Superconducting fault current limiters (SFCLs) may play an important role in power-dense electrical systems. Therefore, it is important to understand the dynamic characteristics of SFCLs. This will allow the behavior of multiple SFCLs in a system to be fully understood during faults and other transient conditions, which will consequently permit the coordination of the SFCL devices to ensure that only the device(s) closest to the fault location will operate. It will also allow SFCL behavior and impact to be taken into account when coordinating network protection systems. This paper demonstrates that resistive SFCLs have an inverse current-time characteristic: they will quench (become resistive) in a time that inversely depends upon the initial fault current magnitude. The timescales are shown to be much shorter than those typical for inverse overcurrent protection. A generic equation has been derived which allows the quench time to be estimated for a given prospective fault current magnitude and initial superconductor temperature, and for various superconducting device and material properties. This information will be of value to system designers in understanding the impact of SFCLs on network protection systems during faults, and planning the relative positions of multiple SFCLs.

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This paper explores the potential future need for fault current er system, and some of the technical implications of this change. It is estimated that approximately 300-400 distribution substations will require fault current limitation, based on the statistical analysis of the projected (or violation). The analysis uses a UK electrical system scenario that satisfies the 2 emissions by 2050. A case study involving the connection of distributed generation (DG) via a superconducting fault current limiter (SFCL) is used to illustrate the potential protection and control issues. In particular, DG fault ride-through, autoreclosure schemes, and transformer inrush current can be problematic for SFCLs that require a recovery period. The potential solutions to these issues are discussed, such as the use of islanding or automation to reduce the fault level.

Communications is becoming increasingly important to the operation of protection and control schemes. Although offering many benefits, using standards-based communications, particularly IEC 61850, in the course of the research and development of novel schemes can be complex. This paper describes an open source platform which enables the rapid-prototyping of communications-enhanced schemes. The platform automatically generates the data model and communications code required for an Intelligent Electronic Device (IED) to implement publisher-subscriber Generic Object-Oriented Substation Event (GOOSE) and Sampled Value (SV) messaging. The generated code is tailored to a particular System Configuration Description (SCD) file, and is therefore extremely efficient at run-time. It is shown how a model-centric tool, such as the open source Eclipse Modeling Framework, can be used to manage the complexity of the IEC 61850 standard, by providing a framework for validating SCD files and by automating parts of the code generation process. The flexibility and convenience of the platform is demonstrated through a prototype of a real-time, fast-acting load shedding scheme for a low-voltage microgrid network. The platform is the first open source implementation of IEC 61850 which is suitable for real-time applications such as protection, and is therefore readily available for research and education.

Distributed control and optimization strategies are a promising alternative approach to centralized control within microgrids. In this paper, a multi-agent system is developed to deal with the distributed secondary control of islanded microgrids. Two main challenges are identified in the coordination of a microgrid: (i) interoperability among equipment from different vendors; and (ii) online re-configuration of the network in the case of alteration of topology. To cope with these challenges, the agents are designed to communicate with physical devices via the industrial standard IEC 61850 and incorporate a plug and play feature. This allows interoperability within a microgrid at agent layer as well as allows for online re-configuration upon topology alteration. A test case of distributed frequency control of islanded microgrid with various scenarios was conducted to validate the operation of proposed approach under controller and power hardware-in-the-loop environment, comprising prototypical hardware agent systems and realistic communications network.