# Transmission Expansion Planning in Deregulated Power ... - tuprints Transmission Expansion Planning in Deregulated Power ... - tuprints

4 Market Based Criteria 38

k µ lmp is equal to:

1

Nb

k

k

µ lmp = ∑ µ lmp

(4.9)

N i

b i=

1

k

Standard deviation of mean of LMP in the presence of plan k ( σ ) indicates how spread

µ

k

out the mean of LMP of different buses ( µ for i=1, 2,…, Nb) are from the average LMP

lmp

of the network ( µ ). As the standard deviation of mean of LMP decreases, differences

k

lmp

among the mean of LMP of different buses decrease and the price profile become flatter.

Flatter price profile indicates less price discrimination. According to (4.2) as flatness of price

profile increases, congestion cost decreases. Therefore, as the standard deviation of mean of

LMP decreases, both transmission constraints and price discrimination decrease and hence

competition is encouraged. In the same way as the standard deviation of mean of LMP

increases, competition is discouraged. Therefore, standard deviation of mean of LMP is a

proper criterion for measuring the competitiveness degree of electric markets.

Since the budget of transmission expansion is limited, it is logical to provide a competitive

field for more participants or for more power with a given budget. Hence, weighted standard

deviation of mean of LMP is proposed for ranking the transmission plans:

σ µ

with:

k

lmp ,

=

w

k

lmp w , µ

1

Nb

∑ Nb −1

i=

1

w

µ

µ

k k k

i ( lmp −

i

lmp

)

2

i

lmp

(4.10)

σ weighted standard deviation of mean of LMP with the weight w in the

presence of plan k in \$/MWhr

k

w i weight of bus i after adding plan k

Generation power, load, and sum of generation power and load are suggested to weight each

bus.

4.2.2.2 Weighting with Mean of Generation Power

The mean of generation power at bus i after adding plan k in the peak load of planning

horizon is given by:

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