Quantifying flexibility for smart grid services

Renewable energy sources and other types of distributed generation are becoming ever more present in todays power supply mix. In addition, a change in electric load is being seen with the increase in electric heating and electric vehicles. These additions may create a number of challenges in the current electrical grid. At DSO level problems in substation congestion and voltage and frequency instability can be seen, as well at TSO level imbalances due to fluctuations in supply (e.g. wind power). One way of handling these added complexities is to utilize the flexibility in consumption and production that is available in the power grid. There are many types of currently unused flexibility. In this paper we consider one of the largest types of available flexibility with small devices at the distribution level, the thermal buffer in combination with electric heat pumps or combined heat and power units. A major obstacle in utilizing such flexibility is the inability to estimate at the DSO or TSO level the amount of power which can be ramped up and down as well as how long it can be sustained. In this paper we demonstrate how these characteristics can be estimated by creating quantifying formulas. Further, we validate these equations with a number of scenarios using thermal electric devices which are modeled based on currently installed, real world installations. These characteristics indeed can be accurately estimated given that some specifics of the systems available are known. Finally we discuss the benefits to different stakeholders of such knowledge.