Japan's Largest Wind Turbines Begin Operation With Batteries in Hokkaido
Power transmitted to grid as planned by charging, discharging batteries
Matsumaecho at the southernmost part of Hokkaido, Japan, faces the Sea of Japan to the west and Tsugaru Straits to the south, with towns and pastures spreading along the west-east coast for about 50km. Thanks to the Tsushima Current, the town enjoys the warmest and mildest climate of any town in Hokkaido and prospered as the castle-town of the Matsumae Domain.
With winds stably blowing at annual average speeds of 5 to 6m/s more than 30m off the ground, the town is also known as being suitable for wind farms, and multiple wind turbines have been operating in the town since around 2000.
As tall as 148m Sapporo TV Tower
In April 2019, the "ReENE Matsumae Wind Farm," Japan's largest-class wind farm with a total output of over 40MW, began operation in the town. A total of 12 wind turbines with a rated capacity of 3.4MW each rotate slowly thanks to the sea breeze. As of April 2019, the "3.4MW" was the largest capacity for a single unit among commercial wind turbines in operation across Japan. In addition, this is Hokkaido's first wind farm established with a storage battery system.
Matsumae Wind Farm GK, the power producer financed by Tokyu Land Corp and Japan Wind Development Co Ltd (Minato-ku, Tokyo), started commercial operation on April 3, 2019. The wind farm facilities' rated capacity totals 40.8MW, while the storage battery system's capacity reaches 18MW. Annual power generation is expected to amount to 105,900,000kWh, which is equivalent to the consumption of about 30,000 general households.
The wind farm facilities are produced by Siemens Gamesa Renewable Energy SA of Spain. The tower and the blade measure 94m in height and 54m in length, which results in a rotation diameter of 108m. When the blade comes up, the highest point reaches 148m, which is almost equivalent to the height of the TV tower in Odori Park, Sapporo City.
A sodium-sulfur (NAS) battery system of NGK Insulators Ltd and power conditioners (for the battery) of Toshiba Mitsubishi-Electric Industrial Systems Corp (TMEIC) were adopted (Fig. 1).
Elevator provided in tower
The completion ceremony and a tour of the ReENE Matsumae Wind Farm took place on May 30, 2019. After touring the power generation facilities by bus, a ritual was carried out at the shrine in Matsumae Park.
The wind farm facilities stand along Route 228 on the mountain side, with the grid substation facility and the storage battery system (electric power storage device) positioned at the southernmost area and the wind turbines from No. 1 to No. 12 scattered across the hills for about 15km northward from Tatehama District to Kiyobe District.
Among these facilities, we visited wind turbine No. 7 as well as the grid substation facility and the storage battery system. Wind turbine No. 7 is adjacent to one of the town's ranches where cows are pastured. The scene of the 54m blades' casting huge shadows on the grass field and slowly rotating is nothing but overwhelming (Fig. 2).
According to the plant, local elementary school children visited wind turbine No. 7 when it was under construction and drew pictures on the nacelle (cover to house a power generator and other items on top of the tower), which was lying on the ground before assembly. Now 94m above ground, however, these pictures can no longer be seen from the bottom of the tower (Fig. 3).
During the plant tour, the entrance at the bottom of the wind turbine tower was kept open for visitors. Inside the entrance door was a machinery room on the ground where power conditioners and boosters were housed. Electric power generated by the power generator in the nacelle above is transmitted to the bottom of the tower at 1,000V and boosted to 22,000V by the booster before being transmitted to the grid substation (Fig. 4).
When it comes to a large wind turbine of this class, climbing up the stairs from the bottom of the tower to the nacelle for each inspection and maintenance operation is a physical challenge. Given such circumstances, a small elevator is installed in the tower. The machinery room on the ground also functions as the platform for the elevator (Fig. 5).
Large wind farm facilities face a challenge when transporting them from the factory to the place to set them up. This time, the nacelle and the blades were transported from Denmark while the tower was transported in five pieces from Shanghai, China by ship and unloaded at the port of Esashi, Hokkaido. A 1,200t crane was reportedly used to assemble them.
2MW/unit NAS batteries used
The grid substation and the storage battery system were both set up in the same site. In addition, an administration building with a SCADA (supervisory control and data acquisition) room and an office was also constructed on-site.
Nine 2MW NAS batteries were installed. Power conditioners with a total output of 2MW control each battery's charging and discharging. Compared with normal power conditioners for solar power generation, which only convert direct current (DC) electricity from solar panels into alternate current (AC), power conditioners for storage batteries are, to control power charging and discharging, bidirectional-type that feature both functions to convert AC from wind turbines into DC and to convert DC from storage batteries into AC (Fig. 6 & 7).
The wind turbines and batteries are connected using the "AC link" method, in which output combining AC from wind turbines and AC from storage batteries is transmitted to the grid of Hokkaido Electric Power Co Inc (Hokuden). Smoothing short-term fluctuations on a second scale and long-term fluctuations on an hour scale by charging and discharging the batteries to make up for changes in the amount of wind power generation, the plant alleviates Hokuden's grid operation load.
To be more specific, the plant formulates and submits in advance a power generation plan (power transmission plan), in which output fluctuations are kept below a certain rate, to Hokuden and charges and discharges the batteries in accordance with the plan. There are displays for real-time monitoring of such battery operation in the SCADA room inside the administration building. This was also exhibited to visitors during the tour (Fig. 8).
Thoughts expressed by 3 'humans'
Tokyu Land is promoting a variety of developments as a comprehensive real estate developer, having started operating or constructing/developing 44 projects equivalent to 844MW thus far in the renewable energy business. Of the 44 projects and 844MW, solar, wind and biomass power generation account for 37 projects and 677MW, six projects and 118MW and one project and 50MW, respectively.
The company has approached renewable energy development focusing on solar power from immediately after the feed-in tariff (FIT) scheme was implemented. Unlike many leading companies in Japan, which have gradually been withdrawing from new developments as the FIT-based power selling unit price falls, since April 2016, Tokyu Land has advocated a business strategy to further strengthen renewable energy development.
The company also created the "ReENE >>>" logo for its renewable energy business and has used it to appeal both inside and outside the company. The power plant was named ReENE Matsumae Wind Farm in accordance with this business brand strategy. The ">>>" on the right of ReENE express three "humans" in Japanese (Fig. 9).
What the three "humans" represent are "local community," "society" and "environment," and Tokyu Land expressed its vision to support people who are striving to improve these three areas, allying and cooperating with them through the renewable energy business.
"Through our brand strategy for the renewable energy business, we are aiming to make this vision further penetrate both inside and outside our company," said Keisuke Nishida, executive manager of Infrastructure & Industry Business Department, Tokyu Land.
In April 2019, Tokyu Land joined the international initiative "RE100," which aims to secure energy for business activities 100% from renewable energy. However, the company is aiming not only for just boosting the renewable energy ratio, but also for "vitalizing the local community through the development and operation of renewable energy facilities" (Fig. 10).