Substation Communication Research Articles

A Review Reliability and Availability Analysis of IEC 61850 Based Substation Communication Architectures

Modern Ethernet technology's high-speed capabilities enable efficient data transfer, and its leadership in the LAN space further distinguishes Ethernet as an intriguing communication method. For important substation automation applications to operate successfully, communications must meet cost, performance, and reliability requirements technology for substation automation management. The IEC 61850 standard was published by the International Electro-Technical Commission (IEC) to provide interoperability among enterprise substation automation systems for communication networks within power substations. This standard specifies Ethernet-based communication systems for substation automation systems (SAS). With the aid of Ethernet switches, Ethernet offers versatility in terms of configuring different designs. On the other hand, before using appropriate Ethernet architectures for critical applications in substations, they must be assessed for availability and reliability. This study uses the reliability block diagram (RBD) approach to analyse the availability and reliability evaluation of practical Ethernet Cisco device topologies. With a typical transmission substation in mind, dependability block diagrams for intra-bay and inter-bay communications have been created. Additionally, the dependability and accessibility of the actual Ethernet topologies have been compared, and some recommendations have been derived from the findings. These recommendations include the following Index Terms: substation automation systems (SAS), availability, IEC 61850, smart electronic device (IED), and dependability.

Visualization display and exit fault diagnosis of secondary virtual real circuit in intelligent substation

Most communication in smart substations uses fiber optic connections to connect secondary equipment now. Due to the lack of intuitive connection between devices, it leads to difficulties in monitoring and relay protection. In order to solve the problems of visualizing, monitoring, and diagnosing secondary virtual circuits in the operation and maintenance of intelligent substations, a comprehensive monitoring technology system for secondary virtual circuits in intelligent substations is constructed. Firstly, a breadth first search algorithm is proposed to sort out the physical connection relationships between secondary devices, which achieves visual display of secondary virtual circuits. Then, based on deep search fault inference algorithms, it can diagnose and locate the fault area. Through the massive data source of intelligent substations, multiple information fusion can be achieved. By applying the D-S evidence theory, precise fault localization can be achieved. Finally, the proof table method is used to determine the type of fault and to meet the practical application requirements for the operation and maintenance of secondary equipment in intelligent substations.

Evaluation on the method of restoring the complex communication environment in the field based on the complex low pressure platform simulation platform

Abstract In recent years, with the development of smart grids, people have increasingly high requirements for the safety, stability, and reliability of smart grid operation. In actual operation, smart grids require real-time monitoring and control, while for low-voltage power lines, power line carrier communication is required for data transmission. However, in practical applications on site, the low-voltage power line environment is complex, with ground faults, electrical equipment interference, and other situations that can affect communication quality and reliability, leading to a decrease in the effectiveness of real-time monitoring and control. The research in this paper is based on a complex low voltage platform simulation platform to restore the on-site complex substation communication environment. The purpose is to improve the efficiency of automatic meter reading systems by using various communication methods in low-voltage substations, such as wireless public network point-to-point data transmission, optical fiber communication data transmission, power line carrier data transmission, etc. Automatic meter reading systems are an important means of low voltage substation communication. This article experimentally tested the maximum personnel allocation for meter reading using low voltage carrier communication technology, which was 8 people smaller than the maximum personnel allocation for traditional meter reading, and the minimum personnel allocation was 8 people smaller than the traditional meter reading personnel allocation. The electricity accuracy of meter reading using low voltage carrier communication was up to 96 %, while the electricity accuracy of traditional meter reading was 70 %. The maximum accuracy of line loss statistics for low voltage carrier communication technology meter reading was 90 %, while the maximum accuracy of line loss statistics for traditional meter reading was 68 %. The frequency of load anomalies found in low-voltage carrier communication meter readings within a month ranged from 30 to 60 times, while the traditional meter readings concentrated on 10–25 times. From these data, it is clear that communication meter reading in low-voltage station areas has advantages over traditional meter reading.

Modeling and assessing load redistribution attacks considering cyber vulnerabilities in power systems

Introduction: Load Redistribution (LR) attacks, as a common form of false data injection attack, have emerged as a significant cybersecurity threat to power system operations by manipulating load buses’ measurements at substations. Existing LR attack methods typically assume that any substation can be equally attacked, contributing to the analysis of LR attacks in power systems. However, the diversity of cyber vulnerabilities in substation communication links implies varying costs associated with falsifying load buses’ measurements. Thus, quantitatively evaluating these costs and analyzing the impact of LR attacks on power systems within cost constraints holds practical significance.Methods: In this paper, we employ a Bayesian attack graph model to characterize the intrusion process through cyber vulnerabilities. The costs of falsifying load buses’ measurements at substations are quantitatively evaluated using the mean time-to-compromise model. Subsequently, from the attacker’s perspective, we propose a bi-level optimization model for LR attacks, considering the mean time to compromise in conjunction with limited attack resources and power flow constraints.Results: Simulations conducted on the IEEE 14-bus system illustrate the influence of cyber vulnerabilities on LR attacks within power systems. Furthermore, we verify that the attack scenario of the existing LR attack model aligns with a case of the proposed bi-level LR attack model when there is sufficient attack time to compromise all communication links.Discussion: The findings of this research demonstrate that the impact of cyber vulnerabilities on LR attacks can be quantified by assessing the attack costs. Effective management of LR attacks can be achieved under cost constraints through optimization methods. These insights contribute to enhancing network security strategies for power systems, mitigating potential threats posed by LR attacks in power system operations.

Performance Analysis of Routable GOOSE Security Algorithm for Substation Communication through Public Internet Network

Traditional unidirectional power systems that produce large-scale electricity and supply it using an ultra-high voltage power grid are changing globally to increase efficiency. Current substations’ protection relays rely only on internal substation data, where they are located, to detect changes. However, to more accurately detect changes in the system, various data from several external substations, including micro-grids, are required. As such, communication technology regarding data acquisition has become an essential function for next-generation substations. Data aggregators that use the GOOSE protocol to collect data inside substations in real-time have been developed, but data acquisition from external substations is challenging in terms of cost and security, so only internal substation data are used. This paper proposes the acquisition of data from external substations by applying security to R-GOOSE, defined in the IEC 61850 standard, over a public internet network. This paper also develops a data aggregator based on R-GOOSE, showing data acquisition results.

Multi-Scale Traffic Aware Cybersecurity Situational Awareness Online Model for Intelligent Power Substation Communication Network

Substation communication network (SCN) provides real-time, high-speed, and reliable data transmissions for the advanced monitoring and control functionalities, which are facing increasing cyberspace threats and attacks. Efficient threat perception and cyber situational awareness are essential to enhance secure and reliable SCN operations. This article explores multiscale SCN traffic pattern characteristics with holistic network traffic, separated network traffic for included devices (especially IoT devices) and separated network traffic of certain types of protocol. The proposed online traffic-oriented SCN traffic anomaly detection and cyber situational awareness models are designed for the network anomalies and cyber-attacks that could cause network traffic pattern variations. We leverage a fractional autoregressive integration moving average (FARIMA)-based dynamic threshold model to detect abnormal traffic patterns without sophisticated computations or deep packet inspection. The SCN real-time operation conditions are timely quantified through the statistical methods with the alliance of SCN topology and protocols. The cyber situational awareness model is further carried out to evaluate the most affected protocol and security risks of various devices in SCN using Grubbs’ test. The experiment results are carried out based on a real 110-kV intelligent power substation. The numerical results confirm the comparative low mean square error (MSE) and low complexity of the online traffic characterization when forecasting holistic network traffic and separated network traffics. Furthermore, the timely and quantified cybersecurity risk analysis is conducted based on the SCN traffic with varying scales to detect cyberspace threats and identify the high-risk SCN devices and the most affected protocol.

Smart Substation Communications and Cybersecurity: A Comprehensive Survey

Smart Substation Communications and Cybersecurity: A Comprehensive Survey

Application of Photoelectric Sensor Network in Substation Network Communication System

Photoelectric sensor refers to the sensor based on photoelectric effect. In recent years, with the continuous development and stability of photoelectric sensor, more attention has been paid to its wide application and practicability in substation. The substation communication control system will be affected by the communication system structure and communication mode, so it is necessary to make a comprehensive analysis and concrete judgment to find the best control system method and application. Because of its good insulation, strong anti-interference ability, small size and light weight, photoelectric sensors are widely used in substation communication systems. The application of photoelectric sensors in substation communication system has changed the substation communication system and structure. This paper analyzes the principle and technical characteristics of photoelectric sensor, and discusses its influence on structural communication of substation communication control system. As a new type of electronic transformer, the application of electric sensor will have a profound impact on substation automation system.

Construction of Intelligent Substation-Optimized Networking Communication Network Based on Source-Network-Load Interaction Environment.

Smart grids, which possess flexibility, cleanliness, safety, economy, and friendliness, have drawn a lot of attention from all over the world in an era of rapid social and economic development, power technology change, and energy and environmental constraints. However, there are still issues with the design, installation, and operation of smart substations, such as insufficient LAN integration, difficulty quantifying network performance, and inability to keep track of communication. The basic meaning and key technologies of substation communication standards are used as the research object in this paper, and the basic attributes of substation data flow, such as source, type, and function, are qualitatively analyzed. The mathematical model that is most closely fitted is 2.8% more effective. The research object is the topology of the process bus. Through the comparison of various solutions, including star topology, ring topology, bus topology, and mesh topology, the advantages and disadvantages of each topology networking scheme are revealed along with the particular functional requirements of the substation process layer. Further discussion is given to the crucial topology-related technologies of network congestion and flow control.

Towards Latency Bypass and Scalability Maintain in Digital Substation Communication Domain with IEC 62439-3 Based Network Architecture.

Parallel redundancy protocol (PRP) and high-availability redundancy protocol (HSR) are widely adopted protocols based on IEC 61850 standard to support zero recovery communication networks for time-critical and reliable interactions in power system substations. However, hiring these protocols comes with technical and economic constraints that impact the size of the substation network arrangement. Therefore, we will undertake a theoretical analysis of HSR, PRP, and their combinations to reach a maximum number of nodes in different substation communication architectures regarding IEC 61850 standard message time constraint requirements and IEC 62439-3 standard regulations. We will validate our findings through a simulation in the OPNET Modeler environment. In addition, we considered bandwidth efficiency by prohibiting the extra circulation of packets in the redundancy Box (RedBox) and QuadBox implementation as interfaces for HSR and PRP connection and HSR rings interconnection, respectively, which represent the main hindrance in utilizing the combination of these protocols.

Effect of VLAN configuration on IEC 61850 sampled values

IEC 61850, the standard for communication in power utility, has solved the interoperability problems between different vendors in substation communication networks (SCNs). However, most studies on SCN that use IEC 61850 were conducted using computer-based simulations or commercial equipment with fixed functions. In this study, an experiment on an SCN was conducted using real equipment such as a network switch, Raspberry Pi, and a mini PC. A cyclic data model was used for the traffic generation of sampled values (SVs) according to IEC 61850. The effect of applying a virtual local area network (VLAN) in the SCN on the transfer time and throughput of the SV frames was measured. In addition, when using IEEE 1588 in the time synchronization process, it was verified that the clock offset remained unaffected irrespective of the use of VLANs or changes in the sampling frequency. The experimental results can serve as guidance for the actual planning and construction process of SCNs.

Reliability of IEC 61850 based substation communication network architecture considering quality of repairs and common cause failures

Mission-critical IEC 61850 system architectures are designed to tolerate hardware failures to achieve the highest reliability performance. Hence, multi-channel systems are used in such systems within industrial facilities to isolate machinery when there are process abnormalities. Inevitably, multi-channel systems introduce Common Cause Failure (CCF) since the subsystems can rarely be independent. This paper integrates CCF into the Markov reliability model to enhance the model flexibility to investigate synchronous generator intra-bay SCN architecture reliability performance considering the quality of repairs and CCF. The Markov process enables integration of the impact of CCF factors on system performance. The case study results indicate that CCF, coupled with imperfect repairs, significantly reduce system reliability performance. High sensitivity is observed at low levels of CCF, whereas the highest level of impact occurs when the system diagnostic coverage is 99% based on ISO 13849-1, and reduces as the diagnostic coverage level reduces. Therefore, it is concluded that the severity of CCF depends more on system diagnostic coverage level than the repair efficiency, although both factors impact the system overall performance. Hence, CCF should be considered in determining the reliability performance of mission-critical communication networks in power distribution centres.

Matching Learning-Based Relay Selection for Substation Power Internet of Things

Wireless sensor network (WSN) can effectively solve the problems of weak coverage, blind coverage, and low survivability of smart substation communication networks by deploying multiple relay nodes and adopting multihop transmission. However, there are still some challenges in the traditional relay selection strategy of WSN in substation, including incomplete information and the selection conflicts among multisource nodes. In this paper, we propose a matching learning-based relay selection mechanism for WSN-based substation power Internet of things (SPIoT). Firstly, considering the electromagnetic interference caused by the operation of high-voltage equipment, a multihop transmission model of SPIoT is built. Furthermore, based on the upper confidence bound (UCB) algorithm and matching theory, a matching learning-based relay selection (MLRS) algorithm is proposed to minimize the energy consumption of SPIoT devices. Simulation results demonstrate that MLRS outperforms existing algorithms in terms of energy consumption and optimal selection probability.

A methodology for the evaluation of the message transmission delay over IEC 61850 communication network — a real-time HV/MV substation case study

The growing intelligence of the nowadays distribution grids is due to the integration of Information and Communication Technologies (ICTs). Such a development is converting the traditional grid into the smart grid concept. Communicating over a reliable ICT infrastructure, distributed Intelligent Electronic Devices (IEDs) perform supervision, protection, and control of the smart grid. The communication network is not errorless, and any error of the underlying communication network can degrade the power grid performance or even cause instability in it. Hence, there is a necessity to obtain a modeling method to analyze its Quality of Service (QoS). One of the most important quality measures of the Substation Communication Network (SCN) traffic is the message transmission delay. Thus, this paper proposes a methodology to evaluate the message transmission delay through an analytical model. To estimate the transmission delay, a port connection model represents the message distribution model. Then a traffic-flow-source model, and a traffic-flow-service model are applied to characterize each flow while it is served through different ports. Finally, delay is calculated based on the corresponding flow and service information. The estimation model is applied on an IEC-61850-MMS (Manufacturing Message Specification)-based communication scenario for a load-shedding goal that is considered over a real reduced-scale HV/MV smart substation test bench. The estimated results are compared to the measured values by the Wireshark network analyzer that indicates an estimation error of less than 10%.

Smart substation network quality monitoring and fault prediction

The smart substation communication network is the basis for information sharing of various devices in the substation. Its operation status has an important impact on the safe operation of the substation and even the power grid. Therefore, real-time status monitoring of the smart substation communication network is becoming more and more important. Aiming at the problems of single dimension, insufficient real-time performance and manual fault analysis in existing substation communication network state monitoring technology, this paper proposes a method of smart substation communication network state monitoring and fault prediction based on network communication quality. This paper uses switch ACL technology and coloring technology to obtain communication quality indexes such as bandwidth utilization, delay, and packet loss rate in real time; based on a multi-dimensional evaluation algorithm, a comprehensive evaluation model of network communication quality is constructed; the model of the relationship between abnormal network communication quality and failures is established. Finally, real-time monitoring of network communication quality and fault prediction are realized. The application analysis in a typical 110 kV substation shows that this method can effectively evaluate the network communication quality and accurately predict failures, and can guide operationer and maintenaner to quickly restore the normal operation of the communication network.

Reliability Analysis of Optical Path Automatic Protection Switching in Ubiquitous Power Communication Network

The reliability of power communication network plays an important role in the safe operation of ubiquitous power communication network. In this paper, the reliability model of power communication system is established by adopting the idea of hierarchical modeling. To begin with, the top-down decomposition method is used, the typical distribution network communication system is decomposed into terminal layer subsystem, access layer subsystem, substation communication layer subsystem and master station control layer subsystem. Next, the parameters such as mean time to failures, mean time between failures, mean time to repair and other parameters are used to evaluate the reliability of basic communication products. The reliability of each subsystem is evaluated by non redundant system, complete redundancy system, partial redundancy system and by-pass system; Finally, The bottom-up synthesis method is used to evaluate the reliability of the whole network according to the topological structure of the system. The reliability analysis method proposed in this paper provides a theoretical basis for the reliability evaluation method of power communication network.

Multi-state IEC-61850 Substation Communication Network based on Markov partitions and symbolic dynamics

Abstract Substation Communication Networks (SCN) make the digitalisation of power distribution centres possible. In recent times, combinatorial analysis methods are used to evaluate the reliability and availability of IEC-61850 based SCNs. Although the approach is conceptually simple and easy to use, it does not incorporate imperfect repairs that often occur during the system’s useful life and diagnostic coverage. Hence, reduced system performance is experienced for this reason, which is worsened by digital-based systems that require unique expertise to support and maintain the system. In this paper, the reliability and availability of multi-state IEC-61850 based SCN is modelled using structure-function and Markov process to incorporate imperfect repairs and system diagnostic coverage. Thereafter, the impact of repair efficiency on the system’s reliability performance and its dynamical behaviour is investigated in the context of Markov partitions and linear dynamical systems incorporating matrix similarity concepts. The case study results demonstrate that the system’s reliability performance based on mean system state transitions is highly dependent on the level of quality of repairs (viz. repair efficiency and diagnostic coverage) on the system. The results also indicate that the mean state transitions are very sensitive to low repair efficiency levels observed from the eigenvalues’ response to incremental repair efficiency. Hence, the quality of repairs cannot be ignored for mission-critical substation communication networks.

Investigation of an IEC 61850 standard-based process bus implementation of a protection and control scheme for parallelly connected transformers

PurposeThis paper aims to focus on the implementation of the International Electrotechnical Commission (IEC) 61850–9-2 standard based process bus with merging units (MUs) and sampled values (SV) to improve the protection and control systems. The digital process interface is important to be included on the process bus level.Design/methodology/approachThe IEC 61850–9-2 process bus standard is not extensively used in regard to SV when the IEC 61850 standard is implemented by power utilities. Many protection and control intelligent electronic devices (IEDs) are connected to a substation communication network, routers and switches using fibre-optic linked Ethernet. However, inductive current transformers (CTs) and voltage transformers (VTs) secondary circuits are still hardwired to the IEDs. The paper highlight issues with the copper wires for currents signals and how these issues can be eliminated by using the MUs and the SV protocol. The voltage regulator control IED of each transformer is required to regulate the voltage level of the secondary side bus bar it is connected to. All the regulating IEDs of parallel-connected transformers are required to communicate with each other to share information. They collectively control the bus bar voltage depending on the switching configuration of the parallel transformers.FindingsIt is shown that process bus information such as the high voltage switchgear status information of primary plant in the yard, can be used to improve the substation protection and control systems. The power transformer protection and voltage regulator control are focused on.Research limitations/implicationsThe deliverables of the research work can be applied in: The Centre for Substation Automation and Energy Management systems of the Department of Electrical Engineering, power utilities and other establishments using power systems and digital substations in the electrical supply industry. The research work on the thesis led to the development of a laboratory test-bench where students can learn and understand the basics of the IEC 61850–9-2 SVs principles. The test-bench components such as the IEDs, real-time digital simulator, standalone MUs and Ethernet equipment can be used for future research applications. The test-bench can be used to demonstrate during course work for students at the University, the basics of digital substations using a process bus network with IEDs, MUs and Ethernet equipment.Practical implicationsThe research work showed where lab equipment is getting outdated and future equipment will be required for research work in IEC 61850–9-2 process bus.Originality/valuePower utilities can benefit from implementing the IEC 61850 part 9–2 of the standard and by using MUs and other process interface information in substations. A cost reduction in high voltage equipment, substation installation and commissioning costs and better performance of protection and control system can be achieved.

Implementation of Secure Sampled Value (SeSV) Messages in Substation Automation System

IEC61850 is the mainstream of the development for substation automation. This paper presents a practical consideration and analysis for implementing a secure sampled measured value (SeSV) message in substation automation system. Due to the lack of security features in the standard, IEC Working Group 15 of Technical Committee 57 published IEC62351 on security for IEC61850 profiles. However, the use of authentication methods for SV based on IEC62351 standards are still not integrated, and computational capabilities and performance are not validated and tested with commercial grade equipment. Hence, this paper shows the performance of security feature enabled SeSV packets transmitted between protection and control devices by appending a message authentication code (MAC) to the extended IEC61850 packets. A prototype implementation on a low cost commodity embedded system has proved that the MAC-enabled SV message can fully secure the process bus communication in the digital substation with negligible time delay.

Sensitivity and elasticity of multi-channel IEC-61850 Substation Communication Networks to imperfect repairs

The reliability, availability and system dynamics of a repairable multi-channel IEC-61850 based mission-critical Substation Communication Network with imperfect repairs can be determined by analysing the magnitudes and the layout formation of the eigenvalues of the transition probability matrix. The disadvantage of only using the eigenvalue analysis method is that it focuses on the asymptotic state of the system, and does not account for the system state transient behaviour, which makes the optimisation of the system at subsystem level to be challenging. In this paper, a complimentary analysis technique that advances the eigenvalue analysis method is presented based on the concept of absorbing Markov Chain and matrix calculus techniques. The objective of the study focuses on the responsiveness of the system reliability performance to repair factors. The results of the case studies indicate that system performance is very dependent on the diagnostic coverage of the individual subsystems compared to their repair efficiencies, particularly for high diagnostic coverages at 99% and 90% based on ISO 13849-1 for subsystems A and B in a ‘one-out-of-two’ scheme configuration. Therefore, the results reveal that emphasis should be more on the system diagnostic capability because it is embedded in the system design itself that cannot easily be changed at a later stage considering that it would be too expensive and require plant downtime for implementation and testing as well. • Responsiveness of multi-channel IEC-61850 Communication Network to repair factors. • Significance of system fault diagnostics and repairs for mission-critical systems. • Reliability performance based on absorbing Markov chain and matrix calculus. • Mean state transitions and system dynamics based on eigenvalue analysis.