Master Station Research Articles

An Improved Master-Slave Control Strategy for Automatic DC Voltage Control Under the Master Station Failure in MTDC System

The master-slave (MS) control is often used in multi-terminal direct current (MTDC) system due to its stable dc voltage control and precise power regulation. However, the MS switching, which aims to maintain dc voltage control under the master station failure, relies heavily on the high-speed communication between the power dispatch center and each station. Some methods in existing works are proposed to address the high communication dependence, at the cost of steady-state control performance. In this article, an improved MS control including five-state control process is proposed to realize the automatic MS switching without communication participation. Based on logic judgment, the multilayer dc voltage clamping mechanism is created to enhance the redundancy of the dc voltage control, and a reasonable dc voltage recovery process is included to eliminate the dc voltage deviation caused by the master station failure. Furthermore, the power and dc voltage hybrid controller are developed to improve the dynamic performance of each station during the MS switching. Simulation and experimental results demonstrate the effectiveness and advantages of proposed method.

A divide-and-conquer method for compression and reconstruction of smart meter data

As smart grid sensors, smart meters generate abundant valuable data, laying the foundation for data-driven applications. However, the data collection brings huge communication pressure to electric utilities. In this context, considering that different types of devices have different power consumption patterns, and different types of data compression methods have their own applicable scenarios, we propose a divide-and-conquer method for compression and reconstruction of smart meter data. First, based on algorithm of voice activity detection (VAD), a load power fluctuation segment location method is proposed, which is combined with load event detection method to divide the load data into the event segments, fluctuation segments, and steady-state segments. Then, for the fluctuation segments, a cloud-device collaboration adaptive strategy based on the compressive sensing (CS) theory is designed, in which the sparse basis and measurement matrix are updated accordingly to ensure the high reconstruction accuracy in different scenarios. For the steady-state segments, a data compression method based on the improved symbolic aggregation approximation (SAX) is established, in which the dividing rectangle (DIRECT) algorithm and the irregular time partitioning method are combined to reduce the data volume for transmission without losing important information. For the event segments, the original data values are retained since the event power curves are relatively more complex and short duration. Finally, the received compressed data are reconstructed into the original power time series data in the master station on cloud to support advanced data analytics. Comparative experiments are conducted on the private and public datasets of 12 households in North America and China. The results show that our method has higher data reconstruction accuracy and compression efficiency compared to the existing methods.

Research on Working Mode of Intelligent Terminal of Distribution Automation Based on Public Wireless Communication Network

Targeting the situation that the wireless communication terminal commonly exists in the pilot project of distribution automation has an unstable power supply under extreme conditions, this paper proposes a non-real-time online working mode that is different from the traditional real-time online working mode. The switching method of the two working modes was designed, and the comparison and analysis between the two working modes were performed in terms of the timeliness of event active reporting, communication flow, the impact on the processing mechanism of the master station system and the impact on the working duration of the power supply. The results show that the average power consumption of the wireless communication terminal under the non-real-time working mode is reduced from the watt level to the mill watt level, thus the power supply problem of the wireless communication terminal under extreme conditions is solved.

Multi-architecture power distribution strategy for flexible DC interconnection system considering the capacity limitation

The flexible DC interconnection system, which cascades and unitedly controls several converter stations, can effectively improve the new energy consumption and significantly increase the power quality, thus has been widely used in the power grid. This interconnection system generally uses master–slave control strategy, where chooses one station as the master station to ensure the direct-side voltage’s stability and maintain the input and output power balance. However, in some emergency cases, the input or output power can increase to a huge value that even exceeds the capacity of the master station, which not only threatens the safety of the master station but also leads to power imbalance and abnormal fluctuation of the direct-side voltage. Therefore, to avoid the capacity exceedance of the master station, a multi-architecture power distribution strategy is proposed in this study, which sufficiently considers the capacity limitation in the system architecture and innovatively prioritizes the capacity factor in the control strategy of the master station. Furthermore, the proposed strategy also fully considers cases where the system contains different types of slave stations, such as the station with redundant power and the station that can support bidirectional power flow. The strategy then optimizes the power distribution and adjusts the power flow based on the system’s different architectures. The reliability and effectiveness of the proposed strategy are finally verified by simulation.

Development of programming tool for master station of control system

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System of Remote Weight Monitoring for Beekeeping

Existing remote weight monitoring systems in beekeeping have disadvantages: lack of scaling of the system within the apiary, limited use in conditions of poor mobile communication. The use of LoRa energy-efficient long-distance radio communication technologies is proposed. The architecture of the developed remote weight monitoring system for beekeeping has a "star" structure and consists of two types of devices: a master station, an end device with two-way data exchange. The master station - provides communication between the end devices of the system and the user through the mobile network. The end device - provides collection of data on the weight of the hive, ambient air temperature, data processing, data transmission to the master station. The parameters of the LoRa radio communication network are selected: propagation coefficient, coding speed, bandwidth frequencies of the communication channel. The time required for the transfer of one data packet between the end device and the master station is calculated. The results of the study of methods of filtering continuous noise and impulse noise of strain gauge weight sensor data using the Python programming language are presented: moving average filter, median filter, exponential average filter, Kalman filter. According to the results of the research of digital filtering methods, the final device of the remote weight monitoring system for beekeeping uses an exponential average filter with effective filtering of continuous noise and impulse noise. The schematic diagrams of the master station and the final device are presented. The hardware part of the master station consists of three functional blocks: The main functional block is a microcontroller; the communication unit consists of a mobile network modem and a LoRa radio communication modem; the functional power supply is represented by a lithium-ion battery and a solar panel. The final device is built using a microcontroller, an external analog-to-digital converter, a high-precision strain-gauge weight sensor, and a LoRa radio modem. The final device is powered by a lithium-ion battery and a solar panel. The devices of the remote weight monitoring system for beekeeping are built according to the modular and hierarchical principle.

Application of IEC60870-5-101 in distribution automation terminal remote operation and maintenance

The characteristics, structure of extended remote operation and maintenance protocol based on IEC60870-5-101, the normal or abnormal communication process of remote maintenance are introduced, and the transmission of operation and maintenance data between distribution master stations and distribution terminal units is effectively standardized. This paper expounds some common problems and solutions of remote maintenance under current wireless public network communication mode.

Distributed rule execution mechanism in smart home system

<p>Smart home systems become an interesting topics in the last few years. Many researchers have been studied some features. Most of smart home system use a centralized architecture know as centralized smart home system (CSHS). The centralizedmechanism is easy to manage and to configure. However, in fault-tolerant systemparadigm it produces a problem. The entire system will fail, if the master station fails.Another problem of CSHS is centralized mechanism gives more data-flow. This condition makes the system has a greater delay time. To solve the problem, we proposea distributed rule execution mechanism (DREM). Compared to the centralized mechanism, the DREM allows a device to provide its service without any commands fromthe master station. In this mechanism, since the information does not need to go tothe master station, the data-flow and the delay-time can be decreased. The experimentresults show that the DREM is able to mask the failure in the master station by directlytransmit the data from trigger device to service device. This mechanism makes the services provision without master station possible. The mathematical analysis also shows that the delay time of the service provision of the DREM is less than the delay time ofCSHS.</p>

Big Data Application Technology and Prospect Analysis in Smart Distribution Network

Intelligent power distribution network system main application technology including the communications, computer and network, the modern electronic technology, etc., adapter power automation system main components for the master station, terminal automation monitoring system and communication system, has formed a complete collection, transmission and processing in the integration of information system, to realize the remote management of distribution network. The application of big data technology in smart distribution network makes it more intelligent and ADAPTS to the needs of social development. This paper analyzes the application technology and prospect of smart distribution network big data.

Research on Primary Frequency Modulation Online Monitoring and Assessment Management System Under “Master–Sub” Control Station Model

In a modern power system, to realize the safe operation of units and maintain the frequency stability of the power network, various means of frequency modulation can be adopted. However, there are some deficiencies in the real-time monitoring and assessment management of primary frequency modulation (PFM). To solve these problems, a PFM online monitoring and management method based on the “master–sub” control station model in a wide area measurement system (WAMS) is proposed as a control strategy to support frequency modulation of units and assist power network assessment. In the hybrid monitoring system strategy of the master control station and sub control station, the sub control station is built locally in the power plant to monitor the operational status of the unit in real-time and calculate the PFM assessment index. The master control station is built in the dispatching center, receiving the assessment data uploaded by the sub control station and sending the PFM simulation test instruction. This strategy can effectively improve the real-time performance of dynamic monitoring and parameter calculation, and reduce the probability of frame loss and communication instability in long-distance data transmission. The experimental results show that the PFM online monitoring management control strategy based on the “master–sub” control station model can effectively monitor the unit and provide data support for PFM assessment.

Development of the generator inspection vehicle and the inspection equipment

AbstractThis article presents a development of a robot which is used for inspecting electrical generators. Traditionally, to inspect an electrical power generator, its rotor is required to remove first and the inspection task is then performed by human. This process consumes time and cost of operation. Moreover, there are risks to damage generator while removing the rotor as well as accidents during the operation. An alternative approach without removing the rotor by using robot inspection becomes important. Therefore, a small robot called generator inspection vehicle (GIV) has been developed for the purpose of the inspection without removing the rotor. The proposed robot's thickness is 20 mm height that is suited for using in small generators. By this size, small on‐board controllers installed in the GIV robot have been especially designed to reduce connections between the master station (i.e., a laptop and a joystick or controller pad) and the remote side (i.e., the robot). This approach requires only two wires for the connections. A new method for controlling the robot's alignment while operating inside the generator by using fusion signal from camera and inertial measurement unit (IMU) is also proposed. The robot can also carry equipment for specific tasks which are a wedge tightness detector (WTD) and an articulating gripper. Both of the proposed equipment, the WTD and the articulating gripper, are also presented. The proposed robot was tested in small generators, which their rotor diameter ranged from 980 and 1050 mm. Case studies of our design in field tests have also been reported in the article.

Power automation communication technology based on improved genetic algorithm

In order to better promote the development of power enterprises and improve the modern communication means of remote control system, the power automation communication technology based on improved genetic algorithm is proposed. Based on the improved genetic algorithm, the power automation communication model is divided into master station model, communication model and terminal model. The main station of power automation communication is located in the power dispatching center. Through power communication or wireless public network, the collected data is transmitted to power automation for centralized processing. The structure of power automation communication equipment is optimized, and the power automation communication scheme is improved, so as to better realize the research of power automation communication. The experimental results show that the power automation communication technology based on improved genetic algorithm has high monitoring accuracy, can effectively eliminate noise, and has high practical application value.

Modular modeling method and power supply capability evaluation for integrated hydrogen production stations of DC systems

Low-voltage DC distribution system has many advantages, such as facilitating the access of DC loads and distributed energies and improving the network’s stability. It has become a new idea for integrated hydrogen production stations. Power supply capacity and small-signal stability are important indexes to evaluate a low-voltage DC integrated system. Based on the master–slave control mode, this paper selects the typical star structure as the research object, constructs the system transfer function through the scalable modular modeling method, and further evaluates the impact of the high-order DC hydrogen production station integrated system on the hydrogen production capacity under the changes of the line length and master station position. The results show that the hydrogen production capacity of the system decreases gradually with the main station moving from side to inside. Finally, a practical example is analyzed by MATLAB/Simulink simulation to verify the accuracy of the theory. This study can provide an effective theoretical method for the structure optimization and integrated parameter design of low-voltage DC system.

A topology identification algorithm and device implementation based on smart switch core board

Due to the large scale, large number of equipment and complex structure of distribution network, relying on manual maintenance of distribution network topology model has a huge workload and poor intuitiveness of model information, which is difficult to ensure the integrity and correctness of distribution network topology model. This paper presents an algorithm to improve the adaptability of multi scene feature signal recognition based on the smart switch core board, and designs the local communication interaction flow design based on topology recognition function from the station area intelligent terminal to the smart switch. The identification technology combining power frequency distortion and characteristic current is adopted. In the identification process, there is no need for the master station to participate in analysis and control. Multiple stations in the same community can be carried out concurrently to automatically identify the connection relationship between distribution network equipment and line topology, and dynamically build a clear and complete household transformer relationship and distribution network topology to help operation inspection, marketing The lean management level of distribution network such as regulation and control has been improved.

Optimal locating method of edge computing device in cyber physical distribution system

With the development of interconnection of massive terminals, high maintenance of equipment data and complexity of network structure in distribution system, the traditional information processing mode based on single cloud master station has some disadvantages, such as high data transmission delay, high congestion, information far away from equipment and slow queuing processing. Edge computing can make local fast analysis and decision for data in the near terminal device side, which can effectively make up for the deficiency of cloud computing. As the cornerstone of edge computing, edge control processing node is the first premise to realize fast response control of cyber physical distribution system (CPDS). In this paper, a new method of edge computing node deployment is proposed for the distributed edge computing requirements of cyber physical distribution system, considering the cyber stability and power stability. The community theory based on distribution network power flow and line impedance is used to divide the edge computing autonomous region, and the calculation model of cyber stability and power stability of CPDS network is established, then the optimal deployment of CPDS edge computing nodes is solved by the hybrid entropy calculation of cyber and power. Finally, an improved standard example is used for simulation analysis. The simulation results show that the ECN deployment scheme proposed in this paper can effectively reduce network congestion, improve network response speed and realize optimal control of distribution network.

Fiber-optic joint time and frequency transmission with enhanced time precision.

We propose a high-precision joint time and frequency transmission scheme based on bidirectional wavelength division multiplexing transmission over an optical fiber link. The time signal is generated based on the phase-stable frequency signal with employment of a dedicated designed low-jitter event generator. Time synchronization is realized by eliminating the time difference between the time signals of the master and slave stations, which is determined by accurate two-way time comparison. In this way, thanks to the high stability of the frequency transmission, low jitter of the dedicated designed event generator, and the high accuracy of the two-way time comparison, a high precision time signal with enhanced time stability and accuracy can be obtained at the slave station, which is synchronized to the master station. Experimentally, a joint time and frequency transmission system is demonstrated over a 62-km urban fiber link. The results show a time stability in terms of time deviation (TDEV) of 3.5 ps/s and 430 fs/10,000 s, and an accuracy of better than 20 ps can be realized.

Artificial Neural Network-Based Ionospheric Delay Correction Method for Satellite-Based Augmentation Systems

Ionospheric delay is a critical error source in Global Navigation Satellite Systems (GNSSs) and a principal aspect of Satellite Based Augmentation System (SBAS) corrections. Grid Ionospheric Vertical Delays (GIVDs) are derived from the delays on Ionosphere Pierce Points (IPPs), which are observed by SBAS reference stations. SBAS master stations calculate ionospheric delay corrections by several methods, such as planar fit or Kriging. However, when there are not enough IPPs around an Ionosphere Grid Point (IGP) or the IPPs are unevenly distributed, the fitting accuracy of planar fit or Kriging is unsatisfactory. Moreover, the integrity bounds of Grid Ionospheric Vertical Errors (GIVEs) are overly conservative. Since Artificial Neural Networks (ANNs) are widely used in ionospheric research due to their self-adaptation, parallelism, non-linearity, robustness, and learnability, the ANN method for GIVD and GIVE derivation is proposed in this article. Networks are separately trained for IGPs, and five years of historical data are applied on network training. Principal Component Analysis (PCA) is applied for dimensionality reduction of geomagnetic and solar indices, which is employed as a network input feature. Furthermore, the GIVE algorithm of the ANN method is derived based on the distribution of the residual random variable. Finally, experiments are conducted on 12 IGPs over the East China region. Under normal ionospheric conditions, compared with the planar fit and Kriging methods, the residual reduction of the ANN method is approximately 15%. The ANN method fits the ionospheric delay residual error better. The percentage of GIVE availability under 2.7 m increases at least 25 points in comparison to Kriging. Under disturbed conditions, due to a lack of training samples, the ANN method is incompetent compared with planar fit or Kriging.

中国湿地生态站现状、发展趋势及空间布局

PDF HTML阅读 XML下载 导出引用 引用提醒 中国湿地生态站现状、发展趋势及空间布局 DOI: 10.5846/stxb202104130960 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院A类战略性先导科技专项（XDA23040203）；国家自然科学基金项目（42171105，41971133）；国家生态系统观测研究共享服务平台建设项目 Current status, development and spatial planning of China's Wetland Ecological Stations Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:湿地调查与监测是全面了解和掌握湿地变化，开展湿地保护和修复的前提和基础。湿地生态站是开展湿地长期监测和野外试验的平台，对研究湿地生态系统过程与功能，揭示湿地变化机理具有重要作用。系统梳理了我国现有的湿地生态站，分析了当前湿地生态站建设中面临的问题，指出：与国际主要生态观测网络相比，我国综合性湿地生态站数量较少、比例偏低，导致在湿地生态系统监测和评估上存在较大空缺；现有生态站存在层级结构不合理、监测指标体系不规范等问题，制约了国家尺度湿地生态系统监测评估的需求。研究基于中国湿地生态站的现状，提出综合性湿地生态站布局原则，认为：应反映湿地生态系统类型代表性及湿地的空间分布特征，体现综合站-区域站-卫星站的层级结构特点，服务国家湿地保护和生态修复的战略需求。按照上述布局原则，对今后综合性湿地生态站的空间布局提出建议。同时，对湿地站发展定位、聚焦的前沿科学问题、湿地联网研究及国际合作方面提出了展望。 Abstract:Wetland survey and monitoring is the prerequisite and foundation for comprehensively understanding and clarifying wetland ecosystem dynamics, and carrying out wetland conservation and restoration. Wetland Ecological Stations provide the platform for long-term wetland observation and in-situ experiments, which are indispensable in studying and revealing the processes, functions, as well as related mechanism of wetland change. There are some problems in the development of wetland ecological stations in China. Compared with the International Long-Term Ecological Research Network, the number and proportion of Wetland Ecological Stations in National Ecological stations are less and there are also some gaps on spatial planning of wetland ecological stations; in addition, wetland ecological stations are not laid out with obvious hierarchical structure (such as Master stations, Regular stations and Satellite stations), and the monitoring indicators and systems for wetland ecological stations are also not standard and uniform, which lead to limitations on monitoring and assessment of wetland ecosystem at national scale. In this study, we summarized and analyzed the status and problems in the development of Wetland Ecological Stations in China, and proposed the planning principles of the National Wetland Ecological Stations in existing National Ecological Stations System. We suggested that it should consider representativeness of wetland ecosystem types and the spatial distribution characteristics of wetlands in China, as well as to take account of the hierarchical structure of wetland stations and their combination to national development strategy and policy demand on wetland conservation and restoration. We proposed some targeted suggestions on spatial planning of China's Wetland Ecological Stations in the future based on the above principles. At the same time, the development orientation of wetland station was determined and the frontier and key scientific issues needing to be focused in the future were discussed, such as the changes of wetland landscape, lake eutrophication and invasive species control, climate change and carbon sequestration mechanism, etc. Finally, how to response to the national development strategy and policy demand was also analyzed. It is proposed to strengthen cooperation with international partners in the fields of biodiversity conservation and monitoring, climate change, transboundary wetlands and the conservation of migratory species. 参考文献 相似文献 引证文献

Research on Data Acquisition Technology of Distribution Automation Based on Internet of Things Communication Protocol

With the gradual application of the Internet of Things technology in the field of distribution automation, distribution terminals gradually adopt the Internet of Things protocol to communicate with the master station system of distribution automation. while the master station system of distribution automation supports the access of the traditional power dedicated protocol terminal, it faces how to solve the problem which how to access the distribution terminal of the network communication protocol. This paper proposes the MQTT protocol data acquisition architecture based on the existing master station system of distribution automation system. Through the research on the transmission characteristics of power distribution service data and MQTT protocol, the message structure of the MQTT protocol carrying power service data and the source maintenance process of the equipment model are designed., It realizes the direct collection of the terminal data of the distribution Internet of Things in an object-oriented way, gives full play to the value of the existing distribution master station, reduces investment costs, and saves system maintenance workload.

Research and Application of Power System Data Anomaly Identification Based on Time Series and Deep Learning

Abnormal data in the power system will reduce the accuracy of system state estimation and affect the safe operation of the power dispatch system. This paper proposes a data anomaly identification model based on time series and neural network, which establishes time series for various measuring points of the control master station, creates a time series group of associated measuring points based on the network topology, and extracts the sample characteristics of the time series. The neural network model is used to realize the intelligent identification of normal data and abnormal data. The neural network recognition results are compared with normal distribution and DBSCAN density clustering methods to verify the abnormal recognition performance of the neural network. Using a provincial power grid dispatch center operating data set as a training and testing sample, it verifies the advancement of the proposed method in the comprehensive performance of anomaly detection recall rate and precision rate and its feasibility in actual system application.