MATLAB SIMULINK WORKSHOP

Building Basic Power System Using SimPowerSystems

What is power system?

An electrical network.

It comprises of:Generators

Load

Transmission lines

Support devices, e.g. transformers and protection devices.

Assessing the network

It is imperative to continuously assess the power network for any inconsistencies.

Type of possible assessment done:Load dispatch generator scheduling

Contingency analysis

Stability Studies

Stability studies for network expansion and improvements.

Methods of assessment

The standard approach done by utilities all over the world is by using a form of static load flow or power flow iteration.

Reason:Simple

Fast

Accurate for the constraint given to the system

Methods of assessment

Disadvantages:Inaccurate for dynamic scenarios

Static Load Flow

Objective:To compute the P and Q flow in the branches of a system (these values may be an indicator of line loading due to load or generator constraints)

To compute the resultant bus voltage levels

To compute generation levels due to load or generator constraints.

Overview of Static Load Flow

Using a mathematical model for the system, compute the P and Q flow in each branch.

Well established methods:Newton Raphson Iteration

Gauss-Sidel Iteration

Fast DeCoupled Newton Raphson Iteration

Using SimPowerSystems

The new name for the power system block set available in Matlab Simulink

The power system block set contains basic components which can also be customizable to suite application requirements.

Calling Power System blockset

Type powerlib at the MATLab prompt

At the powerlib window, select file-new-model, to setup a new circuit.

Using the powerlib library window, a simple circuit construction can be made.

Example circuit

AC

300km transmission line

R = 0.011 /kmL = 0.8674 mH/kmC = 13.41nF/km

Q = 110MVars

R = 180.1 /kmL = 26.525 mH/kmC = 117.84 nF/km

R = 2.0

Vs = 424.4kV rms0 degrees50Hz

Completed Circuit

Running basic calculations

Click on the run button

Clicking onto the scope may show the waveforms going in and coming out of the transmission line.

For practical example, please load file name psbmachines.mdl located in the matlab folder.

Advantages of SimPowerSystems

Advantageous for fast system prototyping, hence suitable for quick exploratory research related to power system components

Disadvantage of SimPowerSystems

As the system size increases, building the power system may be complicated hence may require computing overhead to compute basic power system iterations.

Hence a ‘program’ based 3rd party package is recommended, e.g. MatPower

Thank You