This paper proposes two approaches for optimal scheduling of unit commitment (UC) considering
reserve generating for competitive market. The particle swarm optimization (PSO) technique is
used to find out the solution of both optimal UC and power generation problems, simultaneously.
The two proposed approaches depend on various sigmoid functions to obtain the binary values
PSO. The first approach takes the fuzzification of generation costs as a sigmoid function; while the
second approach takes the fuzzification of power generation as sigmoid function. A proposed
objective function is presented dependent on the exponential form which leads to fast convergence
of PSO solution. This objective aims to minimize the generation costs as well as maximize their
own profit while all load demand and generation reserve are satisfied. Hence, the generations
companies (GENCO) schedule their generators with objective maximize their own profit with
regard for system social benefit. This means that, this objective helps GENCO to make a decision,
how much power and reserve should be sold in markets and how to schedule generators in order to
receive the maximum the profit. Different comparisons are carried out using various standard test
systems to show the capability of the two proposed sigmoid approaches and the proposed objective
function compared with other techniques