How could I develop code to repeat evaluating these equations correctly?

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kam Pal 2021-2-15

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评论： kam Pal 2021-2-15

I need to code the equations below in my MATLAB code. The decision variable is P_bat and I need to repeat the calculations for loop = 1: T and for counter = 1:100

Battery pack

Discharging mode: C_bat(t+1) = max{ (C_bat(t) - P_bat(t)*delta_t/eta_d_bat), C_bat_min} for t=1,2...T (Equation 1)

Charging mode: C_bat(t+1) = min{ (C_bat(t) + P_bat(t)*delta_t*eta_c_bat), C_bat_max} for t=1,2...T (Equation 2)

Battery constraints

P_bat_min(t) <= P_bat(t) <= P_bat_max(t) (Equation 3)

where, P_bat_max(t) = min{P_bat_max, (C_bat(t) - C_bat_min)*eta_d_bat/delta_t} for t=1,2...T (Equation 4)

P_bat_min(t) = max{P_bat_min, (C_bat(t) - C_bat_max)*1/eta_c_bat*delta_t} for t=1,2...T (Equation 5)

SOC_bat(t) = C_bat(t)/C_bat_max (Equation 6)

SOC_bat_min<=SOC_bat(t)<=SOC_bat_max (Equation 7)

Here, P (power), C(capacity), eta(discharge/charge efficiencies), delta_t is the time step and all minimum and maximum quanities are defined earlier.

I started it as follows and I am not sure if I do it correct. If I use (T-loop) for delta_t in Equations 4 and 5, the answer is undefined when T=loop. I hope there should be a correct way in representing these in the code.

So, could someone please assist me to develop the code to represnt above equations? Should you need any more details, please let me know.

for loop: 1:T % where T=total time in hours

for counter: 1:100

C_bat(counter)= C_bat_max; % Battery maximum size

% Battery discharging

C_bat(counter+1)=C_ bat(counter)-((T-loop)*P_ bat(counter))/eta_d_bat;

% Battery charging

C_bat(counter+1) = C_ bat(counter)+((T-loop)*P_ bat(counter)*eta_c_bat);

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John D'Errico 2021-2-15

编辑：John D'Errico 2021-2-15

在 MATLAB Online 中打开

I'd start by learning MATLAB syntax.

Not this:

for counter: 1:100

But this:

for counter = 1:100

However, it looks like your real problem was in understanding how to form the boundary conditions. And it seems like you are the one who knows what you want to do there.

kam Pal 2021-2-15

在 MATLAB Online 中打开

Thank you for highlighting the basic error that I've done.It's a typo. If I do it as I've done below, when T=loop in Equations 4 and 5, the answer is undefined.

for loop = 1:T %  where T=total time in hours
for counter = 1:100
C_bat(counter)   = C_bat_max; % Battery maximum size 
C_bat(counter+1) = C_bat(counter)-((T-loop)*P_bat(counter))/eta_d_bat;  % Battery discharging
C_bat(counter+1) = C_bat(counter)+((T-loop)*P_bat(counter)*eta_c_bat);  % Battery charging
P_bat_max(counter)=(C_bat(counter)-C_bat_min)*eta_d_bat)/(T-loop);      % Equation 4         
P_bat_min(counter)=(C_bat(counter)-C_bat_max)/(eta_c_bat*(T-loop));     % Equation 5          
if P_bat(counter)>P_bat_max(counter)            % Checking upper and lower bounds
    P_bat(counter)=P_bat_max(counter);
end
if P_bat(counter)<P_bat_min(counter)
    P_bat(counter)=P_bat_min(counter);
end 
end
end