Special

What is TMEIC's '3rd-Generation PV Inverter'? (2) (page 3)

With advantages of both central-, string-type PV inverters

2019/08/24 19:01
Kenji Kaneko, Nikkei BP Intelligence Group, CleanTech Labo
Print Page

Differentiation by 'integrated control'

TMEIC also plans to showcase the functions that cannot be realized by string-type units, in addition to introducing the "modular system," for differentiation. The company plans to use an integrated control system called the Main Site Controller (MSC) in combination.

The "integration" in this case means integration of multiple PV inverters for control. The MSC is an overall control system in the upstream process of each PV inverter.

Requirements of PV inverters will continue to increase in the future responding to introduction of solar power in large amounts. Reduction of load on power grids, satisfying the requirements for grid connection for stabilization of grid operation in the daytime when the demand for power is low, as well as output control by power companies, will be common in the future. Responding to these complicated requirements on control will be possible by introducing the MSC, according to the company.

It is also estimated that reduction of output fluctuations in "short cycles" of seconds and "long cycles" of hours by combined use of storage battery systems will be set as conditions for grid connection of renewable energies including solar power and wind power with output fluctuations in the future.

If the MSC is used, integrated control including PV inverters for storage batteries will be possible, also making it easy to equalize the renewable energy output in short cycles and long cycles.

Storage batteries are already used in combination with solar power plants in isolated islands, household power generation systems and so forth in Japan, and the company commercialized the TMBCS (TMEIC Battery Control System) for this purpose. In the TMBCS, the MSC is controlled in linkage with PV inverters for storage batteries and monitors the power generation amount of each grid connection point throughout the site in real time, controlling the batteries for charge and discharge (Fig. 6).

Fig. 6: "TMBCS (TMEIC Battery Control System)" introduced to a mega solar power plant equipped with storage batteries on Tokunoshima Island (source: Nikkei BP)

TMEIC expects that the combination of the "modular system" PV inverters and the MSC will contribute to the reduction of initial investments by power producers, as well as to operation power saving and improvement of income, responding to the needs of the time when renewable energies are introduced in large amounts.