A versatile energy management system for large integrated cooling systems Gideon Edgar Du Plessis ⇑,1 , Leon Liebenberg 1 , Edward Henry Mathews 1 , Johan Nicolaas Du Plessis 1 Center for Research and Continuing Engineering Development, North-West University (Pretoria Campus), Suite No. 93, Private Bag X30, Lynnwood Ridge 0040, South Africa article info Article history: Received 27 October 2012 Received in revised form 7 December 2012 Accepted 18 December 2012 Available online 11 January 2013 Keywords: Energy management system Large cooling system Mine cooling Real-time control abstract Large, energy intensive cooling systems are found on deep level mines to supply chilled service water and cool ventilation air to the mine. The need exists for a simple, real-time energy management tool for large, integrated cooling systems. A versatile energy management system was developed for the large cooling systems of deep mines as a typical example of a generic systems-based energy management tool. The sys- tem connects to the SCADA systems of mines and features a hierarchical control function. Set points of various subsystems are optimised in real-time by means of an integrated, systems approach. Real-time monitoring and automatic reporting functions support integrated energy management. In this paper, the development and viability of the system as a practical and versatile energy management platform are presented. In situ experimental results from implementation on four large cooling systems of different designs, sizes and requirements are considered to investigate the potential for such energy management tools. An average electrical energy saving of 33.3% is realised for all the sites without adversely affecting mine cooling requirements. The potential for application to other large cooling systems is also shown. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Sustainable energy systems are priorities in policies of many countries [1]. The International Energy Agency (IEA) has shown that demand-side management (DSM) is more cost-effective than conventional supply-side policies [2]. Effective energy manage- ment largely depends on the type of industry [3]. It has been shown that a major general application area of DSM is cooling sys- tems [4]. Cooling and ventilation is a field that is energy intensive but that also provides many potential areas in which energy usage can be optimised by efficient control. It is therefore a demand sector that promises strong returns in DSM [5] and in which various load management efforts have been made. This is particularly true for the building sector [6]. Building energy management systems (BEMSs) have gained popularity in contributing to continuous energy management of active building systems such as heating, ventilation and air- conditioning (HVAC) systems [7]. BEMS systems have also been extended to interact with renewable energy systems [8,9]. Consid- erable research efforts have been made in recent years to add advanced control methods to BEMS systems. These include fuzzy control [10], genetic algorithms [11], neural networks [12], evolutionary programming [13] and online adaptive control [14]. However, it has been shown that there is still a requirement for simple, integrated energy management methods that provide re- mote control and real-time energy consumption monitoring [15]. Such methods have been presented for building systems by Mari- nakis et al. [6] and Doukas et al. [7]. The advancement of integrated, real-time energy management in building cooling systems is presently not developed to the same degree in industrial processes that are often more energy intensive [16]. Lee et al. [16] developed an energy management system to be used together with facility monitoring and control systems (FMCSs). This system monitors and optimises HVAC and chiller en- ergy consumption of industrial information technology (IT) plants. Vosloo et al. [17] developed a method that simulates, optimises and controls the water reticulation network of a deep level mine. There is a need for a similar system to be developed for large cool- ing systems such as found on deep level mines. South African deep level mines have large, uniquely integrated water and air cooling systems to meet the cooling demands that result from increased mine depths and the associated high temper- atures. These systems typically consume more than 20% of total mine electricity supplies [18] while the mining sector accounts for 14% of the national electricity demand [19]. Considering also that industrial energy use accounts for approximately one third of the world’s energy demand [20], it becomes clear that more emphasis should be placed on improving the energy efficiency of large mine cooling systems. This paper presents a simple, integrated, real-time energy man- agement system that can be applied to a variety of large cooling systems as found on deep mines. The system is presented as a typ- ical example of a generic, integrated energy management tool and 0196-8904/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.enconman.2012.12.016 ⇑ Corresponding author. Tel.: +27 (0)12 809 2187; fax: +27 (0)12 809 5027. E-mail address: dduplessis@rems2.com (G.E. Du Plessis). 1 Consultants to TEMM Intl. (Pty) Ltd., and HVAC (Pty) Ltd. Energy Conversion and Management 66 (2013) 312–325 Contents lists available at SciVerse ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman