Power Quality Engineering - Products > Hybrid Reactive Power & Harmonic Filter

CASE STUDY 8 - Emu Downs Wind Farm - Supporting the Grid

As world wide anxiety rises over dwindling fossil fuel reserves, power utilities are doing their best to meet the ever growing demand for electrical energy. Producing electrical energy from the power of the wind is the fastest growing form of green power generation, despite the many problems facing the utility wishing to feed wind generated electricity to the national grid.

The early engineering feats of overcoming the primitive problems inherent in producing high quality alternating current from propellers turned by an inconsistent wind, have given way to demands by electrical power utilities to not only meet local grid code, but to aid in grid balancing of reactive power.

One of the largest wind power generation farms has started production in Western Australia, producing electricity to be uploaded to the national grid at 132 kV. Designed to produce enough electricity for 50,000 households the Emu Downs wind farm utilizes 48 turbines of 1.65MW each to produce a total of 80MW of generated power.

A power station such as Emu Downs has to meet the national grid code regarding the quality of the electricity produced. Grid operators must be able to control the voltage of the power station, as well as depend on the station as a donor to centralized reactive energy control.

The heart of the voltage and reactive energy control at Emu Downs is the RTRPC. The RTRPC places 32MVAr of reactive energy at the fingertips of the grid operator, for controlling the voltage of the power uploaded, and for delivering reactive energy when required, all within a quarter of a cycle. The RTRPC also offers local support, with transient-free power factor correction, voltage sag ride through, and for correcting voltage flicker.

This 32MVAr RTRPC is designed to work at 22kV network. The system includes the following components:

8 units of 4MVAr RTRPC at 690V (each RTRPC consists of two cabinets)
8 step-up transformer, 22KV / 690V, 4.5MVA

The implementation of LV capacitors and step-up transformer to MV application was preferred over MV capacitors due to better cost to performance ratio.

The following drawing illustrates the complete system and the site single line diagram:

Figure 1 : System Overall Diagram

Figure 2 : System Single Line Diagram

Real Time Reactive Power Compensation System (RTRPC) in Wind Turbine Industry
RTRPC systems offer energy efficiency and voltage control to both the electrical supplier and the energy consumer. RTRPC is specifically engineered for the wind energy market, and supports the utility requirements for stable voltage, reactive energy supply to the network and voltage control to support network failures. The RTRPC features communication protocols that match its controller to the algorithms of leading wind turbine manufacturers worldwide.

Before choosing RTRPC, the customer checked for SVC and DVAR solutions. RTRPC provided less losses then the alternatives, shorter delivery time and proven experience as well as all benefits of the world fastest Thyristor Switched Capacitor bank.

Figure 3 : 32MVAR RTRPC System installation at the substation

Figure 4 : System Step Down Transformer

RTRPC Main Benefits in WTG

Grid Code requirements (Voltage flickering, Voltage control, Ride through)
Enhancement of production capacity
Cycle-by-cycle reactive power compensation (total acquisition time of 5-20 msec)
Transient-free solid-state capacitors switching
Reduction of current and voltage drop during WTG startup
Supports both local and central compensation
Prevention of resonance between the capacitors and the network
Improvement of reliability and reduction of maintenance costs
Remote operation from wind farm control center and/or grid control center
Option for supply of excessive reactive energy
Proprietary communication protocol to leading turbine manufacturers.
Full Customization for Customer special requirements
Hundreds of installations worldwide

Figure 5 : WindFarm, Australia

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