ACTIVE HARMONIC FILTERS
Active harmonic filters are parallel filters (which means the current doesn't go through the filter) that are used to reduce, or mitigate, harmonics to tolerable levels as defined by IEEE-519. Active filters use a set of transistors and capacitors to filter (or clean) the current wave by injecting inverse currents to cancel out the undesired harmonic components. Size is an immense factor in system design today and should be accounted for when deciding on what type of harmonic filter is right for you.
An increasing number of loads are non-linear, introducing harmonics into the power grid and thus significantly impairing the power quality. EPCOS PQSine is an active harmonic filter that effectively reduces the unwanted harmonics.
With the EPCOS PQSine series, TDK now offers an elegant and full automatic solution for many of the problems caused by harmonics and phase shifts. PQSine is connected to the grid in parallel with the load that is causing the harmonics. The heart of the new active harmonic filters is a controller based on a 32-bit digital signal processor (DSP) with a sampling rate of 48 kHz. With a response time of just 21 µs, PQSine offers class-leading performance. Its new selective drive control (SDC) algorithm is faster than conventional algorithms based on fast Fourier transform (FFT) analysis. Using the data determined in real time, PQSine feeds a compensation current into the grid, which cancels the non-linearity of the load current (Figure 2).
- Harmonic compensation up to 50th harmonic (individually selectable)
- Flicker compensation
- Ultra-fast reactive power compensation (inductive and capacitive)
- Load balancing between phases and unloaded neutral wire
- Compact design
- Modular system extendable
- Grid resonance detection
- Digital Control of FFT algorithm, intelligent FFT algorithm, instantaneous reactive algorithm
- Ethernet and Ether cat system for interconnection
- User-friendly menu operation
- High performance and reliability
- Insensitive to network conditions
- Overload protection & Internal short-circuit protection
- Overheating protection & Overvoltage and under voltage protection
- Inverter bridge protection & Resonance protection
- Fan fault alarm