MATLAB Simulation of Single Phase Shunt Active Filter

Power systems often face harmonic distortion and poor power quality due to non-linear loads. To tackle these challenges, a Single-Phase Shunt Active Filter is designed and simulated in MATLAB to ensure sinusoidal current flow and reduced Total Harmonic Distortion (THD).

🔎 Introduction to the Single-Phase System

• ⚡ Components Used: Single-phase voltage source, inductor, and inductive non-linear load

• 📉 Problem: Non-linear loads (e.g., rectifiers) distort source current

• 🎯 Observation: Instead of being sinusoidal, source current becomes non-sinusoidal with harmonics

MATLAB Simulation of Single Phase Shunt Active Filter

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⚠️ Challenges with Non-Linear Loads

• 📈 Increased harmonic distortion in source current

• 🔄 Higher reactive power consumption, degrading system performance

• 🛠 Solution: Use of a Shunt Active Filter to inject compensating currents and restore sinusoidal current

⚙️ Role of the Single-Phase Shunt Active Filter

• 🔌 Inverter: Controlled by a PI controller to generate compensating current

• 🔋 DC Capacitor: Maintains 700V to supply reactive power

• 📊 Function:

  • Compensates reactive power

  • Reduces harmonic distortion

  • Restores sinusoidal current in the system

🎛 Control Strategy with PI Controller

• 📏 Reference Tracking: Capacitor voltage is compared with reference (700V)

• 🧠 PI Controller: Adjusts inverter operation to maintain capacitor voltage

• 🔄 Process Steps:

  • Measure load current and source voltage

  • Generate delayed signal for real/reactive power calculation

  • Apply low-pass filter to extract compensating current

  • Drive inverter using reference current → inject compensating current

🔄 Generating the Compensating Current

• ⚡ Reference vs Actual Current: Inverter injects compensating current into system

• 📉 Effect:

  • Neutralizes harmonics

  • Balances reactive power

  • Ensures source current becomes sinusoidal despite non-linear load

📊 Simulation Results and Observations

• 🔋 Capacitor Voltage: Initially 670V → gradually charged to 700V

• ⚡ Current Waveforms:

  • Without filter → source current non-sinusoidal

  • With filter → source current sinusoidal

• 📉 Total Harmonic Distortion (THD):

  • Load current THD → initially very high

  • Source current THD after filtering → reduced to ~0.58%

🔌 Effect of Disconnecting the Filter

• ❌ Without Filter:

  • Source current THD = 46%

  • Load current THD = 36%

  • Both waveforms remain distorted

• ✅ With Filter:

  • Source current becomes sinusoidal

  • THD values significantly reduced

🏆 Conclusion

The MATLAB simulation confirms that the Single-Phase Shunt Active Filter:

• ⚡ Compensates reactive power

• 📉 Minimizes harmonic distortion

• 🎯 Restores sinusoidal source current even with non-linear loads

👉 Such filters are crucial in practical applications where power quality is critical, including industrial drives, renewable energy systems, and power electronics-based grids.