Working Principle of YDK-APF/SVG Series

Active Power Filter (APF) compensates for any harmonics ranged from 2nd to 50th. Static Var Generator (SVG) compensates for reactive power, three-phase current imbalance, and harmonics below 13th. YDK- APF/SVG is essentially a controllable current source, which can emit any current waveform specified by the user, to achieve an ideal compensation effect, and can also indirectly improve the voltage quality by improving the quality of current. Therefore YDK-APF/SVG is a set of comprehensive power management devices to fully solve the power quality problems.

YDK-APF/SVG monitors the grid current or load current in real time through the external transformer CT.
The controller extracts the fundamental current of the load and each harmonic through fast Fourier transform, and obtains active, reactive, negative sequence via DQ rotation coordinates. Then, it generates the compensation current with the same magnitude and the opposite phase into the grid through the IGBT converter, improving the power quality of the grid side.

Leading Advantages
Strong Anti-pollution Performance
Easy Filed Installation
Unlimited Combination
Controlling Reactive Power
Controlling Harmonics
Controlling Three-phase Imbalance
Controlling Voltage Deviation
High Power Density
Low Loss
Low Noise Level
High Current Loop Bandwidth


1. Modularisation

Each module unit operates independently and no central controller is required. Any failed module will automatically exit. The rest of the modules will automatically bear the load on average under the nominal current. The whole machine will continue to work. It is very convenient for users to do the daily operation and maintenance.

According to the theory of the redundancy N+1, the reliability of equipment is increased by one order of magnitude for each level of redundancy. Such a modular structure especially meets the needs of customers with high power quality requirements.

2. Strong Anti-pollution Performance

All conductive elements except the fan, isolated from the outside, are suitable for severe dust, saline-alkali and humidity situations. The schematic diagram of the internal structure of the module is the below:

3. Easy Filed Installation

The user can select the upper bus wiring or the lower cable wiring, and also can select the load side or the grid side as the external current CT sampling point.

4. Unlimited Combination

APF, SVG and SC in different types and different specifications can be freely combined to have more rich functions. PF and SVG can also be used together with third party capacitor compensation, for example, 150A APF + 50A APF + 50K VAR SVG + 100K VAR TSC. Moreover, TDK-APF/SVG will never occur the resonance, and ensure the safe and reliable operation of the whole power grid system, regardless of the form of the third-party compensation capacitor or of the passive filtering.

The principle of combination and the realized function are shown in “More Economical Compensation Scheme”.

Improve power quality benefits for users

Controlling Reactive Power

To reduce user's own electricity expenses
To ensure that the power factor reaches the national standard, avoiding the power rate electric bill penalty caused by the low power factor
To reduce line loss and voltage drop
To improve the actual capacity of transformers and generators