SimPowerSystems

Steady-State Analysis

In order to facilitate the steady-state analysis of your circuit, a graphical user interface (GUI) is provided in the powerlib library. Copy the Powergui block into your circuit1 window and double-click the block icon to open it.

This opens the Steady State window where the steady-state phasors measured by the two measurement blocks are displayed in polar form.

Each measurement output is identified by a string corresponding to the measurement block name. The magnitudes of the phasors U1 and U2 correspond to the peak value of the sinusoidal voltages.

From the Steady State window you can also choose to display the steady-state values of the source voltage or the steady-state values of states by checking either the Sources or the States check box.

The state variable names contain the name of the block where the inductor or capacitor is found, preceded by the Il_ prefix for inductor currents or the Uc_ prefix for capacitor voltages.

The sign conventions used for the voltages and currents of sources and state variables are determined by the orientation of the blocks:

• Inductor currents flowing in the arrow direction are considered positive.
• Capacitor voltages are V_{block output} - V_{block input}.

Note    Depending on the exact position of the various blocks in your circuit1 diagram, the state variables might not be ordered in the same way as in the preceding figure.

Now, from the Tools menu of the powergui, select Initial Values of State Variables --> Display or Modify Initial State Values. The initial values of the six state variables (three inductor currents and three capacitor voltages) are displayed. These initial values are set in order to start the simulation in steady state.

Session 2: Analyzing a Simple Circuit

Frequency Analysis