Multiperiod Optimum Power Flow for Active Distribution Networks With Provisioning of Ancillary Services

Thais M. Blasi,Fabricio H. Tabarro,Alexandre R. Aoki,Thelma S. P. Fernandes

doi:10.1109/access.2021.3101419

Abstract

Distribution networks are suffering a transformation process with the insertion of distributed energy resources, changing from a passive part of the power grid into an active system. Aiming to reduce the challenges for the distribution system operators to keep the power grid operating inside of the quality levels it is possible to propose some ancillary services. Optimum Power flow is an optimization method used to plan the distribution grid operation. Additionally, the distributed energy resources can be modeled on it and ancillary services provisioning can be considered, as proposed in this work. In this way, the objective of the present work is to formulate a Multiperiod Optimum Power Flow (MPOPF) with the insertion of distributed generation, energy storage systems, microgrids, and electric vehicles at the distribution grid. This MPOPF considers the provisioning of ancillary services by the inverters associated with the equipment connected to the main grid. In the formulation, the entire grid is modeled, considering the placement of classic equipment as a voltage regulator and capacitor banks, in addition to modern technologies as DFACTS (Distribution - Flexible AC Transmission System) and four-quadrant inverters. The MPOPF was simulated for several scenarios considering a 90-bus test feeder and a real distribution grid from Curitiba - Brazil. From the results, the MPOPF proved to be highly robust, being able to simulate the grid with all the equipment connected simultaneously, performing the optimal dispatch of active and reactive power, as well as allowing the operation of ancillary services such as voltage support, peak-shaving, and demand-side management.

Highlights

Changes have been happening in distribution systems, being driven by the power system transformation based on 3Ds trends: decarbonization, decentralization, and digitalization
For the simulations with batteries, it is seen that the optimization process realized by the Multiperiod Optimum Power Flow (MPOPF) needs more iterations to reach convergence, going from an average of 10 iterations for the simulations without battery energy storage system (BESS) to 25 iterations with the insertion of the BESS, since it needs to optimize the
With the introduction of solar photovoltaic generation the power losses decrease, since part of the load is supplied by the existing generation nearby, reducing the amount of energy that needs to be delivered by the substation

Summary

Introduction

Changes have been happening in distribution systems, being driven by the power system transformation based on 3Ds trends: decarbonization, decentralization, and digitalization Those three points are being achieved mostly due to the growth of Distributed Energy Resources (DER), such as distributed generation, energy storage systems, electric vehicles, flexible loads, and microgrids, implemented at the distribution network level. The challenges faced by the power utilities are attributable to the DERs that bring many changes, as the two-way power flow, new technical configurations, new business models, and the growth of grid digitalization [1] This new power grid is named Active Distribution Network (ADN) since it is not anymore just a passive system, responsible only for deliver power, but it is a system able to be active in providing power, managing, and controlling power flow [2].

Objectives

Results

Conclusion