Dynamic Ex-ante Market Power Analysis Method In Electricity Market

Domestic power system is facing the dual opportunities of rapid development of renewable energy and steady advancement of the electricity spot market.Electricity spot market is an important platform for power trading,whose clearing process needs to consider the output flexibility constraints such as the unit's maximum and minimum output,ramp rate constraints and start-stop constraints,which enables the suppliers to use the flexibility constraints to exercise market power.At the same time,with large-scale intermittent renewable energy integrating to the grid,the power system requires a large number of highly flexible units to maintain the operation efficiency.The shortage of flexible power generation resources will increase the possibility of suppliers to exercise market power.Therefore,this paper established a dynamic ex-ante market power analysis method which considers the output flexibility of the unit.Traditional ex-ante market power analysis methods mostly identify the market power from the electricity supply and demand,market share and transmisson constraints in a single period.Due to the neglect of the unit's output flexibility constraints,especially the impact of multi-period coupling constraints,the traditional methods may cause the "false positive" or "false negative" error of the identification of market power in the electricity spot market.In view of this,this paper established a dynamic ex-ante market power analysis model based on the SCED and SCUC model,and considered the impact of unit flexibility constraints on the formation of market power in the spot market to avoid the "missing report".In order to avoid the"false report" of market power,the key bidding blocks to be tested are constructed after the units submit their bidding curve,and the market power testing are implied for them.Then,we can make the accurate detection of where and when the market power will emerge.This model is a mixed integer nonlinear programming problem.We used linear algebra technology to convert it to mixed integer linear programming problem,which greatly reduced the difficulty of model solving.The dynamic ex-ante market power analysis model in the paper is implemented in GAMS and solved by using CPLEX.The results show that the unit ramp rate constraints,unit start-stop constraints and transmission constraints can form market power in the spot market and the combination of multiple constraints may further expand the market power which verified the effectiveness of the proposed model.