304SE Energy Systems Assignment Questions | PSB

304SE Question 1

A boiler generates 5000 kg of steam per hour. The specific enthalpy of the steam is 3600 kJ/kg, and the specific enthalpy of the water supplied to the boiler is 300 kJ/kg. The calorific value of the fuel oil is 45 MJ/Kg.

• Determine the amount of fuel oil supplied, assuming the heat process is 70 % efficient. (10 marks)
• If the steam raised in the above example is supplied to the steam turbine and the enthalpy of the water-steam mixture at the turbine outlet is 2700 kJ/kg. Determine the power output from the steam turbine. Assume the losses in the turbine amount to 12 %. (10 marks)
• For 5000 kg/hr of fuel used, estimate the carbon emission per year for each fuel, and Comment on the results obtained

Fuel A: Diesel with carbon emission factor 3.15 kg CO2/kg

Fuel B: Coal with carbon emission factor 2.4 kg CO2/kg

Note: Total carbon emission per year =Fuel consumption per year ×Carbon emission factor (10 marks)

• What are the benefits of replacing the fossil fuel mentioned in Q1.c with a renewable source? (10 marks)

[Total marks 40]

304SE Question 2

A Three-bus power system is shown in Figure Q2.

Figure Q2

The data for the buses are given in Table Q2 A to E below.

Table Q2.A: Bus Data

Table Q2.B: Generator Data

Table Q2.C: Line Data

Table Q2.D: Load Data

Table Q2.E: Reactive Power Compensator

• From the Network Details, we find that Lines 1,2 and 3 are using the same type of cable with R= 0.005 Ω /km and X= 0.001 Ω /km. Observe table Q2. C, try to theoretically find the Rpu, Xpu and Bpu. Comment on the PU values obtained.
  (5 marks)
• Follow the instructions given in Table Q2 B to D to construct the network using “Power World” software.
• NOTE: System base no changes applied, default base MVA will be 100 MVA.
  All the field values, such as voltage and phase angle at every bus, and real and reactive power at both ends of every line, must be included in the circuit. The created network (before simulation) must be included in your report. (15 marks)
• From the Tools menu, choose Solve and perform the Load Flow analysis. The simulated diagram with all the field values clearly shown must be included in your report. So to avoid black-out once the loads are added, start the load at 100MW and 100MVAr each slowly increase the load to the set value. Why do you think the variable loads are better handled by a generator than a sudden huge load? (10 marks)
• Observe the transmission line loss for lines 1, 2 and 3, respectively, without a shunt capacitor, including simulation observation of V, P and Q loss on lines and provide theoretical analysis for voltage regulation of lines 1,2 and 3. Suggest which line might need to be modified to improve the overall efficiency of the system.
  (10 marks)
• Repeat steps C and D with the modified network by adding a shunt capacitor, and include information on the bus voltage and real and reactive power loss analysis for the modified network. Compare these results with those obtained in steps C and D
  (20 marks)

 [Total marks 60]