Simscape voltage sensor block shows slightly lower value

Mike Buba

2026 10 15

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GridSource.slx

Hi,

I am experiencing a strange behaviour when using a simple model with voltage source and voltage sensor using Simscape library blocks.

I have set up the input voltage reference to 690 Vrms line-to-line, but after voltage sensor I am measuring slightly smaller voltage. The logical conclusion would be there is a series impedance somewhere in either Controlled Voltage Source (Three-Phase) or Current and Voltage Sensor (Three-Phase) block, but I do not know where.

Could anyone please clarify what is happening. I do not understand what I am seeing?! And can I make them show the same value?

Model is attached.

Regards, MB

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Sam Chak 2026-10-17，9:50

编辑：Sam Chak 2026-10-21，9:57

I don’t know where to start. However, a stable linear time-invariant (LTI) transfer function cannot perfectly track a pure sine-wave reference signal without additional inputs.

Assuming you can derive the equivalent or approximate transfer function of the system G(s) using Simulink Linearization Tool, when you pass a pure sine wave r(t) = A·sin(ω·t) into a stable LTI system G(s), the steady-state output will always take the form:

y(t) = A|G(jω)|·sin(ω·t + ∠G(jω))

where |G(jω)| is the magnitude and ∠G(jω) is the phase of the system.

For perfect tracking y(t) = r(t), two strict conditions must be met simultaneously at the specific frequency ω:

1. Magnitude condition: |G(jω)| = 1

2. Phase condition: ∠G(jω) = 0°

Perhaps other users can show you the mathematical solution for achieving perfect tracking, followed by the Simulink/Simscape config.

Torsten 2026-10-17，11:33

The values at t=0 already differ. Make sure they agree.

To this end, AI gives me this answer:

Transient Stabilization & Initialization

Simscape networks need to find an initial mathematical equilibrium at the very beginning of the simulation run (t=0).

The Issue: Unless configured otherwise, alternating current (AC) networks start at zero and experience a brief startup transient. Since RMS calculations rely on a sliding time window (typically one full cycle), the calculation will naturally look "diluted" or smaller during the first cycle because it includes t=0 data.
The Solution: Open your model's Solver Configuration block and check the option Start simulation from steady state. This forces Simscape to pre-calculate the AC steady state before time steps begin. Also, ensure your circuit has an Electrical Reference block properly connected to ground.