Grid-Forming Inverter-based Wind Turbine Generators: Comprehensive Review, Comparative Analysis, and Recommendations

High penetration of wind power with conventional grid following controls for inverter-based wind turbine generators (WTGs) weakens the power grid, challenging the power system stability. Grid-forming (GFM) controls are emerging technologies that can address such stability issues. Numerous methodologies of GFM inverters have been developed in the literature; however, their applications for WTGs have not been thoroughly explored. As WTGs need to incorporate multiple control functions to operate reliably in different operational regions, the GFM control should be appropriately developed for the WTGs. This paper presents a review of GFM controls for WTGs, which covers the latest developments in GFM controls and includes multi-loop and single-loop GFM, virtual synchronous machine-based GFM, and virtual inertia control-based GFM. A comparison study for these GFM-based WTGs regarding normal and abnormal operating conditions together with black-start capability is then performed. The control parameters of these GFM types are properly designed and optimized to enable a fair comparison. In addition, the challenges of applying these GFM controls to wind turbines are discussed, which include the impact of DC-link voltage control strategy and the current saturation algorithm on the GFM control performance, black-start capability, and autonomous operation capability. Finally, recommendations and future developments of GFM-based wind turbines to increase the power system reliability are presented

Stability Considerations for a Synchronous Interconnection of the North American Eastern and Western Electric Grids

This paper presents some of the stability considerations for an ac interconnection of the North American Eastern and Western electric grids. Except for a brief time around 1970, the North American Eastern and Western grids have operated asynchronously, with only small power transfers possible through a few back-to-back HVDC ties. This paper provides results from a study showing that an ac interconnection may be possible with only modest changes to the existing transmission grid. The paper’s main focus is on the dynamic aspects of such an interconnection. The paper also shows how newer visualization techniques can be leveraged to show the results of larger-scale, long duration dynamic simulations. Results are given for a 110,000-bus model of the actual North American electric grid and an 82,000-bus synthetic grid

PowerSimulationsDynamics.jl -- An Open Source Modeling Package for Modern Power Systems with Inverter-Based Resources

The inclusion of inverter-based resources from renewable energy creates new challenges for the stability and transient behavior of power systems which are best understood by studying their dynamic responses through simulation. In this paper, we develop an open source simulation toolbox, PowerSimulationDynamics.jl, to study the dynamic response of a balanced system with high penetration of inverter-based resources. PowerSimulationDynamics.jl is implemented in the Julia language and features a rich library of synchronous generator components and inverter models. In addition, it allows the study of both quasi-static phasors that employ an admittance matrix representation for the network and electromagnetic dq models that use a dynamic representation of the network. Case studies and validation exercises show that PowerSimulationDynamics.jl results closely match Quasi-Static Phasor (QSP) tools like Siemens PSSe, ANDES, and wave-form Electro-magnetic Transient (EMT) simulations like PSCA

Electromagnetic Transient-Transient Stability Hybrid Simulation for Electric Power Systems with Converter Interfaced Generation

abstract: With the increasing penetration of converter interfaced renewable generation into power systems, the structure and behavior of the power system is changing, catalyzing alterations and enhancements in modeling and simulation methods. This work puts forth a Hybrid Electromagnetic Transient-Transient Stability simulation method implemented using MATLAB and Simulink, to study power electronic based power systems. Hybrid Simulation enables detailed, accurate modeling, along with fast, efficient simulation, on account of the Electromagnetic Transient (EMT) and Transient Stability (TS) simulations respectively. A critical component of hybrid simulation is the interaction between the EMT and TS simulators, established through a well-defined interface technique, which has been explored in detail. This research focuses on the boundary conditions and interaction between the two simulation models for optimum accuracy and computational efficiency. A case study has been carried out employing the proposed hybrid simulation method. The test case used is the IEEE 9-bus system, modified to integrate it with a solar PV plant. The validation of the hybrid model with the benchmark full EMT model, along with the analysis of the accuracy and efficiency, has been performed. The steady-state and transient analysis results demonstrate that the performance of the hybrid simulation method is competent. The hybrid simulation technique suitably captures accuracy of EMT simulation and efficiency of TS simulation, therefore adequately representing the behavior of power systems with high penetration of converter interfaced generation.Dissertation/ThesisMasters Thesis Electrical Engineering 201