Solar PV Powered Shunt Active Filter

Harmonic Mitigation Analysis using MATLAB/Simulink

We explain power quality compensation without shunt active filter and with shunt active filter (SAPF) using MATLAB/Simulink. The focus is on current harmonic reduction caused by nonlinear loads and how a PV-fed shunt active filter improves the system performance.

Solar PV powered Shunt active Filter in MATLAB

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🔍 Case 1: System Without Shunt Active Filter

⚙️ System Description

• 🔌 Grid Voltage: 415 V (line-to-line), 50 Hz

• 🧲 Source Impedance:

  • Resistance: 0.1 Ω

  • Inductance: 0.15 mH

• 🔄 Nonlinear Load:

  • Three-phase diode rectifier

  • RL load (R = 60 Ω, L = 20 mH)

This nonlinear load draws non-sinusoidal current, even though the grid voltage remains sinusoidal.

📊 Observations (Without SAPF)

• ✅ Grid voltage and load voltage are pure sinusoidal

• ❌ Grid current is highly distorted due to nonlinear load

• 📈 FFT analysis of source current shows:

  • THD ≈ 24.21% ❌

⚠️ According to IEEE standards, current THD should be less than 5%, so harmonic mitigation is required.

⚡ Need for Shunt Active Filter (SAPF)

Due to nonlinear loads, harmonics flow back to the source causing:

• Increased losses 🔥

• Poor power factor ⚠️

• Overheating of equipment 🔌

👉 Shunt Active Filter is introduced to inject compensating current, making the source current sinusoidal.

🔋 Case 2: System With Shunt Active Filter (SAPF)

🧠 SAPF Configuration

• 🔄 Three-phase VSI (Inverter)

• 🔋 DC-link Capacitor

• ☀️ PV-fed DC Source with Boost Converter

• 🎯 PI Controller for DC-link voltage regulation

📌 DC-link voltage is maintained between 500 V – 800 V, which is essential for effective harmonic compensation.

⚙️ Control Strategy

• SAPF measures grid current and load current

• Reference compensating current is generated

• VSI injects harmonic current in opposite phase

• Harmonics are cancelled at the source side

⏱️ SAPF Switching Operation

• 🕒 SAPF is activated at 0.04 – 0.05 seconds

• Before activation → distorted source current

• After activation → clean sinusoidal source current

📊 Observations (With SAPF)

🔌 Currents

• 🔹 Load current → remains distorted

• 🔹 SAPF current → injects harmonic components

• 🔹 Grid current → becomes nearly sinusoidal ✅

⚡ Voltages

• Grid voltage and load voltage remain unchanged

• No voltage distortion introduced by SAPF

📈 FFT & THD Comparison

Condition	Source Current THD
❌ Without SAPF	24.21 %
✅ With SAPF	0.59 %

🎯 THD reduced from 24.21% to 0.59%, well below IEEE limits.

🟢 Key Outcomes

✔️ Harmonics in source current are effectively eliminated✔️ Grid current becomes sinusoidal✔️ Power quality significantly improved✔️ PV-fed SAPF enables renewable-assisted compensation✔️ DC bus voltage remains stable under compensation

🎯 Purpose of Shunt Active Filter

• 🔄 Cancels load current harmonics

• ⚡ Improves source current quality

• 📉 Reduces THD to acceptable levels

• 🔋 Operates using renewable energy (PV-based DC link)

✅ Conclusion

This simulation clearly demonstrates that:

• Nonlinear loads cause severe current harmonics

• Shunt Active Filter is an effective solution for harmonic mitigation

• PV-fed SAPF provides a sustainable and efficient compensation technique

• Source current THD is reduced from 24.21% to 0.59%