Parallel Redundancy Protocol Research Articles

Laboratorial Implementation of Future Intelligent Transmission Network Substation for Smart Grid

This paper presents the future intelligent transmission network substation architecture; it identifies the most important design patterns for the purpose of building simplified versions of the communication infrastructure with High-Availability Seamless Redundancy (HSR) and Parallel Redundancy Protocol (PRP) configurations, respectively. The network model used for the laboratory tests is detailed, and details regarding the modelling of current-transformer (CT) saturation are given and discussed. Several intentional communications related to equipment or fibre failures are discussed. The laboratory setup for both HSR and PRP is presented. A real-time digital simulator (RTDS) network model is built and the test processes are presented. Some tests are carried out to test the functionality and interoperability with different fault conditions under the future intelligent transmission network substation architectures’ HSR-only and PRP-only data network configurations. The results are analysed and discussed, and a future intelligent transmission network substation test platform is successfully implemented in the laboratory. The experimental results can provide valuable information for power utilities and manufacturers to optimise substation architecture and their products under different conditions.

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.

Parallel Redundancy Protocol for Railway Wireless Data Communication Network

In order to solve the problem that the railway application services have strict requirements on the reliability, delay, and other indicators of mobile data communication, a parallel redundancy protocol for the railway wireless data communication network is proposed. By introducing a redundancy adaptation layer into the standard TCP/IP model, multi-link parallel data transmission is realized and transparent to the network layer and above. Transmitting multiple copies of the same packet through different paths makes the application systems have redundant communication capability without changing the existing data transmission mode. At the same time, according to the requirements of the receiving entity for redundant data elimination, an improved Bloom filter is proposed. By expanding the bit array and using the countdown mechanism, the elements in the data set can be dynamically inserted, deleted, and retrieved over time. Theoretical analysis and test results show that the proposed protocol can meet the requirements of data transmission between the on-board and trackside equipment and has the characteristics of simple deployment, high reliability, and high stability. Compared to using a single transmission link, the packet loss rate from field test can be reduced by 39.67% at the maximum, and the throughput and end-to-end data transmission delay are also significantly improved. The test in this paper also shows that the additional delay introduced is a maximum of 5.07 μs, which will not significantly affect the data transmission performance.

An Effective Communication Prototype for Time-Critical IIoT Manufacturing Factories Using Zero-Loss Redundancy Protocols, Time-Sensitive Networking, and Edge-Computing in an Industry 4.0 Environment

The Industrial Internet of things (IIoT), the implementation of IoT in the industrial sector, requires a deterministic, real-time, and low-latency communication response for its time-critical applications. A delayed response in such applications could be life-threatening or result in significant losses for manufacturing plants. Although several measures in the likes of predictive maintenance are being put in place to prevent errors and guarantee high network availability, unforeseen failures of physical components are almost inevitable. Our research contribution is to design an efficient communication prototype, entirely based on internet protocol (IP) that combines state-of-the-art communication computing technologies principles to deliver a more stable industrial communication network. We use time-sensitive networking (TSN) and edge computing to increase the determinism of IIoT networks, and we reduce latency with zero-loss redundancy protocols that ensure the sustainability of IIoT networks with smooth recovery in case of unplanned outages. Combining these technologies altogether brings more effectiveness to communication networks than implementing standalone systems. Our study results develop two experimental IP-based industrial network communication prototypes in an intra-domain transmission scenario: the first one is based on the parallel zero-loss redundancy protocol (PRP) and the second one using the high-availability seamless zero-loss redundancy protocol (HSR). We also highlight the benefits of utilizing our communication prototypes to build robust industrial IP communication networks with high network availability and low latency as opposed to conventional communication networks running on seldom redundancy protocols such as Media Redundancy Protocol (MRP) or Rapid Spanning Tree Protocol (RSTP) with single-point of failure and delayed recovery time. While our two network communication prototypes—HSR and PRP—offer zero-loss recovery time in case of a single network failure, our PRP communication prototype goes a step further by providing an effective redundancy scheme against multiple link failures.

Real-Time Performance and Security of IEC 61850 Process Bus Communications

Modern power-network communications are based on the IEC 61850 series standards. In this paper, we investigate the real-time performance and the vulnerabilities and attack scenarios at the sensor level communication networks more precisely on Sampled Measured Value protocol. The approach jointly evaluates the communication protocol, network topology and impact on electrical protection functions. We test the practical feasibility of the attacks on an experimental workbench using real devices in a hardware-in-the-loop setup. The tests are conducted on the two high-availability automation networks currently used in IEC 61850 process bus communications: Parallel Redundancy Protocol (PRP) and High-availability Seamless Redundancy (HSR)

Reliability provision in software defined power substations communication networks

In past years, the growing complexity of the electrical system and the rise in the number of Intelligent Electronic Devices (IEDs) have increased the data network management complexity in power substations. A pressing need to improve the reliability of such environments has pushed energy companies to increase the investment in the operation of their communication networks. This paper proposes to use the Software Defined Networking (SDN) paradigm into the communication networks of power substations to implement novel redundancy techniques based on redundant multicast trees, in order to replace the traditional redundancy mechanisms in power substation communication networks resulting in capital and operational costs reduction. We apply pre-planned protection based on redundant trees and formulate an Integer Linear Programming (ILP) model to provide redundant multicast trees in the network trying to minimize the number of used network links. Redundant trees transmit duplicate traffic under the same underlying LAN in isolation, to guarantee zero recovery time and improve the use of network resources. Simulation results show that our approach achieves the same performance as traditional redundancy mechanisms using half of the network resources (i.e., compared against the Parallel Redundancy Protocol, PRP).

Design Application and Research of Substation Comprehensive Automation System Based on Smart Grid

This paper analyses the needs of smart grids for smart substation automation systems, studies and proposes a new scheme for smart substation automation systems, which applies vertical integration of intervals to reduce the implementation of protection and monitoring functions, improve system reliability and ease of maintenance; Adopting network parallel redundancy protocol to improve the reliability and standardization of information transmission in the station; applying service-oriented monitoring function to improve the level of information sharing and coordination and interaction between substations and control centres. The key technology of the system is expounded, and its application prospect is prospected. Finally, the discussion and analysis of some problems that may exist when the system is popularized and applied.

Packet Duplication in Dual Connectivity Enabled 5G Wireless Networks: Overview and Challenges

Enabling ultra-reliable low-latency communications in 5G wireless networks creates challenging design requirements, particularly on the air interface. The stringent latency and reliability targets require enhancements at different layers of the protocol stack. On the other hand, the Parallel Redundancy Protocol, wherein each data packet is duplicated and transmitted concurrently over two independent networks, provides a simple solution for improving reliability and reducing latency in wireless networks. PRP can be realized in cellular networks through the dual connectivity solution. Recently, 3GPP has introduced packet duplication functionality in 5G wireless networks. To this end, this article provides an overview of the packet duplication functionality in 5G in light of recent developments within 3GPP, and also highlights the related technical challenges.

Smart Sensor: SoC Architecture for the Industrial Internet of Things

Nowadays, the concept of intelligent manufacturing is being introduced, based on the integration of new advanced technologies, such as the Internet of Things (IoT), distributed control, data analysis, and cyber-security in the manufacturing area, with the aim of improving manufacturing processes and the articles produced. In this sense, new intelligent devices (Smart Sensors) should be developed that integrate several detection methods (sensors), real-time (RT) data analysis, and wired and/or wireless connectivity. The main contribution of this paper is the design, implementation, and experimental verification of an architecture of a Smart Sensor that satisfies the operational requirements needed by the Industrial IoT (IIoT). Considering the software and hardware adaptability that a Smart Sensor should have, this paper takes advantage of the characteristics of the current field programmable gate arrays (FPGAs) and SoC to implement a Smart Sensor for the IIoT. In this sense, the proposed Smart Sensor architecture incorporates RT operation features, the ability to perform local data analysis, high availability communication interfaces, such as high-availability seamless redundancy (HSR) and parallel redundancy protocol (PRP), interoperability (industrial protocols), and cyber-security. The architecture was implemented with hardware available in the market, IP cores, and Python libraries developed by third parties. Finally, to validate the applicability of the architecture in the industry, two test environments were implemented. In the first case, interoperability, high availability, synchronization, and local data processing are validated. The second case aims to determine the delay when adding encryption (cyber-security) in layer 2 communications.

Redundant Communication Architectures: How They Benefit the Oil and Gas Industry

The International Electrotechnical Commission (IEC) Standard 61850 has become firmly established for substation automation. However, it is now also more than just an Ethernet-based protocol. Now in its second edition, the protocol has expanded into additional power supply areas because it defines the engineering process, data and service models, the conformity test, and all of the communication functions for substations. In doing so, the range of applications for protection devices is expanded. Multifunction devices are designed to protect, automate, measure, and monitor high- and medium-voltage networks. The standard enables using data from devices produced by different manufacturers. Additionally, redundant data transmission within the grid is standardized. To implement such solutions, there are two new Ethernet redundancy protocols: the Parallel Redundancy Protocol (PRP) and high-availability seamless redundancy (HSR), and these protocols were designed for mission- and time-critical applications in which communication interruptions or delays must not occur. Both protocols comply with IEC Standard 62439-3 for high-availability industrial Ethernet communication networks. PRP and HSR allow systems to continue operating even in the event of a malfunction because a communication path remains in place between the two protection devices even if a network fault occurs. This is especially important in sectors such as the oil and gas (O&G) industry to help prevent system outages. This article outlines some redundancy architectures and the benefits they offer the O&G industry.

Analyzing Reliability of the Communication for Secure and Highly Available GOOSE-Based Logic Selectivity

In an electrical distribution network, Logic Selectivity significantly reduces both the number and duration of outages. Generic Object-Oriented Substation Events (GOOSE) have a key role in the decision-making process of substation protection devices using GOOSE-based Logic Selectivity. GOOSE messages are exchanged between remote protection devices over the communication network. Secured communication with low latency and high reliability is therefore required in order to ensure reliable operation as well as meeting real-time requirement of the Logic Selectivity application. There is thus a need to evaluate feasibility of the selected communication network technology for Logic Selectivity use cases. This paper analyzes reliability of cellular 4G/LTE Internet for GOOSE communication in a Logic Selectivity application. For this purpose, experimental lab set-ups are introduced for different configurations: ordinary GOOSE communication, secured GOOSE communication by IPsec in Transport mode, and redundant GOOSE communication using the IEC 62439-3 Parallel Redundancy Protocol. In each configuration, the GOOSE retransmissions are recorded for a period of three days and the average GOOSE transmission time is measured. Furthermore, the measured data is classified into histograms and a probability value for communication reliability, based on the transmission time, is calculated. The statistical analysis shows that 4G Internet satisfies the real-time and reliability requirements for secure and highly available GOOSE-based Logic Selectivity.

Availability analysis of power substation automation architectures with PRP and HSR protocols

Industrial automation has been widely used in electric power substations. In this context, the IEC 61850 standard provides for the utilisation of redundancy in the data link layer to increase frame reception probability. This study aims to evaluate the availability of two power substation automation architectures based on the IEC 62439-3 standard, which describes two redundancy protocols named parallel redundancy protocol (PRP) and high-availability seamless redundancy (HSR). The authors evaluate both architectures using either PRP or HSR protocol against using no redundancy protocols. The reliability block diagram method has been used, and afterwards, the mean time to failure and availability have been calculated. Results show that the utilisation of redundancy protocols allied to the repair during the mission allows classifying the architectures in the higher availability class according to CEI IEC 870-4.

Cybersecurity for shared infrastructure substation networks with IEC 61850 GOOSE and Sampled Values

This study explains an example where select digital technologies are included to face the challenges related to cybersecurity in a windfarm solution. The network is planned, designed and commissioned by one operator, and will be maintained by two operators – one for generation assets for the windfarm, the other for the grid connection power transmission assets. The topology deployed is shown at a high level, describing how the windfarm offshore and onshore networks will be divided between the operators and the specific requirements of the solution. A more detailed view of the network is shown depicting Ethernet switches, routers and Intelligent Electronic Devices (IEDs); with the services and protocols used are explained and aligned with the challenges that each one represents in terms of cybersecurity, for example interconnections that use Parallel Redundancy Protocol for redundancy exchanging GOOSE interlocking. Each challenge is addressed one at the time and the topology will evolve as the solutions are added, going from a unified network under the control of one operator into two that can be easily split between operators.

Assessment and analysis of different process bus redundancy networks performance for IEC61850‐based digital substation

To achieve a highly reliable data communication network, Future Intelligent Transmission Network Substation (FITNESS) project has considered three different substation data communication redundancy networks. These include two independent parallel star networks, High-availability Seamless Redundancy (HSR) network, and Parallel Redundancy Protocol (PRP) network. This paper presents the assessment and comparison analysis of the data flow performance for these three networks. A typical 275 kV substation with the consideration of three redundancy networks is modelled and simulated using OPNET a communication network simulation tool. The data flow capability performance with respect of the network time delay for the typical protection and control equipment requirements (e.g. IEDs and MUs) in one bay are simulated and analysed. Results show that two independent parallel star networks have the highest data flow capacity. The capacity of PRP network is reduced by a half, while the capacity of HSR network is reduced to a quarter. The results also reveal that Ethernet Switch can consume a part of network bandwidth as well. The work would help power utilities to determine an optimal number of devices to be installed and to ensure highly reliable data communication network for protection and control functions in an IEC 61850 based digital substation. .

Cyber-Physical Production System Gateway Based on a Programmable SoC Platform

The communication needs of the different stages of production proposed in the new industrial generation (INDUSTRY 4.0), demand devices that can handle high availability protocols. This paper presents an architecture of a cyber physical production system gateway that can be implemented in an SoC, integrating high availability communication interfaces as the high-availability seamless redundancy/ parallel redundancy protocol (HSR/PRP), industrial ethernet communication interfaces (e.g. Profinet), and connections to sensors and actuators (e.g. Modbus series). Considering the software and hardware adaptability that the architecture should have, field programmable gate array and reconfigurable devices, in general, are considered as the best options for implementation, since the architecture requires high levels of hardware and software flexibility. The proposed architecture was validated in an experimental environment that is implemented utilizing electronic design automation tools, IP cores, and Python libraries developed by third parties is presented, to achieve a device which handles high availability communication HSR/PRP, Profinet, Profibus, and Modbus.

IPRP—The Parallel Redundancy Protocol for IP Networks: Protocol Design and Operation

Reliable packet delivery within stringent delay constraints is of paramount importance to mission-critical computer applications with hard real-time constraints. Because retransmission and coding techniques counteract the delay requirements, reliability may be achieved through replication over multiple fail-independent paths. The existing solutions, such as the parallel redundancy protocol (PRP), replicate all packets at the media access control layer over parallel paths. PRP works best in local area networks; however, it is not viable for IP networks that are a key element of emerging mission-critical systems. This limitation, coupled with diagnostic inability and lack of security, renders PRP unsuitable for reliable data delivery in these IP networks. To address this issue, we present a transport-layer solution: the IP parallel redundancy protocol (iPRP). Designing iPRP poses nontrivial challenges in the form of selective packet-replication, and soft-state and multicast support. iPRP replicates only time-critical unicast or multicast user datagram protocol traffic. iPRP requires no modifications to the existing monitoring application, end-device operating system, or to the intermediate network devices. It only requires a simple software installation on the end devices. iPRP has a set of diagnostic tools for network debugging. With our implementation of iPRP in Linux, we show that iPRP supports multiple flows with minimal processing-and-delay overhead. It is being installed in our campus smart-grid network and is publicly available.

Interoperability Performance Assessment of Multivendor IEC61850 Process Bus

Substations are increasingly reliant on devices compatible with IEC61850 standards. However, the conformity of a device with the standards does not necessarily guarantee interoperability with devices from different manufacturers. The use of devices compatible with IEC61850 standards presents a challenge to many system integrators, especially due to a lack of familiarity with features, such as generic object-oriented substation event, reporting, sample values, and the need for system redundancy. To facilitate a smooth implementation, all of the features and the data exchanges between devices need to be tested to ensure the system operates correctly. It is important to determine the compatibility of the devices made by different manufacturers. This paper presents a technique to assess the performance of merging units from different manufacturers, when operating with intelligent electronic devices, performing a distance protection function. The performance of the process bus with a parallel redundancy protocol is evaluated using a closed-loop approach involving a real-time digital simulator.

A novel PRP based deterministic, redundant and resilient IEC 61850 substation communication architecture

A secure, reliable, redundant, resilient, time critical, efficient and interoperable substation communication network (SCN) is a prerequisite for a viable Substation Automation System (SAS). Due to emergence of IEC 61850 as a global standard for substation automation, the interoperability issues among components of substation from different vendors are resolved. The communication network must be fault tolerant and any substantial levels of disturbances should not affect the normal operation of the SAS. Due to digitization in SCN, the communication methodology is mainly focused on exchange of encrypted packet information. Failure of the communication mechanism, even for the order of milliseconds, would lead to catastrophic effects within the substation and also impacts the operation of grid, if not cleared timely. The high reliability of such a system is only possible under a redundant communication network which has a zero switchover time. Hence IEC 62439-3 based redundant protocols such as Parallel Redundancy Protocol (PRP) recommended to be used in SCNs to achieve redundancy and seamless recovery in case of a failure. PRP based SAS along with detailed analysis of underlying process for implementing PRP protocol and its comparison with existing conventional protocols based SCN reported in literature is presented.

Using OpenFlow to control redundant paths in wireless networks

The deployment of wireless networks in critical industrial environments must ensure the availability of monitoring and control applications, for which it is essential to exploit redundancy techniques. In order to reduce to zero the failover time, in this paper, the Parallel Redundancy Protocol (PRP) is used in Wireless Local Area Networks (WLAN) which are implemented under the Software-Defined Networking (SDN) paradigm. It is discussed how the OpenFlow protocol allows an external controller to configure redundant paths between dual-homed devices. As a result, critical services can be protected in interference and mobility situations. The improvement in availability has been obtained by using both emulation and simulation.

Developing a New HSR Switching Node (SwitchBox) for Improving Traffic Performance in HSR Networks

High availability is crucial for industrial Ethernet networks as well as Ethernet-based control systems such as automation networks and substation automation systems (SAS). Since standard Ethernet does not support fault tolerance capability, the high availability of Ethernet networks can be increased by using redundancy protocols. Various redundancy protocols for Ethernet networks have been developed and standardized, such as rapid spanning tree protocol (RSTP), media redundancy protocol (MRP), parallel redundancy protocol (PRP), high-availability seamless redundancy (HSR) and others. RSTP and MRP have switchover delay drawbacks. PRP provides zero recovery time, but requires a duplicate network infrastructure. HSR operation is similar to PRP, but HSR uses a single network. However, the standard HSR protocol is mainly applied to ring-based topologies and generates excessively unnecessary redundant traffic in the network. In this paper, we develop a new switching node for the HSR protocol, called SwitchBox, which is used in HSR networks in order to support any network topology and significantly reduce redundant network traffic, including unicast, multicast and broadcast traffic, compared with standard HSR. By using the SwitchBox, HSR not only provides seamless communications with zero switchover time in case of failure, but it is also easily applied to any network topology and significantly reduces unnecessary redundant traffic in HSR networks.