ABSTRACT
Heating, ventilation and air conditioning (HVAC) systems play an essential role in demand response (DR) programs. In this paper, a fuzzy controller is designed to adjust the HVAC set-points optimally. The aims of the designed controller are multifold: to save energy, to improve user’s comfort, and reduce HVAC electricity costs. In the current research, indices such as daily energy cost, minimum and maximum home temperature, energy usage, energy usage during peak hours, and user’s comfort are proposed and discussed for the evaluation of HVAC function. In addition, the effect of different pricing schemes such as fixed pricing (FP), time-of-use pricing (TOU), and real-time pricing (RTP), are analyzed. Further, the adaptability of the proposed model enabled us to investigate users with different attitudes toward welfare and cost. Finally, the effects of set-point and dead-band width are discussed. The results show that the proposed controller reaches the pre-determined aims successfully.
Abbreviations: HVAC: Heating, ventilation, and air conditioning; FP: Fixed Pricing; TOU: Time Of Use; RTP: Real Time Pricing; PR: The HVAC system energy consumption cost in a day; UC: The total time that the user experiences an uncomfortable situation in a day; T_min: The minimum RealFeel Temperature experienced in a day by the user; T_max: The maximum RealFeel Temperature experienced in a day by the user; ECP: Energy consumed by the HVAC system during peak hours; EC: Energy consumed by the HVAC system during a day
Nomenclature
θ(k) | = | load internal temperature at the kth time step |
θa | = | Ambient temperature |
Ε | = | White noise |
C | = | Thermal load capacity |
R | = | Thermal resistor |
H | = | Simulation step time |
θg | = | Thermal gain |
Ptrans | = | mechanical power transferred to the environment |
COP | = | Thermal transaction cofactor |
RUi | = | Fuzzy rule number i |
Tout fuzzy | = | Controller output Temperature |
Tambient | = | Ambient Temperature |
Tdesired | = | User’s desired Temperature |
Δ | = | Dead-band width |
Σ | = | Standard deviation of price at Tmin and Tmax |
Paverage | = | Average price in 24-hour window |
A | = | Fuzzy variables |
B | = | Fuzzy variables |
N | = | Number of fuzzy rules |
C* | = | output crisp value |
Ci | = | Fuzzy Sets |
wi | = | Firing strength |
μinput1i | = | input1 membership grade |
μinput2i | = | Input 2 membership grade |
μinput3i | = | Input 2 membership grade |
xi | = | Fuzzy inputs |
Tadjusted | = | Mathematical Controller output temperature |
Tmin | = | Minimum allowed temperature in the mathematical controller |
Tmax | = | Maximum allowed temperature in the mathematical controller |
Khigh | = | Standard deviations between Tdesired and Tmax |
Klow | = | Standard deviations between Tdesired and Tmin |
Pcleared | = | Cleared market price |