Improved control processes to sustain electricity cost savings on a mine water reticulation system

Abstract

Eskom provides the majority of South Africa's electricity. However, Eskom's maximum generating capacity might not be sufficient to meet South Africa's demand in the future. Therefore, Eskom initialised the Demand Side Management (DSM) initiative to reduce electricity consumption in South Africa. The benefit of this initiative was seen as the DSM target was achieved 10 years earlier than anticipated. The mining industry is a large energy consumer and implemented numerous demand management projects. The deep level mining industry is a harsh environment with high humidity and temperatures in underground working areas. These conditions can lead to critical component failures that negatively affect demand management control strategies, which has a detrimental effect on electricity cost savings. New processes and control strategies are required for load demand control projects when critical components fail. From an extensive literature review it is shown that various problems were identified and solved for water reticulation systems. At the time, no methods or processes were found that mitigated the reduction in load demand shifting when a critical component failure occurred on a mine water reticulation system. These new processes on control strategies is listed as the first novel contribution of the study. Two prediction models were developed and used as tools in the formulation of each control strategy, namely, the dam level prediction model and the load demand prediction model. A process was developed to formulate control strategies per water reticulation system. A digital twin was used for the study. A digital twin is a term used for a verified simulation of the entire system. Each control strategy was developed per relevant component failure and simulated in the digital twin.Improved control processes to sustain electricity cost savings on a mine water reticulation system ii All possible control strategies were tested on a case study and the remaining control strategies were validated with a digital twin. Each control strategy and its effects are discussed with regard to safety and load demand reduction. Implementing each control strategy in a digital twin and evaluating the effect of a failure and a control strategy was the second novel contribution. These control strategies were implemented on a gold mine in South Africa. For this case study, the approximate increase in annual electricity cost savings equated to R3.8 million. These electricity cost savings were achieved without requiring any capital expenditure for implementation. The results showed that the implementation of the new electricity cost reduction control processes and strategies for failure conditions increased the electricity cost savings. These cost savings were achieved without adding additional risks. Improved control processes to sustain electricity cost savings on a mine water reticulation system.