31 August 2024, Volume 44 Issue 4

    

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  Overview of New Information Transmission Methods in Power Systems 

  LIU Jungi, WANG Rui, CAO Junwei

  Journal of Northeast Electric Power University. 2024, 44(4): 1-8. https://doi.org/10.19718/j.issn.1005-2992.2024-04-0001-09

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   Compared to power systems that use traditional RS485/CAN buses as transmission methods, the new power system has put forward new requirements for the radiation, efficiency, and power of information transmission methods Therefore, the article first introduces common information transmission methods, then elaborates on the principle of information power composite modulation from the essence of power electronics, analyzes the advantages and disadvantages of common digital modulation methods, and finally summarizes the current urgent problems and development prospects. The application of information composite modulation technology is quite extensive. When combined with the current flexible, efficient, and environmentally friendly distributed energy, it can not only improve energy utilization efficiency, reduce energy consumption and emissions, but also promote the development of new power systems and renewable energy, making important contributions to achieving sustainable global energy development.
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  The Study on Assessing of Weak Links in the Stability of Distribution Networks with a High Proportion of New Energy Access and the Technology for Stabilizing and Regulating

  HAI Bin, LI Dashuang, ZHANG Zhiyuan, WANG Rui, SONG Zhenghang, YAO Jinke

  Journal of Northeast Electric Power University. 2024, 44(4): 9-20. https://doi.org/10.19718/j.issn.1005-2992.2024-04-0009-12

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  The intermittency and volatility of high-proportion renewable energy access to the power grid have a significant impact on system stability. Therefore, it is crucial to evaluate and improve the stability of distribution networks with high proportions of renewable energy sources（RES）。This paper proposes a new power grid strength evaluation index, the integrated short circuit ratio （ISCR），which not only considers the interaction between RES, but also considers the impact of energy storage devices （ESD），and can more accurately identify weak links in the power grid. In addition, based on ISCR, a distribution network stability improvement method is proposed to allocate the location and capacity of RES and ESD through a two-level optimization method to enhance system strength and increase the capacity of RES and ESD. In the upper level, the location and capacity of RES are optimized to ensure the maximum ISCR value at the node. In the lower level, the location and capacity of ESD are optimized to ensure that the ISCR value is higher than the critical short circuit ratio （CSCR）to maintain system strength. The location optimization is determined by the ISCR value at the node. The capacity optimization is solved using linear programming methods. Finally, a case study verifies the effectiveness of the proposed optimization method in maintaining grid strength while increasing the capacity of RES and ESD.
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  AC-DC Intrusion Signal Detection Method Based on Generative Adversarial Network for Secondary Panel Cabinet

  YIN Qingqing, HE Tao, WU Xin, JIN Zhaoying, GAO Xiaoting

  Journal of Northeast Electric Power University. 2024, 44(4): 21-27. https://doi.org/10.19718/i.issn.1005-2992.2024-04-0021-07

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  Based on the unpredictable AC-DC intrusion caused by human error or detection equipment failure in the terminal of secondary screen cabinet of substation relay protection, a new intrusion signal detection method based on generative adversarial network and principal component analysis is proposed to solve the problem of poor quality and small quantity of data samples. Gaussian kernel smoothing is used to preprocess the terminal data to reduce noise interference, and then the cleaned data is amplified through the generated adversarial network （GAN）to meet the subsequent principal component analysis processing and fault detection and identification of AC and DC intrusion signals. The identification accuracy of the proposed method reaches 95%，which realizes the accurate detection of the small sample fault data of the terminal of the secondary screen cabinet.
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  Synchronization Frequency Resonance Suppression in Grid-formed Inverters

  XIE Jun, LI Zhi, ZENG Chuihui, GUI Xi, WANG Wei, ZHANG Jie

  Journal of Northeast Electric Power University. 2024, 44(4): 28-37. https://doi.org/10.19718/j.issn.1005-2992.2024-04-0028-10

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  For the future of high power electronics penetration, the stable operation of grid-forming inverters in the power system is crucial. Due to the high inertia and high damping generated by the mechanical rotor and damping winding of the traditional synchronous machine, the inverter may have obvious synchronous frequency resonance problems in the output power after grid connection due to the lack of inertia and damping and the negative damping introduced by coupling, which not only affects the waveform quality, but also leads to transient instability in serious cases. Four methods are proposed and analyzed for this problem, and finally the simulation verification is carried out by Matlab/Simulink 
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  Investigating the Impact of Reactive Power Control Loops on the Transient Stability of Grid-Forming Inverters

  ZENG Chuihui , XIE jun , LI Zhi, YANG Yang , YAO Jun , ZHANG Jie

  Journal of Northeast Electric Power University. 2024, 44(4): 38-45. https://doi.org/10.19718/j.issn.1005-2992.2024-04-0038-08

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  With the transformation of the global energy structure and the improvement of environmental protection awareness, as an efficient and environmentally friendly way of energy utilization, the distributed generation system based on new energy is gradually occupying an important position in the power system. With the continuous improvement of the penetration rate of distributed generation system, the equivalent inertia of the power grid continues to decrease, which seriously affects the frequency stability of the power system. As a result, virtual synchronous control has emerged, which can compensate for inertia and equivalent damping of the grid by simulating the dynamic characteristics of traditional rotary synchronous generators. Although the small signal stability control of virtual synchronous machine （Virtual synchronous generators ,VSG）has been widely studied, the influence of its reactive power loop on the transient stability of the large signal of the system still needs to be further studied. In this paper, the influence of the reactive circuit of the grid-connected inverter on its transient stability is analyzed theoretically, and on this basis, three methods that can effectively improve the transient stability of the grid-connected inverter are listed. Finally, the simulation was verified by MATLAB/Simulink platform.
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  Master-slave Game Optimal Scheduling Strategy of Integrated Energy System Considering Integrated Demand Response

  YAN Gangui, CHEN Baihui, Wang Jiagi, Yan Han, Liu Weiyang, Yan Zhongwen

  Journal of Northeast Electric Power University. 2024, 44(4): 46-55. https://doi.org/10.19718/j.issn.1005-2992.2024-04-0046-11

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  In the context of facing the increasing number of stakeholders and the physical coupling of the regional integrated energy system, an innovative scheduling strategy is proposed, which takes into account the demand response of multiple parties and adopts a multi-subject game for optimization. First, the actual characteristics of different loads in each microgrid and the response behaviors of users are studied in depth, and a corresponding multi-load integrated demand response model is established. Then, a multi-subject master-slave game model is constructed by taking the system operator as the upper layer leader and the microgrid load aggregator, centralized energy storage plant and wind farm as the lower layer followers. In the upper layer model, the goal is to maximize the system operator's revenue from energy sales, and to determine the unit price of energy sales and compensation price of each microgrid through optimization. And in the lower layer model, it is committed to minimizing the comprehensive cost of all parties, and determines the energy supply of wind farms, the energy output between multiple devices in each microgrid, and the charging and discharging strategies of energy storage plants through optimization. In order to solve this complex problem, the particle swarm algorithm is finally used to solve the upper layer subject model and the Cplex solver is used to solve the lower layer slave model, which interact with each other to finally obtain the equilibrium strategy after the game.
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  Static Security Risk Assessment Static Security Risk Assessment of Electric-Gas Integrated Energy Systems for Digital Twins

  LIU Yijiang, CHEN Houhe

  Journal of Northeast Electric Power University. 2024, 44(4): 56-64. https://doi.org/10.19718/j.issn.1005-2992.2024-04-0056-09

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  In the energy transition environment, the electric-gas integrated energy system has developed rapidly. However, the increase of complexity also challenges the safe and stable operation of the electric-gas integrated energy system. In order to better evaluate the operational risk between the two, this paper presents a risk assessment method that can reflect the risk of the electric-gas integrated energy system by using digital twin technology. By monitoring and simulating the operating state of the digital twin model, the operational risk of the electric-gas integrated energy system can be evaluated effectively. This method has the advantages of high precision and reliability, and has a wide prospect in practical application. In this paper, the original data of the system during normal operation are calculated by ox method to obtain the operating state of the system voltage, pressure and power flow. Then, the integrated energy system risk index is calculated to generate a database, and finally the calculated index data is evaluated and predicted using CNN-XGBoost technology. The example results show that the method used can improve the accuracy and efficiency of safety risk assessment and prediction of electric-gas system well.
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  Low Carbon Scheduling of Electricity-gas-heat Integrated Energy System Based on Flexibility Supply-demand Balance

  HUANG Nantian, HU Chenhan, CAI Guowei, WANG Hefei, WANG Hao

  Journal of Northeast Electric Power University. 2024, 44(4): 65-76. https://doi.org/10.19718/j.issn.1005-2992.2024-04-0065-12

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  Renewable energy sources such as hydrogen, photovoltaics, and wind energy are important ways to achieve the dual carbon goals and carbon emission control goals. Due to the significant fluctuations in renewable energy generation, the dual risks of load loss and power abandonment are highlighted, which puts higher demands on the flexibility of energy systems. This article proposes a low-carbon scheduling model based on flexibility quantification for a high proportion renewable energy integrated energy system. Firstly, analyze the operational characteristics of flexible resources in multi energy coupled equipment, construct a comprehensive energy system flexible resource model, and combine the utilization and emission of carbon dioxide in system equipment to achieve deep utilization of carbon dioxide within the system；Secondly, considering the source load fluctuation of the system, combined with the quantitative difference in flexibility between the integrated energy system and the power system, the quantitative analysis of energy, power, and slope flexibility of the park system is achieved；Finally, combining the differentiated regulation characteristics of system flexibility resources with the supply-demand differences of system flexibility at different time scales, multi time scale scheduling is carried out to mitigate the flexibility requirements brought about by the uncertainty changes of renewable energy and small time scales of load. This article takes a comprehensive energy industrial park in the south as the experimental background, and uses the method proposed in this article to analyze and schedule, verifying the power and electricity balance of flexible resources at different time scales, which is conducive to improving the flexibility and low-carbon characteristics of the comprehensive energy electricity-gas-heat system.
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  Voltage Coordination Control Strategy for Zoning in Distribution Network with High Proportion of Photovoltaic

  MA Chenglian, LI Chuang, XUE Bing, YANG Jinsong, LIU Lize, YANG Mao, SUN Li

  Journal of Northeast Electric Power University. 2024, 44(4): 77-85. https://doi.org/10.19718/i.issn.1005-2992.2024-04-0077-09

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  With the increasing proportion of photovoltaic power generation connected to the distribution network, voltage out of limits and fluctuations have become increasingly serious. A voltage coordination control strategy for distribution network zoning is proposed to address this issue. In terms of distribution network zoning, based on the voltage sensitivity index information obtained from day-time power flow calculation, the voltage change index suitable for distribution network zoning is constructed by calculating the changes in the voltage of each node affected by photovoltaic active and reactive power regulation. The regional division of each node is determined based on the criterion that this index meets the voltage change threshold requirements；In terms of voltage coordination control of the zone, a voltage sensitivity control strategy within the zone is adopted to pair nodes and utilize the photovoltaic active and reactive power regulation ability to control all out of limit voltages within the zone to the normal range. Based on this, an interval distributed voltage coordination control strategy is adopted to achieve interval state variable equivalence and optimize the dynamic reactive power compensation of photovoltaic systems between adjacent zones based on the alternating direction method of multipliers （ADMM）algorithm, in order to achieve optimal suppression of expected voltage fluctuations across the entire network. Taking the IEEE 33 node system as an example, numerical analysis is conducted to verify the effectiveness of the proposed strategy.
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  Short-term Wind Speed Forecasting Based on ICEEMDAN-PSO-LSTM

  YU Na, WUYicheng, HUANG Dawei, KONG Lingguo

  Journal of Northeast Electric Power University. 2024, 44(4): 86-93. https://doi.org/10.19718/j.issn.1005-2992.2024-04-0086-08

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  This article proposes a short-term wind speed prediction method based on improved adaptive noise complete set empirical mode decomposition （ICEEMDAN）and particle swarm optimization （PSO）long and short term memory neural network （LSTM）models. Use ICEEMDAN algorithm to decompose daily wind speed data and calculate corresponding marginal spectra, and screen historical data based on spectral correlation；Using PSO algorithm to optimize LSTM neural network parameters, ICEEMDAN decomposition is performed on the input data, and multiple modal components obtained are predicted using PSO-LSTM. The wind speed prediction results are obtained by overlaying the predicted values of each component. Use the proposed method to predict the wind speed of a domestic wind farm, and verify the effectiveness of the proposed method through comparative analysis.
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  Post-disaster Fault Repair Strategy for Regional Interconnection Electric and Gas System Considering Dynamic Traffic Network

  YANG Xinhe, SUN Liang, WANG Weigiang, SHEN Chang

  Journal of Northeast Electric Power University. 2024, 44(4): 94-104. https://doi.org/10.19718/i.issn.1005-2992.2024-04-0094-11

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  In order to mitigate the impact of extreme events on the integrated energy system, restore various loads as soon as possible, and improve system flexibility. This paper proposes a fault repair strategy that considers the coordinated operation of the regional electric and gas system （IEGS）at the level of transportation and distribution networks. Firstly, a traffic flow allocation model considering the real-time recovery index correction of the system is established through the cellular transmission model to predict the traffic flow of the transportation network. Secondly, under the premise of fault pre allocation, a fault recovery model for regional IEGS is established to coordinate and optimize resources such as maintenance teams, distributed power supplies, and distribution network structures, to reduce outage losses. Then, using the minimum travel time matrix of the maintenance team and the road modification parameters of the traffic network obtained from the real-time recovery indicators of the system as transfer variables, at the time point when the maintenance team starts moving, the subsequent repair plan and the operation of the traffic network are recalculated, and the multi time section optimization is performed. Finally, the effectiveness of the proposed strategy is verified through a numerical simulation comparison. And analyze the impact of mobile energy storage devices on fault recovery.
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  Development of Wide-frequency Measurement Device based on Blackman Window ApFFT and Double-spectrum-line Correction

  LI Jin , YANG Yuanwei, GUO Fang , SHI Bonian

  Journal of Northeast Electric Power University. 2024, 44(4): 105-112. https://doi.org/10.19718/j.issn.1005-2992.2024-04-0105-08

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   In order to further analyze the influence brought by the increasingly obvious characteristics of power network electronization, the monitoring of power network operation condition extends to the direction of interharmonics and higher harmonics, and puts forward higher requirements for synchronous wide-frequency measurement. The windowed interpolation spectrum analysis method widely used in synchronous wide-frequency measurement has spectrum leakage, which will lead to large errors when the fundamental frequency is shifted or there are neighboring signals in the signal. To solve this problem, an improved wide-frequency phasor measurement method based on Blackman window all-phase FFT bispectrum line correction is proposed in this paper. The spectrum of wide-frequency signals is analyzed by combining all-phase FFT and Blackman cosine window, and the parameters are corrected by using bimodal spectral lines. This method can effectively improve the suppression effect of spectrum leakage, reduce the interference of adjacent spectrum, and improve the measurement accuracy of wide-frequency signal parameters in complex operating conditions of fundamental wave frequency offset or adjacent spectrum.
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  Short-term Power Load Forecasting Based on Density Peak Clustering and Improved LWLR

  WANG Chenyu , ZHANG Zhao , HOU Jialong , ZHOU Hongyan , CHEN Xuebo

  Journal of Northeast Electric Power University. 2024, 44(4): 113-120. https://doi.org/10.19718/j.issn.1005-2992.2024-04-0113-08

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  Short-term power load data are characterized by complexity and uncertainty, which often have an uncontrollable impact on the prediction results of the data. When short-term electricity load data are clustered and analyzed using traditional clustering methods, the prediction results will be biased due to characteristics such as the uncertainty of electricity load. In addition, considering that global regression forecasting methods are unable to use different modeling approaches for different parts of the data in the modeling stage, which limits the problem of adaptive capability for different distribution regions or different subsets of features. In this paper, we adopt the density peak clustering algorithm with K-nearest neighbor and weighted similarity to classify the features of short-term electricity load data, and propose a locally weighted linear regression model using K-nearest neighbor to forecast short-term electricity load. The advantages of this model are that it avoids the influence of Euclidean distance on the selection of cluster class centers, reduces the negative influence of global data on local data, avoids the centralized effect of cluster class division, and improves the generalization ability of the model. By comparing with fuzzy C-mean clustering and traditional global regression prediction methods, the model proposed in this paper is more superior for the prediction of real power data.