Multi-objective Dynamic Reconfiguration for Urban Distribution Network Considering Multi-level Switching Modes

The increasing integration of photovoltaic generators(PVGs) and the uneven economic development in different regions may cause the unbalanced spatial-temporal distribution of load demands in an urban distribution network(UDN). This may lead to undesired consequences, including PVG curtailment, load shedding, and equipment inefficiency, etc. Global dynamic reconfiguration provides a promising method to solve those challenges. However, the power flow transfer capabilities for different kinds of switches are diverse, and the willingness of distribution system operators(DSOs) to select them is also different. In this paper, we formulate a multi-objective dynamic reconfiguration optimization model suitable for multi-level switching modes to minimize the operation cost, load imbalance, and the PVG curtailment. The multi-level switching includes feeder-level switching, transformer-level switching, and substation-level switching. A novel load balancing index is devised to quantify the global load balancing degree at different levels. Then, a stochastic programming model based on selected scenarios is established to address the uncertainties of PVGs and loads. Afterward, the fuzzy c-means(FCMs) clustering is applied to divide the time periods of reconfiguration. Furthermore, the modified binary particle swarm optimization(BPSO)and Cplex solver are combined to solve the proposed mixed-integer second-order cone programming(MISOCP) model. Numerical results based on the 148-node and 297-node systems are obtained to validate the effectiveness of the proposed method.

Optimal Feeder Routing in Urban Distribution Networks Planning with Layout Constraints and Losses

We address the problem of optimally re-routing the feeders of urban distribution network in Milano,Italy,which presents some peculiarities and significant design challenges.Milano has two separate medium-voltage(MV)distribution networks,previously operated by two different utilities,which grew up independently and incoordinately.This results in a system layout which is inefficient,redundant,and difficult to manage due to different operating procedures.The current utility UNARETI,which is in charge of the overall distribution system,aims at optimally integrating the two MV distribution networks and moving to a new specific layout that offers advantages from the perspectives of reliability and flexibility.We present a mixed-integer programming(MIP)approach for the design of a new network configuration satisfying the so-called 2-step ladder layout required by the planner.The model accounts for the main electrical constraints such as power flow equations,thermal limits of high-voltage(HV)/MV substation transformers,line thermal limits,and the maximum number of customers per feeder.Real power losses are taken into account via a quadratic formulation and a piecewise linear approximation.Computational tests on a small-scale system and on a part of the Milano distribution network are reported.