Transmission Expansion Planning in Deregulated Power ... - tuprints

2 **Transmission** **Expansion** **Plann ing** Approaches 5

2.1.1 Non-determ**in**istic **Transmission** **Expansion** **Plann ing** Approaches

Uncerta**in**ties can be classified **in** two categories:

• Random, and

• non-random uncerta**in**ties.

Random uncerta**in**ties are deviation of those parameters which are repeatable and have a

known probability distribution. Hence, their statistics can be derived from the past

observations. Uncerta**in**ty **in** load is **in** this category. Non-random uncerta**in**ties are evolution

of parameters which are not repeatable and hence their statistics cannot be derived from the

past observations. Uncerta**in**ty **in** generation expansion is **in** this category. Besides the

uncerta**in**ties, there are imprecision and vague data **in** expansion plann**in**g. Imprecision and

vague data are the data which can not be clearly expressed. Importance degree of different

criteria **in** multi objective plann**in**g falls **in** this category.

Non-determ**in**istic approaches which have been used for transmission expansion plann**in**g are:

• probabilistic load flow,

• probabilistic based reliability criteria,

• scenario technique,

• decision analysis, and

• fuzzy decision mak**in**g.

Probabilistic load flow and probabilistic based reliability criteria approches take **in**to account

random uncerta**in**ties. Scenario technique considers the non-random uncerta**in**ties. Decision

analysis is a proper method for dynamic programm**in**g. Fuzzy decision mak**in**g considers

imprecision and vague data.

2.1.1.1 Probabilistic Load Flow

Probabilistic load flow is used for network analyz**in**g and expansion plann**in**g of regulated

power systems. Probabilistic load flow is similar to ord**in**ary load flow, except it gets the

probability density functions (PDFs) of loads as **in**put and computes the PDFs of output

variables [4]-[7]. This can be accomplished by Monte Carlo simulation, analytical methods

and comb**in**ation of them. PDFs of loads can be estimated based on load prediction and

uncerta**in**ty analysis [8]. To reduce the computations, power flow equations are l**in**earized

around the expected value region and then convolution technique is used for comput**in**g the

PDFs of outputs. The algorithm of transmission expansion plann**in**g us**in**g probabilistic load