Series RLC Branch (SimPowerSystems)

Implement a series RLC branch

Library

Elements

Description

The Series RLC Branch block implements a single resistor, inductor, or capacitor, or a series combination of these. To eliminate either the resistance, inductance, or capacitance of the branch, the R, L, and C values must be set respectively to 0, 0, and infinity (inf). Only existing elements are displayed in the block icon.

Negative values are allowed for resistance, inductance, and capacitance.

Dialog Box and Parameters

Resistance R

The branch resistance, in ohms (

Inductance L

The branch inductance, in henries (H).

Capacitance C

The branch capacitance, in farads (F).

Measurements

Select Branch voltage to measure the voltage across the Series RLC Branch block terminals.

Select Branch current to measure the current flowing through the Series RLC Branch block.

Select Branch voltage and current to measure the voltage and the current of the Parallel RLC Branch block.

Place a Multimeter block in your model to display the selected measurements during the simulation. In the Available Measurements list box of the Multimeter block, the measurement is identified by a label followed by the block name.


Measurement	Label
Branch voltage	`Ub:`
Branch current	`Ib:`

Example

Obtain the frequency response of a fifth-harmonic filter (tuned frequency = 300 Hz) connected on a 60 Hz power system. This example is available in the psbseriesbranch.mdl file.

The network impedance in Laplace domain is

To obtain the frequency response of the impedance you have to get the state-space model (A B C D matrices) of the system.

This system is a one-input (Vsource) and one-output (Current Measurement block) system. If you own the Control System Toolbox, you can get the transfer function Z(s) from the state-space matrices and the bode function as follows:

[A,B,C,D] = power2sys('psbseriesbranch');
freq = logspace(1,4,500); 
w = 2*freq;
[Ymag,Yphase
] = bode(A,B,C,D,1,w);
% invert Y(s) to get Z(s)
Zmag = 1./Ymag;
Zphase = -Yphase;
subplot(2,1,1) 
loglog(freq,Zphase)
grid
title('5th harmonic filter')
xlabel('Frequency, Hz')
ylabel('Impedance Zmag') 
subplot(2,1,2) 
semilogx(freq,Zphase) 
xlabel('Frequency, Hz') 
ylabel('phase Z') 
grid

You can also use the Impedance Measurement block and the Powergui block to plot the impedance as a function of frequency. In order to measure the impedance you must disconnect the voltage source.

Saturable Transformer Series RLC Load