Ancillary Services Provision by Cross-Voltage-Level Power Flow Control using Flexibility Regions

TL;DR

This paper explores the use of Feasible Operating Regions and Flexibility Regions for cross-voltage-level power flow control to enhance grid stability and support ancillary services, employing advanced optimization techniques for efficiency.

Contribution

It introduces novel methods for using FORs and FRs in CPFC, combining PWL and convex relaxation to improve computational speed and accuracy in medium voltage grids.

Findings

Enhanced network stability through ancillary services provision

Improved computational efficiency with PWL and convex relaxation

Effective control strategies demonstrated on medium voltage grids

Abstract

The large-scale integration of distributed renewable energy sources into the electricity grid requires the investigation of new methods to ensure stability. For example, Active Distribution Networks (ADNs) can be used at (sub-) transmission levels for emergency operation, provided robust and efficient control is available. This paper investigates the use of Feasible Operating Regions (FORs) and Flexibility Regions (FRs) for Cross-Voltage-Level Power Flow Control (CPFC). The enhancement of network stability due to the provision of ancillary services is illustrated, as is the need for strengthened cooperation between Transmission (TSOs) and Distribution System Operators (DSOs). Optimal power flow methods are considered, focusing on computational advances through PieceWise Linearization (PWL) and convex relaxation techniques aiming to speed up runtime while keeping high accuracy. To illustrate the algorithms' benefits and drawbacks, they are analyzed using exemplary medium voltage grids.