2. Principle and performance of the W2P
The principle of the integrated generation is shown in Fig. 1. The
wind wheels, the oscillating bodies and the absorption mechanisms
collect and deliver wind power and wave energy, and convert them into
mechanical energy. The energy converters transform mechanical energy
into hydraulic energy which is stored in accumulators. The
hydraulic energy is transformed into electrical energy through the
hydraulic motors and electrical generators. Then the wind-wave power
plant established by the principle can provide power for the residential
electricity, the mining equipment, the hydrogen production, the sea
water desalinization and so on.
Based on the principle of the integrated generation, the high-power
W2P is proposed (Fig. 2a). The W2P consists of one large floating
platform, one WTG, three WECs and a set of generating equipment
including several groups of accumulators, hydraulic motors and
electrical generators.
The wind wheel with retractable blades (Fig. 2b) collect the
irregular wind power, which can adapt to a wide range of wind speeds
and withstand extreme wind conditions because of using the retractable
blades. The 3-DOF mechanism with the hemispherical oscillating
body (Fig. 2d) is used to collect the irregular wave power efficiently,
which can decouple the three motions (heave, roll and pitch) of the
oscillating body. The ECDs (Fig. 2c and e) are utilized to convert
mechanical energy from both the wind wheel and the mechanisms into
the same hydraulic energy. Finally, the stable hydraulic energy stored
in accumulators is used to drive the hydraulic motors and electrical
generators to produce electricity (Fig. 2f). The W2P has some
characteristics (2E3S):
(1) Enhanced power export. The unit can increase the energy yield per
unit area of seas. The W2P can be grouped to realize great power
output.
(2) Efficient power yield. The wind wheel can adjust the diameter and
the velocity according to the wind speeds to achieve the maximum
power coefficient. The 3-DOF mechanism can extract mechanical
energy from three motions of oscillating bodies.
(3) Smoothed power output. The wave resource is more predictable
and less variable than the wind resource. Some generators can be
shut off to achieve the optimal rotational speed when the incoming
wind power and wave energy decrease. The accumulators are used
to keep the oil pressure stable and store hydraulic energy.
(4) Simplified installations and maintenances. The generators of the
WTG are placed on the floating platform. The same ECDs are
adopted in the energy conversion, which simplifies the system
composition. The shared use of these installations and technicians
will reduce the cost.
(5) Strengthened reliability. In terrible weather conditions, the blades
of the wind wheel can shrink to the minimum length to protect the
WTG. Only the oscillating body of the WEC contacts with sea
water, which can reduce the corrosion.