Optimal hoist scheduling of a deep level mine twin rock winder system for demand side management

Abstract

This paper presents a near optimal hoist scheduling and control program for rock winders found in South African deep level mines in the context of demand side management and time-of-use (TOU) tariffs. The objective is to achieve a set hoist target at minimum energy cost within various system constraints. The development of a discrete dynamic and constrained mixed integer linear programming model for a twin rock winder system is presented on which a half-hourly model predictive control (MPC) algorithm containing an adapted branch and bound methodology is applied for near optimal scheduling. Simulation results illustrate the effectiveness of the control program by minimising the energy costs through scheduling according to the TOU tariff and controlling output and ore levels within their boundaries even in the case of significant random delays in the system. Scheduling according to the TOU tariff shows a possible 30.8% reduction in energy cost while approximately 6 h of delays in the system resulted in a mere 14% increase in energy cost.

Systems optimization model for energy management of a parallel HPGR crushing process

“…While efforts have been made to improve the comminution efficiency at equipment level in order to decrease the energy cost associated with the comminution process, more energy cost saving can be achieved at the operational level, especially when TOU electricity tariff is applied as the case in many mining industries. The energy management for cost minimization based on TOU electricity tariff has been successfully demonstrated in mining transportation systems [6,7,8,9] as previously discussed. However, the literature shows that there is little research works done in order to improve the energy management of comminution processes, and especially HPGR crushing processes with parallel 4 machines.…”

“…However, due to the continual increase of energy cost, the importance of using systems optimization in minimizing the energy cost of material handling equipment in mining industries is shown in research works such as [6,7,8,9], while in Ref. [10], systems optimization is used for minimal energy cost of a primary jaw crushing process in deep mines.…”

“…[7,8,10,15] are those where open loop systems optimization is applied, while in Refs. [1,2,3,4,5,6,9,11,12,13,14,16], a closed-loop systems 3 optimization is applied.…”

Energy-water optimization model incorporating rooftop water harvesting for lawn irrigation

“…However, domestic consumers are hardly aware of the direct and indirect benefits of the water-energy nexus savings at home [10], such as; energy savings for purifying water, utility pumping and corresponding CO 2 reduction [11], energy savings from the waste water purification and lower cost for potable water and waste water management [12]. Whilst most research in South Africa has concentrated on energy efficiency [13,14,15] and electrical demand side management [16,17,18], little attention has been given to water demand management and its effect on energy consumption [19,20].…”

Optimal maintenance planning for building energy efficiency retrofitting from optimization and control system perspectives

“…The MPC approach finds the optimal control inputs by predicting the future based on the present state of the system, and is inherently robust against disturbances. It has become one of the most widely used control algorithms to solve many industrial control problems in the fields of engineering, food processing, automotive applications, and aerospace applications [28], demand-side management [29] and dispatch of power generation [30]. The control system approach is the second part of our main work.…”