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

CASE STUDY 1 - Challicum Hills Wind Farm Grid-Connected Real Time Transient Free Reactive Power Correction System


Figure 1: Challicum Hills Wind Farm, Victoria, Australia		Figure 2: RTRPC System

The 52.5MW Challicum Hills Wind Farm, shown in Figure 1, was Australia’s largest wind farm when completed in August 2003. Located private farming land just east of Ararat in western Victoria, the wind farm generates enough clean electricity to supply 26,000 Victoria homes every year.

Installation and Functionality
The Challicum Hills Wind Farm is connected to the national electrical grid at 66kV. The 52.5MW wind farm is comprised of 35 wind turbine generators (WTGs), each with a capacity of 1.5MW.

Four individual 2.1MVAr Real Time Reactive Power Correction Systems (RTRPC), as seen in Figure 2, were installed for central power correction. The systems are connected to the wind farm’s 22kV distribution lines using step-up transformers. Each system uses a separate measurement reference point within the wind farm, shown in Figure 3, to make the necessary calculations for proper compensation.

The connection and disconnection of capacitors is controlled at 690V. The 22kV measurements are taken directly by the RTRPC controller at each cycle, while the wind farm SCADA (Supervisory Control and Data Acquisition) system periodically updates the 66kV voltage information at the controller through serial communication. The SCADA system also allows wind farm personnel complete control of the RTRPC, including all setup parameters and performance monitoring from the main wind farm control station, either on-site or remote.

Each RTRPC connects or disconnects steps based on sophisticated control algorithms which consider four separate parameters: power factor (PF), reactive power (kVAr), voltage at 22kV distribution and power utility transmission voltage of 66kV. The PF and reactive power are monitored and used for reactive power compensation, while the voltage measurements are used for voltage control functions.

Voltage control consists of two simultaneous operational modes: voltage regulation and voltage ride-through. The former is used to continuously adjust the wind farm voltage output, according to the measured voltage at 66kV, while the latter is used to support the wind farm network in case of short circuit or other significant voltage drop. A third voltage control function uses a safe voltage value that disconnects all capacitors in the system if a potentially unsafe ‘high’ voltage is measured.

RTRPC Performance
“The fast and accurate compensation response of the RTRPC system was observed during all monitored conditions. The system showed an immediate reaction to all changes in reactive energy within the resolution and power compensation limits.”

“The voltage control functionality of the RTRPC system has shown ability to maintain the voltage levels under desired limits during all monitoring conditions.”

RTRPC Benefits
Pacific Hydro Limited, who owns this wind farm, benefits from RTRPC reactive power correction system in the following ways:

Cycle-by-cycle reactive energy correction based on either PF or reactive power target values.
Stabilization of the wind farm’s voltage output to meet utility requirements.
Transient-free correction, which provides longer system life expectancy and extends the lifetime of ancillary equipment.
Network / grid voltage support in the event of sudden and significant drops in supply voltage.
Over-voltage protection through the ability of the RTRPC to disconnect all capacitors in case this potentially dangerous condition develops.
Remote system management, control and monitoring through integration with the wind farm’s
SCADA system.
Automatic notification of any system malfunction. An email and/or SMS (Short Message
Service) message is automatically sent to the appropriate personals.

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