I have a MATLab invalid expression when calling variables.

I have a MATLab code but keeps giving me ivalid expression when calling variable in the code. Below is the code.

% Sample MATLAB code for OPF analysis of a distribution network with OLTC and SVC

% Load the bus admittance matrix, generation, and load data

% You should replace these with your actual data

Y_bus = load('bus_admittance_matrix.mat');

generation = load('generation_data.mat');

load_data = load('load_data.mat');

% Initialize variables

num_buses = 15;

num_gen_buses = 3; % Number of buses with generation

num_oltc_buses = 2; % Number of buses with OLTC

svc_bus = 8; % Bus number with SVC

% Define parameters

V_max = 1.05; % Maximum voltage magnitude

V_min = 0.95; % Minimum voltage magnitude

S_max = 100; % Maximum apparent power limit

% Initialize optimization variables

P_gen = zeros(num_gen_buses, 1);

Q_gen = zeros(num_gen_buses, 1);

V_mag = ones(num_buses, 1); % Initialize voltage magnitudes to 1.0 p.u.

% Perform OPF

options = optimoptions('fmincon', 'Display', 'iter', 'Algorithm', 'interior-point');

[x, fval] = fmincon(@(x) objective_function(x, Y_bus), [P_gen; Q_gen; V_mag]; ...

[]; []; []; []; []; [];

@(x) constraints(x;Y_bus; num_gen_buses; num_oltc_buses; svc_bus; V_max;V_min; S_max), options);

% Extract results

optimal_P_gen = x(1:num_gen_buses);

optimal_Q_gen = x(num_gen_buses+1:2*num_gen_buses);

optimal_V_mag = x(2*num_gen_buses+1:end);

% Display results

disp('Optimal Generation:')

disp(optimal_P_gen);

disp('Optimal Voltage Magnitudes:')

disp(optimal_V_mag);

% Define the objective function to be minimized

function cost = objective_function(~, ~)

% Define your objective function here

% This could be a cost function related to generation, voltage deviations, etc.

% Example: cost = sum(x(1:num_gen_buses)); % Minimize total generation

end

% Define the constraints

function [c, ceq] = constraints(~, ~, ~, ~, ~, ~, ~, ~)

% Define your inequality and equality constraints here

% Example: c = x(1:num_gen_buses) - 50; % Generation should be at least 50 MW

% ceq = x(2*num_gen_buses+1:end) - 1.0; % Voltage magnitudes should be 1.0 p.u.

end

Answer 1

[Torsten]

@(x) constraints(x;Y_bus; num_gen_buses; num_oltc_buses; svc_bus; V_max;V_min; S_max)...

Function inputs are separated by ",", not by ";".

Answer 2

[MarKf]

What would be the error?

I can already see some errors in the OPF (I'm guessing the mistake would be using semicolons ";" instead of commas "," which is why the actual error thrown is missing a closed parethesis ")", you're also likely missing a next line "..."). Something like this maybe:

[x, fval] = fmincon(@(x) objective_function(x, Y_bus), [P_gen; Q_gen; V_mag], ...
    [], [], [], [], [], [], ...
    @(x) constraints(x,Y_bus, num_gen_buses, num_oltc_buses, svc_bus, V_max,V_min, S_max), options);

The cost and constrain functions are also not complete. So this is not the final code. If that's the case, we wouldn't be able to recreate the error, also without the data, but if this is what you are talking about, then I suggest you be more careful or brush on your basics.