Press Releases 2014

Today, we have started operation of Unit 4 of Kazunogawa Hydroelectric Power Station (maximum output: 400 MW).

Kazunogawa Hydroelectric Power Station is a pumped-storage hydroelectric power station utilizing an effective head (height difference between the upper and lower dam) of 714m^＊１, which generates 1,600 MW (400 MW per unit) of power at maximum output. Construction began in January 1993.
We were able to start operation of Unit 4 today, earlier than the originally planned schedule of 2020, by accelerating its construction with a view to securing power supply post the Great East Japan Earthquake. This is the third unit of the power station to start operation, following Unit 2, which started in June 2000.

For Unit 4, we employed a variable speed generator^＊２, which provides a major improvement in performance to maintain stable frequency, by adjusting the power on pumping up water to the upper dam for water reserve, as well as when running water down to the lower dam for generation.
The new generator runs at the prime rotational rate, which optimizes the effectiveness of the pump turbine and reduces vibration in order to enhance the generating efficiency.

With Units 1 and 2 having already started operation, we will operate all units of Kazunogawa Hydroelectric Power Station safely and steadily. And we will continue to fulfill our responsibility as a utility that ensures a stable and proper power supply.

*1 Effective head
The effective head of the water at Kazunogawa Hydroelectric Power Station is 714m, which ranks alongside the world’s highest level for a pumped-storage hydroelectric power station using one pump turbine for both pumping and power generation. This height was achieved by developing and adopting the “ultra high head pump turbine”.

*2 Variable speed generator
A generator that can adjust the rotation speed of a pump turbine when generating and pumping. It can modify frequency both on generating and on pumping, so is effective in maintaining the frequency to stabilize the electric power network system when unstable power, such as solar power or wind power, is supplied to the network.