Increasing the Reliability of Computer Network Protection System by Analyzing its Controllability Models

This paper introduces a technique for assessing the reliability of protection and control systems using reliability models and event tree analysis. This technique allows a quantitative reliability assessment to be made, which can then be used to determine the effect of integrating different protection and control functions into a single unit. The term reliability when applied to protection system failure can be considered in terms of dependability and security. Dependability is defined as the probability that the protection operates satisfactorily when required, i.e. it does not fail to trip. Security is defined as the probability that the protection does not operate when not required to do so, i.e. it does not produce unwanted trips. Dependability results are given in this paper for feeder protection schemes based on differential protection, distance protection and combined differential and distance protection. The effect on the dependability of these schemes of including a separate and an integral intertrip unit is also considered. The former is housed in its own hardware, and the latter is integrated into the differential protection. Both intertrip units can be activated by either protection.

Protection system in a power system domain plays a vital role as watchmen to safe guard power system apparatus in the event of faults. The integrity and effectiveness of these watchmen is heavily dependent on the reliability of the components that makes up the system. One of the main components in a protection system is protective relays that provides decision making element for correct protection and fault clearing operations. Failure of the protection devices may reduce the reliability of the power system protection that will impact the overall performance of the power system. Hence it is imperative for power utilities, such as Tenaga Nasional Berhad (TNB) to assess the reliability of protective relays to assure it will perform its intended function without failure. This paper will discuss the application of reliability block diagram (RBD) to assess the reliability and availability of a typical 132kV transmission overhead line protection system using historical failure data of protective relays.

Introduction. In the United States, Europe, and Asia, there have been spikes in cyber attacks on protected and confidential information (including bank data, personal data, and confidential business information) over the period 2000-2020. Data protection in systems with complex architectures is a complex and non-trivial solution, which is suitable for flexible self-tuning and self-learning tools, such as neural networks as state modern studies. The described above state of things stipulates the importance and topicality of the direction of our research. Our research raises the question about the economic study of the data but attempts to create a mathematical apparatus to cause a loss of data in digital form, not made before The purpose of the study is to propose and test the calculation of the economic value of the data loss and economic benefit from data protection with multi-level neural networks. Results. Nowadays, almost every business that has access to the Internet has a threat of losing protected data, including banking data. To prevent this, the company must comply with the data protection management regulations. As an example, we studied the process of neural network reaction to an attack and its detection, when two types of attacks are threatened: botnet and UDP flood. Due to the result of a quick response to detect suspicious activity, neural network methods are excellent for use in economic analysis, because the neural network logs every event for every millisecond. Conclusions. As a result of using neural network tools for economic analysis of data protection in modern systems with complex architecture, we were able to obtain stable results of responding to an emerging attack in order to obtain protected data. Such protection is a preventive measure for the possibility of reducing business losses in the event of data loss. As we can see, the management of protection of systems with complex architecture is necessary for each company with the specified data level.

Calibration and validation are two stages in the development of a performance model of a computer system during which the degree of confidence in the model is established. This paper describes a case study of the calibration and validation of a hybrid simulation/regression Load Adjusting Model of a batch computer system. During calibration, a given workload trace was applied to the Load Adjusting Model and the parameters of the model were adjusted using an iterative tuning procedure. During validation, the parameters of the model, established during calibration, were kept constant and the model was tested using different workload traces.

Protocols of information protection in computer networks and systems are investigated. The basic types of threats of infringement of the protection arising from the use of computer networks are classified. The basic mechanisms, services and variants of realization of cryptosystems for maintaining authentication, integrity and confidentiality of transmitted information are examined. Their advantages and drawbacks are described. Perspective directions of development of cryptographic transformations for the maintenance of information protection in computer networks and systems are defined and analyzed.

For several decades, the power system protection relay has experienced many important changes, from a purely electromechanical type to the mixture of electronic and electromechanical type, then to fully static, and now fully numerical relays based on microprocessors. In the transformer protection area, similar changes can be seen. It is a dream for protection engineers to have a system that not only has many different functions for customer options, but also can be easily configured for different applications. On the other hand, it is expected to have control functions such as on load tap changer control function in combination with a protection system so that a protection and control system can be formed within one hardware and software system. With the fast development in the area of digital technology, the hardware and software must be possible to provide economic solutions regarding the cost of functions and hardware cards for a dedicated application. It is the motivation to build a powerful transformer protection and control system in order to fulfil the requirement from different applications. In this paper, distinct futures in the newly developed transformer protection and control system are presented.

The impact of communication message has not yet been effectively considered in the reliability assessment of the centralized protection system in smart substations. To address this issue, first, a method to evaluate the reliability of communication messages was proposed by analyzing the transmission mechanism of the communication message. Subsequently, based on the centralized protection system in D2-1-type smart substations, contrastive analysis focusing on the impact of messages on protection reliability under different networking modes and protection strategies was carried out. Finally, virtual local area network (VLAN) was applied to demonstrate its capability to improve the reliability of protective messages. The result shows that, the distributed protection is subject to the message reliability, whereas the centralized protection is not apparently affected by the message reliability. The reliability of protection systems is also impacted by different networking modes, and VLAN is conducive to improving the protection system reliability.

The article presents a comparative review and analysis of modern methods of functioning of relay protection systems of medium-voltage distribution networks with distributed generation sources (DGR). The analysis touched upon the main technical challenges associated with the active introduction of DGR, primarily renewable sources, into regional networks, which leads to a change in the directions of flows and currents in the network, violation of the conditions for ensuring selectivity, sensitivity and technically perfect coordination between protective devices. Special attention is paid to the features of relay protection of micro-power systems during the transition from network to island mode.The purpose of the study is to review and analyze modern methods and systems of relay protection of distribution regional networks with DRG, taking into account the features of their operation.The article studies traditional and innovative (adaptive, combined, based on sequential components, using phasor measuring devices and artificial intelligence) protection methods, their efficiency and ability to operate in characteristic modes. The comparative analysis was carried out taking into account known modern platforms, their advantages, complexity of implementation, requirements for communication channels, settings and tests, possible risks due to the complexity of relay protection systems. The key advantages and limitations of modern approaches to implementing relay protection, as well as current trends in the development of protection systems for active networks with a high share of DRG, are identified.It is shown that to ensure the reliability and safety of power supply in modern conditions, it is necessary to implement adaptive, intelligent and hybrid protection systems with the possibility of operating regional microgrids in island mode.As a rule, in distribution regional networks, protection systems based on current measurement are used, less often - based on voltage measurement or combined protection systems (based on current and voltage measurement). However, the change in the structure of power supply from centralized (with one-way current flow) to decentralized (with different DRGs) creates a serious threat to network protection systems in terms of reliability of operation, sensitivity and coordination of various protection elements.It is established that innovative methods demonstrate higher flexibility, accuracy and ability to self-organize. At the same time, they require more complex technical and software implementation, communication setup and relevant implementation experience. The reliability of protection in the future will be determined by the system's ability to adapt to rapid changes in operating mode, dynamic connection and change of DRG parameters, requirements for power supply of critical consumers even in the event of a transition to islanding modes when disconnected from the main grid.

The protection system in electrical engineering is a crucial component in maintaining electrical reliability. The protection system is a vital component that needs attention. Its utility not only serves as a parameter for the reliability of the electrical system but also as a safeguard for electrical system devices, starting from power suppliers (Power Plants), interconnection networks, transmission networks, to distribution networks. In Indonesia, with the unique dynamics of the domestic market, periodic evaluation of relays becomes important. This study investigates the current status and dominance of relay usage in Indonesia. Using a literature study method, we broadly identify the functions, utilities, and applications of Over Current Relay (OCR), Ground Fault Relay (GFR), Differential Relay, and Reverse Power Relay in Indonesia's electrical system. This literature study outlines several types of relays in Indonesia and their dominant usage in the electrical system, providing insights for readers and institutions using relays in Indonesia's electrical system. The implications of this literature study are to broaden the knowledge of the authors and readers and to encourage continuous innovation. With an understanding of the types of relays in Indonesia's electrical system, strategic steps can be taken to improve the reliability and efficiency of the electrical protection system in Indonesia.

This paper presents the results of a survey on the reliability of protective systems for power transformers that serves at distribution substations of the CHEC system. The protective systems of seventeen 115/33 kV power transformers in the range of 20 to 60 MVA and twenty-six 33/13.2 kV power transformers in the range of 3 to 30 MVA were surveyed using operating records that covers 7 years. Reliability indexes were computed for the protective systems as a whole and for their components and the models of arrival of false openings and their corresponding repairs were obtained. Results show that: i. Security is the weakest aspect of the studied protective systems, being false openings the more frequent problem. ii. Failure to close is the second more frequent problem of the studied protective systems. iii. Circuit breakers are the protective system component that require more attention because they cause most of false openings and failures to close and have the highest repair time. iv. Arrival of false openings and their times to repair are stationary what means reliability of studied protective systems is not deteriorating. v. Reliability indexes of the protective systems for 115/33 kV power transformers is higher than the ones of the 33/13.2 kV power transformers.

Knowledge transfer in system modeling and its realization through an optimal allocation of information granularity

Modern cyberattacks are the most powerful disturbance factor for computer networks, as they have a complex and devastating impact. The impact of cyberattacks is primarily aimed at disrupting the performance of computer network protection means. Therefore, managing this defense system in the face of cyberattacks is an important task. The paper examines a technique for constructing an effective control system for a computer network security system operating in real time in the context of cyber attacks. It is supposed that it is built on the basis of constructing a system state space and a stack of control decisions. The probability of finding the security system in certain state at each control step is calculated using a finite Markov chain. The technique makes it possible to predict the number of iterations for managing the security system when exposed to cyber attacks, depending on the segment of the space of its states and the selected number of transitions, as well as automatically generate control decisions. An algorithm has been developed for situational control of a computer network security system in conditions of cyber attacks. The experimental results obtained using the generated dataset demonstrated the high efficiency of the developed technique and the ability to use it to determine the parameters that are most susceptible to abnormal deviations during the impact of cyber attacks.

This paper presents a distributed multiagent scheme to detect and identify cyber threats on the protection systems of power grids. The integration of information and communication technologies into existing power grids builds critical cyber-physical energy systems, in which digital relays are networked cyber-physical components subject to various cyber threats. Cyber attacks on protection systems may mimic real faults, cause component failure, and disable the communication links. Agents utilize both cyber and physical properties to reinforce the detection technique and further distinguish cyber attacks from physical faults. This paper also introduces the problem of secure communication protocols and highlights the comparative studies for enhancing the security of the protection systems. The proposed scheme is validated using a benchmark power system under various fault and cyber attack scenarios.

Power system automation and communication standards are spearheading the power system transition towards a smart grid. IEC 61850 is one such standard, which is widely used for substation automation and protection. It enables real-time communication and data exchange between critical substation automation and protection devices within digital substations. However, IEC 61850 is not cyber secure. In this paper, we demonstrate the dangerous implications of not securing IEC 61850 standard. Cyber attacks may exploit the vulnerabilities of the Sampled Values (SV) and Generic Object-Oriented Substation Event (GOOSE) protocols of IEC 61850. The cyber attacks may be realised by injecting spoofed SV and GOOSE data frames into the substation communication network at the bay level. We demonstrate that such cyber attacks may lead to obstruction or tripping of multiple protective relays. Coordinated cyber attacks against the protection system in digital substations may cause generation and line disconnections, triggering cascading failures in the power grid. This may eventually result in a partial or complete blackout. The attack model, impact on system dynamics and cascading failures are veri ed experimentally through a proposed cyber-physical experimental framework that closely resembles real-world conditions within a digital substation, including Intelligent Electronic Devices (IEDs) and protection schemes. It is implemented through Hardware-in-the-Loop (HIL) simulations of commercial relays with a Real-Time Digital Simulator (RTDS).

In software reliability modeling, the parameters of the model are typically estimated from the test data of the corresponding component. However, the widely used point estimators are subject to random variations in the data, resulting in uncertainties in these estimated parameters. Ignoring the parameter uncertainty can result in grossly underestimating the uncertainty in the total system reliability. This paper attempts to study and quantify the uncertainties in the software reliability modeling of a single component with correlated parameters and in a large system with numerous components. Another characteristic challenge in software testing and reliability is the lack of available failure data from a single test, which often makes modeling difficult. This lack of data poses a bigger challenge in the uncertainty analysis of the software reliability modeling. To overcome this challenge, this paper proposes utilizing experts' opinions and historical data from previous projects to complement the small number of observations to quantify the uncertainties. This is done by combining the maximum-entropy principle (MEP) into the Bayesian approach. This paper further considers the uncertainty analysis at the system level, which contains multiple components, each with its respective model/parameter/ uncertainty, by using a Monte Carlo approach. Some examples with different modeling approaches (NHPP, Markov, Graph theory) are illustrated to show the generality and effectiveness of the proposed approach. Furthermore, we illustrate how the proposed approach for considering the uncertainties in various components improves a large-scale system reliability model.