Lecture
This lecture discusses the practical challenges and current developments related to ancillary services from the Transmission System Operator (TSO) perspective. Topics include horizontal and vertical coordination, balancing markets, legal provisions, voltage control, integration of controllable resources, and collaboration between TSOs and Distribution System Operators (DSOs). The presentation also covers the role of active distribution grids and aggregators in providing ancillary services to the transmission system, as well as the collaborative framework between TSOs and DSOs for efficient use of controllable resources.