Reducering av effekttoppar i Halmstads fjärrvärmesystem : Modellering av ett teoretiskt laststyrningsschema

On behalf of Halmstads Energi och Miljö (HEM) this paper investigates the possibilities to reduce power peaks in their district heating production through demand side management. The purpose with this paper is to reduce the power peaks with 10 MW and investigate which customers or areas HEM should focus on. In addition, two bottlenecks in the district heating network are analyzed by the effects of demand side management. A theoretical model of demand side management was constructed. The model uses hourly data from production and endeavor to daily average values. The model also included parameters such as storage capacity and manipulated outdoor temperature. The results from demand side management relates to the total daily variations of the district heating system. The demand side management has been applied to a selection of 214 substations and three independent demand side management schemes for the year of 2016, one for each bottleneck and one for the total 214 substations. The choice of substations for demand side management is based on which buildings are connected to them. Criteria for the selection are buildings with high thermal mass, which give high thermal inertia and buildings with high heat demand (large apartment buildings). It is of great interest to investigate how demand side management affects the indoor temperature in selected buildings because limit values cannot be exceeded. The result shows that the power peaks can be reduced by 11.7 MW (mean value) for the whole year excluding the months of spring and summer and for the winter months 13.1 MW (mean value). The reasons why the power peaks can be reduced to a greater extent during the winter months was due to a larger heat demand and heat load variations. Two bottleneck areas applied one theoretic demand side management scheme each where power peaks can be reduced by 0.63 MW(mean value) and 0.7 MW(mean value) excluding spring and summer months and 0.71 and 0.72 only including winter months. The profit from reducing the power peaks for HEM is shorter operating time for the peak heating boilers. The power peaks is later compensated and balanced with renewable bio energy. The simulation from 2016 brings a cost saving to 2.7 million SEK. The profit comprises the cost difference between fossil fuels, natural gas and renewable fuels such as wooden chips. The carbon dioxide reduction during the same period of time was 1671 metric tonne CO2- equivalents