Grid Forming and Phase Locked Loop Modelling and Analysis

Tender description

The recently published Government of Ireland Action Plan requires that 70% of total annual electrical demand in Ireland is to be met by renewables by 2030. Although there is currently no similar renewables target for 2030 in Northern Ireland, it is very likely that Northern Ireland will be aligned with the 2050 carbon neutrality ambitions of the UK. This would require Northern Ireland to follow a similar trajectory to Ireland in terms of renewable generation integration. Integrating very high levels of variable non-synchronous renewables will pose a number of considerable technical challenges for operation of the All-Island power system. Achieving the 70% total annual electrical demand to be met by 2030 will require system operation at instantaneous non-synchronous renewable penetration levels as high as 90% to 100%. Operation of the system under such conditions is also the subject of a horizon 2020 project led by EirGrid called the EU-Sysflex project. The system modelling conducted under the EU-Sysflex project needs to be critically evaluated for applicability to weak systems with very high non-synchronous renewable penetration. One specific and important aspect of this modelling is the assumed behaviour of phase locked loop (PLL) controllers at very low system strength conditions. The PLL behaviour as assumed by the EU Sysflex project requires critical evaluation supported by physical evidence. Potential discrepancies between the assumed and observed PLL behaviour needs to be represented through updated PLL models. Additionally, grid forming control configurations can potentially be a key enabler for high non-synchronous renewable penetration levels, specifically the configurations which do not rely on PLL measurements and are suitable for operation at low system strength conditions. An overview of such configurations is required, followed by a recommendation for the most suitable configuration for the all Island system, in consultation with the innovation team