in my simulink,used for voltage stabilization which used dvr in flc,here the output have some issues the vload and vinj? so can u help me, vload would be proper sine wave?

Hi @Faria,

I can see you followed my advice and changed your powergui from 1e-5 seconds to 5e-6 seconds but looking at your latest screenshot of waveforms, Vinj is still showing the same noisy pattern and Vload still has distortion. That's frustrating.

Looking at your Vinj waveform, those jagged, noisy patterns are classic unfiltered PWM switching harmonics which means that your DVR is outputting raw PWM signals directly, and all that high-frequency noise is going straight into your injection point and bleeding into your load voltage.

Here's what you need to do. Keep your powergui at 5e-6 seconds as it is - open up that DVR subsystem and try adding

an LC filter inside it. So, double-click on the cyan DVR block in your main model. This will open the subsystem so you can see what's inside - you'll see your inverter, fuzzy logic controller, PWM generator, and other components.

Now you need to find where the inverter output connects to the rest of the circuit. This is the critical spot where you'll add the filter. According to MathWorks documentation, for three-phase inverter systems, you should use the Three-Phase Series RLC Branch block. Go to your Simulink Library Browser and navigate to Simscape > Power Systems > Passive. Look for "Three-Phase Series RLC Branch" and drag one of these blocks into your DVR subsystem.

Double-click on the Three-Phase Series RLC Branch block to configure it. Set the Branch type parameter to "LC" - this gives you just the inductor and capacitor without a resistor. For the inductance, set it to 0.002 (that's 2 millihenries). For the capacitance, set it to 20e-6 (that's 20 microfarads). These values are typical for DVR applications based on MathWorks power electronics examples.

Connect this LC branch in series between your inverter output and wherever that connects to your injection transformer. The LC filter works by passing your fundamental frequency (50 or 60 Hz) while blocking the high-frequency PWM switching harmonics. The cutoff frequency of this filter will be around 1-2 kHz, which is perfect - well above your fundamental but well below your PWM switching frequency.

Now here's something else from MathWorks documentation - if after adding the LC filter you see any ringing or oscillations in your Vinj, you might need to add a small damping resistor. You can do this by changing the Branch type from "LC" to "RLC" and setting the Resistance to around 0.5 ohms. This prevents the filter itself from oscillating, but try it without the resistor first.

While you're inside the DVR subsystem, double-check your Fuzzy Logic Controller and PWM Generator blocks. Both should be set to discrete-time mode with sample time 5e-6 - not inherited and not continuous. They need to match your powergui timing.

For your main Configuration Parameters, make sure you have Fixed-step as the solver type, use either ode1 or discrete as the solver, set the fixed-step size to 5e-6, and make sure "Treat each discrete rate as a separate task" is unchecked.

The reason this filter is so essential comes from basic power electronics principles. Your PWM inverter generates the desired 50/60 Hz sine wave plus a whole bunch of harmonics at the switching frequency and its multiples. Without a filter, all of those harmonics show up in your injection voltage. An LC filter is specifically designed to smooth out these harmonics and give you a clean sine wave output.

After you add this LC filter inside the DVR subsystem, run your simulation again. You should see Vinj transform from those noisy, jagged waveforms into smooth three-phase sine waves. And because Vinj feeds into Vload through your series connection, Vload will automatically become perfectly sinusoidal too.

The key thing to understand is that adjusting sample times and solver settings outside the DVR subsystem won't fix this issue by themselves. You have to actually modify the circuit inside the DVR by adding the filter components. The sample time controls how often Simulink calculates values, but the LC filter is the actual electrical component that physically smooths the waveform.

Try adding this filter and let me know what happens.

Hi @Faria,

I understand you’d like to continue this discussion directly, but MathWorks policy doesn’t allow sharing personal contact details or continuing support through email. It’s best — and actually required — to keep all technical help on the forum so others can learn from it too.

Now let me address your latest comments.

I went through your latest plots carefully. You’ve definitely made progress — the setup looks closer to what it should be — but the waveforms still show the same issue Umar mentioned earlier. The Vinj trace is still noisy and jagged, which means the inverter’s PWM switching harmonics are not being fully filtered out. The short burst around 0.12–0.16 seconds looks like a resonance effect, probably because the RLC filter isn’t placed or tuned correctly.

In plain terms, the inverter output is still feeding high-frequency PWM components into the system. This usually happens when the filter is wired incorrectly or the scope is measuring the wrong node. Please make sure your RLC branch is in series between the inverter output and the injection transformer, not in parallel. Also check that your scope is connected after the filter.

If the connection is correct, try setting a small damping resistance (around 0.5 ohms) in the RLC branch to reduce ringing. The sample time change to 5e-6 s was the right move — keep that setting as is. Once the filter is properly placed and tuned, Vinj should become a clean sine wave and the load voltage will smooth out automatically.

If you can, please post a screenshot of your DVR subsystem wiring and the RLC parameters on the forum — it’ll be easier to spot what’s missing.

Hope this helps!