Deregulation of the power industry and liberalization of electricity market with all accompanying processes have changed the status and the requirements for power distribution business. They have also substantially changed the conditions for planning development and construction of a power distribution system. Current conventional criteria and methodology of planning should be completed with the influencing parameters such as safety and reliability criteria, electricity quality criteria, impact of distributed generation, limited funds impact, unavailability of planning data, and the property management criteria. The structure and characteristics of an integral planning process have been defined and the planning criteria have been grouped as follows: - Deterministic criteria – voltage, frequency, and grid element load, - Probabilistic criteria – safety and reliability, and - Other criteria – quality of electricity and other influencing parameters The impact of distributed generation was elaborated as a substantial planning uncertainty. The safety and reliability of distribution grids were elaborated as the planning process parameters including the technical solutions for higher reliability. The criteria and the requirements for electricity quality in the planning process were defined and the technical solutions for quality improvement were evaluated. The electricity quality status and distribution of some quality parameters on a real power grid were analyzed. By statistical processing of the results of monitoring the indicators, dependence and impact of indicators of the distribution grid reliability on several parameters on a real power grid were analyzed. A statistical approach was applied to identify correlation dependences of reliability indicators on financing investment relations between cable and overhead grid, topology and mesh structure of the grid (redundant power supply), and technological and organizational level of the grid operation control. A model for defining the indicators of grid reliability in future depending on financial investment in the grid and a general model for defining the funds required for financial investment in the power grid to achieve target indicators of grid reliability have been developed.