APF active filterDetailed product description：

model
APF-0.4-400-3L meaning: APF active, 0.4 voltage, 400 harmonic current A, 3L three-phase three wire, 4L three wire four wire
APF active filter

working principle
Filtering principle
Real time current signals are collected through external transformers CT, and harmonic components are separated through internal detection circuits. IGBT power converters are used to generate compensation currents that are equal in magnitude and opposite in phase to the system's harmonics, achieving the function of filtering out harmonics.
The output compensation current dynamically changes based on the harmonic amount of the system, so there will be no issue of overcompensation. In addition, there is an internal overload protection function, which can automatically limit the output to 100% rated capacity when the harmonic amount of the system is greater than the filter capacity, without causing filter overload.
Principle of reactive power compensation
It is possible to perform dynamic reactive power compensation while filtering out harmonics through parameter settings.
Based on the reactive power of the detection system, a capacitive or inductive fundamental current is generated through an IGBT power converter to achieve dynamic reactive power compensation, with the target value of reactive power compensation
It can be set through the control panel.
The reactive power compensation current of the system dynamically changes according to the reactive power demand, and there will be no overcompensation. Flexible reactive power compensation will not generate surge surges.
Principles of Internal Control
After the isolation switch is closed, the DC bus capacitor is first charged through a pre charging resistor, which lasts for a few seconds to prevent instantaneous impact on the DC bus capacitor after power on. When the bus voltage Udc reaches the predetermined value, the main contactor closes.
The DC bus capacitor serves as an energy storage component, providing energy for compensating current output through IGBT inverters and internal reactors.
Real time acquisition of current signals through external CT is sent to the signal conditioning circuit, and then sent to the FPGA controller. The controller separates the fundamental components and extracts all harmonics; The controller will compare the collected harmonic components with the compensation current already emitted to obtain the difference as a real-time compensation signal output to the drive circuit, triggering the IGBT converter to generate harmonic currents with opposite phases to the load harmonic currents and inject them into the power grid, achieving the function of filtering out harmonics.

Characteristics and Applications of APF Active Filters
3L application areas and characteristics
3L active power filter suitable for industrial large capacity loads
For rectifiers, frequency converters, large UPS, medium frequency furnaces, electric arc furnaces, and welding machines. We have launched the 3L series active power filter for large capacity nonlinear loads in industries such as chemical engineering.
The 3L series active power filter has unprecedented filtering capability, which can simultaneously filter out harmonics of the 2nd to 50th order. The filtering capability can reach over 97%, and the complete compensation time for harmonics with step changes is less than 10ms.
The 3L series active power filter can be operated in parallel with multiple units, making it fully suitable for various situations in the industrial field. It is the best solution for harmonic control of large capacity nonlinear loads in industrial applications.
4L application areas and characteristics
4L active power filter suitable for civilian use
Fluorescent lamps, computers UPS、 Elevators, variable frequency air conditioners, and other devices not only seriously pollute the power grid, but also generate third harmonics that superimpose on the neutral line, causing it to heat up and posing a serious threat to the safety of the distribution system. To address commercial hybrid loads, the 4L series active power filter has been launched.
4L can completely eliminate the neutral line current caused by the third harmonic, and can eliminate all or selected harmonics within the range of 2-50. It has communication function and can be easily connected to the user's existing communication system.
The 4L active power filter can operate in parallel with multiple units, making it safe and suitable for various situations in the civil field. It is an essential electrical equipment in commercial building distribution systems and other civil fields.

Characteristics of APF active filter technology
Basic characteristics
Protection functions such as load short circuit, overvoltage, undervoltage, overcurrent, etc.  
Adopting high-definition, 5.7-inch Chinese color touch screen.  
It has the function of eliminating three-phase imbalance.  
Will not resonate with the system.  
Can manage standby function.  
It can filter only or filter and compensate reactive power simultaneously, and the priority order of functions can be set.  
The design selection is simple, without the need for detailed power grid analysis, only the measurement of the magnitude of harmonic currents is required.  
Parallel installation method, simple and convenient to install, easy to expand, and can accommodate multiple units in parallel.  
Can achieve parallel connection of different capacities.  
Implement fault and event records, and query historical records.

Product parameters

	3 lines	4 lines
Rated compensation current	100A-400A	50A-400A
input
Working voltage (V)	400V(-20%~+15%),690V(-20%~+15%)	400V(-20%~+15%)
Working frequency (Hz)	50/60	50/60
performance metrics
Filtering ability	THDI<3% (rated)	THDI<3% (rated)
Filter range	2~50 harmonics, eliminate all specified harmonics	2~50 harmonics, eliminate all specified harmonics
Adjustment of single harmonic compensation rate	Compensation current limit for each harmonic	Compensation current limit for each harmonic
Instantaneous response time	＜100us	＜100us
Full response time	＜10ms	＜10ms
Active power loss	<3% (rated)	<3% (rated)
Correct three-phase imbalance	have	have
Reactive power compensation function	Yes, power factor can be set	Yes, power factor can be set
Overload function	Automatic current limiting at 100% rated output	Automatic current limiting at 100% rated output
switching frequency	20KHz	20KHz
Display and Operation
display interface	5.7-inch Chinese color touch screen	5.7-inch Chinese color touch screen
display status	Grid parameters such as current, voltage, power, and harmonic distortion rate	Grid parameters such as current, voltage, power, and harmonic distortion rate
communication	Modbus, RS485, TCP/IP Ethernet	Modbus, RS485, TCP/IP Ethernet
Input and output nodes	5 output nodes, 4 input nodes (customizable by users)	5 output nodes, 4 input nodes (customizable by users)
Product Configuration
Standalone operation	can	can
Parallel operation	Multiple parallel machines are allowed	Multiple parallel machines are allowed
environmental conditions