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3. (a)
(i) Pneumatic
(ii) Hydraulic linkage
(iii) Mechanical linkage
(iv) Hydraulic Linkage
(v) Direct drive

3. (b) image
Archimedes - linear generator (directly connected to grid)
Pelamis - DFIG (AC/DC/AC conversion to grid)

3. (c)
Underwater cables
+ does not disrupt scenery
- high maintenance cost and risk

Above water cable
-pros and cons opposite of underwater cable

3. (d)
Energy generated
= 500kW*0.4*8760hours
=1752MWh
nHouses
=1752MWh/4377kWh
=400houses

3. (e) P = 1/2 pAv^3
1MW marine current turbine:
2knots = 2*1.85*1000/(60*60)
2knots = 1.0278 m/s

A = 1*10^6 / (0.5*1020*1.0278^3)
A = 1806 m^2
πr^2 = 1806
d = 2*r = 48m

1MW wind turbine:
A = 1*10^6 / (0.5*1.2*15^e)
A = 493.8 m^2
d = 2*r = 25m

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PV Array
- Converts solar energy to electrical energy (DC)
DC Load
- Draws DC power from the PV array
(The DC load determines the operating point)

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Part 1:

The General advantages:
– Clean source of energy
– Globally available
– One of the lowest priced RE technologies
– Application in urban and rural environments.

The General disadvantages:
– Has to compete with conventional on a cost basis
– Remote locations for the best sites
– Issues relating to noise and effective “condition monitoring”
– Wind is intermittent, akin to many RE resources.

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4. (a)
Ocean Wave Power
- Generally island communities have fuel energy imported at considerable cost. OWE conversion is very attractive when the minimum sea state condition required around the island facilities energy conversion.
- Peninsular Malaysia and East Malaysia is surrounded by ocean at multiple sides.
- They do not require any external fuel and do not cause any pollution.
- Relatively inexpensive to build as it only affects a small area.

OffShore Wind Power
- Only possible to harvest during monsoon season (November to March) as wind wave direction from north-east of Malaysia is predominant and monsoon season (May to September) as wind wave direction from south-west is predominant.
- Wind wave energies swell in their respective areas during these 2 seasons.
- Would be cost-inefficient if building a wind power generation system as there are only 2 high wind seasons in Malaysia.

4. (b)
Ocean Wave Power
- Structures have to withstand harsh and adverse environment specific to the nature of the sea.
Solution reliable design with tried and test components, safety mechanisms in storms can involve sinking the structure
- Peak power is generally available in deep sea far from land.
Optimise ocean topography nearer land and/or reliable design in deep sea with minimal complexity
- Wave frequency 0.1Hz is difficult to couple to generator frequency 50Hz. Solution is coupling

OffShore Wind Power
-Depending on the height of the wind tower,  high windspeeds may damage the turbine blades.
- That can be solved through active pitch control and stall control and also aids in maximizing output for all winds.

4. (c)
Ocean Wave Power
- Wave power conversion has been demonstrated technically but not economically.
- Significant resource but has been one of the last to be developed.
- Important criteria is simplicity and reliability, technically complex plants lacking well-proven technology are fundamentally untenable for OWC projects.

OffShore Wind Power
- Very stable and still growing in overseas but not in Malaysia.

4. (d)
Ocean Wave Power
- Large capital costs of the structures involved
- Can be installed in groups rather than singularly
- Clusters offer a better proposition than individual units because of maintenance, installation and operating costs are then spread over a much larger total generating capacity.

OffShore Wind Power
- Large start-up costs for manufacturing, setting up and shipping rotor blades and building up a wind tower.
- Maintenance cost will be very high as it is very difficult to work around offshore and high towers.
- Requires a very long time to return on investment.

4. (e)
Ocean Wave Power
- Direct Drive
wave > special electrical machine
- Hydraulic
wave > piston > high pressure oil > pipe > hydraulic motor > conventional electrical machine >
- Mechanical Linkage
wave > velocity increase > conventional electrical machine

OffShore Wind Power

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Charge Controller
-Control the flow of current to the battery and prevents the battery from over-charging.
Battery
-Stores electrical energy
Inverter
-Converts DC to AC
(The charge controller determines the operating point

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Part 2 (Direct Connected)

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Part 2 (DFIG)

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Q3 (b) Pelamis and AWS
The Pelamis uses a hydraulic motor. Hydraulic motor is operated by pressure differential between two sides of the motor.
AWS uses Linear Generator. Linear motion directly converted to electricity.

both use AC-DC-AC Converter. the generator side diode rectifier no requirement for DC. grid side inverter outputs power at grid frequency and voltage.

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(c)  Maximum power point (MPP) is the point on a power (I-V) curve that has the highest value of the product of its corresponding voltage and current (aka highest power output)

(d) Hill-climbing algorithm starts by calculating the Power from measured Voltage and Current, then compared to the previous results to obtain difference in power and voltage. Slope=(Difference in power)/(Difference in voltage).
If the slope is >0, duty cycle will be increased so voltage is increased.
If the slope is <0, duty cycle will be decreased so voltage is decreased.
Measurements required = Voltage, Current, Solar radiation level, Irradiance level
(e)

(f) Bypass diodes allow series of connected PV cells to continue supplying power at a reduced voltage rather than no power at all. This means if one of the PV cells has a defect or does not have solar radiation, the rest of the PV cells can still continue to supply current.

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Inverter/Power Conditioner
-Converts DC to AC that matches the grid
-Controls the power flow of the PV array
Distribution Panel
-distributes the power flow accordingly
Electric Utility
-The AC power grid that connects to the distribution network
(The Power Conditioner determines the operating point)

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Part 2 (Direct-drive synchronous)