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Geographically distributed simulations (GDS) overcome the inherent limitations in capabilities of single research infrastructure to accurately represent large-scale complex power and energy systems within representative operating environments in real-time. The feasibility of GDS has been proven, however, there is a lack of confidence in its adoption owing to limited evidence of its stability and accuracy that ascertain its practical applicability. This paper presents detailed small signal stability models for GDS setups with two interface signals transformations. The models have been validated by empirical analysis and used for determining the boundaries for stable operation of GDS setups. For the common region of stability of the two transformations considered, accuracy analysis presented offers insights for their selection. This advancement, thereby, enables realisation of experimental setups that can cater for the growing need to design and validate operational schemes that ensure robust and resilient operation of critical national infrastructure.

Low-inertia operation of small-scale power systems, such as a microgrid or a portion of a long feeder, requires careful coordination of the controller performance of the constituting devices. This challenge is exacerbated in microgrids serving the functionalities of a conventional synchronous-based generation unit while comprised of smaller DERs operating mainly interfaced through power electronics converters. This paper builds on the idea of set point modulation and proposes a two-level control strategy that aims to achieve superior performance at the point of common coupling (PCC) of microgrids by combining a local control level with a distributed and coordinated level. Several case studies on both AC and DC systems, the CIGRE low-voltage benchmark system as the AC system and a test DC microgrid, validate the performance of the proposed approach. The real-world applicability of the approach is established via a high-fidelity power hardware-in-the-loop (PHIL) experimental setup and an application case study on grid frequency regulation. The proposed approach enables a microgrid to participate in ancillary service provisions where speed and quality of regulation are critical.

This paper proposes a new Coordinated Voltage Control (CVC) method with Reactive Power Management Scheme (RPMS) for a Hybrid Micro-grid (MG). The CVC scheme, based on synchronizing the response speeds of different voltage regulating devices, is coordinated with a novel Reactive Power Management Scheme (RPMS). Two cases, with and without proposed CVC, were simulated in the PSCAD/EMTDC environment and compared against each other. The case with proposed CVC shows superior performance, when tested for fault triggered islanding, intentional islanding and MG internal fault. Further, the proposed CVC with RPMS is compared to a voltage regulation method present in literature. The proposed CVC with RPMS provides better voltage regulation, maximizes the fast dynamic reactive power reserve, and improves the transient response and transient stability margin of the Hybrid Micro-Grid.

Grid-forming converter establishes a stable and controllable voltage at its output terminal without requiring external angle reference, which enables the GFC to be a candidate for providing black start services. However, this attribute poses significant challenges to the conventional power hardware-in-the-loop (PHIL) simulation, which incorporates the physical power converter by regulating its voltage angle to be synchronized with that of an interfacing power amplifier mimicking the real-time emulated power grid. The lack of voltage synchronization at the coupling point of GFC and interfacing power amplifier leads to instability. To address this challenge, the current-type interfacing method with compensation and scaling scheme is proposed to interface a GFC with soft black-start capability into a PHIL setup. Analytical assessment and experimental results involving interfacing a 90 kVA power converter implemented with grid-forming control are presented to verify the methodology.

This report summarizes the work conducted within ERIGrid related to an integrated simulation environment for large-scale systems.The main goal of the JRA2 is to develop advanced simulation-based tools and methods to validate Smart Grid scenarios, configurations and applications in con-text of co-simulation. The work done in D-JRA2.1 involved assessment of specialized simulation packages for Smart Grids and to develop tools to couple these simulation packages for co-simulation. New tools and models were also developed as some of the existing tools were not sufficient enough to achieve the appropriate couplings. In D-JRA2.2 co-simulation-based assessment methods were developed to compare the performance between monolithic and co-simulations. In D-JRA2.3 we aim to combine all the work done under WP JRA2 to present an integrated simulation package that can be applied to Large Scale systems. The assessment methods developed in D-JRA2.2 have been tested initially in small systems to measure the performance and identify possible flaws. How-ever, the complexity increases significantly in large scale realistic systems. This report documents the challenges faced when the systems and their models grow larger (i.e., upscaled) and how different large scale specific phenomena and issues were identified. After the identification of the challenges, the assessment methods were modified and packaged into an in-tegrated simulation environment which can be used for scaled out systems. The simulation pack-ages are provided as an addendum along with this report while their details are concisely docu-mented in this report.