Zone-Based Voltage Optimization in Distribution Grids with DGs

The paper addresses the problem of optimizing the voltage profile in a radial distribution network by acting on the reactive powers provided by distributed generators. To limit the requirements for measurements and communication infrastructures, a decentralized approach is adopted to solve a voltage optimization problem. Firstly, a linear method for analyzing the steady-state operation of distribution grids is used to formulate a centralized voltage optimization problem of a network partitioned in voltage control zones. Then, overlapping variables are introduced and the lack of strict convexity of the objective function is handled by adopting the iterative method of multipliers. Finally, a fully decentralized problem is obtained by applying the alternating direction method of multipliers; it results in a quadratic programming problem to be solved in each area with a limited number of scalar variables to be exchanged. The effectiveness of the method is proved by performing numerical simulations on a 24-nodes LV distribution grid with DGs and comparing results with other methods.