Position Paper

The position paper “Grid-Forming Readiness in Distribution Grids” examines the systemic challenges facing the energy industry in the transition toward a power system dominated by power electronics. It highlights the growing importance of inverter-based resources – particularly large-scale battery storage systems in medium-voltage grids – and explains why future stability, resilience, and restoration functions should already be considered in today’s technical design.

At its core, the paper introduces the concept of Grid-Forming Readiness. This describes the proactive provision of grid-forming capabilities without mandating immediate activation or operational obligation. The paper identifies a conceptual and regulatory gap between the current operational state and future system requirements and develops a framework to ensure long-term operational flexibility, investment security, and system resilience. It also outlines concrete next steps for technical implementation.

Call for Action

Prepare Grid-Forming Readiness in distribution grids – start now

Regional islanding capability and resilience are becoming strategically important as the energy system transforms. The ability to stabilize or restore isolated sections of the grid when needed is becoming a key prerequisite for security of supply in a system increasingly dominated by power electronics.

Phase 1: Focus on Medium-Voltage Battery Storage

In an initial phase, specification efforts should explicitly focus on large battery storage systems connected to medium-voltage grids because:

• they are particularly well suited technologically,
• they are typically accessible via communication systems,
• their system impact is significant at both local and regional levels,
• regulatory implementation appears manageable.

A later extension to other technologies and voltage levels is possible but should be based on practical experience.

Further Development of the Concept – Concrete Steps

• Update and prioritize use cases for grid-forming assets, including islanded operation, black start capability, weak grid support, provision of fast frequency response (inertial-like response), and emergency energy reserves
• Introduce standardized functional classes that assets can certify through defined testing procedures
• Precisely define “Grid-Forming Readiness” and verification methods for technical classes within standards (VDE|DKE) and application rules (VDE|FNN)
• Implement the concept in the regulatory framework

Overview of the Position Paper’s Content

The paper frames the energy transition as an infrastructure challenge: as rotating masses are replaced by power-electronic-based systems, fundamental system behavior changes. Frequency and voltage stability, short-circuit strength, fault response, as well as islanding and restoration capabilities are becoming increasingly important – even at the distribution level. This creates growing demand for regulatory and design action to ensure stable operation under disturbed conditions and to enable regional resilience concepts.

Against this background, the paper analyzes existing terminology such as grid-following and grid-forming, along with current regulatory and standardization approaches, highlighting their limitations. It argues for the need for an additional category that captures forward-looking operational capability between present-day operation and future system responsibility.

Building on this, Grid-Forming Readiness is introduced as a structured classification and preparedness concept. Objectives, structure, a two-stage classification model, activation dimensions, and testing procedures are explained and positioned within existing technical definitions and regulatory frameworks.

Another key focus is the systemic benefit: Grid-Forming Readiness enables early preparation for future stability and resilience functions, separates technical feasibility from eventual activation, and avoids costly retrofitting programs. Large battery storage systems in medium-voltage grids are highlighted as a particularly suitable starting point.

Finally, the paper presents perspectives from key stakeholders – ranging from asset operators and manufacturers to grid operators, policymakers, regulators, and standards bodies – and discusses implementation and financing aspects. It concludes by outlining concrete next steps, including prioritizing use cases, defining standardized functional classes, refining the technical definition of Grid-Forming Readiness, and integrating it into relevant regulatory frameworks.