Management of Distributed Generation for Smart Buildings

Abstract

Small and modular Distributed Generation (DG), such as fuel cells, can be used for onsite service within smart buildings to cover a part of the electrical and thermal load demand. In this case, the optimal capacity and output from the used generating unit(s) can be calculated to supply a part of load demand, where the excess/lack of power is exported to/imported from the utility. Minimization of the energy price is a main target in this case to achieve win–win situation and to enable DG units to participate as a source of power with the utility. This can be achieved by the optimal management of the daily performance of the candidate DG unit(s), such as proton exchange membrane (PEM) fuel cells located in smart buildings. The process could be developed to include multi-DG units in the building in a cooperative manner. The simultaneous generation of electrical and thermal energy has to consider the load requirements in an economic framework. Smart meters are required to account for the surplus/shortage energy that is exported to/imported from the utility, respectively. The main challenge when using such units in residential applications is their high cost. Therefore, the management process depends on an accurate economic model to describe all operating costs considering both electrical and thermal relations. Due to the discontinuity and nonlinearity of the model, a robust optimization tool has to be utilized.

Appendices

Appendix A

The following Table gives the Fuel cell parameters used in the economic model of a single unit.

	Value	Unit
KO&M	0.005	$/kWh
MST	1.5	h
MRT	1.5	h
Nmax	4.0	–
Pa	0.2	kW
Pmax	4.0	kW
Pmin	0.2	kW
αh	0.05	$
β	0.15	$
∆PU	8.0	kW/h
∆PD	10.0	kW/h
τ	0.75	h

The relationship linking FC efficiency with the produced electrical power is given as follows:

$$h_J = 0.4485 - 0.0536\;P_J + 0.0127\;P_J^2 - 0.001824\;P_J^3 .$$

The relationship linking Fc thermal power with the produced electrical power is given as follows:

$$P_{{\text{th}},J} = - 0.0714 + 1.152\;P_J - 0.0237\;P_J^2 + 0.0443\;P_J^3 - 0.00373\;P_J^4$$

Appendix B

Fuel cells parameters used in t economic model of three units

The parameters are the same for the three units assuming that they are identical.

	Value	Unit
$K_{O\& M}$	0.005	$/kWh
MDT	1.5	h
MUT	1.5	h
Nmax	4.0	–
Pa	0.08	kW
Pmax	1.35	kW
Pmin	0.1	kW
αh	0.02	$
β	0.06	$
∆PU	4.0	kW/h
∆PD	5.0	kW/h
τ	0.5	h

The relationship linking FC efficiency with the produced electrical power is given as follows:

$$ \eta_J = 0.448 - 0.1608\;P_J + 0.114\;P_J^2 - 0.049073\;P_J^3 $$

The relationship linking FC thermal power with the produced electrical power is given as follows:

$$ P_{{\text{th}},J} = - 0.02073 + 1.05\;P_J - 0.0617\;P_J^2 + 0.341\;P_J^3 - 0.08754P_J^4 $$