District Heating System Flexibility Studies Using Thermal Inertia of Buildings

Using combined heat and power plants (CHPP) is widespread in the Nordic countries, where district heating as a thermal load for CHPPs is typical for cities and towns. However, CHPP operation becomes more complicated at power market conditions. Errors in the forecasting of the temperature, which lies at the basis of CHPP operation mode planning (the difference between forecasted heat demand and the real one leads to a difference between planned and real electricity production), lead to an imbalance in electricity production in the day-ahead market. To improve CHPP profitability at power market conditions, different technologies are used to increase CHPP operation flexibility. The overall objective of this study is to evaluate, based on the example of the city of Riga, what possibilities of flexibility for each hour can be provided by the inertia of the heating system of Riga at possible temperature deviations from the comfort temperature.