Voltage Sag Predictor

Voltage Sag Analysis and Forecasting Tool

Voltage sag disturbances, or momentary decreases in voltage, are considered to be the most prominent power quality problem. This is largely due to the large number of occurrences throughout a typical distribution network, the increasing sensitivity of customer equipment to voltage sags, and the high costs of lost productivity and downtime. Because of heightened customer awareness of voltage sags and increased competition in the electric power industry, utilities are aggressively working with customers to identify how voltage sags impact facility operations, as well as how to protect against them.

The Voltage Sag Predictor (VSP^TM) was developed by Electrotek Concepts^Ž to help utility power quality engineers evaluate expected sensitivity to voltage sag events at customer facilities. The VSP evaluates a number of factors, including

Equipment sensitivity levels
Pre-fault conditions at equipment locations
Location and characteristics of short circuit faults

In addition to being an analytical tool, the VSP also can enable utilities to educate customers about various aspects of their facility's power quality, including

Expected power quality performance of utility and customer power systems
Importance of equipment immunity to voltage sags
The challenge presented by preventing sag-causing faults on the utility power system
The justification - both technical and economical - for power conditioning measures

How It Works

The VSP combines existing utility short circuit models with line performance data to develop the voltage sag predictions. The VSP was designed for use with ASPEN OneLiner^Ž, which provides sliding fault analysis. You import data from Aspen OneLiner into the VSP, and then use the software to calculate distribution system faults and produce performance graphs and conduct analyses.

The VSP provides you with a number of important features, including:

The ability to calculate the effect of customer load connections and transformers on overall performance.
The ability to determine an "area of vulnerability" given those load connections.
A performance graph detailing the different types of voltage sags (number of phases or phase angle shift) that the customer will experience.
The ability to enter system performance data by system voltage rating, or by individual line performance.
The ability to calculate and consider the effect of faults on parallel distribution lines to the customer.

Where the VSP really proves beneficial is in calculation of annual voltage sag profiles for customer facilities. Voltage sags can be characterized using their fundamental characteristics. This characterization is essential in standardizing the testing of equipment for immunity to voltage sags. You characterize sags by examining the three-phase voltage vectors and determining number of phases and phase angle shift. The VSP features a characterization wizard that helps automate this process, speeding up calculation of the sag profiles.

These profiles are increasingly being used to educate customers on equipment sensitivity to voltage sags, to provide customers a reasonable expectation of power system performance, and enabling both utilities and customers to evaluate the benefits of various power conditioning technologies.

Support Options

Electrotek provides support for the VSP through PQSoft^TM Support Service, a comprehensive support offering for power system simulation and analytical tools. Features include upgrades, specialized models, and online resources. To learn more, send e-mail to pqsoft@electrotek.com or call 865-470-9222.

Availability

The Voltage Sag Predictor can be purchased directly from Electrotek. Pricing for multi-user installations and support options is quoted upon request. For more information, send e-mail to pqsoft@electrotek.com or call 865-470-9222.

"Electrotek Concepts" is a registered service mark of Electrotek Concepts, Inc.
"OneLiner" is a registered trademark of Advanced Systems for Power Engineering, Inc.

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