Tidal Turbine Inverters
Ario’s Tidal Turbine Inverters are state of the art power generators that are easy to install, generate no harmful greenhouse gasses and harvest renewable energy with very little environmental impact.
The variable speed drives operate as rectifiers (AC to DC conversion), while the grid-facing converter operates as an inverter (DC to AC inversion).
The grid-facing converter works as a DC link voltage regulator, it increases the power injection into the grid while the DC link voltage is too high, continuing to do so until the DC link voltage drops to within the operational band. Similarly, when the DC link voltage is too low, the grid-facing converter reduces the power injection into the grid to allow the DC link voltage to rise.
The variable speed drives are capable of producing variable voltage and frequency waveforms, which are applied to the stators of the induction machines. Under normal operating conditions, the variable speed drives operate in regenerative mode and take power from the induction machines and supply power to the common DC circuit, where the grid-facing converter converts the DC into AC power for exporting to the grid.
The grid-facing converter pumps the DC power it receives from the two variable speed drives into the three-phase grid. The control electronics of the grid-facing converter ensures that the sinusoidal voltage produced is synched to at the same frequency as the grid frequency. Then, by varying the relative phase and amplitude between its output voltage and that of the grid, the power flow into the grid is regulated.
The Ario VSDs and multilevel Inverter can also be used to implement a Tidal Turbine farm. In this implementation, the turbine platforms will contain only the variable speed drive (VSD) inverter. The VSD will be connected to a local grid DC grid of the system, which will be daisy chained between platforms. The main shore cable will be a DC cable (2 core vs 3 core required for AC). The larger shore inverter will then convert the incoming DC to AC, required for connection to the grid.
The Ario multilevel inverters will allow for a higher DC voltage on the locally created grid connection by stepping up the voltage from the generators. This results in lower currents which in turn results in lower cable losses and a decrease in the required cable size.
The advantages of this implementation include:
- • One DC shore cable with shorter interconnection DC cables to each turbine platform.
- • One DC to AC inverter on the shore.
- • Easier maintainability as the inverter sits on-shore and smaller inverters on the platform.
- • Lower losses due to higher DC grid voltage.
- • Smaller cable size.
- • Less weight on the platform.
- • Possible integration with other renewable energy sources.
- • This makes the integration of batteries easier because DC is sent to the shore.