Substation Devices Research Articles

Communication Delay Modeling for Wide Area Measurement System in Smart Grid Internet of Things Networks

We present communication frameworks, models, and protocols of smart grid Internet of Things (IoT) networks based on the IEEE and IEC standards. The measurement, control, and monitoring of grid being achieved through phasor measurement unit (PMU) based wide area measurement (WAM) framework. The WAM framework applied the IEEE standard C37.118 phasor exchange protocol to collect grid data from various substation devices. The existing frameworks include the IEC 61850 protocol and programmable logic controllers (PLCs) based supervisory control and data acquisition (SCADA) system. These protocols have been selected as per the smart grid configuration and communication design. However, the existing frameworks have severe synchronization errors due to the communication delays of IoT networks in the smart grid. Therefore, this article designs the timing mechanism and a delay model to reduce the timing delay and boost real‐time measurement, monitoring, and control performance of the smart grid WAM applications. The result shows that the proposed model outperformed the existing WAM system.

디지털변전소 상호운용성 검증시스템 개발

Since KEPCO’s digital substation is not composed of a single manufacturer’s device, but consists of 4 to 6 different manufacturers’ devices, interoperability between devices is considered very important. IEC 61850 International Standard does not define a single way of expressing all information that intelligent electronic devices in substations must implement, but allows the freedom to implement it differently for each manufacturer. The reality is that the operating environment for S/W implementation, communication library, operation method for system operation, and response method for communication failures differ from manufacturer to manufacturer. For this reason, compatibility problems between devices occurred from the beginning of the introduction of digital substations and caused obstacles in substation operation. In this paper, by analysing various compatibility problems that occurred at the site, it explains digital substation interoperability test-bed that can select interoperability issues rather than simply device failures and execute test procedures to verify them in advance, and the verification system that can automatically carry out the whole test process.

110 kV substation relay protection

In this paper, the main electric wiring mode of 110kV substation is selected, the structure of substation is determined, and then the main wiring diagram is drawn. According to the design and load of the primary electrical connection, select the maximum and minimum operating modes to calculate the short circuit separately. Then, according to the short-circuit current parameters, the relay protection of transmission lines, transformers, busbars, etc. is set, and the configured protections include current quick-break protection, gas protection, and longitudinal differential protection. Finally, a comprehensive evaluation of the selected protection devices is carried out. Adding relay protection device in substation can send out fault signal and cut off fault line in time to reduce the occurrence of substation fault, so as to ensure the reliable power supply of users and enterprises.

Defect Texts Mining of Secondary Device in Smart Substation with GloVe and Attention-Based Bidirectional LSTM

In the process of the operation and maintenance of secondary devices in smart substation, a wealth of defect texts containing the state information of the equipment is generated. Aiming to overcome the low efficiency and low accuracy problems of artificial power text classification and mining, combined with the characteristics of power equipment defect texts, a defect texts mining method for a secondary device in a smart substation is proposed, which integrates global vectors for word representation (GloVe) method and attention-based bidirectional long short-term memory (BiLSTM-Attention) method in one model. First, the characteristics of the defect texts are analyzed and preprocessed to improve the quality of the defect texts. Then, defect texts are segmented into words, and the words are mapped to the high-dimensional feature space based on the global vectors for word representation (GloVe) model to form distributed word vectors. Finally, a text classification model based on BiLSTM-Attention was proposed to classify the defect texts of a secondary device. Precision, Recall and F1-score are selected as evaluation indicators, and compared with traditional machine learning and deep learning models. The analysis of a case study shows that the BiLSTM-Attention model has better performance and can achieve the intelligent, accurate and efficient classification of secondary device defect texts. It can assist the operation and maintenance personnel to make scientific maintenance decisions on a secondary device and improve the level of intelligent management of equipment.

A Model-Based Design of Distributed Automation Systems for the Smart Grid: Implementation and Validation

The paper aims at describing a model-based approach to design automation logics for fault location and supply restoration in medium voltage distribution networks. The application of automation functions along medium voltage feeders and, in particular, the installation of protection devices in secondary substations mandates the design and the implementation of complex logics to coordinate the operations of this hardware in case of fault occurrences. This synchronization is realized with the exchange of IEC 61850 GOOSE messages, but the correct usage of this information must be implemented in each protection device through dedicated logics, which are not in the common out-of-the-box system configurations. To support the introduction and the design of these logics, an automata-based approach has been proposed and successfully demonstrated in a real environment in the European research project IDE4L. This formal methodology has been introduced to simplify the design phase and to standardize the logics implemented in the protection prototypes realized in the project. The same models have also been used in the implementation phase with a semi-automatic code generation procedure, considering as a target system the software programmable logic controllers (soft-PLCs), available on the protection devices. Based on the test results and the short time to set up the test bench, this approach proved to be a reliable and effective way to implement complex medium voltage (MV) automation logics such those needed in modern smart grids.

Research on Real-time Reliability of Relay Protection System in Intelligent Substation

Because the intelligent substation is composed of a variety of intelligent electronic components, various types of information data will be generated during its operation. With the continuous implementation and rapid development of smart grid construction, the application of smart substations in power systems is becoming more and more extensive, and the number and scope of use are gradually expanding. In the face of the substantial increase in the commissioning of smart substations, people are paying more attention to the reliability of relay protection devices in smart substations during use. Strengthening research on the relay protection system of intelligent substations and improving the reliability of the system are urgent problems that need to be solved. The digitization of data information of the whole station is a typical feature of intelligent substations, on this basis, distributed relay protection can be realized; At the same time, the system-level status information can be identified and evaluated. Because there are too many spatial states, the calculation is very complicated. To solve this problem, this paper proposes to calculate the reliability of the relay protection device by Markov method, and then calculate in system level by GO method. Combining the Markov algorithm model with the GO method, the reliability of the relay protection system is calculated and analyzed, enabling the on-site operation and maintenance personnel to grasp the basic status of the relay protection device and the system operation in real time, obtain real-time feedback information, and better relay protection work of smart substations.

On the issue of using a robotic manipulator to perform operational switching in electrical distribution devices and substations

During the operation of power supply systems, a sufficiently large number of labor cost of operational personnel is required to perform operational switching. The classification of operational switching has been considered in the article; conclusions have been made about the possibility of using robotic manipulators for some of them. A description of the design of this device and the functions that it should have has been given. A block diagram of the collection and exchange of information and control signals for the power supply system is presented, in which the robot manipulator automatically performs a certain set of manipulations according to a predetermined algorithm or at the command of an operator. Conclusions are drawn on the appropriateness of using these devices in substations with large room for installing switchboards.

A high-precision synchronous signal acquisition device.

The synchronous and accurate acquisition of multiple features of states is key to assessing the state of power equipment. The highest recorded accuracy of currently available synchronous signal measuring devices in intelligent substations is the 0.2 class, which cannot satisfy the requirements of power equipment such as voltage and current transformers. The accuracy of measurement of a high-precision sigma-delta analog-to-digital converter (ADC) can reach the 0.05 class, but the phase error among several sigma-delta ADCs is large and dynamic because of inadequate real-time sampling. To solve this problem, this paper proposes a double-trigger-time digital conversion technology for synchronous and accurate measurement among sigma-delta ADCs. The results of tests show that its measurement accuracy can reach the 0.05 class.

Research on state prediction of secondary device in smart substation based on dynamic interval weighted fuzzy c-means algorithm

A weighted fuzzy clustering algorithm based on dynamic interval is proposed to solve the problem of inaccuracy of missing attributes in clustering. By selecting the index that can reflect the secondary equipment state of intelligent substation comprehensively and combining with the weighted fuzzy clustering algorithm based on dynamic interval, the clustering classification result of the whole secondary equipment state of intelligent substation can be obtained accurately. According to the result, the corresponding maintenance strategy is adopted. The experimental results show that the weighted fuzzy clustering algorithm based on dynamic interval can effectively improve the clustering accuracy and the stability of the convergence, which can be very good to adapt themselves to the secondary device state overhaul.

A Study on the Test Method of Local Information Processing Device in Digital Substation Based on IEC 61850

A Study on the Test Method of Local Information Processing Device in Digital Substation Based on IEC 61850

Equipment Failure Detection Method of Substation Based on Tunnel Robot

Indoor substation is critical facilities of power system, therefore inspection of substation equipment is crucial to ensure the security of power supply. Substation inspection robot can collection information through variety of sensors, then the appropriate approach is used to determine the operational status of the substation equipment. The state of most indoor substation device can be acquired by image collection, but this method is not applicable to all devices. A new method of monitoring the operational status of equipment in the substation is put forward in this paper. The audio signal is collected by dual channel collection equipment which is brought in the indoor intelligent robot. The angle information of collected signal is calculated according to signal procession theory. The operational status of equipment can be obtained easily by analyzing the angular information. Simulation result indicate the feasibility of the method. It combines audio signal procession and intelligent surveillance robot and the system is low cost and simple to realize with certain engineering value.

Summarize on Application of Arc Protection Device in Substation

Arc protection device plays an important role in ensuring the faults of switchgear in substation. This paper analyses the operation problems of switchgear in substation, analyses the characteristics and necessity of arc protection device, expounds the principle and system structure of arc protection, and puts forward the design method of arc protection, which can quickly remove the faults in the operation of substation, and ensures that guarantee the safe and stable operation of substation.

Real Time Operation of IEC 61850 Based Digital Substation

The advancement in technologies applied on substation studies are leading towards substation automation systems (SAS). In SAS network interoperability of substation devices is an important factor that needs good media of communication. IEC 61850 protocol has a greater role in device communications and protection functions of an integrated system. Also this standard can address the problem of interoperability of devices from various vendors. With the implementation of IEC 61850 standards in SAS networks, integration of latest devices like, intelligent electronic devices (IEDs), analog merging units (AMUs) and Ethernet networks are becoming possible. IEC 61850 standards will upgrade a conventional substation model into Digital Substation providing IEDs and modern substation devices are getting installed. In this paper IEC 61850 standard with its various operational levels have been studied for basic understanding of the protocol. A digital substation model with operational architecture has been shown and its various process bus communication messages have been discussed. To establish the concept of interoperability of subsation devices in a substaion model, a digital substation laboratory model has been developed here with IEC 61850 standard implementation. Real time analysis of protection functions with process bus communications of the substation model have been executed. The study of IEC 61850 standard and digital substation with its real time hardware test results will give the reader a clear idea about digital substations, substation devices interoperability operations and protection functions. This implementation and application of IEC standards in substation communication and protection functions can get used effectively in future for testing some other network topology.

Study on the Adjustment of the Network Interface for the Station Domain Protection Device Based on RTDS

With continual development of smart grid construction, digital substation devices based on the specification IEC 61850, such as substation-area backup protection, have been widely applied. According to the “Technical requirements for the substation-area backup protection control device of the new generation of intelligent substation”, this paper put forward the debugging scheme of all digital network interface based on RTDS. Through the introduction of the RTDS software and hardware platform of the whole process building and commissioning, and by constructing substation simulation model and configuring GTNET-GSE card and GTNET-SV card, a closed-loop test system of substation-area backup protection device is completed, also this process development verification interface debugging method and configuration files have a certain practical value. The simulation of substation typical fault conditions and device data receiving processing mechanism can effectively meet the state grid enterprises standard Q/GDW11053-2013 for protection device test project requirements, and this test can significantly improve the smart substation integrated debugging efficiency.

Behavior Analysis and Anomaly Detection for a Digital Substation on Cyber-Physical System

The electric power system infrastructure has begun to adopt digital information technologies such as transmission control protocol/internet protocol (TCP/IP) and Ethernet infrastructures. With this adoption, information technology-centric network and system management (NSM) tools are used to manage the intermediate communication systems and electric devices in digital substations. However, the technology to monitor the cyber–physical System (CPS) statistics for the intelligent electronic devices (IEDs) and serial communication for a digital substation does not exist yet. In this paper, we aim to propose cyber-physical analysis methodologies of a digital substation system, concerning issues of (1) International Electrotechnical Commission (IEC) 62351-7 based network and system management, (2) behavior analysis of the CPS, (3) cyber–physical anomaly detection systems, and (4) a testbed for a digital substation. By collaborating with Electric Power Research Institute (EPRI), a cyber security testbed for the digital substation has been developed to implement the use cases and analyze potential security threats. Newly integrated methodologies for information handling are expected to lead to improved safety and reliability for the CPS of electric power grid systems.

Testing of Intelligent Electronic Device (IED) in a digital substation

This study reports on experience gained during factory testing on a pilot project digital substation. Testing IEDs in a digital substation is dependent on how test and simulation functionality as defined by the IEC61850 is implemented by the vendors, and also requires a different approach to testing compared to testing on a conventional station. This study highlights limitations imposed on testing due to missing IED test facilities, as well as the need for the end customer to fully specify IED functionality to ensure vendor interoperability.

Wide-area measurement system-based supervision of protection schemes with minimum number of phasor measurement units.

Cascade tripping of power lines triggered by maloperation of zone-3 relays during stressed system conditions, such as load encroachment, power swing and voltage instability, has led to many catastrophic power failures worldwide, including Indian blackouts in 2012. With the introduction of wide-area measurement systems (WAMS) into the grids, real-time monitoring of transmission network condition is possible. A phasor measurement unit (PMU) sends time-synchronized data to a phasor data concentrator, which can provide a control signal to substation devices. The latency associated with the communication system makes WAMS suitable for a slower form of protection. In this work, a method to identify the faulted line using synchronized data from strategic PMU locations is proposed. Subsequently, a supervisory signal is generated for specific relays in the system for any disturbance or stressed condition. For a given system, an approach to decide the strategic locations for PMU placement is developed, which can be used for determining the minimum number of PMUs required for application of the method. The accuracy of the scheme is tested for faults during normal and stressed conditions in a New England 39-bus system simulated using EMTDC/PSCAD software. With such a strategy, maloperation of relays can be averted in many situations and thereby blackouts/large-scale disturbances can be prevented.This article is part of the themed issue 'Energy management: flexibility, risk and optimization'.

Statistical characteristics of transient enclosure voltage in ultra-high-voltage gas-insulated switchgear

Transient enclosure voltage (TEV), which is a phenomenon induced by the inner dielectric breakdown of SF6 during disconnector operations in a gas-insulated switchgear (GIS), may cause issues relating to shock hazard and electromagnetic interference to secondary equipment. This is a critical factor regarding the electromagnetic compatibility of ultra-high-voltage (UHV) substations. In this paper, the statistical characteristics of TEV at UHV level are collected from field experiments, and are analyzed and compared to those from a repeated strike process. The TEV waveforms during disconnector operations are recorded by a self-developed measurement system first. Then, statistical characteristics, such as the pulse number, duration of pulses, frequency components, magnitude and single pulse duration, are extracted. The transmission line theory is introduced to analyze the TEV and is validated by the experimental results. Finally, the relationship between the TEV and the repeated strike process is analyzed. This proves that the pulse voltage of the TEV is proportional to the corresponding breakdown voltage. The results contribute to the definition of the standard testing waveform of the TEV, and can aid the protection of electronic devices in substations by minimizing the threat of this phenomenon.

Cyclic Digital Transmission Communication Software Design and Realization

The devices in the intelligent substation are required to transmit and process information in Smart Grids. On account of the modular design technology, serial port communication becomes the main technique used to connect intelligent modules as its high reliability, flexibility, and ease-of-use features, which is also used in the communication of the data collection board and the conversion board of the three-phase circuit breaker. Cyclic Digital Transmission (CDT) protocol, which is issued by the Ministry of Energy of China, is widely used in the communication of the power system in China. The framework of CDT protocol is composed of the function, the information word, the transfer rules and the frame structure. The CDT protocol that adopts STM32 as the CPU is developed in this paper, so as to achieve highly automated grid scheduling and reliable and stable communication. Some functions and technologies of STM32 such as Timer, USART, DMA, etc., are described in detail. The test results indicate that the serial port reliable communication based on CDT protocol can be realized, which also shows that the data collection board can communicate with the dispatch center via the protocol conversion board. Keywords: Cyclic digital transmission protocol, communication, serial port, smart grid, switchgear.

Research on Operation Management Based on the Intelligent Substation

With the rapid development of economy in our country, current the construction of intelligent power grid, the substation equipment and device also began to high science and technology development. Currently the substation has basically realized the modernization and automation, the equipment is set technology. In this case, you need to adapt to the high level of operation management, so as to effectively guarantee the normal operation of the equipment, avoid the happening of the fault. But in the current our country the majority of the substation, its operation and management is still in the extensive mode of management, not compatible with the level of automation and modernization, which result in the low productivity of substation operation, frequent accidents, unable to meet the needs of the modern equipment management, so strengthening the operation of the substation management is very necessary, will effectively promote the stability and reliability of the power grid operation. This paper studies the substation compositions, introduces the development of substation. Finally, the advantage of smart substation, the key technology and management are analyzed in detailed.