In the abroad electricity spot market

a flexible block order is the new designed transaction category in the bidding mechanism. It allows the market members to select the diversified and personalized transaction mode according to the technical characteristics of the power generation and the actual demand of the electricity

which enriches the liquidity of trading market. This kind of mechanism has the reference value for China to carry out the construction of electricity spot market pilot. Therefore

the operating mechanism of the Nordic electricity spot market is briefly introduced

and the definition and characteristics of trading varieties including hour order

flexible order and block order in the spot market are described. On this basis

a clearing model for electricity spot market with the complex bidding of flexible block order is established combined with the design of the spot market transaction mechanism. Since the model belongs to the multi-period

large-scale and nonlinear mixed integer programming problem

a linear modeling method to reduce the nonlinearity of the model is proposed to improve the efficiency of the model. Finally

the example analysis is given to illustrate the correctness and validity of the proposed model and the solving method.