Software applications in this program may have been updated in the subsequent program. Please check here to see complete list of enhancements:
DSTAR’s SEDS software was upgraded previously in Program 11 to perform optimization of transformer size and conductor size selections to minimize first costs while respecting voltage drop and flicker constraints. Since energy efficiency is of interest to member utilities, the contributions of losses to total owning costs should also be part of the optimization of the transformer selection and secondary system design. This SEDS enhancement calculates and evaluates the costs of losses when optimizing transformer and secondary cable selections. The transformer database is expanded to include load and no-load losses (resistance of cables is already present in the database). Using the loss and resistance values, along with current flows from the particular case being simulated, total no-load and full-load system (distribution transformer and secondary cables) losses are calculated. A and B factors set by the program administrator (for each company) are used to monetize the life-cycle costs of losses on a first-cost equivalent basis. Selection of the transformers and cables are optimized on a total-owning cost basis.Read More →
The previous expansions of the e-handbook under Programs 10 and 11 significantly expanded the scope of the e-Handbook to include a variety of data tables, guidelines, discussions and calculations and improved the look and feel of the application. This expansion includes the following items:
- DG impact and interconnection issues,
- Module on overhead conductor sag and tension,
- Conductor damage prevention information and charts,
- Distribution transformer loading based on ambient temperature and load,
- Wildlife control and protection primer,
- Enhance/modify short-circuit calculator, and
- Update existing material and legacy calculation sheets.
This project develops loss contribution factors for distribution equipment by building prototype distribution models and calculating power loss from the substation to the services at peak, and energy loss over the course of a typical annual load cycle. The models developed have varying customer load and design/construction characteristics. This investigation includes a general literature search on the issue. The findings are used to determine how much typical equipment contributes to distribution system losses, and to recommend and evaluate distribution design practices to reduce losses. The deliverable is a report that describes the findings, discusses how to minimize losses by equipment selection and sizing, and identifies the best ways to economically improve energy efficiency efficiency of the utility distribution system. The project is completed in two phases: a power loss investigation and a companion energy loss investigation. The phase 1 report (available online now) will be augmented with the phase 2 findings.Read More →
For the past century, the electric utility industry has been utilizing predominantly wood poles to support both transmission and distribution overhead circuits. In recent years, distribution utilities have been progressively using steel, concrete, and fiberglass as substitutes for wood poles. In many cases these "new" materials are being combined on circuits with existing older wood structures. Since non-wood materials used for distribution strictures have very different lightning withstand and mechanical strength properties, DSTAR members are concerned about the impact on system reliability.
This project is focused on investigating the impacts of non-wood pole stucture (i.e. concrete, steel and fiberglass reinforced poles) on overall system reliability. The project is divided into three main tasks: lightning performance assessment, mechanical strength considerations, and impact on overall system reliability.
This project is ongoing. Final results are expected shortly.Read More →
The main goal of this project is to investigate how a high penetration of “new” and existing load technologies would affect the nature of utility electric load, and as a result, what effect this would have on conventional planning and operation procedures. The investigation begins by looking at individual loads and devices and assessing their characteristics with regard to issues such as harmonic injection, voltage dependency, usage profile, pick-up/inrush current, power factor and other non-harmonic power quality concerns. With these loads aggregated to the feeder level in various ways, the impact on operation and planning functions is then be assessed. Some of these functions include: Conservation voltage reduction, Reactive power management, Energy efficiency, Peak shaving strategies, Power quality and reliability concerns, Load control and Demand-Side Management (DSM) programs. Existing load models are studied to determine how well they reflect the changing nature of loads. Aggregated loads are simulated at the feeder level to assess the impact of aggregated new loads on system planning and operations. A sensitivity study shows system tolerance to mixes and penetrations of load types. The final is a 168-page report that details the methodology and findings.Read More →
The application of current limiting fuses for distribution transformer and capacitor protection is not new to the utility industry. However, as DSTAR has recognized, over the years during which current limiting fuses have been applied, transformer and capacitor manufacturer equipment tank specifications have changed, ultimately affecting their energy withstand ratings to an internal fault. As a result, the application of current limiting fuses needs to be re-evaluated in order to determine appropriate guidelines in today’s environment. This issue is even more important as transmission system impedances are decreasing and substation transformer sizes are increasing. As a result, the maximum available fault current that a distribution system can deliver to internal distribution transformer faults is higher than they have ever been. Since energy is a function of current squared, utilities are contemplating the need for current liming fuses where they presently do not exist. The cost comparison of current limiting fuses is much greater than their expulsion fuse counterparts and correct application has a significant economic impact in addition to equipment protection. This DSTAR project is timely and provides useful guidance in this area for the electric distribution community.Read More →
The fundamental goal of this project is to determine the optimal combination of different types of controls and settings for different types of distribution feeders (such as urban, rural, or a combination of urban and rural) under various circumstances, given the existing capacitor bank locations and ratings. For the simulation exercise, the “optimal” control or combination of controls is defined as the one that minimizes total system losses over the year. Some of the “various circumstances” relevant to this study may include loading variations, load mix variations, and others to be determined. A secondary project goal is to understand and compare how capacitors are controlled after placement, including the design objectives, required measurements, best-fit scenarios, assumptions, advantages and tradeoffs. The results of this project can be used as a guideline by DSTAR members.
This project is ongoing. Final results are expected shortly.Read More →