Tarkan ja luotettavan ajan siirto kantaverkossa

This master’s thesis is about time distribution that supports substation applications needed for power transmission. The work was done for the Telecommunication department of Finland’s power transmission system operator Fingrid Oyj. This thesis answers to the following question: What is the need for accurate and synchronized time in power substations and how it will be delivered? Fingrid’s telecommunication network supports the power transmission grid and its operation. Telecommunication network can distribute time to power substations for the applications that need synchronized and accurate time. Current telecommunication equipment used in Fingrid is getting old and new techniques are planned to be implemented. When Fingrid is acquiring new communication equipment, they need to set requirements on the capability to distribute time. This thesis is an initial effort to investigate time distribution requirements for Fingrid’s needs. This thesis aids Fingrid Telecommunication department to define requirements for time distribution. For this thesis, I met with multiple Fingrid professionals, telecommunication device suppliers and time distribution researchers. This thesis answers to its research questions by means of a literature review and interviews.Tämä diplomityö käsittelee ajansiirron vaikutusta sähköasemasovellusten toimintaan. Työ tehtiin Suomen kantaverkkoyhtiö Fingrid Oyj:n tietoliikenneyksikölle. Fingridin tietoliikenneverkko on osa kantaverkkoa ja mahdollistaa sähköjärjestelmän toiminteita. Tietoliikenneverkon yksi palvelu on synkronoidun ajan siirtäminen sähköasemille. Nykyinen tietoliikennetekniikka on vanhenemassa ja uutta laitteistoa suunnitellaan hankittavaksi ja testattavaksi. Tämän diplomityön tarkoitus on selvittää mikä on järkevä tapa toteuttaa ajan siirto ja kuinka tarkkaa sen pitää olla. Työ auttaa tietoliikenneyksikköä hankinnan vaatimusmäärittelyssä ajansiirron osalta. Työtä varten on tavattu monia Fingridin asiantuntijoita, tietoliikennelaitetoimittajia sekä ajansiirron asiantuntijoita. Työ vastaa tutkimuskysymykseen kirjallisuuskatsauksen ja haastattelujen perusteella

Study and Design of Inter-Range Instrumentation Group Time Code B Synchronization of IEC 61850 Sampled Values

Distribution substations are an important part of a chain which delivers energy from power production to customers. They transform the voltage level from transmission levels, usually 35kV and up, to distribution levels ranging between 600 and 35000 V. Recent developments in the instrument transformer field have been toward low-power solutions which use digital measurement values called sampled values in place of analog voltages and currents in substations. The IEC 61850-9-2 standard and its implementation guideline 9-2 LE by the UCA international users group define an interface for sampled values. This interface is used between an IED and LPIT. The main requirement of using sampled values is accurate time synchronization in order to prevent phase misalignment resulting in unnecessary protection function tripping. 9-2 LE defines two methods for synchronization: 1PPS and PTP. Today, PTP is widely used in the western markets, but due to costs associated with PTP-capable GPS clocks and Ethernet switches as well as vendor inoperability problems, some markets are hesitant to take into use. The purpose of this thesis is to propose a solution to this problem: use IRIG-B as a synchronization method in a PTP grandmaster. This paper discusses the differences between these two time synchronization topologies, associated costs, disturbance handling, accuracy and it also discusses the design of IRIG-B to PTP conversion done in a bay-level device. The device acts as a PTP grandmaster but the source comes from an IRIG-B clock instead of a GPS PTP grandmaster clock. The results shown in this thesis demonstrate that using IRIG-B as a main or redundant source in synchronization of sampled values is a more cost-effective option, especially if the station is to be retrofitted with sampled values configuration. The proposed bay level device also maintains the desired accuracy levels of ±1 µs set by IEC 61850-5.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Time Synchronization Solution for FPGA-based Distributed Network Monitoring

Distributed network monitoring solutions face various challenges with the increase of line speed, the extending variety of protocols, and new services with complex KPIs. This paper addresses one part of the first challenge: faster line speed necessitates time-stamping with higher granularity and higher precision than ever. Proper, system-wide time-stamping is inevitable for network monitoring and traffic analysis point of view. It is hard to find feasible time synchronization solutions for those systems that have nation-wide, physically distributed probes. Current networking equipment reside in server rooms, and have many legacy nodes. Access to GPS signal is complicated in these places, and Precision Time Protocol (PTP) does not seem to be supported by all network nodes in the near future – so high precision time-stamping is indeed a current problem. This paper suggests a novel, practical solution to overcome the obstacles. The core idea is that in real-life, distributed network monitoring systems operate with a few, finite number of probeclusters, and their site should have a precise clock provided by PTP or GPS somewhere in the building. The distribution of time information within a site is still troublesome, even within a server rack. This paper presents a closed control loop solution implemented in an FPGA-based device in order to minimize the jitter, and compensate the calculated delay

S3E: A Large-scale Multimodal Dataset for Collaborative SLAM

With the advanced request to employ a team of robots to perform a task collaboratively, the research community has become increasingly interested in collaborative simultaneous localization and mapping. Unfortunately, existing datasets are limited in the scale and variation of the collaborative trajectories, even though generalization between inter-trajectories among different agents is crucial to the overall viability of collaborative tasks. To help align the research community's contributions with realistic multiagent ordinated SLAM problems, we propose S3E, a large-scale multimodal dataset captured by a fleet of unmanned ground vehicles along four designed collaborative trajectory paradigms. S3E consists of 7 outdoor and 5 indoor sequences that each exceed 200 seconds, consisting of well temporal synchronized and spatial calibrated high-frequency IMU, high-quality stereo camera, and 360 degree LiDAR data. Crucially, our effort exceeds previous attempts regarding dataset size, scene variability, and complexity. It has 4x as much average recording time as the pioneering EuRoC dataset. We also provide careful dataset analysis as well as baselines for collaborative SLAM and single counterparts. Data and more up-to-date details are found at https://github.com/PengYu-Team/S3E

Організація мережі розповсюдження часу за протоколом РТР (ІЕЕЕ 1588)

Метою даної роботи є дослідження питань розповсюдження часу за протоколом РТР. PTP, також відомий як IEEE 1588, є протоколом точної синхронізації часу, що функціонує по мережі Ethernet. Висока точність синхронізації кінцевих пристроїв за часом досягається завдяки проставлення міток часу на апаратному рівні і розрахунку часових затримок проходження повідомлень синхронізації часу через пристрої мережі.The purpose of this work is to study the issues of time distribution according to the RTR protocol. PTP, also known as IEEE 1588, is a precise time synchronization protocol that operates over an Ethernet network. High accuracy of synchronization of end devices in time is achieved by affixing timestamps at the hardware level and calculating time delays for the passage of time synchronization messages through network devices

A Survey of Clock Synchronization Over Packet-Switched Networks

Clock synchronization is a prerequisite for the realization of emerging applications in various domains such as industrial automation and the intelligent power grid. This paper surveys the standardized protocols and technologies for providing synchronization of devices connected by packet-switched networks. A review of synchronization impairments and the state-of-the-art mechanisms to improve the synchronization accuracy is then presented. Providing microsecond to sub-microsecond synchronization accuracy under the presence of asymmetric delays in a cost-effective manner is a challenging problem, and still an open issue in many application scenarios. Further, security is of significant importance for systems where timing is critical. The security threats and solutions to protect exchanged synchronization messages are also discussed

The GOOSE Protocol

The majority of the electrical substations built today conform to the international standard IEC 61850 that uniformly defines the communication between the various intelligent electronic devices (IEDs) of the substation automation system. The success of the standard in substation automation has expanded its application to new areas, such as wind power, hydro power, and smart grids. For this thesis, the most intriguing use of the standard is its application to the communication between the control system of internal combustion engines and other equipment in a power plant. The main objective of this thesis is to gain early experience on the use of the Generic Object Oriented Substation Events (GOOSE) protocol, which is often considered the most prominent communication protocol of IEC 61850. In this thesis, the standard IEC 61850 is described, and its most fundamental concepts are illustrated by clear examples. An application based on open source software has been developed in the Linux-environment in conjunction with this thesis. The application enables two IEDs from different manufacturers to exchange GOOSE messages. The emphasis of the thesis is thus on the presentation of the GOOSE protocol and the developed application. The results show that the GOOSE protocol provides compatible interfaces for information exchange between IEDs provided by different manufacturers, and can be seen as a viable option as a future communication protocol. IEC 61850 will likely be put into service in engine power plants, in the near future. The schedule partially depends on the development of the markets and the requirements of the customers.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Time Sensitive Networking over 5G Networks

Time-Sensitive Networking (TSN IEEE 802.1Q), is an Ethernet technology that provides deterministic messaging on standard Ethernet. When centrally managed, the TSN technology offers the capability of guaranteed delivery of messages with reduced jitter. TSN uses time-scheduling in providing deterministic communications and works at Layer 2 (L2) of the Open System Interconnection. The advantage of TSN working at L2 is that TSN entities (switches and bridges) only need the information contained in Ethernet headers to make forwarding decisions. In addition, the information carried in Ethernet frame payloads does not have to be limited to IP only, making TSN applicable in industrial applications with different application payloads. The goal of the thesis was to come up with a state-of-the-art design of IEEE TSN modules. This goal involved designing a topology for testing TSN, prototyping the TSN modules, and testing the modules when completed. The thesis evaluates how the developed TSN module's performance compares to IEEE WG set standards. I carried out the experimentation based on the IEEE Working Group (WG) recommendations and publications which provided the necessary modifications to Precision Time Protocol version 2 (PTPv2) regarding packets that needed to be modified to develop generalized Precision Time Protocols (gPTP). Before entering and exiting the 5G System (5GS), the gPTP messages are changed. These encompass all the needed packet header modifications and necessary calculations to achieve the synchronization accuracies of 900 nanoseconds as stipulated by the IEEE 802.1AS standard. The project's findings were that the functionalities stipulated by the IEEE TSN WG were possible to implement and even achieve synchronization between the different TSN modules. The thesis did not accomplish the synchronization accuracy levels specified by the IEEE TSN. This low synchronization accuracy level was understandable, considering that the 5GS and equipment needed to improve performance were missing. The thesis evaluates the exactness with which gPTP packets arriving at the TSN modules could be detected, captured, modified, and sent to end stations successfully and provides an in-depth explanation for why the synchronization accuracy levels achieved were low

Time sensitive networking security: issues of precision time protocol and its implementation

Time Sensitive Networking (TSN) will be an integral component of industrial networking. Time synchronization in TSN is provided by the IEEE-1588, Precision Time Protocol (PTP) protocol. The standard, dating back to 2008, marginally addresses security aspects, notably not encompassing the frames designed for management purposes (Type Length Values or TLVs). In this work we show that the TLVs can be abused by an attacker to reconfigure, manipulate, or shut down time synchronization. The effects of such an attack can be serious, ranging from interruption of operations to actual unintended behavior of industrial devices, possibly resulting in physical damages or even harm to operators. The paper analyzes the root causes of this vulnerability, and provides concrete examples of attacks leveraging it to de-synchronize the clocks, showing that they can succeed with limited resources, realistically available to a malicious actor