Doctoral Thesis: Active Power Ancillary Service Provision of Commercial Building Energy Storage Resources

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Event Speaker: 

Youngjin Kim

Event Location: 

Grier A, 34-401A

Event Date/Time: 

Thursday, August 13, 2015 - 2:00pm

Abstract
 
The aim of this thesis is to design an alternative configuration
of commercial building power systems, propose new control strategies of
building energy storage units, and analyze their effects on power grids and
electricity markets. Specifically, in the research, the input power control
methods of plug-in electric vehicles (PEVs) and variable speed heat pumps
(VSHPs) were proposed to improve real-time grid frequency regulation (GFR)
and day-ahead (DA) electricity market clearing. The feasibility and
effectiveness of the proposed control methods were then evaluated using
small-signal analysis, simulation case studies, and experimental
verifications.

Energy storage resources (ESR) have been widely utilized to mitigate
variations in the output power of renewable energy sources (RES). This
research proposes a new GFR method using PEVs and VSHPs, which compensate
for the high- and low-frequency components of load demand variations in
power grids by responding to direct load control (DLC) signals given from
grid operators. To investigate the PEV contribution to the improvement of
GFR, a small-signal analysis was carried out using transfer functions that
represented the aggregated dynamic responses of generators and DLC-enabled
PEVs. In the analysis, the closed-loop properties of the proposed GFR scheme
were comprehensively analyzed using Bode and pole-zero plots. In addition, a
dynamic model of a VSHP was presented to assess the effects of the
DLC-enabled VSHPs to the GFR. The model was simplified for real-time
simulation studies with the time horizon ranging from seconds to hours, but
still sufficiently comprehensive to analyze the operational characteristics
such as the heat rate and coefficient of performance. A dynamic model of an
MIT experimental room was then developed to estimate the effect of the DLC
application to the VSHP on indoor air temperature for two different cooling
systems: convection cooling and thermally activated building system (TABS)
cooling methods. Small signal analysis was also performed to evaluate both
the transient response of the DLC-enabled VSHP and its contribution to GFR,
especially with respect to variations in the VSHP penetration. Corresponding
building-side and grid-side simulation case studies were performed using
Matlab/Simulink. The proposed GFR method was experimentally implemented
using a laboratory-scale test microgrid that consisted of a
converter-interfaced battery pack, as well as generator and load emulators.

Microgrid control centers were developed using C and Matlab/Simulink, which
communicated with the individual hardware units to provide the real-time GFR
ancillary service. The small-signal analysis, simulation case studies, and
experimental implementation consistently demonstrated the advantages of the
proposed GFR scheme, which were achieved with small variations in the
building room temperature and the battery SOC.
 
Thesis Supervisors: James L. Kirtley, Leslie K. Norford