Jim Burke

Calculating line losses in smart grid: A new rule of thumb

The nature of distribution system losses, techniques on how to measure them, and program requirements to minimize their cost constitute a major concern for todays competitive environment. On the other hand, development of smart grid technologies brings in massive data to power engineers and researchers. One of the challenges is how to utilize these data to help us better understand the electric grid. Although there are several limitations, the “1/3 rule” for losses, as one of the classic rule of thumbs, has been widely used by many utilities in practice. This paper proposes a new rule of thumb for losses calculation, which utilizes the data measured from smart grid to overcome the limitations of the “1/3 rule”. The use of this new rule and its advantages over the “1/3 rule” are demonstrated through a numerical example.

Distribution system neutral grounding

Distribution neutral grounding is probably one of the most confusing subjects faced by the utility distribution engineer. In an industry where utilities are combining practices, complicated by the fact that European utilities are purchasing US systems and vice versa, the confusion has been compounded. Questions being asked are: is good grounding really necessary; does poor grounding have advantages; what is the best grounding; when is grounding important; and when is it not? The purpose of this paper is to attempt to answer some of these questions. It is shown that while good grounding is usually preferred, there are times when good grounds are not important and may even be detrimental.

Stray voltage: two different perspectives

Stray voltage has become a major concern to humans as well as dairy cows. The problem is that dairy farms have considerably different requirements than the general costumer population. The paper presents a study on the effect of stray voltage on humans and dairy cows that may eventually lead for both the electric utility company and the dairy farmer to reach agreement over this problem.

Improving the reliability of power distribution systems through single-phase tripping

this paper discusses the reliability benefits (reduction in SAIFI and SAIDI) that could be achieved through the implementation of single-phase tripping in four-wire multigrounded medium-voltage distribution feeders. Several issues and concerns regarding the potential problems caused by single-phase tripping are discussed, and the potential reliability benefits due to the implementation of this protection scheme for a real distribution system of the USA are presented and discussed. These benefits were estimated by running multiple simulations using a predictive reliability model.

The impact of a “fuse blow” scheme on overhead distribution system reliability and power quality

this paper addresses the impact of a fuse blow philosophy on long lines commonly found in rural electric utilities as well as shorter lines which are ubiquitous in more urban areas. It also assesses the differences in the impact of these schemes in terms of both power quality (momentaries) and reliability issues. Detailed analysis of the impact on the utility system is presented and discussed.

The confusion over stray voltage

The subject of stray voltage, once mentioned only in relation to dairy farms, has today become an issue in the industry for other reasons, not the least of which is safety. The general reduction of industry participation in the standards-writing function of the IEEE has created a situation in which nonprofessionals, such as state legislators and lawyers, are rewriting definitions and creating new terms, arbitrary limits, and testing procedures, thereby costing the industry many millions of dollars, which could have been used far more wisely to promote both safety and reliability.

A Fuse-Blow Scheme

A fuse-blow philosophy has been adopted by some utilities in an effort to decrease the number of momentary average interruption frequency index (MAIFI) seen by their customers. This practice has the inherent drawback that, by converting a temporary fault (e.g., lightning and animals) into a sustained interruption, they are in effect decreasing the reliability of their system [i.e., system average interruption duration index (SAIDI) will increase]. This article addresses the impact of a fuse-blow philosophy on long lines commonly found in rural electric utilities as well as shorter lines that are ubiquitous in more urban areas. It also assesses the differences in the impact of these schemes in terms of both power quality (momentaries) and reliability issues. Detailed analysis of the impact on the utility system is presented and discussed.

Stray voltage: Two different perspectives

Stray voltage has become a major concern, in recent years, to humans as well as dairy cows. The problem is that dairy farms have considerably different requirements than the general customer population. Meeting the farm criteria may become much too expensive (and unnecessary) for all classes of customer service. At this point in time, the utility industry is trying to install one standard for all their customer classes. The purpose this paper is to present the dairy farmer and the utility sides of the topic. This is done via authorship by a utility consultant and a dairy farmer. Ultimately, the purpose of the paper is to allow for both the utility and the dairy farmer to reach agreement over this long standing problem.

Evaluation of induced stray voltages from transmission lines using EMTP

The purpose of this paper is to study the effect of transmission system parameters and operating conditions on generated stray voltage levels‥ This includes the transmission line conductor configurations, line loading levels, grounding system parameters, the feeder configuration (radial or ring configuration) and unbalance loading. This enables a better way to understand how different electrical parameters impact the level of NEV and currents at points of interest during different utility operating conditions. Excessive stray voltages levels may have a negative effect on dairy farm cows and endanger personnel safety. EMTP was used to simulate the coupled electromagnetic-power circuit system. EMTP models of the poles and the line phase, neutral, and ground wire were built to represent the transmission line electromagnetic behavior and the stray voltage generation mechanism. The parameters of the proposed models were obtained from the technical literature. Different simulations were conducted by varying the system parameters and operating conditions. A discussion of these results is presented.