UPS & Inverter Harmonics Simulation
Effect of harmonics on UPS and inverter systems
🔌 UPS / Inverter Power System
50 Hz
Load
📈 UPS / Inverter Waveform
● Fundamental 50 Hz ● Distorted waveform
The cyan waveform contains harmonic components and therefore deviates from the ideal sinusoidal fundamental waveform.
📊 Harmonic Measurements
⚠ Effects of Harmonics
🔥 Heating
Harmonic current can increase RMS current and therefore increase conductor, transformer and semiconductor losses.
⚡ RMS Current
The RMS current contains contributions from the fundamental and harmonic components.
🔊 Transformer Noise
Harmonic currents can contribute to additional magnetic vibration and transformer noise.
🔋 Battery Stress
Higher losses and temperature can increase stress on UPS components and associated batteries.
💻 Electronic Equipment
Excessive power-quality distortion can affect sensitive electronic equipment.
📉 Efficiency
Additional harmonic losses can reduce system efficiency and increase operating temperature.
🛠 Harmonic Mitigation
1. Passive LC Filter: Provides a low-impedance path for selected harmonic frequencies.
2. Active Harmonic Filter: Detects harmonic current and generates compensating current.
3. Low-THD UPS: Modern UPS systems can use low-harmonic rectifier technology.
4. Proper UPS Sizing: Avoid continuously operating the UPS near its maximum rating.
5. Load Management: Distribute nonlinear loads appropriately.
6. Power Quality Monitoring: Measure voltage THD, current THD, RMS current, loading and temperature.
📐 Important Relationship
The total RMS current is the root-sum-square of the fundamental and harmonic current components.