Font Size: a A A

Optimal Transmission Expansion Planning Based On Both Static And Dynamic Security Risks

Posted on:2007-04-15Degree:DoctorType:Dissertation
Country:ChinaCandidate:C H MaFull Text:PDF
GTID:1102360182486815Subject:Power system and its automation
Abstract/Summary:PDF Full Text Request
Transmission expansion planning plays a critical role in power system planning. According to the growth of future generation and load demand in the planning period studied, the goal of transmission expansion planning is to select new transmission lines based on existing transmission network to ensure the secure and economical operation of power system. With the rapid development of nationwide transmission network, new criteria and approaches are required for transmission expansion planning. In this dissertation, The present status of transmission planning is reviewed from various viewpoints and the new requirements of transmission planning resulting from development of electricity markets are discussed. The characteristics of different algorithms on transmission planning are analyzed and compared. The paper also pionts out that the security risk of tranmission system, expressed by quantitative indices, should be considered in the objective function. Under two different conditions, namely, certain or uncertain injection power at the buses, transmission expansion planning models and the methods to solve them are put forward.Several large-scale blackouts in the world have attracted attentions to dynamic and static security of transmission expansion planning. The optimal planning scheme should satisfy the demands for economy and security. Usually, the security in transmission planning model is qualitatively verified by the given limit such as active power, power angle, voltage, frequency, etc. There are two main reasons: one is there is no likelihood to quantify the security because the critical statement of instability cannot be identified accurately;the other is that it is difficult to quantify the costs beyond limit. So the security cannot be presented as economical indices in the objective function, only to be expressed as the inequation restriction in transmission planning model. The paper points out that the costs of insecurity should be accounted by its optimal controls, and then the security risks, which is included in the objective function, can be calculated with the given fault probability to be compared with the investment of transmission lines. Therefore the security and economy of transmission expansion planning can be kept in the balance simultaneously.The security of the transmission network can be strengthened by expanding transmission lines or adopting controls. Obviously, the best solution is the coordination of the two. The serious fault with small probability can be solved not only by expanding transmission lines.This paper builds a transmission planning model considering both static security risk and dynamic security risk with probabilistic N-l safety criteria. A global optimization framework is developed to resolve the problems cauesed by the multi-object mathematical model and remarkably reduce the computational burden. Based on EEAC, the proposed method can calculate the stability margin and dynamic risks, identify the grid bottleneck, and can provide guidance to the line expansion.Compared with the transmission expansion planning in the traditional vertically integrated industry, the transmission expansion planning in the electricity market environment has been confronted with much more uncertain factors, such as the locations and capacities of new power plants, and the the electric power demand in the planning period studied, which make uncertain injection power at the buses. In order to ensure a flexible transmission system in the electricity market environment, the paper extends the transmission planning model, which considers both static security risk and dynamic security risk, to deal with uncertain injection power. A global optimization framework is developed to resolve the problems cauesed by the multi-object mathematical model and uncertain power injections. A numerical example is presented to illustrate the validity of the method.The research work is of significance both on theory and in practice, providing feasible methods and principles for the interconnection and market management of nationwide transmission network.This work is jointly supported by Special Fund of the National Basic Research Program of China(No. 2004CB217905), National Natural Science Foundation of China(No. 50595413)and State Grid Corporation of China(SGKJ[2004]392).
Keywords/Search Tags:transmission expansion planning, optimal planning, security, risk, extended equal area criterion(EEAC), genetic algorithm(GA), electricity market, uncertainty, Monte Carlo simulation
PDF Full Text Request
Related items