This project will perform the pre-normative research required to develop new IEEE/IEC/CENELEC standards for rate-of-change-of-frequency (ROCOF) measurements in electricity networks. Network frequency and changes in network frequency are key indicators of network stability and of the balance between electricity supply and demand. This balance is becoming more critical with the increased use of highly-variable renewable energy sources (RES) for electricity generation, and at the same time present ROCOF measurements are inadequate for monitoring this balance.


The increased use of RES is essential if the EU is to meet its 2020 objective of 20 % renewable electricity generation and its further 2050 objectives of at least 50 % renewable electricity generation. Traditional carbon‑based electricity generation uses massive rotating machines which provide significant inertia to the grid, able to absorb unpredictable changes in consumer demand. They also act as voltage sources, leading to an almost “perfect” power quality (PQ). By contrast, RES are connected to the network via power-electronic converters. These generally provide negligible contribution to grid inertia, and often have a strong negative contribution to PQ. PQ is further degraded by other new emerging grid components like HVDC (High Voltage DC) Links, and electric vehicle chargers, which are also converter-connected to the grid. ROCOF is required as a metric of system inertia in order for network operators to take control actions in order to maintain system stability. Poor PQ and other short lived events on the electricity supply can cause large ROCOF errors which would lead to false control actions. It is therefore important to understand the conditions in which ROCOF needs to be measured by surveying possible network operational scenarios. Algorithms can then be selected and configured to measure ROCOF and the limitations and eventual expectations of the measurement can be understood, such that control strategies can be pursued by network operators with confidence. IEC/IEEE TC95 WG1 have therefore called for research to be carried out to address the lack of standardisation in this area.