Flexibility Measures and Energy Management Strategies for Large-scale PV Integration into Grid system – A Case Study for Saudi Arabia

Abstract

It is widely believed that the incorporation of renewable energy to the current power grid is the way forward in achieving sustainable power generation. Currently, with the reduction of PV prices, many countries have started connecting PV systems into their grid network, hence leading to a sharp increase of the penetration levels of renewable electricity production. In particular, the Saudi government is moving towards exploiting renewable energy, and specifically solar PV to meet its future high energy demands and diversify its economy. This will bring significant change in the load pattern and the ramping requirements of the grid’s conventional generation system due to the varying nature of the renewable energy generation. This significant change affects the stability of the grid frequency, and it becomes more challenging for the system operators to maintain the equilibrium between the generation and load. Additionally, this significant change affects the PV system potential hosting capacity of the traditional grid because of the PV system’s curtailment to comply with the constraints of the grid’s conventional generation system. This thesis aims to investigate and develop flexibility measures and energy management strategies to minimise the impact of integrating large-scale PV systems into the grid system, taking the Saudi Grid as a case study. In doing so, will improve the grid’s flexibility that will result in the enhancement of the grid’s potential hosting capacity with the projected large-scale PV integration into Saudi grid system. This thesis introduces the developed PV curtailment algorithms using MATLAB program, that ensures having the PV system’s participation in the grid’s generation mix at its maximum without violating the grid’s constraints. This enabled studying the change in load pattern effect and the ramping requirements needed by the grid’s conventional generation system in the situation of increasing the penetration level of the large-scale PV power into the grid. In addition, this enabled the evaluation of the grid’s current potential hosting capacity with large-scale PV systems at various penetration levels to the grid. Also, this aided in showing the substantial affects that each grid constraint has on the performance of the PV system in terms of PV curtailment, and provides the bases that can be used to establish the appropriate flexibility measures capable of ensuring both the reduction of the PV curtailment and minimising the impact of integrating large-scale PV into the grid. The results show that the grid operators will face increasingly variable net load patterns and steeper ramping events as the PV system’s penetration level increases in which the PV curtailment percentage will increase from 0.08% to 21.99% as the PV penetration level to the grid increases from 10% to 50%. Additionally, the results show the requirement of having flexibility measures that target each grid constraint as the PV system penetration level increases. Therefore, a diurnal storage system in the form of lithium-ion batteries is proposed to be employed as the flexibility measure for the ramping constraint, while a seasonal storage system is proposed to be employed as the flexibility measure for the baseload constraint. The thesis also examines the grid’s frequency stability due to increasing penetration level of PV generation into the grid. This includes illustrating the effect of the size of the PV disturbance on the grid’s frequency. In doing so, provides insight on the impact of PV variability on the grid, since the frequency stability of the grid senses the variations between the generation and demand. Finally, this thesis introduces the developed optimal sizing and energy management strategies of the proposed flexibility measures to enhance the grid’s PV hosting capacity and minimise the impact of integrating large-sca