sbe2112 electrical systems assignment 2 you are working in the process
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SBE2112 Electrical Systems
Assignment 2
You are working in the process industry as an IWSP student. Your industry supervisor has assigned you
the task of identifying opportunities for improving energy efficiency, with the ultimate objective of
reducing the monthly electricity bill.
The process plant is highly automated and operates on 24-hour basis. It takes power supply from the grid
at 22 kV and hence qualifies for High Tension tariffs as shown in Figure 1.
Having analyzed the past monthly electricity bills and observed the power trending of the plant SCADA
(supervisory control and data acquisition) system, you found that the process plant effectively takes a
constant power of 5 MW at a lagging power factor of 0.83. The 3 phases of the power supply system are
balanced.
You were excited with the opportunity to start with the “low hanging fruit” of improving the power factor
and hence reducing or avoiding the reactive power charges in the monthly electricity bills.
You proceeded with calculating the reactive power taken by the plant and thereby determined the size
(rating in KVAR) of the power factor correction capacitors required to improve the power factor to unity.
Your vendor (contractor) has quoted you the cost of implementing power factor correction unit at $150
per KVAR, including all installation cost.
You discussed your preliminary findings with your industry supervisor. He instructed you to prepare a
report for submission to the plant operation manager who is a chemical engineer with limited knowledge
in electrical engineering.
Your Report
Your report should include, but not limited to, the following points:
•
An explanation of the basis of reactive power charges in the electricity tariffs;
The opportunity to reduce the reactive power charges in your process plant through power factor
improvement;
Your proposed approach of using capacitors for reactive power compensation (power factor
improvement);
• Your calculation in sizing the required capacitive KVAR;
• The project costing for implementing the power factor improvement;
The estimated pay-back period;
• Your recommendations, supported by reasons, for installing the power factor correction unit.
Submit your assignment through Dropbox in XSite.
The deadline for submission of your report is 22 March 2024, 2359hours. ELECTRICITY TARIFFS FROM 1 OCTOBER 2022
Existing Tariff
(without GST]
New Tariff
(without GST)
New Tariff
(with 7% GST)
LOW TENSION SUPPLIES, DOMESTIC
30.17
29.74
31.82
All units, c/kWh
LOW TENSION SUPPLIES, NON-DOMESTIC
30.17
29.74
31.82
All units, c/kWh
HIGH TENSION SMALL (HTS) SUPPLIES
Contracted Capacity Charge
11.95
11.95
12.79
S/kW/month
Uncontracted Capacity Charge
17.93
17.93
19.19
$/chargeable kW/month
kWh charge, c/kWh
Peak period (7.00am to 11.00pm]
27.81
27.17
29.07
Off-peak period (11.00pm to 7.00am)
16.49
16.69
17.86
Reactive power Charge
0.59
0.59
0.63
c/chargeable kVARh
HIGH TENSION LARGE (HTL) SUPPLIES
Contracted Capacity Charge
11.95
11.95
12.79
S/kW/month
Uncontracted Capacity Charge
17.93
17.93
19.19
$/chargeable kW/month
kWh charge, c/kWh
Peak period (7.00am to 11.00pm]
27.59
26.95
28.84
Off-peak period (11.00pm to 7.00am)
16.48
16.68
17.85
Reactive power Charge
0.59
0.59
0.63
c/chargeable kVARh
EXTRA HIGH TENSION (EHT) SUPPLIES
Contracted Capacity Charge
10.09
10.09
10.80
S/kW/month
Uncontracted Capacity Charge
15.14
15.14
16.20
$/chargeable kW/month
kWh charge, c/kWh
Peak period (7.00am to 11.00pm]
26.57
25.96
27.78
Off-peak period (11.00pm to 7.00am)
16.35
16.56
17.72
Reactive power Charge
0.48
0.48
0.51
c/chargeable kVARh
Figure 1 - Electricity Tariffs