APF active power filter

•For rotating generators and motors, additional losses are caused by harmonic currents or harmonic voltages in the stator windings, rotor circuits and iron cores, which reduces the efficiency of power generation, transmission and electrical equipment.

•Harmonic voltage can in many cases make sine waves sharper, which not only increases hysteresis and eddy current losses in electrical equipment such as motors, transformers, capacitors, etc., but also increases the electrical load on insulating materials.

Since the loads of motors, transformers, power capacitors, cables, etc. change frequently, it is easier to create series or parallel resonant states with a large number of harmonic sources contained in the power grid, which form harmonic oscillations, generating overvoltage or overcurrent, which compromises the safe operation of motors, transformers and other loads and power systems, leading to accidents in the transmission and distribution of electrical power.

•Harmonics in the electrical system can cause errors in the measuring instruments that prevent correct instructions and measurements from being carried out. When a circuit breaker interrupts current with high harmonic content, the breaking capacity of the circuit breaker is greatly reduced, resulting in arcing, short circuiting, and even explosion of the circuit breaker.

-The presence of harmonics can easily cause malfunction or failure of various electrical protection and automatic devices, as well as audio interference in the communication system, which, if serious problems occur, can threaten communication equipment and personal safety.

The Active Power Filter (APF) is connected to the mains in parallel. It can detect the voltage and current at the compensation point in real time. After calculations by the control unit, a wideband pulse modulation signal is used to drive the IGBT-module. APF injects a current into the network that is equal in magnitude but opposite in phase to the harmonic current in the network. These two harmonic currents cancel each other, thus performing the function of harmonic filtering, dynamically compensating reactive power and providing the desired source current.