Adam B. Birchfield

Grid Structural Characteristics as Validation Criteria for Synthetic Networks

This paper presents a methodology and set of validation criteria for the systematic creation of synthetic power system test cases. The synthesized grids do not correspond to any real grid and are, thus, free from confidentiality requirements. The cases are built to match statistical characteristics found in actual power grids. First, substations are geographically placed on a selected territory, synthesized from public information about the underlying population and generation plants. A clustering technique is employed, which ensures the synthetic substations meet realistic proportions of load and generation, among other constraints. Next, a network of transmission lines is added. This paper describes several structural statistics to be used in characterizing real power system networks, including connectivity, Delaunay triangulation overlap, dc power flow analysis, and line intersection rate. The paper presents a methodology to generate synthetic line topologies with realistic parameters that satisfy these criteria. Then, the test cases can be augmented with additional complexities to build large, realistic cases. The methodology is illustrated in building a 2000 bus public test case that meets the criteria specified.

A methodology for the creation of geographically realistic synthetic power flow models

To enable greater innovation in power systems, our research seeks to create entirely fictitious synthetic power system networks that capture the functionality, topology, and defining characteristics of the actual U.S. transmission system, and thus provide realistic test cases for research, without revealing any sensitive information. Creation of these models relies only on publicly available data and statistics derived from the actual grid. This paper outlines two fundamental steps for the creation of synthetic power system models: geographic load and generator substation placement and assignment of transmission line electrical parameters.

Statistical Considerations in the Creation of Realistic Synthetic Power Grids for Geomagnetic Disturbance Studies

Studies to evaluate the power system impacts of geomagnetic disturbances (GMDs) can benefit from geographically realistic public test cases to validate methodologies and analysis tools. Presently very few GMD test cases exist that are not restricted by data confidentiality. In this paper, we outline a method to generate completely synthetic transmission system networks suitable for GMD studies. Public energy and census data form the basis for generation, load, and geographic substation placement. The transmission line topology of the synthetic network is designed to match statistical characteristics observed on the Eastern Interconnect in North America: average nodal degree, average shortest path length, and average clustering coefficient. We apply the Delaunay triangulation to transmission network synthesis, showing it provides an excellent starting place for generating realistic topologies. A 150-bus case is developed and released with benchmark GMD results, for using in testing GMD models and methods.

Application of Large-Scale Synthetic Power System Models for Energy Economic Studies

Due to information confidentiality issues, there is limited access to actual power system models that represent features of actual power grids for teaching, training, and research purposes. The authors’ previous work describes the process of creating synthetic transmission networks, with statistics similar to those of actual power grids. Thus, this paper outlines a systematic methodology to augment the synthetic network base case for energy economic studies. The key step is to determine generator cost models by fuel type and capacity. Based on statistics summarized from the actual grids, two approaches are proposed to assign coefficients to generator cost models. To illustrate the proposed creation procedure, we describe the construction of a synthetic model for Electric Reliability Council of Texas footprint. Simulation results are presented to verify that the created test system is able to represent the behavior of actual power systems.

A Comparison of Peak Electric Fields and GICs in the Pacific Northwest Using 1‐D and 3‐D Conductivity

Geomagnetically induced currents (GICs) are a result of the changing magnetic fields during a geomagnetic disturbance interacting with the deep conductivity structures of the Earth. When assessing GIC hazard, it is a common practice to use layer-cake or one-dimensional conductivity models to approximate deep Earth conductivity. In this paper, we calculate the electric field and estimate GICs induced in the long lines of a realistic system model of the Pacific Northwest, using the traditional 1-D models, as well as 3-D models represented by Earthscopes Electromagnetic transfer functions. The results show that the peak electric field during a given event has considerable variation across the analysis region in the Pacific Northwest, but the 1-D physiographic approximations may accurately represent the average response of an area, although corrections are needed. Rotations caused by real deep Earth conductivity structures greatly affect the direction of the induced electric field. This effect may be just as, or more, important than peak intensity when estimating GICs induced in long bulk power system lines.

Power Flow Convergence and Reactive Power Planning in the Creation of Large Synthetic Grids

To encourage and support innovation, synthetic electric grids are fictional, designed systems that mimic the complexity of actual electric grids but contain no confidential information. Synthetic grid design is driven by the requirement to match wide variety of metrics derived from statistics of actual grids. In order to scale these systems to 10,000 buses or more, robust reactive power planning is needed, accounting for power flow convergence issues. This paper addresses reactive power planning and power flow convergence in the context of large synthetic power grids. The iterative algorithm presented by this paper supplements a synthetic transmission network that has been validated by a dc power flow with a realistic set of voltage control devices to meet a specified voltage profile, even with the constraints of difficult power flow convergence for large systems. The algorithm is illustrated with an example new synthetic 10,000 bus system, geographically situated in the western United States, which is publicly available and useful for a variety of research studies. An analysis is shown validating the synthetic system with actual grid characteristics.

Convergence characteristics of the variable projection method for mode extraction

This paper reviews the variable projection method (VPM) for power system modal analysis and analyzes the methods convergence characteristics. The purpose of the VPM and other modal analysis tools is to decompose time series data into damped or undamped sinusoidal components, which provide insights into the dynamics of a measured or simulated disturbance. The paper gives five example cases of modal analysis with VPM, varying in size from a single synthetic signal to a 30-signal, 7-mode data set from simulations of a large actual power system. The analysis provides an initial indication that the VPM often finds a solution close to the matrix pencil initialization, and that the methods convergence speed can vary. While the inner loop of the method, the line search, is robust and quick, the outer VPM loop sometimes converges linearly or slower, requiring hundreds of iterations. Simpler cases with fewer modes tend to have a more consistent convergence, and are less sensitive to the initial modes selected.