Demonstration projects for providing ancillary services using three different types of large-scale battery systems

摘要

The penetration of wind and photovoltaic generation has brought system operators concern about electrical power quality such as frequency due to the increase in difficulty of regulating supply-demand balance. Application of a battery system is expected to become one of the countermeasures against problems like shortage of downward regulation reserve or frequency fluctuation in relatively small-scale power systems. In Japan, large-scale battery systems using three different types of storage batteries were installed between 2015 and 2016 in four sites, and the verification of countermeasures against frequency fluctuation, surplus power, etc. has been implemented. At the site in Hokkaido area, a Vanadium Redox Flow battery has been adopted due to its ability to independently and flexibly design ratings of output power (kW) and energy (kWh) for multiple verification categories (frequency fluctuation and surplus power). The verification of short-period (high frequency) fluctuation mitigation control (governor free equivalent control, load frequency control, etc.), long-period (low frequency) fluctuation mitigation control, and hybrid control (combination of plural controls) has been in progress. At two sites in Tohoku area, Lithium Ion batteries have been adopted due to their quick and efficient charge and discharge ability. At one site, the frequency control logic of the battery control system was evaluated as a countermeasure against frequency fluctuation and the battery system operation was verified. At the other site, the improvement of flexibility for downward regulation reserve was verified as a countermeasure against surplus power by using the charge and discharge of the battery system. Furthermore, the voltage fluctuation mitigating effect was verified by using the reactive power control function of the battery system. At the site in Kyushu area, a Sodium-Sulfur (NaS) battery has been adopted and the reasons for the adoption are that its cost per capacity is superior to other kinds of batteries and it is expected to become one of the effective countermeasures against surplus power. In the charge-discharge test for the improvement of supply-demand balance, it was confirmed that the battery system could charge and discharge as planned to avoid curtailment of renewable energy. The system voltage control test, which took advantage of reactive power output of the battery system, proved that the battery system could be used in place of a capacitor or shunt reactor. These demonstration projects will contribute to the application of a large-scale battery system as one of the new methods for providing ancillary services against the high penetration of renewable energy sources.