Robb Wallen
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View article: Modeling and Power-Hardware-in-the-Loop Validation of Synchronous Wind: An Inverterless Grid-Forming Wind Power Plant: Preprint
Modeling and Power-Hardware-in-the-Loop Validation of Synchronous Wind: An Inverterless Grid-Forming Wind Power Plant: Preprint Open
Grid-forming (GFM) control of Type-3 and Type-4 wind turbine generators has attracted substantial attention in power systems research; however, the limited over-current capability of power electronics converters continues to deteriorate th…
View article: GFM Inverter Hardware Testing
GFM Inverter Hardware Testing Open
This presentence provides overview of NREL's testing capabilities and experience with advanced testing of multimegawatt grid-forming inverters.
View article: On the Low Risk of SSR in Type III Wind Turbines Operating With Grid-Forming Control
On the Low Risk of SSR in Type III Wind Turbines Operating With Grid-Forming Control Open
We have shown in previous work that the risk of subsynchronous resonance between wind power plants with Type III wind turbines and series-compensated transmission lines is low when the wind turbines are operated in grid-forming (GFM) mode …
View article: A Testing Framework for Grid-Forming Resources: Preprint
A Testing Framework for Grid-Forming Resources: Preprint Open
This paper presents a testing framework for grid-forming (GFM) resources. It first analytically derives in frequency domain the active and reactive power response of an ideal voltage source with a reactor. These transfer functions are then…
View article: NREL CGI and PHIL Platform for Validation of Multi-Technology Energy Systems at Scale
NREL CGI and PHIL Platform for Validation of Multi-Technology Energy Systems at Scale Open
The presentation is an update on National Renewable Energy Laboratory Flatirons Campus' capabilities around multi-megawatt grid simulation and power hardware-in-the-loop. Recent improvements in operational and dynamic range of existing 7MV…
View article: On the Low Risk of Subsynchronous Resonance (SSR) in Type III Wind Turbines Operating in Grid-Forming Control
On the Low Risk of Subsynchronous Resonance (SSR) in Type III Wind Turbines Operating in Grid-Forming Control Open
We have shown in a previous work that the risk of sub-synchronous resonance (SSR) between a wind power plant with Type III wind turbines and series-compensated transmission lines is low when the wind turbines in the plant are operated in g…
View article: Unleashing the Frequency: Multi-Megawatt Demonstration of 100% Renewable Power Systems with Decentralized Communication-Less Control Scheme
Unleashing the Frequency: Multi-Megawatt Demonstration of 100% Renewable Power Systems with Decentralized Communication-Less Control Scheme Open
Power systems, which range in size from small microgrids to island systems to large regional grids, are typically managed by a central controller that requires complex communication methods and can be unreliable and pose cyber security ris…
View article: Grid-Forming Wind Power
Grid-Forming Wind Power Open
This presentation is a summary of research conducted by NREL team in the area of developing and testing grid forming controls by wind power.
View article: SIW21-95: Hybridizing Synchronous Condensers with Grid-Forming Battery Energy Storage Systems
SIW21-95: Hybridizing Synchronous Condensers with Grid-Forming Battery Energy Storage Systems Open
One of the main challenges associated with deployment of high shares of inverter-based resources (IBRs) in power grid is not only reduced system inertia but also degrading system strength that may cause severe stability impacts. A minimum …
View article: Photovoltaic Plant and Battery Energy Storage System Integration at NREL's Flatirons Campus
Photovoltaic Plant and Battery Energy Storage System Integration at NREL's Flatirons Campus Open
Although utility-scale solar photovoltaic (PV) power plants are becoming a cost-effective energy resource, there is belief within the energy industry that the increasing penetrations of PV technologies could potentially impact grid reliabi…
View article: Sequence Impedance Measurement of Utility-Scale Wind Turbines and Inverters – Reference Frame, Frequency Coupling, and MIMO/SISO Forms
Sequence Impedance Measurement of Utility-Scale Wind Turbines and Inverters – Reference Frame, Frequency Coupling, and MIMO/SISO Forms Open
Sequence impedance responses with or without considering frequency coupling in both MIMO and SISO forms are increasingly used for the stability analysis of three-phase power electronic systems; however, many aspects of sequence impedance m…
View article: Control System Stability for Converter-Dominated Grids
Control System Stability for Converter-Dominated Grids Open
This presentation provides an overview of control system stability for converter-dominated electric grids.
View article: Measuring Commercial Wind Turbine Impedances for Stability Analysis
Measuring Commercial Wind Turbine Impedances for Stability Analysis Open
This presentation provides an overview of measuring commercial wind turbine impedances for stability analysis.
View article: Impedance Analysis and PHIL Demonstration of Reactive Power Oscillations in a Wind Power Plant Using a 4-MW Wind Turbine
Impedance Analysis and PHIL Demonstration of Reactive Power Oscillations in a Wind Power Plant Using a 4-MW Wind Turbine Open
This paper presents impedance-based analysis, mitigation, and power-hardware-in-the-loop (PHIL) demonstration of reactive power oscillations in a wind power plant using a 4-MW Type III wind turbine drivetrain. Because such low-frequency os…
View article: Ultrafast Frequency Response of Converter-Dominant Grids Using PMUs
Ultrafast Frequency Response of Converter-Dominant Grids Using PMUs Open
This presentation provides an overview of the ultrafast frequency response of converter-dominant grids using phasor measurement units.
View article: Impedance Measurement of Inverter-Coupled Generation Using a Multimegawatt Grid Simulator
Impedance Measurement of Inverter-Coupled Generation Using a Multimegawatt Grid Simulator Open
This presentation provides an overview of interver-coupled generation using a multimegawatt grid simulator.
View article: WGRID-49 GMLC Project Report: Understanding the Role of Short-Term Energy Storage and Large Motor Loads for Active Power Controls by Wind Power
WGRID-49 GMLC Project Report: Understanding the Role of Short-Term Energy Storage and Large Motor Loads for Active Power Controls by Wind Power Open
The GMLC project is built upon the results of pioneering research funded by the U.S. Department of Energy (DOE) and conducted by the National Renewable Energy Laboratory (NREL)—in collaboration with the Electric Power Research Institute an…
View article: Large-Signal Impedance-Based Modeling and Mitigation of Resonance of Converter-Grid Systems
Large-Signal Impedance-Based Modeling and Mitigation of Resonance of Converter-Grid Systems Open
Large-signal impedance of grid-connected converters can be used to predict resonance-generated distortions in converter-grid systems. Note that the large-signal impedance of a network represents its impedance response for different magnitu…
View article: Overview of CGI/Dynos/PHIL Platform
Overview of CGI/Dynos/PHIL Platform Open
This presentation highlights recent activities using the Controllable Grid Interface and dynamometers.
View article: Phase 1 Integrated Systems Test and Characterization Report for the 5-Megawatt Dynamometer and Controllable Grid Interface
Phase 1 Integrated Systems Test and Characterization Report for the 5-Megawatt Dynamometer and Controllable Grid Interface Open
This report details the commissioning of the 5-MW dynamometer and Controllable Grid Interface (CGI) at the National Wind Technology Center (NWTC) at the National Renewable Energy Laboratory (NREL). The purpose of these characterization tes…
View article: Gearbox Reliability Collaborative Phase 3 Gearbox 3 Test Report
Gearbox Reliability Collaborative Phase 3 Gearbox 3 Test Report Open
Many gearboxes in wind turbines do not achieve their expected design life; they do, however, commonly meet or exceed the design criteria specified in current standards in the gear, bearing, and wind turbine industry as well as third-party …
View article: Controllable Grid Interface for Testing Ancillary Service Controls and Fault Performance of Utility-Scale Wind Power Generation: Preprint
Controllable Grid Interface for Testing Ancillary Service Controls and Fault Performance of Utility-Scale Wind Power Generation: Preprint Open
The rapid expansion of wind power has led many transmission system operators to demand modern wind power plants to comply with strict interconnection requirements. Such requirements involve various aspects of wind power plant operation, in…
View article: Gearbox Reliability Collaborative Phase 3 Gearbox 3 Test Plan
Gearbox Reliability Collaborative Phase 3 Gearbox 3 Test Plan Open
This document describes the Phase 3 test plan for the Gearbox Reliability Collaborative Gearbox #3. The primary test objective is to measure the planetary load sharing characteristics in the same conditions as the original gearbox design. …
View article: Torsional Vibration in the National Wind Technology Center’s 2.5-Megawatt Dynamometer
Torsional Vibration in the National Wind Technology Center’s 2.5-Megawatt Dynamometer Open
This report documents the torsional drivetrain dynamics of the NWTC's 2.5-megawatt dynamometer as identified experimentally and as calculated using lumped parameter models using known inertia and stiffness parameters. The report is present…
View article: Characterizing the Influence of Abstraction in Full-Scale Wind Turbine Nacelle Testing
Characterizing the Influence of Abstraction in Full-Scale Wind Turbine Nacelle Testing Open
In recent years, there has been a growing interest in full-scale wind turbine nacelle testing to complement individual component testing. As a result, several wind turbine nacelle test benches have been built to perform such testing with t…
View article: Hardware-in-the-Loop Testing of Utility-Scale Wind Turbine Generators
Hardware-in-the-Loop Testing of Utility-Scale Wind Turbine Generators Open
Historically, wind turbine prototypes were tested in the field, which was--and continues to be--a slow and expensive process. As a result, wind turbine dynamometer facilities were developed to provide a more cost-effective alternative to f…