Research On Service Restoration Method For Active Distribution Network

The problem of the active distribution network (ADN) fault recovery reconstitution is multi-objective, constraint, discontinuous, multi-period and nonlinear, which is a complex optimization combination problem. The scale of the problem increases with the expansion of network size, and the goal of recovering the failure often contradicts, which is known as a NP problem in math. When the Distributed Generation (DG) is connected to the electricity grid, the traditional passive is changed into ADN. In order to promote the rapid development of ADN, and to ensure the reliability, economy and security of the network, it’s necessary to deeply analyze the new problems brought by DG access to ADN fault recovery reconstruction, and the methods to reconstruct ADN fault recovery.In order to quickly and effectively recover the electricity use in non-fault power-off regions, the ADN fault-recovery mathematical model with multi-objective, multi-constraint characteristics is built. Based on DG, ADN can be divided into two types:one is that all DG is not off-grid from the electricity grid after fault happening; the other is that some DG can be off-grid and can run independently. Considering all the factors, the problem of ADN fault-recovery reconstruction is analyzed.After building the fault-recovery method for ADN based on DG classification, first, power flow calculation method-newton-raphson method-is used to calculate the flow of distribution network, and the switches, which can’t satisfy the constraints under the normal running of the ADN, are deleted. Second, the adaptive genetic algorithm is used to optimally calculate the best switch assembly needed by the electricity recovery in power-off regions, based on the three built objective functions- the maximum number of electricity load power supply recovery; the minimum switch operand; the minimum power network loss- and the constraint conditions such as branch of power grid capacity, node voltage, current, power distribution network cannot appear ring needed for the normal operation of power grid.The whole research process is carried out by using MATLAB software to calculate the algorithm and power flow. Finally, the reliability and effectiveness of the model is verified, analyzing IEEE33 node case.