Hierarchical and Distributed Voltage Management in Smart Grid with Distribution Generator Participation

The primary purpose of a distribution system is to meet the damands optimally as well as to maintain voltage within a specified range. Since renewable energy resources such as wind and solar energy have intermittent nature, they cause significant fluctuations in distribution system voltages. In conventional methods, tap changer transformers, voltage regulators and capacitor banks are used to control the voltage of distribution network, but these equipments are not proper to track rapid changes. The proposed method in this paper which is based on distributed generations with smart inverters, presents a distributed and hierarchical management approach to maintain the bus voltages within an allowable range. At first, the distribution system is devided to multiple areas and then voltage profile is managed in an optimal way by determining reactive power set point of generators for each area in two levels: real-time primary level and coordinated secondary level. The results on 34-bus test feeder under different load level show that the proposed voltage management scheme has high accuracy and reasonable computation time which makes it efficient approach for smart distribution grid with renewable resources.