Lastabschaltung

Lastabschaltung, or load shedding, is the deliberate disconnection of electrical loads by a grid operator to prevent system instability or cascading failures when generation capacity is insufficient or transmission constraints threaten the power network. It is used to balance supply and demand during severe energy shortfalls, outages, or extreme demand peaks.

Common forms include automatic under-frequency load shedding (UFLS), where a drop in system frequency triggers sequential shedding to restore balance, and planned or emergency shedding of non-critical loads managed by control systems. Prioritization schemes determine which loads are shed first, typically preserving essential services such as hospitals, water treatment, and critical infrastructure, while non-essential consumers (some industrial, commercial, or residential circuits) are disconnected.

Implementation relies on automation and control systems, such as SCADA, energy management systems (EMS), or advanced distribution management systems (ADMS). Protection relays, remote switches, and circuit breakers execute the shedding according to predefined sequences and restoration plans. Shedding decisions may be manual during unusual events or fully automated for speed and precision.

Impact and considerations: Lastabschaltung causes temporary power outages for affected customers and can influence reliability indices and customer satisfaction. It must be planned with regulatory and contractual frameworks in mind, and restoration should be coordinated to minimize disruption. While a last resort for grid stability, it is designed to be predictable, controlled, and as targeted as possible.