Improved management of power factors on deep-level mines through monitoring and reporting

Abstract

In the last few decades, the South African gold mining industry has been confronted with a decline in mining exploration, reduced productivity, and increased operational costs. The industry is highly dependent on electricity and is one of the main energy consumers in South Africa. Subsequently, the ever-increasing price of electricity has become a major contributor to the escalating operational costs. In recent years, Eskom, South Africa's electricity supplier, has struggled to adequately meet the country's electricity demands. During the peak and standard demand periods of June, July and August, reactive energy charges are used to penalise users with power factors of 0.96 and less. Excess reactive energy increases the total energy demand of a facility and places additional strain on the electrical grid. The reduction in excess reactive energy consumption is vital for the stability of the grid, as this reduces the need for Eskom to resort to load curtailment to reduce the demand which impacts the productivity of electricity-intensive industries such as gold mining. The management of power factors on deep-level gold mines has become increasingly important to mitigate penalties in the wake of inflated electricity prices and grid instabilities. Unfortunately, most mines lack the required tools to effectively monitor and identify poor power factors until it is made evident in the monthly Eskom bill. Therefore, there is a need to improve the identification of poor power factors and the management thereof. This study aims to improve the management of power factors on deep-level gold mines by integrating monitoring and reporting tools to platforms already implemented on the mine, enabling the identification of savings opportunities to reduce penalties and network demand charges through power factor performance. To accomplish this, the waterfall methodology is implemented on the system development life cycle (SDLC) process model to guide the development of the power factor monitoring and reporting tools. These tools comprise a daily performance report, real-time web-based monitoring and data analysis, and notifications via smartphone application integration. The requirements of the tools are established through the shortcomings in the current power factor management approach and will direct the solution implementation. Consumer data is collected and analysed to gather insights into the current state of the power factors and is used for the development of the tools. A case study is used to verify and validate the tools by means of comparative analysis to consumer data and the resulting benefit after implementation. The power factor management tools were implemented on various mining operations in South Africa. The tools were incorporated and made accessible on platforms already implemented on the mines to avoid any additional implementation costs. All relevant personnel were given access to these tools with the necessary notification protocols in place. Penalties on reactive energy usage equating to R3.36 million were identified along with R3.09 million in excess network demand charges through the performance analysis of the case study deep-level mine operations for the 2020/2021 financial year. The analysis of the historic data paired with the reporting and monitoring tools allowed for the prioritisation of underperforming operation points of distribution (PODs). The power factor warning notifications facilitated swift investigation into sudden reductions in power factor performance. This contributed to a R3.4 million reduction (year-on-year normalised) in reactive energy charges and excess network demand charges due to reduced capacitor bank downtime. The study objectives were successfully met through the implementation of the methodology. The findings derived from this study indicate that it is possible to improve power factor management on deep-level mines through daily monitoring, reporting, and notification tools. These tools promote proactive action towards decreasing penalties on excess reactive energy charges and reducing the operational costs attributed to electricity usage. However, it is important to note that alongside these tools, where feasible, adequate power factor correction (PFC) initiatives should be implemented to realise sustained improvement in power factor management.