Analyzing Eieetrieity Markets Considering The Transmission Constraints Based On Gametheory

In recent years, the electricity industry throughout the world has been undergoing restructuring. Competition has been introduced in order to improve operational and investment efficiency. However, the electricity market is an oligopoly in that the participants have market power, being able to influence the price by strategic action. The analysis of strategic behaviors and possible operation results in the electricity market seems particularly important. A key concept in analyzing oligopolies is the Nash Equilibrium (NE), which is thought of as a rigorous solution for bidding strategies in electricity markets. This study is important for both regulatory entities and market participants, in that the former have the duty to design and monitor the markets to ensure full competitiveness, and the latter are interested in optimal strategies for maximizing profit. However, it is difficult to solve the market equilibria problem, since the particular characteristics of an electric power system, such as transmission constraints, complicate the market clearing mechanism and make the payoff functions non-differentiable and non-concave.This dissertation addresses issues of equilibrium analysis of complicated electric power market considering the transmission constraints. The main work and key contribution of this dissertation are as follows:1. This dissertation proposes a new electricity market equilibrium model based on the Linear Supply Function Equilibrium (LSFE) model. In the proposed model, transmission constraints in addition to generation constraints and consumers bidding behavior are considered. A coevolutionary computation approach is proposed to solve for market equilibrium. Several cases from two sample systems are tested to verify the effectiveness of the proposed method which avoids being trapped in local optimum when searching for Nash Equilibrium. Simulation results indicate that the proposed approach rapidly converges to the pure strategy Nash Equilibrium if it exists. Further, it is observed that the existence of the pure strategy equilibrium is not simply determined by the existence of transmission congestion. The consumer strategic behavior and the generation constraints will also have impacts on the equilibria.2. It is a key problem to calculate the Nash equilibrium for the deregulated electricity market, and the problem mainly has two difficulties:computation of the mixed strategy Nash equilibrium and determination of whether multiple equilibria exist. Cournot model considering the network constraints is presented in the dissertation, then the solving system of polynomial equations algorithm, which is an algebraic method and belongs to the payoff matrix approach, is proposed to calculate the all Nash equilibrium for the finite-strategy multi-player game in the electricity market. The proposed approach mostly relies on decomposing the game by means of the support sets, and for each support set, the condition of the Nash equilibrium can be characterized by a system of polynomial equation and inequalities, then the all Nash Equilibrium could be found through detecting all the solution. Several examples base on the three-bus text system are used to investigate the effectiveness of the proposed approach, and the results show that the approach is capable of finding all Nash equilibrium under certain condition, which indicate that it has the potential to be used in the study of the real-world electricity markets.3. Distributed generation and interruptible load are two important resources of the smart grid. Because different kinds of power users have different willingness to curtail their demands, the type of the interruptible loads owned by a distribution company (DISCO) is assumed to be a stochastic variable which meets a discrete distribution. Further an energy acquisition model with the distributed generation and the interruptible load under incomplete information is formulated for the distribution company. Comprehensively taking into consideration of the strategic behavior of a generation company (GENCO), the integrated electricity market model under incomplete information is proposed finally. The coevolutionary approach is improved and further employed to solve the Bayesian Nash equilibrium of the market model. The IEEE 9-bus system appropriately modified is used to illustrate the proposed model and approach. The simulation results show that the market equilibrium is affected greatly by the distributed generation and interruptible load, the strategic behavior of the generation company and the incomplete information.4. There exist many uncertainty factors in the planning and operation process of electric power system. Therefore it is an urgent task to analyze electricity market taking into account these uncertainties. The paper proposes a supply function equilibrium model considering load uncertainties and random branch outages. The set of possible operational states of power system is determined by enumerating the uncertainties. A generation company pursues the maximum expected revenue comprehensively considering each system operational state. The coevolutionary approach is improved and used to solve the stochastic market equilibrium. Finally the analysis for a 9-bus sample system demonstrates the rationality and validity of the proposed market model and approach.