A novel forward-backward zero bus power flow method for the placement of renewable DGs in distribution network

The zero bus power flow (ZBPF) method is a recent development in the field of operation of active distribution network with renewable distributed generations (RNDGs), where a certain percentage of the total real and reactive power load demand is imported from the main grid, and the rest of the load demand is supplied by the DGs. DG connected to the zero bus ensures the pre-specified energy exchange with the upstream grid and the distribution network. However, to adopt the idea the standard load flow should be changed due to the absence of a slack bus. In literature, Newton-Raphson load flow (NRLF) is available; however, NRLF will not be converged for the distribution networks where the ratio of resistance to inductance $\left(\frac{R}{X}\right)$ is very high. To sort out this issue, a modified forward-backward based load flow is developed in this paper to consider the effect of zero bus and pre-specified energy exchange with the upstream grid. To determine the location of zero bus, locations and the sizes of DGs, and shunt capacitor, a multi-objective optimization problem (MOOP) is proposed here. The fuzzy maxmin principle (FMMP) based mixed discrete particle swarm optimization (MDPSO) is applied for the optimal placement of the RNDGs, and shunt capacitor in 33 bus DN.