Silicon Carbide Technology Overview

After several years of research and development, Silicon Carbide has emerged as a prominent successor to conventional silicon in the field of power electronics due to its exceptional advantages. Silicon carbide material improves the efficiency of semiconductor devices and also facilitates usage of devices with much smaller form factor. The chemical and electronic properties of Silicon carbide translate to features which are useful for semiconductors especially in high power applications. These features include inherent radiation-resistance, high-temperature operating capacity, high voltage and power handling capacity. The use of SiC specifically in the areas of industrial control, power and renewable energy (solar & wind sector) also enables smaller cooling solutions in the system design. SiC electronics also find applications in electric vehicles and hybrid electric vehicles, electric traction control, power supply units, photovoltaic applications, converters and inverters.

Optimal Placement of Phasor Measurement Units for Improving Power System State Estimation Accuracy: A Heuristic Approach

This paper describes a heuristic approach for optimal placement of phasor measurement units (PMUs) in power system for improving state estimation accuracy. PMUs are able to measure highly accurate bus voltage phasors as well as branch current phasors incident to the buses at which PMUs are installed. Due to cost consideration of PMU placement, power grid utilities are interested in the knowledge of how to add a limited number of PMUs to their existing network in order to improve state estimation performance. State estimation results are calculated by the weighted least square (WLS) state estimation method. In the problem of adding PMU measurements into the estimator, two methods are investigated. Method I is to mix PMU measurements with conventional measurements in the estimator, and method II is to add PMU measurements through a post-processing step. These two methods can achieve very similar state estimation results, but method II is a more time-efficient approach without modifying the existing state estimation software. The proposed PMU placement approach is tested using IEEE 14-bus system, and the obtained figure and table might help planning engineering determine the optimal placement of PMUs when they want to place a few PMUs in their systems.

Designing and Building a Battery-Powered Car

For many years now Electrical Engineering students at the US Naval Academy have been involved in renewal energy types of projects, including electric boats and cars, and have participated in various competitions across the US. Of particular interest to us is the electric car, since it involves various aspects of electrical engineering. As part of their senior capstone project, and under our guidance and supervision, four students designed, built, and tested the power generation and distribution system, the motor control system for an electric car. This was accomplished by converting an originally gas-powered car into a battery-powered car, whereby solar panels are used to recharge the batteries. Towards this end, a mix of off the shelf parts and components, and homebuilt circuits were used. The design considerations include selecting an appropriate control system, choosing suitable batteries, utilizing solar panels to recharge the batteries, designing the lighting system for the vehicle, and implementing several key safety features, including an emergency shut-off switch.

Characteristics of Short-term LOLP Considering High Penetration of Wind Generation

Loss of Load Probability (LOLP) is an important measure of generation adequacy. A good understanding of the new characteristics of LOLP exhibited after integration of variable renewable generation is essential to the power system reliability. This paper presents the results of a study on the impact of wind generation on short-term LOLP, which then becomes a fastchanging stochastic process, driven by the intermittent and variable wind. We firstly introduce a mathematical model for calculating short-term LOLP, and then a novel quantitative measure of its behavior when converging to its steady-state level is derived. In addition, the corresponding empirical formulas are offered which can be used in practice to estimate the convergence time of LOLP under different conditions. Finally, an application of the outcomes of the analytical work in estimation of the dynamic behavior of shortterm LOLP with an actual wind generation profile is presented to show the significance of the developed measures.