| With the increasingly severe global energy pressure and environmental problems,governments in all countries are vigorously developing renewable and clean energy sources to replace traditional energy consumption.As the most potential for commercial development and the fastest-growing energy application technology,wind energy has been unprecedentedly developed in recent years.However,the unstable wind power output characteristics such as randomness has a great impact on the security and stability of the power grid,which seriously restricts its large-scale grid-connected consumption and long-distance scheduling and transmission.At the same time,the continuous maturation of the electricity market has resulted in a complete reversal of the original planned electricity trading system.The marginal benefit of renewable energy due to its own generation costs is almost zero,and there is a natural price advantage in market transactions.Wind power will gradually be concerned by market participants.In short,whether it is the main alternative resource for energy transformation or the price advantage of market transactions,under the premise of guaranteeing the safe operation of the power grid,the penetration rate of wind power in the power grid is gradually increased,and the scale of wind power trans-regional market transactions is steadily increased.The available transmission capability(ATC)of the power grid is not only an important technical indicator to measure the safety and stability of the system,but also a key criterion for market participants to understand the transmission resistance and make economic decisions for market risk.How to effectively evaluate the available transmission capacity of large-scale wind power grid-connected systems in the electricity market environment has become a problem that needs to be solved urgently.Firstly,this thesis establishes a wind power probability density model suit able for ATC evaluation.The "tail" phenomenon of wind power output cannot be well fitted with the common single distribution function.This thesis constructs a wind power probability density model using weighted Gaussian mixture model,then uses the annealing mechanism of DAEM algorithm to solve the drawbacks of EM algorithm that are vulnerable to initial values when WGMD model parameters are estimated.The proposed method improves the precision of parameter estimation and the fitting effect of the model significantly.Secondly,the Markov Chain Monte Carlo simulation algorithm based on Gibbs sampling has many applications in considering the influence of many uncertain factors on the operation of the grid.However,the Gibbs sampling process is susceptible to the multi-peak interference of the probability density distribution,and it is easy to sample non-uniformly,resulting in a local optimum of the sample space.In this thesis,the use of slice reflection sampling compared with Gibbs sampling in ATC evalu ation,the same number of sampling times in IEEE 30-bus system with wind power integration is performed,verifying that the proposed slice reflection algorithm sampling is more stable and more accurate.Finally,the thesis introduces the commonly used risk value and conditional risk value methods in the financial industry,taking into account the impact of the fluctuation characteristics of wind power on the safe operation risk of the system and the marginal cost advantage of wind power generation to the ec onomy of the electricity market.Then,this thesis takes the risk economic value of market participants as the objective function and builds an ATC economic risk assessment model that is consistent with the power market transaction.At the end of the thesis,the economic benefits of different ATCs faced by market players are analyzed through calculation examples,which provides an effective reference for the smooth development of power market transactions and the allocation of resources for power grid dispa tch. |
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