• Issue 6,2022 Table of Contents
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    • >科学研究
    • Overview of transient overvoltage mechanism and suppression strategies of high voltage direct current transmission grid

      2022, 37(6):3-16. DOI: 10.19781/j.issn.1673-9140.2022.06.001

      Abstract (415) HTML (0) PDF 1.54 M (604) Comment (0) Favorites

      Abstract:Commutation failure, DC blocking and near AC short-circuit fault of HVDC transmission system would lead to transient overvoltage of sending-end power grid, restrict transmission capacity and threaten safe and stable operation of system. For this reason, this paper firstly gives the similarities and differences of the transient overvoltage generation mechanism of DC sending-end power grid under three typical fault conditions of commutation failure, DC blocking and near-field AC fault are analyzed systematically, and the main influencing factors of transient overvoltage are clarified. Secondly, the existing transient overvoltage suppression strategies and their advantages and disadvantages are summarized. Finally, in view of the shortcomings of the existing research, it is analyzed that the three aspects of analyzing the transient overvoltage mechanism of different new energy transmission scenarios, revealing the coupling law of multiple influencing factors of transient overvoltage, and constructing a multi-temporal and spatial scale transient overvoltage collaborative suppression system are the focus of future research on transient overvoltage of HVDC sending-end power grid.

    • Life cycle optimal charging strategy based on the SOH of power lithium ion battery

      2022, 37(6):17-24. DOI: 10.19781/j.issn.1673-9140.2022.06.002

      Abstract (188) HTML (0) PDF 1.36 M (358) Comment (0) Favorites

      Abstract:In the view of the battery serious aging caused by the constant-current-constant-voltage(CC-CV) charging strategy which adopts the empirical charging current values, this paper proposes an improved CC-CV charging strategy. Firstly, with the goal of minimum decline capacity of battery, the database dynamic programming (DDP) is employed for the planning of the battery life cycle on the basis of the capacity decline model of lithium-ion battery. After that, the corresponding optimal charging current distribution under different cycle stages is obtained, and the influence of the charging current on the battery capacity decay is also analyzed. Finally, in MATLAB/Simulink simulation, the proposed strategy is compared with the existing CC-CV charging strategy. It is shown that this strategy can effectively extend the battery cycle life.

    • Main oscillation path identification of power grid based on mapping elastic potential energy increment

      2022, 37(6):25-34. DOI: 10.19781/j.issn.1673-9140.2022.06.003

      Abstract (130) HTML (0) PDF 1.29 M (355) Comment (0) Favorites

      Abstract:The boundary fluctuation of the actual power grid will cause the low-frequency oscillation, and the severe oscillation of some lines under the main oscillation path will seriously threaten the security and stability of the power grid. Therefore, the paper proposes an identification method of the main oscillation path under the boundary disturbance of the power grid. By comparing the similarities between power system and elastic mechanical system, the power grid is mapped into an elastic network, and a dynamic model of elastic mechanics is constructed to analyze the low-frequency oscillation of power grid from the perspective of mechanics. According to the energy conversion mechanism of forced vibration, the energy conversion characteristics of power systems under power oscillation are analyzed. Combined with the interaction and distribution characteristics of the network energy, the path oscillation index is established, and an identification method of main oscillation paths is proposed. The simulation results show that the dynamic mapping between power system and elastic mechanical system is reasonable, and the identification of main oscillation path is effective. The presented method is helpful to understand the physical process of low-frequency oscillation in power systems, and provides references to the relevant measures to suppress oscillation.

    • Expansion planning of urban power-gas interconnection energy system considering resilience enhancement

      2022, 37(6):35-45. DOI: 10.19781/j.issn.1673-9140.2022.06.004

      Abstract (136) HTML (0) PDF 1.17 M (401) Comment (0) Favorites

      Abstract:With the development of energy technology, the extended planning of integrated urban electricity and natural gas systems has become a hot issue. In recent years, the frequent occurrence of extreme natural disasters threaten the operation of the energy system. Under the background, the extended planning problem of integrated urban electricity and natural gas systems with consideration of resilience upgrading is addressed in this paper. Firstly, the basic components in the system are divided into disaster resistance levels to describe the damage of components after disaster in the extreme natural disaster scenario. Then, a robust optimization model of urban power gas interconnected energy system expansion planning considering elastic lifting is proposed to to minimize the sum of investment cost and load shedding cost by using energy storage batteries, distributed gas generators, gas storage tanks, power to gas devices and other equipment. Finally, the column and constraint generation algorithm are utilized to solve the proposed model. In addition, the improved IEEE 33 bus power system and Belgium 20 bus power system are chosen for simulation test. The planning results verifies that the proposed extended planning model can improve the system flexibility.

    • Coordinated transmission & distribution network expansion planning based on project-net revenue curve of distribution network

      2022, 37(6):46-54. DOI: 10.19781/j.issn.1673-9140.2022.06.005

      Abstract (122) HTML (0) PDF 1.15 M (380) Comment (0) Favorites

      Abstract:Transmission network planning and distribution network planning are all classical problems in power system. The coordination programing of these networks will lead to global optimal planning solution with the premise of a prescribed investment budget. In order to tackle the issue of combinatorial explosion in the coordinated planning, a bi-level calculation method based on the project-net revenue curve of distribution network is proposed. By solving the distribution network planning model repeatedly, project-net revenue curve is obtained and passed to the transmission network expansion model. This method significantly reduces the number of integer variables in the coordinated planning problem. In case studies, transmission & distribution testbed based on the modified Garver’s 6-bus system and the REDS-135 system verifies the effectiveness of the proposed method.

    • Optimization model of distribution network planning project based on benefit coupling and time series correlation characteristics

      2022, 37(6):55-61. DOI: 10.19781/j.issn.1673-9140.2022.06.006

      Abstract (108) HTML (0) PDF 1.08 M (258) Comment (0) Favorites

      Abstract:Under the limited investment budget, the best project combination problem is investigated for multiple distribution network projects with a high penetration new energy to achieve the highest reliability and economy. Considering the difference of marginal benefit of reliability in different power supply areas and the complex correlation between projects, an optimization model is proposed for the distribution network planning project. Firstly, the characteristics of benefit coupling and time series correlation are taken into account to establish the project benefit coupling equation. On this basis, the project benefit coupling characteristics are extracted. Secondly, the association characteristics of project time series are determined according to the definition of time series association rules. The relationship between distribution network planning projects are defined, and the constraints of distribution network planning projects are designed. Then, the optimization model is established to maximize the project investment benefit. In the end, two existing methods are compared and verified. It is shown that the proposed model is low in cost and high in benefit. It also provides a basis for the optimization of distribution network multi-area projects under limited budget.

    • A wind power dispatching strategy based on improved NashQ under multi-agent game

      2022, 37(6):62-72. DOI: 10.19781/j.issn.1673-9140.2022.06.007

      Abstract (144) HTML (0) PDF 1.75 M (271) Comment (0) Favorites

      Abstract:Aiming at the problem of renewable energy gaming in power generation market, this paper studies wind power dispatching strategies in different scenarios, and proposes an improved NashQ wind power dispatching strategy. Firstly, a wind power optimal dispatch model under a game environment is established. In the dispatch model, the punishment for wind power forecast error, the environmental and economic benefits of wind power, and the cost of the curtailment of renewable energy are all considered. On this basis, the dispatch strategies are compared for the independent wind power operation mode, wind-vehicle operation mode, and wind-storage joint operation mode. Secondly, The Jensen-Shannon divergence is introduced for the learning rate of the intelligent agents. The convergence efficiency of multi-agent reinforcement learning is then improved. Finally, a microgrid model is constructed in Matlab for simulation. It is shown that the improved NashQ method has a significantly higher convergence speed than the NashQ and NETRL algorithms, and the wind-vehicle joint operation model has a better performance in the market games.

    • Integrated optimal control strategy of loop-closing and loop-opening operation in distribution network

      2022, 37(6):73-81. DOI: 10.19781/j.issn.1673-9140.2022.06.008

      Abstract (174) HTML (0) PDF 1.12 M (351) Comment (0) Favorites

      Abstract:The loop-opening and loop-closing operation can avoid outage when switching power supply, thereby improving the reliability of distribution network. In order to ensure the safety of loop-closing operation as well as the economy and power quality after loop-opening, an optimal control strategy is proposed by considering the whole process of loop-closing and loop-opening operation in this paper. Compensation capacitors, transformer taps and distributed generation are utilized as control means. Meanwhile, the control target is set to minimize the times of device regulation before loop-closing and after loop-opening, the maximum load rate during loop-closing, the network loss and voltage deviation after loop-opening. Secondly, the historical load of distribution transformer is adopted to calculate the load power of distribution network, which improves the accuracy and real-time of power flow calculation. In addition, the multi-objective particle swarm optimization algorithm is applied to obtain the Pareto optimal set of control schemes. Finally, a practical example in different scenarios are included to verify the effectiveness of the proposed control strategy.

    • Study on temperature field distribution of pipe gallery cable based on finite element method

      2022, 37(6):82-90. DOI: 10.19781/j.issn.1673-9140.2022.06.009

      Abstract (127) HTML (0) PDF 1.98 M (322) Comment (0) Favorites

      Abstract:In order to solve the problem that high temperature of cables in comprehensive pipe gallery leads to disaster, the temperature field distribution and influencing factors of cables in comprehensive pipe gallery during operation are studied in this paper. Based on the finite element numerical model established by ANSYS, the distribution rule of temperature field of cable in pipe gallery is studied, and the influence of the distance between cable core layers, the distance between support layers and the current on the distribution of temperature field of cable is analyzed. The results show that when the distance between cables and support layers is greater than 0.6 m, the influence on the temperature distribution of cables is small. The cable spacing is suggested to be 0.2 m, and the distance between support layers is suggested to be 0.2 m. The main influence radius of cable temperature field in pipe gallery is 0.83 m, which is independent of cable current, cable spacing and support layer spacing. The electric flux of the cable is an ExpAssoc function related to the temperature of the cable during operation and the distance between the cable cores. The distribution of temperature field of the cable can be monitored online to calculate the size of the cable flow and monitor the load to ensure the safe operation of the cable.

    • Anomaly detection of distribution network voltage data based on improved K-means clustering k-value selection algorithm

      2022, 37(6):91-99. DOI: 10.19781/j.issn.1673-9140.2022.06.010

      Abstract (138) HTML (0) PDF 1.65 M (284) Comment (0) Favorites

      Abstract:K-means clustering algorithm has been applied to anomaly detection of large-scale distribution network data due to its advantages of fast computation speed and high accuracy. However, the algorithm may lead to an inaccurate clustering if the assumed clustering number is not appropriate. Therefore, this paper presents a clustering number selection algorithm IES based on the improved elbow method and silhouette coefficient (IES). Firstly, the clustering evaluation index of the elbow method and the upper limit of clustering number are utilized to set a threshold which can adaptively change with data sets. With this threshold, the lower limit of clustering number can be obtained. Secondly, the silhouette coefficient calculated within the upper and lower limit of the clustering number. An “one maximum” rule is proposedin order to improve the algorithm speed and avoid calculating all the silhouette coefficients. In the end, the calculated silhouette coefficients are utilized to select the appropriate clustering number. In addition, the recall rate is employed to evaluate the anomaly detection and illustrate the importance of selecting appropriate clustering number for K-means anomaly detection. Simulation results show that the IES algorithm can obtain the optimal clustering number adaptively, meantime, greatly shorten the calculation time, and improve the accuracy and efficiency of the K-means algorithm in online monitoring.

    • Voltage partition control method for distribution network with DG based on sensitivity clustering

      2022, 37(6):100-107. DOI: 10.19781/j.issn.1673-9140.2022.06.011

      Abstract (100) HTML (0) PDF 1.34 M (313) Comment (0) Favorites

      Abstract:A high proportion of distributed generations are connected to the distribution network, which can easily lead to voltage fluctuations and even voltage limit violations, and increase system network losses at the same time. To increase the safety margin of the distribution network and improve the reliability of power supply, this paper proposes a voltage partition control method for the distribution network with DG based on sensitivity clustering. First, power flow calculation is conducted to obtain the Jacobian matrix. Then, calculate the sensitivity of the voltage of each node to the output of the distributed generation, through which the reactive power voltage control space matrix of the DG can be obtained. Then clustering is performed by the K-means algorithm to obtain DG adaptive partition. Finally, according to the sensitivity and partition results, the output of DG and reactive power equipment is adjusted for voltage regulation. Voltage control of this method can perform directional compensation for the weak points of the system voltage, and realize the divisional adjustment of distributed generations. Finally, the IEEE 33-node system is used as an example, and the results show that the voltage control method can effectively improve the system voltage level and improve the power quality.

    • Pattern recognition of UHF signals in partial discharge considering electromagnetic model

      2022, 37(6):108-115. DOI: 10.19781/j.issn.1673-9140.2022.06.012

      Abstract (83) HTML (0) PDF 1.71 M (267) Comment (0) Favorites

      Abstract:Detection of partial discharge by UHF signal has become an ordinary operation and maintenance detection method for High Voltage GIS, transformers, and other equipment. However, this method indirectly detects PD intensity by measuring electromagnetic waves, so the accuracy of PD pattern recognition technology based on this method is not high, and has not been well solved. This paper introduces the cut-off frequency of TEm1 mode as the division basis of the time-frequency distribution of the PD UHF signal. The PD UHF signal excited by a single insulation defect is used for signal preprocessing, time-frequency distribution segmentation, feature parameter extraction and selection, PSO-ELM recognition, and other operations. Finally, the PD signal type can be accurately determined and the identification accuracy of insulation defect types in GIS can be improved. This segmentation method enhances the spatial distribution information of image features, and it is of great practical value to improve the accuracy of the UHF method in PD identification.

    • Low voltage experimental studies on mechanical stress wave induced by IGBT switch

      2022, 37(6):116-124. DOI: 10.19781/j.issn.1673-9140.2022.06.013

      Abstract (91) HTML (0) PDF 2.13 M (303) Comment (0) Favorites

      Abstract:Insulated gate bipolar transistor (IGBT) is the key power electronic device in the field of new energy power generation, smart grid and high voltage power transmission. The condition monitoring of IGBT is the basis for reliability monitoring of power electronic devices. Existing detection methods based on electromagnetic thermal parameters are difficult to meet the needs of fast, non-destructive, and online detection at the same time. In the switching state, mechanical stress wave signals generated due to the interaction of electromagnetic forces within the IGBT with multiple physical fields. The characteristic parameters of the signals can characterize the state of IGBT effectively, so it has the potential to become a new IGBT state monitoring method in the future. This paper studies the acoustic emission signals generated by different switching states of the IGBT under low voltage conditions from three aspects: signal generation mechanism, test system construction, and test result analysis. It is concluded that the IGBT generates acoustic emission signals both at the moments of switching on and switching off. The main components and frequency range of the signal are obtained. The peak of the acoustic emission signal pulse at the time of conducting is linearly related to the collector voltage VCE. High frequency electromagnetic waves are related to VCE. The pulse width affects the density of frequency points and acoustic emission signals even generated without VCE.

    • Big data recognition method for daily net load curve of substation bus based on SVM

      2022, 37(6):125-131. DOI: 10.19781/j.issn.1673-9140.2022.06.014

      Abstract (134) HTML (0) PDF 1.14 M (367) Comment (0) Favorites

      Abstract:In view of the accuracy and low time efficiency of the traditional load curve classification method based on statistics, the non-invasive load monitoring and decomposition technology is extended and applied to the bus load curve decomposition of substation in this paper. A method for identifying the daily net load curve of the bus based on SVM and SCADA big data is proposed by considering the output of new energy. Firstly, the change process of the load active power curve of typical industries is analyzed, and the active power mutation time for load pre-screening is extracted. Secondly, Fourier series are utilized to fit the active power waveform. The industry load feature tags are obtained, waveform features are extracted. In addition, for the purpose of identification of the industry load characteristics, the support vectors machine is employed for the waveform characteristics classification and recognization for the daily net load curve of the substation bus. In the end, a 330 kV substation in Gansu Power Grid is simulated by SCADA for verification. It is shown that this method can effectively classify the bus load, thereby improving the efficiency of load modeling.

    • A detection method for anomalies in protection relay setting based on the

      2022, 37(6):132-137,149. DOI: 10.19781/j.issn.1673-9140.2022.06.015

      Abstract (146) HTML (0) PDF 1.71 M (288) Comment (0) Favorites

      Abstract:Nowadays, the scales of power systems are enlarging, the types of input power sources are increasing, and the energy demands are also raising. Hence, the disturbance in grids become more frequent, which request a more reliable protection relay system. To achieve the timely response for the potential disturbances in protection relay systems, this paper establishes anomaly detection method for warning and analyzing such disturbances. Firstly, the Kernel Linear Discriminant Analysis (KLDA) model is utilized to reduce the dimensionality of input data, thus to decrease the computation burden and accelerate the response. Then, the Influenced Outlierness (INFLO) anomaly detection is designed. This model can find the outliers in time according to the common range of operation setting parameters, and thus to swiftly response to anomaly conditions. Finally, an empirical study which is based on the protection relay system in one operating distribution network is conducted. The results show that the performance of the proposed method is satisfying, and can be deployed to monitor or manage the countermeasures for potential risks.

    • Analysis on peak shaving effect and needs of all parties based on incentive demand response considering response characteristics of EV users

      2022, 37(6):138-149. DOI: 10.19781/j.issn.1673-9140.2022.06.016

      Abstract (123) HTML (0) PDF 1.27 M (248) Comment (0) Favorites

      Abstract:Aiming at the security problem caused by the increasing peak load of distribution network with charging load, an incentive demand response (DR) is established and the response characteristics of electric vehicle (EV) users is considered. Firstly, the incentive mechanism is proposed that takes into account the effect of peak load reduction and the response degree of users. Secondly, the response characteristics are analyzed for contracted users and the model for evaluating the user's contract response times limit is proposed. The model of user response is then established with the consideration of the over response and under response. In addition, a cost and benefit model of grid company, aggregators and EV users participating in DR is established, and an optimization method of benchmark compensation price is proposed. Finally, simulations are examined to investigate the impact of the contracted users charging behaviors, the benchmark compensation price and charging power on load response. This research provides a reference for aggregators to screen contracted users, set different contract requirements, and adjust compensation electricity prices.

    • Research on BPA oriented short circuit current calculation for zero sequence parameters of primary equipment

      2022, 37(6):150-156,197. DOI: 10.19781/j.issn.1673-9140.2022.06.017

      Abstract (205) HTML (0) PDF 1.73 M (299) Comment (0) Favorites

      Abstract:At present, when planning the expansion of power grids, the range of zero-sequence parameter of the new planning equipment is relatively wide and lacks references, which affects the credibility of the result of single-phase short-circuit current. Thus, a zero-order parameter selection method based on the PSD-BPA platform for power grid expansion planning is proposed. Taking each partition of a local power grid as a typical scenario, the influence of the changes of zero sequence parameter XO card of 500 kV main transformer, zero sequence parameter LO card of 220 kV line, and sub equivalent zero sequence parameter XR card value of high-voltage side bus of 220 kV main transformer on single-phase short-circuit current of 220 kV side bus in that scenario of the BPA transient stability are analyzed. The key influencing factors are identified through error analysis, then according to the requirements of the calculation error, give advices to zero sequence of accessor according to the included important factors. An example analysis shows that the proposed method can easily and effectively evaluate the single-phase short-circuit current of bus at 220 kV side of Shanghai power grid 500 kV substation in the planning year, and can be applied to engineering practice.

    • Three-phase virtual flux linkage observation grid-connected inverter prediction technology

      2022, 37(6):157-164. DOI: 10.19781/j.issn.1673-9140.2022.06.018

      Abstract (102) HTML (0) PDF 2.27 M (360) Comment (0) Favorites

      Abstract:When analyzing the traditional three-phase grid-connected inverter model system, it is found that the use of a control strategy based on the orientation of the flux linkage of the virtual grid can effectively reduce the additional cost of the system and greatly improve the operation reliability of the system. However, when analyzing the traditional flux linkage observation without compensation, the phase angle offset problem is likely to cause system errors. In order to solve the problem, the flux linkage observer model scheme with LPF compensation is proposed in this paper, and the new design of capacitor voltage observer and grid voltage observer is studied. Combined with the deadbeat predictive current control algorithm, the traditional deadbeat control has been deeply studied, and it is found that there is a certain degree of control delay. An improved deadbeat current predictive control is proposed for improvement, and increase the sampling current at the time of prediction k+2 to make the anti-disturbance performance better. Finially, the experiments of the three-phase without AC voltage sensor estimation strategy combined with the improved deadbeat predictive current control algorithm is carried out, and the experimental results verify the effectiveness of the proposed strategy.

    • Research on forecasting electricity consumption of high-energy-consuming industries based on Granger causality and ARDL model

      2022, 37(6):165-172. DOI: 10.19781/j.issn.1673-9140.2022.06.019

      Abstract (165) HTML (0) PDF 1.16 M (273) Comment (0) Favorites

      Abstract:In order to explore the coupling relationship between the industrial economic development and power big data, a vector auto regressive (VAR) model is constructed between the electricity consumption of high-energy-consuming industries and the data of multiple economic indicators. By using the Granger causality test method, industrial economic index data are extracted that has a significant impact on electricity consumption forecasting. Based on this, an Auto Regressive Distributed Lag (ARDL) model of electricity consumption is established in high-energy-consuming industries that takes economic factors into account. An example analysis of industrial electricity consumption and economic data in a certain region from 2016 to 2020 shows that the Granger causality test can effectively dig out the economic indicators related to the electricity consumption of subdivided industries. Considering these economic factors in the regression model, the prediction accuracy of the model is effectively improved.

    • An improved cross double network locking reclosing signal coordination mode and its risk analysis

      2022, 37(6):173-180. DOI: 10.19781/j.issn.1673-9140.2022.06.020

      Abstract (118) HTML (0) PDF 1.44 M (331) Comment (0) Favorites

      Abstract:At present, 110 kV lines of smart substation mostly adopt double line protection, and the process layer double network is configured for each protection. Due to the inconsistent specifications in the early stage planning of smart stations, there is a potential cross-dual network problem in the double protection lock-reclosing coordination mode of some smart stations. In view of this, this paper studies the dual protection network structure of 110 kV transmission lines, and analyzes the coordination logic of mutual lock-reclosing of dual protections. An improved cross double network locking reclosing coordination mode is proposed. The calculation method of cross-network communication risks of substation blocking reclosing signals is given. Then the 110 kV double lines of 220 kV smart substation are taken as an example for case analysis, the results show that the proposed method greatly improves the communication reliability. Finally, the data in an actual substation is taken to calculate the risk of the method, which provides a guideline for improving the reliability of intelligent station cross dual network communication.

    • Big data mining of industry power consumption based on component index about seasonal-adjusted load

      2022, 37(6):181-189. DOI: 10.19781/j.issn.1673-9140.2022.06.021

      Abstract (80) HTML (0) PDF 1.42 M (211) Comment (0) Favorites

      Abstract:Under the background of energy digital economy, in order to display and analyze power consuming behavior, and to explore regional economic trends, this paper proposes a periodic adjusted load component index by referring to the stock market index. Firstly, some representative enterprise users are selected as samples based on given rules. Then, the periodic components of the selected user's historical daily electricity quantity are extracted by STL. Hence, the adjustment of the daily electricity quantity can be calculated, and the working strength coefficient is proposed. Then, according to the industry and individual differences, multiple indices are proposed, and the cycle adjusted daily load is weighted and integrated by fuzzy expert evaluation method. After that, based on a selected day’s value, the load trend can be displayed. Finally, the analysis shows that the working strength coefficient is helpful to link with the actual production activities, and the load index can reflect regional daily electricity consumption behavior. Furthermore, after neglecting the influence of temperature, the index has a strong correlation with economic indicators, which can explain the relationship between investment, output and production, and represent the economy of social subject.

    • >技术应用
    • Early warning method of power line insulation fault based on fuzzy logic algorithm

      2022, 37(6):190-197. DOI: 10.19781/j.issn.1673-9140.2022.06.022

      Abstract (174) HTML (0) PDF 1.45 M (320) Comment (0) Favorites

      Abstract:In view of the insulation fault of transmission lines, passive maintenance and prevention are mostly adopted, which can not realize real-time monitoring and early warning. In this paper, the mechanism of pollution discharge and traveling wave generation is analyzed. The analysis results indicate that the insulation fault generates periodical traveling wave. The more serious insulation performance decreases, the greater amplitude and the shorter period of the traveling wave generated. According to the characteristic mentioned above, fuzzy theory is used to realize the early warning. The amplitude and time interval of the fault traveling wave are taken as the input, and the degree of fault warning is taken as the output. Moreover, the fuzzy relation is determined to establish the fuzzy rule base, so as to realize fuzzy early warning. The field test results show that the electric power line insulation fault early warning system has high identification sensitivity, which can predict the insulation performance of the line insulator accurately.

    • Power operation oriented approach of work ticket segmentation and work information extraction method

      2022, 37(6):198-205. DOI: 10.19781/j.issn.1673-9140.2022.06.023

      Abstract (155) HTML (0) PDF 4.53 M (489) Comment (0) Favorites

      Abstract:The key information of system operation contained in the power work ticket is an important basis for pre-operation risk assessment. In order to quickly and accurately extract the required information from the actual work ticket document, a method of power work ticket segmentation and information extraction is proposed. First, the binarization, expansion, and corrosion operations are utilized to extract the table frame lines from the power work ticket image. Then the segmentation operations are performed to obtain cell images of the work ticket based on the frame lines detection results. The optical character recognition (OCR) is further leveraged to detect the corresponding information in the cell. Finally, the recognition result is structured based on the regular matching method to realize the effective extraction and matching of power operation information. Experimental tests based on actual work tickets show that the proposed method can combine the extracted power operation information in a contextual and semantic combination, and the key information recognition effect is better than general commercial OCR software.

    • Non-invasive arc fault recognition based on current mode decomposition

      2022, 37(6):206-211. DOI: 10.19781/j.issn.1673-9140.2022.06.024

      Abstract (116) HTML (0) PDF 1.74 M (233) Comment (0) Favorites

      Abstract:In recent years, electrical fires occur frequently. Arc fault is a important causes of electrical fires. In this paper, considering the characteristics of the low-voltage customer scenarios, the research of non-invasive arc fault detection is carried out. First, the aggregated load current waveform data is acquired at the entrance of the customer's power supply. Then, the amplitude and phase information of the fundamental and each harmonic wave of the total current is obtained by harmonic analysis. Next, the total current and the current characteristic parameter matrix obtained from training are used together to construct the objective function and form a multi-load current decomposition model. Finally, the intelligent optimization algorithm is adopted to optimize the solution to obtain the operating state of each appliance (including the fault states), and identify the arc fault and analyze its causes. In addition, this paper carries out the simulation experiment of arc fault for common appliances of actual low-voltage users in the laboratory, and the experimental results show that the proposed non-invasive arc fault recognition method is effective.

    • Research on energy saving and loss reduction method of three-phase unbalanced power grid based on stochastic fuzzy power flow

      2022, 37(6):212-218. DOI: 10.19781/j.issn.1673-9140.2022.06.025

      Abstract (105) HTML (0) PDF 1.15 M (324) Comment (0) Favorites

      Abstract:In order to effectively reduce the power loss caused by three-phase imbalance in distribution network, an energy saving and loss reduction method of three-phase imbalance distribution network based on random fuzzy power flow is proposed. This paper analyzes the harm of three-phase unbalanced distribution network, and obtains the unbalanced degree of distribution network and active power loss of line. Considering the uncertain influence of three-phase balanced distribution network load, the random fuzzy compatibility method is used to perform fuzzy modeling of the loads of distribution networks. The obtained fuzzy input variables are introduced into the power flow model to construct a three-phase unbalanced fuzzy power flow model, which can be utilized to calculate the active power loss of distribution network. The objective function including energy saving and loss reduction is constructed, and the dynamic change factor particle swarm optimization algorithm is used to obtain the optimal solution, so as to achieve energy saving and loss reduction of distribution network. The case study shows that the proposed method can achieve energy saving and loss reduction of distribution network under the condition of three-phase imbalance, and the objective function has good convergence performance and high efficiency of energy saving and loss reduction.

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