| Author | Samarakoon, H. M. D. R. H. |
| Call Number | AIT Diss. no. ET-99-4 |
| Subject(s) | Electric power transmission
Electric utilities--Costs
|
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of
Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | A generation expansion planning model considering transmission system cost and a
transmission expansion planning model considering power plant location selection are
developed in this study in order to consider the interactions between generation plant locations
and transmission network development. The treatment of generation and transmission
expansion planning in two separate models facilitates more technical considerations including
probabilistic production cost simulation, transmission network security constraints and load
flow analyses. These two ·models are used iteratively to improve the solution till convergence
is achieved.
The generation expansion planning problem is formulated as a dynamic programming model
that has three sub-models for calculating (i) generating capacity cost, (ii) electricity production
cost and (iii) transmission cost for each state (i.e., a combination of generation plants) of each
stage (i.e., a period of the planning horizon). Such a model formulation helps to consider the
variations of transmission cost with regards to location, size and time of commissioning of
power plants, while retaining more sophisticated technical features in the existing generation .
planning models (e.g., probabilistic production cost simulation).
The transmission expansion planning model considering power plant location selection is a
single period mixed integer linear programming model. The non-linearity of the DC load flow
equations of the model for)llulation is avoided by using a new state enumeration technique that
reduces the size of the formulation. Line outage distribution factors (LODFs) are used in order
to identify the critical contingencies of the network and to formulate security constraints of the
model. Such approci.ch reduces the problem size considerably.
The proposed planning approaches for generation and transmission are applied in the Sri
Lan.lean power system in order to compare planning and cost implications of the approaches
with that of the sequential generation and transmission planning approach (i.e., without
consideration of interactions between generation and transmission). Results of the case study
show that the power plants capacity mix and plant locations under the proposed planning
approaches are quite different from that under the sequential planning approach. These
proposed approaches are resulted in a net reduction in the total cost of the power system with
considerable reduction in costs of transmission, but a higher cost of generation.
The transmission planning solutions obtained in these proposed approaches are further·
improved with the consideration of reactive power flows in the network. A separate
transmission planning model is developed for this purpose. Sensitivity factors (COSFs) of the
voltage magnitude and phase angle for a circuit outage are derived using decoupled load flow
in order to formulate security constraints, which do not incorporate any additional variable. A
method for identifying critical contingencies is developed using COSFs. Such approach helps
to reduce number of constraints considerably.
111 '·
The study further examines (i) the importance of voltage stability aspect in transmission
planning; (ii) the voltage stability implication of the proposed planning approach and (iii) the
planning implications of the consideration of power cables in urban areas as a technical option
in order to reduce long term health hazards in power transmission. It shows that the system
voltage stability is quite improved under the proposed planning approach. However, it shows
the criticality of the system in terms of voltage stability in the cases studied. The consideration
of power cables in urban areas results in a change of generation schedule as well as a slight
increase in the total cost of generation and transmission of the system.
The study also analyzes the implications of the proposed generation and transmission planning
approach for transmission pricing. A transmission pricing approach is developed for this
purpose. The proposed pricing approach stipulates transmission price to have variable and
fixed charge components. The variable charge is based on the marginal variable cost. The
fixed charge at a node is determined on the basis on marginal capacity cost at the node and
taking into account for the expected return on h·ansmission capital. It is charged according to
the operating capacity and the location of individual suppliers and independent of their
operating patterns. The node based fixed charge approach is then extended to a long term
contract structure which makes contracts between transmission utility and the power suppliers
to access the network from a specified location up to a specified capacity. The proposed
contracts allow the suppliers to access any consumer in the network without making any
restriction on their transmission paths. The case study of the Sri Lankan power system using
the proposed transmission pricing approach shows that the revenues from variable and fixed
charges and expected return on capital investments in transmission significantly vary with the
system expansion planning criteria. |
| Year | 1999 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Shrestha, Ram M.; |
| Examination Committee(s) | Fujiwara, Okitsugu ;Thukaram, D. ;Surapong Chirarattananon ;Rahman, Saifur; |
| Scholarship Donor(s) | The Government of Japan; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1999 |
