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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


Controlling Harmonics

To improve the quality of power supply, to improve the operation reliability of equipment and to reduce the economic losses caused by equipment misoperation
To reduce line heating, to reduce insulation aging and to improve electricity safety and reliability
To reduce the resonance probability of the compensation capacitor, and to improve the electricity safety and reliability To reduce the electromagnetic interference caused by harmonics and to ensure the normal operation of the communication system

To meet the requirements of national standards

Controlling Three-phase Imbalance

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

Controlling Voltage Deviation

To avoid damage to equipment caused by too high or too low voltage

5. High Power Density

The YDK-APF/SVG series with modular design can be adapted to 600 wide cabinets, 600 deep cabinets, 600 X 600 deep cabinets and various cabinets of larger size. The power of the whole machine can reach 900A/600kvar, while the mainstream index of the industry is less than 600A/400kvar. The higher power density can save floor space and cost for users.

For SVG, the rated output power is calculated according to the complete non-reactive power. It can also compensate the single-phase load current with full power, maintain the three-phase current balance on the grid side, and compensate the low-order harmonics within 13 times with half the power. The remaining power is used for reactive power compensation, total output power

6. Low Loss

Thanks to the good command of power electronics high-speed switching devices, the YDK-APF/SVG has an active loss is less than 2.5%, while the industry mainstream index is less than 3%~4%. Active power loss is crucial to those industries with the large-scale application of SVG, such as the State Grid.

7. Low Noise Level

YDK-APF/SVG series uses high-quality soft magnetic reactors with scientific air duct design. The noise of the whole machine at full-load working dose not exceed 60dB, while the industry mainstream index is less than 70dB. The mute is crucial for users to get the best experience of the product!

8. High Current Loop Bandwidth

YDK-APF/SVG was the first one in China to achieve quasi- natural sampling and contact control, with an equivalent switching frequency of 80 kHz, and a current loop bandwidth of 4K Hz, while the mainstream indicators in the industry are 20KHz/1KHz respectively. Its speed of suppression disturbance is more than four times that of other products in the same industry. If the equipment has a higher current loop bandwidth, the protection will be timelier. It can work stably in extremely bad situations, and not produce resonances when connected in parallel with pure capacitors.

Performance Index