The main themes of our research group are demand response, resilient power system and real time stability monitoring of power systems. The summaries of the themes are as follows.

The first theme is fast demand response to assist frequency control. The increase of renewable energy generation such as PV and wind power tends to cause imbalance between generation and load according to the intermittency of the generation. In addition, it results in the decreasing of operated thermal generation units which can provide spinning reserve, so that frequency deviation becomes large. In order to avoid the shortage of spinning reserve, we propose an application of fast demand response with a lot of heat pump air conditioning systems owned by electricity consumers. Fig. 1 shows a configuration of real time simulator with actual geothermal heat pump systems to evaluate effectiveness of the fast demand response.

The second theme is a resilient power system. After large disaster such as earth quake and tsunami, large power plants and main transmission systems will be damaged, so that many people will suffer from blackout during several days. In order to avoid such blackout, we propose a power supply system with undamaged distribution feeders and distribution generation such as PV and EV. Fig. 2 shows the concept of such power supply system.

The third theme is development of real time stability assessment of large electric power systems by monitoring power flow fluctuations on the major transmission lines. The power flow fluctuations can be measured and collected to a control center by using a GPS based data acquisition system. The main purpose of this research is to develop methods for evaluating damping power for weakly damped oscillations in real time.

Fig. 1 Real time simulator for fast demand response

Fig. 2 Emergency operation of Islanded Distribution Networks