Synthetic Inertia Requirements for Optimal Participation in Under Frequency Transients and System Recovery

摘要

The aim of this investigation is to set requirements for optimal participation of battery energy storage systems in ancillary services. In this case the target is to maintain or improve the frequency nadir following loss of generation events. Phasor measurement unit data from approximately 50% of the generators on the island of Ireland is analysed for three under frequency events. In each event approximately 14% of generation was lost resulting in a frequency nadir of 49.25 ±0.02 Hz. For each event the quantity of additional power delivered from generation sources, during the first 6 seconds, is estimated based on Phasor measurement unit and market participation data. It is surmised that additional energy delivered before the frequency nadir directly determined the severity of the nadir. The quantity of power that might be delivered by battery storage systems, with varying operational parameters, is quantified. The results support the conclusion of Ireland's TSO that 360 MW would be optimal to support the 75% renewable penetration required by 2020. Presented in this investigation is the response of the 10 MW grid connected battery storage project in Northern Ireland. It is determined that the BESS provided 53% of the maximum possible energy that it could deliver before the frequency nadir. The factors that determine the 53% figure are displayed and potential methods of improving this figure suggested. The potential for a large per unit displacement of synchronous generation by storage solutions is demonstrated using the battery response data. Under frequency transients on the Irish system tend to be cleared in 15 seconds, this places a very small demand on battery capacity suggesting that for this type of service provision investment should be focused on the inverter power capacity.