Paper Presentations

The Physical Aspects of Harmonic Data Collection
Rod Hageman, PRIT Service, Inc.

Frequently installation specifications for variable speed drives will require monitoring of voltage and current harmonics to insure that the drive package (including transformers, reactors, or other harmonic mitigating devices) do not cause harmonics at some specified point in the power system to exceed a limit related to IEEE Std. 519 recommendations.

This presentation will look at the actual hardware necessary to collect the data required to perform the analysis. Limitations of instrument transformers and safety considerations for connection to the power system will be discussed.

Flywheel Paralleling for Power and Reliability Without Limitation
Gene Weaver, Pentadyne Power Corp.

To parallel or not to parallel with flywheels; that may be the question. Is it better to utilize the single largest flywheel possible to protect the load? Or, multiple flywheels strategically placed to minimize the effect of one system failure taking the entire load with it? Actual operating performance dictates answer as the need for larger load systems continue to grow. Paralleling for load or redundancy remains the issue with the customer as decision maker.

With flywheels replacing batteries customers are better able to utilize their space for most effective placement. Flywheel simplicity of operation and minimal maintenance requirements enhances customer reliability concerns. Ease of paralleling and no synchronization gear required results in satisfying total power requirements including adding for redundancy.

The technically advanced Pentadyne flywheel easily transfers its original stringent vehicular requirements directly to industrial applications. Maximization of loads in the MW range is accommodated along with demonstrated actual operating performance. This paper discusses performance paralleling for load and redundancy for the Pentadyne flywheel in specific markets.

A Novel Device and Method to Protect Sensitive Load from Voltage Sags
Ljubomir Kojovic, Cooper Power Systems

The prevention of voltage sags and interruptions in power systems are extremely important such that customers receive a stable power supply. However, there is a high probability that there will exist at some time a fault on one of several lines of a power system, wherein the fault can adversely cause voltage reduction (voltage sag) on the other lines connected to the same bus.

This paper describes an innovative and patented device and method to reduce voltage sags in power systems by using the Voltage Support Transformer (VST). The VST is a specially designed transformer for interconnection and mutual coupling of the same phases of two lines, connected in series with the loads. It uses a change in current from one line in which a fault condition exists to create a voltage change in one or more of the other lines of the network connected to the same bus, to maintain or support the voltage in those lines at or near pre-perturbation levels. The VST performance was verified by computer simulations and testing of a full-size VST in a high power laboratory.