Is there a way to model a synchronous machine as a voltage source, instead of current source?

My understanding as of right now is that the synchronous machine models in the Simscape library are modeled as constant current sources. I want the machine to act as a constant voltage source so I can connect it in series with another current source. Is there a way to do this that anyone has found? Thanks in advance!

Answer 1

[Riya]

Hello Lawrence,

As per my understanding, you want to know whether there is a way to model a synchronous machine as a voltage source, instead of current source.

Please note that in Simscape Electrical, synchronous machine models are typically implemented as voltage behind reactance models, which means they can be represented as voltage sources with some internal impedance. However, if you want to explicitly model a synchronous machine as an ideal voltage source, you can do so by creating a custom component that uses the Simscape language or by using built-in Simscape blocks to represent the machine's behavior.

Here's a simple example of how you can model a synchronous machine as a voltage source using Simscape blocks:

% Define the parameters for the synchronous machine as a voltage source 
V_nominal = 480; % Nominal voltage in volts 
f_nominal = 60;  % Nominal frequency in hertz 
omega_nominal = 2 * pi * f_nominal; % Nominal angular frequency in rad/s 
Ls = 0.01;       % Synchronous inductance in henrys 
Rs = 0.001;      % Synchronous resistance in ohms 
 
% Open a new Simscape model 
new_system('SynchronousMachineVoltageSource'); 
open_system('SynchronousMachineVoltageSource'); 
 
% Add a Controlled Voltage Source block 
add_block('powerlib/Elements/Controlled Voltage Source',... 
    'SynchronousMachineVoltageSource/VoltageSource',... 
    'Position', [200 100 230 130]); 
 
% Set the voltage source parameters 
set_param('SynchronousMachineVoltageSource/VoltageSource',... 
    'amplitude', 'V_nominal * sqrt(2)',... 
    'frequency', 'f_nominal',... 
    'phase', '0'); 
 
% Add a Series RLC Branch block to represent the internal impedance 
add_block('powerlib/Elements/Series RLC Branch',... 
    'SynchronousMachineVoltageSource/InternalImpedance',... 
    'Position', [300 95 380 135]); 

% Set the RLC parameters 
set_param('SynchronousMachineVoltageSource/InternalImpedance',... 
    'Resistance', 'Rs',... 
    'Inductance', 'Ls',... 
    'Capacitance', '0'); 

% Connect the voltage source to the internal impedance 
add_line('SynchronousMachineVoltageSource',... 
    'VoltageSource/1', 'InternalImpedance/1'); 

% Add a Voltage Measurement block to measure the terminal voltage 
add_block('powerlib/Measurements/Voltage Measurement',... 
    'SynchronousMachineVoltageSource/VoltageMeasurement',... 
    'Position', [450 90 480 140]); 

% Connect the internal impedance to the voltage measurement block 
add_line('SynchronousMachineVoltageSource',... 
    'InternalImpedance/1', 'VoltageMeasurement/1'); 

% Add a Terminator block for the voltage measurement's negative terminal 
add_block('simulink/Commonly Used Blocks/Terminator',... 
    'SynchronousMachineVoltageSource/Terminator',... 
    'Position', [500 130 510 140]); 

% Connect the negative terminal of the voltage measurement to the terminator 
add_line('SynchronousMachineVoltageSource',... 
    'VoltageMeasurement/2', 'Terminator/1'); 

% Add a Ground block 
add_block('simulink/Commonly Used Blocks/Ground',... 
    'SynchronousMachineVoltageSource/Ground',... 
    'Position', [330 180 340 190]); 

% Connect the ground to the internal impedance 
add_line('SynchronousMachineVoltageSource',... 
    'Ground/1', 'InternalImpedance/2'); 

% Save the system 
save_system('SynchronousMachineVoltageSource'); 

% Optionally, you can open the block diagram to see the layout 
open_system('SynchronousMachineVoltageSource'); 

This code sets up a simple Simscape model that represents a synchronous machine as a controlled voltage source with an internal series RLC branch to simulate the machine's internal impedance. You can adjust the parameters `V_nominal`, `f_nominal`, `Ls`, and `Rs` to match the characteristics of your synchronous machine.

Please note that this is a simplified representation and may not capture all the dynamics of a real synchronous machine, such as the effects of saturation, transient saliency, or damping windings. For more detailed modeling, you would need to incorporate additional elements and possibly use the Simscape language for custom component definitions.

For more information you can refer following articles for more information:

https://www.researchgate.net/post/How-can-I-synchronize-multiple-voltage-sources-on-single-transmission-line

I hope it helps!