In this paper a novel approach for optimal location, sizing and determining the service areas of HV/MV substations in a long-range planning period using pseudo dynamic methodology is presented. Costs of equipment, areas, cables in MV side and power loss are considered in cost function. Uncertainty in loads is modeled using LR fuzzy numbers in load points. For optimization procedure, genetic algorithm (GA) with a new coding is used. Load points splitting in each area between substations and infeasibility solutions are considered in search procedure. Based on this, software was developed and integrated into an optimization tool for substation allocation. The software was applied in many cases with satisfactory results.

Storage of natural gas in liquid hydrocarbons is one procedure for automotive natural gas usage that reduces the requirements of high-pressure or cryogenic storage needed in other common techniques such as CNG and LNG. Model solutions of Methane in 52 solvents and Tehran Refinery productions were simulated using various equations of state to determine the pressures necessary to maintain a liquid phase at ambient temperature. The calculation results show that the storage pressure can be reduced to 15 MPa, and due to the storage condition in the liquid phase, the energy density is increased up to almost 40% of the energy density of gasoline. With this technology, the low storage density of CNG and the very low storage temperature of LNG are both overcome, thus dramatically improving the technical feasibility of large-scale commercialization of natural gas powered vehicles.

Insufficient electrical endurance of equipment and insulation failure against overvoltage are one of the most effective reasons for the failure of the power lines. Lightening, switching, or other disruptive parameters can cause line outage or distribution substation failure. There are different devices used to improve the safety, reliability, and power quality of the system. Surge arresters are one of the insulation protection subsystems used against surge and switching overvoltages. In this paper, the effects of surge arrester performance have been investigated on the insulation system of distribution substation. The study has been done under normal and also transient conditions due to lightning overvoltage. The effects of failure rate, production quality, voltage stress, temperature and surge arrester permutation have been evaluated on surge arrester performances. The influence of surge arrester aging, as the most influential factor on the surge arrester performance, has been investigated as one of the factors involved in the present study. Obtained results have verified the great impact of surge arrester aging effect on the reliability of protection system.

In recent years, significant research efforts have been devoted to the optimal planning of power systems. Substation Expansion Planning (SEP) as a sub-system of power system planning consists of finding the most economical solution with the optimal location and size of future substations and/or feeders to meet the future demand. The large number of design variables, and combination of discrete and continuous variables makes the substation expansion planning a very challenging problem. So far, various methods have been presented to solve such a complicated problem. Since the Bacterial Foraging Optimization Algorithm (BFOA) has been proper results in studies of power systems, and has not been applied to SEP problem yet, this paper develops a new BFO-based method to solve the SEP problem. The technique discussed in this paper uses BFOA to simultaneously optimize the sizes and locations of both the existing and new installed substation and feeders by considering reliability constraints. To clarify the capabilities of the presented method a typical network is considered and the results of applying GA and BFOA on the network are compared. The simulation results demonstrate that the BFOA has the potential to find more optimal results than the other algorithm under the same conditions. Also, the fast convergence, consideration of real-world networks limitations as problem constraints and simplicity in applying to large scale networks are the main features of the proposed method.

Abstract: The connection points between MV and LV distribution networks are MV substations. Optimal sitting, sizing and timing of MV substation placement is the major planning problem in MV-LV distribution system planning projects. In this paper the optimal MV substation placement problem is solved using Imperialist Competitive Algorithm (ICA) as a new developed heuristic optimization algorithm. This proposed procedure is determined the optimal location, capacity and installation time of MV substation, regarding the operating and optimization constraints. A multistage and pseudo dynamic expansion planning methodology is applied to consider uncertainties in network parameters such as forecasted load, asset management and geographical constraints. In order to evaluate the efficiency of the proposed method obtained by ICA, a sensitivity analysis for the effect of ICA parameters on obtained results is applied. A graphical representation of results is used to illustrate the efficiency and capability of the procedure both from the planning and graphical aspects. The proposed method has been tested on a real size distribution network.