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At least 397 records · Page 22

Scenario Creation and Power-Conditioning Strategies for Operating Power Grids with Two-Stage Stochastic Economic Dispatch

A significant difficulty associated with the use of stochastic programming to solve optimal power flow problems on a 5-minute timescale is the quality of renewable energy scenarios input by the user. This is especially true when considering power systems with high penetrations of renewable energy, e.g. wind power. This paper introduces the use of stochastic programming to solve the DC optimal power flow problem with scenarios drawn directly from high-fidelity data sets. Hence, the proposed method avoids the problem of lost physics by finding high-fidelity analogs that can describe future states of the system. Furthermore, this method can be simply extended to output multi-period scenarios to the stochastic program. We demonstrate the effectiveness of this technique by simulating dispatch operations on a synthetic test system over the course of a week.

94 GMLC - Grid Modernization Laboratory Consortium↗

On Distribution Grid Optimal Power Flow Development and Integration

Due to changes in electric distribution grid operation, new operation regimes have been recommended. Distribution grid optimal power flow (DOPF) has received tremendous attention in the research community, yet it has not been fully adopted across the utility industry. Our paper recognizes this problem and suggests a development and integration procedure for DOPF. We propose development of DOPF as a three step procedure of 1) processing the grid, 2) obtaining a tractable solution, and 3) implementing multiple solution algorithms and benchmarking them to improve application reliability. For the integration of DOPF, we demonstrate how a DOPF federate may be developed that can be integrated in a co-simulation environment to mimic the real-world conditions and hence improve its practicality to be deployed in the field. To demonstrate the efficacy of the proposed methods, tests on IEEE 123 bus system are performed where the usage of tractable formulation in DOPF algorithm development and its comparison to the benchmark solution are demonstrated.

Hanif, Sarmad↗

Distribution System Resilience Assessment Considering PV Vulnerabilities for Hurricane Events

Distribution networks are increasingly vulnerable to damage and outages from extreme weather events. The integration of solar photovoltaics (PVs) further complicates resilience analysis due to its weather-dependent nature. However, limited research has examined the impacts of weather on PVs under severe events like hurricanes. This paper proposes a probabilistic framework to assess distribution system resilience considering PV vulnerabilities during hurricanes. The framework incorporates (i) a spatiotemporal fragility model to evaluate failure probabilities for distribution lines and PVs, and (ii) resilience indices at both system and component levels. The approach offers valuable insights into the resilience of modern distribution grids under extreme weather conditions. Numerical results on the unbalanced IEEE 123-bus test system validate the effectiveness of the framework.

Vahedi, Soroush [University of Connecticut, Storrs↗

ML-Based Power System Stability Assessment Considering Network Topology Changes: WECC 20,000+ Bus System Case Study

Modern power grids are fast-changing and thus require real-time monitoring and online stability assessment. With the rapid development of machine learning (ML) techniques, using data-driven models to provide fast and accurate estimations of power system stability marginal information, such as frequency nadir for frequency stability and critical clearing time (CCT) for transient stability, have become possible. However, despite the numerous research on ML-based methods for frequency nadir and CCT prediction, there is limited work on the impact of different network topology changes. Furthermore, most previous studies only focused on small or synthetic systems, and there is a lack of research on actual large power system models. In this paper, the above issues are addressed by studying the actual U.S. Western Electricity Coordinating Council (WECC) system model with more than 20,000 buses. Massive simulations are conducted in PowerWorld Simulator to study the impact of various topology change scenarios on both frequency stability and transient stability. System operating information is extracted from the success dispatch cases of various network topologies to generate a comprehensive dataset for ML-based models. Two ML methods, random forest (RF) and multilayer perceptron (MLP) neural network, are trained and tested for both frequency nadir prediction and CCT prediction. Test results have proven the models are capable of online stability assessment for large power networks such as the WECC system with sufficient accuracy.

critical clearing time↗

Robustness Against Disturbances in Power Systems Under Frequency Constraints

The wide deployment of renewable generation and the gradual decrease in the overall system inertia make modern power grids more vulnerable to transient instabilities and unacceptable frequency fluctuations. Time-domain simulation based assessment of the system robustness against uncertain and stochastic disturbances is extremely time-consuming. In this paper, we develop an alternative approach, which has its roots in the input-output stability analysis for Lur'e systems. Our approach consists of a mathematically rigorous characterization of the external disturbances that the power system is transiently stable and the frequency constraints are not violated. As a result, the derived certificate is efficiently constructed via convex optimization and is shown to be non-conservative for different IEEE test cases.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Enhancing ACPF Analysis: Integrating Newton-Raphson Method with Gradient Descent and Computational Graphs

This paper presents a new method for enhancing Alternating Current Power Flow (ACPF) analysis. The method integrates the Newton-Raphson (NR) method with Enhanced-Gradient Descent (GD) and computational graphs. The integration of renewable energy sources in power systems introduces variability and unpredictability, and this method addresses these challenges. It leverages the robustness of NR for accurate approximations and the flexibility of GD for handling variable conditions, all without requiring Jacobian matrix inversion. Furthermore, computational graphs provide a structured and visual framework that simplifies and systematizes the application of these methods. The goal of this fusion is to overcome the limitations of traditional ACPF methods and improve the resilience, adaptability, and efficiency of modern power grid analyses. We validate the effectiveness of our advanced algorithm through comprehensive testing on established IEEE benchmark systems. Furthermore, our findings demonstrate that our approach not only speeds up the convergence process but also ensures consistent performance across diverse system states, representing a significant advancement in power flow computation.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Frequency Support From Electric Vehicles for Advancing Renewable Energy Integration

The integration of renewable energy resources (RERs) in the modern power grid is increasing rapidly because of aggressive decarbonization goals, lower costs, and increased government investment. However, higher penetrations of inverter-based generation can lead to frequency stability issues because of reduced system inertia. This paper develops a framework for quantifying the contribution of electric vehicles (EVs) toward providing frequency support to the grid and thus increasing the penetration limit of renewable energy resources (RERs). EVs are considered to provide both inertial response and primary frequency response support to the grid. A stochastic approach incorporating the uncertainties associated with the behavior of EVs is developed to derive the discharge limit of EV aggregators. A multi-machine system frequency response (MM-SFR) model is developed, which incorporates the dynamic virtual inertia and droop coefficients of EV aggregators derived from the EV control modules. Frequency security constraints are developed from this MM-SFR model, which, along with the converter voltage security and low voltage ride-through constraints, are integrated within a nonlinear optimization framework to determine the RER integration limit. Here, the efficacy of the proposed approach is validated using the RTS-GMLC test system.

25 ENERGY STORAGE↗

Perturbation-Based Diagnosis of False Data Injection Attack Using Distributed Energy Resources

Modern smart grid relies on various sensor measurements for its operational control. In a successful false data injection attack, the attacker manipulates the measurements from the grid sensors such that undetected errors are introduced into the estimates of the system parameters leading to catastrophic situations. This paper proposes a novel perturbation based false data injection attack detection mechanism that utilizes inverter based distributed energy resources (DERs) to create low magnitude perturbation signal in the distribution system voltage that is inconsequential to the normal grid operation. Two voltage sensitivity analysis based algorithms are designed to identify the optimal set of DERs that can create the voltage perturbation signal of desired magnitude. An analytical method of voltage sensitivity analysis is used to compute the magnitude of voltage perturbation signal at each node in a computationally efficient manner. Then, a detection mechanism is developed that checks for the presence of the perturbation sequence in each sensor measurement. A sensor measurement is deemed authentic if the voltage perturbation signal is present in the data. In case of sensor malfunction or cyber-attack, the perturbation signal will not be present in the measurement data. Performance of the proposed attack detection mechanism is validated via simulation of the IEEE 69 bus test system.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Elucidating Sodium-Sulfur Battery Chemistry using Operando Transmission X-ray Microscopy and X-ray Absorption Spectroscopy

Room-temperature sodium-sulfur (Na-S) batteries offer a beneficial and cost-effective solution for powering modern electric grids and devices. However, Na-S batteries suffer from performance decay during battery cycling due to the sluggish kinetics and polysulfide shuttling. Revealing the conversion mechanism of the Na-S chemistry is critical to designing high-capacity and stable Na-S batteries. In this study, we employed operando X-ray microscopy and operando X-ray absorption spectroscopy to elucidate the sulfur conversion in a carbon host using an ether-based electrolyte. We reveal the structural and chemical evolution of the sulfur cathode during cycling, which results in volume expansion and the dissolution of active material, ultimately affecting the battery performance. Our work provides fundamental insight into the sulfur reaction scheme, addressing the lingering challenges before establishing inexpensive Na-S batteries for broad applications, including portable electronics and large-scale energy storage.

Jagadeesan, Sathya Narayanan [SLAC National Accele↗

ADEPT Final Report: Dynamic Control of Grid Assets Using Direct AC Converter Cells

Seedling funding was secured through the ARPA-E program to develop a robust, utility-scale Power Converter Augmented Transformer (PCAT). The project designed, fabricated, and tested two 13 kV, 1 MW PCATs operating at an effective switching frequency of up to 50 kHz and at an efficiency of greater than 99%. Two versions of the PCAT were fabricated – one using an imputed DC link (IDCL) topology and the other using a back-to-back (BTB) topology. The IDCL avoids the use of electrolytic capacitors for bulk energy storage, thus improving the lifetime and decreasing the size of the converter, while the BTB topology uses an industry-proven topology that is more commercially viable in the short term. To give the PCAT a lifetime and maintenance profile compatible with typical existing utility assets, a novel Passive Thermal Management System (PTMS) was designed and integrated into both PCATs. The PTMS uses a thermosiphon to remove heat from the power electronic devices without forced cooling and reject it to the ambient environment. In addition, a fail-normal feature was implemented to ensure that in the event of PCAT failure the functionality of the underlying transformer is retained. Attainment of project objectives was verified through testing at the Georgia Tech National Electrical Energy Testing Research and Applications Center (NEETRAC). The IDCL-based PCAT had an efficiency of more than 99.10% and the BTB-based PCAT had an efficiency of more than 99.75%. During testing, the PTMS exceeded project requirements by rejecting the 5 kW output of the converters to a 40 °C environment while keeping devices junction temperatures within their tolerances.

24 POWER TRANSMISSION AND DISTRIBUTION↗

The Advanced Microgrid: Integration and Interoperability

This white paper focuses on "advanced microgrids," but sections do, out of necessity, reference today's commercially available systems and installations in order to clearly distinguish the differences and advances. Advanced microgrids have been identified as being a necessary part of the modern electrical grid through a two DOE microgrid workshops, the National Institute of Standards and Technology, Smart Grid Interoperability Panel and other related sources. With their grid-interconnectivity advantages, advanced microgrids will improve system energy efficiency and reliability and provide enabling technologies for grid-independence to end-user sites. One popular definition that has been evolved and is used in multiple references is that a microgrid is a group of interconnected loads and distributed-energy resources within clearly defined electrical boundaries that acts as a single controllable entity with respect to the grid. A microgrid can connect and disconnect from the grid to enable it to operate in both grid-connected or island-mode. Further, an advanced microgrid can then be loosely defined as a dynamic microgrid.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE/OE Load as a Resource R&D Overview [Slides]

DOE R&D and OE’s PSA and ISER programs support OE’s mission to modernize electric grid, enhance energy infrastructure security and reliability, and facilitate recovery from energy supply disruptions.

24 POWER TRANSMISSION AND DISTRIBUTION↗

WGRID-49 GMLC Project Report: Understanding the Role of Short-Term Energy Storage and Large Motor Loads for Active Power Controls by Wind Power

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 and the University of Colorado—on active power controls (APC) by wind power during 2013–2016. The studies detailed in the first APC by wind power project have shown tremendous promise for the potential for wind power plants to provide APC. The goal of this project was to continue the previous work and develop and validate coordinated controls of APC by wind generation, short-term energy storage, and large industrial motor drives for providing various types of ancillary services to the grid and minimizing loading impacts on wind turbines (e.g., drivetrains), thereby reducing operation-and-maintenance (O&M) costs and subsequently reducing the cost of energy generated by wind power. This work used the $30 million, multiyear DOE investments and the unique characteristics of NREL’s existing National Wind Technology Center test site, including a combination of multimegawatt utility-scale wind turbine generators, a 1-MW/1-MWh battery energy storage system (BESS), industrial variable-frequency motor drives, a 1-MW solar photovoltaic (PV) array, and a 7-MVA controllable grid interface. This combination of technologies allows for the optimization, testing, and demonstration of various types of APC by wind power in coordination with other generation sources (including regenerative loads) and energy storage to allow for enhancing or, in some cases, substituting the APC services by wind power and reducing impacts on wind turbine component life and thus increasing the availability and reliability of the power supply from wind

17 WIND ENERGY↗

Energy Storage in Integrated Resource Plans

Energy Storage in Integrated Resource Plans (IRPs) documents a review of how IRPs treated energy storage, particularly batteries and pumped storage hydro storage. The review examined IRPs available in fall 2017 and winter/early spring 2018, examining whether IRPs included storage at all, how many of the services provided by storage were included, the costs assumed for storage, and other factors. This report summarizes the results of the review.

25 ENERGY STORAGE↗

Reference Interoperability Procurement Language

Achieving interoperability involves reaching agreement on common interfaces and promoting interoperability through performance specifications. Effective integration practices are a simple, effective, and direct way of addressing the challenge. By deciding on an integration approach with well-defined interfaces and selecting systems and devices that conform to that approach and choosing integrators that have experience implementing the chosen approach, many problems can be avoided. No integration effort is seamless but by specifying interoperability requirements during the procurement process typical problems from ad hoc approaches can be avoided or reduced. By continuing this approach to its conclusion at the end of the procurement process, these same interoperability requirements may lead themselves to specified performance criteria that can be used to measure interoperability during implementation. The contractual language may contain performance incentives and penalties tied to these requirements as appropriate.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Coastal Community Resiliency Enhancement Using Marine Hydrokinetic (MHK) Resources and Networked Microgrids

Enormous challenges are inherent in the operation of modern distribution grids. In particular, distribution feeders can be severely compromised under extreme conditions such as large-scale weather events (e.g., hurricanes, floods, and other types of natural disasters). To combat this problem, they turn to local energy support from distributed energy resources, such as solar and wind, marine hydrolinetic (MHK), and other types of energy. In this report, we investigate the actual characteristics of MHK resources to enhance coastal community resiliency. Two typical types of MHK resources (i.e., wave and tidal resources) illustrate the coastal resilience enhancement framework. By identifying their operational characteristics, such as target time-scales and potential power generation variations, we detail a holistic coastal community resiliency enhancement framework that integrates both optimization and control efforts. The optimization problem is formulated to significantly minimize the power outage time at the critical infrastructures in coastal communities by implementing multiple autonomous and dynamic microgrids around MHK resources. Therefore, during severe power outages caused by natural disasters (e.g., floods, hurricanes), the coastal community load profiles can be satisfied using local MHK resources in each microgrid with limited or no power support from upstream power grids.

16 TIDAL AND WAVE POWER↗