ELEC7310-无代写
时间:2023-05-07
Mid-Semester Examination, Semester – 1, 2019
ELEC7310: Electricity Market Operations and Security
School of ITEE, The University of Queensland
Maximum marks = 30
PART 1:
Question 1.1: Define deregulation in electricity markets. State any two factors that motivated
deregulation. (2 marks)
Question 1.2: A fully deregulated electricity market includes a wholesale market and a retail market. Who
are the buyers and sellers in each market? (2 marks)
Question 1.3: The Australian National Electricity Market has three main regulatory bodies whose
abbreviated titles are AEMC, AER and AEMO. Give the full names of each of these organisations and briefly
state their key roles in National Electricity Market. (2 marks)
Question 1.4: Which of the following correctly describes the market design of the Australian National
Electricity Market – select True or False: (2 marks)
a) Dispatch intervals are for a 5-minute duration.
b) The Spot market is compulsory, however, there is also a voluntary derivative market. The spot
market is used for balancing shortfalls not covered by bilateral contracts.
PART 2:
Question 2.1: The operator of a centralized market for electricity has received the bids shown in the table
below for the supply of electrical energy during a given period.
Company/Generator Amount (MWh) Price ($/MWh)
G1-1 100 12.5
G1-2 100 14.0
G1-3 50 18.0
G2-1 200 10.5
G2-2 200 13.0
G2-3 100 15.0
G3-1 50 13.5
G3-2 50 14.5
G3-3 50 15.5
(a) Build the supply curve. (3 marks)
(b) Assume that this market operates unilaterally, that is, the demand does not bid and is represented
by a forecast. Calculate the market price, the quantity produced by each company, and the
revenue of each company if the load is 300 MW. (4 marks)
Question 2.2: Quadratic cost characteristic curve (F) of a gas fired generating unit is given by:
F(Pgi) = 0.0025Pgi2 + 9.3Pgi + 120 $/h (1)
(a) Using (1), derive the expressions for average and marginal costs for the generating unit.
(4 marks)
(b) For this generating unit, at what generation level is the average cost the same as the marginal
cost? (1 marks)
Part 3:
Question 3.1: Short answer type questions
(a) What is the fundamental requirement to ensure that frequency of a power system remains
constant? (1.5 mark)
(b) Susceptibility of power systems to sudden frequency deviations (from 50Hz or 60Hz) is governed
by the size of power systems. Is this statement true or false? Briefly explain your choice.
(1.5 mark)
(c) State a preventive ancillary service and a corrective ancillary service for balancing the imbalances
between generation and loads. (2 marks)
Question 3.2:
(a) Consider a 2-bus power system as shown in Figure 1. (2 marks)
a. List the three main possible modes of destabilization that a system operator has to address through
preventive network ancillary services actions.
b. Which one of these modes places the most severe restriction on maximum power transfer from A
to B.
Figure 1
(b) The purpose of this question is to discuss the role of reactive power support ancillary services that are
needed for voltage regulation. In Figure 1, let the power flows from generator A to the load at bus B.
Figure 2 shows variations in reactive power injection/absorption at bus B to maintain voltage at bus B
(VB) within permissible limits (0.95 . ≤ ≤ 1.05 . ). To maintain VB within permissible limits,
reactive power must be absorbed at low real power transfer levels (below 100 MW) and reactive
power must be injected at high real power transfer levels (above 145 MW). Explain why this is the case
(with reference to Figures 1 and 2 and considering the effect of the transmission line connecting A and
B. (3 marks)
Figure 2. Reactive power injection at bus B: The voltage (solid line), the reactive power injection needed to regulate voltage
within limits (dash line), plotted against active power transfer from bus A to bus B in x-axis.