The influence of simulation time-resolution on the matching between on-site micro-wind generation and building electric demand

Abstract

This paper is to investigate the unique impact of simulation time-resolutions on energy matching between on-site micro-wind turbine and household electric demand. The focused indices are on-site electrical energy fraction (OEFe), on-site electrical energy matching (OEMe), and their errors (e_OEF and e_OEM). The methodology consists of parametric analyses with respect to time-resolution levels, averaging methods, demand profiles, turbine capacities, and wind conditions. Two averaging methods are used: ‘Speed Averaging’ and ‘Power Averaging’. With a coarser resolution, two averaging effects have been found. One is an overestimation effect by both the averaging methods, which are more likely to be encountered especially when a high-resolution generation curve frequently crosses intermittent long spikes of a demand curve. The other effect is an underestimation effect on OEFe simultaneously occurring with the Speed Averaging Method under the conditions of (1) a low wind speed and (2) a high unstable wind speed and a low turbine capacity.

Keywords:

• simulation time-resolution
• time-step
• energy matching
• energy mismatch
• building simulation
• micro-wind turbine

Acknowledgements

Mr Kristian Bäckström from Posintra Oy is greatly acknowledged for providing us the high-resolution monitored electrical demand data.

Nomenclature

Δt	=	time-step used in the research
ED	=	electrical demand
eOEF	=	the errors of OEFe caused by coarser resolutions when compared to the finest resolution of 1 min (%)
eOEM	=	the errors of OEMe caused by coarser resolutions when compared to the finest resolution of 1 min (%)
G	=	on-site generated power (kW)
Gelec	=	electrical power generated by the on-site electrical energy production system (kW)
hr	=	hour
L	=	load power (kW)
le	=	electrical loss of on-site electrical power during distribution process (kW)
Lelec	=	electrical load power (kW)
OEF	=	on-site energy fraction
OEFe	=	on-site electrical energy fraction
OEM	=	on-site energy matching
OEMe	=	on-site electrical energy matching
PV	=	photovoltaic
t1	=	starting point of the time span
t2	=	end point of the time span

Additional information

Funding

This work was financially supported by the Academy of Finland under the Grant for the Consortium Project ‘Advanced Energy Matching for Zero-Energy Buildings in Future Smart Hybrid Networks’. The high-resolution weather station is financially supported by Aalto University as part of the infrastructure support for the HVAC laboratory in the Department of Energy Technology. Moreover, the TEKES RYM-SY and the Aalto University SAGA projects are greatly acknowledged for partly supporting this research.