Bidding Theories And Its Application For Cascade Hydropower Stations Under Uncertain Electricity Market

In China, there are abundant water resources in the large rivers of twelve hydropower bases which have advantages in cascade development. With the construction and operation of the cascade hydropower stations in the basin and the formation of national interconnected electric network, the allocation optimization and effective utilization of the water resources in the basin has already become an important problem which has impact on the national energy security and economic development. Simultaneously, the electric industy reform has being carried out all over China in order to improve the operation efficiency of electric system under the background of national interconnected electric network and thereafter generation-side electricity market has been set up. These have fundamentally changed the operation environment of cascade hydropower stations. The bidding strategy of cascade hydropower stations is an important content of its optimal operation under multi-level electricity markets and need the support of relevant theories and technologies urgently. In this respect, the scholars have carried out extensive researches and obtained useful results. However, the electric industy reform in China has a short duaration, its energy policys, market rules and market information transfermation mechanism are far from perfect, the structure of electric network are different from that in other countries, the uncertain factors which includes the competition and cooperation of market agents, the fluctuation of electricity demand and market price, the demand-price elasticity and the behavior of competitors interact with each other. These made the optimal bidding strategies of cascade hydropower stations a complex multi-step, multi-stage and multi-level market gaming and decision-making problem which is hard to model and solute. The existing reseach results are difficult to adapt directly to solute the problem which calls for the breakthrough of bidding theories and methods.Surrounding the competition and conflict of cascade hydropower stations in uncertain electricity market environment, using the analysis of the impact of the uncertainties on bidding strategies of cascade hydropower stations as an entry point, this paper introduces the theories of system optimization, probabilistic interval price forecasting, (non-) cooperative game theory to constructe the bidding game and decision-making model of cascade hydropower stations under multi-level electricity market environment considering the generation constraints of cascade hydropower stations, the change of market policy, incomplete information, competitor's behaviors, the competition and cooperation among market agents. Based on these models, the optimal bidding strategies of cascade hydropower stations are obtained and the response mechanism are revealed that bidding strategy of cascade hydropower stations to the uncertainties which includes market policies, incomplete information, competitor behaviors, demand-price elasticity and the change of generation costs. Besides, a bidding decision support system of cascade hydropower plant has been designed and implemented. These results provide theoretical basis and technical support for the operation optimization of cascade hydropower stations in multi-level electricity market environment. The main contents and innovations of the paper are stated as follows:(1) According to the characteristics of market clearing price, two deterministic price forecasting models are set up based on which a probabilistic interval price forecasting model using error statistical analysis and fitting are constructed to overcome the disadvantage of deterministic price forecasting model that it can not provide comprehensive information of the forecasting price.(2) Based on the analysis of the characteristics of different bidding modes, the optimal bidding model of the cascade hydropower stations in long-term and middle-term contract electricity market are constructed and soluted considering the generation cost characteristics and the expected profit return. After that, the optimal bidding strategy of cascade hydropower stations in the day-ahead electricity market is presented based on the results of probabilistic interval price prediction.(3) In order to realize global optimization of market agents, the Stackelberg and Cournot game model under both complete and incomplete information for the bidding process in the day-ahead market are constructed to derive the optimal strategy for the cascade hydropower stations and discover the mechanism that the energy policy and incomplete information affect the market equilibrium and the profits of generators. The supply function equilibrium model of day-ahead electricity market has also been set up to discuss the competition among the market agents. Based on the model, the laws are revealed how the bidding behaviors of competitors, demand-price elasticity and generation cost affect the market equilibrium and the bidding strategies of cascade hydropower plant and its competitors.(4) Considering the allocation optimization of the basin cascade hydropower energy under electricity market condition, the possibility of the cooperation between cascade hydropower stations and the grid company which is the only purchaser in the day-ahead market are discussed. The law has been revealed how the bidding strategy of cascade hydropower stations affects the market clearing results. Based on the results, the necessary condition for the cooperation between the generator and the grid company are derived and the impact of the cooperation on the market clearing results has also been analyzed. Besides, an effective and feasible profit allocation method is design for the two sides. All these results construct a new road for the allocation optimization of hydropower resources.(5) Based on the bidding theories above, the physical structure, functional structure, main functional moduals and logic structure of the bidding decision support system have been designed for three gorges cascade hydropower stations, the development and integration of the system are realized.