Transmission Expansion Planning in Deregulated Power ... - tuprints

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Transmission Expansion Planning in Deregulated Power ... - tuprints

2 Transmission Expansion Planning Approaches 5

2.1.1 Non-deterministic Transmission Expansion Planning Approaches

Uncertainties can be classified in two categories:

• Random, and

• non-random uncertainties.

Random uncertainties are deviation of those parameters which are repeatable and have a

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

observations. Uncertainty in load is in this category. Non-random uncertainties are evolution

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

past observations. Uncertainty in generation expansion is in this category. Besides the

uncertainties, there are imprecision and vague data in expansion planning. Imprecision and

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

criteria in multi objective planning falls in this category.

Non-deterministic approaches which have been used for transmission expansion planning are:

• probabilistic load flow,

• probabilistic based reliability criteria,

• scenario technique,

• decision analysis, and

• fuzzy decision making.

Probabilistic load flow and probabilistic based reliability criteria approches take into account

random uncertainties. Scenario technique considers the non-random uncertainties. Decision

analysis is a proper method for dynamic programming. Fuzzy decision making considers

imprecision and vague data.

2.1.1.1 Probabilistic Load Flow

Probabilistic load flow is used for network analyzing and expansion planning of regulated

power systems. Probabilistic load flow is similar to ordinary load flow, except it gets the

probability density functions (PDFs) of loads as input and computes the PDFs of output

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

and combination of them. PDFs of loads can be estimated based on load prediction and

uncertainty analysis [8]. To reduce the computations, power flow equations are linearized

around the expected value region and then convolution technique is used for computing the

PDFs of outputs. The algorithm of transmission expansion planning using probabilistic load

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