Power Projects

Effect of shunt FACTS devices
Shunt FACTS devices work by injecting or absorbing reactive power.
They do not change system impedance.
They only react to it.

When a STATCOM or SVC is connected to a weak bus:
• The same MVAR produces a large voltage correction
• Voltage regulation looks very effective

When the same device is connected to a strong bus:
• The same MVAR produces only a small voltage change
• Voltage regulation appears weak

This leads to a very important conclusion. Effectiveness of shunt FACTS devices is inversely proportional to system strength.

In simple words:
• Weaker system → higher voltage sensitivity → better visible control
• Stronger system → lower voltage sensitivity → limited visible control

Common misconception
Many assume that FACTS devices perform better in strong systems.
That is incorrect.
Strong systems already hold voltage stiffly.
They do not “respond” much to reactive power injection.

Weak systems need support.
That is where FACTS devices show their real value.

Practical implications
This directly affects:
• Location selection of STATCOM and SVC
• MVAR sizing
• Investment decisions
• Grid code compliance

Installing a large STATCOM at a strong grid node may not give expected voltage improvement. The same device placed at a weak node can dramatically improve voltage profile.

Key takeaways
• Short circuit current defines system strength
• Voltage variation is higher in weak systems
• Shunt FACTS devices control voltage using reactive power
• Their effectiveness increases as system strength reduces
• Proper placement matters more than device size

This is not a software result.
This is pure system physics.

If you understand this clearly,
you are thinking like a power system engineer, not just running studies.

𝗘𝗳𝗳𝗲𝗰𝘁𝗶𝘃𝗲𝗻𝗲𝘀𝘀 𝗼𝗳 𝗦𝗵𝘂𝗻𝘁 𝗙𝗔𝗖𝗧𝗦 𝗗𝗲𝘃𝗶𝗰𝗲𝘀 — 𝗪𝗵𝘆 𝗦𝘆𝘀𝘁𝗲𝗺 𝗦𝘁𝗿𝗲𝗻𝗴𝘁𝗵 𝗠𝗮𝘁𝘁𝗲𝗿𝘀

This is one topic where many engineers get confused.

Shunt FACTS devices like SVC and STATCOM are widely used for voltage control.
But their effectiveness is not the same everywhere in the network. The key reason is system strength.

What do we mean by system strength?
System strength is directly linked to short circuit current.
Higher short circuit current means a stronger bus.
Lower short circuit current means a weaker bus.

A strong bus has:
• Low Thevenin impedance
• High fault level
• Small voltage deviation for load changes

A weak bus has:
• High impedance
• Low fault level
• Large voltage deviation for the same disturbance

Why voltage varies more in weak systems. Voltage change is proportional to reactive power change and system impedance.

If the impedance is high:
• Even a small reactive power injection or absorption causes a large voltage change
If the impedance is low:
• The same reactive power change causes only a small voltage change
That is basic power system behaviour.

As the year comes to a close, we reflect with gratitude on the partnerships, progress, and achievements that shaped our journey. We sincerely thank our clients, collaborators, and dedicated team for your trust and continued support.

Your commitment motivates us to keep striving for excellence and innovation.
May this Christmas bring joy, peace, and new energy into your lives, and may the New Year open doors to greater opportunities and success.

We look forward to strengthening our relationships and achieving even more together in the coming year.

✨ Merry Christmas and Happy Vacation