The new Reactive Power Compensation technology increased the Power Factor Of The Electric Arc Furnace to 0.95

The main equipment of a casting company is an electric arc furnace. The electric arc furnace is a typical harmonic source, generating a large amount of harmonics, which prevents the compensation capacitors from operating normally. The power factor fails to reach the required 0.9 or above. The temperature of the transformer reaches 75 degrees in summer, resulting in energy waste and shortened service life.

Based on the actual situation of the enterprise, our company has designed a complete filtering solution for arc furnace harmonic control. Considering the power factor, harmonic absorption requirements and background harmonics, a harmonic filtering device has been installed on the 10kV high-voltage side of the enterprise's transformer (8000kVA) to manage the harmonics.

Solution determined:

Due to the high harmonic content during the operation of the electric arc furnace, such as the second and third harmonics reaching 33.5% of the fundamental current, it has caused varying degrees of impact on the power grid, the equipment itself, and other users. Therefore, considering the power factor characteristics of the equipment and the equipment's own nature, this scheme adopts a filtering and reactive power compensation method: improving the stability of the power supply system; suppressing harmonic currents to reduce the harm caused by harmonics.

Considering that each filtering branch will not amplify high-order harmonics, from the test data, the main harmonic components are the 2nd, 3rd, 4th, and 5th harmonics. Among them, the 2nd and 3rd harmonics are the largest, and the voltage distortion is severe. Taking all these factors into consideration, the filter device is designed with two 2nd and 3rd harmonic filtering branches to absorb harmonics of 2nd and 3rd order and above. The scheme uses the simulation method to analyze whether non-characteristic frequency resonances occur when each circuit is put into operation, and finally determines the parameters of the circuits.

Correction effect:
1. The filtering compensation device has been put into operation. It automatically tracks the changes of various load equipment in the electric arc furnace, effectively filtering out all harmonics.
2. Before treatment, the total harmonic distortion rate (THD) of the voltage was seriously exceeding the limit of 4% stipulated by the national standard. After treatment, the total harmonic distortion rate (THD) dropped from the original 6.8% to 2.4%, and all harmonics met the standard requirements.
3. After treatment, the harmonic currents were effectively improved. The 2nd and 3rd harmonic currents that were severely exceeding the limit before treatment were absorbed at rates of over 80% after being put into operation, meeting the design requirements of the equipment.
4. After the filtering device was put into operation, the power factor of the system was significantly improved. The 10KV side of the power supply system increased from approximately 0.68 to above 0.95, effectively reducing the loss of the power supply lines.
5. After harmonic treatment, the temperature of the transformer decreased from the original 75 degrees to 50 degrees, saving a large amount of electricity and extending the service life of the transformer.
6. Through treatment, the power quality of the power supply was effectively improved, the utilization rate was increased, which is beneficial to the long-term safe and economic operation of the system and brings economic benefits.