Can Coepower APF Mitigate Even Order Harmonics? - China Active Harmonic Filter, SVG Static Var Generator, Active Harmonic Mitigator AHM Suppliers, Manufacturers, Factory

Can Coepower APF Mitigate Even Order Harmonics?

This is a site that uses high-power heating furnace equipment for production. According to customer feedback: There are a total of 3 heating furnaces in the plant, all installed on the 10/0.4KV side of the on-site transformer, with a transformer capacity of 2500KVA. Due to the use of controllable heating furnace equipment, serious harmonic distortion problems have occurred in the power system during the production of the furnace, affecting the normal operation of the equipment.

Due to the appearance of a large amount of harmonic current, the load of furnace #2 on-site corresponds to the upstream circuit breaker in the transformer, which frequently trips. The customer has upgraded the original rated current 1000A circuit breaker to 1250A. At the same time, there is a fault in the reactive power compensation cabinet inside the transformer on-site. The significant harmonic distortion seriously endangers the stability of the on-site power distribution network and the electrical safety of the plant equipment.

After data testing and site survey, we installed active power filters (600A) in the systems of furnaces #1 and #2 at the customer’s site for harmonic control. The equipment is running normally, and the on-site control effect is good.

Effect Analysis

Current data

Before the active power filter was turned on, the load current waveform significantly deviated from the sine waveform, with the effective values of phase A/B/C currents around 610A.

After the active power filter was turned on, the load current waveform was restored to a sine waveform, with the effective values of phase A/B/C currents dropping to around 540A.

From the perspective of the current waveform, the treatment effect of the equipment is obvious, and there is a significant improvement in the system’s load current waveform.

THDI analysis

Before the active power filter was turned on, the total current harmonic distortion rate of phases A/B/C in the system reached 66%. The main harmonic distortion frequencies were the 2nd, 4th, 8th, and 10th harmonics, with the most severe harmonic distortions being at the 2nd and 4th harmonics.

After the active power filter was turned on, the total current harmonic distortion rate of phases A/B/C in the system showed a significant decrease, dropping from the pre-treatment level of 66% to 6.9%. The main harmonic distortion frequencies of the 2nd, 4th, and 8th harmonics were significantly suppressed.

TDHV analysis

The harmonic distortion of the system voltage was very slight before the APF equipment was turned on and did not change significantly after the equipment was turned on.

Analysis of each harmonic

Before the active power filter was turned on, the total harmonic current distortion rate of the load current was around 66%, with the main harmonic distortion frequencies being the 2nd, 4th, and 8th harmonics.

Specifically:

2nd harmonic current: