Analysis of bids and re-bids of generators in the Australian National Electricity Market

In Australia´s National Electricity Market (NEM), generators provide their bids and re-bids in 0.5 hour trading intervals. Spot prices are determined in 5-minute periods by the intersection of the bids and power demand. Generator bids and re-bids are composed of power price determined in 10 pricing bands and power offered in 0.5 hour intervals. Generator´s behaviour depends on several elements such as daily demand forecasted, maximum system capacity, the generation reserve predicted, transfer between the regions. The paper presents generator bids and re-bids based on two main aspects: distribution of prices and power offered in price bands. The functional relations for various days of a week, months and seasons for three main categories of power stations: thermal, gas and hydro are subject to the analysis carried out for two main regions of the National Electricity Market (NEM) in Australia. Statistical distribution functions of typical bidding behaviour are derived allowing the prediction of future pool prices.