Simulink pump transfer function output remains zero

Hello,

I am working on a pump station model in MATLAB/Simulink with a 110 kW induction motor and centrifugal pump.

I derived the transfer function of the pump, but my system output stays at zero during simulation.

Transfer function:

Gp(s) = ...

Why does the output remain zero?

Is my model structure correct?

Thank you.

[Nabiyev Muslim]

The simulink model is ready and the simulation result is not being produced in this model. Help is needed. This model focuses on energy saving.

[Sam Chak]

You did not post the transfer function Gp(s) or the complete Simulink model. Assuming the input to the transfer function is nonzero (a constant), then mathematically, if Gp(s) contains a factor s in the numerator (i.e., a zero at s = 0), the output of the transfer function block will be zero for a constant (DC) input.

[Nabiyev Muslim]

[Nabiyev Muslim]

bu yerda model keltirilgan. model nasos stansiyasi uchun boshqaruv tizimi uchun qo'llaniladi. noaniq mantiq boshqaruvchisi orqali boshqarish rejalashtirilgan. noaniq mantiqning ikkita kirish va bitta chiqish qiymatlarga ega. qoidalar 5x5=25 asosida kiritilgan xatolikni topolmayapman keyingi rasmda simulatsiyani ham keltiraman

[Nabiyev Muslim]

[Nabiyev Muslim]

ekspertlardan iltimos qilardim shu modelim ishlashida yordam berishlarini. shu modelni katta quvvatli nasos stansiyalarida qo'llab elektr energiya tejash ko'zda tutilgan. agar imkoni bo'lsa bu modelni yana qanday takomillashtirish mumkin maslahat beringizlar. Uzbekistonda ham shu nasos stansiyasi sohasida yangilik kiritib energiya va resurs tejamkorligiga erishmoqchiman

Answer 1

[Sam Chak]

Hi @Nabiyev Muslim

I cannot help you with all aspects of the problem due to the lack of certain info, and the original plant system is nonlinearized with saturation blocks. However, you can explore the following design approach and adjust the master control gain Kc​ to ensure that the outputs of Ga and G2​ remain within the signal constraints.

Since the four individual subsystems (G1 to G4) are stable 1st-order systems, the overall plant (Gp​) behaves as a 4th-order system, similar to a 1st-order system. The auxiliary compensator (Ga​) uses the characteristics of Gp​ to reshape its response. A PI controller (Gc) has been found to be sufficient for the control task. If a fuzzy controller is required in your research, the PI controller can be fuzzified to maintain the effectiveness of the designed control strategy.

% individual subsystems
G1  = tf(5, [0.003, 1]);
G2  = tf(29.6, [0.3, 1]);
G3  = tf(0.0622, [0.15, 1]);
G4  = tf(1000, [2, 1]);
G5  = tf(0.0001);

% plant
Gp  = minreal(series(G1, series(G2, series(G3, series(G4, G5)))))

Gp =
 
                     3409
  ------------------------------------------
  s^4 + 343.8 s^3 + 3527 s^2 + 9085 s + 3704
 
Continuous-time transfer function.

[num, den]  = tfdata(Gp, 'v');
pp  = pole(Gp)

pp = 4×1

-333.3333 -6.6667 -3.3333 -0.5000

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

% auxiliary compensator
Ga  = zpk([pp(2), pp(3)], [pp(1), pp(1)], pp(4)*pp(1)^3/num(5))

Ga =
 
  5431.5 (s+6.667) (s+3.333)
  --------------------------
         (s+333.3)^2
 
Continuous-time zero/pole/gain model.

% cascaded system Ga*Gp with the dominant pole at s = pp(4)
Gap = (minreal(series(Ga, Gp)))

Gap =
 
      1.8519e+07
  -------------------
  (s+333.3)^3 (s+0.5)
 
Continuous-time zero/pole/gain model.

dcgain(Gap)

ans = 1.0000

[y1, t1] = step(Gp, 20);
[y2, t2] = step(Gap, 20);

% plot Open-loop step response
figure
yyaxis left
plot(t1, y1)
ylabel('y_{Gp}(t)')
yyaxis right
plot(t2, y2)
ylabel('y_{Gap}(t)')
grid on
legend('Gp', 'Gap', 'location', 'east')
xlabel('Time (seconds)')
title('Open-loop step response')

% PI controller for Gp (without Ga)
Kc1 = 1;
Gc1 = pid(1, -pp(4))/(-pp(4))*Kc1

Gc1 =
 
             1 
  Kp + Ki * ---
             s 

  with Kp = 2, Ki = 1
 
Continuous-time PI controller in parallel form.

% PI controller for Gap (with Ga)
Kc2 = 2;
Gc2 = pid(1, -pp(4))/(-pp(4))*Kc2

Gc2 =
 
             1 
  Kp + Ki * ---
             s 

  with Kp = 4, Ki = 2
 
Continuous-time PI controller in parallel form.

Answer 2

[Nabiyev Muslim]

rahmat bu modelni ham ishlatib kuraman va huddi shu fayl uchun noaniq mantiq boshqaruvchisini qullab kuraman. telegram messengeri orqali gaplashsak buladimi. @muslim_nabiyev shu manzilda bulardim bir real ishlaydigan model qilishimga yordam bera olasizmi vaqtingizni olib quymasam. telegramdan yozsangiz bemalol fikrlar modellar almashib ilmiy yunalishda katta loyixa qilishimga yordam bering itimos qilaman.

[Walter Roberson]

Approximate translation of @Nabiyev Muslim

Thank you, I will try this model and use the fuzzy logic controller for the same file. Can we talk via telegram messenger? @muslim_nabiyev I was at this address, can you help me make a real working model if I don't take up your time? If you write on telegram, feel free to exchange ideas and models, help me make a big project in the scientific direction, I hope.