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Laboratory tests of HVAC systems providing power grid ancillary services.

Number: pap. 3590

Author(s) : CAI J., BRAUN J. E.

Summary

Real-time power supply and demand balances are critical to ensure stable power frequency and quality power services. However, the growing integration of renewable energy increasingly challenges the power infrastructure because most of the renewable resources, e.g., solar and wind energy, are intermittent and difficult to predict. To meet the stringent power frequency requirements, more fast reacting frequency regulation resources are being brought online among which grid-level batteries are the dominant ones. Although batteries can provide fast and high quality regulation services, they suffer from high initial cost, high environmental impact and round-trip efficiency losses. When providing fast frequency regulation services, battery life span could be significantly reduced, leading to even higher cost per unit of frequency regulation service. Buildings consume more than 73% of the electricity in the US, offering significant regulation reserve for the power grid. Variable-speed air-conditioning systems are taking an increasing share of the market due to the higher efficiency requirements imposed by federal agencies. In addition to efficiency benefits, variable-speed cooling/heating systems are also perfectly suited for providing ancillary service as these units can modulate their power continuously over a wide range. Compared to batteries, HVAC systems have several advantages for frequency regulation: 1) in theory, they do not incur any round-trip efficiency loss; 2) the time response of an AC unit could be faster than a battery (especially compared to energy batteries with slower ramping rates and relatively larger capacities); 3) the existing regulation capacity of HVAC systems is significant and the implementation cost is marginal compared to installing grid-level batteries; 4) HVAC systems have smaller embodied carbon compared to batteries. This paper presents laboratory test results of a variable-speed heat pump for power frequency regulation. Regulation performances for both the traditional (slow) and dynamic (fast) regulation services are reported. The tested performance scores were above 0.97; the regulation performance even beats the average regulation performance of batteries. Preliminary economic analysis was also performed using historical wholesale electricity and regulation prices. The results show that the credit received for frequency regulation could offset up to 47% of the HVAC electricity cost under the tested conditions.

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Pages: 10

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Details

  • Original title: Laboratory tests of HVAC systems providing power grid ancillary services.
  • Record ID : 30024908
  • Languages: English
  • Source: 2018 Purdue Conferences. 17th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2018/07/09

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