Development Of A Smart Control And Monitoring System For Impressed Current Cathodic Protection Running On Hybrid Renewable Energy

Abstract

Underground pipelines play a significant role throughout the world as a means of transporting potable and raw water, oil and gases over distances of various lengths; from the source to the ultimate consumers. In South Africa, particularly in KwaZulu-Natal, these pipelines run mostly in remote mountainous areas, to achieve shorter routes. Due to high connection costs and low electricity consumption rate for Cathodic Protection (CP) systems, a remote electrification through grid extension is needed, which is a challenging solution. Furthermore, it is difficult to recover the initial investment costs, as monthly electricity payments are made for each Transformer Rectifier Unit (TRU), installed along the servitude pipeline. This Dissertation discusses the use of renewable energy sources, namely, the wind and solar, powering the Impressed Current Cathodic Protection (ICCP) systems, providing protection against corrosion of underground pipelines used for distribution. In this study, an off-grid hybrid wind-solar photovoltaic (PV) system is used, to supply DC current to an ICCP system, with the aim to eliminate the need for grid power in remote CP systems, while further optimizing the running costs. However, due to the unavailability of continuous energy from the sun and the wind, energy storage systems are required to ensure the continuity of power supply, hence improving the reliability of the system. To demonstrate the technical and economic feasibility of an off-grid hybrid wind-solar PV system, a TRU site located at Ndwedwe Reservoir 2, in Durban, is used as a case study, as this site contains adequate wind and solar irradiance. The purpose of this study is to investigate the technical and cost effectiveness of the proposed off-grid hybrid renewable energy system, by making use of the renewable resources, whilst eliminating the use of grid electricity to supply CP systems. The sizing of the proposed system is performed using a Hybrid Optimization Model for Electric Renewable (HOMER). The model is then simulated to evaluate the technical performance of the system using MATLAB/Simulink. Furthermore, the baseline system is established, which consists solely of energy supplied by the grid. The proposed system is simulated and compared to the baseline system. The simulations showed that the system successfully meets the load demand, for various operating conditions, in a South African case. The prototype of the proposed system is finally carried out to test the smart control and monitoring of the CP system, with the unit being supplied by wind and solar energy. The obtained results reflect that the proposed system is feasible, implementable and viable. The economic analysis is conducted for a projected period of 25 years, for both the baseline and the proposed system. Results from the analysis indicate that the proposed system would break-even within the first 3 years, with an approximate saving of 87%, translating into savings of R 2 438 259.34, while giving a “true” payback period of 10 years. This clearly demonstrates that the user could save significant energy costs if the system is implemented. Nonetheless, the study further showed that the use of renewable energy in the CP may be beneficial for pipeline users in South Africa and beyond.