Learning from a 3.275 MW utility scale PV plant project

This paper presents some findings relevant to performance and grid integration challenges of large solar PV plants obtained by analysing the operational data from a 3.275 MW solar PV plant in Queensland, Australia. The plant is a research infrastructure, funded by the Australian Federal Government, which contains state of the art technologies - such as different PV tracking systems, battery energy storage system, smart metering and control systems that need substantial research and investigation to ensure the best utilisation of these new technologies. This paper is an initiative to communicate the learnings from this facility based on the data from its initial operation for industry and the research community. The paper contains four main sections. Section 1 briefly introduces the context and the motivation of the paper, which is followed by a description of the plant in Section 2. This section provides details of the plant components including PV panels, inverters, battery storage, smart metering and the control system. Plant interconnection with the local grid and the relevant connection agreement is also briefly discussed here. Section 3 presents the observations on plant performance and its impact on the grid by analysing operational data - which is the main purpose of this paper. At first, plant yield performance is analysed using AC energy output and rated capacity of individual arrays on a daily and monthly basis. Output smoothing of PV plants having arrays distributed over a large geographical area is a reported observation for large PV plants. This phenomenon is verified in this paper using inverter level and plant level ramp rate data. Network voltage variation as a result of PV power variation is then investigated using PV output and voltage profile data corresponding to high PV variability days. Steady state and rapid voltage variations - both types are investigated in the context of recommended limits. This is then followed by flicker analysis to investigate whether and how the plant affects short term and long-term voltage flicker emission limits. Finally, Section 4 provides a brief conclusion on what has been observed from the operational data, emphasising the fact that the duration of the data was only a few months and is also affected by technical issues which is normal at initial periods of operation. Therefore, the analysis outcome is not conclusive and further investigations are needed to fully understand the plant performance and relevant network impacts.