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1. Architecture for demand responsive HVAC in a commercial building for transformer lifetime improvement.

Author

Teja S, Charan and Yemula, Pradeep Kumar

Subjects
*AIR conditioning, *COMMERCIAL buildings, *VENTILATION, *HEATING & ventilation industry, *POWER resources, *ALGORITHMS
Abstract

• Bringing the asset management of transformer under the purview of building manager from utility. • Derived mathematical model of demand response from transformer thermal model. • Method to estimate transformer temperature time constant from measurements and algorithm for improving the life of transformer by regulating HVAC and AHUs. • Smart grid architecture for demand responsive HVAC. • Real time simulation of impact of demand response using the actual building consumption data from an academic campus. Overloading and ageing effects contribute to 12-15% of distribution transformer failures in India. This research is motivated in extending life of transformer by using demand response as an operational strategy where the demand response events are issued by predicting overheating of transformer before it occurs. In this paper heating ventilation and air conditioning is considered as a flexible load for responding to demand response events. A demo site is created at 11 KV/440 V substation with 1.6 MVA transformer at Indian Institute of Technology Hyderabad (IITH) campus and the proposed architecture and algorithm is implemented. This substation supplies power to chiller plant and three academic buildings with heating ventilation and air conditioning (HVAC). Analysis for improving the transformer lifetime is carried out for 5 consecutive days during the period (25–29)th Feb 2020 using real time field data. It is observed that during this period 11 demand response events occurred with a total demand response of 919 kWH. From the obtained results it is observed that there is a saving of 15 hoursof transformer life within a period of 5 days (120 hours) of transformer operation. The key contribution in this paper is to bring together three concepts transformer lifetime estimation, HVAC flexibility and demand response for improving the transformer lifetime. [ABSTRACT FROM AUTHOR]

Published
2020
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2. Assessment of Demand Limiting Using Building Thermal Mass in Small Commercial Buildings.

Author

Braun, James E. and Kyoung-Ho Lee

Subjects
*ALGORITHMS, *COMMERCIAL buildings, *VENTILATION, *HEATING, *AIR conditioning, *TEMPERATURE, *OPERATING costs, *HEATING & ventilation industry
Abstract

This paper describes the development and evaluation of a simple algorithm for limiting peak electrical demand in buildings using building thermal mass. The control algorithm is intended to reduce electrical demand in response to utility critical peak pricing (CPP) signals or similar incentives and involves adjustment of zone temperature setpoints within comfort bounds. The demand-limiting potential and impact on utility costs for CPP rates were evaluated through simulation for representative small commercial buildings throughout California. In general, it is possible to achieve between 1 and 2 W/ft² (10.76 and 21.53 W/m²) of demand reduction for a four-hour demand-limiting period while keeping zone temperatures between 70°F and 78°F (21.1°C and 25.6°C). This represents a 30%–100% reduction in peak electrical requirements for air conditioning depending on the climate. For typical CPP utility rates, the impact of the demand-limiting strategy on operating costs is relatively small, with less than about $50 in annual savings per 1000 ft² (92.9 m²). Greater incentives may be necessary to encourage customers to respond to critical capacity shortages. Furthermore, CPP super-peak energy rates do not encourage customers to minimize their demand during CPP periods but, rather, encourage them to reduce their integrated energy usage over this period. A better incentive would involve imposing a high peak demand charge for CPP periods. [ABSTRACT FROM AUTHOR]

Published
2006