As future power systems become increasingly complex and interconnected to other energy carriers, a single research infrastructure can rarely provide the required test-beds to study a complete energy system, especially if different types of real power hardware are expected to be in-the-loop. Therefore, virtual interconnection of laboratories for large-scale systems plays an important role for geographically distributed real-time simulation. This paper presents the improvements made in simulation fidelity as well as usability for establishing future simulator and laboratory connections. A general procedure is proposed and analyzed for geographically distributed real-time simulation, which allows users easily to adapt this system to specific test cases. A systematic and comprehensive analysis of dynamic phasor based co-simulation interface algorithm and its improvements are provided to demonstrate the advantages as well as limitations of this approach.
This paper presents an approach to extend the capabilities of smart grid laboratories through the concept of Power Hardware-in-the-Loop (PHiL) testing by re-purposing existing grid-forming converters. A simple and cost-effective power interface, paired with a remotely located Digital Real-time Simulator (DRTS), facilitates Geographically Distributed Power Hardware Loop (GD-PHiL) in a quasi-static operating regime. In this study, a DRTS simulator was interfaced via the public internet with a grid-forming ship-to-shore converter located in a smart-grid testing laboratory, approximately 40 km away from the simulator. A case study based on the IEEE 13-bus distribution network, an on-load-tap-changer (OLTC) controller and a controllable load in the laboratory demonstrated the feasibility of such a setup. A simple compensation method applicable to this multi-rate setup is proposed and evaluated. Experimental results indicate that this compensation method significantly enhances the voltage response, whereas the conservation of energy at the coupling point still poses a challenge. Findings also show that, due to inherent limitations of the converter’s Modbus interface, a separate measurement setup is preferable. This can help achieve higher measurement fidelity, while simultaneously increasing the loop rate of the PHiL setup.
The increasing complexity of power systems has warranted the development of geographically distributed real-time simulations (GD-RTS). However, the wide scale adoption of GD-RTS remains a challenge owing to the (i) limitations of state-of-the-art interfaces in reproducing faster dynamics and transients, (ii) lack of an approach to ensure a successful implementation within geographically separated research infrastructures, and (iii) lack of established evidence of its appropriateness for smart grid applications. To address the limitations in reproducing of faster dynamics and transients, this paper presents a synchronous reference frame interface for GD-RTS. By means of a comprehensive performance characterization (application agnostic and application oriented), the superior performance of the proposed interface in terms of accuracy (reduced error on average by 60\% and faster settling times) and computational complexity has been established. This paper further derives the transfer function models for GD-RTS with interface characteristics for analytical stability analysis that ensure stable implementations avoiding the risks associated with multiple RI implementations. Finally, to establish confidence in the proposed interface and to investigate GD-RTS applicability for real-world applications, a GD-RTS implementation between two RIs at the University of Strathclyde is realized to demonstrate inertial support within transmission network model of the Great Britain power system.
Novel concepts enabling a resilient future power system and their subsequent experimental evaluation are experiencing a steadily growing challenge: large scale complexity and questionable scalability. The requirements on a research infrastructure (RI) to cope with the trends of such a dynamic system therefore grow in size, diversity and costs, making the feasibility of rigorous advancements questionable by a single RI. Analysis of large scale system complexity has been made possible by the real-time coupling of geographically separated RIs undertaking geographically distributed simulations (GDS), the concept of which brings the equipment, models and expertise of independent RIs, in combination, to optimally address the challenge. This paper presents the outputs of IEEE PES Task Force on Interfacing Techniques for Simulation Tools towards standardization of GDS as a concept. First, the taxonomy for setups utilized for GDS is established followed by a comprehensive overview of the advancements in real-time couplings reported in literature. The overview encompasses fundamental technological design considerations for GDS. The paper further presents four application oriented case studies (real-world implementations) where GDS setups have been utilized, demonstrating their practicality and potential in enabling the analysis of future complex power systems.