Desenvolvimento de uma metodologia para avaliação da flexibilidade operacional entre sistemas de transmissão e distribuição

Abstract

This master’s thesis has as its central focus studies related to flexibility in Electric Power Systems (EPSs), especially with an emphasis on obtaining Flexibility Regions (FRs), which are maps in the PQ plane capable of representing the operational capacity in a given bus of a system. First, a review is carried out regarding the main definitions and concepts directly or indirectly related to the theme. This review also addresses the roles of transmission and distribution system operators in the context of the integration of Distributed Energy Resources (DERs) and the need for interaction between them to ensure network security and service quality. In addition, a review of works that approach the construction of FRs is carried out, highlighting construction methodologies and their main characteristics, as well as possible applications involving them in the context of providing ancillary services. After the literature review, a detailed review of an FR construction method based on Optimal Power Flow (OPF) is performed, highlighting its algorithm and implementation carried out in this work. Furthermore, the so-called Flexibility Coefficients (FCs), used to quantify the flexibility in the interface between the Transmission System Operator (TSO) and the Distribution System Operator (DSO) (TSO/DSO interface), are discussed. As with most FR construction methods observed in the literature, the revised approach has limitations in representing non-convexities in the FR area. Therefore, it was proposed in this work a construction method capable of representing them called the Angular Sweep Method. The proposed method is based on successive solutions of an OPF in different directions in the PQ plane. Furthermore, mathematical models are proposed to represent, in the OPF modeling, distinct models of flexible resources. A method of construction of FR segmented by electrical loss levels, capable of showing the level of electrical losses that the system will assume when deviating from its operating point at the TSO/DSO interface, is also proposed. Based on the theory addressed, case studies are presented to evaluate the methodologies and explore the application of the FRs. The results show the ability of the proposed method to represent a more reliable FR than the method found in the literature, analyzing, among others, the computational cost and the coverage areas of the FRs obtained by each method. It also observed the applicability of the FCs to the identification of the best connection points between transmission and distribution systems. The validation of flexible resource models inserted in the OPF and their impacts on the resulting FR are also presented, as well as the construction of the segmented FR.