POWER SWINGS

Functionality and distinctive features:

• The observation point of electrical quantities is moved along the high-voltage line with the help of the "All-Seeing Eye";
• The process phase (angle between the EMFs of the equivalent generators, speed of the process) is adjusted manually with the circle marker on the "Time machine";
• The absolute value of resistance of the line is assumed to be equal to one;
• The line impedance angle, the p.u.-value and angle of the systems impedances and the EMF-ratio of the equivalent generators are specified using the fields on the right;
• The display (visibility) of the current and voltage phasors can be changed using the check boxes on the right;
• The radio buttons allow you to set three options for the location of the electrical center (EC);
• The circuit elements are linear and therefore have no frequency dependent parameters;
• The slip is considered to be small, so the symbolic (complex) method of circuit calculation is applicable;
• A dot serves as decimal separator;
• The interactive model works on a PC with Opera, Chrome, Firefox and Safari browsers.

Description:

The interactive model shows the basic quantities and the relationships between them in a two-machine asynchronous operation. It can be two parts of a power system, a generator with full excitation operating asynchronously with a power system or a excited synchronous motor, which is due to some disturbing influences pulled out of synchronism (out-of-step).

The phasor diagrams of EMF, voltages, currents are plotted in a coordinate system rotating with frequency (ω₁+ω₂)/2. If by the slip frequency we understand ω_s=ω₂-ω₁, then the frequency phasor ω₁ will rotate with frequency -ω_s/2, and the frequency phasor ω₂ with frequency ω_s/2. It turns out that, relative to such a "middle" coordinate system, the EMFs of the equivalent generators always rotate with the same angular velocity in different directions. If the phasor doesn't rotate, it indicates that it represents a signal of frequency (ω₁+ω₂)/2.

The impedance diagram shows the impedances of the network elements whose parameters are defined in the fields on the right and the impedance that is calculated by the distance protection. The voltage for calculating this impedance is taken at the location of the "All-Seeing Eye" marker. The positive current direction is defined from left to right.

The voltage diagram shows the voltage distribution (without the angle) along the line.