In reconstructed environments, generation planning and transmission planning are separated and problem is faced a lot of uncertainty in generation and load. Type, capacity, and location of power plants may change during the operational phase which indeed may increase the uncertainty of input data \cite{Zhao_2011}. DG units can be valued in two ways:
1- When the share and contribution of DG units be low in market, a unit of DG is usually modeled in the model of distribution network as a negative load and the distribution company constructs it when its cost is lower than buying electricity from market.
2- When DG influence level reaches to specific level, each DG can be considered as a standard power plant generation with technology \(j\) in bus \(i\) and its value is determined by Net Present Value (NPV) criterion which has been discussed in below section:
After calculating the knot price during the period of the lifetime of the power plant, financial circulation of the power plant \(j\) in year \(t\) is calculated as follows:
\(CF_i=(Z_i(t)-C_{VO\&M}-C_{fuel})\times f_c_a_p\times8760-C_(_F_O_\&_M_)\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \left(14\right)\)
In which \(C_{VO\&M}\) , \(C_{FO\&M}\) and \(C_{fuel}\) are variable cost of repairs and maintenance, constant cost of repairs and maintenance and the fuel cost of technology \(j\) . The term \(f_{cap}\) shows the capacity coefficient of the power plant. Then, NPV is calculated thorough the below equation:
\[NPV_{i,j}=C_{Cap}+\sum_{i=1}^T(CF_t\times e^{-rt})\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \left(15\right)\]
While is the interest rate without risk and is the cost of constructing the power plant . However, it is possible to consider the government encouraging schemes in promoting of renewable resource in investments. Thus, according to equation (15), the current pure value of each technology in each base can be calculated. Then, candidate cases for generation are cases with higher NPV in electricity market.
Simulation Results