Satish Rajagopalan

Hybrid distribution transformer: Concept development and field demonstration

Todays distribution system is expected to supply power to loads for which it was not designed. Moreover, high penetration of distributed generation units is redefining the requirements for the design, control and operation of the electric distribution system. A Hybrid Distribution Transformer is a potential cost-effective alternative solution to various distribution grid control devices. The Hybrid Distribution Transformer is realized by augmenting a regular transformer with a fractionally rated power electronic converter, which provides the transformer with additional control capabilities. The Hybrid Distribution Transformer concept can provide dynamic ac voltage regulation, reactive power compensation and, in future designs, form an interface with energy storage devices. Other potential functionalities that can be realized from the Hybrid Distribution Transformer include voltage phase angle control, harmonic compensation and voltage sag compensation. This paper presents the concept of a Hybrid Distribution Transformer and the status of our efforts towards a 500 kVA, 12.47 kV/480 V field demonstrator.

Power quality disturbances within DC data centers

As data center energy consumption continues to increase, various options are being considered that could improve the efficiency of existing and future data centers. One way is to operate the facility on a DC distribution system. This can eliminate intermediate DC/AC and AC/DC power stages, thereby improving the efficiency of the entire data center power delivery system. While the benefits of a DC data center have been clearly proven through demonstrations and analysis, it is of paramount importance to analyze issues that will impact its practical implementation. Power quality is one such issue whose importance cannot be dismissed due to its direct connection to datacenter reliability and uptime. This paper discusses the various power quality disturbances that can occur in DC data centers, their impact on system performance, and design considerations that must be taken into account for mitigating such disturbances.

A practical approach for belt slip detection in automotive electric power generation and storage system

This paper addresses a specific fault detection and isolation (FDI) issue within the automotive electric power generation and storage (EPGS) system, i.e., the detection of belt slip. A practical model-based algorithm is proposed to detect the belt slip and estimate the belt-slip size using sensors that are currently available in most of the production vehicles, which limits the cost and is especially desirable for the cost-sensitive automotive industry. This paper presents the derivation of the proposed algorithm, the calibration procedure, together with some simulation experiment results.1 2

Fast charging: An in-depth look at market penetration, charging characteristics, and advanced technologies

Plug-in Electric Vehicles (PEVs) are now available in many North American and European markets, with more models expected to become available to consumers in the coming years. These vehicles will present utilities with opportunities as well as challenges as their numbers potentially grow to hundreds of thousands of vehicles connected to the electric grid for charging. In order to support PEV adoption in the market place, it is expected that consumers will demand faster charge rates especially for the all electric vehicles. Faster charge rates require higher power electrical charging systems and the infrastructure to support these fast charging systems. With a view to comprehensively understand the impact of DC fast charging on the customer as well as the electric utility, Electric Power Research Institute (EPRI) has been conducting detailed research into the market potential, technical capabilities, and installation costs. Demand charges and installation costs are currently the most significant barriers widespread adoption of fast charging. Creating a sustainable business case for fast charging will require economics that match utilization. This paper will discuss these findings in depth and will also provide an update on the status of DC fast charging related standards. With a view to address these shortcomings, EPRI has developed a direct medium-voltage fed all solid-state fast charging system, the Utility Direct Medium Voltage Fast Charger (UDFC). Such a system would allow the charging system to be connected directly to the medium voltage system, offer multiple ports so that total charging capacity can be intelligently shared between multiple vehicles at once, simplify installation and increase overall system efficiency. This paper will also present an overview of this concept and its benefits.

National grid microgrid feasibility evaluation: Case study of a rural distribution feeder

Many electricity customers in rural areas served by single radial transmission or sub-transmission line have been experiencing long duration of power outages. The need for reliable power supply, grid resiliency and rapid restoration is pushing utilities to take a renewed look at the operation of these rural feeders. One possible solution is to operate rural communities as a microgrid when the power supply line is out of service due to a permanent fault or for any other reason. The work presented in this paper examines technical and economic feasibility of operation of the two such remote communities in the rural areas of New York in a microgrid mode. The focus of this paper is to present high-level results of the case study and also to provide recommendations for utilities to evaluate the feasibility of microgrid operation as a potential solution to improve their power supply reliability and grid resiliency.