Active Harmonic Filter is an intelligent harmonic control device. It combines modern power electronics technology and digital signal processing technology to detect harmonics and reactive components in the power grid in real time, dynamically generate reverse compensation current and inject it into the power grid, thereby eliminating harmonic pollution caused by nonlinear loads.
⚙️ Working Principle
1. 🔎Harmonic detection: AHF collects load current signals in real time through current transformers (CTs), converts analog signals into digital signals and transmits them to high-speed DSP processors.
2. 🧠Digital processing: DSP chips perform harmonic separation through algorithms such as fast Fourier transform (FFT), accurately calculate the content of each harmonic and reactive components, and generate compensation current instructions.
3. 🔄Dynamic compensation: The PWM control circuit generates a drive signal according to the instruction, controls the IGBT/IPM power module to generate compensation current with the detected harmonic (equal amplitude and opposite phase) and inject it into the power grid.
4. ⭕Closed-loop regulation: Continuously monitor system current changes, dynamically adjust compensation strategies with a high-frequency refresh rate of more than 20kHz, achieve millisecond-level real-time tracking compensation, and adapt to various load fluctuations.
🚩Technical features
✅Parallel access is adopted, which does not affect the operation of the main circuit. ✅It has triple functions of harmonic suppression (2nd~51th order), reactive power compensation and three-phase unbalance correction. ✅Equipped with adaptive algorithm, the compensation accuracy is more than 95%. ✅Fast response, with full response time <10ms
The device breaks through the inherent frequency limitation of traditional LC filters through active energy injection of power electronic devices, and can simultaneously solve complex power quality problems such as harmonic resonance, reactive power shortage, and three-phase imbalance.
Static Var Generator (SVG) is a power electronic device used to compensate the reactive power in electrical systems. It detects the load current on a real-time basis through an external CT (Current Transformer), and then it analyzes the load required reactive power current value by DSP control program, and uses PWM signal to drive the internal IGBT inverter to inject an opposite direction but same value current to offset the reactive current to meet the target power factor.
🌟 Main Functions
1️⃣ Power Factor Improvement ✨
By dynamically compensating for inductive/capacitive reactive power, SVG can stably improve the system power factor to above 0.95.
✅ Effectively reduce apparent power loss ✅ Improve the load capacity of equipment (e.g., transformers) ✅ Reduce line losses
2️⃣ Comprehensive Harmonic Control 🛡️
Adopting IGBT high-frequency modulation technology, the grid harmonics are filtered out during the compensation process (THD<5% for most cases).
✅ Avoid harmonic amplification from traditional LC resonance ✅ Meet requirements for sensitive scenarios
3️⃣ System Stability Control ⚡🚀
For severe reactive fluctuations (e.g., press machines, welding machines, rolling mills):
✅ 5-10ms ultra-fast compensation (100x faster than mechanical switches) ✅ Eliminate voltage flicker & equipment downtime risks ✅ Ensure continuous production line stability
4️⃣ Three-Phase Balance ⚖️
Real-time detection of reactive power differences + dynamic allocation via vector control.
✅ Prevent motor winding overheating ✅ Extend equipment lifespan
🌍 Applications
1️⃣ Industrial Field 🏭
Solve reactive power impacts from large motors, arc furnaces in metallurgy, steel, mining, chemical, etc.
📈 Maintain system PF ≥ 0.95 🛠️ Suppress voltage fluctuations during equipment start/stop
2️⃣ Power Transmission & Distribution 🔋
Enhance grid transmission capacity and help improve voltage stability in load centers.
3️⃣ New Energy Grid Connection 🌞💨
Adapt to fluctuating PV/wind generation:
🔁 Adjust reactive power flow in real-time 🌙 Help mitigate daytime/nighttime voltage fluctuation issues
4️⃣ Commercial & Public Facilities 🏢
Optimize power quality for buildings & communities:
💡 Compensate reactive power and harmonics from LEDs, air conditioners, elevators 💰 Reduce harmonic interference & electricity bills…
🌿 Empowering India’s Green Future 🌞💨
Thrilled to share that NLC India Ltd has secured a land
Thrilled to share that NLC India Ltd has secured a landmark 450 MW Wind-Solar Hybrid Power Project from NTPC Ltd, marking a significant stride in India’s renewable energy journey.
📍 Project Highlights:
300 MW to be developed in Bikaner, Rajasthan
150 MW in Bhuj, Gujarat
Power supply to NTPC for 25 years under a long-term PPA Scheduled commissioning within 24 months
This hybrid initiative leveraging both wind and solar underscores the growing momentum toward sustainable, reliable, and clean energy solutions across the country. Kudos to the teams at NLC India and NTPC for driving this transformative collaboration! ⚡Click here to know more…
Next, we will discuss about – How Hybrid Filters Are Powering a Cleaner Grid and Power infra in Kodagu by CESC-Chamundeshwari Electricity Supply Corporation