Integrated Simulation Model of Power System Protection Schemes and Process Bus Communication Networks André dos Santos a , Bruno Soares, Fan Chen R&D NESTER Sacavém, Portugal a andre.santos@ren.pt Martijn Kuipers b , Sérgio Sabino b , António Grilo c , Paulo Pereira c , Mário Nunes c , Augusto Casaca c b INOV, c INESC-ID & INOV Lisboa, Portugal Abstract—An integrated simulation model of power system protection schemes and IEC 61850 process bus communication models was developed for the design of substation automation systems of the future. The model is capable of reproducing a sequence of the relevant events and equipment states under different operation scenarios, including normal operation and power system fault disturbances. The model includes a description of the power system, the protection scheme, including its several intelligent electronic devices, and the process bus communication network. The model allows an assessment of the functional correctness of steady-state operation of the protection scheme as well as during a power system fault clearance process. It also allows the performance evaluation of the underlying communication network. The capabilities of the model are illustrated with an example scenario of power system fault followed by circuit breaker failure. Keywords—Substation automation system, Process Bus, Protection scheme, Integrated Simulation. I. INTRODUCTION The foreseen substation automation systems (SAS) to be used in transmission and distribution networks in the future will be designed to fully support the IEC 61850 communication standard [1]. This comprehends combined use of intelligent electronic devices (IED) and a local area network (LAN) to implement protection automation and control (PAC) functions and additionally monitoring functions. Typical LAN network architectures used in substations comprehend two segregated networks, the first named station bus is used by SAS functions for alarming, signaling and maintenance; the second, named process bus, is used by the most critical functions such as tripping and blocking. The IEC standard specifies communication system requirements for the communication network operating under any power system condition and SAS state, i.e. during failure and repair stages of IED and communication devices. The This work was supported by CEPRI (Chinese Electric Power Research Institute), in the scope of the R&D Nester (Centro de Investigação em Energia REN-SGCC, SA) project “Substation of the Future”. requirements include failure conditions, redundancy design, recovery times and message transfer time. Accordingly, for designing the SAS, in view of all these requirements, the combination of different studies is required, namely conducting reliability studies [2, 3] and dynamic performance studies [4-7]. Furthermore, some of the studies may require the combination of different domains for analyzing the mutual impact between domains. This may include simulation, emulation and testing real systems. Concerning simulation, the SAS may either be modeled in a given simulation environment [9] or split in different environments [10] by means of joint and synchronized simulation, allowing to benefit from using the most appropriate models from each simulation environment. Typically, this concerns the combined simulation of power systems and information and communication technology (ICT) systems using Distributed Computer Simulation Systems compliant with the IEEE std. 1516 – High Level [11]. A comprehensive overview of various simulation environments and their characteristics aiming at performing combined power systems and communication network simulation has been published by Mets et al. [12]. Most of the application examples overviewed in the study have been applied to wide-area monitoring, protection, control and demand side response, showing the wide application spectrum of combined simulation in power systems. As per the use of integrated simulation for SAS studies, IED 61850-based and communication equipment models are usually developed for substation communication network performance, such as for comparison studies of LAN topologies, ring versus star [5], or to validate the adequacy of new proposed LAN architectures concerning maximum transfer time defined in the IEC 61850 standard [6]. As per the use of combined simulation for SAS studies, special simulation environments and IEC61850 based models are developed, enabling to run a combined simulation of power systems and communication networks for analyzing the