1 The 50th IEEE PES T&D Conference and Exposition
Variable Speed Heat Pump (VSHP) Design for
Frequency Regulation through Direct Load Control
Authors: Young-Jin Kim (MIT EECS, [email protected]),
Prof. Leslie K. Norford, and Prof. James L. Kirtley Jr.
04.17.2014
2 Jin ( MIT EECS, [email protected] )
(a) No. of High Frequency Excursion Events (b) No. of Low Frequency Excursion Events
Frequency excursion ( f > 60.05 Hz ) or ( f < 59.95 Hz ) due to load variations
1. Introduction : Real-time Frequency Regulation
Grid-connected energy storage resources
: PHEVs (electrical), flywheels (mechanical), or water heaters (thermal)
3 Jin ( MIT EECS, [email protected] )
2. Direct Load Control (DLC)-enabled Variable Speed Heat Pump
DLC-enabled VSHPs: thermal energy storage for grid frequency regulation
5
2-1. Modeling of Variable Speed Heat Pump
Jin ( MIT EECS, [email protected] )
Steady-state response characteristics of VSHP
(a) Mech. Power and Motor Speed (b) COP and Heat Rate
6
2-1. Modeling of Variable Speed Heat Pump
Jin ( MIT EECS, [email protected] )
Transient response characteristics of VSHP
(a) Mech. Power and Motor Speed (b) Mech. Power and Temperature
7
2-2. Modeling of Variable Speed Drive (VSD)
Jin ( MIT EECS, [email protected] )
Step response of VSD-controlled VSHP to ΔPref = 10 W
(a) Input Power
Variation
(b) Shaft Speed
Variation
8 Jin ( MIT EECS, [email protected] )
2-3. Modeling of Building Room
Experimental building room consisting of test and climate chambers
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(a)
2-3. Modeling of Building Room
Jin ( MIT EECS, [email protected] )
Thermal networks using analogy between thermal and electrical systems
(b)
10
(a) Heat Pump Power Consumption in Boston Univ. Test Building
(c) Direct load control signals 10/24
3. Case Studies and Simulation Results
Jin ( MIT EECS, [email protected] )
Commercial building with VSHPs in response to DLC signals
(b) Direct Load Control (DLC)
Signals for VSHP Models
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- Generators (DGs) : S = 25 MVA, Building: S = 0.7 MVA with 25-kW VSHPs
11/24
3. Case Studies and Simulation Results
Jin ( MIT EECS, [email protected] )
Isolated microgrid with commercial buildings
12 Jin ( MIT EECS, [email protected] )
3-1. Grid Frequency Regulation Scheme for DLC-enabled VSHPs
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3-2. Simulation Results of VSHPs
Jin ( MIT EECS, [email protected] )
(a) Input Power Variations (b) Shaft Speed Variations
Adjustment of VSHP power/speed in response to DLC signals
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3-2. Simulation Results of VSHPs
Jin ( MIT EECS, [email protected] )
VSHPs Operations PHP [kW] QHP [kW] COP
ωT_ref1 DLC-enabled 15.04 68.72 5.62
Conventional 15.07 68.81 5.60
|Diff.| [%] 0.20 0.13 0.36
ωT_ref2 DLC-enabled 17.48 75.96 5.20
Conventional 17.55 76.17 5.18
|Diff.| [%] 0.40 0.28 0.39
5-hour average performance of DLC-enabled VSHPs
15 Jin ( MIT EECS, [email protected] )
3-3. Simulation Results of Building Rooms
Indoor temperature variations for cooling methods
16 Jin ( MIT EECS, [email protected] )
3-4. Simulation Results of Microgrid
Improvement of real-time grid frequency regulation
(a) Grid Frequency Deviations (b) DG Output Power Variations
17 Jin ( MIT EECS, [email protected] )
4. Conclusion
DLC-enabled VSHPs as thermal energy storage resources
1) Objective
- Frequency regulation ancillary service via the input power control of the VSHPs
- Ensuring both building occupant comfort and long-term device performance
2) Device Modeling and Simulation Studies
- Heat pump dynamic model that is simplified for real-time simulation studies,
but still comprehensive to analyze operational characteristics
- Test room model using two different cooling methods based on experimental setup
- Simulation case studies to demonstrate the effectiveness of DLC-enabled VSHPs