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ΤHE SCIENTIFIC ENERGY SAVING PROJECT OF

SCIENTIFIC ENERGY MANAGEMENT DMCC (SEMAN DMCC)

IN AL-ASSEMAH STEEL BILLETS FACTORY IN JEDDAH, KSA,

OF RAJHI STEEL INDUSTRIES CO.

Α. AL-ASSEMAH STEEL BILLETS FACTORY OF RAJHI STEEL INDUSTRIES CO.

Al-Assemah Steel Billets Factory (Rajhi Steel in brief, pictures 1 - 4) is based in the city

of Jeddah – Saudi Arabia and it is one of the leading national companies in iron and

steel industry and one of the Middle East & North Africa’s largest steel manufacturers,

especially in rebar and commercial steel. Some Rajhi Steel products include:

Rebars/Reinforcement Steel

Plain wire rod

Rebar coils

Rectangular and Square Tube

Hot Rolled Steel Sheets

Cold Rolled Steel Sheets

Zincor /Electro-Galvanized Sheets

Checkered Sheets

Galvanized Steel Sheets

Ordinary and Insulated Corrugated Sheets

Black Pipes

Galvanized Pipes

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Picture 1: Part of the plant in Jeddah

Picture 2: Production Line

Picture 3: Production Line

Picture 4: Production Line

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The total installed electric power of Rajhi Steel comes up to 55 MW. The grid is in 60Hz

and there are more than 10 Transformers that supply loads to various voltage levels

(e.g. 6300V, 3300V, 480V, 380-400V). The average annual cost of electricity is

approximately 4.430.000 € in current prices.

Β. The scientific project of SEMAN DMCC

The scientific project for energy saving and current - voltage quality improvement has

been concluded by SEMAN DMCC at the end of July 2013.

In order to elaborate the scientific study for Rajhi Steel’s Electric Power Grid, the

engineers’ staff of SEMAN DMCC performed measurements and recordings (Pictures 5,

6, 7 & 10) – of all the required electrical values – in each individual load of the

installation (AC & DC motors, motors operating with Inverters, inductive furnaces, DC

Converters, Star- Delta switches etc. both in Low and Medium Voltage).

Picture 5: Laptops used for measurements and recordings

Measurements and recordings concerned the basic electric values (power, reactive

power, voltage, current, frequency) as well as current & voltage harmonics (up to the

35th class) and transient phenomena.

Inside the Electric Power Grid of Rajhi Steel Industry, transient phenomena occur not

only from the disturbances catering from Public Power Distribution Network, but also

from their own big electric loads that start and stop sharply during production days.

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Picture 6: Measurements have been performed also in the core of the electrical installation next to the loads

Moreover the engineers’ staff of SEMAN DMCC proceeded to the collection of all the

essential data that had to do with lengths and cross-sections of cables, number of

cables headed together in canals, nominal values of motors, power transformers and

many others also necessary for elaborating the scientific study for the energy saving

project.

Picture 7: Measurements with special power quality analyzers and laptops

Based on the above, the engineers of SEMAN DMCC were able to simulate the

behavior of Rajhi Steel’s Electric Power Grid and detect all the problems that were

causing bad quality of voltage and current, low electric loads and power transformers

efficiency, harmonic resonances and multiple other energy losses. The simulations

conducted are based on SEMAN DMCC’s know-how, which has been awarded by the

university of Cambridge and USA institutes. More particularly, models based on the

Finite Elements Method (FEM) in combination with load flow analysis were used to

complete all the required simulations (more information concerning SEMAN DMCC’s

simulation models can be found at http://www.seman.gr/F7FF7B13.en.aspx.

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The analysis of measurements and recordings showed that considerable harmonic

sources existed inside Rajhi Steel’s Electric Network, producing not only harmonic

currents (in some cases THD-I% reached 70% of the load),

Picture 8: Harmonic currents recordings in the electric network

but also considerable voltage harmonics.

Picture 9: Voltage harmonics recordings in the electric network

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Picture 10: Portable measurement devices

Moreover, a number of energy saving scenarios, for the specific Electrical Power Grid –

all based on the know-how of SEMAN DMCC – carried out by the use of simulations

and finally the scientific study concluded 38 customized interventions (please refer to

pictures 11, 12, 13, 14 & 15 for low voltage loads interventions and to pictures 16 & 17

for medium voltage loads interventions) that had been installed inside the Electric

Power Network of Rajhi Steel.

More specific:

12 interventions installed in LV 380V

20 interventions installed in LV 480V

2 interventions installed in LV 600V

4 interventions installed in MV 3,3kV.

The total installed power of the customized interventions for the voltage-current

quality improvement and energy saving project was 7,8MVA.

The target of the installed interventions is to minimize the current-voltage harmonics,

to improve the current-voltage quality of the electric installation of Rajhi Steel plant

and finally to achieve electrical energy saving. The Current – Voltage Quality

improvement will lead to energy saving due to the:

Maximization of the total efficiency of the Electrical Installation,

Improvement of motors’ efficiencies, due to:

the minimization of the counterclockwise electromagnetic torques

caused by harmonics and,

the reduction of voltage drops and the higher constant voltage to

the motors.

Improvement of power transformers’ efficiencies by the reduction of their

copper and iron losses,

Reduction of the following thermal losses:

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Thermal losses of supply.

Contiguity Effect Losses.

Skin Effect Losses.

Eddy Current Losses.

It should be mentioned that the design of each customized intervention for every

electrical load took into consideration not only the interactions with all the other

electrical loads of the network, but also the resonance frequencies of every electrical

power cable of the grid.

Picture 11: Customized SEMAN DMCC Energy Saving Intervention for Low Voltage (LV) load in Rajhi Steel plant

Picture 12: Customized Reactor of a SEMAN DMCC LV Energy Saving Intervention in Rajhi Steel plant

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Picture 13: Customized SEMAN DMCC Energy Saving Intervention for a rapidly variable Low Voltage (LV) load in Rajhi Steel plant

The customized interventions for voltage-current quality improvement and energy

saving are connected in parallel to the electric loads and lead to harmonics absorption

and their important reduction inside the electric installation of the factory.

Furthermore, resonance frequencies that could lead to dangerous tuning are being cut

off. PLC with special software design from Seman DMCC’s engineers, based on the

results of the scientific study, control the dynamic operation of each intervention

according to the fluctuations of every electric load and ensure the cutting of all

dangerous interactions between the loads.

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Picture 14: Customized SEMAN DMCC Energy Saving LV Harmonic Filter in Rajhi Steel plant

Picture 15: Details of a customized SEMAN DMCC energy saving intervention - Active LV Harmonic Filter in Rajhi Steel

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Picture 16: Medium Voltage (MV) customized SEMAN DMCC Energy Saving Intervention in Rajhi Steel.

Picture 17: Details of a MV customized SEMAN DMCC energy saving intervention in Rajhi Steel

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C. Results – Benefits

For the evaluation of the Power Quality Improvement and Energy Saving Project in

Rajhi Steel plant, measurements and recordings were taken place in two time periods

(July and October) with and without the interventions into operation. The

measurements and recordings were realized in presence of Rajhi Steel’s staff of

engineers.

Applying these measurements - recordings to the electricity invoices, by the use of a

specific algorithm – created in collaboration with Rajhi Steel’s Industry staff of

engineers & Rajhi Steel Managers, the results presented in Table 1 are concluded.

Table 1. Synoptic Results of the Power Quality Improvement and Energy Saving Project accomplished for the Rajhi Steel Industry

Value

Results

Guaranteed saving according to the contract (%) -10,15%

Saving achieved (%)

(according also to the attached Reference Letter by

Rajhi Steel Company Management) -15,74%

Guaranteed Pay Back Period of the project (years)

3,2

Real Pay Back Period of the project (years) 2,06

Annual Money Saving(€) 697.282,00 €

In addition, SEMAN DMCC’s scientific project inside the electrical installation of Rajhi

Steel plant in Jeddah, Saudi Arabia, had some extra benefits, confirmed also by the

recordings before and after the installation of the energy saving equipment and the

ascertainments of Rajhi Steel responsible Managers.

These extra benefits are the following:

1. Reduction of current & voltage harmonics up to 80%.

This significant harmonics reduction is easily notable by viewing the four Graphs

representing the comparison of the Currents and Voltage Harmonics before SEMAN

DMCC’s project in operation (Pictures 8 and 9) and after SEMAN DMCC’s project in

operation (Pictures 18 & 19)

2. Optimization of the voltage & current quality of the electrical power grid of the

factory.

3. Maximization of the efficiency ratio of the electric power grid, motors and power

transformers.

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4. Reduction of undesirable stopping of production lines because of the reduction of

sensitivity of load voltage supply to immersions of the voltage supplied by the

electricity provider’s Power Distribution Network.

5. Increase of the reserve and capacity charge of the electrical installation, which is a

positive factor for the future plant’s expansions.

6. Reduction of the maintenance cost concerning all the components of the electrical

installation, which according to the plant’s technical department led to an additional

reduction of the pay back period.

Based on all above, the Power Quality Improvement & Energy Saving Project of SEMAN

DMCC in Rajhi Steel plant was proven to be absolutely successful, as it is also

confirmed at Rajhi Steel’s Reference letter delivered to SEMAN DMCC.

(please refer to the attached file “Reference Letter by Rajhi Steel.pdf”)

Picture 18: Harmonic currents recordings in the electric network after Seman DMCC’s project

Picture 19: Voltage harmonics recordings in the electric network after Seman DMCC’s project