Market power assessment through modelling of effective anti-competitive behaviour of participants

Market power is an anti-competitive issue in the electricity markets, the identification and monitoring of which require using comprehensive and accurate indices. In this study, two new behavioural indices are introduced for the effective and accurate monitoring of market power. The suggested indices determine the actual level of market power in the transmission-constrained electricity markets by analysing the bidding behaviour of participants. The proposed indices necessarily consider the success of the participant's anti-competitive behaviour in a price increase on the basis for computation. First, the effective physical withholding index is presented, which can determine the amount of physical withholding that has led to the acceptance of a more expensive block. The effective financial distortion rate index is then proposed, which can specify the degree of financial deviation of the participants resulting from the successful exercise of each participant's withholding (financial-physical) strategy. Investigation of the results obtained from a three-bus test system and the IEEE 57-bus test system verifies the effective and accurate performance of the proposed indices in assessing the market power.