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Kinden Sets Up 1MWh NAS Battery, PV System at Its Building (2)

BCP measures, peak shift adjustment tested

2016/09/26 03:45
Kenji Kaneko, Nikkei BP CleanTech Institute
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Continued from Kinden Sets Up 1MWh NAS Battery, PV System at Its Building (1)

Charged in nighttime, discharged in daytime

The headquarters building was conventionally equipped with a solar power generation system of several kilowatts. And, this time, a new system featuring 30kW of output was installed on the rooftop (Fig. 4). All of the power will be consumed inside the company without selling any under the FIT scheme. The solar panels are the products of Sharp Corp.

Fig. 4 Solar panels of 30kW output installed on the rooftop of the Kinden headquarters building (Source: Kinden)

The storage battery and the solar power generation system were separately connected to the AC 400V system in the headquarters building. In discharging from the NAS battery, the DC 200V output is converted to AC 400V by a bidirectional power conditioner exclusive for the storage battery for connection. On the other hand, in charging the battery, AC 400V is converted to DC 200V by the power conditioner for connection. The DC power from the solar batteries is converted to AC 400V by a PV inverter for connection.

The power conditioner for the storage battery was manufactured by Nissindenso Corp and the PV inverter for solar panels was manufactured by Yaskawa Electric Corp.

The equipment is used for consumption of nighttime power as peak shift measures during ordinary times while it is used as an emergency power supply to ensure BCP during disasters.

Peak shift is basically controlled according to a schedule where the battery is charged at nighttime and discharged in the daytime. The peak demand of the Kinden headquarters building is 600-700kW. The company is trying to decrease the peak demand to 400-500kW by working out an appropriate operation method, such as reducing the power reception by 50 to 100kW through discharge in the daytime. The actual peak demand is in winter. And if the contract demand can be lowered after a test operation throughout one year, the electrical charge will be lowered.

The 30kW solar power generation system outputs 22 to 24kW of power on clear days. The headquarters building requires about 100kW of power in the daytime even on weekends. The total amount of power generated by the system can be consumed internally instead of being sold. Therefore, the company incorporated a system in which the generated power is not exported back to the grid of Kansai Electric Power Co Inc.