Harmonic Mitigation Expert---Active Power Filter

The main hazards of harmonics:
Increase the load of power facilities, reduce the power factor of the system, reduce the effective capacity and efficiency of power generation, transmission and power consumption equipment, resulting in equipment waste, line waste and power loss;
Causes the resonance of reactive power compensation capacitors and the amplification of harmonic currents, resulting in capacitor banks being damaged or unable to be put into operation due to overcurrent or overvoltage;
· The pulsating torque causes the motor to vibrate, which affects the product quality and motor life;
· Due to eddy current and skin effect, the motor, transformer, transmission line, etc. produce additional power loss and overheat, waste electric energy and accelerate insulation aging;
· Harmonic voltage increases the electric field strength of the insulating medium in proportion to its peak voltage, reducing the service life of the equipment;
· The zero-sequence (multiple times of 3) harmonic current will cause the neutral line of the three-phase four-wire system to be overloaded, and generate circulating currents in the delta-connected transformer windings, causing the winding current to exceed the rated value, and even cause an accident in severe cases;
· Harmonics will change the action characteristics of the protection relay, cause the malfunction of the relay protection facilities, and cause the automatic devices such as relay protection to work disorderly;
· Harmonic variation changes the rate of change and peak value of voltage or current, delays arc extinguishing, and affects the breaking capacity of circuit breakers;
· Make metering instruments, especially inductive energy meters, produce measurement errors;
· Interfere with adjacent power electronic equipment, industrial control equipment and communication equipment, affecting the normal operation of the equipment.

Features:
1. High filtering accuracy, the harmonic current filtering rate can reach more than 97%;
2. Wide filtering range, filtering times: 2--50 harmonics and inter-harmonics;
3. Fast response to load fluctuations, the response time is 1us;
4. Dynamically inject current to suppress harmonics and compensate power factor;
5. Will not resonate with the system;
6. Multiple units can be combined to expand capacity;
7. Suppress system overvoltage and improve system voltage stability
8. Damping the power oscillation of the power system;
9. It can suppress voltage flicker, compensate for three-phase unbalance, and improve power factor;
10. The system has strong self-protection and stability.

Harmonic control economic benefits:
1. Energy saving 5% to 8%;
2. Derating reduces the investment in transformers, circuit breakers and cables;
3. Improve productivity and maintain continuous power supply.

The picture below is of a customer in Southeast Asia who installed ZDDQ APF on site, and the harmonic current is almost perfectly compensated.