Determination of the Required Power Response of Inverters to Provide Fast Frequency Support in Power Systems with Low Synchronous Inertia

Alejandro Rubio,Stefan Geißendörfer,Holger Behrends,Karsten Von Maydell,Carsten Agert

doi:10.3390/en13040816

Abstract

The decommissioning of conventional power plants and the installation of inverter-based renewable energy technologies decrease the overall power system inertia, increasing the rate of change of frequency of a system (RoCoF). These expected high values of RoCoF shorten the time response needed before load shedding or generation curtailment takes place. In a future scenario where renewables are predominant in power systems, the ability of synchronous machines to meet such conditions is uncertain in terms of capacity and time response. The implementation of fast power reserve and synthetic inertia from inverter-based sources was assessed through the simulation of two scenarios with different grid sizes and primary reserve responses. As main results it was obtained that the full activation time for a fast power reserve with penetration above 80% of inverter-based generation would need to be 100 ms or less for imbalances up to 40%, regardless of the synchronous response and grid size, meaning that the current frequency measurement techniques and the time for fast power reserve deployment would not ensure system stability under high unbalanced conditions. At less-unbalanced conditions, the grid in the European scale was found to become critical with imbalances starting at 3% and a non-synchronous share of 60%.

Highlights

As part of the international efforts set to counteract global warming, the deployment of renewable energy sources in the electric sector has been considered an energetic priority as a measure to reduce CO2 emissions
This is because the critical time is long enough to allow for the governor response activation of the respective synchronous machine’s representation
It can be stated that the simplifications made in the model have a greater influence on the results for low values of IBG penetration and low power imbalances

Summary

Introduction

As part of the international efforts set to counteract global warming, the deployment of renewable energy sources in the electric sector has been considered an energetic priority as a measure to reduce CO2 emissions. This objective is reflected in the regulatory energy policies and plans of some countries. In Germany, the transformation of the electricity sector contemplates achieving a share of electricity generation of 80% from renewable energy by 2050 As part of such transformation, the expansion of renewables and the decommissioning of conventional power plants is regulated by the “Erneuerbare. Balancing of the residual load is provided by conventional units, so curtailment of renewable energy resources is the least preferred option for power balancing [3]

Methods

Results

Conclusion