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Time filter

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Brisbane, Australia

Ingram D.M.E.,Queensland University of Technology | Schaub P.,QGC Pty Ltd. | Taylor R.R.,Queensland University of Technology | Campbell D.A.,Queensland University of Technology
IEEE Transactions on Power Delivery | Year: 2014

The IEC 61850 family of standards for substation communication systems was released in the early 2000s and includes IEC 61850-8-1 and IEC 61850-9-2 that enable Ethernet to be used for process-level connections between transmission substation switchyards and control rooms. This paper presents an investigation of process bus protection performance, since the inservice behavior of multifunction process buses is largely unknown. An experimental approach was adopted that used a Real Time Digital Simulator and 'live' substation automation devices. The effect of sampling synchronization error and network traffic on transformer differential protection performance was assessed and compared to conventional hard-wired connections. Ethernet was used for all sampled value measurements, circuit breaker tripping, transformer tap-changer position reports, and precision time protocol synchronization of sampled value merging unit sampling. Test results showed that the protection relay under investigation operated correctly with process bus network traffic approaching 100% capacity. The protection system was not adversely affected by synchronizing errors significantly larger than the standards permit, suggesting that these requirements may be overly conservative. This 'closed loop' approach, using substation automation hardware, validated the operation of protection relays under extreme conditions. Digital connections using a single shared Ethernet network outperformed conventional hard-wired solutions. © 1986-2012 IEEE. Source


Ingram D.M.E.,Queensland University of Technology | Schaub P.,QGC Pty Ltd. | Campbell D.A.,Queensland University of Technology | Taylor R.R.,Queensland University of Technology
IEEE Transactions on Instrumentation and Measurement | Year: 2013

New substation automation applications, such as sampled value (SV) process buses and synchrophasors, require a sampling accuracy of 1 \mu\hbox{s} or better. The Precision Time Protocol (PTP), IEEE Std. 1588, achieves this level of performance and integrates well into Ethernet-based substation networks. This paper takes a systematic approach to the performance evaluation of commercially available PTP devices (grandmaster, slave, transparent, and boundary clocks) from a variety of manufacturers. The 'error budget' is set by the performance requirements of each application. The 'expenditure' of this error budget by each component is valuable information for a system designer. The component information is used to design a synchronization system that meets the overall functional requirements. The quantitative performance data presented show that this testing is effective and informative. Results from testing PTP performance in the presence of SV process bus traffic demonstrate the benefit of a 'bottom-up' component testing approach combined with 'top-down' system verification tests. A test method that uses a precision Ethernet capture card, rather than dedicated PTP test sets, to determine the correction field error of transparent clocks is presented. This test is particularly relevant for highly loaded Ethernet networks with stringent timing requirements. The methods presented can be used for development purposes by manufacturers or by system integrators for acceptance testing. An SV process bus was used as the test application for the systematic approach described in this paper. The test approach was applied, components were selected, and the system performance was verified to meet the application's requirements. Systematic testing, as presented in this paper, is applicable to a range of industries that use, rather than develop, PTP for time transfer. © 1963-2012 IEEE. Source


Ingram D.M.E.,Queensland University of Technology | Schaub P.,QGC Pty Ltd. | Campbell D.A.,Queensland University of Technology | Taylor R.R.,Queensland University of Technology
IEEE Transactions on Instrumentation and Measurement | Year: 2013

Advanced substation applications, such as synchrophasors and IEC 61850-9-2 sampled value process buses, depend upon highly accurate synchronizing signals for correct operation. The IEEE 1588 Precision Timing Protocol (PTP) is the recommended means of providing precise timing for future substations. This paper presents a quantitative assessment of PTP reliability using fault tree analysis. Two network topologies are proposed that use grandmaster clocks with dual network connections and take advantage of the best master clock algorithm (BMCA) from IEEE 1588. The cross-connected grandmaster topology doubles reliability, and the addition of a shared third grandmaster gives a nine-fold improvement over duplicated grandmasters. The performance of BMCA mediated handover of the grandmaster role during contingencies in the timing system was evaluated experimentally. The 1 μs performance requirement of sampled values and synchrophasors are met, even during network or GPS antenna outages. Slave clocks are shown to synchronize to the backup grandmaster in response to degraded performance or loss of the main grandmaster. Slave disturbances are less than 350 ns provided the grandmaster reference clocks are not offset from one another. A clear understanding of PTP reliability and the factors that affect availability will encourage the adoption of PTP for substation time synchronization. © 1963-2012 IEEE. Source


Ingram D.M.E.,Queensland University of Technology | Schaub P.,QGC Pty Ltd. | Taylor R.R.,Queensland University of Technology | Campbell D.A.,Queensland University of Technology
IEEE Transactions on Industrial Electronics | Year: 2013

New substation technology, such as nonconventional instrument transformers, and a need to reduce design and construction costs are driving the adoption of Ethernet-based digital process bus networks for high-voltage substations. Protection and control applications can share a process bus, making more efficient use of the network infrastructure. This paper classifies and defines performance requirements for the protocols used in a process bus on the basis of application. These include Generic Object Oriented Substation Event, Simple Network Management Protocol, and Sampled Values (SVs). A method, based on the Multiple Spanning Tree Protocol (MSTP) and virtual local area networks, is presented that separates management and monitoring traffic from the rest of the process bus. A quantitative investigation of the interaction between various protocols used in a process bus is described. These tests also validate the effectiveness of the MSTP-based traffic segregation method. While this paper focuses on a substation automation network, the results are applicable to other real-time industrial networks that implement multiple protocols. High-volume SV data and time-critical circuit breaker tripping commands do not interact on a full-duplex switched Ethernet network, even under very high network load conditions. This enables an efficient digital network to replace a large number of conventional analog connections between control rooms and high-voltage switchyards. © 1982-2012 IEEE. Source


Ingram D.M.E.,Queensland University of Technology | Schaub P.,QGC Pty Ltd. | Taylor R.R.,Queensland University of Technology | Campbell D.A.,Queensland University of Technology
IEEE Transactions on Industrial Informatics | Year: 2013

Process bus networks are the next stage in the evolution of substation design, bringing digital technology to the high-voltage switchyard. Benefits of process buses include facilitating the use of nonconventional instrument transformers, improved disturbance recording and phasor measurement, and the removal of costly, and potentially hazardous, copper cabling from substation switchyards and control rooms. This paper examines the role a process bus plays in an IEC 61850-based substation automation system. Measurements taken from a process bus substation are used to develop an understanding of the network characteristics of 'whole of substation' process buses. The concept of 'coherent transmission' is presented, and the impact of this on Ethernet switches is examined. Experiments based on substation observations are used to investigate in detail the behavior of Ethernet switches with sampled value traffic. Test methods that can be used to assess the adequacy of a network are proposed, and examples of the application and interpretation of these tests are provided. Once sampled value frames are queued by an Ethernet switch, the additional delay incurred by subsequent switches is minimal, and this allows their use in switchyards to further reduce communications cabling, without significantly impacting operation. The performance and reliability of a process bus network operating close to the theoretical maximum number of digital sampling units (merging units or electronic instrument transformers) was investigated with networking equipment from several vendors and has been demonstrated to be acceptable. © 2005-2012 IEEE. Source

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