Security Region Based Real And Reactive Power Pricing Of Power System And Congestion Management

Electricity marketization, power grids interconnection and wind farm connected with power system have brought new challenges. Power systems are operated more and more close to the stability border, and transmission congestion is increasingly severe. Therefore, it is worth researching that how to make full use of the competition mechanism and price means to stimulate market members participating in the maintenance of system security actively. In this dissertation, active and reactive power pricing and reasonable congestion cost allocation, as well as the impact of wind farm on power system optimal operation are studied using security region methodology.Firstly, a pricing model of real and reactive power based on security region and the corresponding algorithm are developed. The static voltage stability region in the cut set power space and the practical dynamic security region in the injection power space are used to represent the constraints of voltage stability and transient stability. In the proposed model, the objective function is to minimize total generation costs, and the reactive power production cost is represented as the opportunity cost. All the variables in the objective function and constraints are injection power space values of pre-fault, and different contingency considerations are reflected by the constraint expression coefficients. These make the model not only more convenient to consider the contingency set, but also have concise expressions and clear physical meaning. In the proposed algorithm, a decoupled optimization and iteration method of active power production cost and reactive power production cost is suggested. Using the theory of marginal cost and K-T optimality condition, active power and reactive power are priced respectively, and the component prices related to various security constraints are derived. The components of spot price can reflect the influences of different node power injections on each kind of security constrains, thereby the market participants can be motivated to cooperate with the transmission network dispatchers forwardly by the spot price, to maintain system security through real-time adjustment of their generation and consumption behaviors.Secondly, the congestion management model based on security region is presented, which contains transmission line thermal stability constraint and static voltage stability constraint and transient stability constraint simultaneously. The current network configuration and post-fault network configuration are all considered in the security constraints, which makes the model more reasonable. The derived spot prices containing security constraint components imply the allocation of congestion cost. For the emergence of passive over-limit constraints, a method of modifying the integral initial value of Aumann-Shapley value is proposed and its rationality is discussed. This method ensures the integral request along the main diagonal of Aumann-Shapley value formula, and makes the passive over-limit constraints not to participate in sharing the congestion cost, and realizes the reasonable allocation of the congestion cost between market participants.Finally, the active power pricing model based on security region is applied to the feasibility study of wind farm location and its capacity. The hourly average daily generation curve is used to express the wind farm operation constraint and the load changes over time are reflected through the scaling factor. Due to the consideration of line thermal stability constraint and transient stability constraint, the impact of installed location and capacity of wind farm on market price, generation cost and security cost can be studied more accurately. The rationality criterion of wind power investment is proposed according to the market price. The results of impact analysis can help power grid planners and wind power developers assess the integration of wind farm into power grid scientifically.