| SimPowerSystems | |
Session 6: Introducing the Phasor Simulation Method
Up to now you have used two methods to simulate electrical circuits:
This section explains how to use a third simulation method: the phasor solution method. This technique is newly introduced in Version 2.3.
When to Use the Phasor Solution
The phasor solution method is mainly used to study electromechanical oscillations of power systems consisting of large generators and motors. An example of application of this method is presented in the next session to simulate a multimachine system. However, this technique is not restricted to the study of transient stability of machines. It can be applied to any linear system.
If, in a linear circuit, you are interested only in the changes in magnitude and phase of all voltages and currents when switches are closed or opened, you do not need to solve all differential equations (state-space model) resulting from the interaction of R, L, and C elements. You can instead solve a much simpler set of algebraic equations relating the voltage and current phasors. This is what the phasor solution method does. As its name implies, this method computes voltages and currents as phasors. Phasors are complex numbers representing sinusoidal voltages and currents at a particular frequency. They can be expressed either in Cartesian coordinates (real and imaginary) or in polar coordinates (amplitude and phase). As the electrical states are ignored, the phasor solution method does not require a particular solver to solve the electrical part of your system. The simulation is therefore much faster to execute. You must keep in mind however that this faster solution technique gives the solution only at one particular frequency.
| | Discretizing the PWM Motor Drive | Phasor Simulation of a Circuit Transient | |