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

Volume 43,Issue 13,2019 Table of Contents

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Design Ideas of Robotic Dispatcher for Power Grid
ZHANG Xiaohua, FENG Changyou, WANG Yongming, WANG Yiyu, WANG Jing, DENG Yong, WANG Yang, HAN Ye
2019, 43(13): 1-8.DOI: 10.7500/AEPS20180716001
[Abstract](643)[PDF 3.25 M](389)
Abstract:
As the scale of power grid of China continues to expand and the operation characteristics become increasingly complex, the complexity of dispatching and control business of power grid and the burden of dispatchers are increasing. According to the real-time dispatching and control business of power grid, this paper designs an overall architecture of robotic dispatcher for power grid. The design ideas of five functional modules such as intelligent learning, intelligent decision-making, intelligent monitoring, intelligent execution and intelligent interaction are elaborated. Then the corresponding key technologies are described. The six types of application scenarios of dispatching and control are given.
Ubiquitous Electric Power Internet of Things
Explanation and Prospect of Ubiquitous Electric Power Internet of Things
YANG Ting, ZHAI Feng, ZHAO Yingjie, PEN Haibo
2019, 43(13): 9-20.DOI: 10.7500/AEPS20190418015
[Abstract](809)[PDF 1.67 M](478)
Abstract:
Energy Internet is a new type of ecological energy system regarding electric energy as the center, realizing multi-energy coordination, consumption synergy, centralized or distributed coordination, and extensive participation of the public, in which the main performance is the strong integration of the smart grid and ubiquitous electric power internet of things. But the ubiquitous electric power internet of things is just in its infancy and is a key step in the construction of Energy Internet. The construction of ubiquitous electric power internet of things has obvious positive significance for improving user experience, improving the operation level of the power grid, promoting new energy consumption and cultivating emerging businesses. This paper summarizes the overview of the internet of things, the characteristics of ubiquitous electric power internet of things, the key technologies supporting ubiquitous power internet of things and the typical application scenarios. Finally, the challenges in the development of ubiquitous power internet of things is analyzed and prospected.
Basic Research
Oscillation Analysis Based on Trajectory Modes Decoupled in Space and Mode-energy-sequence Part Two Algorithm and Application
LIU Qinglong, XUE Yusheng, CHEN Guoping
2019, 43(13): 21-28.DOI: 10.7500/AEPS20190430034
[Abstract](455)[PDF 1.38 M](213)
Abstract:
This paper analyzes the time evolution of oscillation energy based on the trajectory modes decoupled in state space and the swings divided in time domain. The trajectory of multi-machine system, which is non-harmonic oscillation, can be mapped into a series of trajectories for time-varying image system through the complementary-cluster center-of-inertial relative-motion(CCCOI-RM)transform, so the oscillation behavior of the multi-machine system is described by the oscillation energy variation of the successive swing. Besides, the non-conservative can be quantified through analyzing the time-space variation of the oscillation energy on the force-position plane. In this paper, the kinetic energy at the dynamic center point(DCP)and the potential energy at the far end point(FEP)are both used to reflect the oscillation energy in the past half swing. Therefore, the sequence of them can reflect the time-varying characteristic of the spatial oscillation mode. After that, through theoretical analysis and numerical simulation, the consistency between the trajectory swing energy sequence and the eigenvalue system is proved when they are used to describe the oscillation behavior of Hamilton one machine infinite-bus(H-OMIB), but the trajectory swing energy sequence can also be used to overcome many defects of the eigenvalue in the non H-OMIB or general multi-machine system.
Optimal Operation Model of Concentrating Solar Power Units Considering Startup Heat Constraints
FENG Chenjia, SHAO Chengcheng, WANG Yanan, SUN Pei, HAN Wei, WANG Xifan
2019, 43(13): 29-35.DOI: 10.7500/AEPS20181026004
[Abstract](263)[PDF 1.71 M](164)
Abstract:
Concentrating solar power(CSP)generation system can well cope with the randomness and intermittence of solar power, which provides a new approach to exploit large-scale renewable energy. There are no unit startup constraints in the existing model, which may lead to infeasible operation schedule. For this problem, this paper analyzes the heat accumulation process during startup of CSP units and develops a CSP operation model considering startup heat constraints. It can describe the operation characteristics of CSP units more precisely. The optimal operation of CSP units is also studied based on the above model. Example analysis is conducted on the modified IEEE-RTS79 system. The results show that the proposed model is correct and effective, and can avoid the occurrence of unfeasible startup schemes. Also, further sensitivity analysis reveals the benefits of CSP units in reducing production costs and promoting accommodation of other renewable energy and its influencing factors.
Distribution Model of Day-ahead Photovoltaic Power Forecasting Error Based on Numerical Characteristic Clustering
ZHAO Shuqiang, ZHANG Tingting, LI Zhiwei, LI Dongxu, XU Xiaoyan, LIU Jinshan
2019, 43(13): 36-45.DOI: 10.7500/AEPS20180405002
[Abstract](272)[PDF 1.51 M](131)
Abstract:
The forecasting error of photovoltaic(PV)output is difficult to avoid and cannot be ignored. The accurate description of the forecasting error distribution is beneficial to the optimal dispatch and stable operation of the power system. The correlation between the forecasting error distribution and influencing factors is analyzed, and a probabilistic model of the PV output forecasting error based on numerical characteristic clustering is proposed. The whole level of forecasting errors will be classified through the fuzzy C-means clustering and the classification on the output forecasting will be conducted according to its numerical characteristics. A general Gauss mixed model available to estimate error distribution is established. Considering the influences of meteorological factors and numerical characteristics on forecasting errors, the model could estimate forecasting errors at different times and produce the confidence interval of error distribution. At the same time, the proposed model is free from the influences brought by different forecasting algorithms and the geographic information of PV power station. Based on the historical data of PV systems in Belgium and Northwest China, analysis results show that the skewness, multi-peak and kurtosis diversity of PV power forecasting error distribution can be described by the proposed model more accurately compared with other distribution models, which can be used to describe the forecasting error distribution of day-ahead PV power in different situations.
Optimal Operation Control Strategy of Microgrid Based on Double-lead Carbon Battery Energy Storage System
YAN Gangui, LI Hongbo, DUAN Shuangming, ZHU Wei, LI Junhui, LIU Ying
2019, 43(13): 46-53.DOI: 10.7500/AEPS20181129005
[Abstract](288)[PDF 1.44 M](157)
Abstract:
Due to the fact that power fluctuation caused by wind power, photovoltaics and electric vehicle charging threatens the safe operation of microgrid, based on the relationship between electric throughput and the depth of charging and discharging in the whole life of lead carbon battery, an optimization strategy for path switching of charging and discharging mode controlled by operation balance index of double battery energy storage system(DBESS)is proposed, and a charging and discharging control strategy of DBESS based on the best depth of charging and discharging of lead carbon battery is proposed. Calculation results of the strategy proposed and traditional strategy are compared by using actual operational data of wind power, photovoltaics, double lead carbon battery energy storage system, lithium-ion electric vehicle charging and regular load. Results show that the proposed strategy can not only optimize the path of charging and discharging mode, but also break the restriction of state of charge consistency between beginning and end of the charging and discharging process in the DBESS, so that the available capacity can be increased to the most extent and the flexibility of the use of battery energy storage system can be enhanced. The rationality and validity of the proposed strategy are finally verified by charging and discharging saturability index and stability index of DBESS.
Partitioning Method of Virtual Microgrid Based on Electrical Coupling Strength
WU Chunchao, XUE Fei, XU Xiaotong, LU Shaofeng, JIANG Lin, LI Gang
2019, 43(13): 54-60.DOI: 10.7500/AEPS20180601004
[Abstract](294)[PDF 1.48 M](133)
Abstract:
With the fast development in the research of smart grid and Energy Internet, more and more distributed renewable energy and energy storage devices are connected into distribution networks, intelligent development of distribution network has become an inevitable trend. It is a big challenge for large-scale conventional distribution networks to be consistent with the requirements of free, equal and flexible interaction. Virtual microgrids with high internal convergence are proposed based on electrical coupling strength, which is partitioned from conventional power distribution networks. Furthermore, an implementation framework of virtual microgrids based on extended cyber, physical and socioeconomic is put forward, three-stage research problems of boundary division, resource optimization deployment and collaborative capability management are introduced. According to the first problem, by defining the electrical coupling strength, the classical Newman fast partitioning algorithm is upgraded in complicated network to realize the automatic optimization of boundary in virtual microgrids. Through case studies, the proposed algorithm is verified to be reasonable and efficient.
Robust State Estimation of Electric-Gas Integrated Energy System Based on Weighted Least Absolute Value
CHEN Yanbo, ZHENG Shunlin, YANG Ning, YANG Xiaonan, LIU Kaicheng
2019, 43(13): 61-70.DOI: 10.7500/AEPS20180428003
[Abstract](289)[PDF 1.43 M](103)
Abstract:
The electric-gas integrated energy system has been paid more and more attention at home and abroad because of the ability of large-scale storage of natural gas and the technological support of power to gas(P2G). In order to achieve the comprehensive, real-time and accurate perception of the electric-gas integrated energy system, the state estimation(SE)of integrated energy system(IES-SE)coupling natural gas and electricity is needed. IES-SE depends on the modeling of electric-gas coupling model, branches containing compressor and electric-gas joint estimation. As for coupling model, both gas turbine and P2G unit are utilized to achieve the two-way transformation of energy flow. As for modeling of branches containing compressor, a new constraint model is proposed, which not only considers the constraints of compressor elements on gas pressure, but also the consume of gas by gas turbine. On this basis, the weighted least absolute value SE model of the electric-gas integrated energy system is constructed, and its solution method is given. Finally, the results of simulation prove the validity of the proposed models of coupling model, branches containing compressor and IES-SE.
State Estimation for Active Distribution Systems Incorporating Photovoltaic Plant and Battery Energy Storage System
FANG Zhi, SONG Shaojian, LIN Yuzhang, LIN Xiaofeng, CHENG Gang
2019, 43(13): 71-79.DOI: 10.7500/AEPS20181114002
[Abstract](261)[PDF 1.36 M](130)
Abstract:
The large-scale integration of distributed energy resources with intermittent and stochastic volatility, the random charging and discharging of energy storage system and electric vehicles, and measurement errors of the intelligent measuring devices make the situational awareness of active distribution systems face some challenges. Considering the influencing factors such as the solar irradiance, the temperature, and the state of charge(SOC)of batteries, a state estimation model for the active distribution systems is developed including integrated photovoltaic power generation systems, the distribution network, and battery energy storage systems. Firstly, based on the photovoltaic five-parameter model and the battery internal resistance model, the measurement functions and the Jacobian matrix of the photovoltaic systems and battery energy storage systems are derived. Then, combined with the state estimation model of the distribution network, the electrical quantity and non-electrical quantity are uniformly standardized, and the state estimation and bad data processing of the active distribution systems are performed. Finally, the simulation is carried out in IEEE 33-node system. The simulation results show that, compared with the conventional model which only takes the photovoltaic system and the battery energy storage system as PQ nodes, the proposed method significantly expands the scopes and capabilities of state estimation and bad data processing in the photovoltaic system and battery energy storage system, and improves the accuracy of the state estimation of the distribution network.
Topology Similarity Analysis Method for Distribution Network Based on Hierarchical Clustering of Macroscopic and Microscopic Features
LIN Junhao, ZHANG Yan, ZHU Jinzhou, ZHAO Teng, SU Yun
2019, 43(13): 80-88.DOI: 10.7500/AEPS20181017006
[Abstract](247)[PDF 1.60 M](102)
Abstract:
A topology similarity analysis method for distribution network based on hierarchical clustering of macroscopic and microscopic topology features is proposed. Firstly, the index set covering macroscopic and microscopic topology features is constructed as a basis for topology similarity analysis, including network community characteristics and node degree correlation indices at the macroscopic level, and line power transmission performance and load distribution density indices at the microscopic level. Since it is difficult for traditional topology similarity methods to make fine-grained analysis on microscopic topology features with different numbers of variables, a microscopic topology feature description method based on kernel density estimation and a microscopic feature similarity measurement method based on Kullback-Leibler divergence is proposed. The improved spectral clustering algorithm based on coefficient of variation is used for hierarchical clustering of macroscopic and microscopic topology feature sets, to realize topology similarity analysis for distribution network. Case study shows that the proposed topology similarity analysis method of distribution network is superior to the traditional method in the ability of representing structural characteristics of distribution networks and the effect of similarity analysis.
Staged Selection of Site and Type for Distribution Terminals and Networking Strategy Considering Influence of Communication Reliability
HU Zhihao, TONG Ning, LIU Qi, ZHENG Yuchao, LIN Xiangning, LI Zhengtian
2019, 43(13): 89-97.DOI: 10.7500/AEPS20180620013
[Abstract](234)[PDF 1.81 M](139)
Abstract:
For the selection of site and type of power distribution terminals, the 9-state transition model considering communication link failure is firstly proposed. Secondly, the link failure of different communication networking modes of power distribution terminals without tele-control function and power distribution terminals with tele-control function is considered. Under the condition of economic loss caused by error/rejection failure, a calculation method of integrated power outage loss considering the influence of communication reliability is proposed, and together with the construction cost of distribution terminal, the objective function is used for the selection. Then, combined with the theory of node importance and considering the dual constraints of power supply reliability and investment cost, a staged selection strategy of site and type for power distribution terminals is proposed. Results of the example show that the proposed staged site and type selection planning method can obtain a feasible solution that satisfies the constraints stably and reliably. In the scenario that the traditional intelligent algorithm based integrated planning method falls into the local optimal solution or even unable to obtain the feasible solution, the proposed staged planning method can still guarantee the quality of the solution.
Decentralization Configuration Method of Power Resources Based on User Preference
SHE Wei, YANG Xiaoyu, TIAN Zhao, MA Jianhong, LI Zhengze, LIU Wei
2019, 43(13): 98-104.DOI: 10.7500/AEPS20180731015
[Abstract](256)[PDF 1.52 M](101)
Abstract:
To solve at the security problems of large-scale and high-frequency energy and information flow in the process of multi-user transmission and interaction, this paper proposes a decentralization configuration method of power resources based on user preference. Firstly, the nodes in the energy market are divided into two parts: energy nodes and energy block agent router. Then, the preferences in energy supply and demand are classified into three categories: environment-friendly, transport resource-saving and cost-effective according to historical energy supply habits. A kind of energy information matching algorithm and comprehensive evaluation function are proposed to meet the optimal configuration of power resources in multi-user environment. The simulation results show that the model can improve the consumption ratio of clean energy in market transactions, promote the energy near consumption and improve the resource allocation ability of the power grid.
Analysis and Calculation of Loss Characteristics for Hexagonal Modular Multilevel AC/AC Converter
ZHANG Chong, LI Kuanhong, ZHANG Xuan, JIANG Daozhuo, LIANG Yiqiao
2019, 43(13): 105-113.DOI: 10.7500/AEPS20180620005
[Abstract](237)[PDF 1.35 M](113)
Abstract:
The detailed analysis of loss characteristics for converter is of great importance for system design and cooling device selection. This paper analyzes and calculates the loss distribution of submodule and the total loss of converter based on the working characteristics of full bridge submodules in hexagonal modular multilevel AC/AC converter(Hexverter). Firstly, the operation principle of Hexverter is briefly introduced and simulated. Secondly, the on-state and switching characteristics of insulated gate bipolar translator(IGBT)and freewheel diode are established by fitting the data of IGBT module. The working conditions of submodule are analyzed in detail. According to the output characteristics of full bridge submodule, the analytical expressions of conduction range and the time of each device are derived, respectively. Then the theoretical analysis expressions of conduction loss and switching loss are obtained. Finally, the loss of the converter is quantificationally analyzed in 10 kV system, the loss distribution of different submodules is calculated, and the losses of Hexverter in different working conditions are calculated. The results show that the loss distribution in full bridge submodule is symmetrical, and the loss of each submodule in one branch is not the same. Additionally, the loss distribution of submodules and the total loss of the converter are obviously different, especially in various working conditions of different capacities and power factors.
Application Research
Flexible Planning Methods for Distribution Network with Uncertainties During Development
ZHANG Man, WANG Zhuding, WANG Jingyu, ZHU Dongpo
2019, 43(13): 114-123.DOI: 10.7500/AEPS20181119001
[Abstract](283)[PDF 1.49 M](151)
Abstract:
With the rapid development of urbanization in China, there are more and more uncertain factors in distribution network planning. Therefore, a new set of ideas, models and methods of flexible planning for distribution networks is proposed, which is related with substations, channels, networking forms and their transition of medium voltage network structures. Firstly, it is pointed out that all main channels should be reserved for the convenient access of new nearby loads and substations. Secondly, for the determination of substation site reservation schemes, the corresponding optimization method is put forward based on multi-scenario probabilities, and a decision-making method is proposed based on the break-even analysis. Then, the advantages of a ring type networking form are elaborated for flexible planning, and the optimization model and corresponding heuristic solution method are proposed to make a choice between a mesh-type structure and a ring-type structure. It is also proposed that a planning priority is given to the main trunk lines of a medium voltage distribution network. Finally, based on the estimated table of farthest power supply distances, some flexible transition schemes of networking forms are proposed by adjusting the power supply ranges. The effectiveness and applicability of the proposed flexible planning methods are verified through numerical examples.
Traveling Wave Fault Location Technology for Hybrid Lines in Distribution Network Based on Disturbance Signal Injection at Busbar
QI Zheng, ZHUANG Shuyi, HE Xiqi, HUANG Zhezhu
2019, 43(13): 124-130.DOI: 10.7500/AEPS20180726009
[Abstract](242)[PDF 1.35 M](89)
Abstract:
The technology of disturbance signal injection at the busbar of medium voltage distribution network and cooperating with fault indicators to locate fault section has been used more and more widely. Disturbance signal sources at busbar can provide traveling wave signals, which provides the possibility of fault location. This paper proposes a traveling wave fault location method based on disturbance signal injection at busbar. If a permanent single-phase grounding fault occurs, the non-fault phase is switched to the ground via a resistance. Then an appropriate aerial mode component is selected according to the principle of traveling wave transmission and the fault distance can be calculated by the time difference between the arrival time of this component and the injection time of disturbance signal. Meanwhile, a solution to calculate the fault distance in the hybrid overhead-cable lines with branches is proposed. The least-square estimation is utilized to effectively merge multiple location results in order to improve the accuracy of fault location. The accuracy of the proposed technology is verified by the simulation and field test results.
Substation Information Based Method for Preventing Mal-operation of Zero-sequence Directional Protection on Multi-circuit Transmission Lines on the Same Tower
DAI Feiyang, WANG Xingguo, YANG Guosheng, ZHOU Zexin
2019, 43(13): 131-138.DOI: 10.7500/AEPS20180825004
[Abstract](236)[PDF 1.35 M](77)
Abstract:
In case of open-phase operation or asymmetric longitudinal fault occurring on one line of the multi-circuit transmission lines on the same tower, the zero-sequence directional protection of healthy lines with the same voltage on the same tower may mal-operate due to the zero-sequence voltage compensation. Zero-sequence voltage induced between the lines on the same tower with mixed voltages may also cause mal-operation. The electrical characteristics of asymmetric longitudinal faults and open-phase operation and the specific mechanism leading to mal-operation of zero sequence directional protection are analyzed. The influence of various factors on the process of mal-operation and the solution are discussed. A method for preventing mal-operation by extracting the states of transmission lines based on substation information is proposed. For multi-circuit transmission lines with the same voltage on the same tower, the method for preventing mal-operation by calculating the cross point of zero-sequence voltage and reversely compensating zero-sequence voltage is proposed. For multi-circuit transmission lines on the same tower with the mixed voltages, the method of identifying the failure characteristics of the lines based on the substation information and automatically blocking the zero-sequence directional protection is proposed. Real-time digital simulator(RTDS)is used to simulate the electrical characteristics of healthy lines and the mal-operation process when an asymmetric longitudinal/latitudinal fault occurs on multi-circuit transmission lines on the same tower under different work conditions. The effectiveness of the proposed method for preventing mal-operation is verified.
Live-action Substitution Based Field Performance Test Scheme for UHVDC Protection System
KONG Xiangping, LI Peng, RUAN Siye, CUI Yu, LUO Qiang, GAO Lei, WANG Ye
2019, 43(13): 139-146.DOI: 10.7500/AEPS20180411006
[Abstract](228)[PDF 3.21 M](72)
Abstract:
There is no effective method to test the functions and performances of ultra-high voltage direct current(UHVDC)protection system in debugging or operation and maintence stage of engineering field. The live-action substitution based field performance test scheme for UHVDC protection system is proposed. Moreover, the corresponding test device of UHVDC protection system is developed. The various hardware interfaces of the UHVDC protection test device are employed to lively substitute the hardware environment of the tested UHVDC protection system. The key technologies including synchronous output of multi-source signals, output of digital signals with multi-protocol, distributed multi-device synchronization and replaying of fault recording data are developed to ensure the live-action substitution of the operational environment of tested UHVDC protection system. The field application indicates that the proposed live-action substitution based test scheme for UHVDC protection system can effectively test the functions and performances for UHVDC protection system.
Generic Message Source and Flow Calculation Model for Communication Network in Smart Substation
ZHANG Jianmin, ZHANG Jiayu, NI Ming, LI Kangyi, JIN Naizheng, YANG Caiming
2019, 43(13): 147-155.DOI: 10.7500/AEPS20180912008
[Abstract](245)[PDF 1.45 M](85)
Abstract:
The model used to predict the message flow of communication network in various scenarios is very important for smart substation. A generic source model based on cyber physical fusion is firstly proposed, including spontaneous message model of intelligent electronic device excited by the state of primary power system in secondary side, source model of physical fault in cyber devices and parasitic denial of service(DoS)attack, which establishes an integrated spontaneous message model of cyber devices. Then, based on the network calculus and transmission path of junction flow method, the distribution matrix definition and calculus method of smart grid information flow based on the generic message source are put forward, which forms a clear and detailed quantitative analysis and calculation process. Finally, some typical scenarios, such as cyber device failure in process layer, DoS attack and primary circuit faults in small or large operation modes, are validated as theoretical calculation examples, and OPNET simulation results show the effectiveness of the proposed method.
Wide-area Data Acquisition Scheme Based on Power Dispatching Data Network
DU Peng, YAN Liang, GAO Baocheng, WANG Xuetao, LI Dantong, MEI Zheng
2019, 43(13): 156-161.DOI: 10.7500/AEPS20180608006
[Abstract](285)[PDF 1.34 M](140)
Abstract:
In the smart grid, the requirement for business collaboration and exchange of data between multiple grid dispatching and control systems is increasing. But the problems such as prolonged and difficult maintenance exist in the practice of data forwarding based on protocol transmission method between multiple grid dispatching and control systems. There is a pressing need for a more efficient and convenient wide-area real-time data transmission mode. On this basis, the limitations of current data acquisition mode are analyzed. A wide-area data acquisition scheme based on power dispatching data network is proposed. The wide-area data acquisition frame and network structure are discussed. The data subscription mechanism, data issuing technology and data acquisition agent method in the wide-area environment are deeply studied. After experimental verification, the wide-area data acquisition can enhance the connection between multiple grid dispatching and control systems, provide more efficient wide-area data interactive means, and improve data transmission efficiency and system usability.
Object Detection Method for Aerial Inspection Image Based on Region-based Fully Convolutional Network
LIU Siyan, WANG Bo, GAO Kunlun, WANG Yue, GAO Chang, CHEN Jiangqi
2019, 43(13): 162-168.DOI: 10.7500/AEPS20180921005
[Abstract](234)[PDF 1.33 M](83)
Abstract:
Aerial inspection is one of the main methods of transmission line inspection. In consideration of inefficient of aerial inspection mode and subjective factors of inspectors, there is an urgent need for intelligent detection algorithm to locate and identify the faults in inspection pictures of transmission line. As a possible solution, object detection technology of aerial inspection imagge based on deep learning has attracted extensive attention. An object detection method of aerial inspection image utilizing region-based fully convolutional network(R-FCN)is proposed. Online hard example mining(OHEM), sample adjusting and soft non-maximum suppression(Soft-NMS)are adopted to improve the performance of the proposed algorithm. The experiment results show that the proposed method has obvious advantages on accurate target location, high average precision, and simultaneous detection of target species by single-model.
Development of Virtualization-technology-based Cluster Measurement and Control Device at Bay Level in Smart Substation
WANG Yongfu, ZHANG Fangzheng, WANG Yafei, ZHANG Yang, ZHAO Shuo, LIU Yiqing
2019, 43(13): 169-176.DOI: 10.7500/AEPS20181221007
[Abstract](257)[PDF 1.66 M](102)
Abstract:
Measurement and control devices are usually configured by bays in smart substations. This kind of configuration may cause several problems, such as numerous facilities and lack of alternative devices. To solve these problems, a novel cluster measurement and control system for bay level is studied and the cluster measurement and control device is developed. This device can break the restriction of disposing measurement and control device by bays and achieve the goal of monitoring the whole substation by a group of cluster devices. Through the dynamic migration of measurement and control functions, each cluster measurement and control device can be backed up each other. This paper elaborates the functions of the cluster measurement and control system and device, the framework of software and hardware, and crucial technology, respectively. The results of type experiment and field trial show that the performance of this cluster measurement and control system and device can completely satisfy the requirements of monitoring for smart substation. The management and maintenance patterns of cluster measurement and control devices stays compatible with existing smart substation monitoring systems.
Egineering Application
Damping Control Method of Subsynchronous Oscillation for Direct Drive Wind Turbine Generator and Its Adaptability
ZHOU Peipeng, SONG Ruihua, LI Guangfan, DU Ning, CHANG Xiqiang, GUO Xiaolong
2019, 43(13): 177-184.DOI: 10.7500/AEPS20180922003
[Abstract](276)[PDF 1.68 M](117)
Abstract:
The subsynchronous oscillations caused by wind power fluctuations have characteristics of variable oscillation frequency, abundant related dynamic devices and complicated influencing factors, the current damping control devices are difficult to realize the effective mitigation of this phenomenon, it is necessary to study the applicable additional damping control methods. The characteristic equations and transfer functions are deduced for integrated power systems with direct drive permanent magnet synchronous generator(PMSG)based wind turbine generators by linearization methods, and frequency response characteristics of the system under different conditions are obtained. A parameter design method for subsynchronous oscillation damping controller of wind turbine generator based on Nyquist stability criterion, and a parameter optimization method based on particle swarm optimization are proposed. By eigenvalue analysis and time domain simulation, the mitigation effect of damping controller on subsynchronous oscillation is analyzed. Results show that the designed damping controller based on the above method is adaptable under various operating conditions.
Analysis on Impact of Enhanced Governor on Ultra-low Frequency Oscillation in Yunnan Power Grid of China
HE Yue, ZHANG Yong, CHEN Yiping, MO Weike
2019, 43(13): 185-190.DOI: 10.7500/AEPS20190123001
[Abstract](285)[PDF 1.29 M](137)
Abstract:
Enhanced governors are adopted in some hydroelectric units in Yunnan power grid, which causes the ultra-low frequency oscillation and threatens the frequency stability of power grid seriously. In order to reveal why the enhanced governors of hydroelectric units affect the frequency of Yunnan power grid of China, the theoretic calculation and time-domain simulation are conducted on dynamic behaviors when the system frequency difference across the dead zone of primary frequency regulation from different directions. It is demonstrated that the enhanced governor does not have a stable equilibrium point near the dead zone of primary frequency regulation of hydroelectric generator, and when the system frequency difference slowly passes back to the dead zone, a phase lag of about 90 degrees is introduced in ultra-low frequency band, thus reducing the safe and stable margin of the system frequency. Finally, the eigenvalues of a single-machine system including hydro turbine, governor and generator models are calculated with the aid of small disturbance analysis tools. Through the comparative simulation, it is shown that the enhanced governor not only has similar negative damping effect with the water hammer in ultra-low band, but also is the one of the disturbance sources of ultra-low frequency oscillation, which keeps ultra-low frequency oscillation continuous and unable to attenuate.

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