THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

State-of-the-art review on power grid resilience to extreme weather events: Definitions, frameworks, quantitative assessment methodologies, and enhancement strategies

The frequency of extreme events (e.g., hurricanes, earthquakes, and floods) and man-made attacks (cyber and physical attacks) has increased dramatically in recent years. These events have severely impacted power systems ranging from long outage times to major equipment (e.g., substations, transmission lines, and power plants) destructions. This calls for developing control and operation methods and planning strategies to improve grid resilience against such events. The first step toward this goal is to develop resilience metrics and evaluation methods to compare planning and operation alternatives and to provide techno-economic justifications for resilience enhancement. Although several power system resilience definitions, metrics, and evaluation methods have been proposed in the literature, they have not been universally accepted or standardized. This paper provides a comprehensive and critical review of current practices of power system resilience metrics and evaluation methods and discusses future directions and recommendations to contribute to the development of universally accepted and standardized definitions, metrics, evaluation methods, and enhancement strategies. This paper thoroughly examines the consensus on the power system resilience concept provided by different organizations and scholars and existing and currently practiced resilience enhancement methods. Research gaps, associated challenges, and potential solutions to existing limitations are also provided.

/pdf/power-system-resilience-current-practices-challenges-and-3p0fxnyf6d.pdf

Power System Resilience: Current Practices, Challenges, and Future Directions

Rare and extreme climate events may result in wide power outages or blackouts. The concept of power system resilience has been introduced for focusing on high-impact and low-probability (HILP) events such as a hurricane, heavy snow, and floods. Power system resilience is the ability of a system to reduce the likelihood of blackout or wide power outages due to HILP events. Indeed, in a resilient power system, as the severity of HILP events increases, the rate (but not the amount) of unserved loads diminishes. Suitable measures for managing power system resilience can be classified into three categories in terms of time, known as “resilience-based planning,” “resilience-based response,” and “resilience-based restoration.” The most widely used approaches, methods, and techniques in each of these categories, as well as the future trends for improving the power system resilience are reviewed in this article. The challenges of resilience in power systems with high penetration of renewable energy sources are also discussed in each of these categories.

A Review of the Measures to Enhance Power Systems Resilience

Energy infrastructures are perceived continuously vulnerable to a range of high-impact low-probability (HILP) incidents—e.g., earthquakes, tsunamis, floods, windstorms, etc.—the resilience to which is highly on demand. Specifically suited to battery energy storage system (BESS) solutions, this paper presents a new resilience-driven framework for hardening power distribution systems against earthquakes. The concept of fragility curve is applied to characterize an earthquake hazard, assess its impact on power distribution systems, and estimate the unavailability of the network elements when exposed to extreme earthquakes. A new metric is defined to quantify the network resilience taking into account the uncertain nature of such HILP events. A linear programming optimization problem is formulated to determine the capacity and location of the BESSs for enhanced resilience against earthquakes. Efficacy of the proposed framework is numerically analyzed and verified through application to a real-world distribution power grid.

Energy Storage Planning for Enhanced Resilience of Power Distribution Networks Against Earthquakes

Global environmental variations in the past two decades have contributed to a significant deviation of classic ecological patterns, leading to severe electricity outages triggered by extreme weather-driven phenomena. This has highlighted an urgent need for enhancing the resilience and robustness of the interconnected electricity grid against such high impact low probability (HILP) incidents. From the electrical safety point of view, it is essential to increase the operators’ awareness on a better understanding of such hazards and grid vulnerabilities, and enhance their preparedness on how to respond or mitigate the probable outages. This paper proposes a temporary, yet agile, restoration strategy in response to the forecasted HILP events, founded based on efficient utilization of the grid existing infrastructure, and aimed at improving its resilience against such extreme emergencies. The applied concept of reconfiguration is proactively planned to recover the electricity outages in a timely manner. In the meantime, two sets of metrics are proposed to quantify both the grid operational and infrastructure resilience. The presented framework aids the system operator to evaluate the outage recovery plans considering their impacts on system resilience and decide on the final implementation. The proposed approach is applied to the IEEE 118-bus test system facing an HILP event, where results reveal its applicability and efficiency.

Maintaining Electric System Safety Through An Enhanced Network Resilience

Electricity grid complexity with its diverse critical infrastructures has been continuously evolved into a more complicated network that is vulnerable to unpredictable hazards of internal and external origins. Resiliency assessment of the large-scale smart electricity grids has recently attracted many attentions in electric industry for more efficient daily operations in face of emergencies. This paper aims to quantify the power system resiliency in dealing with grid severe vulnerabilities and extreme emergencies. The suggested approach for resiliency improvement is to harness the existing system infrastructure, with minimum additional cost, through transmission network reconfiguration. The applied concept of reconfiguration is predictively planned and used as a temporary operation mechanism for the main sake of electricity outage recovery. The system resiliency features, e.g., flexibility, capacity recovery and the imposed cost indices, are quantified for each optimal reconfiguration option, helping the system operators evaluate the recovery options and decide on the final plan for implementation considering its impacts on system resiliency requirements. The suggested approach is tested on the IEEE 118-Bus test system under a critical contingency and the results reveal its applicability and efficiency.

Quantifying power system resiliency improvement using network reconfiguration

In this paper, an improved fixed-point hardware design of QR decomposition, specifically optimized for Xilinx FPGAs is introduced. A Givens Rotation algorithm is implemented by using a folded systolic array and the CORDIC algorithm, making this very suitable for high-speed FPGAs or ASIC designs. We improve the internal cell structure so that the system can run at 246MHz with nearly 24M updates per second throughout on a Virtex5 FPGA. The matrix size can be easily scaled up.

FPGA implementation of fast QR decomposition based on givens rotation

Sever weather condition together with other natural catastrophes can danger lives, disable communities, and disrupt electric utilities' generation, transmission and distribution systems. An incident at a high-voltage transmission line may results in more significant cascading failure if appropriate safety measured contingency schemes are not well developed or not achievable by system operators, in the case of these unpredictable events the loss of multiple substations and lines would result in the loss of electricity to millions of customers. Many strategic utilities which their functionality heavily depend on the continual existence of electricity might fall in the major hassle. Since, restoration or repair of the failed components may take days to weeks, depending on the ability to bypass damaged substations or disrupted lines using the built-in resilience of the interconnected grid, having a proper resilience-based strategy in face of extreme weather is of great importance.

Enhancing electric safety by improving system resiliency in face of extreme emergencies

The performance of photovoltaic panels depends on many factors. One factor involves the light reception angles at the panels in which the intensity of the received solar radiation from the sun at the earth is affected significantly by the diurnal and seasonal movement of the earth. The maximum output of the panels is achieved when the panels are perpendicular to the sun’s rays. This research is an empirical financial assessment of the benefit of using a dual-axis sun tracker versus a fixed-flat position, as well as a comparison of the performance of the two panels under such settings. The experiment was conducted using 190 W panels, a manual dual-axis sun tracker, and a data acquisition system, which collected and stored the experimental data. A significant improvement in output was noticed in the tracked panel. The overall average improvement for the entire data collection time interval was 82 %. The financial assessment was performed based on the energy market rate in Texas and the average price and operative expenses of the dual-axis sun trackers. The breakeven point for the dual-axis sun tracking system was found to be “never,” 13, and 6 years for 1-, 4-, and 9-panel configurations, respectively, in each system.

Semih Aslan

Papers

Maintaining Electric System Safety Through An Enhanced Network Resilience

Quantifying power system resiliency improvement using network reconfiguration

FPGA implementation of fast QR decomposition based on givens rotation

Enhancing electric safety by improving system resiliency in face of extreme emergencies

Fixed versus sun tracking solar panels: an economic analysis