1. Background

Over the last two decades, the European power system has undergone a profound transformation driven by the large-scale deployment of converter-based renewable generation. Wind, solar PV, and battery energy storage systems now account for several hundred gigawatts of installed capacity. While enabling deep decarbonization, this shift has fundamentally altered system dynamics, leading to reduced synchronous inertia, declining short-circuit power, and increased sensitivity to voltage and frequency disturbances.

Grid codes have evolved accordingly, extending beyond basic power factor requirements toward deeper fault ride-through, dynamic voltage control, frequency–active power interaction, and, more recently, grid-forming capabilities. However, most existing renewable and BESS plants still operate strictly at their original compliance level. In many cases, modern converter platforms already embed advanced control functionalities that were not activated at commissioning because they exceeded the regulatory requirements in force at the time.

This work introduces the concept of Latent Grid Support Capability (LGSC), defined as the set of technically feasible but currently inactive grid support services embedded within existing inverter-based assets. Activating LGSC through parameter adjustments, firmware upgrades, or limited retrofitting—without major hardware replacement—represents an underexplored opportunity to reinforce system stability rapidly and cost-effectively.

2. Objective and Methodology

The objective of this work is to develop a structured framework to assess the additional grid support services that existing wind, solar PV, and BESS installations could provide beyond their original compliance obligations. The focus is explicitly on the already-installed fleet, complementing research that primarily targets new-build assets.

The assessment is structured around four capability domains:

(1) enhanced fault ride-through performance, including extended LVRT and partial HVRT;

(2) dynamic voltage control through closed-loop regulation and Q–V droop;

(3) frequency–active power interaction, including P–f response and fast frequency support; and

(4) partial transition toward grid-forming behavior, such as synthetic inertia within existing hardware limits.

The methodology combines technology mapping by commissioning period, benchmarking grid code evolution, technical feasibility and constraint analysis, and identification of regulatory and economic enablers. The integrated outcome is a LGSC Capability Matrix linking converter generation, technically feasible services, and original grid code obligations to concrete implementation pathways, costs, complexity, and risks.

3. Expected Results

The study is expected to show that a significant share of post‑2015 installations can deliver enhanced fault ride-through, dynamic voltage control, and frequency support with low implementation complexity. Limited HVRT and partial grid-forming functionalities are anticipated to be feasible in recent converter generations, subject to current and control constraints.

At system level, coordinated activation of LGSC across part of the existing fleet could significantly improve stability margins, reduce reliance on capital-intensive infrastructure, and accelerate resilience in weak-grid regions.