 10.11930/j.issn.1004-9649.202312022

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Facing the complex and changeable international situation and the increasing number of extreme events, it is of great significance to study the system recovery scheme under the high proportion of new energy access to improve the new power system security defense system. In this context, a decision-making optimization method for grid reconfiguration of power system with new energy is proposed. Firstly, the uncertainty of new energy output is analyzed and modeled based on the kernel density method. Secondly, considering the requirements of new energy grid connection and operation on the strength of the grid, the linearized model of multiple renewable energy stations short-circuit ratio constraint is realized. On this basis, a grid reconfiguration optimization model that can coordinate new energy, energy storage, conventional units and transmission network restoration is established and a bi-level optimization strategy is proposed to improve the efficiency of model solution. The example results based on the New England 10-machine 39-bus system verify the effectiveness of the proposed method.

Distribution Network Flexibility Evaluation Method Considering Collaborative Interaction of Flexible Resources

Zhiwen LIU, Yan LI, Chong SHAO, Xinming FAN, Qinghui ZENG

2024, 57(10): 158-165. DOI: 10.11930/j.issn.1004-9649.202403021

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A distribution network flexibility evaluation method considering collaborative interaction of flexible resources is proposed. Firstly, a flexibility evaluation indicator system is constructed, which includes three aspects: collaborative regulation capacity, collaborative efficiency quality, and power grid reliability. Secondly, a Gaussian mixture model is used to construct typical operating scenarios, and the subjective and objective weights of evaluation indicators are determined using Analytic Hierarchy Process and Random Forest Model, respectively. Through a double-layer evaluation process, the evaluation indicator values for each typical scenario are calculated. Then, based on the probability of typical scenarios appearing, the comprehensive flexibility evaluation index values of each flexible resource access scheme are weighted. Finally, the feasibility and effectiveness of the proposed method are verified through the case study on a 54-bus distribution network.

Fast Calculation Method of Probabilistic Optimal Power Flow for Renewable Dominated Power Grid Based on Improved Convex Relaxation

Wei CUI, Longyue CHAI, Cong WANG, Wei WANG, Ying WANG, Lun YANG

2024, 57(10): 166-171. DOI: 10.11930/j.issn.1004-9649.202311067

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The existing probabilistic optimal power flow (POPF) studies mainly focus on the design and improvement on probabilistic calculation methods, which may be difficult to improve the computational efficiency of POPF as POPF is a nonconvex and nonlinear programming problem under uncertainty. Therefore, this paper centers on renewable-dominated AC-DC power grid and proposes a POPF model considering uncertainties associated with wind and solar power. To efficiently solve the POPF model, an improved convex relaxation is proposed to address the nonconvex and nonlinear power flow equations and reformulate the nonlinear POPF model as convex one. Furthermore, the Nataf transformation is adopted to address the correlations of non-normal distribution and then a Monte Carlo Simulation based Latin Hypercube sampling technique is developed to solve the convex POPF model. Finally, the effectiveness of the proposed improved convex relaxation based POPF method is demonstrated by a set of case results tested on the modified IEEE 39-bus, 118-bus, and 500-bus systems.

Photovoltaic Site Selection and Capacity Determination Method for New Distribution Network Considering Multidimensional Performance Evaluation

Qifang CHEN, Ruofan LI, Mingchao XIA, Di WU, Yinchi SHAO

2024, 57(10): 172-178, 207. DOI: 10.11930/j.issn.1004-9649.202311027

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This paper proposes a new distribution network photovoltaic (PV) locating and sizing method that takes into account multi-dimensional performance evaluation. First, a multi-dimensional evaluation system covering power quality, power supply capacity, and photovoltaic access effects is formed, and a combined subjective and objective assessment system is constructed. Comprehensive evaluation method of access solutions based on weight-fuzzy evaluation. Secondly, the comprehensive evaluation was organically combined with the optimized locating and sizing process to form an evaluation-selection integrated PV site selection and capacity optimization model, using the non-dominated sorting genetic algorithm-ii (NSGA-II) achieves the optimal access location and capacity acquisition under the condition of differentiated PV output throughout the year. Finally, the numerical example verification shows that the proposed method not only significantly reduces the node voltage deviation and line transmission pressure, but also has better PV access characteristics and multi-index comprehensive performance within the scope of a more comprehensive technical performance evaluation, improving the rationality of PV configuration. safety and resource efficiency, which can effectively support the development needs of new distribution networks.

Decision Analysis of Load Aggregator Considering Dynamic Behavior of Residential Users

Xianhai ZHAO, Xiaofeng LIU, Zhenya JI, Feng LI, Guobao LIU

2024, 57(10): 179-189. DOI: 10.11930/j.issn.1004-9649.202404045

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Fully tapping into the demand response potential of load aggregators is of great significance for energy conservation and emission reduction. To study the impact of resident behavior on aggregator decision-making, this paper proposes a load aggregator decision-making analysis method that considers the dynamic behavior of resident users. Firstly, considering the multiple influencing factors of resident participation in demand response, a Markov based bounded rationality decision behavior model is generated to predict user participation level. Secondly, the information gap decision theory is adopted to address the uncertainty of user participation level, and the aggregators are divided into risk investment type and risk avoidance type. Finally, by quantitatively evaluating the opportunity profits and risk losses, the aggregators with different risk preferences can select appropriate load reduction strategies based on this algorithm to ensure the maximization of expected returns. The case study results show that when the information of resident users is incomplete, the proposed method can effectively deal with the uncertainty of resident user participation in demand response, and the load aggregators can more reasonably make decisions to ensure expected returns.

A Three-Phase Power Flow Model for Low-Voltage Distribution Networks Considering Balanced Bus Phase Asymmetry and Photovoltaic Access

Yang ZHOU, Dezhi HUANG, Peidong LI, Kailin JI, Xuefeng LIU, Hong TAN

2024, 57(10): 190-198. DOI: 10.11930/j.issn.1004-9649.202408058

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Considering the diverse connection modes and complex control strategies of photovoltaic (PV) inverter power sources integrated into low-voltage distribution networks, this paper delves into the establishment of a control model for the three-phase voltages and powers of PV inverter power sources relative to the neutral point. On this foundation, the paper further proposes a comprehensive low-voltage distribution network three-phase power flow calculation model that takes into account both the asymmetry of phase angles at balanced terminals and the factors involved in the integration of PV inverter power sources. To validate the effectiveness and accuracy of this model, simulation experiments were conducted on a modified IEEE-13 node test system. The simulation results clearly demonstrate that the model constructed in this paper can accurately and efficiently calculate the three-phase power flow in low-voltage distribution networks incorporating PV inverter power sources, providing robust theoretical support and technical means for the planning and operation of low-voltage distribution networks.

Analysis and Prospect of Gap Between Electricity Consumption and Economic Growth in China in Recent Years

Xiang WANG, Xiandong TAN, Chenglong ZHANG, Qing LIU, Yifan ZHANG

2024, 57(10): 199-207. DOI: 10.11930/j.issn.1004-9649.202405136

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From 2020 to 2023, electricity consumption in China was higher than the economic growth, causing widespread concern and doubts in society. By building an analytical model for the gap between electricity consumption and economic growth that reflected the statistical difference between industries and residents' lives, the reasons why electricity consumption was higher than economic growth were analyzed comprehensively. It was found that from 2020 to 2023, electricity consumption continued to be higher than economic growth, mainly due to the impact of electrification, digitalization, and intelligence. In addition, electricity consumption in the secondary industry was higher than the growth rate of its added value. High energy consumption sectors in the manufacturing industry had the greatest impact, while the impact of equipment manufacturing, such as electrical machinery and equipment manufacturing, computer/communications, and other electronic equipment manufacturing, was intensifying. The influence of temperature in 2022 was more prominent. It was generally expected that China's electricity consumption would still be higher than economic growth before 2030, or in other words, the elasticity coefficient of electricity consumption would still be greater than 1.

Performance Analysis of New Main Protection Scheme for Rotor Winding of Variable Speed Pumped Storage Units

Jianing BAI, Lin GUI, Miao LIU, Yanjun LI, Chenguang GAO, Tianzhi CAO, Yian YAN

2024, 57(10): 208-217. DOI: 10.11930/j.issn.1004-9649.202402020

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The operation of Fengning variable speed pumped storage units has made the main protection scheme of the rotor winding a hot issue. The multi-loop analysis method is used to simulate all possible internal faults in the rotor winding of the 12 kW AC excitation dynamic simulation electrical machine manufactured by Xiangtan Electrical Manufacturing Factory. Based on this, the performance of a new main protection scheme for the rotor winding based on stator branch harmonic circulation is analyzed, and the types of faults that the main protection scheme for the new rotor winding cannot operate are further clarified and corresponding improvement measures are proposed, which can provide a reference for the stable operation of the variable speed pumped storage units in the future domestic demonstration projects in China.

A Fault Diagnosis Method for Interturn Short Circuit of Dry-Type Air-Core Reactor Based on High Frequency Impedance Spectrum

Heqian LIU, Jian ZHANG, Haiyue ZHANG, Hongda YANG, Shiyu CHEN, Yubo SHEN, Lei WANG

2024, 57(10): 218-224. DOI: 10.11930/j.issn.1004-9649.202309025

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A detection method for interturn short circuit fault in dry-type air-core reactor is proposed using broadband impedance spectroscopy. Firstly, an equivalent distributed circuit model of intact reactor under high frequency is constructed based on the theory of multi-conductor transmission lines, and an equivalent simulation model is established based on the parameter calculation equation of the distributed equivalent circuit to analyze the high-frequency characteristics of the reactor broadband impedance spectrum. Secondly, the amplitude spectrum and phase spectrum of the broadband impedance of the reactor with interturn short circuit fault are simulated to analyze the influence of inductance parameters on the resonant frequency of the reactor impedance spectrum. Finally, an experimental testing was conducted on a small dry-type air-core reactor in the laboratory, which has verified the effectiveness of the proposed method.

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