January 8, 2015

Loss measurement accuracy as key factor for energy saving programmes

Abstract Most government efficiency programmes focus on reducing energy losses in the distribution network and for some of them even provide metrics for these improvements....

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Abstract

Most government efficiency programmes focus on reducing energy losses in the distribution network and for some of them even provide metrics for these improvements. A large amount of these losses comes from distribution transformers and the manufacturers are encouraged to improve the efficiency of their designs. These improvements are often managed with the use of better materials and then increase of transformer costs. The need for accurate loss measurements is therefore increased if the manufacturers do not want to their efforts to be affected by the measurement uncertainties of a measurement system. Proving a small improvement in efficiency, even at high cost for the manufacturer, will be difficult if the measurement system cannot measure this improvement accurately. Accuracy of measurement systems and comparison of the accuracy are of the utmost importance and have been a topic of discussions among experts for years. The article will describe how a modern measurement system can be accurate, assess its accuracy for every measurement performed and confirm the stability of their accuracy over time. In this approach, not only is the measurement important, but also the complete chain, data management, reporting and accuracy assessment of the measurement have to be automatically computed for the end user.

Keywords: efficiency, loss-measurement, uncertainties, accuracy, temperature, accuracy assessment

Analysis of current situation

Transformer loss measurement is a well known field. All transformer manufacturers have to perform loss measurement tests to confirm the technical data of their products especially for load losses and no load losses. It is stated in many studies and articles that general loss of the transmission and distribution network is around 9 % in total [1]. The losses generated by transformers form the second largest part of the total distribution and network losses. It is stated that the losses caused by transformer load and no load losses have an approximate value of 300 TWh per annum – approximately twice the annual consumption of Poland [2]. Efficiency programmes worldwide are trying to force manufacturers to invest in R&D and production to achieve lower losses. Speaking of losses, we have to state that the efficiency values of transformers are already in a quite high range. Fig. 1 shows the efficiency values for liquid filled transformer tiers.

Figure 1: Liquid filled transformer tiers – efficiency values [1]

Figure 2 shows a variety of international programmes for energy efficiency and illustrates a trend for the future. Many countries will propose programmes like this to force transformer manufacturers to reduce the losses of their products.

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