ISSN 1000-1026
CN 32-1180/TP
  • ISSN 1000-1026
  • CN 32-1180/TP

Volume 43,Issue 20,2019 Table of Contents

Display Type:      

Basic Research
Bi-level Optimal Configuration of Park Energy Internet Considering Multiple Evaluation Indicators
LIN Xiaoming, ZHANG Yongjun, CHEN Boda, FAN Suchun, CHEN Zexing
2019, 43(20): 8-15.DOI: 10.7500/AEPS20180811006
[Abstract](129)[PDF 1.43 M](57)
Under the background of adhering to the path of sustainable energy development, park Energy Internet has become an important development trend in the energy field. A typical structure of park Energy Internet is built, and the models of energy equipment are established. The evaluation indicators are put forward, including comprehensive energy self-sufficiency rate, comprehensive energy utilization rate and energy shortage expectation. Furthermore, a bi-level optimal configuration model is proposed taking into account the above multiple evaluation indicators. The proposed model considers the energy shortage penalty cost for N-1 failure of energy equipment, as well as the constraints of comprehensive energy self-sufficiency, comprehensive energy utilization rate and energy shortage expectation, and a hybrid algorithm combined with cataclysmic genetic algorithm and CPLEX solver is developed to solve the model. Finally, the study of a typical residential area is carried out where the results suggest that the planning method can balance the economics, energy sustainability, efficiency and reliability of the system.
Assessment Model of Solar Energy Accommodation Capability of Regional Integrated Energy System with PVs and Solar Collectors
WEI Wei, JIA Haoyue, MU Yunfei, WU Jianzhong, JIA Hongjie
2019, 43(20): 16-23.DOI: 10.7500/AEPS20181008008
[Abstract](92)[PDF 1.57 M](43)
It is significant to reasonably access solar energy accommodation capability in constructing a green, clean and low-carbon energy system. In view of the solar energy accommodation problem of regional integrated energy system with PVs and solar collectors, a two-stage robust model considering both the uncertainties of solar irradiance and the constraints of system operation is proposed for the assessment of solar energy accommodation in a regional integrated energy system. Firstly, the evaluation indices are developed based on the first law of thermodynamics. Then, a second-order cone model of distribution network and a linear energy flow model of thermal network are used to construct a two-stage robust assessment model for improving the solvability of the model. Finally, the case study proves that comprehensive utilization of solar energy can improve its accommodation capability. The impacts of irradiance fluctuations, power grid losses, the types of combined heat and power(CHP)units and the uncertainty budgets on solar energy accommodation capability are also carefully analyzed through case study.
Assessment Method of Accommodation Capacity of Renewable Energy Based on Non-time-series Model
ZHANG Zhenyu, WANG Wenzhuo, ZHANG Gang, WANG Zhiwei, MA Xiaowei, CHU Yunlong
2019, 43(20): 24-30.DOI: 10.7500/AEPS20180827012
[Abstract](88)[PDF 1.47 M](30)
With the rapid growth of installed capacity of wind and solar power, the problem of wind and solar power curtailment has become increasingly prominent. It is of great significance to conduct the research on the accommodation capacity of renewable energy and establish the quantitative evaluation system of accommodation capacity for operation and control of grid dispatching. An assessment method of accommodation capacity of renewable energy based on non-time-series model is presented in this paper. Firstly, the probability distribution of theoretical output of renewable energy is obtained based on Archimedes Copula function. The probability distribution of accommodation space of renewable energy in the system is built based on load characteristics, and the probability distribution of electric power curtailment is obtained. Then, the rate of electric power curtailment of renewable energy is calculated according to the probability distribution of electric power curtailment of renewable energy, which evaluates the accommodation capacity of renewable energy in the system. Finally, the correctness and effectiveness of the proposed method are verified by EPRI 36-unit system and the effects of load, installed capacity of renewable energy, peak regulating rate of conventional units and backup level on the renewable energy curtailment ratio are analyzed.
Imprecise Probabilistic Prediction of Photovoltaic Power Ramp Event Considering Daily Periodic Effect
ZHU Wenli, ZHANG Li, YANG Ming, WANG Bo, ZHAO Yuanchun
2019, 43(20): 31-38.DOI: 10.7500/AEPS20190131003
[Abstract](97)[PDF 1.33 M](40)
Reliable prediction of photovoltaic power ramp event is very important for power system operation. To avoid false and missing report, an imprecise probabilistic prediction method of photovoltaic power ramp event considering daily periodic effect is proposed. Firstly, new ramp characteristic is defined, which can effectively eliminate the daily trend change of photovoltaic power. Then, the optimal credal network(CN)is constructed by structure learning to implement the imprecise probabilistic prediction of solar power ramp events, so that the prediction error caused by the limited sample is avoided. Specially, imprecise Dirichlet model(IDM)with multi-state random variables is used to evaluate the imprecise conditional probability associated with nodes of CN. Finally, according to the given meteorological conditions, the probability interval of ramp events is inferred. The effectiveness of the proposed method is verified by the data of a photovoltaic plant. The results show that the proposed method can effectively capture the mutation events caused by meteorological conditions of change of photovoltaic power.
Adaptive Robust Day-ahead Optimal Dispatch for Urban Smart Photovoltaic Storage and Charging Tower
GAO Shengyu, LIU Zhihang, WEI Zhinong, CHENG Lexiang, ZHANG Linghao, TAN Kang
2019, 43(20): 39-48.DOI: 10.7500/AEPS20181002001
[Abstract](87)[PDF 1.36 M](36)
The co-optimization dispatch of sub-systems for smart photovoltaic(PV)storage and charging tower contributes to the realization of economical and efficient operation for the charging tower. Considering the influence of uncertainty on day-ahead dispatching, an adaptive robust day-ahead energy-reserve co-optimization dispatching method for PV storage and charging tower is proposed. Firstly, aiming at the minimum of daily operation cost, the day-ahead energy-reserve dispatch and real-time energy balance regulation are employed as first-and second-stage decisions, respectively, a tri-level optimization dispatch model of adaptive robust for the PV storage and charging system is established. Then, aiming at the problem that it is difficult to solve the tri-level optimization model directly, representative scenarios are used to describe the uncertainty, auxiliary variable is introduced to replace the worst-scene operation cost to deal with the inner decoupling replacement, so the tri-level model is transformed into the single-level robust optimization model with a limited number of scenarios. Moreover, an iterative algorithm for binding scenario identification is proposed to promote the computational efficiency of the model, where the master problem is the single-level robust model considering a few binding scenarios, which are identified by the sub-problem. Finally, the effectiveness of the algorithm is verified by the simulation of practical PV storage and charging tower in Nanjing, China.
Economic Analysis on Peak Shaving of Combined Heat and Power Plant with Electric Boilers in Auxiliary Service Market of Northeast China
LYU Quan, DU Siyao, LIU Le, ZHANG Na, WANG Haixia, LIU Rao
2019, 43(20): 49-56.DOI: 10.7500/AEPS20181119002
[Abstract](85)[PDF 1.47 M](38)
The heat and power decoupling retrofit of combined heat and power(CHP)units with electric boilers is an effective way to improve the downward peak shaving and accommodate the curtailed wind power. In order to analyze the retrofitting economy of the mainstream power units, by taking the peak-shaving auxiliary service market of Northeast China as background, the coordination model of CHP with electric boiler, the coal saving model for accommodating curtailed wind power, the costs and profits model for downward peak shaving, and investment economic evaluation model with the index of pay-back time period are built. On the basis of the real data, the economics of typical CHP units in the Northeast China power grid are calculated in different scenarios. The results show that, in the current peak shaving mechanism, when the heat load is large during the heat-supply medium term, for small-scale wind curtailment, the CHP plants have no motivation to use electric boiler for accommodation; for the large-scale wind curtailment, the CHP unit needs to be equipped with large-capacity electric boiler to obtain the positive benefits, which increase the risk for new investment. Through analysis, it shows that reducing the minimum output of the CHP units can reduce the capacity of the electric boiler, and thereby improve the economics of providing downward peak shaving service.
Classification Method of Unbalanced Power Consumption Data Based on Prior Knowledge and Deep Boltzmann Machine Sampling
WANG Kailiang, LU Jun, XU Zhiqiang, QI Zengqing, GONG Gangjun, WANG Yun
2019, 43(20): 57-64.DOI: 10.7500/AEPS20181128004
[Abstract](56)[PDF 1.54 M](24)
The existing customer labeling system in the smart grid construction process is not perfect. In the classification management of electricity data for massive users, there is a problem of small sample data and unbalanced distribution of labels. This paper proposes a classification method of unbalanced electricity data based on prior knowledge and deep Boltzmann machine(DBM)sampling. Firstly, the characteristics of load curve are extracted, the sampling principle is established, and the prior knowledge and DBM are used to sample the load curve. Then, the sample data are trained through the extreme learning machine(ELM)network. Finally, the Irish users' electricity data are used as the data source. Contrastive experimental analysis results of original non-sampling, random oversampling and synthetic minority oversampling technique(SMOTE)show that the proposed method can better classify the unbalanced electricity data sets, realize the analysis of the user's electricity usage behavior, and effectively support the peak shifting and peak avoidance at user side.
Daily Load Curve Clustering Method Based on Feature Index Dimension Reduction and Entropy Weight Method
SONG Junying, HE Cong, LI Xinran, LIU Zhigang, TANG Jie, ZHONG Wei
2019, 43(20): 65-72.DOI: 10.7500/AEPS20181115008
[Abstract](63)[PDF 1.33 M](31)
Daily load curve clustering is the basis of analyzing load characteristics under the background of load modeling. In view of the shortcomings of existing clustering methods in terms of clustering quality and clustering efficiency and based on the principle of fuzzy C-means and entropy weight method, a method of daily load curve clustering based on dimensionality reduction of feature index and entropy weight method is proposed. Firstly, seven kinds of feature indices of dimensionality reduction such as daily load rate, daily peak-to-valley difference rate and daily maximum utilization time are extracted and taken as the clustering input to replace the load data of each sampling point. Secondly, the entropy weight method is introduced to configure the weight coefficient of each feature index adaptively. Finally, the power load curves are clustered with the feature-weighted fuzzy C-means(FW-FCM)clustering algorithm. The daily load curves of a region are clustered using the proposed method. Results show that the method has certain advantages in operating efficiency, robustness, clustering quality and so on. Moreover, the clustering results can reflect actual power consumption characteristics of the load truly and effectively.
DC Active Power Adjustment Method Based on AC/DC Steady-state Security Region Considering Time Characteristics
CHEN Zhong, ZHU Zhengguang, YAN Jun, CHEN Hui
2019, 43(20): 73-81.DOI: 10.7500/AEPS20180917012
[Abstract](76)[PDF 1.40 M](35)
With the increasing wide-area coupling of the state and control variables of AC/DC hybrid systems, the time response characteristics of components vary greatly, and the control objectives of the system are difficult to achieve due to the uncoordinated time scale of each control parameter. To solve the above problems, firstly, description method of two-dimensional projection for AC/DC hybrid system and linear regression fitting algorithm for boundary surfaces are studied based on the theory of steady-state security region. Taking the security region and time parameters of control equipment into account, a general model for controlling the security region and the optimal adjustment curve in the region with time characteristics is proposed. Then, through the calculation of the main circuit parameters of high voltage DC transmission, the steady-state relationship between the active and reactive power compensation, the firing angle, the extinction angle and the transformer tap is analyzed. Then, the description method of security region is controlled by combinating with time characteristics. The method completes the characterization of the DC active power control region, and gives the optimal adjustment curve in the region to achieve the goal of minimizing system voltage fluctuations during the entire regulation time, thus guaranteeing the global stability and security of the AC/DC system in time dimension. Finally, using the modified two-area four-machine AC/DC hybrid system, simulation calculations verify the correctness and reliability of theoretical analysis.
Description Method of Radial Constraints for Distribution Network Based on Disconnection Condition of Power Supply Loop
XU Chengsi, DONG Shufeng, ZHU Jiaqi, ZHU Bingquan, XU Lizhong
2019, 43(20): 82-89.DOI: 10.7500/AEPS20180904011
[Abstract](67)[PDF 1.98 M](34)
The radial topology of distribution network is an important constraint condition to be considered in the analysis of distribution network. However, the mathematical models describing the topology of distribution network at present are all complex, which affects the efficiency of problem solving. In order to equivalently describe the radial constraint of distribution network and reduce the scale and complexity of the mathematical model, a description method of radial constraints based on disconnection condition of power supply loop for the distribution network is proposed. First, based on the concept of distribution power supply loop, a sufficient and necessary condition for the distribution network to satisfy the radial topology is proposed. Meanwhile, an algorithm for searching all the power supply loops in the distribution network is proposed. Then a method of linear transformation between the state of the path and the state of the branch is proposed. Finally, the proposed method is applied to the feeder service restoration reconfiguration in the distribution network. An IEEE distribution system and an actual distribution network of a provincial capital city are used to compare the calculation performance of different description methods of radiant constraints, which verifies the effectiveness and practicability of the proposed method.
Capacity Allocation Strategy for Full Compensation of Load Voltage in Unified Power Quality Controller with Energy Storage
MA Qian, WANG Wenli, XU Qian
2019, 43(20): 90-96.DOI: 10.7500/AEPS20181215003
[Abstract](53)[PDF 1.66 M](29)
In order to achieve coordinated power distribution between series and parallel units, the conventional compensation strategy of unified power quality conditioner(UPQC)with energy storage will cause phase jump of load voltage before and after compensation, which has an effect on the phase jump sensitive load. Therefore, this paper proposes a capacity allocation strategy for full compensation of load voltage amplitude and phase in UPQC with energy storage. The proposed strategy enables the load voltage to be fully compensated. By using the characteristic that the energy storage unit is able to provide active power, the appropriate parallel compensation current is selected and its amplitude is kept constant, which reduces the amplitude of the compensated power supply current. Thus, the series unit keeps a low compensation capacity, and the capacity configuration of series unit of UPQC is reduced. The results of simulation and low-voltage small-power prototype experiments show that the proposed strategy can achieve full compensation of load voltage and reduce the compensation capacity of series unit of UPQC.
Detection Method of False Data Injection Attack on Power Grid Based on Improved Convolutional Neural Network
LI Yuancheng, ZENG Jing
2019, 43(20): 97-104.DOI: 10.7500/AEPS20180919001
[Abstract](82)[PDF 1.38 M](35)
False data injection attack(FDIA)could tamper with measurement information collected by supervisory control and data acquisition(SCADA)system, which affects important decisions of power grid and threatens the state estimation of smart grid. Aiming at the state estimation of smart grid, the principle of FDIA under the communication model is studied, and a FDIA detection model based on improved convolutional neural network(CNN)is constructed. By adding the gate recurrent unit(GRU)to the fully connected layer in CNN, the CNN-GRU network is designed, which trains and updates network parameters based on historical measurement data of power grid, extracts spatial and temporal characteristics of the data and implements efficient and real-time FDIA detector based on the proposed model design. Finally, in the IEEE 14 bus and IEEE 118 bus test systems, a large number of comparative experiments based on traditional CNN, recurrent neural network and deep belief network are carried out to verify the effectiveness of the proposed method.
Application Research
Research and Development of Complex Event Processing Engine for Power Grid Online Analysis
ZHOU Mike, FENG Donghao, FENG Changyou, ZHANG Siyuan, YUAN Qihai, CHEN Jie
2019, 43(20): 105-113.DOI: 10.7500/AEPS20180910003
[Abstract](104)[PDF 2.45 M](41)
Complex event processing(CEP)engine software system for real-time stability assessment and event-driven rule evaluation is developed for fast(secondary)response requirements of power grid online analysis systems. Firstly, architecture design of CEP engine system, implementation technical ideas and main steps of relative software function modules are presented. Secondly, potential approaches to apply CEP technology to online analysis are discussed, including fast online security assessment, real-time tracking of power grid operation state, operation situation awareness of power grid and system-wide monitoring usage scenarios.
Network Simplification and Formation of Black-start Zone Partitioning Scheme Considering System Observability
GU Xueping, ZHOU Guangqi, LI Shaoyan
2019, 43(20): 114-122.DOI: 10.7500/AEPS20190110006
[Abstract](59)[PDF 1.31 M](24)
The wide-area phasor measurement system based on phasor measurement unit can reflect the real-time dynamic changes of power system, and the restoration process would be quicker and safer with the help of the real-time measurement information, which brings new opportunities to restoration of power system after blackouts. Firstly, optimal problem of black-start zone partitioning scheme is combined with wide-area phasor measurement system, and an integer linear programming model for black-start zone partitioning considering system observability is established. In addition to meet the constraints such as partitioning power balance, connectivity of subsystems, the operation status constraints of specific lines and minimum scale of subsystems, the requirement that whole grid and tie-line nodes can be observable is integrated into the model as linear constraint. Furthermore, the topology graph is simplified according to the nodes whose observability degree is 0 and some of nodes whose observability degree is 1. Thus, the scale of decision space is reduced and the computational efficiency will be improved. The experimental results of IEEE 118 system verify the effectiveness of the proposed model and system simplification method, and the extensibility of proposed model has been further indicated.
Optimization Design of Static Var Compensator and Its Control Strategy for Subsquent Commutation Failure with Grounding Fault
WANG Wei, ZHAO Mengyang, TANG Xiaobo, LEI Jie, LIU Fusuo
2019, 43(20): 123-129.DOI: 10.7500/AEPS20190117005
[Abstract](76)[PDF 1.48 M](32)
In view of the operation risks and faults in the construction process of high-voltage direct current(HVDC)transmission, this paper takes the common grounding faults on the AC side as the solved problem orientation to explore the optimization design method of static var compensator(SVC)and its new control strategy and then to improve the ability of resisting the subsequent commutation failure to ensure the stability of transmission system with grounding fault. Based on the voltage drop of the convert bus when the fault occurs, the comparison between theoretical analysis and results show that when the inductor capacity in fixed capacitor(FC)and thyristor control reactance(TCR)is properly configured, and the FC switching and TCR firing angle are optimized and controlled logically in the process of reactive power compensation, it could not only effectively resist the risk of subsequent commutation failure, but also solve the voltage ‘reverse adjustment' in the SVC compensation process.
Analysis on Excitation Loss Characteristics of Synchronous Condenser and Its Influence on Direct Current System
GUO Zhilin, HAO Liangliang, CHEN Zhengguang, LI Yanjun, ZHAN Rongrong, WANG Guang
2019, 43(20): 130-137.DOI: 10.7500/AEPS20181213007
[Abstract](102)[PDF 1.78 M](42)
The study on the excitation loss fault of the new synchronous condenser(SC)could be beneficial to the full advantage of its reactive power support in high-voltage direct current(HVDC)system. Firstly, different types of excitation loss faults are considered. Based on the actual recorded data, a single machine infinity system is taken as an example to qualitatively analyze the characteristics of excitation loss and its influence on DC system. Secondly, Ximeng—Taizhou HVDC system of China with SC and its excitation control system are established by PSCAD/EMTDC. Taking the SC connected at the receiving end as example, the impact of SC with excitation loss on HVDC is simulated with different voltage dips and different excitation loss types. The research indicates that the excitation loss of SC open-circuit at the receiving end may cause more serious consequences in the system than excitation loss of short-circuit. Moreover, the SC with excitation loss may deteriorate the operation condition of the system under the critical state of commutation failure.
Evaluation Method of Protection Configuration Scheme for Distribution Network
SHEN Yunchao, WANG Huifang, HUANG Zhihua, YANG Tao
2019, 43(20): 138-145.DOI: 10.7500/AEPS20180912012
[Abstract](97)[PDF 1.29 M](42)
One distribution network often has several kinds of protection configuration schemes because of loose requirements for distribution system protection. An evaluation method based on energy loss as performance evaluation index is proposed to quantitatively compare the performance of different protection configuration schemes. Firstly, the calculation and comparison model of energy loss is established by analyzing four fundamental requirements of protection relay and the concept of long and short-term outage. Then, random variables used to form fault scenarios are determined according to different protection configurations. Monte Carlo method is used to generate random fault scenarios. Then, energy loss of different schemes in different fault scenarios can be calculated. Finally, the average energy loss of each protection scheme is calculated, and the scheme with the smallest average energy loss is selected as the best one. The validity of this method is verified by two cases of distribution network protection with different setting values and hybrid lines with or without automatic reclosing.
System-side Harmonic Impedance Estimation Based on Modified Independent Random Vectors
WU Yayue, XU Fangwei, ZHANG Weijun, SHU Qin
2019, 43(20): 146-152.DOI: 10.7500/AEPS20190315010
[Abstract](53)[PDF 1.34 M](24)
With the access of new energy and power electronic equipment, there are a large number of harmonic sources in the power grid, which makes harmonic pollution and harmonic resonance problems more serious. Since background harmonic fluctuations become larger and the customer side is usually equipped with filter devices, the harmonic impedance of customer side is not much larger than that of the system side. Accurate estimation of system-side harmonic impedance is of great significance for harmonic control and harmonic resonance analysis. However, the existing methods for estimating harmonic impedance usually assume that the background harmonic is stable or harmonic impedance of customer side is much larger than that of the system side, which are not always satisfied in practical cases and lead to larger estimation error. Therefore, based on the independent random vector method, this paper proposes a method for estimating the harmonic impedance based on the weak correlation between harmonic voltage and harmonic current at different time intervals. By analyzing the correlation of harmonic voltage and harmonic current measured at the point of common coupling(PCC), the threshold of the normalized correlation coefficient is set to screen out the weak correlation period, in which the correlation of the harmonic current of system side in different time intervals is always weak. Thus, the harmonic impedance of system side can be obtained. Compared with the existing methods, the proposed method requires less data and can significantly eliminate the negative effects of the background harmonic fluctuation and impedance ratio of two sides, and has a wider application range. Simulation and field cases are conducted to verify the effectiveness of the proposed method.
Amplitude-Frequency Characteristic Analysis of Harmonic/Inter-harmonic of Grid-connected DFIG Based on Pulse Width Modulation
TAO Shun, LIU Yunbo, ZHAO Lei, LIAO Kunyu
2019, 43(20): 153-161.DOI: 10.7500/AEPS20190125002
[Abstract](63)[PDF 1.50 M](32)
The grid-connected doubly-fed induction generator(DFIG)system is usually accompanied with the harmonic/inter-harmonic emission problem. By using the ideal impedance model of DFIG and the switching function of pulse width modulation(PWM), this paper deduces an analytical expression of harmonic/inter-harmonic voltage caused by back-to-back dual PWM convertor. Taking the filter structure and generator asynchronous characteristic into account, this paper also derives the amplitude and frequency formula for harmonic/inter-harmonic current with the DC voltage as input. Then the mechanism of modulation harmonic/inter-harmonic produced in the back-to-back convertor of DFIG is revealed. For the actual operation scenario of DFIG, the typical emission characteristics of harmonic/inter-harmonic with background harmonics are obtained. The PSCAD simulation and the analysis results based on the measured data of an actual wind farm show the accuracy of derived expressions and mechanism characteristic analysis.
Credibility Evaluation of Time Delay Measurement of Transmission for Sample Value in Mixed Network
ZHOU Hualiang, ZHENG Yuping, XU Jiansong, LI Youjun
2019, 43(20): 162-169.DOI: 10.7500/AEPS20180920001
[Abstract](54)[PDF 2.23 M](30)
The certainty and accuracy of transmission time delay of analog sample value(SV)in network sampling and tripping are key factors for the reliable operation of the system in smart substation. A real-time measurement and compensation method for transmission delay of realizing SV data transmission based on message is gradually accepted by the majority, and applied to the 3-in-1 network in smart substation and dedicated network for outdoor installation protections. In this paper, the principle and implementation of the time delay measurement method for SV message transmission are described first, the credibility and its influence of proposed method in related parts of realizing accurate measurement of transmission delay are analyzed in detail. Then, an online credibility evaluation method based on the combination values of the total link delay and the total link delay error is proposed according to the delay measurements for strong correlation between messages and SV data and how to select the value of engineering threshold is put forward. At last, the effectiveness and reliability of the scheme are verified by selecting the special test analysis and practical application of outdoor protection dedicated network.
Single-line Diagram of Substation Centralized Distribution Network Part Three Beautifying Layout Calculation
QIU Chengfeng, ZHANG Jianmin, LIU Lifeng, ZHANG Yongjian, HUANG Jianping, ZHANG Jianguang
2019, 43(20): 170-175.DOI: 10.7500/AEPS20180827011
[Abstract](73)[PDF 2.14 M](35)
The previous two papers in this series have proposed a data-diagram model and an initial layout auto-generation algorithm for single-line diagram of substation centralized distribution network(SCDN), and this paper will focus on beautifying and optimization calculation for the initial layout single-line diagram. The line intersection number of the initial layout single-line diagram has been greatly minimized even to zero, however, the iterative calculation of force-directed algorithm will yield many line intersections caused by the lower class line branches over cross the upper class line sections, therefore, a new force called ‘inertia force' on the lower class ‘node cluster' to keep their nodes as a cluster having a certain inertia force to avoid their nodes separating and splitting caused by outside forces. An optimal parameter setting approach for force-directed is provided to minimize the line intersections through optimizing the parameters of different forces consisting of attraction, impulsions between node to node, node to edge and edge to edge, and gravity force, inertia force, etc. Generic algorithm(GA)is used to solve this optimization problem. 10 kV SCDNs of five actual 110 kV substations are testified, the results show that the proposed method can generate a single-line diagram with high identification of connection performance.
Egineering Application
Comprehensive Analysis Platform of Load Characteristics Based on Extendable and Interactive Design
WANG Shouxiang, DENG Xinyu, CHEN Haiwen, GUO Luyang, ZHI Yawei, LI Zhixin
2019, 43(20): 176-182.DOI: 10.7500/AEPS20190126004
[Abstract](120)[PDF 1.36 M](40)
Load characteristic analysis based on multi-source data can improve the intelligence level of power distribution and utilization, and provide guidance for socio-demographic information identification, load monitoring and demand response analysis. In order to increase the convenience of the development of the above functions and improve the comprehensive analysis ability of power distribution, an interactive comprehensive analysis platform with load characteristic analysis function as the core, which can expand advanced functions, is built. The platform adopts Browser/Server architecture, which can cross platforms and adapt multiple terminals to realize one-time design and global use. At the same time, Django framework is used to realize extensible design, and a variety of algorithms and data are integrated to provide convenience for analysis. It realizes interactive design based on HTML5 technology and improves the visualization level of the platform under the background of big data through Canvas rendering scheme. The effectiveness and superiority of the comprehensive analysis platform are verified by a test case of day-ahead load forecasting.
Wide-area Coordinated Control and Benefit Assignment Strategy of Clustering Wind-Energy Storage Integrated System
LU Qiuyu, LUO Shuxin, HU Wei, YANG Yinguo
2019, 43(20): 183-191.DOI: 10.7500/AEPS20181223001
[Abstract](98)[PDF 1.49 M](32)
To solve the coordinated problem for multiple wind-energy storage integrated systems, this paper proposes the clustering wide-area coordinated control frame for multiple wind-energy storage integrated systems. The multi-pattern optimized dispatching model considering the spatial-temporal correlation of wind power is constructed. Furthermore, a strategy based on cooperative game theory is proposed to allocate the cluster benefits. Simulation verifications of the proposed model and strategy are made by using actual wind power data. Simulation result indicates that the wide-area coordinated control can maximize the profit of the cluster, improve the controllability of wind power and operation efficiency of energy storage. The assignment strategy of cluster benefit based on cooperative game theory can coordinate the benefits of the individual and the cluster, which can encourage the wind-energy storage system to actively participate in the cluster control.
Discussion on Several Problems of Earthing Fault Protection in Distribution Network
XU Bingyin, XUE Yongduan, FENG Guang, WANG Chao
2019, 43(20): 1-7.DOI: 10.7500/AEPS20190420007
[Abstract](202)[PDF 1.50 M](99)
Power grid companies in China propose to quickly and closely isolate the earthing fault of distribution networks to reduce electric shock and large-scale blackout. However, there are great controversies on different earthing modes and the advantages and disadvantages of earthing fault protection methods for medium-voltage distribution network, and no consensus has been reached, which is not conducive to the formation of an optimized earthing fault disposal method. In this paper, experiences at home and abroad are summarized. Technical characteristics of different earthing modes and their earthing fault protection methods are compared. It is pointed out that the earthing mode will affect the detection standard of earthing fault and the statistical result of protection accuracy. The problems existing in the conversion of low current grounding system to low resistance grounding, arc suppression coil parallel low resistance grounding and active intervention arc suppression are analyzed. Transient earthing protection technology and its application are introduced. For different types of distribution network, the selection of earthing mode and earthing protection method is suggested.

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