Iso efficiency contour measurement results for variable speed drives

Abstract:In district heating stations, the heat carrier is circulated between the energy source and consumers by a pumping system. Fluid handling systems, such as pumping systems, are responsible for a significant portion of the total electrical energy use. Significant opportunities exist to reduce pumping energy through smart design, retrofitting, and operating practices. Most existing systems requiring flow control make use of bypass lines, throttling valves or pump speed adjustments. The most efficient of these options is pump speed control. One of the issues in using variable-speed pumping systems, however, is the total efficiency of the electric motor/pump arrangement under a given operating condition. This paper provides a comprehensive discussion about pump control in heating stations and analyzes the energy efficiency of flow control methods. Specific attention is also given to the selection of motor types, sizing and pump duty cycle. A comparative energy analysis is performed on the hot water discharge adjustment using throttling control valves and variable-speed drives in a district heating station constructed in Romania. To correlate the pumped flow rate with the heat demand and to ensure the necessary pressure using minimum energy, an automatic system has been designed. The performances of these control methods are evaluated in two practical applications. The results show that approximately 20%-50% of total pumping energy could be saved by using the optimal control method with variable-speed pumps. Additionally, some modernization solutions to reduce the environmental impact of heating stations are described. OPEN ACCESSSustainability 2015, 7 5706

show abstract

“…Stockman et al [27] demonstrated that the brushless PM motor/VFD has far better efficiency values compared to the IM/VFD.…”

Section: Variable Frequency Drivesmentioning

confidence: 99%

Energy Savings Potential for Pumping Water in District Heating Stations

Sârbu

Valea

2015

Sustainability

View full text Add to dashboard Cite

show abstract

“…Choose this temperature or a temperature slightly lower as test temperature. 6) For a chosen matrix of test points [19], the measurements are performed. Preferably, start with choosing a (nearly) fixed speed and 'scan' the preferred load points starting with the highest torque until the lowest partial load point.…”

Section: Testing Protocolmentioning

confidence: 99%

“…More information on the choice of the test matrix, required density of test points and accuracy linked with such interpolations can be found in [19].…”

Section: Testing Protocolmentioning

confidence: 99%

Iso efficiency contours as a concept to characterize variable speed drive efficiency

Deprez

Lemmens

Vanhooydonck³

et al. 2010

The XIX International Conference on Electrical Machines - ICEM 2010

View full text Add to dashboard Cite

Φ Abstract --Despite recent revisions and harmonization efforts of international motor efficiency standards which has lead to the revised IEC Std 60034-2-1 and the efficiency classification of IEC Std 60034-30, there remains a lacuna in the context of motor systems efficiency. Although IEC is preparing a "Guide for the selection and application of energyefficient motors including variable-speed applications" labeled IEC Std 60034-31, to date, there is no internationally accepted test protocol that allows the determination of drive system efficiency at different load points. As the first in a set of three by a joint research project of three research institutes, this paper introduces iso efficiency contours as a useful tool in this context. The concept of these contours as well as their mutual interaction with system specifications and losses are discussed. A first testing protocol for all types of motor drives is proposed. The concept is illustrated by first results of an extensive testing campaign.

show abstract

“…Internationally approved standards or testing procedures of motor/VFD combination are not available at present (Stockman et al, 2010). Since the variable frequency drive can operate the motor over a wide range of speeds, it is important to know efficiency values of VFD/motor combination at each operating point to accurately determine the operating point of a pump, which is known as iso-efficiency contours.…”

Section: Variable Frequency Drivesmentioning

confidence: 99%

“…Since the variable frequency drive can operate the motor over a wide range of speeds, it is important to know efficiency values of VFD/motor combination at each operating point to accurately determine the operating point of a pump, which is known as iso-efficiency contours. Stockman et al (2010) have reported a successful measurement procedures how to…”

Section: Variable Frequency Drivesmentioning

confidence: 99%

Assessing variable speed pump efficiency in water distribution systems

Marchi

Simpson

Ertugrul

2012

Drink. Water Eng. Sci.

View full text Add to dashboard Cite

Abstract. Energy savings and greenhouse gas emission reductions are increasingly becoming important design targets in many industrial systems where fossil fuel based electrical energy is heavily utilised. In water distribution systems (WDSs) a significant portion of operational cost is related to pumping. Recent studies have considered variable speed pumps (VSPs) which aim to vary the operating point of the pump to match demand to pumping rate. Depending on the system characteristics, this approach can lead to considerable savings in operational costs. In particular, cost reductions can take advantage of the demand variability and can decrease energy consumption significantly. One of the issues in using variable speed pumping systems, however, is the total efficiency of the electric motor/pump arrangement under a given operating condition. This paper aims to provide a comprehensive discussion about the components of WDS that incorporate variable speed pumps (including electric motors, variable frequency drives and the pumps themselves) to provide an insight of ways of increasing the system efficiency and hence to reduce energy consumption. In addition, specific attention is given to selection of motor types, sizing, duty cycle of pump (ratio of on-time and time period), losses due to installation and motor faults. All these factors affect the efficiency of motor drive/pump system.

show abstract

Iso efficiency contour measurement results for variable speed drives

Cited by 34 publications

References 6 publications

Energy Savings Potential for Pumping Water in District Heating Stations

Energy Savings Potential for Pumping Water in District Heating Stations

Iso efficiency contours as a concept to characterize variable speed drive efficiency

Assessing variable speed pump efficiency in water distribution systems

Contact Info

Product

Resources

About