Using Active Distribution Network Flexibility to Increase Transmission System Voltage Stability Margins

TL;DR

This paper proposes a framework for quantifying the operational flexibility of active distribution networks with DERs and uses it to enhance transmission system voltage stability margins through centralized optimization.

Contribution

It introduces two methods to calculate the flexibility region of active distribution networks and applies centralized optimal power flow to improve voltage stability margins.

Findings

Flexibility region calculation methods are effective.

Centralized optimization improves voltage stability margins.

Applicable to various transmission and distribution configurations.

Abstract

The increasing penetration of Distributed Energy Resources (DER) in the distribution network creates new challenges in the operation of both the transmission and the distribution network. However, the controllability of the converter interfaced devices (CIG), also unveils opportunities for flexible operation and provision of ancillary services with or without economic incentives. The main scope of this work is to create a framework in order to calculate the operational flexibility of an Active Distribution Network and use it to address a centralized Optimal Power Flow Problem by the Transmission System Operator, and in particular the Voltage Stability Margin maximization. Two different approaches are proposed to calculate the Flexibility Region (FR) in the PQ plane, and the centralized optimization is applied to simple and more complex transmission test systems and feeder configurations.