Low Load Frequency Support Capability - Collie Power Station

Energy markets around the world are in a transitional phase, where wind and solar generation are penetrating the markets at unforeseen rates. The desire to decarbonise emissions associated with power generation in Australia, is seen as the first step in meeting our commitments to the Paris Climate Change Agreement. This has had a significant effect upon the electricity grid within Western Australia. The high volume of renewable generation is creating grid instability during times of low demand. This is a result of fluctuations in generation due to the variability of wind and solar. Network strength is no longer as robust because of the loss of synchronous inertia that was behind a grid mainly powered by thermal machines. Many coal fired stations are attempting to become more flexible and change from base load to cyclical operation to assist counteract the irregular nature of wind and solar generation. Collie Power Station is one such station, attempting to improve its operational flexibility. One aspect is the desire that the station move from a current minimum load setpoint of 130MW to 105MW (generated) to assist the station remain dispatched at low load rather than desynchronising it from the grid. The aim of this dissertation is to model the frequency support capability at 105MW to determine if the station continues to provide frequency support for the grid. The provision of frequency support is an important aspect of grid stability for the West Australian electricity grid. Renewable generation does not currently provide such support service, so the provision must be covered by the reducing number of synchronous machines. Collie Power Station has been modelled within MATLAB Simulink, with the model successfully verified using the station’s historical data. The model has been used to evaluate the frequency support capability at the proposed minimum load set point of 105MW (generated). The results indicate that that the unit can contribute to grid stability when frequency deviations occur. This low load capability enhances the stations ability to support the grid as the transition to even higher levels of renewable generation continues