ReviewIndustrial power and energy metering – a state-of-the-art review
Highlights
► We review the state-of-the-art in industrial power and energy measurement devices. ► We examine different power and energy measurement technologies. ► The impact measurement resolution has on device cost is investigated. ► The benefits of energy and power measurement in an industrial context are explained.
Introduction
Demand for energy has become so intense in the recent past that it has outgrown supply and this presents governments worldwide with the difficult task of guaranteeing a secure long term energy supply. According to the International Energy Agency (IEA) the worlds energy requirement could be 50% higher in 2030 than it is today and this would have alarming economic and environmental consequences (International Energy Agency Technical Staff, 2010). If global energy consumption trends continue on their current path without any change in government policy there would be alarming repercussions from a climate change perspective (International Energy Agency Technical Staff, 2009). Having already increased from 20.9 gigatonnes (Gt) in 1990 to 28.8 Gt in 2007, CO2 emissions are projected to reach 34.5 Gt in 2020 and 40.2 Gt in 2030 (International Energy Agency Technical Staff, 2009). Already the ramifications associated with climate change are clear; four years after the Intergovernmental Panel on Climate Change's fourth assessment report was published, scientific evidence shows an acceleration of climate change patterns and a deepening of the climate crisis: sea levels are rising, oceans are acidifying and ice caps are melting much quicker than initially anticipated (European Wind Energy Association (EWEA), 2011).
Action needs to be taken sooner rather than later and a myriad of governmental organisations have published documents on the severity of the current situation while also outlining the reasons why immediate action is necessary. The industrial sector, responsible for almost one quarter (24%) of total European energy consumption has a responsibility to reduce its overall consumption and increase efficiency (Sustainable Energy Authority Ireland (SEAI), 2010). Complex manufacturing facilities consume a significant amount of the industrial sectors electrical energy; it is used to power motors, compressors, machine tools and it is also required to maintain adequate heating, ventilation and air conditioning. As a result of the looming energy crisis outlined above, falling profit percentages and an increased emphasis on value for money, the implementation of lean strategies and energy management have become increasingly prevalent within the manufacturing sector (Thollander and Dotzauer, 2010). Due to this shift toward energy efficiency, there is a need to effectively manage all energy related procedures (Nielsen and Wenzel, 2002). Before energy consumption can be effectively managed, it must first be accurately quantified; power metering facilitates this quantification and allows the development of an awareness and understanding of where, why and how much energy is being consumed within an industrial facility.
Section snippets
Energy metering enabling a sustainable energy future
In order to overcome the climate and energy challenges that we are now facing, major changes are required. For a successful global transition to sustainable development it is necessary to more efficiently integrate academic results and insights with practical applications in society (Bonilla et al., 2010). Similarly there is an urgent need for decision makers to develop and implement proactive, integrated policies and strategies that will assist societies manage all resources in a more
Energy metering systems
Researchers have been proposing methodologies to correlate production to energy consumption for many decades (De-Filippi et al., 1980). It is only now that industrial enterprises are being forced to consider this link that electrical energy measurement and monitoring have become widespread outside of research labs. It is widely accepted that before power consumption in manufacturing facilities can be reduced it is first necessary to quantify the amount of energy needed, to determine the degrees
Current and voltage sensing
Industrial power meters require voltage and current measurements in order to calculate power consumption and to produce more complex power quality statistics such as sags, peaks, and harmonics. The accuracy of a power meter is a function of the measurement error associated with the current and voltage sensing equipment (Kara et al., 2011). Current sensing is the more difficult of the two as it requires a wider measurement range and also needs to handle a broader frequency range because of the
Measurement resolution
Power metering equipment can identify a large variety of events depending on the sampling rate, accuracy and resolution of the device. Small sampling rates are only necessary in order to obtain basic information including minimum, average and maximum power values. Alternatively, very high sampling rates are required in order to identify transient events that appear and disappear within a fraction of a second. Measurement instruments are available for all possible power measurement scenarios;
Inference/decision making
The installation of power measurement equipment provides information that is used for various purposes depending on the facility level that is metered. The implementation of a well planned energy metering system within a complex manufacturing facility provides a level of energy transparency and understanding that is typically only available in research labs. A combination of 1st, 2nd, and 3rd order metering devices installed at all levels of the facility will allow the collected data to be used
Communication platforms and protocol for energy and power monitoring
As industrial facilities evolve, the networks existing within these facilities are changing from centralised to distributed architectures and this is challenging for plant wide assessment of energy consumption. The communication method utilised by an industrial power meter determines the transmission quality, i.e. the speed, distance, and electromagnetic immunity. Industrial facilities are typically affected by strong electromagnetic power sources such as motors, and welders which reduce
Regulation and certification
As a result of the complex nature of industrial power metering, the constantly increasing number of solutions available to the consumer, and the varying measurement principles employed by different meter manufacturers, international standards have been developed to verify meter performance (Kara et al., 2011). An extensive list of relevant regulations is included below and a brief overview of some of the most important standards follows. EN50160 Supply Voltage (EN50160, 2010) IEC 62053-22 Class
Energy metering costs and industrial marketplace
The cost of power metering equipment is highly variable depending on functionality. There are a number of influencing factors that affect the unit cost of a power meter; the primary drivers are the number of samples recorded during each cycle in addition to the meters measurement accuracy and resolution. Fig. 8 plots the smallest duration transient identifiable by a meter against its cost in order to highlight the cost impact associated with increasing meter complexity.
The main difficulties
Conclusion
Analysing the overall efficiency of manufacturing systems by combining electricity consumption data with additional facility level or process level information has been investigated by many researchers with promising results (Vijayaraghavan and Dornfeld, 2010; Rahimifard et al., 2010), however, there is scant attention given to the challenge of choosing the correct power metering solution within the literature. Choosing the correct metering device for the required analysis is a challenging task
Acknowledgements
The authors would like to thank the Irish Research Council for Science, Engineering, and Technology for their funding of this research under the EMBARK initiative.
References (77)
- et al.
Evaluating the use phase energy requirements of a machine tool system
Journal of Cleaner Production
(2011) - et al.
Development of SuperSmart Grids for a more efficient utilisation of electricity from renewable sources
Journal of Cleaner Production
(2009) What is power quality?
Electric Power Systems Research
(2003)- et al.
The roles of cleaner production in the sustainable development of modern societies: an introduction to this special issue
Journal of Cleaner Production
(2010) - et al.
Emergy evaluations and environmental loading of electricity production systems
Journal of Cleaner Production
(2002) - et al.
Forecast of the electric energy requirement in a mechanical plant by using a Stochastic model
CIRP Annals - Manufacturing Technology
(1980) - et al.
Industrial ecology at factory level - a conceptual model
Journal of Cleaner Production
(2012) - et al.
Cleaner energy for sustainable future
Journal of Cleaner Production
(2009) Measuring electric power quality: problems and perspectives
Measurement
(2008)- et al.
Wired and wireless sensor networks for industrial applications
Microelectronics Journal
(2009)