Assessing the reliability of SiC MOSFET through inverter-like accelerated test vs. power cycling test
Not Available
14 SOLAR ENERGY↗
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Validation of the Fault Ride-Through Response of a Generic EMT Inverter Model by Laboratory Testing
This paper presents the validation of the fault ride-through response of a large-scale inverter model using laboratory testing of a commercial inverter. First, we present the generic inverter model specifications. The generic inverter control is developed based on the fault ride-through response performance requirements of IEEE Std 2800-2022 for inverter-based resources. Next, we present laboratory tests that emulate voltages at the inverter terminal resulting from balanced and unbalanced faults on the transmission system. The tests are performed on a commercia12.2 MVA battery storage inverter at the U.S. National Renewable Energy Laboratory. Comparisons of the model's response to the laboratory measurements show the generic model presented can predict the controlled response of the commercial equipment. The differences between the model's response and the laboratory measurements during the initial transient at fault inception are discussed.
fault ride-through↗
Frequency Scans for GFM Performance Verification
This presentation shows how frequency scan tests of inverter-based resources can be used to define specifications for grid-forming (GFM) control.
grid simulator↗
Assessing the vulnerability of solar inverters to EMPs: Port testing, PCI modeling, and protection strategies
Renewable energy sources are becoming an ever-larger contributor to the power grid. These renewable energy sources depend upon the power electronic devices, specifically inverters, being essential for connecting Photovoltaic (PV) generation to the grid. However, the Electromagnetic Pulses (EMPs) caused by the high-altitude nuclear explosions can generate fast broad-band pulses with nanosecond rise time, potentially causing damage or destruction to electronic components. To assess the vulnerability of PV inverters to high-altitude EMPs, the port testing and Pulsed Current Injection (PCI) modeling schemes are proposed based on the port impedance analysis. Wide-band frequency measurements are achieved by fusing impedance results from three vector network analyzers. Then, a PCI model is used to simulate the induced response to EMP, with two typical immunity levels of EC5 and EC8 tested. Here, the experiment successfully excites the induced voltage and current under EMP, where the voltage and current can reach 1500V/40A and 8000V/150Aunder EC5 andEC8, respectively. The port vulnerability analysis results demonstrate that only some ports can survive under EC5. To defend against the impact of EMP, three protection strategies are discussed.
42 ENGINEERING↗
A Two-Stage Current Limiting Control Strategy for Direct-Droop-Controlled Grid-Forming Inverters
This paper presents a two-stage current limiting control strategy with fault ride-through capability for the direct-droop-controlled grid-forming (GFM) inverters. The proposed approach comprises Stage 1 and Stage 2 current limiting controls. During faults, Stage 1 current limiting control instantly clamps the inverter output current magnitude to its maximum transient limit by blocking the switching pulses to the insulated-gate bipolar transistors (IGBTs) with the help of a hysteresis loop control, and Stage 2 current limiting control limits the inverter output current magnitude to its steady-state limit by regulating the amplitude and frequency of the modulating waveform utilizing the active and reactive current limiting control loops. By implementing the current limiting actions in two stages, this approach can effectively limit the over-current within a few cycles after the fault occurrence and ensure synchronism to the grid after long-term fault events. The efficacy of the proposed control approach is validated through electromagnetic transient (EMT) simulation results conducted on a single GFM inverter-based test system and the IEEE 39-bus test system with multiple GFM inverters in the PSCAD platform.
Mohiuddin, Sheik Mohammad↗
Black Start with Inverter-Based Resources: Hardware Testing
Black start, or grid restoration after a wide-spread power outage, is a critical service on the power system that has historically been provided by transmission-connected synchronous generators. As the power system transitions to rely on more distributed and inverter-based resources it will be critical that these resources can also provide black start services. In this work we investigated battery energy storage and solar photovoltaics technical capabilities and limitations to provide black start services through hardware testing in an experimental microgrid testbed. This hardware demonstration of inverter-based resources providing black start functions can help inform grid operators on how to include these types of resources in their black start plans.
24 POWER TRANSMISSION AND DISTRIBUTION↗
Novel Approach to PV Inverter Modeling and Simulation Leveraging Experiments, Learning Based Modeling and Co-Simulation
Photovoltaic (PV) inverter manufacturers use custom, proprietary control approaches and topologies in their inverter design. The proprietary nature of these approaches makes it challenging to share electromagnetic transients (EMT) domain models for system studies. This research work presents an approach to develop EMT models from experimental data. We use novel approach in experimental design, high fidelity data collection, use of learning-based modeling, and co-simulation to reduce the time taken to develop an EMT model for an inverter under test (IUT). We used a 20 kW off-the-shelf grid following PV inverter and subjected the inverter to controlled tests. The tests include voltage and frequency step changes, as well as solar irradiance variations. The recorded high frequency data were used to train a neural network model representing the dynamic behavior of the IUT. The model was subsequently imported into an EMT tool using co-simulation techniques, and thus completing the modeling effort.
black box inverter modeling↗
Grid Forming Inverter: Laboratory-Scale Hardware Test Bed Setup and Weak Grid Operation
In recent times, the concept of grid forming inverters has gained popularity. Grid forming inverters have proven to be a promising alternative to the grid following inverters. In this paper, we present the hardware test bed implementation of grid forming inverter in islanding mode as well as in grid connected mode. The control structure includes inverter-level inner current control and outer voltage control, and plant-level P - f and Q - V droop control. The Q - V droop provides the voltage command, whereas P - f droop provides the frequency command and is also key for the synchronization process. While it is straightforward to set up the test bed for the islanded operation, it is a challenging process to set up the grid-forming inverter in the grid-connected mode. We present the key technologies and demonstrate the start-up process and weak grid operation using the hardware experiment results. Results from EMT model developed in MATLAB/SimPowerSystems are also presented for side-by-side comparison.
Mittal, Ratik↗
Testing GFM and GFL Inverters Operating With Synchronous Condensers
Inverter-based resources (IBRs) are quickly evolving into a source of reliability services to the electric grid. Penetration levels of variable generation are rapidly increasing, ranging from 60% -70% in some systems. To go further, a fundamental shift is required to address challenges associated with grid stability. Synchronous condensers (SCs) are considered an important complementary technology in such transitions. This paper provides one-of-a-kind insights into real experimental results from operating a real MW-scale system consisting of a 2.2-MVA grid-forming (GFM) and grid-following (GFL) battery energy storage system, 2.5-MVA SCs, and a 3-MVA load bank operating as a small, islanded grid. Challenges that are expected in larger systems were mimicked in this small but real system to demonstrate seamless transitions from one mode to another as well as stable operation with different combinations of GFM and GFM resources, including a "loss of last synchronous generator" case. The experimental results presented in this paper are a valuable resource to everyone involved in developing and validating models or developing controls of power systems consisting of inverters and synchronous condensers.
grid-following converter↗
Modeling Efficiency of Inverters with Multiple Inputs: Test Procedure for Measuring Efficiency.
Abstract not provided.
Hansen, Clifford W↗
MODELING INVERTERS WITH MULTIPLE INPUTS: TEST PROCEDURE FOR MEASURING EFFICIENCY.
Abstract not provided.
Hansen, Clifford W↗
Chapter 5: Advanced Characterization and Testing of Grid-Forming Resources
In order to compare and define grid-forming (GFM) resources' performance requirements, uniform test procedures are necessary to characterize these resources' capabilities to serve various system needs. Most tests performed on grid-following (GFL) inverters are also required for GFM inverters, with additional tests also needed specifically for GFM inverters. This section describes advanced characterization and testing methods for GFM inverters, with the goal of serving as a guide- line for developing test procedures.
grid-forming resources↗
Performance Evaluation and Loss Modeling of WBG Devices based on a Novel Double-Pulse Test Method for Current Source Inverter
Careful measurements of the power device characteristics are necessary to accurately estimate a power converter's losses and efficiency. The conventional double-pulse test (DPT) circuit is a well-known method to implement this laboratory characterization of power devices and power modules. However, the switching characteristics of a power device depend on the power electronics circuit in which it is connected as well as the power circuit's physical layout, in addition to the device's internal structure. Hence, the conventional DPT circuit configuration, which is tailored for a standard voltage-source inverter (VSI), is not well-suited for a current-source inverter (CSI). This paper demonstrates a previously-proposed CSI-based DPT measurement technique that is appropriate for normal CSI operation. The characteristics of SiC MOSFETs and series-connected SiC Schottky diodes used in a CSI are measured using this improved technique while taking temperature effects into account to yield more accurate loss predictions. The CSI losses, including the switching and conduction losses of SiC MOSFETs and SiC Schottky diodes, have been modeled using this approach. The total CSI losses and efficiency have been estimated based on the CSI DPT results and loss models.
42 ENGINEERING↗
Multiple Grid-Forming Inverters in Black-Start: The Challenges
Black-start is a major challenge toward the successful operation of an islanded inverter-based system. In this article, the technical challenges for the black-start of multiple grid-forming inverters are reported. Specifically, this article discusses inverter synchronization, voltage and frequency regulation, and power-sharing between the grid-forming inverters. Experiment results from a multi-inverter test-bed have been provided to support the discussion. Furthermore, a grid-forming inverter controller for black-start operation is developed and presented in this article that addresses the discussed technical challenges. The performance of the developed controller in black-start operation is verified through experiment results.
Sadeque, Fahmid↗
Large-Scale Inverter Integration in Bulk Power Grids Using Heterogeneous Grid-Forming Control Strategies
The conventional generation within the grid is gradually being replaced by inverter based resources. However, the integration of inverters into realistic transmission grid models has not been thoroughly explored. To address this gap, this work develops an automation framework aimed at facilitating the integration of a large number of inverter-based resources into a large-scale grid. Two types of grid-forming controlled inverters—namely droop-controlled inverters and virtual synchronous machine-controlled inverters—are developed for use in positive-sequence simulation packages. Various penetration levels ranging from 23% to 100% of grid-forming inverters are tested in a grid setup in the US Western Interconnection. The dynamic performance of inverters under different control schemes is compared in response to various disturbances.
Lyu, Xue [BATTELLE (PACIFIC NW LAB)]↗