Abstract-At the core of the development of "Smart Transmission Grids" is the design, implementation, and testing of synchronized phasor measurement data applications that can supplement Wide-Area Monitoring, Protection, and Control Systems (WAMPAC). Nevertheless, the development of new PMU data-based WAMPAC applications has been relatively slow. The great potential of WAMPAC systems is being limited by this, and efforts are needed so that new applications can be developed. The slow rate of development of these applications is strongly related to, among other factors, the application development approach used. This article starts by discussing the needs and approaches for developing WAMPAC applications that exploit synchronized phasor measurements, and illustrates how one of these approaches has been achieved. A preliminary work carried out to develop and implement a Smart Transmission System Laboratory (SmarTS Lab), a hardware and softwarebased system for developing and analyzing "Smart Transmission Grids" paradigms and applications for WAMPAC systems, are described. The laboratory's conceptual architecture and hardware and software implementation are presented, and some of its components are described. Finally, the article illustrates proofof-concept examples of how PMU data-based applications can be developed.

A power system is vulnerable to faults, either due to natural disasters or by misoperation of the system due to operators' negligence. This can result in permanent damage to power system components leading to considerable costs for their replacement and in longer disconnections of power supply to customers, which is highly undesirable. This sets a requirement for a power system to sustain faults, while protection systems should minimize the damage in important components and the effect of faults as much as possible. This is achieved by using power system protection techniques and methodologies [1]. Microprocessor-based relays have their own algorithms for monitoring the power system through current and voltage inputs from CTs and VTs respectively. Protection relays are thoroughly tested using relay test sets to confirm their reliability and safe operation before commis sioning them in a substation. With the advent of RTS and compact reconfigurable I/O controllers , large power systems can be simulated and their behavior can be analyzed in both steady state and faulted conditions. Based on this analysis, protection system and power system controllers can be developed for more efficient, reliable and safe operation of power systems. RTS are cur rently being used for HIT.., validation, developing algorithms for adaptive protection, designing system integrity protection schemes (SIPS), remedial action schemes (RAS) and other applications [2]. In this paper, a detailed model for overcurrent relays is provided. To assess the performance of this model a test system is designed in SPS and is simulated in RT using Opal RT's eMEGAsim real-time simulator. Once the SIL model is certified, it is further validated by HIL simulation using the overcurrent protection function of Schweitzer Engineering Laboratories (SEL) relay SEL-487E. The results obtained by the SIT.., and the HIL are compared. SPS does not have a dedicated library for protection functions. Therefore it is necessary to validate the model with HIL so that the validated software model can be used for accurate representation of power system protection components. Similar approach for protection relay model validation has been demonstrated in [3] [4] using different modeling platform and RTS. The remainder of the paper is arranged as follows. Section II offers a literature review on overcurrent relays. Section III presents the details of the overcurrent relay modelled in SPS. Section IV focuses on the design of test system in SPS and incorporation of proposed relay model in the test case. SIL simulation and results are discussed in Section V, while standalone testing and HIL validation is explained in Section VI. Finally in Section VII, conclusions are drawn and future work is outlined. II. O VERCURRENT R ELAYSAs the name states, an overcurrent relay provides protection against over currents. This relay uses current inputs from a CT and compares the measured values with preset values. Figure 1 shows the logical representation of an overcurrent relay. If the input c...

Abstract-Synchronized phasor measurement units (PMUs) provide GPS-time tagged high-sampling rate positive-sequence voltage and current phasors. When placed in high-voltage substations in power networks, PMUs can provide real-time information that is necessary for the development of Smart Transmission Grid software applications for improving power system monitoring, control and protection. The development of these applications, particularly for use within control centers for on-line purposes, is limited by the availability of and access to real-time PMU data and other information. One attractive approach for application development is the use of real-time simulators to which PMUs can be interfaced as hardware-in-the-loop (HIL) devices to harvest PMU data. However, this approach has technical and economical limitations, which can be tackled by the virtualization of PMU devices. This article describes the development of an entirely software-based synchronized phasor measurement unit for use within real-time simulators that will allow the emulation of a large number of real-life PMUs, which in turn can be used for creating new phasor-based applications.

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