Load disturbance response in Simulink - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to simulate the load disturbance response in Simulink.

Simulink

sim('load_disturbance_model', [1])

Drag options to blanks, or click blank then click option'

A'20'

B'30'

C'40'

D'10'

Attempts:

3 left

💡 Hint

Common Mistakes

Using too short simulation time like 10 seconds.

Forgetting to put the simulation time as a string.

The simulation time is set to 20 seconds to observe the load disturbance response clearly.

2fill in blank

medium

Complete the code to add a step disturbance input at 5 seconds.

Simulink

disturbance = stepinput('Step', 'Time', [1], 'Amplitude', 1);

Drag options to blanks, or click blank then click option'

A5

B3

C7

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Setting disturbance time too early like 3 seconds.

Using a time value not matching the simulation duration.

The disturbance step is applied at 5 seconds to observe the system's reaction.

3fill in blank

hard

Fix the error in the code to correctly plot the load disturbance response.

Simulink

plot(simout.time, [1].signals.values);

Drag options to blanks, or click blank then click option'

Adisturbance

Bload_response

Csimout

Dresponse

Attempts:

3 left

💡 Hint

Common Mistakes

Using the disturbance variable instead of the response.

Using the simulation output object directly without accessing signals.

The variable load_response contains the system output to plot against time.

4fill in blank

hard

Fill both blanks to create a dictionary of response times and overshoot values.

Simulink

response_metrics = [1](time=load_response.time, [2]=load_response.signals.values);

Drag options to blanks, or click blank then click option'

Adict

Blist

Covershoot

Dvalues

Attempts:

3 left

💡 Hint

Common Mistakes

Using a list instead of a dictionary.

Using incorrect keys like 'overshoot' instead of 'values'.

We use a dictionary to map 'time' to the time vector and 'values' to the response values.

5fill in blank

hard

Fill all three blanks to filter response values greater than 0.5 and create a new dictionary.

Simulink

filtered_response = {k: v for k, v in response_metrics.items() if v[1] [2] and k [3] 'values'}

Drag options to blanks, or click blank then click option'

A>

B0.5

C!=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using equality instead of inequality for filtering.

Mixing up key and value in the condition.

This comprehension keeps items where the value is greater than 0.5 and the key is not 'values'.

Practice

1. What does the load disturbance response in Simulink primarily show?

easy

A. How the system reacts to sudden changes in load

B. The initial setup of the Simulink model

C. The color scheme of the Scope block

D. The size of the Step block

Solution

1. Step 1: Understand the concept of load disturbance

   Load disturbance response shows how a system behaves when the load changes suddenly.

2. Step 2: Identify what Simulink simulates

   Simulink uses Step blocks to create load changes and Scope blocks to observe system reactions.

3. Final Answer:

   How the system reacts to sudden changes in load -> Option A

4. Quick Check:

   Load disturbance response = system reaction to load change [OK]

Hint: Load disturbance = system reaction to load change [OK]

Common Mistakes:

• Confusing load disturbance with model setup
• Thinking it shows block colors or sizes
• Mixing disturbance with input signals

2. Which Simulink block is typically used to simulate a sudden load disturbance?

easy

A. Integrator block

B. Gain block

C. Step block

D. Scope block

Solution

1. Step 1: Identify blocks that create input changes

   The Step block creates a sudden change in input value, simulating a disturbance.

2. Step 2: Differentiate from other blocks

   Gain changes signal magnitude, Integrator accumulates signals, Scope only displays signals.

3. Final Answer:

   Step block -> Option C

4. Quick Check:

   Step block simulates sudden changes [OK]

Hint: Step block creates sudden input changes [OK]

Common Mistakes:

• Choosing Scope block which only displays signals
• Confusing Gain block with disturbance source
• Selecting Integrator which accumulates signals

3. Given this Simulink setup: a Step block with step time 5 seconds connected to a system, what will the Scope show at 6 seconds?

medium

A. The system output before disturbance

B. The system output after disturbance

C. No output because Step block is inactive

D. A constant zero output

Solution

1. Step 1: Understand Step block timing

   The Step block changes its output at 5 seconds, causing a disturbance.

2. Step 2: Analyze system output at 6 seconds

   At 6 seconds, the system has reacted to the disturbance, so output reflects post-disturbance state.

3. Final Answer:

   The system output after disturbance -> Option B

4. Quick Check:

   Step time 5s means output changes after 5s [OK]

Hint: Output after step time shows disturbance effect [OK]

Common Mistakes:

• Thinking output stays same before and after step
• Assuming Step block inactive after step time
• Confusing zero output with disturbance

4. You created a load disturbance simulation but the Scope shows a flat line. What is the most likely error?

medium

A. Scope block is not connected to any signal

B. Integrator block is missing

C. Gain block value is zero

D. Step block step time is set after simulation end time

Solution

1. Step 1: Check Step block timing

   If step time is after simulation ends, disturbance never occurs, so output stays flat.

2. Step 2: Verify simulation setup

   Other options may cause issues but a flat line despite disturbance usually means no disturbance triggered.

3. Final Answer:

   Step block step time is set after simulation end time -> Option D

4. Quick Check:

   Step time after sim end = no disturbance [OK]

Hint: Step time must be within simulation time [OK]

Common Mistakes:

• Ignoring simulation end time vs step time
• Assuming Scope connection is always correct
• Thinking Gain or Integrator cause flat line

5. You want to design a system in Simulink that quickly recovers from a load disturbance at 3 seconds. Which approach helps achieve this?

hard

A. Use a Step block at 3 seconds and tune controller gains for fast response

B. Remove the Step block and use a constant input

C. Increase simulation time to 10 seconds without changing blocks

D. Use only Scope blocks without any disturbance

Solution

1. Step 1: Introduce disturbance at correct time

   Use a Step block at 3 seconds to simulate the load disturbance.

2. Step 2: Tune controller gains for fast recovery

   Adjust controller parameters to make system respond quickly and stabilize after disturbance.

3. Final Answer:

   Use a Step block at 3 seconds and tune controller gains for fast response -> Option A

4. Quick Check:

   Disturbance + tuning = fast recovery [OK]

Hint: Disturbance + controller tuning = fast recovery [OK]

Common Mistakes:

• Removing disturbance removes test scenario
• Increasing time alone doesn't improve response
• Using only Scope blocks can't fix system behavior