


For applications requiring excitation current 15 Amps to 10,000 Amps ECS2100 — DECS-400 — Alterrex Convection-Cooled Bridges — DECS-200/200N Pan Chassis — PSS-100 — Synchronous Motor Control

PSS-100 Power System Stabilizer

The PSS-100 is a two-input, microprocessor-based stabilizer that measures change of speed and change of power to produce the integral of accelerating power. It provides supplementary damping for low frequency power system oscillations ranging from 0.1 to 5.0Hz, which covers local mode, inter-area mode and inter-unit mode power system oscillations.

The PSS-100 features:

Dual microprocessor based design
Three programmable control modes
Non-volatile flash memory
Multiple levels of Password protection
Isolated output signal with gain adjustments
Metering capabilities and internal diagnostics
Event Recording and Data Capturing
IRIG-B provisions
Up to four setting groups for optimizing system tuning
Testing and commissioning features
50Hz or 60Hz operation
1 Amp or 5 Amp models
Programmable logic timers for sequencing

Accepts 3 phase 4 wire (Wye) or 3 phase 3 wire (Delta) sensing voltages
Windows®-based BESTCOMS™ PC software provides testing aids

Download Bulletin SRC for more information or download the product manual

And, Application Notes:
EX-PSS1 - Solutions utilizing voltage regulator adjustment or a power system stabilizer
EX-PSS2 - The features of the PSS-100 Power System Stabilizer

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Why use a Power System Stabilizer?

Electrical power oscillations can occur on power systems that contain generation equipped with fast acting excitation systems. These oscillations occur when a large amount of power is transmitted over long transmission lines. In some cases, this limits the amount of power able to be transmitted.

There are three types:

Inter-unit Oscillations - These oscillations involve two or more synchronous machines at a power plant or nearby plants.
Local Mode Oscillations - These oscillations involve one or more synchronous machines at a power station swinging together against a comparatively large power system or load center.
Inter-area Oscillations - These oscillations involve combinations of many machines on one part of a power system swinging against machines on another part of the system.

To illustrate a local mode oscillation, a small hydro turbine generator was experiencing potentially damaging power oscillations when the unit load was increased to more than 0.5 pu, with oscillations triggered by small changes in load or terminal voltage.

When the dual-input type power system stabilizer was implemented, the turbine generator response improved substantially. In operation, the unit was able to deliver rated load, with no danger from power oscillations threatening to damage the machine.

To learn more about the use of power system stabilizers, download the technical papers on Power System Stability and Understanding Power System Stability.

For more information on negative field forcing voltage regulators and power system stabilizers, see the technical paper "Suitability of Excitation Systems for PSS Applications" from the Power Engineering Society General Meeting, 2003

PSS-100 Power System Stabilizer mounted in
DECS-400 Custom System

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Does the need for a PSS depend on location?

In the Western United States machines are required to have power system stabilizers to improve the dynamic stability of the system. With the limited transmission capability and high loading expectations of the system, the transmission lines are stressed, which makes them particularly vulnerable to high loading margins and the likelihood of a sustained or growing oscillation after a fault. The power demand on the transmission system continues to spiral as load demands peak daily and the requirements may spread across the US.

For more information on current and proposed NERC requirements, see the technical paper, NERC Policies Affecting the Power Industry.

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What about setup and testing of the PSS?

According to NERC/WECC requirements where PSS are utilized, their activity are to be reported and it is likely that performance testing of the generator excitation system will become mandatory.

The PSS-100 offers built in features to perform step tests and automatically log the data to ease the burden of performing required tests and provide permanent records for future analysis.

Various self-generated test signals are available to inject internally to the PSS-100 or externally into the excitation system. Test signals include Sine, Step, Sine Sweep, and Square Wave modes.
Dedicated input for external test signal generators.
Software controlled switches allow test signal insertion at different points in stabilizer algorithm.
Data logging of PSS-100 internal variables for test results review.
Programmable logic and serial commands to control tests and data logs.
Dynamic System Analyzer and Sequence of Events

Today, as test tools are part of the excitation system setup software, you can eliminate hours or even days of setup. One laptop and serial cable can be used for onsite testing.

For more information feature enhancements, see the technical paper, Feature Enhancements in New Digital Excitation System Speeds Performance Testing

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Options to consider when adding or replacing a PSS

To learn more about the options Basler provides when adding a Power System Stabilizer and replacing an existing Power System Stabilizer, visit our Basler Solutions page.

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For applications requiring excitation current 15 Amps to 10,000 Amps

PSS-100 Power System Stabilizer

Why use a Power System Stabilizer?

Does the need for a PSS depend on location?

What about setup and testing of the PSS?

Options to consider when adding or replacing a PSS