Sustainable Energy, Grids and Networks 2 (2015) 41–50 Contents lists available at ScienceDirect Sustainable Energy, Grids and Networks journal homepage: www.elsevier.com/locate/segan Simulation and testing of the over-current protection system based on IEC 61850 Process-Buses and dynamic estimator Ahmed Abdolkhalig ∗ , Rastko Zivanovic School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, Australia article info Article history: Received 5 September 2014 Received in revised form 16 April 2015 Accepted 17 April 2015 Available online 22 April 2015 Keywords: IEC 61850 Process-Bus Sampled Measured Values Kalman filter Digital over-current relay abstract This paper presents a successful real-time simulation and testing of the over-current protection system based on IEC 61850-9-2 Sampled Measured Values communication and a dynamic estimator using a simulator of the real-time environment. The TrueTime software and the Matlab Simulink had been integrated into the real-time environment simulator for testing real-time performance of the IEC 61850 Process-Bus and the protection system. Performance of the IEC 61850 Process-Bus communications can be affected by many factors like, bandwidth and cable length. These factors will affect the measurements provided to protective relays through Process-Bus due to delay or loss of some Sampled Measured Values. The purpose of the tests in the real-time environment simulator is to show how an over-current protection relay would react to operation conditions of the IEC 61850 Process-Bus. Understanding how a physical protection system can respond to IEC 61850 Process-Bus communication will give engineers the confidence that is needed to assure that the system under consideration will behave as acceptable. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction In real-time power system studies, real-time simulators are needed for testing real-time performance of protection and control devices. In this paper, we propose use of a cost-effective alternative to real-time simulators which is the real-time environment simulator [1]. For testing the protective relay performance in real- time, the measurement signals (i.e. voltage or current) will be provided as IEC 61850-9-2 Sampled Measured Values (SMVs) to the relay in real-time as well as sending trip and reclose signals. Those signals depend on the communication system operating conditions and we are particularly interested in the impact of the communication latency and loss of samples. Since the real-time environment simulators have the capability to simulate various communication conditions [1], the performance of any protection and control device in real-time can be evaluated. In the proposed testing simulator, IEC 61850-9-2 Sampled Measured Values (SMVs) [2] sent by a Merging Unit (MU) can be applied as voltage and current signals to a digital relay instead of using the traditional analogue values. SMVs are data link layer protocol. However, still they suffer from two important delays ∗ Corresponding author. E-mail addresses: ahmed.abdolkhalig@adelaide.edu.au (A. Abdolkhalig), rastko@eleceng.adelaide.edu.au (R. Zivanovic). i.e. propagation delay and transmission delay. The propagation delay which depends on the difference (i.e. distance) between source and end node while the transmission delay is the amount of time required to push all of the packet’s bits into the physical medium. Although the transmission delay can play a role in evaluating the performance of digital relay, it has been neglected in this study due to the fact that its value is very small compared to the propagation delay. According to the standard, for protection applications, the transmission time of the IEC 61850-9-2 SMV message should be less than 3 ms. The MU is an IEC 61850 device that is used to generate SMVs resulting from the transducers at bay-level and is sending them as the IEC 61850-9-2 messages over the Process-Bus which is Ethernet-based. Messages sent by MUs contain up to 8 signals of current and voltage (i.e. signals per phase and neutral). The SMVs defined in two standardized sample rates with one sample rate equals 80 samples per cycle for basic protection and control, and the other has a high rate of 256 samples per cycle for power quality and measurements. Ethernet-based technology can offer a data rate up to 10 gbps with the physical mediums such as coaxial cable, twisted pair or optical Fiber. The communication over the wired Ethernet- based technology has been standardized as IEEE 802.3 [3]. The first Ethernet-based technology used a copper co-axial or a twisted pair cable to provide a data rate up to 10 Mbps, then later; the optical Fiber (100BASE-BX10) was able to achieve a data rate up to 100 Mbps speed. Currently, Fiber-optic based on IEEE 802.3 can http://dx.doi.org/10.1016/j.segan.2015.04.001 2352-4677/© 2015 Elsevier Ltd. All rights reserved.