kVAH billing optimisation for highly dynamic loads in steel industries like EAF, rolling mills

The inPhase solution tackles high harmonics caused by non-linear loads and low power factors due to dynamic loads.

InPhase excels in addressing power system challenges in steel and other heavy industries. Steel industries incorporate dynamic loads like furnaces and rolling mills; conventional compensation needs to meet performance requirements. The company’s solution tackles high harmonics caused by non-linear loads and low power factors due to dynamic loads. Here is a case study of a customised solution implemented by InPhase for one of the leading steel manufacturers in India.

Major Loads:

• Cold Rolling Mill (Main Stand) – 3 nos.
• Cold Rolling Mill (ETR/DTR) – 3 nos.
• Cold Rolling Mill (Aux) – 3 nos.
• Continuous Galvanising line (CGL) – 2 nos.

Existing Conventional Compensators

• 3200 KVAR, 11kV HT Fixed Filter Bank
• 3800 KVAR, 11kV HT Fixed Filter Bank
• 5250 KVAR, 11kV HT Fixed Filter Bank
• 1900 KVAR, 11kV HT Fixed Filter Bank

Power Quality Issues:

The plant was operating at an average monthly PF of 0.93.

Even with the manual operation of the HT capacitor banks, it was not feasible to maintain a PF of more than 0.93 due to the highly dynamic nature of the loads in the steel industry.

High voltage notches are present in the system due to the rolling mill.

Commercial Implications:
Since the inception of the kVAH billing methodology in Maharashtra in April 2020, the plant has been running at a low PF of 0.93. Due to this, they were paying higher electricity bills of 30 – 40 lakh rupees every month.

Implemented Solution:
Active Dynamic Reactive Power compensator
Incomer-1: +/-4700kVAR ASTRA
Incomer-2: +/- 2700kVAR ASTRA
The ASTRA panels are designed to improve PF at the metering point, taking direct CT feedback from 132kV Incomer.

Performance Achieved:

Note: Adding an Active Compensator to the existing HT/LT Passive PF correction system can provide additional fine-tuning capabilities. The Active Compensator can continuously monitor the power factor and dynamically inject or absorb reactive power to maintain a desired power factor.

Technical & Commercial Benefits Achieved:

• Manual operation of HT Capacitor bank is stopped. The Active system will compensate for all dynamic requirements without any manual intervention.
• Customer is reducing the electricity bill by 40 lakhs every month since the installation of the ASTRA panels.

Special Features of ASTRA:

• Dynamic lagging and Leading reactive power compensation for full rated capacity.
• Harmonic mitigation.
• Efficiency – 98 percent.
• IGBT-based 3-Level Topology.
• DC film type Capacitors for Long life.
• L-C-L input filter design for ripple-free operation.
• Can operate based on direct HT CT Feedback.
• Easy upgradation in future by adding additional modules in parallel.