Abstracts Physics

Economic Analysis of a Data Center Virtual Power Plant Participating in Demand Response

by Labi Bajracharya

Data centers consume a significant amount of energy from the grid, and the number of data centers are increasing at a high rate. As the amount of demand on the transmission system increases, network congestion reduces the economic efficiency of the grid and begins to risk failure. Data centers have underutilized energy resources, such as backup generators and battery storage, which can be used for demand response (DR) to benefit both the electric power system and the data center. Therefore, data center energy resources, including renewable energy, are aggregated and controlled using an energy management system (EMS) to operate as a virtual power plant (VPP). The data center as a VPP participates in a day-ahead DR program to relieve network congestion and improve market efficiency. Data centers mostly use lead-acid batteries for energy reserve in Uninterruptible Power Supply (UPS) systems that ride through power fluctuations and short term power outages. These batteries are sized according to the power requirement of the data center and the backup power duration required for reliable operation of the data center. Most of the time, these batteries remain on float charge, with seldom charging and discharging cycles. Batteries have a limited float life, where at the end of the float life, the battery is assumed dead, and require replacement. Therefore, the unused energy of the battery can be utilized by allocating a daily energy budget limit without affecting the overall float life of the battery used in data center for the purpose of DR. This is incorporated as a soft constraint in the EMS model, and the extra use of battery energy over the daily budget limit will account for the wear cost of the battery. A case study is conducted in which the data center is placed on a modified version of the IEEE 30-bus test system to evaluate the potential economic savings by participating in the DR program, coordinated by the Independent System Operator (ISO). We show that the savings of the data center operating as a VPP and participating in the DR program far outweighs the additional expense due to operating its own generators and batteries. Advisors/Committee Members: Timothy M Hansen.