Grid Impact Indicators for Active Building Simulations

This paper presents grid impact indicators, developed to evaluate the performance of local control mechanisms, affecting the impact of a net-zero energy building on the electricity grid, without the need to simulate the grid itself. The capacity factor, loss-of-load probability, cover factor for supply and demand, load match index, power exchange variability, one-percent peak power, peaks above limit, dimensioning rate, and kVA credit are proposed and applied to example single-building simulations. These simulations include control mechanisms affecting the power exchange of the building with the grid by adjusting the set-point temperature of the thermal energy storage tank of the heat pump, shifting local consumption to better coincide with local photovoltaic generation, or by directly limiting the power supplied to the grid. The simulations focus on a single net-zero energy building and use one such building as a reference and others for comparison of trends in simulation results. All modeling is done in the equation-based object-oriented modeling language Modelica. Simulations are performed using the Dymola environment.