Research on distribution system planning theoryunder the trend of load-supply integration

In this paper, a new distribution system planning theory under the trend of load-supply integration is explored. First, this paper analyzes the development trends and characteristics of future distribution system, and points out that the integration of load-supply will be the most important feature of future distribution system. The feature blurred the boundaries between the load and the power supply, makes energy complementary strengths fuller, power system operation more flexible, electricity balance more timely. The feature also hasa major impact on distribution system planning. Boundary conditions of planning become less clear and more uncertainty, optional schemes varied. This paper analyzes the basic theory of traditional distribution network planning methodology and inadaptability in the situation of integration of load-supply. Further, this paper proposes a new construction idea of theoretical system of distribution system planning under the situation of load-supply integration from the five areas of objective, requirements, core, key points and process. Distribution system planning objective will change from single, short-term to multidimensional, long-term. The requirements of long-term system reliability, economy and asset life-cycle management will be higher. Planning accuracy requirements will further increase and be closer to the operational requirements. Accurate planning will establish load models of the load-supply integration, carry out characterization analysis and distribution network system calculation to search limit states and weak links of system operation. Core of distribution system planning is using divided-period probabilistic production simulation of power system based on synchronization of load and supply to replace the traditional method of power balance. Simulation results contain system operation reliability analysis of different types of typical periods and operational state, and iterative optimization with all distributed power supply, micro-grid, active load of planning area and external power exchange. Overall operating cost index obtained from optimization analysis supply the basis for scheme comparison and selection. Planning key is to improve the network adaptability, to achieve the maximum range of plugging and playing of distributed power, energy storing device and various control units. Planning process shall include repeated iterative optimization of source, load, transmission system and distribution system.